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NAVEDTRA 12848 Training Manual (TRAMAN)Naval Education and September 1997 and Nonresident TrainingTraining Command 0502-LP-012-8750 Course (NRTC)
Radioman TrainingSeries
Module 4—Communications Hardware
Only one answer sheet is included in the NRTC. Reproduce therequired number of sheets you need or get answer sheets from yourESO or designated officer.
DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.
The public may request copies of this document by followingthe purchasing instruction on the inside cover.
0 5 0 2 L P 0 1 2 8 7 5 0
Although the words “he,” “him,” and “his” areused sparingly in this manual to enhancecommunication, they are not intended to be genderdriven nor to affront or discriminate against anyonereading this text.
DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.
The public may request copies of this document by writing to Superintendent of Documents, Government Printing Office,Washington, DC 20402-0001 or to the Naval Inventory Control Point (NAVICP) - Cog “I” Material, Attention CashSales, 700 Robbins Avenue, Philadelphia PA 19111-5098.
RADIOMAN TRAINING SERIES
MODULE 4—COMMUNICATIONSHARDWARE
NAVEDTRA 12848
1997 Edition Prepared byRMCS(SW/AW) Deborah Hearn and
DPC(SW) Walter Shugar, Jr.
PREFACE
This training manual (TRAMAN), together with its nonresident training course(NRTC), NAVEDTRA 12848, form a self-study training package for personnelfulfilling the requirements of the Radioman rating. The TRAMAN provides subjectmatter that relates to the occupational standards for the RM rating. The NRTCconsists of two assignments to help the student complete the TRAMAN.
This edition includes information on communications hardware and satellitesand antennas.
This training manual was prepared by the Naval Education and TrainingProfessional Development and Technology Center, Pensacola, Florida, for the Chiefof Naval Education and Training.
1997 Edition
Stock Ordering No.0502-LP-012-8750
Published byNAVAL EDUCATION AND TRAINING PROFESSIONAL
DEVELOPMENT AND TECHNOLOGY CENTER
UNITED STATESGOVERNMENT PRINTING OFFICE
WASHINGTON, D.C.: 1997
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THE UNITED STATES NAVY
GUARDIAN OF OUR COUNTRY
The United States Navy is responsible for maintaining control of the seaand is a ready force on watch at home and overseas, capable of strong actionto preserve the peace or of instant offensive action to win in war.
It is upon the maintenance of this control that our country’s gloriousfuture depends; the United States Navy exists to make it so.
WE SERVE WITH HONOR
Tradition, valor, and victory are the Navy’s heritage from the past. Tothese may be added dedication, discipline, and vigilance as the watchwordsof the present and the future.
At home or on distant stations as we serve with pride, confident in therespect of our country, our shipmates, and our families.
Our responsibilities sober us; our adversities strengthen us.
Service to God and Country is our special privilege. We serve withhonor.
THE FUTURE OF THE NAVY
The Navy will always employ new weapons, new techniques, andgreater power to protect and defend the United States on the sea, under thesea, and in the air.
Now and in the future, control of the sea gives the United States hergreatest advantage for the maintenance of peace and for victory in war.
Mobility, surprise, dispersal, and offensive power are the keynotes ofthe new Navy. The roots of the Navy lie in a strong belief in the future, incontinued dedication to our tasks, and in reflection on our heritage from thepast.
Never have our opportunities and our responsibilities been greater.
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CONTENTS
CHAPTER PAGE
1. Communication shareware . . . . . . . . . . . . . . . . . . . .1-1
2. Satellites and Antennas . . . . . . . . . . . . . . . . . . . . . . .2-1
APPENDIX
I. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AI-1
II. Glossary of Acronyms and Abbreviations . . . . . . . . . . . . AII-1
III. References Used to Develop the TRAMAN. . . . . . . . . . . AIII-1
INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INDEX-1
NONRESIDENT TRAINING COURSE follows the index
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SUMMARY OF THE RADIOMANTRAINING SERIES
MODULE 1
Administration and Security—This module covers Radioman duties relating toadministering AIS and communication systems. Procedures and guidance forhandling of classified information, messages, COMSEC material and equipment,and AIS requirements are discussed.
MODULE 2
Computer Systems—This module covers computer hardware startup, includingperipheral operations and system modification. Other topics discussed includecomputer center operations, media library functions, system operations, andtroubleshooting techniques. Data file processes, memory requirements, anddatabase management are also covered.
MODULE 3
Network Communications—This module covers network administration, LANhardware, and network troubleshooting. Related areas discussed are networkconfiguration and operations, components and connections, and communicationlines and nodes.
MODULE 4
Communications Hardware—This module covers various types ofcommunications equipment, including satellites and antennas. Subjects discussedinclude hardware setup procedures, COMSEC equipment requirements, distresscommunications equipment, troubleshooting equipment, satellite theory, andantenna selection and positioning.
MODULE 5
Communications Center Operations—This module covers center operations,including transmit message systems, voice communications, center administration,quality control, and circuit setup/restorations. Guidelines for setting EMCON andHERO conditions and cryptosecurity requirements are also discussed.
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CHAPTER 1
COMMUNICATIONS HARDWARE
LEARNING OBJECTIVES
Upon completing this chapter, you should be able to do the following:
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Determine the equipment required for each communications system.
Identify the hardware setup procedures for radio systems.
Identify the use of COMMSPOTS.
Identify procedures and requirements for communications equipment as itpertains to OTAR/OTAT functions.
Determine utilization, frequencies and watches needed for distresscommunication equipment.
Interpret how to monitor circuit quality equipment.
The high-paced operations required of modern fleetunits demand communication systems that are capableof providing high-speed, accurate, and securetransmission and reception of intelligence. To keeppace with the ever-increasing complexity of operations,today’s communication systems are necessarily highlysophisticated and versatile. For our ships andsubmarines to operate effectively, whetherindependently or as part of a battle group, they musthave communication systems and operators that arecapable of meeting this challenge.
In this chapter, we will discuss various aspects offleet communication systems. As a Radioman, you willbe responsible for knowing the differentcommunication systems used by the Navy and whatcommunication equipments make up a system.
COMMUNICATIONS SYSTEMS
Through equipment design and installation, manyequipments are compatible with each other and can beused to accomplish various functions. Using this designconcept, nearly all the communication needs of a shipcan be met with fewer pieces of communicationsequipment than were previously required.
Communications can be maintained at the highestpossible state of readiness when all levels of commandunderstand the capabilities and limitations of thesystems. Many communications failures areattributable to poor administration rather than toequipment failure or technical problems.
In this section, we will discuss predeploymentreadiness; low-, high-, very-high-, ultra-high-, andsuper-high-frequency communications systems; andequipment components that comprise these systems.
UNDERWAY PREPARATION
Ships deploying to overseas areas must be in a stateof maximum operational and communicationsreadiness. Type commanders determine the level ofreadiness of deploying ships and ensure they areadequately prepared.
A check-off list is an excellent method to ensurethat step-by-step preparations are completed prior to adeployment. This list should cover all aspects ofcommunications readiness and should begin well inadvance of the underway period. Some of the points tobe checked include scheduling of communicationsassistance team (CAT) visits, maintenance and
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operational checks of equipment and antennas, andconsumable supply levels.
The Basic Operational Communications Doctrine(U), NWP 4 (NWP 6-01), provides suggestedminimum check-off sheets , inc luding apredeployment check-off sheet and a preunderwaycheck-off sheet. The first sheet provides a timetable ofrequired checks and objectives. The second sheet istailored to individual ships and unique requirements.
LOW-FREQUENCY SYSTEMS
The low-frequency (LF) band (30-300 kHz) is usedfor long-range direction finding, medium- and long-range communications, aeronautical radio navigation,and submarine communications.
A low-frequency transmitter, such as the AN/FRT-72, is used to transmit a high-powered signal overlongdistances. Low-frequency transmitters are normallyused only at shore stations or for special applications.
The low-frequency receive system is designed toreceive low-frequency broadcast signals and toreproduce the transmitted intelligence. A typical low-
frequency receive system is shown in figure 1-1. Referto the equipments in the figure as you study the nextsection.
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Antennas— The low-frequency signal isreceived by the antennas, which are connectedto the receiver antenna patch panels andmulticouplers (AN/SRA-34, AN/SRA-57, orAN/SRA-58). Multicouplers and patch panelsallow the operator to select different antennasand connect them to different receivers. Thisway, an operator can select the correctcombination suited for a particular system.
LF Receiver— The output of the receiver(audio) is fed to the receiver transferswitchboard.
Switchboard— The switchboard can connectthe receiver output to numerous pieces ofequipment. In figure 1-1, the receiver output isconnected to the AN/UCC-1 TeleprinterTerminal (discussed later).
AN/UCC-1— The AN/UCC-1, as a convertercomparator, converts the received audio signal
Figure 1-1.—Low-frequency receive system.
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(AF) to direct current (dc) for use by theteleprinter equipment.
Black dc Patch Panel— The dc output of theAN/UCC-1 is fed to the SB-1203/UG DC PatchPanel. The dc patch panel permits the signal tobe patched to any cryptoequipment (discussedlater) desired.
Cryptoequipment— The cryptoequipmentdecrypts the signal and connects its output to thered SB-1210/UGQ DC Patch Panel.
Red dc Patch Panel— The SB-1210/UGQ canbe patched to a selected printer that prints thesignal in plain readable text.
HIGH-FREQUENCY SYSTEMS
The high-frequency (HF) band (3-30 MHz) isprimarily used by mobile and maritime units. Themilitary uses this band for long-range voice andteleprinter communications. This band is also used as abackup system for the satellite communications system.We will discuss satellite communications later in thischapter.
Figure 1-2 shows a typical high-frequency transmitsystem. In transmitting teleprinter information, theequipments shown in figure 1-2 perform the samefunctions as the equipments shown in figure 1-1, exceptthe equipments in the high-frequency system do thefunctions in reverse order.
In the HF transmit system, the AN/UCC-1Telegraph Terminal converts dc signals into audio tonesignals. The output of the AN/UCC-1 is connected tothe transmitter transfer switchboard. The C-1004Transmit Keying and Receive Control/Teleprinter isused to key the transmitter during teleprinteroperations.
Voice communications from some remote locationsare also connected to the transmitter transferswitchboard. Voice communications are initiated at ahandset (remote phone unit) and connected to the C-1138 Radio Set Control. The output of the radio setcontrol is connected to the transmitter transferswitchboard. The transmitter transfer switchboardpermits the operator to select the proper transmitter forthe frequency to be transmitted.
Figure 1-2.—High-frequency transmit system.
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Figure 1-3.—High-frequency receive system.
Figure l-3 shows atypical high-frequency receivesystem. Refer to the figure as we follow the signal paththrough the system.
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A transmitted high-frequency signal is receivedby the antenna, which converts electromagneticenergy to electrical energy.
The signal travels through a transmission line toan antenna patch panel, where it can bedistributed to any of a number of receivers.
The receiver converts the RF signal into ateleprinter or voice signal, depending upon whatis desired.
The output of the receiver is then sent to thereceiver transfer switchboard.
If a teleprinter signal was selected, theteleprinter signal from the switchboard goes tothe AN/UCC-1 and then follows the same pathas we described in the low-frequency receivesection. Identical pieces of equipment are used,and they perform the same functions.
If a voice signal was selected, the voice signalfrom the receiver transfer switchboard is sent tothe radio set control. The output is then sent to ahandset. The voice signal can also be sent fromthe switchboard to a remote speaker amplifier.There, it can be placed on a speaker so that the
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user can listen to the received signal withoutholding onto the handset.
VERY-HIGH-FREQUENCY SYSTEMS
The very-high-frequency (VHF) band (30-300MHz) is used for aeronautical radio navigation andcommunications, radar, amateur radio, and mobilecommunications (such as for boat crews and landingparties). Figure 1-4 shows a basic block diagram of a
Figure 1-4.—Very-high-frequency transmit and receivesystem.
VHF transmit and receive system using a transceiver.Although a transceiver is used in this system, thetransmit and receive systems are described separately.Refer to figure 1-4 as we follow the signal path on thetransmit side of the system.
On the transmit side of the system, the operator, at aremote location:
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Talks into the handset.
The handset is connected to the C-1138 RadioSet Control.
The output of the radio set control is sent to thetransmitter transfer switchboard.
The output of the switchboard is sent to thetransmit side of the transceiver.
The transceiver converts the input signal to anRF signal for radiation by the antenna.
Continue to refer to figure 1-4 as we follow the path ofthe incoming signal.
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The incoming signal in figure 1-4 is received bythe antenna.
This signal is sent to the receive side of thetransceiver.
The output of the transceiver is sent to thereceiver transfer switchboard.
From the receiver transfer switchboard, theoutput is sent to either the C-1138 Radio SetControl or to a speaker amplifier, or both,depending on the preference of the user.
The output of the radio set control is sent to ahandset.
6. A speaker receives the output of the speakeramplifier.
ULTRA-HIGH-FREQUENCY SYSTEMS
The ultra-high-frequency (UHF) band (300-MHzto 3-GHz) is used for line-of-sight (short-range)communications. The term “line of sight,” as used incommunications, means that both transmitting andreceiving antennas must be within sight of each otherand unaffected by the curvature of the Earth for propercommunications operation.
The UHF band is also used for satellitecommunications. Although satellite communicationsare line of sight, the distance the signal travels is muchgreater than that of UHF surface communications,because the antennas remain in sight of each other.
As in the VHF section, the transmit and receivesystems will be described separately. Figure 1-5 showsa basic block diagram of a UHF transmit system, whichuses a transceiver.
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On the transmit side of the nonsecure voicesystem, the operator at a remote location talksinto the handset. The handset is connected to theC-1138 Radio Set Control.
The C-1138 is connected to the transmittertransfer switchboard, where it is patched to thetransmitter.
The operator at a remote location talks into thesecure voice remote phone unit (RPU).
The RPU is connected to the secure voicematrix. This is the tie point for connecting morethan one RPU. The output of the matrix is
Figure 1-5.—Ultra-high-frequency transmit system.
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connected to the secure voice equipment, whichencrypts the information received.
The output of the secure voice equipment isconnected to the transmitter transferswitchboard.
The transmitter transfer switchboard is used toconnect numerous RPUs to any number oftransmitters.
The output of the patch panel is connected to thetransmitter side of the transceiver, which, inturn, is connected to an antenna coupler.
Figure 1-6 shows a basic diagram of a UHF receivesystem. We will next follow the UHF signal paththrough the receive side of the system.
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The received signal is picked up by the antennaand connected to the receiver side of thetransceiver through the antenna coupler.
The output of the receiver is connected to thereceiver transfer switchboard. From here, it canbe connected to either the nonsecure or thesecure voice systems, depending upon the modeof transmission.
When a nonsecure signal is received, the outputof the receiver transfer switchboard can beconnected to the radio set control or a speakeramplifier, or both, depending on the preferenceof the user.
The output of the radio set control is connectedto a handset, whereas the output of the speakeramplifier is connected to a speaker.
If a secure voice transmission is received, theoutput of the receiver transfer switchboard is
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connected to the secure voice equipment, whereit is decrypted.
The secure voice equipment output is connectedto the secure voice matrix. The secure voicematrix performs the same function as the matrixon the transmit system.
The secure voice matrix output is connected tothe secure remote phone unit. Here, the signal isconverted back to its original form.
SUPER-HIGH-FREQUENCY SYSTEMS
The super-high-frequency (SHF) band (3-30 GHz)is strictly for line-of-sight communications. It isconfigured much the same as the UHF system. SHF ismainly used for satellite communications.
SHF satellite communications is a high-volumesystem that offers reliable tactical and strategiccommunications services to U.S. Navy elements ashoreand afloat. The system is composed of the terminalsegment, consisting of U.S. Navy-operated Earthterminals and mobile terminals. It also includes aportion of the Defense Satellite CommunicationsSystem (DSCS) satellite segment. Navy Super HighFrequency Satellite Communications, NTP 2, Section1 (C), provides comprehensive coverage of the NavySHF satellite system.
PATCH PANELS
Teleprinter patch panels are used for theinterconnection and transfer of teleprinter signalsaboard ship. In the previous block diagrams two patchpanels, one labeled red, the other black, were shown.These are the teleprinter patch panels SB-1210/UG and
Figure 1-6.—Ultra-high-frequency receive system.
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SB-1203/UGQ (figure 1-7). The SB-1210/UG isintended for use with cryptographic devices; the SB-1203/UGQ is a general-purpose panel.
The patch panels are red or black to identify secureand nonsecure information. Red indicates that secure(classified) information is being passed through thepanel. Black indicates that nonsecure (unclassified)information is being passed through the panel.
Both panels are also labeled with signs. The redpanel sign has 1-inch-high white block letters that read“RED PATCH PANEL.” The black panel normally hastwo black signs containing l-inch-high white blockletters. One sign reads “BLACK PATCH PANEL” andthe other, “UNCLAS ONLY.”
Each panel contains six channels. Each channel hasits own series circuit of looping jacks, set jacks, and arheostat for adjusting line current. The number oflooping and set jacks in each channel varies with thepanel model. Each panel includes a meter and rotaryselector switch for measuring the line current in anychannel.
Six miscellaneous jacks are contained in eachpanel. Any teleprinter equipment not regularlyassigned to a channel maybe connected to one of thesejacks. In some instances, commonly used combinationsof equipment are permanently wired together within thepanel (called normal-through).
Figure 1-7.—Teleprinter patch panels.
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CRYPTOGRAPHIC EQUIPMENT
Some of the systems in the previous figurescontained cryptographic equipment. Cryptographicequipment is only one of a number of the elements thatmake up a secure communications system. Thoughseveral different types of on-line cryptoequipments arein use throughout the naval communications system,they are all designed to perform the same basic function:to encipher and decipher teleprinter or digital datasignals.
Simply stated, the transmitter accepts a “plain text”teleprinter or data signal containing classified materialfrom the classified patch panel (red). It then adds a“key,” and relays the sum as “cipher text,” or anenciphered signal. A key is a sequence of randombinary bits used to initially set and periodically changepermutations in cryptoequipment for decryptingelectronic signals.
Following this encryption, the signal is fed to theunclassified patch panel (black). Here, it is patcheddirectly to the frequency-shift keyer or the multiplexequipment of the transmitter and converted into anaudio signal. The audio signal, now in a form suitablefor transmission, is routed to the transmitter via thetransmitter transfer switchboard.
On the receive side, the signal flow is quite similarto the send side in reverse order. The receiver acceptsthe enciphered signal from the black patch panel andgenerates a key to match the one generated by thetransmitter. The receiver then subtracts the key from thecipher text input (which restores the plaintextteleprinter or data signal). Finally, it passes the signalon to the red patch panel for dissemination to theterminal equipment for printout.
For further information and operator instructionson a specific type of cryptoequipment, refer to theapplicable KAO publication.
AN/UCC-1 TELEGRAPH MULTIPLEXTERMINAL
Because of the traffic volume handled, many shipsand shore stations require multiple teleprinter circuitson one sideband circuit. The method for increasingcircuits on a sideband is called multiplexing. The Navyuses two multiplexing techniques in communications:time division and frequency division. The AN/UCC-1Telegraph Multiplex Terminal uses the frequency-division technique.
