T9-1

Chapter 9 – Special Operations

• VHF and UHF Operation– Repeater Operations, Autopatch and Linking

– APRS Operations and Digipeaters

– Simplex Operation

• Amateur Satellite Operations• Earth-Moon-Earth (EME) Communications• Image Communications• One-Way Communications

T9-2

Repeaters

• VHF/UHF repeaters extend communication range by receiving a signal and retransmitting it.

• A repeater receives on one frequency (input) and transmits on a separate frequency (output) at the same time.– The frequency difference between the repeater input

and output frequencies is called the offset.– The standard repeater frequency offset for a repeater on

the 2 meter band is 600 Khz.

• Some repeaters can receive on one band and transmit on another band (crossband repeaters).

T9-3

Repeaters

T9-4

Repeater Operation

RX: 146.82

TX: 146.22

RX: 146.82

TX: 146.22

RX: 146.22

TX: 146.82

Repeater

Ham A

Ham B

T9-5

Band Plan – 2 meters144.0 145.0 146.0 147.0 148.0

OutIn OutIn Out In

RepeaterCW SSB, Weak Signal FM Simplex

Frequency Usage

144.00-144.05 EME (CW)

144.05-144.10 General CW

144.10-144.20 EME & SSB

144.200 National SSB Calling

144.20-144.275 SSB Operations

144.275-144.300 Beacons

144.30-144.50 OSCAR Subband

144.50-144.60 Linear Translator Inputs

144.60-144.90 Repeater Inputs

144.90-145.10 Weak Signal SSB

145.10-145.20 Linear Translator Outputs

Frequency Usage

145.20-145.50 Repeater Outputs

145.50-145.80 Misc Experimental

145.80-146.00 OSCAR Subband

146.01-146.37 Repeater Inputs

146.40-146.58 FM Simplex

146.52 National FM Calling

146.61-146.97 Repeater Outputs

146.700-147.39 Repeater Outputs

147.42-147.39 FM Simplex

147.60-147.99 Repeater Inputs

T9-6

Repeaters (Cont’d)

• Some crossband repeaters can operate in duplex mode to allow a user to talk and listen at the same time (similar to a telephone).

• Most repeaters have “open” access; however, some repeaters are operated as “closed” repeaters.

• Repeaters may require the transmission of a subaudible tone or tones for access to prevent interference by extraneous transmissions.– Called CTCSS (Continuous Tone Coded Squelch

System) or PL (Private Line) tones.

T9-7

Repeaters (Cont’d)

• Repeaters identify using Morse code or voice recordings.

• Repeater frequencies are selected through consultation with frequency coordinators.

• Repeater frequencies, by geographic location, can be found the in The ARRL Repeater Directory.

• Amateur television (ATV) repeaters operate on the 70 cm UHF band.

• Most repeaters are funded by amateur radio clubs and their members.

T9-8

Rochester Voice Repeaters

Call Output (MHz) Input (MHz) Tone (Hz)

VHF 2m Repeaters

WØMXW/R 146.625 146.025(-) 100

WØMXW/R 146.820 146.220(-) 100

WØEAS/R 147.255 147.855(+) 100

UHF 70cm Repeaters

KGØBP/R 442.750 447.750(+) 110.9

WØMXW/R 443.850 448.850(+) 71.9

Not on test

Note: RARC WØMXW/R repeaters 146.82 and 146.625 may require use of 100 Hz access tone.

T9-9

Repeater Operation

• Making your first transmission on a repeater is as simple as signing your call.

• Pause between transmissions to allow other stations to break in by giving their call sign.

• The repeater courtesy tone is a beep which sounds a second or two after each transmission to permit other stations to transmit their call signs.

• A time-out timer prevents the repeater from transmitting continuously.

T9-10

Repeater Autopatch

• Allows repeater users to make local telephone calls through the repeater system.

• Touch-tone tones are used to access, dial phone numbers, and terminate the autopatch operation.

• Some repeaters provide autopatch “speed-dial” numbers.

• Never use the repeater autopatch for business communications.

T9-11

Repeater Internet Linking

• Amateur repeaters can be linked together using the internet “Voice Over IP” capabilities.

• VOIP internet linked repeaters allow amateurs to communicate to other amateurs across the country and around the world.