The AN/UCC-1 Telegraph Multiplex Terminal(figure 1-8) is a frequency-division multiplexedterminal equipment for use with single-sideband (SSB)or double-sideband (DSB) radio circuits, audio-frequency wire lines, or microwave circuits. TheAN/UCC-1 is normally used afloat on a multichannelship-shore full-period termination (discussed later).
The following is an overview of how the AN/UCC-1 works:
At the transmitting station, the signals from theindividual circuits, known as channels, aremultiplexed into one composite signal fortransmission. The transmission with themultiplexed channels is known as a tonepackage.
At the receiving station, the composite signal(tone package) is demultiplexed (separated) intoindividual signals and distributed to separateteleprinters, as required.
The terminal can operate in a nondiversity, audio-frequency diversity, space diversity, or radio-frequencydiversity mode. Because of this versatility, the terminalis installed in various configurations throughout theNavy.
Each electrical equipment cabinet houses onecontrol attenuator (right side) and up to a maximum ofeight frequency-shift keyers or eight frequency-shiftconverters.
Since the control attenuator, keyers, and convertersare solid-state, integrated-circuit, plug-in modules, thenumber of channels can be varied by increasing ordecreasing the total number of modules. Dependingupon the number of modules and the configurationused, the terminal can provide up to 16 narrowbandchannels.
For example, if the terminal has keyers in the topcabinet and converters in the bottom cabinet, the systemcould transmit different information on eight channels.Each keyer would represent a channel on the transmitside and each converter, a channel on the receive side.
Each frequency-shift keyer accepts a dc telegraphsignal input from an external loop and generates theappropriate audio-frequency mark and spacefrequency-shift output. The individual keyers eachcontain two oscillators operating on opposite sides of acenter frequency. For example, in figure 1-9, the centerfrequency of keyer number one is 425 Hz, the markfrequency is 382.5 Hz, and the space frequency is 467.5
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Figure 1-9.—Keying frequencies of the AN/UCC-1.
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Hz. These audio-frequency mark and space outputs arereferred to as “tones”; thus keyer one has a one-channel,two-tone output.
A dc telegraph signal on channel 1 determineswhich frequency is gated from the keyer to the groupattenuator. Each channel works in the same way. Itaccepts a dc signal of marks and spaces from selectedequipments patched to that channel. It then provides anaudio output of either a mark or space frequency-shiftedtone, according to the input.
The individual tones are combined at the controlattenuator into a composite tone package. The controlattenuator ensures that the composite tones remain at aconstant amplitude for modulating the transmitter.
At the receiving end of the communications link,the AN/UCC-1 reverses the process performed at thetransmitting end. The AN/UCC-1 applies theinformation on each of the channels to the selectedequipments connected to the converter of that charnel.
In a frequency-division circuit configuration, eachchannel has an input from a different teleprinter. If achannel fades at a particular frequency, the informationon the channel could be lost or distorted. In such cases,the information may need to be retransmitted. To helpprevent this, diversity switches that will permit the useof more than one channel for the same intelligence areavailable.
In switch position 1, only the normal channel isused. In position 2, a single teleprinter signal providesinput for two adjoining keyers. In position 4, fourkeyers are connected to the same input loop. Theswitches on all keyers must be in the same position toprovide the same intelligence to the selectedcombination of channels.
When identical intelligence untransmitted on two orfour channels, it is less likely to be lost or distorted. Atthe receiving end, two or four corresponding convertersmay be used; the converter having the stronger signal
input automatically provides the signal to be used by thereceiving teleprinter.
In the fleet broadcast multiplexing system, whichconsists of 16 channels, 2 channels normally carry thesame intelligence. This process is called twinning.
Another method of multiplexing mentioned earlieris time-division multiplexing (TDM). In this method, adigital input is fed to a TDM unit. Here, it ismultiplexed into a composite intelligence stream fortransmission. The output is sent to an end user, where itis broken into its original individual inputs.
However, instead of splitting the frequencies as infrequency-division multiplexing (FDM), TDM sharestime. Each input uses the full bandwidth of the assignedfrequency but is assigned unique time portions of thesystem. Figure 1-10 illustrates the front panel of a full-duplex time-diversity modem.
SHIP-SHORE CIRCUITS
As we mentioned earlier, the fleet broadcast is theprimary means for delivering messages to afloatcommands. This section discusses a few of the othertypes of circuits by which a ship can transmit itsmessage traffic ashore or to other ships for delivery orrelay.
SHIP-SHORE CIRCUIT MODES OFOPERATION
There are three methods of operatingcommunications circuits: duplex, simplex, andsemiduplex. The mode of operation at any given timedepends upon equipment and frequency availability.
Duplex
Duplex describes a communications circuitdesigned to transmit and receive simultaneously. Insuch operations, each station transmits on a differentfrequency and both stations transmit concurrently. Both
Figure 1-10.—Full-duplex time-diversity modem.
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stations are required to keep transmitters on the air at alltimes and to send a phasing signal at the request of thedistant end. Figure 1-11 shows a diagram of a UHF/HFfull-duplex FSK (frequency-shift keying) single-channel teleprinter relay circuit.
There are two types of duplex operation: fullduplex and half duplex. Full duplex (FDX) refers to acommunications system or equipment capable oftransmitting simultaneously in two directions. Halfduplex (HDX) pertains to a transmission over a circuitcapable of transmitting in either direction, but only onedirection at a time.
Small ships traveling in company normally useduplex in a task group common net in which theyterminate with a larger ship that is serving as net control.The net control ship provides the ship-shore relayservices. Ships traveling independently can use this
system for anon-call ship-shore termination to transmittheir outgoing messages.
Simplex
Simplex is a method of operation that provides asingle channel or frequency on which information canbe exchanged (figure 1-12). Simplex communicationsoperation is normally reserved for UHF and those shipsthat do not have sufficient equipment for duplexoperation. In some cases, a simplex circuit can beestablished when equipment casualties occur.
Where no HF simplex frequency is indicated orguarded, ships requiring a simplex ship-shore circuitmust call on a duplex ship send frequency. The shipmust state “SIMPLEX” in the call-up, indicating thatthe ship cannot transmit and receive simultaneously.
Figure 1-11.—UHF/HF full-duplex FSK single-channelteleprinter relay circuit.
Figure 1-12.—UHF/HF netted simplex FSK teleprinter relaycircuit.
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When a ship requests simplex operation on duplexcircuits, the shore station may be required to shifttransmitters prior to acknowledging call-up. If no replyis received within 45 seconds, the ship should repeat thecall-up procedures. If a third attempt is required, theship should check equipment to ensure properoperation.
Semiduplex
Semiduplex communications circuits, usedprimarily on task force/task group/ORESTES, are acombination of the simplex and duplex modes. Allstations except the net control station (NECOS)transmit and receive on the same frequency. TheNECOS transmits and is received on a secondfrequency. The NECOS may transmit continuously,whereas all other stations must transmit in accordancewith simplex procedures.
UHF/HF RELAY
The UHF/HF relay method permits long-range,uninterrupted communications during periods ofhazardous electromagnetic radiation (HERO). Figure1-13 shows a block diagram of a UHF/HF voice relaycircuit.
Modern radio and radar transmitting equipmentsproduce high-intensity RF fields. It is possible for RFenergy to enter an ordnance item through a hole or crackin its skin or to be conducted into it by firing leads,wires, and the like. Here is an example of HERO. Anaircraft carrier is arming aircraft on board. Duringarming operations, all HF transmitters must be securedto prevent possible detonation of the ordnance. Tomaintain its ship-shore communications, the carriertransmits to a relay ship via a UHF circuit. The relayingship then retransmits the signal on a HF circuit to aterminated NAVCOMTELSTA. On-l ine
Figure 1-13.—UHF/HF voice relay circuit.
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radioteleprinters can be relayed, as well as voice, usingthis circuit.
SECURE VOICE WORLDWIDE VOICENETWORK
The secure voice network is designed to providered-time voice communications between forces afloatand operational commanders ashore, using either HF orsatellite connectivity. This system is commonlyreferred to as GPS Worldwide HICOMM.
System Control
This system consists of three separate networks.Each network has an area control station controlled by aFLTCINC; either CINCLANTFLT, CINCPACFLT, orCINCUSNAVEUR. Each area has subarea controlstations determined by each FLTCINC to ensureworldwide coverage.
Satellite System Control
The secure voice system, using satellitetransmissions, has limited shore access points at thefour COMMAREA master s ta t ions andNAVCOMTELSTA Stockton, California. These sitesserve as the interface channel to both the wideband andnarrowband voice systems in order to extend calls tooperational commanders ashore.
Net Membership
If a ship, aircraft, or shore station needs to enter thesecure voice network, it must be prepared to do so withminimum time delay. Units desiring to enter the net on atemporary basis must specify the length of time andpurpose for entering the net. They must also obtainpermission from the appropriate control station. Thearea net control station (NECOS) is responsible forcompleting all calls originating from senior commandsto all commands, ships, or aircraft within the specificFLTCINC’s net. Certain rules must be observed whenon the secure voice net, as follows:
HF transmitter tuning is prohibited on securevoice. Transmitters must be calibrated andpretuned on a dummy load. Final tuning may beaccomplished during live transmissions.
All stations must maintain a continuous log onsecure voice. The actual time of significanttransmissions must be entered into the log.When available, recording devices must be usedin lieu of a paper log.
The net operates as a free net unless otherwisedirected by the area FLTCINC. NECOS retainsthe prerogative of exercising control over alltransmissions to ensure proper circuit discipline.
FULL-PERIOD TERMINATIONS
Full-period terminations are dedicated circuits thatprovide communications between shore stations andafloat commands. These terminations requireallocation of limited NCTAMS/NCTS assets.Therefore, the criteria for requesting, approving, andestablishing such circuits is necessarily strict.
Termination Requests
Afloat commands and individual units can requestfull-period termination during special operations,deployments, intensive training periods, or exerciseswhen primary ship-shore circuits will not suffice.Commands should request full-period terminationsonly when traffic volume exceeds speed and capabilityof ship-shore circuits and when operational sensitivityrequires circuit discreetness or effective command andcontrol necessitates dedicated circuits.
T h e h e a v y d e m a n d s p l a c e d u p o nNCTAMS/NCTSs for full-period terminations requiremaximum cooperation between shore stations andafloat commanders prior to and during an operation.Ships having a need for a full-period termination, eitherfor training or operational requirements, must submit atermination request to the COMMAREA master stationat least 48 hours prior to activation time.
Emergency commitments or a command directivemay necessitate a lead time of less than 48 hours.Whenever possible, however, the 2-day limit must behonored to achieve maximum preparation andcoordination. NTP 4 gives details of requiredinformation that must be included in a terminationrequest message.
The COMMAREA master station will assign ashore station for a ship’s termination circuit. Once theshore station has been assigned, both the ship and thestation may begin coordination to identify specificequipment keylists and frequencies needed to effecttermination. The shore station will also act as NECOS.Two hours prior to the scheduled termination, the shorestation can coordinate with the ship by telephone, localcircuitry, or by primary ship-shore.
When the ship shifts terminations, the securing ofthe current termination and the establishment of a new
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termination should coincide with a broadcast shiftwhenever possible. The ship must submit aCOMMSHIFT message.
Termination Types
There are six types of full-period terminations, asfollows:
l
l
l
l
l
l
Single-channel radioteleprinter using eitherradio path or landline transmission media;
Single-channel low-data-rate satellite accessusing satellite transmission media;
CUDIXS special satellite access forNAVMACS-equipped ships using satellitetransmission media;
Multichannel radioteleprinter using either radiopath or landline transmission media;
Multichannel radioteleprinter using SHFsatellite transmission media; and
Tactical intelligence (TACINTEL) access forTACINTEL-equipped ships using satellitetransmission media.
Equipment Tests
To ensure that circuit equipment is in peakoperational condition, complete system back-to-backoff-the-air tests must be completed 24 hours prior totermination activations. Check cryptoequipment back-to-back after daily crypto changes and prior to puttingcircuits into service.
An aggressive PMS and quality monitoringprogram is essential. When checking equipment, lookfor power levels, scorch or burn marks, properoperation of interlocks, and cleanliness. When cleaningand inspecting antennas, look for cracks, chips, orblistering of insulators. Also check for deterioration,loose connectors, and correct insulator resistance.
COMMSPOT Reports
COMMSPOT reports will be submitted by allships, including nonterminated units, any time unusualcommunication difficulties are encountered. Ships willsubmit the COMMSPOT to the terminatingcommunications station. Timely submission ofCOMMSPOT reports is necessary to minimize furtherdeterioration of the situation.
Rules and general instructions for preparingJINTACCS formatted COMMSPOT reports are foundin the Joint Reporting System (General Purpose Re-ports), NWP 1-03, Supp-1 (formerly NWP 10-1-13).
PRIMARY SHIP-SHORE CIRCUITS
Primary ship-shore (PRI S/S) circuits are encryptedFSK/PSK teleprinter nets that permit ships to transmitmessages for delivery ashore. This service is availableto units that do not maintain a full-period ship-shoretermination. Navy tactical UHF satellites or theHF/UHF spectrum may be used to conduct ship-shorecircuit operations. Ships may use this circuit forcoordinating and establishing a full-period terminationwith the shore station.
T h e f r e q u e n c i e s f o r N C T A M S a n dNAVCOMTELSTAS that guard primary fleet ship-shore circuits are listed in applicable CIBs distributedby the COMMAREA master stations. Thesefrequencies are subject to change by the cognizantFLTCINC or by the NCTAMS.
OVER-THE-AIR TRANSFER (OTAT) ANDOVER-THE-AIR REKEY (OTAR)
There are significant vulnerabilities associated withthe handling of paper cryptographic material. Soundapplication of over-the-air transfer/rekey(OTAT/OTAR) procedures and techniques can reducethe amount of paper keying material required andreduce the potential for compromise. These proceduresand techniques are contained in the NAG-16BProcedures Manual for Over-the-Air Transfer (OTAT)and Over-the-Air Rekey (OTAR).
OTAT/OTAR also makes the transfer of keyingmaterial more responsive to rapidly changingoperational requirements. The use of NAG-16B wasdeveloped and verified by extensive use duringoperation Desert Shield/Storm. The specifiedprocedures served as an effective vehicle fortransferring keying to satisfy rapidly changing joint andNavy requirements. Expanded definitions, generalprocedures, and equipments are found in NAG-16B.
DISTRESS COMMUNICATIONS
Special methods of communication have beendeveloped to use in times of distress and to promotesafety at sea and in the air. Distress message traffic isbest described as all communications relating to theimmediate assistance required by a mobile station in
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distress. Distress traffic has priority over all othertraffic. All U.S. Navy communicators must be familiarwith distress signals to properly evaluate their meaningsand to take appropriate action when necessary.
If a ship becomes involved in a distress situation,communications personnel should send distressmessages on normal operating encrypted circuits. If theneed for assistance outweighs security considerations,the ship’s commanding officer may authorize thetransmission of an unclassified distress message on oneof the national or international distress frequencies.
When a ship in distress is traveling in company withother ships, the ship in distress will transmit the distressmessage to the officer in tactical command (OTC), whowill take appropriate action.
DISTRESS FREQUENCIES
Several frequencies in different bands aredesignated for the transmission of distress, urgency,safety, or search and rescue (SAR) messages. Thefollowing frequencies have been designated for useduring a distress or emergency situation:
500 kHz— International CW/MCW distress andcalling;
2182 kHz— International voice distress, safety,and calling;
8364 kHz— International CW/MCW lifeboat,life raft, and survival craft;
121.5 MHz— International voice aeronauticalemergency;
156.8 MHz— FM United States voice distressand international voice safety and calling; and
243.0 MHz— Joint/combined military voiceaeronautical emergency and internationalsurvival craft.
During SAR missions, the following frequenciesare authorized for use:
3023.5 and 5680 kHz— International SARfrequencies for the use of all mobile units at thescene of a search. Also for use of shore stationscommunicating with aircraft proceeding to orfrom the scene of the search. CW and voice areauthorized.
123.1 MHz— International worldwide voiceSAR use.
138.78 MHz— U.S. military voice SAR on-the-scene use. This frequency is also used fordirection finding (DF).
172.5 MHz— U.S. Navy emergency sonobouycommunications and homing use. Thisfrequency is monitored by all U.S. Navy ASWaircraft assigned to a SAR mission.
282.8 MHz— Joint/combined on-the-scenevoice and DF frequency used throughout NATO.
The control of distress message traffic on anydesignated frequency is the responsibility of the stationin distress. However, this station may delegate itsresponsibility to another station on the frequency.
Distress Watches
Navy units at sea have always maintained listeningwatches on distress frequencies. Communicationwatch requirements vary according to the operationalmission of the ship and available equipment assets.Ships in company normally divide distress watchrequirements among the group.
STATUS BOARD
The technical control of the shore station that isNECOS for fill-period terminations and PRI S/Scircuits must maintain a status board. The status boardshould indicate, as a minimum, all systems/circuits thatare active, tuned in, or in a standby status. It should alsoindicate all inoperative equipment. The watchsupervisors must verify the accuracy of the informationcontained on the status board at watch turnover andupdate while on watch. The status board must show thefollowing minimum information for active and standbycircuits:
Functional title of circuit;
Frequency(ies), both send/receive, if fill-duplexoperation is used;
Circuit designator, from communication plan;
Transmitter and receiver designations;
For shore stations, keying line designations;
Terminal equipment designation (for example,R-2368/URR #l);
Cryptoequipment, keying material, and restarttime;
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Figure 1-14.—AN/SSQ-88 Quality Monitoring Set and RCS interface.
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Figure 1-15.—AN/SSQ-88 equipment configuration.
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Operating position or remote control unitdesignation; and
Remarks, as appropriate.
QUALITY MONITORING
In recent years, the volume of communications hasincreased dramatically. This rapid expansion has led tothe installation of increasingly sophisticatedequipment. Such factors as frequency accuracy, dcdistortion, inter-modulation distortion (IMD), anddistribution levels are critical to the operation ofcommunications systems.
Satisfactory operation of these systems demandsprecise initial line-up and subsequent monitoring.System degradation is often caused by many smallcontributing factors that, when combined, render thesystem unusable. Simply looking at the page printer orlistening to the signal is inadequate.
Simply stated, quality monitoring is theperformance of scheduled, logical checks that willensure continuous, optimum performance and, in manycases, prevent outages before they occur. Somecommunications personnel quite often fail to realize thebenefits of quality monitoring. An attitude developsthat questions the need for quality monitoring. Theresult of this incorrect attitude is that circuits are eitherUP or DOWN. Personnel with this attitude perform noquality monitoring when the circuits are UP and are,therefore, forced to treat each outage as if it were aunique occurrence.
With no precise information concerning the trend ofthe system’s performance, personnel must jump fromone assumed probable cause to another assumedprobable cause, while valuable circuit time is lost. Aship with an aggressive quality monitoring programusually has personnel who are thoroughly familiar withall installed communications systems.
QUALITY MONITORING PROGRAM
The primary function of the quality monitoringprogram is the direct measurement of signal qualitycharacteristics, including:
Dc distortion;
Audio distribution level;
Frequency accuracy of RF signals;
Spectrum analysis; and
Loop current.
These measurements are broad categories and can bebroken down to specific tests for specific systems.
Quality Monitoring System
Figure 1-14 is a diagram of a quality monitoringsystem and RCS interface. The system was designed toprovide a means of monitoring and evaluatingperformance of any communications system used byforces afloat.
The monitoring system is a grouping of specific testequipments into a console designated as the AN/SSQ-88 Quality Monitoring Set. The set contains equipmentfor measuring and analyzing signals sampled by sensorsinstalled in each communications circuit interface. Thesystem should be operated only by personnel withsufficient knowledge to analyze the signals beingtransmitted and received via the ship’s circuits,including individual channels of the multichannelcircuits.
The console configuration shown in figure 1-15may not be compatible with all ships; however, mostships can use equivalent test equipment to establish aquality monitoring test system.
SUMMARY
Your commanding officer must be able tocommunicate with ships and shore stations to maintaineffective command and control of the situation at hand.Communications are, and always will be, the “voice ofcommand.” In the age of nuclear weapons, guidedmissiles, supersonic aircraft, and high-speed ships andsubmarines, top performance is required of our fleetcommunicators. You, as a Radioman, and yourequipment must always be in constant readiness to meetthis formidable challenge.
Distress communications are methods that havebeen developed for use in times of distress. Theyindicate the need for immediate assistance and havepriority over all other traffic. Various publications andlocal instructions will assist you in carrying out yourrequired responses to these situations.
Communication systems are periodically tested toensure that they operate efficiently and accurately. Thecombined tests, checks, and measurements helpdetermine the condition of systems, subsystems, andindividual equipments. Tests and measurements ofcommunication systems and equipments range from thevery simple to the very complex.
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CHAPTER 2
SATELLITES AND ANTENNAS
LEARNING OBJECTIVES
Upon completing this chapter, you should be able to do the following:
Identify the theory relating to satellites.
Calculate azimuth and elevation, using plotting guides.
Identify the types, basic system and fleet broadcast subsystem equipment ofcommunication satellites.
Identify the characteristics of antennas and antenna selections.
Identify the types of antennas.
Explain how the distribution systems interface with antenna assignment andselections.
Identify the procedures for setting up antenna couplers, multicouplers,transmitters, and transceivers.
Explain how the patch panel is used in conjunction with the equipment.
Identify the procedures for raising and lowering antennas.
Determine the optimum reception of a directional antenna by rotation,alignment, and tuning.
Identify safety precautions that should be observed when working onantennas.
Satellite communication (SATCOM) systems SATCOMM ANTENNAS
satisfy many military communications requirements The antennas shown in figures 2-1 and 2-2 are usedwith reliable, high-capacity, secure, and cost-effectivetelecommunications. Satellites provide a solution to theproblem of communicating with highly mobile forcesdeployed worldwide. Satellites also provide analternative to large, fixed ground installations. Theyprovide almost instantaneous military communicationsthroughout the world at all but the highest latitudes(above 700).
for satellite communications. The OE-82C/WSC-1(V)antenna (figure 2-1) is used with the AN/WSC-3transceiver and designed primarily for shipboardinstallation. Depending upon requirements, one or twoantennas may be installed to provide a view of thesatellites at all times. The antenna is attached to apedestal. This permits the antenna to rotate so that it isalways in view of the satellite. The frequency band forreceiving is 248 to 272 MHz; the band for transmittingis 292 to 312 MHz.
2-1
Figure 2-1.—OE-82C/WSC-1(V) antenna group.
Figure 2-2.—AS-2815/SSR-1 antenna physical configuration.
The AN/SRR-1 receiver system consists of up tofour AS-2815/SSR- 1 antennas (figure 2-2) with anamplifier-converter, AM-6534/SSR-1, for eachantenna. The antennas are used to receive satellite fleetbroadcasts at frequencies of 240 to 315 MHz. Theantenna and converters are mounted above deck so thatat least one antenna is always in view of the satellite.
The newer satellite systems use the SHF band. Oneof the major advantages of these systems is that they usea very small parabolic antenna measuring only 12inches in diameter.
A satellite antenna must be pointed at the satellite tocommunicate. We must first determine the azimuth(AZ) and elevation (EL) angles from a fixed location.Figure 2-3 illustrates how these angles are derived,
2-2
using a pointing guide called the Equatorial SatelliteAntenna Pointing Guide. This guide is normallyavailable through the Navy Supply System.
The antenna pointing guide is a clear plasticoverlay, which slides across a stationary map. Itindicates AZ and EL angles in degrees to the satellite.The values obtained are useful to the operator in settingup the antenna control unit of a satellite system.
To use the guide, follow these procedures:
Center the overlay directly over the desiredsatellite position on the stationary map.
Mark the latitude and longitude of the ship on theplastic antenna pointing guide with a greasepencil.
Determine the approximate azimuth angle fromthe ship to the satellite.
Locate the closest dotted line radiating outwardfrom the center of the graph on the overlay inrelation to the grease dot representing the ship’s
location. This dotted line represents degrees ofazimuth as printed on the end of the line. Someapproximation will be required for ship positionsnot falling on the dotted line.
Determine the degrees of elevation by locatingthe solid concentric line closest to the ship’smarked position. Again, approximation will berequired for positions not falling directly on thesolid elevation line. Degrees of elevation aremarked on each concentric line.
Example: Assume that your ship is located at30° north and 70° west. You want to accessFLTSAT 8 at 23° west. When we apply theprocedures discussed above, we can see theexample indicates an azimuth value of 115° andan elevation angle of 30°.
TYPES OF SATELLITES
Three types of communications satellites are in useby the U.S. Navy today. They are GAPFILLER, FleetSatellite Communication (FLTSATCOM), and Leased
Figure 2-3.—Equatorial Satellite Antenna Pointing Guide.
2-3
Satellite (LEASAT) (figure 2-4). These satellites are ingeosynchronous orbit over the continental UnitedStates and the Atlantic, Pacific, and Indian oceans.Each satellite is described in the following paragraphs.
GAPFILLER
In 1976, three satellites, called MARISAT, wereplaced into orbit over the Atlantic, Pacific, and Indianoceans. Each satellite had three UHF channels formilitary use, one wideband 500-kHz channel, and twonarrowband 25-kHz channels.
The Navy leased the UHF section of each satellitefor communications purposes. To distinguish thespecial management and control functions for
communications on these UHF channels, the Navy gavethe name GAPFILLER to the leased satellite assets.
GAPFILLER was intended to fill the need for acontinuing satellite communications capability insupport of naval tactical operations until the Navyachieved a fully operable Fleet SatelliteCommunications (FLTSATCOM) system.
The GAPFILLER satellite over the Indian Ocean isthe only one still being used by the U.S. Navy. The othertwo GAPFILLER satellites were replaced by LEASAT.The active GAPFILLER satellite will also be replacedby LEASAT as it reaches the end of its operational life.
Within the 500-kHz band, transponders provide 20individual 25-kHz low- and high-data-ratecommunications channels for 75 baud ship-shore
Figure 2-4.—GAPFILLER, FLTSATCOM, and LEASAT satellites.
2 - 4
communications and for the automated informationexchange systems. The UHF receiver separates thereceive band (302 to 312 MHz) from the transmit band(248 to 258 MHz).
The receiver translates the received carriers tointermediate frequencies (IFs) in the 20-MHz range andseparates them into one of three channels. One charnelhas a 500-kHz bandwidth, and two have a bandwidth of25 kHz each. The signals are filtered, hard limited,amplified to an intermediate level, and up-converted tothe transmit frequency. Each channel is then amplifiedby one of three high-power transmitters.
GAPFILLER also supports the FLTSATCOMsystem secure voice system and the fleet broadcast inthe UHF range. The GAPFILLER communicationssubsystem will eventually be replaced by theFLTSATCOM system.
FLTSATCOM
There are four FLTSATCOM satellites in service.These satellites are positioned at 100° W, 72.5° E, 23°W, and 172° E longitudes. They serve the Third, Sixth,Second, and Seventh fleets and the Indian Ocean battlegroups. These four satellites provide worldwide
coverage between 70° N and 70° S latitudes (figure2-5).
Each FLTSATCOM satellite has a 23-RF-channelcapability. These include 10 25-kHz channels, 12 5-kHz channels, and 1 500-kHz channel. The 500-kHzand the 10 25-kHz channels are reserved for Navy use.Of the 10 25-kHz channels, channel 1 is used for thefleet broadcast. All charnels use SHF for the uplinktransmission. SHF is translated to UHF for thedownlink transmission.
There is a separate UHF downlink transmitter foreach channel. Each of the 23 channels has 3 differentfrequency plans in which the uplink or downlink may betransmitted. This capability precludes interferencewhere satellite coverage overlaps.
LEASAT
The latest generation of Navy communicationssatellites is leased; hence, the program name LEASAT.As we mentioned earlier, these satellites replaced 2 ofthe 3 GAPFILLER satellites and augment theFLTSATCOM satellites.
CONUS LEASAT (L-3) is positioned at 105° Wlongitude, LANT LEASAT (L-1) is positioned at
Figure 2-5.—FLTSATCOM coverage areas,
2-5
15° W longitude, and 10 LEASAT (L-2) is positionedat 72.5° E longitude (figure 2-6).
Each LEASAT provides 13 communicationschannels using 9 transmitters. There are 7 25-kHz UHFdownlink channels, 1 500-kHz wideband channel, and5 5-kHz channels. The 500-kHz channel and the 725-kHz channels are leased by the Navy. One of the 725-kHz UHF downlink channels is the downlink for theFleet Satellite Broadcast.
The broadcast uplink is SHF, with translation toUHF taking place in the satellite. The remaining 625-kHz channels function as direct-relay channels withseveral repeaters. Currently, the LEASAT channelsprovide for the following subsystems:
Channel 1 for Fleet Satellite Broadcasttransmissions;
1 25-kHz channel for SSIXS communications;
1 25-kHz channel for ASWIXS com-munications; and
2 25-kHz channels for subsystems that transmitor receive via DAMA (Demand AssignedM u l t i p l e A c c e s s ) ( f o r e x a m p l e ,CUDIXS/NAVMACS, TACINTEL, and securevoice).
PHASE IV
Operations Desert Shield/Desert Storm reinforcedthe requirement for and greatly accelerated theintroduction of SHF SATCOM capability on aircraftcarriers and amphibious flagships to satisfy minimumtactical command and control (C2), intelligence andwarfighting communications requirements whileimproving Joint and NATO/Allied communicationsinteroperability. To meet the urgent operationalrequirement, the U.S. Navy obtained and modified U.S.Air Force AN/TSC-93B Ground Mobile Forces (GMF)SHF SATCOM vans for installation on aircraft carriersand amphibious flagships deploying to the PersianGulf. The modified vans were coupled with theAN/WSC-6(V) standard U.S. Navy SHF stabilizedantenna system, the SURTASS modem, 2 low speedtime division multiplexer (LSTDMs), and additional
Figure 2-6.—LEASAT coverage areas.
2-6
patch panels. The modified SATCOM terminals weredesignated “QUICKSAT”. The initial introduction ofthese terminals into the fleet officially marked thebeginning of Phase I of the U.S. Navy’s SHF SATCOMfielding plan (with everything prior being referred to asPhase 0) and provided an immediate operationalcapability.
Phase II of the U.S. Navy’s SHF fielding plan,which commenced in FY 94, will replace QUICKSATterminals on aircraft carriers with an AN/WSC-6(V)4terminal. The U.S. Navy will also deploy an SHFDemand Assigned Multiple Access (DAMA) modem.This phase replaces the QUICKSAT terminals onaircraft carriers, and adds SHF SATCOM capabilities tomore ships.
Commencing in FY97, Phase III will deploy thenext AN/WSC-6 variant. The new terminal will be amodem, modular, open architecture terminal capable ofproviding a full spectrum of SHF SATCOM servicesand greatly expand the number of installations.
The system configuration that supports Navy SHFSATCOM consists of an SHF RF terminal andsupporting baseband equipment. The RF terminals forshipboard use are the AN/WSC-6(V) or AN/TSC-93B(MOD) “QUICKSAT” terminal. The terminals processand convert the RF signal transmitted to or receivedfrom the space segment. The transmit frequency rangeis 7.9 to 8.4 GHz, and the receive range is 7.25 to 7.75GHz. The OM-55(V)/USC AJ modems, 1105A/1106time division multiple access (TDMA)/DAMA modem,and the CQM-248A (phase shift keying (PSK)modems) are deployed on shipboard platforms.
The AN/WSC-6(V) and QUICKSAT configuredterminals are compatible with present and future DSCSSHF satellite ground terminals and consist of anantenna group, radio set group and modem group. Theantenna group is configured as either a dual or singleantenna system. The AN/WSC-6(V)1, with the MD-1030A(V) modem, is used on SURTASS shipsequipped with a single antenna. The AN/WSC-6(V)2,with the OM-55(V)/USC, Frequency Division MultipleAccess (FDMA) or TDMA/DAMA modems, is used onboth flag and flag-capable platforms and is configuredwith either a single or dual antenna. The QUICKSATterminal is configured with an FDMA modem, single ordual antenna, and deployed on selected aircraft carriersand amphibious flagships. The AN/WSC-6(V) andQUICKSAT terminals automatically track the selectedsatellite, while simultaneously transmitting andreceiving. An antenna control unit commands theantenna to search for tracking (beacon) signals from the
satellite. Upon satellite acquisition, tracking isaccomplished automatically.
BASIC SATCOM SYSTEM
A satellite communications system relays radiotransmissions between Earth terminals. There are twotypes of communications satellites: active and passive.An active satellite acts as a repeater. It amplifies signalsreceived and then retransmits them back to Earth. Thisincreases the signal strength at the receiving terminalcompared to that available from a passive satellite. Apassive satellite, on the other hand, merely reflects radiosignals back to Earth.
A typical operational link involves an activesatellite and two Earth terminals. One termonaltransmits to the satellite on the uplink frequency. Thesatellite amplifies the signal, translates it to thedownlink frequency, and then transmits it back to Earth,where the signal is picked up by the receiving terminal.Figure 2-7 illustrates the basic concept of satellitecommunications with several different Earth terminals.
The basic design of a satellite communicationssystem depends a great deal on the parameters of thesatellite orbit. Generally, an orbit is either elliptical orcircular. Its inclination is referred to as inclined, polar,or equatorial. A special type of orbit is a synchronousorbit in which the period of the orbit is the same as thatof the Earth’s.
Two basic components make up a satellitecommunications system. The first is an installedcommunications receiver and transmitter. The secondis two Earth terminals equipped to transmit and receivesignals from the satellite. The design of the overallsystem determines the complexity of the componentsand the manner in which the system operates.
The U.S. Navy UHF/SHF/EHF combinedcommunications solution allows each system to provideunique contributions to the overall navalcommunications needs.
The SHF spectrum is a highly desirable SATCOMmedium because it possesses characteristics absent inlower frequency bands: wide operating bandwidth,narrow uplink beamwidth, low susceptibility toscintillation, anti-jam (AJ), and high data rates.Recognizing these characteristics, the U.S. Navydeveloped and installed shipboard SHF terminals.These attributes are discussed in the followingparagraphs.
2-7
Figure 2-7.—Satellite communications systems.
Wide operating bandwidth permits highinformation transfer rates and facilitates spreadspectrum modulation techniques. Spread spectrummodulation is a particularly valuable technique forlessening the effects of enemy jamming. Althoughwide bandwidth permits both high information transferrates and AJ capabilities when using the OM-55(V)/USC modem, it may not permit bothsimultaneously in the presence of jamming. Therefore,high information transfer rates will be significantlyreduced when jamming is encountered, permitting onlycertain predetermined critical circuits to be maintained.
Narrow uplink transmission beamwidth provides alow probability of intercept (LPI) capability. An uplinkLPI capability reduces the threat of detection andsubsequent location, but does not in and of itself denyenemy exploitation of those communications ifdetection is achieved. SHF frequencies are rarelyaffected by naturally occurring scintillation, making
SHF SATCOM a particularly reliable form ofcommunications.
A characteristic of SHF, favorable to flagships, isthe ability to communicate critical C4I for the userinformation in the presence of enemy jamming and withdue regard for enemy detection capabilities. SURTASSMilitary Sealift Command Auxiliary General OceanSurveillance (T-AGOS) ships were initially equippedwith SHF SATCOM, taking advantage of the highinformation transfer rate capability and LPIcharacteristics. Because of larger available bandwidths,inherent jam-resistance, and increasing demands onlimited tactical UHF SATCOM resources, additionalapplications for DSCS SHF SATCOM afloat arecontinually being investigated for the Fleet.
The radio group consists of a high power amplifier(HPA) or medium power amplifier (MPA), low noiseamplifier (LNA), up-converter, down-converter, andfrequency standard. For transmit operations, theup-converter translates the modem’s 70 or 700
2-8
Figure 2-8.—AN/SSR-1 receiver system.
megahertz (MHz) intermediate frequency (IF) to thedesired radio frequency. The signal is then passed to theHPA or MPA and amplified to its authorized powerlevel. During receive operations, the LNA amplifies thereceived RF signal and sends it to the tracking converter
for antenna control and the down-converter fortranslation to 70 or 700 MHz IF. This signal is then sentto the modem for conversion to digital data. Systemfrequency stability is provided by a cesium or rubidiumstandard.
FLEET BROADCAST SUBSYSTEMEQUIPMENT
The SATCOM equipments that the Navy uses forthe fleet broadcast include the SATCOM broadcastreceiver (AN/SSR-1), the FLTSATCOM SHFbroadcast transmitter (AN/FSC-79), the standardshipboard transceiver (AN/WSC-3), the shore stationtransceiver (AN/WSC-5), and the basic airbornetransceiver (AN/ARC-143B). A brief description ofthese equipments is given in the next paragraphs.
The AN/SSR-1 is the Navy’s standard SATCOMbroadcast receiver system. This system consists of up tofour AS-2815/SSR-1 antennas with an AM-6534/SSR-1 Amplifier-Converter for each antenna, an MD-900/SSR-1 Combiner-Demodulator, and a TD-1063/SSR-1Demultiplexer (figure 2-8). The antennas are designedto receive transmissions at 240 to 315 MHz. Theantennas and antenna converters are mounted abovedeck so that at least one antenna is always in view of thesatelli te. The combiner-demodulator anddemultiplexer are mounted below deck.
The AN/FSC-79 Fleet Broadcast Terminal (figure2-9) interfaces the communications subsystems and thesatellite. The terminal provides the SHF uplink for the
Figure 2-9.—AN/FSC-79 Fleet Broadcast Terminal.
2-9
FLTSATCOM system and is used in particular tosupport the Navy Fleet Broadcast system. TheAN/FSC-79 operates in the 7- to 8-GHz band and isdesigned for single-channel operation. TheAN/FSC-79 terminal is installed at the fourCOMMAREA master stations andNAVCOMTELSTA Stockton, Calif.
The AN/WSC-3 Transceiver is the standardUHF SATCOM transceiver for both submarine andsurface ships. The AN/WSC-3 is capable ofoperating in either the satellite or line-of-sight(LOS) mode and can be controlled locally orremotely.
The unit is designed for single-channel, half-duplex operations in the 224- to 400-MHZ UHFband. It operates in 25-kHz increments, and has 20preset channels. In the SATCOM mode, theAN/WSC-3 transmits (uplinks) in the 292.2- to311.6-MHz bandwidth and receives (downlinks) in
the 248.5- to 270.1-MHz band. A separate transceiveris required for each baseband or channel use.