• Echolink is a popular repeater linking technology.– KØRGR operates a Echolink node on the RARC

146.625/146.025 repeater in Rochester.

– For information on Echolink and using the local Echolink node, see the Echolink page on www.rarchams.org.

T9-12

Repeater Internet Linking

RepeaterHam

KØRGR/LEcholink

Node

Internet

HamVoIP

Repeater

EcholinkAccess via Internet

EcholinkNode

T9-13

APRS Digipeaters

• Digital repeaters (digipeaters) are used to relay digital packets of information between amateur radio stations.

• The Automatic Position Reporting System (APRS) is a digital packet system for relaying geographic position reports, messages, and weather reports between amateur radio stations.– APRS digital packets may be relayed via digipeaters,

satellites, ISS, or the internet.

– APRS position reports are often plotted on computer maps for tracking and messaging.

Not on test.

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APRS Position Report Display

APRS position report displayed on Kenwood D700 transceiver.

T9-15

Automatic Position Reporting System

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APRS Digipeaters (Cont’d)

• APRS gateway digipeaters are connected to the internet and relay APRS digital packets to and from the internet.

• APRS amateur stations and digipeaters typically use the national APRS frequency of 144.39 MHz.

• For information on APRS and Rochester digipeaters, see the APRS page at www.rarchams.org

Not on test.

T9-17

VHF/UHF Simplex Operation

• Stations are operating simplex when they are communication directly with each other.

• If two stations using a repeater can hear each other on the repeater input frequency, then they should be able to operate on a simplex frequency.

• National simplex calling frequencies have been defined on the VHF/UHF bands.– The national simplex calling frequency on the 2 meter

band is 146.52 MHz.

T9-18

Amateur Satellite Operations

• Orbiting Satellites Carrying Amateur Radio (OSCARs) are amateur radio satellites.

• Any licensed amateur can operate through a satellite using the VHF and UHF bands.

• A satellite’s orbit is usually shaped like an ellipse.– Perigee is the closest approach to Earth

– Apogee is the farthest distance from Earth

– The orbit can be mathematically calculated using Keplerian element parameters.

T9-19

Amateur Satellite Operations (Con’t)

• The Doppler effect shifts the apparent frequency of a satellite transmission due to the relative motion between the satellite and earth station.– As the satellite moves closer, the frequency is higher.

– As the satellite moves away, the frequency is lower.

• The International Space Station (ISS) operates amateur stations in voice and packet modes.– Due to the fairly low, circular orbit, the ISS station can

only be worked 4 to 6 minutes per pass by an Earth station.

T9-20

Earth-Moon-Earth (Moonbounce)

• Amateur stations reflecting signals off of the moon are using EME communications.

• Stations can be more than 11,000 miles apart on Earth.

• Due to the extremely weak reflected signals, most EME operations use Morse code.

• High path losses require the use of high power amplifiers and high-gain antennas (stacked Yagi or collinear).

T9-21

Amateur Television (ATV)

• ATV, or “fast scan television,” uses the same standards, or frame rate, as broadcast television.

• The 70 cm band is the lowest frequency band where ATV operations is permitted.

• A cable-ready television set can receive ATV frequencies on the 70 cm band.

• ATV repeaters are used to expand the communication range.

T9-22

Slow-Scan Television (SSTV)

• Images are transmitter by converting the image into transmitted audio tones.

• SSTV is popular on the 20 meter HF band using SSB emission.

• Also used on the 2 meter band using simplex or FM voice repeaters.– As a matter of courtesy, you should request permission

to use a FM repeater for SSTV communication from the repeater owner.

T9-23

Beacon Stations

• Beacon stations are transmitters primarily used for the study of radio-wave propagation or other experimental activities.

• The transmitter power of a beacon must not exceed 100 watts.

• All technician and higher license classes can operate a beacon station.

• Beacon stations are limited to parts of the 28, 50, 144, 222, and 432 Mhz bands plus all bands above 450 Mhz.

T9-24

Telecommand

• Telecommand operation is a one-way transmission to initiate, modify or terminate functions of a device at a distance.– Controlled devices may be models, amateur satellites or

remote controlled amateur stations.

• FCC rules do not require identification during telecommand of a model craft.– The transmitter must contain a label with the station

call sign and licensee’s name and address.

– Maximum transmitter power is limited to 1 watt.