The AN/WSC-5 UHF Transceiver (figure 2-10) isthe common UHF RF satellite terminal installed atNAVCOMTELSTAs for the GAPFILLER subsystem.In FLTSATCOM operations, it is used as the commonRF terminal for all subsystems except the FleetSatellite Broadcast (FSB) and the AntisubmarineWarfare information Exchange Subsystem (ASWIXS).The AN/WSC-5 can be used to back up the AN/FSC-79. The AN/WSC-5 transmits in the 248.5- to 312-MHz range and receives in the 248.5- to 270.1-MHzrange.
The AN/ARC-143 UHF Transceiver (figure 2-11)is used for ASWIXS communications and is installedat VP Antisubmarine Warfare Operation Centers andaboard P-3C aircraft. The unit two parts: a transceiverand a radio set control. The AN/ARC-143
Figure 2-10.—AN/WSC-5 UHF Transceiver.
2-10
Figure 2-11.—AN/ARC-143 UHF Transceiver.
can be used to transmit or receive voice or data in the255.0- to 399.99-MHz frequency range.
The systems discussed are only a few of theSATCOM equipments used by the Navy. Some of thereferences listed in Appendix III of this module areexcellent sources for more information on satelliteequipment and systems.
FLEET SATELLITECOMMUNICATIONS SYSTEM AND
SUBSYSTEMS
The Flee t Sa te l l i te Communica t ions(FLTSATCOM) system and subsystems providecommunications links, via satellite, between shorecommands and mobile units. The system includes RFterminals, subscriber subsystems, training,documentation, and logistic support. Within each
satellite, the RF channels available for use have beendistributed between the Navy and the Air Force.
Equipments in support of the FLTSATCOM systemare on ships, submarines, aircraft, and at shore stations.These equipment installations vary in size andcomplexity. Furthermore, with the exception of voicecommunications, the system applies the technology ofprocessor- (computer-) controlled RF links and uses theassistance of processors in message traffic preparationand handling.
Although any part of the FLTSATCOM system canbe operated as a separate module, system integrationprovides connections for message traffic and voicecommunications to DOD communications networks.
A backup capability that can be used in the event ofan outage or equipment failure is provided for bothshore and afloat commands. All subsystems have someform of backup mode, either from backup equipmentand/or systems, facilities, or RF channels. Thiscapability is built in as part of the system design andmay limit the ability of selected FLTSATCOM systemsto process information.
FLEET SATELLITE BROADCAST (FSB)SUBSYSTEM
The Fleet Satellite Broadcast (FSB) subsystem is anexpansion of fleet broadcast transmissions thathistorically have been the central communicationsmedium for operating naval units. The FSB transmitsmessages, weather information, and intelligence data toships. The shore terminal transmits this data on a directSHF signal to a satellite, where the signal is translated toUHF and downlinked. Figure 2-12 shows a standardFSB subsystem configuration.
Figure 2-12.—Fleet Satellite Broadcast subsystem.
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COMMON USER DIGITAL INFORMATIONEXCHANGE SYSTEM (CUDIXS) ANDNAVAL MODULAR AUTOMATEDCOMMUNICATIONS SYSTEM (NAVMACS)
The CUDIXS/NAVMACS combine to form acommunications network that is used to transmitgeneral service (GENSER) message traffic betweenships and shore installations. NAVMACS serves as anautomated shipboard terminal for interfacing withCUDIXS (shore-based) (figure 2-13) and the FleetBroadcast System.
OTHER SPECIALIZED SUBSYSTEMS
The FLTSATCOM system represents a compositeof information exchange subsystems that use thesatellites as a relay for communications. The followingsubsystems satisfy the unique communicationrequirements for each of the different navalcommunities.
Submarine Satellite Information ExchangeSubsystem (SSIXS)
The SSIXS provides a communications system toexchange message traffic between SSBN and SSNsubmarines and shore stations.
Antisubmarine Warfare InformationExchange Subsystem (ASWIXS)
ASWIXS is designed as a communications link forantisubmarine warfare (ASW) operations betweenshore stations and aircraft.
Tactical Data Information Exchange
Subsystem (TADIXS)
TADIXS is a direct communications link betweencommand centers ashore and afloat. TADIXS providesone-way transmission of data link communications.
Secure Voice Subsystem
Figure 2-13.—NAVMACS (V) communications interface.
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The secure voice subsystem is a narrowband UHFlink that enables secure voice communications betweenships. It also allows, connection with wide-area voicenetworks ashore.
Tactical Intelligence (TACINTEL)Subsystem
TACINTEL is specifically designed for specialintelligence communications.
Control Subsystem
The Control subsystem is a communicationsnetwork that facilitates status reporting andmanagement of FLTSATCOM system assets.
Officer in Tactical Command InformationExchange Subsystem (OTCIXS)
OTCIXS is designed as a communications link forbattle group tactical operations.
Teleprinter Subsystem (ORESTES)
ORESTES is an expansion of the existingteleprinter transmission network.
LEASAT TELEMETRY TRACKING ANDCOMMAND SUBSYSTEM
The LEASAT Telemetry Tracking and Commandsubsystem is a joint operation between the U.S. Navyand contractors for controlling LEASATS. Theinstallation of subsystem baseband equipment and RFterminals aboard ships and aircraft is determined bycommunications traffic levels, types ofcommunications, and operational missions.
Since Fleet Satellite Broadcast message traffic is acommon denominator for naval communications, it isreceived by numerous types of ships. In someinstallations, such as large ships, the fleet broadcastreceiver represents one part of the FLTSATCOMequipment suite. A typical configuration on a large shipwould include fleet broadcast, CUDIXS/NAVMACS,secure voice, OTCIXS, TADIXS, teleprinter, andTACINTEL equipment.
The FLTSATCOM subsystems apply some form ofautomated control to the communications beingtransmitted with the exception of the secure voice andcontrol subsystems. This includes message or data linkprocessing before and after transmittal and control ofthe RF network (link control) in which the messages arebeing transmitted. The automation of these functions ishandled by a processor.
Much of the message processing beforetransmission and after receipt is fully automatic anddoes not require operator intervention. The actualmessage or data link transmission is fully automatedand under the control of a processor. Within thelimitations of equipment capability, each subsystemaddresses the unique requirements of the user and theenvironment in which the user operates.
DEMAND ASSIGNED MULTIPLE ACCESS(DAMA)
DAMA was developed to multiplex severalsubsystems or users on one satellite channel. Thisarrangement allows more satellite circuits to use eachUHF satellite channel.
Multiplexing
The number of communications networks beingused is constantly increasing. As a result, all areas of theRF spectrum have become congested. Multiplexing is amethod of increasing the number of transmissionstaking place in the radio spectrum per unit of time.
Multiplexing involves the simultaneoustransmission of a number of intelligible signals usingonly a single transmitting path. As we mentionedearlier, the Navy uses two multiplexing methods: time-division multiplexing (TDM) and frequency-divisionmultiplexing (FDM). We have already discussed FDMwith the AN/UCC-1. Additional informationconcerning both methods can be found in Radio-Frequency Communication Principles, NEETS,Module 17.
A UHF DAMA subsystem, the TD-1271/UMultiplexer, was developed to provide adequatecapacity for the Navy and other DOD users. Thissubsystem was developed to multiplex (increase) thenumber of subsystems, or users, on 1 25-kHz satellitechannel by a factor of 4.
This factor can be further increased by multiples of4 by patching 2 or more TD-1271s together. Thismethod increases the number of satellite circuits perchannel on the UHF satellite communications system.Without this system, each satellite communicationssubsystem would require a separate satellite channel.
Transmission Rates
The DAMA equipment accepts encrypted datastreams from independent baseband sources andcombines them into one continuous serial output data
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stream. DAMA was designed to interface the NavyUHF SATCOM baseband subsystem and the AN/WSC-5 and AN/WSC-3 transceivers.
The TD-1271/U Multiplexer includes a modemintegral to the transceiver. The baseband equipmentinput or output data rate with DAMA equipment can be75, 300, 600, 1,200, 2,400, 4,800, or 16,000 bits persecond (bps). The DAMA transmission rate on thesatellite link (referred to as “burst rate”) can be 2,400,9,600, 19,200, or 32,000 symbols per second.
Circuit Restoral/Coordination
When a termination is lost in either or bothdirections, communications personnel must observespecial guidelines. During marginal or poor periods ofcommunications, the supervisors should assign adedicated operator to the circuit if possible.
When normal circuit restoration procedures areunsuccessful and/or a complete loss of communicationsexists, an IMMEDIATE precedence COMMSPOTmessage should be transmitted (discussed earlier).Every means available must be used to re-establish thecircuit, including messages, support from other ships orNAVCOMTELSTAs, or coordination via DAMA ifavailable.
The guidelines established in NTP 4, CIBs, andlocal SOPs are not intended to suppress individualinitiative in re-establishing lost communications.Circuit restoral is dependent upon timely action, quickdecisions, and the ability of personnel to use any meansavailable to restore communications in the shortestpossible time.
SPECIAL CIRCUITS
During certain communications operations, youmay be required to activate and operate special circuits.Some of the most common special circuits are discussednext.
UHF AUTOCAT/SATCAT/MIDDLEMANRELAY CIRCUITS
Shipboard HERO conditions and emission control(EMCON) restrictions often prohibit transmission ofRF below 30 MHz.
To provide an uninterrupted flow of essentialcommunications without violating HERO and EMCONrestrictions, AUTOCAT, SATCAT, and MIDDLEMANwere developed. With these techniques, the range of
tactical UHF circuits (voice or teleprinter) can beextended by relay of AM UHF transmissions via HF orsatellite. AUTOCAT accomplishes this using a ship;whereas SATCAT uses an airborne platform forautomatically relaying UHF transmissions.MIDDLEMAN requires an operator to copy themessages with subsequent manual retransmission.
The three techniques just discussed use threedifferent types of circuit for reception and relay of UHFtransmissions. These circuits are as follows:
A voice circuit where some units send andreceive on one frequency, and other units sendand receive on any other frequency;
A voice circuit where all units transmit on onefrequency and receive on another frequency; and
A RATT circuit where all units transmit on onefrequency and receive on another frequency.
FLEET FLASH NET
The Fleet Flash Net (FFN) is composed of senioroperational staffs and other designated subscribers. Thepurpose of the FFN is to distribute high-precedence orhighly sensitive traffic among subscribers. A receipt onthe net constitutes firm delivery, and the message neednot be retransmitted over other circuits to receiptingstations. The FFN is explained in more detail in MissionCommunications, NTP 11.
ANTENNA SYSTEMS
Operation of communication equipment over theentire range of the RF spectrum requires many types ofatennnas. You will need to know the basic type ofantennas available to you operationally, theircharacteristics, and their uses, Very often, you, theoperator, can mean the difference between efficient andinefficient communications. You will have a choice ofmany antennas and must select the one most suitable forthe task at hand. Your operational training will acquaintyou with the knowledge necessary to properly use theantennas at your disposal, However, your operationaltraining WILL NOT acquaint you with the WHY ofantennas, in other words, basic antenna theory. Thefollowing topics are intended to familiarize you withbasic antenna terminology, definitions, andcharacteristics.
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ANTENNA CHARACTERISTICS
As you will learn in this section, all antennas exhibitcommon characteristics. The study of antennasinvolves the following terms with which you mustbecome familiar:
Antenna Reciprocity
The ability of an antenna to both transmit andreceive electromagnetic energy is known as itsreciprocity. Antenna reciprocity is possible becauseantenna characteristics are essentially the same forsending and receiving electromagnetic energy.
Even though an antenna can be used to transmit orreceive, it cannot be used for both functions at the sametime. The antenna must be connected to either atransmitter or a receiver.
Antenna Feed Point
Feed point is the point on an antenna where the RFcable is attached. If the RF transmission line is attachedto the base of an antenna, the antenna is end-fed. If theRF transmission line is connected at the center of anantenna, the antenna is mid-fed or center-fed.
Directivity
The directivity of an antenna refers to the width ofthe radiation beam pattern. A directional antennaconcentrates its radiation in a relatively narrow beam. Ifthe beam is narrow in either the horizontal or verticalplane, the antenna will have a high degree of directivityin that plane. An antenna can be highly directive in oneplane only or in both planes, depending upon its use.
In general, we use three terms to describe the type ofdirectional qualities associated with an antenna:omnidirectional, bidirectional, and unidirectional.Omnidirectional antennas radiate and receive equallywell in all directions, except off the ends. Bidirectionalantennas radiate or receive efficiently in only twodirections. Unidirectional antennas radiate or receiveefficiently in only one direction.
Most antennas used in naval communications areeither omnidirectional or unidirectional. Bidirectionalantennas are rarely used. Omnidirectional antennas areused to transmit fleet broadcasts and are used aboardship for medium-to-high frequencies. A parabolic, ordish, antenna (figure 2-14) is an example of aunidirectional antenna. As you can see in the figure, an
Figure 2-14.—Principle of parabolic reflection.
antenna (normally a half wave) is placed at the “focal”point and radiates the signal back into a large reflectingsurface (the dish). The effect is to transmit a verynarrow beam of energy that is essentially unidirectional.Figure 2-15 shows a large, unidirectional parabolicantenna. Directional antennas are commonly used atshore installations.
Wave Polarization
Polarization of a radio wave is a majorconsideration in the efficient transmission andreception of radio signals. If a single-wire antenna is
Figure 2-15.—Unidirectional parabolic antenna.
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used to extract energy from a passing radio wave,maximum signal pickup results when the antenna isplaced physically in the same direction as the electricfield component. For this reason, a vertical antenna isused to receive vertically polarized waves, and ahorizontal antenna is used to receive horizontallypolarized waves.
At lower frequencies, wave polarization remainsfairly constant as it travels through space. At higherfrequencies, the polarization usually varies, sometimesquite rapidly. This is because the wave front splits intoseveral components, and these components followdifferent propagation paths.
When antennas are close to the ground, verticallypolarized radio waves yield a stronger signal close to theEarth than do those that are horizontally polarized.When the transmitting and receiving antennas are atleast one wavelength above the surface, the two types ofpolarization are approximately the same in fieldintensity near the surface of the Earth. When thetransmitting antenna is several wavelengths above thesurface, horizontally polarized waves result in astronger signal close to the Earth than is possible withvertical polarization.
Most shipboard communication antennas arevertically polarized. This type of polarization allowsthe antenna configuration to be more easilyaccommodated in the limited space allocated toshipboard communications installations. Verticalantenna installations often make use of the topsidestructure to support the antenna elements. In somecases, to obtain the required impedance match betweenthe antenna base terminal and transmission line, thestructure acts as part of the antenna.
VHF and UHF antennas used for ship-to-aircraftcommunications use both vertical and circularpolarization. Because aircraft maneuvers cause cross-polarization effects, circularly polarized shipboardantennas frequently offer considerable signalimprovements over vertically polarized antennas.
Circularly polarized antennas are also used for ship-to-satellite communications because these antenntasoffer the same improvement as VHF/UHF ship-to-aircraft communications operations. Except for thehigher altitudes, satellite antenna problems are similarto those experienced with aircraft antenna operations.
Standing Wave Ratio
Another term used in antenna tuning is standingwave ratio (SWR), also called voltage standing wave
ratio (VSWR). A simple definition could be the“relative degree of resonance” achieved with antennatuning. When tuning an antenna, you must understandthe SWR when expressed numerically.
You will hear SWR expressed numerically in nearlyevery tuning procedure. For example, you will hearsuch terms as “three-to-one,” or “two-to-one.” You willsee them written 3:1 SWR, 2:1 SWR, or 1:1 SWR. Thelower the number ratio is, the better the match betweenthe antenna and the transmitter for transmitting RFsignals. For example, a 2:1 SWR is better than a 3:1SWR.
As you approach resonance, you will notice thatyour SWR figure on the front panel meters will begin todrop to a lower numerical value. A good SWR isconsidered to be 3 or below, such as 3:1 or 2:1.Anything over 3, such as 4:1, 5:1, or 6:1 isunsatisfactory. The SWR becomes increasingly criticalas transmitter output is increased. Where a 3:1 SWR issatisfactory with a 500-watt transmitter, a 2:1 SWR maybe considered satisfactory with a 10-kilowatttransmitter.
Most antenna couplers have front panel meters thatshow a readout of the relative SWR achieved viaantenna tuning. Figure 2-16 shows a multicoupler,
Figure 2-16.—AN/SRA-33 antenna multicoupler.
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consisting of four coupling units, with four SWR metersat the top (one for each coupler).
To achieve a perfect standing wave ratio of 1:1would mean that we have succeeded in tuning out allother impedances and that the antenna is matchedperfectly to the transmitted frequency. With such a lowSWR, the antenna would now offer only itscharacteristic impedance. A 1:1 SWR is rarelyachieved, of course. There will always be some powerloss between the transmitter and the antenna because ofnatural impedances that exist between the two.Nevertheless, the objective is to achieve the lowestSWR possible. In other words, we want only thecharacteristic impedance of the antenna remaining.
Incident Waves
Various factors in the antenna circuit affect theradiation of RF energy. When we energize or feed anantenna with an alternating current (ac) signal, waves ofenergy are created along the length of the antenna.These waves, which travel from a transmitter to the endof the antenna, are the incident waves.
Let’s look at figure 2-17. If we feed an ac signal atpoint A, energy waves will travel along the antennauntil they reach the end (point B). Since the B end isfree, an open circuit exists and the waves cannot travelfarther. This is the point of high impedance. Theenergy waves bounce back (reflect) from this point ofhigh impedance and travel toward the feed point, wherethey are again reflected.
Reflected Waves
We call the energy reflected back to the feed pointthe reflected wave. The resistance of the wiregradually decreases the energy of the waves in thisback-and-forth motion (oscillation). However, eachtime the waves reach the feed point (point A of figure2-17), they are reinforced by enough power to replace
Figure 2-17.—Incident and reflected waves on an antenna.
the lost energy. This results in continuous oscillationsof energy along the wire and a high voltage at point A onthe end of the wire. These oscillations are applied to theantenna at a rate equal to the frequency of the RFvoltage.
In a perfect antenna system, all the energy suppliedto the antenna would be radiated into space. In animperfect system, which we use, some portion of theenergy is reflected back to the source with a resultantdecrease in radiated energy. The more energy reflectedback, the more inefficient the antenna. The condition ofmost antennas can be determined by measuring thepower being supplied to the antenna (forward power)and the power being reflected back to the source(reflected power). These two measurements determinethe voltage standing wave ratio (VSWR), whichindicates antenna performance.
If an antenna is resonant to the frequency suppliedby the transmitter, the reflected waves and the incidentwaves are in phase along the length of the antenna andtend to reinforce each other. It is at this point thatradiation is maximum, and the SWR is best. When theantenna is not resonant at the frequency supplied by thetransmitter, the incident and reflected waves are out ofphase along the length of the antenna and tend to cancelout each other. These cancellations are called powerlosses and occur when the SWR is poor, such as 6:1 or5:1.
Most transmitters have a long productive life andrequire only periodic adjustment and routinemaintenance to provide maximum operating efficiencyand reliable communications. Experience has shownthat many of the problems associated with unreliableradio communication and transmitter failures can beattributed to high antenna VSWR.
Dummy Loads
Under radio silence conditions, placing a carrier onthe air during transmitter tuning would give an enemythe opportunity to take direction-finding bearings anddetermine the location of the ship. Even during normalperiods of operation, transmitters should be tuned bymethods that do not require radiation from the antenna.This precaution minimizes interference with otherstations using the circuit.
A dummy load (also called dummy antenna) can beused to tune a transmitter without causing unwantedradiation. Dummy loads have resistors that dissipatethe RF energy in the form of heat and prevent radiationby the transmitter during the tuning operation. The
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dummy load, instead of the antenna, is conected to theoutput of the transmitter, and the normal transmittertuning procedure is followed.
Most Navy transmitters have a built-in dummyload. This permits you to switch between the dummyload or the actual antenna, using a switch. Fortransmitters that do not have such a switch, thetransmission line at the transmitter is disconnected andconnected to the dummy load (figure 2-18). Whentransmitter tuning is complete, the dummy load isdisconnected and the antenna transmission line is againconnected to the transmitter.
ELECTROMAGNETIC WAVELENGTH
Electromagnetic waves travel through free space at186,000 miles per second. But, because of resistance,the travel rate of these waves along a wire is slightlyslower. An antenna must be an appropriate length sothat a wave will travel from one end to the other andreturn to complete one cycle of the RF voltage. Awavelength is the distance traveled by a radio wave inone cycle. This means that wavelength will vary withfrequency.
If we increase the frequency, the time required tocomplete one cycle of alternating current (at) isnaturally less; therefore, the wavelength is less. If wedecrease the frequency, the time required to completeone cycle of ac is longer; therefore, the wavelength islonger. Another word used to represent wavelength isLAMBDA (designated by the symbol i).
The term “wavelength” also refers to the length ofan antenna. Antennas are often referred to as half wave,quarter wave, or full wave. These terms describe the
Figure 2-18.—DA-91/U dummy load.
relative length of an antenna, whether that length iselectrical or physical.
Earlier, we said that when tuning an antenna, we areelectrically lengthening or shortening the antenna toachieve resonance at that frequency. We are actuallychanging the wavelength of the antenna. The electricallength of an antenna may not be the same as its physicallength.
You know that RF energy travels through space atthe speed of light. However, because of resistance, RFenergy on an antenna travels at slightly less than thespeed of light. Because of this difference in velocity, thephysical length no longer corresponds to the electricallength of an antenna. Therefore, an antenna may be ahalf-wave antenna electrically, but it is physicallysomewhat shorter. For information on how to computewavelengths for different frequencies, consult NEETS,Module 12, Modulation Principles.
BASIC ANTENNAS
Many types and variations of antenna design areused in the fleet to achieve a particular directiveradiation pattern or a certain vertical radiation angle.However, all antennas are derived from two basic types:the half wave and the quarter wave.
HALF-WAVE ANTENNA
An antenna that is one-half wavelength long is theshortest antenna that can be used to radiate radio signalsinto free space. The most widely used antenna is thehalf-wave antenna, commonly called a dipole, or hertz,antenna. This antenna consists of two lengths of wirerod, or tubing, each one-fourth wavelength long at acertain frequency.
Many complex antennas are constructed from thisbasic atenna design. This type of antenna will notfunction efficiently unless its length is one-halfwavelength of the frequency radiated or received.
Figure 2-19 shows a theoretical half-wave antennawith a center feed point. Both sections of the antenna
Figure 2-19.—Half-wave antenna with center feed point.
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are ~/4 (one-fourth wavelength) at the operatingfrequency. Together, of course, the sections make theeffective length of the antenna L/2 (one-halfwavelength) at the operating frequency.
One feature of the dipole antenna is that it does notneed to be connected to the ground like other antennas.Antennas shorter than a half wavelength must use theground to achieve half-wave characteristics. The half-wave antenna is already long enough to radiate thesignal properly.
Because of sophisticated antenna systems andtuning processes, half-wave antennas can beelectrically achieved aboard ship. Thereforewavelength is becoming less and less the criteria fordetermining the types of antennas to be used on ships.Dipole antennas can be mounted horizontally orvertically, depending upon the desired polarization, andcan be fed at the center or at the ends. Because it isungrounded, the dipole antenna can be installed aboveenergy-absorbing structures.
QUARTER-WAVE ANTENNA
A quarter-wave antenna is a grounded antenna thatis one-fourth wavelength of the transmitted or receivedfrequency. You will hear the quarter-wave antennareferred to as a “Marconi antenna.” The quarter-waveantenna is also omnidirectional.
As we mentioned earlier, a half-wave antenna is theshortest practical length that can be effectively used toradiate radio signals into free space. The naturalquestion, then is, “How do we use a quarter-wavelengthantenna if a half-wavelength is the shortest length thatcan be used?” The answer is simple.
Figure 2-20.—Direct and image signal of a quarter-waveantenna.
Figure 2-21.—Current distribution in a real antenna and itsimage.
Two components make up the total radiation froman antenna. One component is that part of the radiatedsignal which leaves the antenna directly. The other is aground reflection that appears to come from anunderground image of the real antenna (figure 2-20).This image is sometimes called the mirror image and isconsidered to be as far below the ground as the realantenna is above it.
Figure 2-21 shows basic current distribution in areal and image antenna. There are certain directions inwhich the direct wave from the real antenna and thereflected wave from the image are exactly equal inamplitude but opposite in phase. Conversely, there areother directions in which the direct and reflected wavesare equal in amplitude and in phase. Therefore,depending on the direction and location of the point atwhich the field strength is measured, the actual fieldstrength may be (1) twice the field strength from the realantenna alone, (2) zero field strength, or (3) someintermediate value between maximum and minimum.It is this “real” and “image” radiated field that forms thebasis for using quarter-wavelength antennas.
This reflected-energy principle is very useful in thelower frequency ranges, although ground reflectionsoccur in the high-frequency range as well.
The antenna does not always need to be placed atthe Earth’s surface to produce an image. Anothermethod of achieving reflected images is through the useof ground planes. This means that a large reflectingmetallic surface is used as a substitute for the ground orEarth. This method is frequently used in the VHF/UHF
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Figure 2-22.—AS-390/SRC UHF antenna with counterpoise,
Figure 2-24.—Wire rope fan antenna.
or ground plane.
frequency ranges. Figure 2-22 shows a commonly usedUHF antenna (AS-390/SRC), which uses this principle.The ground plane is sometimes referred to as a“counterpoise,” as shown in the figure. Together, the rope fans, whips, cages, dipoles, probes, trussedcounterpoise and the radials form the reflecting surface, monopoles, and bow stubs. The selection and use ofwhich provides the reflected image. different types is often governed by the limited space
available.
TYPES OF SHIPBOARD ANTENNAS WIRE ROPE ANTENNASFigure 2-23 shows various shipboard antennas and
their placements. The complex structures of modern Wire rope antennas are installed aboard ship forships and their operational requirements require the use medium- and high-frequency (300 kHz to 30 MHz)of many types of antenna. These types include wire coverage. A wire rope antenna (figure 2-24) consists of
Figure 2-23.—Shipboard antenna systems.
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one or more lengths of flexible wire rigged from two ormore points on the ship’s supurstructure. A wire ropeantenna is strung either vertically or horizontally from ayardarm or mast to outriggers, another mast, or to thesuperstructure. If used for transmitting, the wireantenna is tuned electrically to the desired frequency.
Receiving wire antennas are normally installedforward on the ship, rising nearly vertically from thepilothouse top to brackets on the mast or yardarm.Receiving antennas are located as far as possible fromthe transmitting antennas so that a minimum of energyis picked up from local transmitters.
Because of the characteristics of the frequencyrange in which wire antennas are used, the ship’ssuperstructure and other nearby structures become anelectronically integral part of the antenna. As a result,wire rope antennas are usually designed or adaptedspecifically for a particular ship.
WHIP ANTENNAS
Whip antennas are used for medium- and high-frequency transmitting and receiving systems. For low-frequency systems, whip antennas are used only forreceiving. Essentially self-supporting, whip antennasmay be deck-mounted or mounted on brackets on thestacks or superstructure. The self-supporting feature ofthe whip makes it particularly useful where space islimited and in locations not suitable for other types ofantennas. Whip antennas can be tilted, a design featurethat makes them suited for use along the edges ofaircraft carrier flight decks. Aboard submarines, theycan be retracted into the sail structure.
Whip antennas commonly used aboard ship are 25,28, or 35 feet long and consist of several sections. The35-foot whip is most commonly used. If these antennasare mounted less than 25 feet apart, they are usuallyconnected with a crossbar with the feed point at itscenter. The twin whip antenna (figure 2-25) is notbroadband and is generally equipped with a base tuningunit.
VHF AND UHF ANTENNAS
The physical size of VHF and UHF antennas isrelatively small because of the short wavelengths atthese frequencies. Aboard ship, these antennas areinstalled as high and as much in the clear as possible.
Figure 2-25.—Twin whip antenna with crowbar.
Since VHF and UHF antennas are line-of-sightsystems, they require a clear area at an optimum heighton the ship structure or mast. Unfortunately, this area isalso needed for various radars and UHF direction-finding and navigational aid systems.
VHF and UHF antennas are usually installed onstub masts above the foremast and below the UHFdirection finder. UHF antennas are often located on theoutboard ends of the yardarms and on other structuresthat offer a clear area.
For best results in the VHF and UHF ranges, bothtransmitting and receiving antennas must have the samepolarization. Vertically polarized antennas are used forall ship-to-ship, ship-to-shore, and ground-to-airVHF/UHF communications. Usually, either a verticalhalf-wave dipole or a vertical quarter-wave antennawith ground plane is used. An example of a UHF half-wave (dipole) antenna is the AT-150/SRC, shown in
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Figure 2-26.—AT-150/SRC UHF antenna.
Figure 2-27.—OE-82C/WSC-1(V) antenna group.
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Figure 2-28.—AS-2815/SSR-1 antenna physical configuration.
Figure 2-26. This antenna is normally mountedhorizontally.
BROADBAND ANTENNAS
Broadband antennas for HF and UHF bands havebeen developed for use with antenna multicouplers.Therefore, several circuits may be operated with asingle atenna. Broadband antennas must be able totransmit or receive over a wide frequency band.
HF broadband antennas include the 35-foot twinand trussed whips, half-cone, cage, and a variety of fan-
designed antennas. The AT-150/SRC UHF antenna infigure 2-26 is an example of a broadband antenna.
SATCOMM ANTENNAS
The antennas shown in figures 2-27 and 2-28 areused for satellite communications. The 0E-82C/WSC-1(V) antenna (figure 2-27) is used with the AN/WSC-3transceiver and designed primarily for shipboardinstallation. Depending upon requirements, one or twoantennas may be installed to provide a view of thesatellite at all times. The antenna is attached to apedestal. This permits the antenna to rotate so that it isalways in view of the satellite. The frequency band forreceiving is 248 to 272 MHz and for transmitting is 292to 312 MHz.
The AN/SRR-1 receiver system consists of up tofour AS-2815/SSR-1 antennas (figure 2-28) with anamplifier-converter AM-6534/SSR-1 for each antenna.The antennas are used to receive satellite fleetbroadcasts at frequencies of 240 to 315 MHz. Theantenna and converters are mounted above deck so thatat least one antenna is always in view of the satellite.
The newer satellite systems use the SHF band. Oneof the major advantages of these systems is that they usea very small parabolic antenna measuring only 12inches in diameter.
A satellite antenna must be pointed at the satellite tocommunicate. We must first determine the azimuth(AZ) and elevation (EL) angles from a fixed location.Figure 2-29 illustrates how these angles are derived,
Figure 2-29.—Equatorial Satellite Antenna Pointing Guide.
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using a pointing guide called the Equatorial SatelliteAntenna Pointing Guide. This guide is normallyavailable through the Navy Supply System.
The antenna pointing guide is a clear plasticoverlay, which slides across a stationary map. Itindicates AZ and EL angles in degrees to the satellite.The values obtained are useful to the operator in settingup the antenna control unit of a satellite system.
To use the guide, follow these procedures:
1. Center the overlay directly over the desiredsatellite position on the stationary map.
2. Mark the latitude and longitude of the ship onthe plastic antenna pointing guide with a greasepencil.
3. Determine the approximate azimuth angle fromthe ship to the satellite.
4. Locate the closest dotted line radiating outwardfrom the center of the graph on the overlay inrelation to the grease dot representing the ship’slocation. This dotted line represents degrees ofazimuth as printed on the end of the line. Someapproximation will be required for shippositions not falling on the dotted line.
5. Determine the degrees of elevation by locatingthe solid concentric line closest to the ship’smarked position. Again, approximation will berequired for positions not falling directly on thesolid elevation line. Degrees of elevation aremarked on each concentric line.
Example: Assume that your ship is located at30° north and 70° west. You want to accessFLTSAT 8 at 23° west. When we apply theprocedures above, we can determine an azimuthvalue of 115° and an elevation angle of 30°.
RHOMBIC ANTENNA
The rhombic antenna, usually used at receiver sites,is a unidirectional antenna. This antenna consists offour long wires, positioned in a diamond shape.Horizontal rhombic antennas are the most commonlyused antennas for point-to-point HF navalcommunications. The main disadvantage of thisantenna is that it requires a relatively large area.
MULTIWIRE RHOMBIC
A rhombic antenna improves in performance if eachleg is made up of more than one wire. An improved
antenna, known as a curtain rhombic, uses three wiresspaced 5 to 7 feet apart for each leg and connected to acommon point (figure 2-30).
SLEEVE ANTENNA
The sleeve antenna is used primarily as a receivingantenna. It is a broadband, vertically polarized,omnidirectional antenna. Its primary uses are inbroadcast, ship-to-shore, and ground-to-aircommunications. Although originally developed forshore stations, there is a modified version for shipboarduse. Figure 2-31 shows a sleeve antenna for shorestations.
Sleeve antennas are especially helpful in reducingthe total number of conventional narrowband antennasthat otherwise would be required to meet therequirements of shore stations. With the use ofmulticouplers, one sleeve antenna can serve severalreceivers operating over a wide range of frequencies.This feature also makes the sleeve antenna ideal forsmall antenna sites.
CONICAL MONOPOLE ANTENNA
The conical monopole antenna (figure 2-32) is usedin HF communications. It is a broadband, verticallypolarized, compact omnidirectional antenna. Thisantenna is adaptable to ship-to-shore, broadcast, andground-to-air communications. It is used both ashoreand aboard ship.
When operating at frequencies near the lower limitof the HF band, the conical radiates in much the samemanner as a regular vertical antenna. At the higherfrequencies, the lower cone section radiates, and the top
section pushes the signal out at a low angle as a skywave. This low angle of radiation causes the sky waveto return to the Earth at great distances from the antenna.
Figure 2-30.—Three-wire rhombic antenna.
2-24
Figure 2-31.—Sleeve antenna (shore stations).
Therefore, this antenna is well suited for long-distancecommunications in the HF band.
INVERTED CONE ANTENNA
The inverted cone antenna (figure 2-33) isvertically polarized, omnidirectional, and verybroadbanded. It is used for HF communications in ship-to-shore, broadcast, and ground-to-air applications.The radial ground plane that forms the ground systemfor inverted cones is typical of the requirement forvertically polarized, ground-mounted antennas. Theradial wires are one-quarter-wavelength long at thelowest designed frequency.
Figure 2-32.—Conical monopole antenna.
LOG-PERIODIC ANTENNA
The log-periodic (LP) antenna operates over anextremely wide frequency range in the HF and VHF
Figure 2-33.—Inverted cone antenna.
2-25
mechanisms. This antenna is particularly useful whereantenna area is limited. A rotatable LP antenna, knownas an RLP antenna (figure 2-35), possesses essentiallythe same characteristics as the fixed LP antenna but hasa different physical form. The RLP antenna iscommonly used in ship-shore-ship and in point-to-pointcommunications.
EMERGENCY ANTENNAS
Damage to an antenna from heavy seas, violentwinds, or enemy action can cause serious disruption ofcommunications. Sections of a whip antenna can becarried away, insulators can be damaged, or a wireantenna can snap loose from its moorings or break. Ifloss or damage should happen when all availableequipment is needed, you may have to rig, or assist in
Figure 2-34.—Log-periodic antenna. rigging, an emergency antenna to temporarily restorecommunications until the regular antenna can berepaired.
bands. Figure 2-34 shows a typical LP antenna The simplest emergency antenna consists of adesigned for extremely broadbanded, VHF length of wire rope to which a high-voltage insulator iscommunications. The LP antenna can be mounted on attached to one end and a heavy alligator clip, or lug, issteel towers or utility poles that incorporate rotating soldered to the other. The end with the insulator is
Figure 2-35.—Rotatable log-periodic antenna.
2-26
Figure 2-36.—Antenna multicoupler interconnection diagram.
hoisted to the nearest structure and secured. The endwith the alligator clip (or lug) is attached to theequipment transmission line. To radiate effectively, theantenna must be sufficiently clear of all groundedobjects.
ANTENNA DISTRIBUTIONSYSTEMS
In figure 2-36, we see a distribution system with oneantenna that can be connected (patched) to one ofseveral receivers or transmitters by way of amulticoupler. In this system, you can patch the antennato only one receiver or transmitter at a time. However,some distribution systems are more complex, such asthe one shown in figure 2-37. In this system, you canpatch four antennas to four receivers, or you can patchone antenna to more than one receiver via themulticoupler. In either system, we need a way toconnect the antenna to the receiver or transmitter thatwe want to use. Figure 2-37.—Complex distribution system.
2-27
Figure 2-38.—AN/SRA-12 antenna filter patch panel with receiver antenna patch panel.
Figure 2-38 shows a receiver antenna filter patchpanel, AN/SRA-12, with a receiver patch panel. TheAN/SRA-12 provides seven radio-frequency channelsin the 14-kHz to 32-MHz range. Any or all of thesechannels can be used independently of any otherchannel, or they can operate simultaneously.
On the receiver patch panel, a receiver is hardwiredto each jack. With the use of patchcords, you canconnect a receiver, tuned to a particular frequency, to theantenna by connecting the receiver to the proper jack onthe AN/SRA-12. Figure 2-38 shows how the filterassembly is used in combination with other units to passan RF signal from an antenna to one or more receivers.
NOTE
When patching, YOU MUST ALWAYSINSERT THE END OF THE ANTENNAPATCH CORD TO THE RECEIVERJACK FIRST. THEN, YOU INSERT THEOTHER END OF THE PATCH CORDINTO THE LOWEST USABLE AN/SRA-12 JACK. TO UNPATCH, ALWAYSREMOVE THE PATCH CORD FROMTHE RECEIVER JACK, THEN THEOTHER END FROM THE FREQUENCYFILTER JACK. An easy way to rememberthis is always work the patching from the topdown.
2-28
Transmitting antenna distribution systems performthe same functions as receiving distribution systems.Figure 2-39 shows a transmitter patch panel. These
Figure 2-39.—Transmitter antenna patch panel.
transmitter patch panels are interlocked with thetransmitter so that no open jack connection can beenergized and no energized patch cord can be removed.This provides safety for both personnel and equipment.
ANTENNA POSITIONING
Raise and lower antennas - raising and loweringphysically of antennas is associated with flight,refueling or PMS operations. Extreme care should betaken that all moving parts are in correct operatingconditions and the Officer of the Deck orCommunications Watch Officers know prior to thephysical movement of the antennas.
USE DIRECTIONAL ANTENNAS
Reception is defined as: when an electromagneticwave passes through a receiver antenna and induces avoltage in that antenna. Further detailed information onantennas, antenna use, wave propagation and wavegeneration can be found in NEETS MODULES 9, 10,and 17.
Rotate For Optimum Reception
This is accomplished by both physical andmechanical means of moving the antenna(s) to properlyalign and tune the antenna.
Align For Optimum Reception
Using the correct antenna location (by rotation) andthe correct equipment for the system, you will bring theantenna into alignment and be ready for the final step,which is tuning.
Tune For Optimum Reception
There are two objectives of antenna tuning: (1) totune out the various impedances and (2) to match thelength of the antenna to the frequency radiated at itscharacteristic impedance.
Impedance: everything exhibits someimpedance, Even a straight piece of copper wire3 inches long will offer some resistance tocurrent flow, however small. The characteristicimpedance of this same piece of copper wire is itsoverall resistance to a signal.
The transmission line between an antenna and atransmitter has a certain amount of characteristicimpedance. The antenna also has a certain amount of
characteristic impedance. This basic mismatch inimpedance between the transmitter and the antennamakes antenna tuning necessary. Naturally, astransmitters, transmission lines, and antennas becomemore complex, antenna tuning becomes more critical.
Antenna length adjustment: When we tune anantenna, we electrically (not physically)lengthen and shorten it. The radiation resistancevaries as we vary the frequency of the transmitterand tune the antenna. The radiation resistance isnever perfectly proportional to antenna lengthbecome of the effects of the antenna height abovethe ground and its location to nearby objects.
You will find that the better the ability of thereceiver to reject unwanted signals, the better itsselectivity, The degree of selection is determinedly thesharpness of resonance to which the frequency-determining circuits have been engineered and tuned.You usually measure selectivity by taking a series ofsensitivity readings. As you take the readings, you stepthe input signal along a band of frequencies above andbelow the circuit resonance of the receiver; forexample, 100 kilohertz below to 100 kilohertz above thetuned frequency. As you approach the tuned frequency,the input level required to maintain a given output levelwill fall. As you pass the tuned frequency, the requiredinput level will rise. Input voltage levels are thencompared with frequency. They can be plotted onpaper, or you may can view them on an oscilloscope.They appear in the form of a response curve. Thesteepness of the response curve at the tuned frequencyindicates the selectivity of the receiver, thus allowingfor the optimum reception.
RF SAFETY PRECAUTIONS
Although electromagnetic radiation fromtransmission lines and antennas is usually ofinsufficient strength to electrocute personnel, it can leadto other accidents and compound injuries. Voltages maybe inducted in ungrounded metal objects, such as wireguys, wire cable (hawser), hand rails, or ladders, If youshould come in contact with these objects, you couldreceive a shock or RF burn. This shock can cause you tojump or fall into nearby mechanical equipment or, whenworking aloft, to fall from an elevated work area. Takecare to ensure that all transmission lines or antennas aredeenergized before working near or on them.
Guys, cables, rails and ladders should be checkedfor RF shock dangers. Working aloft “chits” and safetyharnesses should be used for your safety. Signing a
2-29
2-30
“working aloft chit” signifies that all equipment is in anonradiating status (the equipment is not moving). Theperson who signs the chit should ensure that no RFdanger exists in areas where personnel are working.
Nearby ships or parked aircraft are another sourceof RF energy that must be considered when checkingwork areas for safety. Combustible materials can beignited and cause severe fires from arcs or heatgenerated by RF energy. RF radiation can detonateordnance devices by inducing currents in the internalwiring of the device or in the external test equipment, orleads connected to the device.
You should always obey RF radiation warningsigns and keep a safe distance from radiating antennas.The six types of warning signs for RF radiation hazardare shown in figure 2-40.
RF BURNS
Close or direct contact with RF transmission linesor antennas may result in RF burns. These are usuallydeep, penetrating, third-degree burns. To heal properly,these burns must heal from the inside to the skin surface.To prevent infection, you must give proper medicalattention to all RF burns, including the small “pinhole”burns. Petrolatum gauze can be used to cover burnstemporarily before the injured person reports to medicalfacilities for further treatment.
DIELECTRIC HEATING
Dielectric heating is the heating of an insulatingmaterial by placing it in a high frequency electric field.The heat results from internal losses during the rapidreversal of polarization of molecules in the dielectricmaterial.
In the case of a person in an RF field, the body actsas a dielectric, If the power in the RF field exceeds 10milliwatts per centimeter, a person in that field will havenoticeable rise in body temperature. The eyes arehighly susceptible to dielectric heating. For this reason,you should not look directly into devices radiating RFenergy. The vital organs of the body are also susceptibleto dielectric heating. For your own safety, you must notstand directly in the path of RF radiating devices.
PRECAUTIONS WHEN WORKING ALOFT
Prior to going aloft, you must follow all NAVOSHand local requirements such as wearing a harness and ahard hat. You must have a safety observer and meet allother requirements.
When radio or radar antennas are energized bytransmitters, you must not go aloft unless advance testsshow that little or no danger exists. A casualty can occurfrom even a small spark drawn from a charged piece ofmetal or rigging. Although the spark itself may beharmless, the “surprise” may cause you to let go of theantenna involuntarily, and you may fall. There is also ashock hazard if nearby antennas are energized.
Rotating antennas also may cause you to fall whenyour are working aloft. Motor safety switchescontrolling the motion of rotating antennas must betagged and locked opened before you go aloft near suchantennas.
When working near a stack, you should draw andwear the recommended oxygen breathing apparatus.Among other toxic substances, stack gas containscarbon monoxide. Carbon monoxide is too unstable tobuild up to a high concentration in the open, butprolonged exposure to even small quantities isdangerous.
SUMMARY
Naval communications using satellite and variousantennas types must always be ready to shift frompeacetime to wartime requirements. To this end, thediversity of fleet communication operations has giventhe Navy an expanded capability to meet ever-increasing command, control, and supportrequirements by use of satellites and assorted antennas.
Additionally, this variety of communicationstechnology has increased the requirements for greaterproficiency from all operating personnel. As aRadioman, you will be tasked with higher levels ofperformance in an increasingly technical Navy.
2-31
APPENDIX I
GLOSSARY
A
ANTENNA— A device used to radiate or receive radiowaves.
ANTENNA COUPLER— A device used for impedancematching (tuning) between an antenna and a transmitteror receiver.
ANTENNA RECIPROCITY— The ability of an antennato both transmit and receive electromagnetic energy.
ANTENNA TUNING— The process where an antenna iselectrically “matched” to the output frequency andimpedance of the transmitter.
ATTENUATION— A deliberate reduction or anunintended loss in RF signal strength.
B
BANDWIDTH— Any section of the frequency spectrumoccupied by specific signals.
BIDIRECTIONAL ANTENNA— An antenna thatradiates in or receives most of its energy from only twodirections.
BLACK— Cipher text or encrypted text or information
C
CARRIER— The unmodulated signal originally producedin the oscillator section of a transmitter.
CARRIER FREQUENCY— The final RF output withoutmodulation. The assigned transmitter frequency.
CHANNEL— A carrier frequency assignment, usually witha fixed bandwidth.
COMPLEX WAVE— A transmitted radio signalcomposed of different frequencies.
COUNTERPOISE— The ground plane, or reflectivesurface, comprising an antenna’s reflected image at agiven wavelength.
CRITICAL FREQUENCY— The highest transmittedfrequency that can be propagated directly upward andstill be bent, or “refracted,” back to Earth.
CYCLE— Two complete alternations of alternating current,or one complete revolution in any period of time, equalto 360°.
D
DAMA (DEMAND ASSIGNED MULTIPLE ACCESSSUBSYSTEM)— Subsystem that multiplexes severalsubsystems on one satellite channel.
DIFFRACTION— The bending of radio waves around theedges of a solid objector dense mass.
DIRECTIONAL ANTENNA— An antenna that radiatesor receives radio waves more effectively in somedirections than in others.
DIRECTIVITY— The sharpness or narrowness of anantenna’s radiation pattern in a given plan.
DIRECT WAVE— A radio signal that travels in a directline-of-sight path from the transmitting antenna to thereceiving antenna.
DUMMY LOAD— A nonradiating device used at the endof a transmission line in place of an antenna for tuning atransmitter, The dummy load converts transmittedenergy into heat so that no energy is radiated outward orreflected back.
E
EHF (EXTREMELY HIGH FREQUENCY)— The bandof frequencies from 30 GHz to 300 GHz.
ELECTRIC FIELD— A field produced as a result of avoltage charge on an antenna.
ELECTROMAGNETIC ENERGY— An RF sourcecomposed of both an electric and a magnetic field.
ELECTROMAGNETIC WAVES— Energy produced atthe output of a transmitter; also called radio waves.
F
FADING— Variation, usually gradual, in the field strengthof a radio signal that is caused by changes in thetransmission path or medium.
AI-1
FEED POINT— The point on an antenna at which the RFcable that carries the signal from the transmitter isconnected.
FOT (FREQUENCY OF OPTIMUM TRANS-MISSION)— The most reliable frequency forpropagation at a specific time.
FREQUENCY— The number of complete cycles per unitof time.
FREQUENCY DIVERSITY— The method in which theinformation signal is transmitted and received on twoseparate radio frequencies simultaneously to takeadvantage of the fact that fading does not occursimultaneously on different frequencies.
FSK (FREQUENCY-SHIFT KEYING)— The process ofshifting the incident carrier above and below the carrierfrequency to correspond to the marks and spaces of ateleprinter signal.
G
GAIN— An increase in signal strength.
GIGAHERTZ (GHz)— A unit of frequency equal to 1000megahertz.
GROUND— A term used to denote a common electricalpoint of zero potential.
GROUND-PLANE ANTENNA— A type of antenna thatuses aground plane (a metallic surface) as a simulatedground to produce low-angle radiation.
H
HALF-WAVE DIPOLE ANTENNA— A common typeof half-wave antenna made from a straight piece of wirecut in half. Each half operates at a quarter of thewavelength It is normally omnidirectional with nogain.
HERTZ (Hz)— A unit of frequency equal to one cycle persecond.
HERTZ ANTENNA— An ungrounded half-wave antennathat is installed some distance above ground andpositioned either vertically or horizontally.
HF (HIGH FREQUENCY)— The band of frequencies from3MHz to 30MHz.
I
IMPEDANCE— The total opposition to the flow ofalternating current.
INCIDENT WAVE— The RF energy that travels from thetransmitter to the antenna for radiation.
INDUCTION FIELD— The electromagnetic fieldproduced around an antenna when current and voltageare present on the antenna.
K
KILOHERTZ (kHz)— A unit of frequency equal to 1000hertz.
L
LEASAT— Leased satellite.
LF (LOW FREQUENCY)— The band of frequencies from30kHz to 300kHz.
LUF (LOWEST USABLE FREQUENCY)— The lowestfrequency that can be used at a specific time forionospheric propagation of radio waves between twospecified points.
M
MAGNETIC FIELD— One of the fields produced whencurrent flows through a conductor or an antenna.
MARCONI ANTENNA— A quarter-wave antenna that isoperated with one end grounded; it is positionedperpendicular to the Earth.
MEGAHERTZ (MHz)— A unit of frequency equal tol,000,000 hertz.
MF (MEDIUM FREQUENCY)— The band of frequenciesfrom 300kHz to 3MHz.
MIRROR IMAGE— The part of the radiated signal of aquarter-wave antenna (Marconi antenna) appearing tocome from an underground image of the real antenna.This image is also called ground reflection.
MODULATED WAVE— The wave that results after theinformation from the modulating signal is impressedonto the carrier signal. The wave that is transmitted
MODULATION— The process of adding, orsuperimposing, information on an RF carrier wave.
MUF (MAXIMUM USABLE FREQUENCY)— Thehighest operating frequency that can be used at a specifictime for successful radio communications between twopoints.
AI-2
O
OMNIDIRECTlONAL ANTENNA— An antenna thatradiates or receives equally well in all directions, exceptdirectly off the ends.
OSCILLATOR— An electrical circuit that generatesalternating current at a particular frequency.
P
PARABOLIC ANTENNA— An antenna that radiates itssignal back into a large reflecting surface (called thedish) for radiation.
PERIOD (of a wave)— The time required to complete onecycle of a waveform.
POLARIZATION (of antennas)— The plane (horizontalor vertical) of the electric field as radiated from atransmitting antenna.
R
RADHAZ (RADIATION HAZARD)— Electromagneticradiation hazard generated from electronic equipment.
RADIATION FIELD— The electromagnetic field thatradiates from an antenna and travels through space.
RADIATION RESISTANCE— The resistance that, ifinserted in place of an antenna, would consume the sameamount of power that is radiated by the antenna.
RECIPROCITY— See antenna reciprocity.
RED— Plain text or unencrypted information
REFLECTED WAVE— An electromagnetic wave thattravels back toward the transmitter from the antennabecause of a mismatch in impedance between the two.
REFLECTION— Occurs when a radio wave strikes theEarth’s surface at some distance from the transmittingantenna and is returned upward toward the atmosphere.
RF (RADIO FREQUENCY)— A frequency in the rangewithin which radio waves can be transmitted.Frequencies used for radio communication fall between3kHz and 300GHz.
RF ENERGY— Radio frequency energy. Energyproduced at the output of a transmitter.
S
SATELLITE COMMUNICATION (SATCOM)— Atype of worldwide, reliable, high-capacity, secure, andcost-effective telecommunications system utilizingsatellites.
SHF (SUPER HIGH FREQUENCY)— The band offrequencies from 3 GHz to 30 GHz.
SIGNAL— Detectable transmitted energy that can be usedto carry information.
STANDING WAVES— The stationary waves that buildupalong an antenna during radiation.
SWITCHBOARD— Device that connects receiver outputsto numerous pieces of equipment.
SWR (STANDING-WAVE RATIO)— A term used toexpress the degree of resonance attained between theantenna and the transmission line when being tuned fortransmission.
T
TRANSMISSION LINE— A device designed to guideelectrical or electromagnetic energy from one point toanother.
U
UHF (ULTRA HIGH FREQUENCY)— The band offrequencies from 300 MHz to 3 GHz.
UNIDIRECTIONAL ANTENNA— An antenna thatradiates in only one direction.
V
VHF (VERY HIGH FREQUENCY)— The band offrequencies from 30 MHz to 300 MHz.
VLF (VERY LOW FREQUENCY)— The band offrequencies from 3 kHz to 30 kHz.
W
WAVEFORM— The shape of an electromagnetic wave.
WAVELENGTH— The distance traveled, in feet ormeters, by a radio wave in the time required for onecycle.
AI-3
APPENDIX II
GLOSSARY OF ACRONYMS AND ABBREVIATIONS
A
ASWIXS— Antisubmarine Warfare Information ExchangeSubsystem.
ASWOC— Antisubmarine Warfare Operations Center.
AZ— Azimuth.
C
CAT— Communications assistance team.
CONUS—— Continental United States.
CUDIXS— Common User Digital Information ExchangeSystem.
CW— Continuous wave (Morse code).
D
DAMA— Demand Assigned Multiple Access Subsystem.
dc— Direct current.
DSB— Double-side band.
DSCS— Defense Satellite Communications System.
E
EHF— Extremely high frequency.
EL— Elevation
EMCON— Emission control.
F
FDM— Frequency division multiplexing.
FDMA— Frequency division multiple access.
FDX— Full duplex.
FFN— Fleet flash net.
FLTCINC— Fleet Commander-in-Chief.
FLTSATCOM— FM satellite communications.
FOT— Frequency of optimum transmission.
FSB— Fleet satellite broadcast.
FSK— Frequency-shift keying.
G
GHz— Gigahertz.
H
HDX— Half duplex.
HERO— Hazardous electromagnetic radiation.
HF— High frequency.
HPA— High Power amplifier.
Hz— Hertz.
I
IF— Intermediate frequency.
K
kHz— Kilohertz.
L
LEASAT— Leased satellite.
LF— Low frequency.
LNA— Low noise amplifier.
LOS— Line of sight.
LP— Log-periodic antenna.
LPI— Low probability of intercept.
LSTDMs— Low speed time division multiplexer.
LUF— Lowest usable frequency.
M
MHz— Megahertz.
MF— Medium frequency.
AII-1
MPA— Medium power amplifier.
MUF— Maximum usable frequency.
N
NATO— North Atlantic Treaty Organization.
NAVCOMTELSTA— Naval Computer and Tele-communications station.
NAVMACS— Naval Modular Automated Com-munications System.
NCTAMS— Naval Computer and TelecommunicationsArea Master Station.
NCTS— Naval Computer and Telecommunicationsstations.
NECOS— Net control station.
O
ORESTES— Teleprinter subsystem.
OTAR— Over-the-air relay.
OTAT— Over-the-air transfer.
OTC— Officer in tatical command.
OTCIXS— Officer in Tactical Command InformationExchange Subsystem.
P
PRIS/S— Primary ship-shore.
PSK— Phase shift keying.
R
RADHAZ— Radiation hazard.
RF— Radio frequency.
RLP— Rotatable log-periodic antenna.
S
SAR— Search and air rescue.
SATCOM— Satellite communication.
SECVOX— Secure voice.
SHF— Super high frequency.
SSB— Single-sideband.
SSIXS— Submarine Satellite Information ExchangeSubsystem.
SWR— Standing-wave ratio.
T
TACINTEL— Tactical intelligence system.
TADIXS— Tactical Data Information ExchangeSubsystem.
TDM— Time division multiplexing.
TDMA— Time division multiple access.
U
UHF— Ultra high frequency.
V
VHF— Very high frequency.
VSWR— Voltage standing-wave ratio.
VLF— Very low frequency.
AII-2
APPENDIX Ill
REFERENCES USED TO DEVELOPTHIS TRAMAN
NOTE: The following references were current at the time thisTRAMAN was published, but you should be sure you have thecurrent editions.
Basic Operational Communications Doctrine (U), NWP 4(B)/NWP 6-01, Chief ofNaval Operations, Washington, D.C., September 1989.
Communication Instructions—General (U), ACP 121(F), Joint Chiefs of Staff,Washington, D.C., April 1983.
Communications Instructions—General, ACP 121 US SUPP-l(F), Joint Chiefs ofStaff, Washington, D.C., June 1981.
Communications Instructions—Teletypewriter (Teleprinter) Procedures, ACP126(C), Joint Chiefs of Staff, Washington, D.C., May 1989.
Communications Security Material System (CMS) Policy and Procedures Manual,CMS 1, Department of the Navy, Washington, D.C., March 1993.
Fleet Communications (U), NTP 4(C), Commander, Naval TelecommunicationsCommand, Washington, D.C., June 1988.
Naval Telecommunications Procedures, Recommended Frequency Bands andFrequency Guide, NTP 6 Supp-l(S), Commander, Naval Computer andTelecommunications Command, Washington, D.C., 1993.
Naval Telecommunications Procedures, Spectrum Management Manual, NTP6(C), Commander, Naval Telecommunications Command, Washington, D.C.,November 1988.
Naval Warfare Documentation Guide, NWJP 0 (Rev. P)/NWP 1-01, Chief ofNaval Operations, Washington, D.C., January 1990.
Navy Electricity and Electronics Training Series, Module 1, Introduction toMatter, Energy, and Direct Current, NAVEDTRA B72-01-00-92, NETPDTC,Pensacola, Fla., 1992.
Navy Electricity and Electronics Training Series, Module 2, Introduction toAlternating Current and Transformers, NAVEDTRA 172-02-00-91,NETPDTC, Pensacola, Fla., 1991.
AIII-1
Navy Electricity and Electronics Training Series, Module 8, Introduction toAmplifiers, NAVEDTRA 172-08-00-82, NETPDTC, Pensacola, Fla., 1982.
Navy Electricity and Electronics Training Series, Module 9, Introduction to Wave-Generation and Wave-Shaping Circuits, NAVEDTRA 172-09-00-83,NETPDTC, Pensacola, Fla., 1983.
Navy Electricity and Electronics Training Series, Module 10, Introduction to WavePropagation, Transmission Lines, and Antennas, NAVEDTRA 172-10-00-83,NETPDTC, Pensacola, Fla., 1983.
Navy Electricity and Electronics Training Series, Module 12, ModulationPrinciples, NAVEDTRA 172-12-00-83, NETPDTC, Pensacola, Fla., 1983.
Navy Electricity and Electronics Training Series, Module 17, Radio-FrequencyCommunications Principles, NAVEDTRA 172-17-00-84, NETPDTC,Pensacola, Fla., 1984.
Navy Occupational Safety and Health (NAVOSH) Program Manual for ForcesAfloat, Vols I and II, OPNAVINST 5100.19B, Chief of Naval Operations,Washington, D.C., April 1989.
Navy Super High Frequency Satellite Communications, NTP 2, Section 1 (C),Naval Computer and Telecommunications Command, Washington, D.C.,June 1992.
Navy UHF Satellite Communication System Description, IWCS-200-83-1,Commander, Naval Ocean Systems Center, San Diego, Calif., 1991.
Navy UHF Satellite Communication System—Shipboard, EE130-PL-OMI-010/W142-UHFSATCOM, Space and Naval Warfare Systems Command,Washington, D.C., August 1986.
Navy Ultra High Frequency Satellite Communications (U), NTP 2, Section 2 (E),Naval Computer and Telecommunications Command, Washington, D.C., July1992.
Operational Reports, NWP 10-1-10/NWP 1-03.1, Chief of Naval Operations,Washington, D.C., November 1987.
Secure Telephone Unit Third Generation (STU-III) COMSEC MaterialManagement Manual, CMS 6, Director, Communications Security MaterialSystem, Washington, D.C., October 1990.
Shipboard Antenna Systems, Volume 1, Communications Antenna Fundamentals,NAVSHIPS 0967-177-3010, Naval Ship Systems Command, Washington,D.C., September 1972.
Shipboard Antenna Systems, Volume 3, Antenna Couplers, CommunicationsAntenna Systems, NAVSHIPS 0967-177-3030, Naval Ship SystemsCommand, Washington, D. C., January 1973.
AIII-2
Shipboard Antenna Systems, Volume 5, Antenna Data Sheets, SPAWAR 0967-LP-177-3050, Space and Naval Warfare Systems Command, Washington, D.C.,May 1973.
Ships’ Maintenance and Material Management (3-M) Manual, OPNAVINST4790.4B, Chief of Naval Operations, Washington, D.C., August 1987.
Telecommunications Users Manual, NTP 3(I), Commander, NavalTelecommunications Command, Washington, D.C., January 1990.
AIII-3
INDEX
A
Antennas, 2-20
broadband, 2-23
conical monopole, 2-24
emergency, 2-26
inverted cone, 2-25
log-periodic, 2-25
multiwire rhombic, 2-24
quarter-wave, 2-19
rhombic, 2-24
SATCOM, 2-23
sleeve, 2-24
UHF, 2-21
whip, 2-21
wire rope, 2-20
VHF, 2-21
Antenna distribution system, 2-27
Antenna positioning, 2-29
align for optimum reception, 2-29
rotate for optimum reception, 2-29
tune for optimum reception, 2-29
use, 2-29
Antenna systems, 2-14
bidirectional, 2-15
characteristics, 2-15
directivity, 2-15
dummy load, 2-17
feed point, 2-15
Antenna systems—Continued
unidirectional, 2-15
voltage standing wave ratio (VSWR), 2-16
wave polarization, 2-15
AN/UCC-l, 1-2, 1-8
ASWIXS, 2-10, 2-12
AUTOCAT, 2-14
C
COMMSPOT reports, 1-14
Cryptographic equipment, 1-8
CUDIXS, 1-14, 2-13
D
DAMA, 2-7, 2-13
Distress communications, 1-14
emergency, 2-26
frequencies, 1-15
OTC, 1-15
SAR frequencies, 1-15
watches, 1-15
Double-side band, 1-8
Dummy load, 2-17
E
Electromagnetic wavelength, 2-18
full wave, 2-18
half wave, 2-18
quarter wave, 2-18
Fincident waves, 2-17 FDMA, 2-7omnidirectional, 2-15 Feed point, 2-15reciprocity, 2-15 center-fed, 2-15reflected waves, 2-17 end-fed, 2-15standing wave ratio (SWR), 2-15 mid-fed, 2-15
INDEX-1
FFN, 2-14
Fleet broadcast system, 2-9
Fleet broadcast system equipment, 2-9
AM-6534/SSR-l amplifier-converter, 2-9
AN/ARC-143 UHF transceiver, 2-9
AN/FSC-79 Fleet Broadcast terminal, 2-9
AN/SSR-l receiver, 2-9
AN/WSC-3 (UHF) transceiver, 2-9
AN/WSC-5 (UHF) transceiver, 2-9
Antisubmarine Warfare Information ExchangeSubsystem (ASWIXS), 2-10, 2-12
Fleet Satellite Broadcast (FSB), 2-11
MD-900/SSR-l combiner-demodulator, 2-9
TD-1063/SSR-1 demultiplexer, 2-9
Fleet Satellite Communications (FLTSATCOM), 2-11
Antisubmarine Warfare Information ExchangeSubsystem (ASWIXS), 2-12
circuit restoral/coordination, 2-14
Common User Digital Information ExchangeSystem (CUDIXS), 2-12
Control subsystem, 2-13
Demand Assigned Multiple Access (DAMA), 2-13
Fleet Flash Net (FFN), 2-14
Fleet Satellite Broadcast, (FSB), 2-11
LEASAT telemetry tracking and commandsubsystem, 2-13
Naval Modular Automated CommunicationsSystem (NAVMACS), 2-12
Officer in Tactical Command InformationExchange Subsystem (OTCIXS), 2-13
Secure voice, 2-12
special circuits, 2-14
Submarine Satellite Information ExchangeSubsystem (SSIXS), 2-12
Tactical Data Information Exchange Subsystem,(TADIXS), 2-12
Tactical Intelligence subsystem, 2-13
Teleprinter Subsystem (ORESTES), 2-13
FLTSATCOM, 2-11
Frequency-shift keying (FSK), 1-11
FSB, 2-11
Full-period terminations, 1-13
CUDIXS, 1-14
equipment tests, 1-14
NAVMACS, 1-14
termination requests, 1-13
termination types, 1-14
TACINTEL, 1-14
G
GPS, 1-13
H
Hazardous electromagnetic radiation (HERO), 1-12
High-frequency receive system, 1-3
antenna, 1-4
antenna patch panel, 1-4
AN/UCC-1, 1-4
AN/UCC-l receive telegraph terminal, 1-4
black dc patch panel, 1-4
cryptoequipment, 1-4
C-1004 transmit keying and receiver control, 1-4
C-1138 radio set control, 1-4
R-2368/UR receiver, 1-4
red dc patch panel, 1-4
reperforator, 1-4
SB-973/SRR receiver transfer switchboard, 1-4
SB-1203/UG black, 1-4
SB-1210/UGO, 1-4
speaker, 1-4
teleprinter, 1-4
High-frequency transmit systems, 1-3
AN/UCC-1, 1-3
AN/UCC-1 telegraph terminal, 1-3
AN/URT-23, 1-3
antenna, 1-3
INDEX-2
High-frequency transmit systems—Continued
black dc patch panel, 1-3
couplers, 1-3
cryptoequipment, 1-3
C-1004 transmit keying and receiver control, 1-3
C-1138 radio set control, 1-3
red dc patch panel, 1-3
SB-988/SRT, 1-3
SB-1210/UGQ, 1-3
teleprinter, 1-3
transmitter, 1-3
transmitter transfer switchboard, 1-3
HPA, 2-8
L
LNA, 2-8
Low-frequency systems, 1-2
antennas, 1-2
AN/FRT-72, 1-2
AN/UCC-1, 1-2
black dc patch panel, 1-3
converter comparator, 1-3
cryptoequipment, 1-3
receiver, R-2368/URR, 1-3
red dc patch panel, 1-3
printer, 1-3
reperforator, 1-3
SB-1203/UG dc patch panel, 1-3
SB-1210/UGQ dc patch panel, 1-3
SB-973/SRR, 1-3
LPI, 2-8
M
MARCONI antenna, 2-19
MIDDLEMAN, 2-14
MPA, 2-8
Multiplexing, 1-8, 2-13
frequency-division (FDM), 1-10
low speed time division multiplexer (LSTDMs),2-6
time-division multiplexer (TDM), 1-10
twinning, 1-10
N
Net control station, 1-12
NECOS, 1-12, 1-13
NAVMACS, 2-12
O
ORESTES, 2-13
OTAT/OTAR, 1-14
OTCIXS, 2-13
Over-the-air rekey, 1-14
Over-the-air transfer, 1-14
P
Patch panels, 1-3, 1-4, 1-6
Primary ship-shore circuits, 1-14
FSK, 1-11, 1-14
PSK, 1-14, 2-7
Q
Quality monitoring, 1-18
AN/SSQ-88 equipment, 1-17
AN/SSQ-88 quality monitoring set, 1-18
program, 1-18
system, 1-18
R
RF safety precautions, 2-29
burns, 2-30
dielectric heating, 2-31
equipment, 2-29
precautions, 2-31
INDEX-3
RF safety precautions—Continued
warning signs, 2-30
working aloft chits, 2-31
S
SATCAT, 2-14
SATCOM antennas, 2-1
AS-29151SSR-1, 2-2
DAMA, 2-6
frequency division multiple access (FDMA), 2-7
FLTSATCOM, 2-4
GAPFILLER, 2-4
LEASAT, 2-5
low speed time division multiplexer (LSTDMs),2-6
OE-83C/WSC-l(V) group, 2-1
phase shift keying (PSK), 2-7
PHASE IV, 2-6
pointing guide, 2-3
time division multiple access (TDMA), 2-7
types, 2-3
SATCOM system, 2-7
Fleet Broadcast System, 2-9
Fleet Satellite Communications, 2-11
high power amplifier (HPA), 2-8
low noise amplifier (LNA), 2-8
low probability of intercept (LPI), 2-8 medium
power amplifier (MPA), 2-8
Secure voice worldwide voice network, 1-13
net membership, 1-13
satellite system control, 1-13
system control, 1-13
Ship-shore circuits, 1-10
duplex, 1-10
full duplex (FDX), 1-11
half duplex (HDX), 1-11
methods, 1-10
Ship-shore circuits—Continued
semiduplex, 1-12
simplex, 1-11
Single-sideband, 1-8
Special circuits, 2-14
AUTOCAT, 2-14
MIDDLEMAN, 2-14
SATCAT, 2-14
SSIXS, 2-12
Status board, 1-15
Super-high frequency systems, 1-6
SWR, 2-16
T
TACINTEL, 1-14,2-13
TADIXS, 2-12
TDMA, 2-7
U
Ultra-high frequency systems, 1-5
Ultra-high frequency receive system, 1-6
antenna, 1-6
AM-3729 speaker amplifier, 1-6
AN/SRA-33 antenna coupler, 1-6
AN/WSC-3 receiver, 1-6
C-1138 radio set control (nonsecure), 1-6
handset 1-6
SB-973/SRR receiver transfer switchboard, 1-6
secure remote phone unit, 1-6
secure voice equipment, 1-6
secure voice matrix, 1-6
speaker, 1-6
Ultra-high frequency transmit system, 1-5
antenna, 1-5
AN/SRA-33 antenna coupler, 1-5
AN/WSC-3 transmitter, 1-5
C-1138 radio set control, 1-5
INDEX-4
Ultra-high frequency transmit system—Continued V
handset, nonsecure, 1-5
patch panel, 1-5
remote phone unit (RPU), 1-5
SB-988/SRT transmitter transfer switchboard, 1-5
secure remote phone unit, 1-5
secure voice equipment, 1-5
secure voice matrix, 1-5
Underway preparation, 1-1
predeployment check-off sheet, 1-2
preunderway check-off sheet, 1-2
Very-high frequency systems, 1-4
AM-3729 speaker amplifier, 1-4
C-1138 radio set control, 1-4
handset, 1-4
SB-973/SRR receiver transfer switchboard, 1-4
SB-988/SRT transmitter transfer switchboard,1-4
speaker, 1-4
transceiver (receiver/transmitter), 1-4
VSWR, 2-16
INDEX-5
RADIOMAN TRAINING SERIESMODULE 4 - COMMUNICATIONS HARDWARE
NAVEDTRA 12848
Prepared by the Naval Education and Training Professional Developmentand Technology Center (NETPDTC), Pensacola, Florida
Congratulations! By enrolling in this course, you have demonstrateda desire to improve yourself and the Navy. Remember, however, thisself-study course is only one part of the total Navy trainingprogram. Practical experience, schools, selected reading, and yourdesire to succeed are also necessary to successfully round out afully meaningful training program. You have taken an important stepin self-improvement. Keep up the good work.
HOW TO COMPLETE THIS COURSESUCCESSFULLY
ERRATA: If an errata comes with thiscourse, make all indicated changes orcorrections before you start anyassignment. Do not change or correctthe associated text or assignments inany other way.
TEXTBOOK ASSIGNMENT: The textpages that you are to study arelisted at the beginning of eachassignment. Study these pagescarefully before attempting to answerthe questions in the course. Payclose attention to tables andillustrations because they containinformation that will help youunderstand the text. Read thelearning objectives provided at thebeginning of each chapter or topic inthe text and/or preceding each set ofquestions in the course. Learningobjectives state what you should beable to do after studying thematerial. Answering the questionscorrectly helps you accomplish theobjectives.
SELECTING YOUR ANSWERS: Afterstudying the associated text, youshould be ready to answer thequestions in the assignment. Readeach question carefully, then selectthe BEST answer. Be sure to selectyour answer from the subject matterin the text. You may refer freelyto the text and seek advice and
information from others on problemsthat may arise in the course.However, the answers must be theresult of your own work anddecisions. You are prohibited fromreferring to or copying the answersof others and from giving answers toanyone else taking the same course.Failure to follow these rules canresult in suspension from the courseand disciplinary action.
ANSWER SHEETS: You must use answersheets designed for this course(NETPMSA Form 1430/5, Stock OrderingNumber 0502-LP-216-0100). Use theanswer sheets provided by EducationalServices Officer (ESO), or you mayreproduce the one in the back of thiscourse booklet.
SUBMITTING COMPLETED ANSWER SHEETS:As a minimum, you should complete atleast one assignment per month.Failure to meet this requirementcould result in disenrollment fromthe course. As you complete eachassignment, submit the completedanswer sheet to your ESO for grading.You may submit more than one answersheet at a time.
GRADING: Your ESO will grade eachanswer sheet and notify you of anyincorrect answers. The passing scorefor each assignment is 3.2. If youreceive less than 3.2 on anyassignment, your ESO will list thequestions you answered incorrectly
NRTC-i
and give you an answer sheet marked“RESUBMIT.” You must redo theassignment and complete the RESUBMITanswer sheet. The maximum score youcan receive for a resubmittedassignment is 3.2.
COURSE COMPLETION: After you havesubmitted all the answer sheets andhave earned at least 3.2 on eachassignment, your command should giveyou credit for this course by makingthe appropriate entry in your servicerecord.
NAVAL RESERVE RETIREMENT CREDIT: Ifyou are a member of the NavalReserve, you will receive retirementpoints if you are authorized toreceive them under current directivesgoverning retirement of Naval Reservepersonnel. For Naval Reserveretirement, this course is evaluatedat 3 points. (Refer to BUPERSINST1001.39 for more information aboutretirement points.)
STUDENT QUESTIONS: If you haveq u e s t i o n s c o n c e r n i n g t h eadministration of this course,consult your ESO. If you havequestions on course content, you maycontact NETPDTC at:
DSN: 922-1501Commercial: (904) 452-1501FAX: 922-1819INTERNET:[email protected]
COURSE OBJECTIVES: In completingthis nonresident training course, youwill demonstrate a knowledge of thesubject matter by correctly answeringquestions on the following subjects:
Communications Hardware, andSatellites and Antennas.
NRTC-ii
Naval courses may include several types of questions--multiple-choice, true-false, matching, etc. The questions arenot grouped by type but by subject matter. They are presented in the same general sequence as the textbook materialupon which they are based. This presentation is designed to preserve continuity of thought, permitting step-by-stepdevelopment of ideas. Not all courses use all of the types of questions available. You can readily identify the type ofeach question, and the action required, by reviewing of the samples given below.
MULTIPLE-CHOICE QUESTIONS
Each question contains several alternative answers, one of which is the best answer to the question. Select the bestalternative, and blacken the appropriate box on the answer sheet.
SAMPLE
s-l. The first U.S. Navy nuclear-powered vesselwas what type of ship?
1. Carrier2. Submarine3. Destroyer4. Cruiser
Indicate in this way on your answer sheet:
TRUE-FALSE QUESTIONS
Mark each statement true or false as indicated below. If any part of the statement is false, the entire statement isfalse. Make your decision, and blacken the appropriate box on the answer sheet.
SAMPLE
s-2. Shock will never be serious enough to cause Indicate in this way on your answer sheet:death.
1. True2. False
MATCHING QUESTIONS
Each set of questions consists of two columns, each listing words, phrases or sentences. Your task is to select theitem in column B which is the best match for the item in column A. Items in column B may be used once, more thanonce, or not at all. Specific instructions are given with each set of questions. Select the numbers identifying the answersand blacken the appropriate boxes on your answer sheet.
SAMPLE
In answering questions s-3 through s-6, SELECT from column B the department where the shipboard officer incolumn A functions. Responses may be used once, more than once, or not at all.
s-3.s-4.s-5.s-6.
A. OFFICER B. DEPARTMENT
Damage Control Assistant 1. Operations DepartmentCIC Officer 2. Engineering DepartmentDisbursing Officer 3. Supply DepartmentCommunications Officer
Indicate in this way on your answer sheet:
4. Navigation Department
NRTC-iii
ASSIGNMENT 1Textbook Assignment: “Communications Hardware,” chapter 1, pages 1-1
through 1-18.
1-1. What are a lot ofcommunications failuresascribed to?
1. Equipment failure2. Poor administration3 Technical problems4. Operator error
1-2. Who determines the level ofreadiness and preparationthat a deploying ship shouldmaintain?
1. The commanding officer2. The executive officer3. The type commander4. The fleet commander in
chief
1-3. What it the most efficientmethod of ensuring that allstep-by-step preparationsare completed beforedeploying?
1. A check-off list2. A visual check of all
stores3. A review of all locally
produced SOPs4. A review of all
inventory lists
1-4. What publication providesthe minimum number ofcheck-off sheets?
1. NTP 42. NWP 4 (NWP 6-01)3. CMS 14. CMS 5
1-5. For long-range directionfinding, medium-rangecommunications andnavigation communications,which of the followingfrequencies is normallyused?
1. VLF2. UHF3. SHF4. LF
1-6. The LF receiver is fed intowhat component in alow-frequency receiversystem?
1. Receiver transferswitchboard
2. AN/SRA-583. FCC-1004. UYK-20
1-7. The AN/UCC-1, when used toconvert AF to dc for use byteleprinters, functions aswhat type of equipment?
1. Converter2. Multicoupler3. Converter comparator4. Patch panel
1
1-8. What is the difference, ifany, between a black dcpatch panel and a red dcpatch panel?
1. The black dc patch panelis located closer to theantenna multicouplerthan the red dc patchpanel.
2. The black dc patch panelallows the operator topatch the signal to anycryptoequipment, and thered dc patch panelrestricts the printerselected to plainreadable text orlanguage
3. The black dc patch panelallows for patching thesignal into anycryptoequipment, and thered dc patch panelcompletes the loop for asingle feedback circuit
4. None
1-9. What frequency range isprimarily for mobile andmaritime units?
1. UHF2. SHF3. HF4. VLF
1-10. Aeronautical radionavigation, mobilecommunications, boat crews,and radar use which of thefollowing frequency bands?
1. ELF2. HF3. VLF4. VHF
1-11.
1-12.
1-13.
1-14.
When using the VHF system,the receiver transferswitchboard will either sendthe output to the C-1138Radio Set Control or whichof the following?
1. The speaker amplifieronly
2. The speaker amplifier orboth units
3. The handset controller4. The receiver transceiver
The UHF band is located inwhat frequency range?
1. 30 to 300 GHz2. 300 MHz to 3 GHz3. 3 to 30 MHz4. 300 kHz to 3 MHz
In the UHF system the outputof the patch panel isconnected to the transmitterside of the transceiver andthen connected to which ofthe following?
1. The C-1138 Radio SetControl
2. The RPU3. The antenna coupler4. The voice handset
Where in the UHF receivesystem will the voice signalbe decrypted into plainlanguage?
1.
2.
3.
4.
Prior to the transferswitchboardIn the secure voiceequipmentAfter the secure voiceequipmentAt the secure voiceremote phone unit
2
1-15.
1-16.
1-17.
1-18.
In what section of NTP 2will you find informationpertaining to the Navy’s SHFsatellite system?
1. One2. Two3. Three4. Four
What is/are the warningsign(s), if any, that areattached to black patchpanels?
1. UNCLAS ONLY2. ENCRYPTED TRAFFIC ONLY3. BLACK PATCH PANEL and
UNCLAS ONLY4. None
When equipment arepermanently wired togetherbecause they are used inconjunction with each other,this arrangement is called
1. normal-through2. wired3. tied4. junctions
When you increase the numberof circuits on a sideband,this is known as what?
1. Increased sidebandcomplements
2. Multiplexing3. Frequency splitting4. Sideband modulating
1-19.
1-20.
1-21.
1-22.
1-23.
When using the AN/UCC-1, youare using frequency-divisionmultiplexing for what typesof radio circuits?
1. High volume2. Time-division3. Transmitting4. Single- and
double-sideband
In what type of publicationswill you locate informationand instructions on the useof cryptoequipment?
1. KAOs2. NTPs3. NWPs4. ACPs
Define “tone package.”
1. Transmission withmultiplexed channels
2. Signals from individualcircuits
3. Negative bias signals4. Attenuators, keyers, and
converters in one system
What is the total number ofnarrowband channels that canbe obtained from a terminal?
1. 122. 133. 154. 16
Using the fleet broadcastsystem, there are 16channels, 2 of which carrythe same information. Thisprocess is called what?
1. Doubling2. Double duty3. Twinning4. Matching
3
1-24. What are the differentmethods of operation inship-shore mode?
1. Duplex, simplex, andsemiduplex
2. Simplex, semiduplex andtriplex
3. Duplex, semiduplex andquadplex
4. Simplex, duplex, triplexand quadplex
1-25. When you can use acommunications equipment toboth transmit and receivesimultaneously, this isknown by which of thefollowing terms?
1. FSK (phase shift keying)2. TDM (time-division
multiplexing)3. FDX (full duplex)4. HFX (half duplex)
1-26. What is the normal reasonthat a ship would use thesimplex method?
1. Equipment casualties2. Not ample equipment
onboard3. Abundance of circuits
online4. Transmission by NECOS of
a SAR request
1-27. A ship using a simplexsystem has to call up theshore station to passmessage traffic. If theship cannot raise the shorestation after the secondattempt, what is the usualprocedure?
1. Check the equipment2. Repeat the call-up3. Try standby frequency4. Attempt to contact
another station
1-28. What is the purpose of thesecure voice worldwide voicenetwork?
1. To be able tocommunicate anywhere inthe world by voice
2. For ships to be able totalk to shore stations
3. To hook together alltypes of commands intoone voice network
4. To provide securereal-time, voicecommunications betweenboth afloat commands andoperational commandersusing HF or satelliteconnectivity
1-29. What is the total number ofFLTCINCs that control thenetwork of secure voice areacontrol stations?
1. One2. Two3. Three4. Four
4
1-30.
1-31.
1-32.
1-33.
What does a full-periodtermination accomplish?
1.
2.
3.
4.
Provides communicationsbetween shore stationsand afloat commandsAllows a ship to sendtraffic to any shorestation along its trackfor retransmissionProvides exercisecontrol over a ship fora greater period of timeAllows a ship and an
For what reason will aCOMMSPOT report besubmitted?
aircraft to communicateover greater distances
What is the normal lead timethat a termination requestmust be submitted for afull-period termination?
1. 12 hours2. 24 hours3. 36 hours4. 48 hours
In what publication will youfind details of what must beincluded in a terminationrequest message?
1. NTP 32. NTP 43. NWP 4 (NWP 6-01)4. NWP 6 (NWP 4-02)
Once the full-periodtermination period issecured, what type ofmessage must be sent tocancel the termination?
1. TSR2. COMMSPOT3. COMMSHIFT4. Off-the-air
5
1-34. System back-to-backoff-the-air testing must becompleted what total numberof hours prior to atermination activation?
1. 12 hrs2. 24 hrs3. 48 hrs4. 72 hrs
1-35.
1.
2.
3.
4.
Any time unusualcommunicationsdifficulties areencounteredWhen a ship is havingproblems passing trafficto a shore stationWhen a shore station cannot raise a ship for achannel checkWhen an aircraft wishesto pass vital messagetraffic for a Task Force
1-36. To prepare a JINTACCSformatted COMMSPOT message,you should refer to whatpublication forinstructions?
1. NTP 42. CMS 63. NWP 10-1-13 (NWP 1-03
Supp-1 )4. NWP 10-10-10 (NWP
1-03.1)
1-37. Primary ship-shore circuitsuse what type of encryptedteleprinter nets?
1. TDM/TDK2. FDX/HDX3. ARK/MRK4. PSK/FSK
1-38.
1-39.
1-40.
1-41.
1-42.
Where are the frequenciesfor PRI S/S circuits listed?
1. CIBs2. TSRs3. NAVADMINs4. Local SOPs
What does the use ofOTAT/OTAR procedures allow acommand to do?
1. Not carry any cryptokeying material
2. Reduce the amount ofpaper keying material onboard
3. Relieve the operator ofever using SF-153 forms
4. Reduce the number of CMScustodians required
In what publication do youfind detailed OTAT/OTARprocedures?
1. CMS 12. CMS 63. NAG 164. NTP 4
Where was the use andverification of OTAT/OTARprocedures first utilized?
1. Desert Shield/Storm2. Vietnam3. Bosnia4. Cuba
What type of message traffictakes priority over allother types?
1. Immediate2. AMCROSS3. Distress4. SOSUS
1-43.
1-44.
1-45.
1-46.
1-47.
6
Who may authorize thetransmission of unclassifieddistress messages onnational or internationaldistress frequencies?
1. The commanding officer2. The officer in tactical
control3. The communications
officer4. The communications watch
officer
If your ship is in distressand traveling with others,to whom will you transmityour distress message?
1. FLTCINC2. OTC3. NECOS4. CNO
If you are in a lifeboat;which of the followingfrequencies will you use?
1. 500 kHz2. 2182 kHz3. 8364 kHz4. 121.5 MHz
What is the internationalworldwide SAR frequency forvoice?
1. 138.78 MHz2. 123.1 MHz3. 282.8 MHz4. 172.5 MHz
Navy ASW aircraft assignedto a SAR mission monitor onwhat frequency?
1. 123.1 MHz2. 138.78 MHz3. 282.8 MHz4. 172.5 MHz
1-48.
1-49.
1-50.
Who is in control of the 1-51.distress message trafficfrequency during anemergency?
1. The station in distress2. The first ship on the
scene3. The first aircraft on
the scene4. The senior international
officer at the scene
When equipment and manpowerwill allow, what frequenciesdoes a watch stationnormally listen to?
1-52.1. Worldwide timing2. GMT3. Distress4. Secvox
What is the usual cause ofsystem degradation?
1. Dirty jacks2. Small contributing
factors3. Power outages4. Degraded patch cords
What is the primary functionof the quality monitoringprogram?
1. To ensure that all PMSchecks are completed online
2. To monitor the endresults from all QC jobs
3. To verify all paper workassociated with levels,signals, and analysisforms
4. To direct measurement ofsignal qualitycharacteristics
What is the nomenclature ofthe Quality Monitoring set?
1. AN/SSQ-882. AN/QMS-233. Spectrum Analyzer 1344. Spectrum Monitor 143
7
ASSIGNMENT 2Textbook Assignment: “Satellites and Antennas,” chapter 2, pages 2-1
through 2-31.
2-1. What is the reason for thedevelopment of the satellitecommunication (SATCOM)system?
1.
2.
3.
4.
Provides a long range,jam-proof communicationsystemFulfills the militaryrequirements forreliable, high-capacity,secure andcost-effectivetelecommunicationsIs line-of-sight andEMCON proofReplaces all basebandfrequencies during HEROand AUTOCAT
2-2. Satellites provide analternative to which of thefollowing facilities?
1. Fixed groundinstallations
2. Airborne command posts3. GPS4. AMCC vans
2-3. What antenna is used withthe AN/WSC-3 transceiver andis employed primarilyonboard ships?
1. AN/SSR-12. OE-82C/WSC-1(V)3. Whip4. Quarter-wave
2-4. Where is the OE-82/WSC-1(V)mounted?
1. Main stack2. Fore mast3. On a pedestal4. To the skin of the ship
2-5.
2-6.
2-7.
2-8.
2-9.
8
What is the receivingfrequency band for theOE-82C/WSC-1(V)?
1. 248 - 272 MHz2. 275 - 300 MHz3. 310 - 315 MHz4. 2 - 4 GHz
What is the total number ofAS-2815/SSR-1 antennas in anAN/SRR-1 receiver system?
1. One2. Two3. Three4. Four
The AS-2815/SSR-1 antennasemployed in the 240 to 315MHz frequency range areutilized to receive whattype of broadcasts?
1. CUDIXS2. Common Channel3. FFN4. Fleet
What is the physical size ofthe newer satelliteparabolic antennas?
1. 6 in2. 8 in3. 12 in4. 18 in
Name the three types of U.S.Navy communicationssatellites.
1. MARISAT, RCA, and ATT2. GAPFILLER, FLTSATCOM,
and LEASAT3. ORION, EROS and ZEUS4. DANTES, ORION, and
HERMES
What type of orbits do U.S.1-10.
2-11.
2-12.
2-13.
2-14.
Navy satellites use?
1. Geostationary2. Geosynchronous3. Polar4. Random
MARISAT channels were brokendown into three UHFchannels, two narrowbandchannels, and what totalnumber of wideband channels?
1. One2. Five3. Three4. Six
The 500-kHz band GAPFILLERsatellites provide whatnumber of 75 baud ship-shorecommunications channels?
1. 152. 203. 354. 50
What does the UHF receiverseparate on the GAPFILLERsatellite?
1. The receiver andtransmitter band
2. Intermediate frequenciesand low frequencies
3. Secure voice andnon-secure voicechannels
4. Red and Black channels
What are the FLTSATCOMsatellites’ longitudinalpositions?
1. 95° W, 65° E and 150° E2. 25° E, 35° W, 05° N and
55° E3. 100° W, 72.5° E, 23° W,
and 172° E4. 22° W, 152° E, 06° E,
and 21° N
2-15. What is the maximumRF-channel capability on theFLTSATCOM satellite?
1. 102. 153. 234. 35
2-16. On the FLTSATCOM satellite,channel 1 of the 25-kHzchannels is used for whatpurpose?
1. Timing2. Fleet broadcast3. Weather4. DSN
2-17. What is the position of theLANT (L-1) LEASAT?
1. 15° W2. 105° W3. 72.5° E4. 53° E
2-18. Each LEASAT provides whattotal number of (a)communications channels and(b) transmitters?
1. (a) 10 (b) 42. (a) 11 (b) 63. (a) 13 (b) 94. (a) 15 (b) 11
2-19. One of the UHF downlinkchannels is used for theFleet Satellite Broadcastdownlink. What is itsfrequency?
1. 10 kHz2. 15 kHz3. 20 kHz4. 25 kHz
9
2-20.
2-21.
2-22.
2-23.
AN/WSC-6(V)4 terminals willreplace which of thefollowing terminals onaircraft carriers?
1. TADIX2. QUICKSAT3. SUBSAT4. FSC-78
What are the two types ofsatellites?
1. Active and passive2. Passive and module3. Active and repeater4. Repeater and passive
An active satellite and twoEarth terminals isconsidered what type ofoperational link?
1. Standard2. Optimal3. Universal4. Typical
Normally, a satellite’sorbit is elliptical orcircular, while its inclineis polar, equatorial, orwhich of the following?
1. Angle2. Attitude3. Inclined4. Slant
2-24. A satellite communicationssystem includes installedcommunications receivers andtransmitters and what othercomponents?
1.
2.
3.
4.
Two Earth terminalsready to transmit andreceive satellitesignalsTwo Earth terminalsequipped with receiverand satellitetransceiversThree Earth terminals,two with receivers andone with transceiversThree Earth terminals,one with receivers andtwo with UHFtransmitters
2-25. What does a narrow uplinktransmission beamwidthprovide the capability todo?
1. High intercept problems(HIP)
2. Low probability ofintercept (LPI)
3. High detection rates(HDR)
4. Exploitation, detection,and location (EDL)
2-26. An HPA or MPA, LNA, up anddown converters, and afrequency standard are knownby what name?
1. Power group2. Digital set3. Binary set4. Radio group
2-27. What is the Navy’s standardSATCOM broadcast receiversystem?
1. AN/FSC-792. AN/SSR-13. CV-1234. ARC-143B
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2-28.
2-29.
2-30.
2-31.
2-32.
Communications subsystemsand satellites areinterfaces using which ofthe following equipments?
1. AM-65342. TD-10633. AN/FSC-794. CV-123
What is the operatingbandwidth of the AN/FSC-79?
1. 7 to 8 GHz2. 9 to 11 GHz3. 10 to 12 GHz4. 11 to 15 GHz
In what mode of operation isthe AN/WSC-3 when it uplinksin the 292.2- to 311.6 MHzbandwidth and downlinks inthe 248.5- to 270.1 MHzband?
1. TDM2. Fleet communication3. SATCOM4. Remote
The AN/ARC-143 UHFTransceiver, used for ASWIXScommunications, has how manyparts?
1. Five2. Two3. Three4. Four
What type of system providescommunications links, viasatellite, between mobileunits and shore commands?
1. FLTSATCOM2. LEASAT3. NOVEMBER4. DELTA
2-33. What is used as theinterface between CUDIXS(shore-based) and the FleetBroadcast System?
1. SNAP III2. NAVMACS3. GLOBAL HICOM4. DAMA
2-34. SSIXS is used to transmitand receive message trafficbetween what two types ofusers?
1. VP aircraft and ASCOMMs2. Fleet Marine Forces and
attack helos3. SSN/SSBN submarines and
shore stations4. SSN/SSBN submarines and
Battle Group commanders
2-35. ASWIXS is used as acommunications link betweenASW planes during operationsand what other type ofcommands?
1. Shore stations2. Battle Group commanders3. Positioning aircraft4. SPECOMMs
2-36. The subsystem that expeditesstatus reporting andmanagement of the FLTSATCOMsystem assets is calledwhat?
1. TACINTEL2. NECOS3. Control4. Fleet Flash Net
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2-37.
2-38.
2-39.
2-40.
DAMA was developed for whatpurpose?
1. To break out the securevoice circuit from allother transmissions
2. To remove all residuetraces that allow forjamming
3. To fully automate andlink data systems withthe net
4. To multiplex severalsubsystems onto onesatellite channel
What other multiplexingmethod, if any, does theNavy utilize besidesfrequency-division?
1. Time-division2. Shift-division3. Split time-division4. None
When HERO condition andEMCON restrictions are set,what are the radiofrequencies (RFs) that areprohibited from use?
1. 2 - 3 GHz2. Below 30 MHz3. 300 - 2568 kHz4. Above 3000 kHz
Who are the majorparticipants on the FFN?
1.
2.
3.4.
Senior operationalstaffs onlySenior operationalstaffs and designatedsubscribersNATO and CINCs onlyThe Joint Chiefs ofStaff and their ForceCommanders
2-41.
2-42.
2-43.
2-44.
2-45.
2-46.
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An antenna can both transmitand receive energy. Thisability is known by whatterm?
1.2.3.4.
ReciprocityFeed pointTransducanceStagnation
The point on an antennawhere the RF cable isattached is called what?
1. Focal point2. Dummy point3. Feed point4. Center point
What type of antennaradiates efficiently in onlyone direction?
1. Bidirectional2. Omnidirectional3. Polarized4. Unidirectional
What is the “perfect” SWRthat can be theoreticallyachieved?
1. One-to-one2. Two-to-one3. Three-to-one4. Four-to-one
Energy reflected back to thefeed point is known by whichof the following terms?
1. Impedance point2. Reflected waves3. Oscillation point4. Deflected waves
Electromagnetic waves travelin free space at what rate?
1. 1,324,000 miles persecond
2. 946,000 miles per second3. 518,000 miles per second4. 186,000 miles per second
2-47. Antennas are referred to inlengths. There is fullquarter, and what otherlength?
1. Half2. Eighth3. Third4. Sixteenth
2-48. Wire rope (fan) antennas areused for what range offrequency coverage?
1. 30 kHz to 299 kHz2. 300 kHz to 30 MHz3. 2 - 20 GHz4. 3 - 30 kHz
2-49. The conical monopole antennais used in what type ofcommunications?
1. LF2. MF3. HF4. VHF
2-50. The AN/SRA-12 allows forwhat total number of RFchannels in the 14-kHz to32-MHz range?
1. Five2. Two3. Seven4. Four
2-51. What is/are the objectives
1.
2.
3.
4.
of tuning an antenna?
Tune out impedances andmatch length tofrequency radiatedPhysically ormechanically move theantennaExhibit and multiplexits impedanceClean up the wavegeneration and use wavepropagation
2-52. Which Navy standards, ifany, have control over thesafety of personnel goingaloft?
1. NAVSAFCEN instructions2. NAVOSH requirements3. MILSTDs4. None
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