Satellite Manual

8/2/2019 Satellite Manual

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Satellite Communication Page 1

Experiment 1

Objective:

Understanding Basic concepts of Satellite communication

Theory:

Sinusoidal electromagnetic waves (E/M waves) All radio and television signals

consists of electrical and magnetic fields which in free space travel at speed of

light (approx 3 108 meters/seconds), these waves consists of an Electric field (E),

measured in amperes/meter, the E and H field components are always at right

angle to each other and the direction of travel is always at right angles of both

fields. The amplitudes vary sinusoidal as they travel through space. In fact it is

impossible to produce a non sinusoidal E/M wave!(the importance of this

statement will be grasped more easily when modulation is discussed.)

The SineWave:

Cycle: One complete electrical sequence Peak Value (Vp): Maximum positive or

negative value also called amplitude.

Period (t): Time to complete one cycle

Frequency (f): Number of cycles per second in Hertz.

(One hertz = one cycle per second). It follows that period and frequency are

reciprocals of each other. T=1/f

Commonly used multiplies of hertz are:

Kilohertz (KHz) =103 Hz = 1000Hz

Megahertz (MHz) = 106 Hz = 1000000Hz

Gigahertz ( GHz) = 109 Hz = 1000000000Hz

RMS Value:

This is 0.707 of the peak value and unless otherwise stated, any reference to

voltage or current in technical literature is normally taken to mean this value for


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Example, the supply mains in UK is a sinusoidal variation, stated to be '240 Volts'

so the peak value is 240/0.707 = 339 volts.

Angular Velocity (w):

This is an indirect way of expressing the frequency W = 2f rad / sec Instead of

considering the no of complete cycles angular velocity is a measure of how fast the

vector angle is changing. The Voltage equation of sine wave which gives the

instantaneous value (v) of a sine wave at any point in the cycle is given by: v =

Vpsin for a convenience and brevity, the 2F part is often lumped together and

given the title of angular velocity().Using this notation the equation of sine wave

can be written as: v =VP sint

Wavelength:

Since E/M waves at a known velocity vary sinusoidal, it is possible to consider

how far a wave of given frequency (f) would travel during the execution of one

cycle. Denoting the speed of light as c the wavelength () is given by: = c / f

From this, it so as clear that the higher the frequency the shorter the wavelength

Satellite broadcasting employs waves in this order of 10GHz frequency so the

order of wavelength can be calculated as follows:

= (3 108) / (10 109)

= 3 10-2m = 3 cm.

In practice the frequencies used are not necessarily a nice round figure like 10 GHz

Nevertheless; the wavelength in present use invariably works out in terms of

centimeters. The enormously high frequencies are used in satellite broadcasting?Before this can be answered it is necessary to understand some fundamentals laws

to broadcasting of information, whether it be sound or picture information.

Carrier frequency:

For simplicity, assume that it is required to transmit through space a 1000Hz audio


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signal, in theory an electrical oscillator and amplifier could be rigged up and tuned

to 1000 cycles per sec. And the output fed to a piece of wire acting as primitive

aerial. It is an unfortunate fact of nature that of nature that for reasonably efficient

radiation a wire aerial should have a length somewhere in order of wavelength of

1000 Hz using the equation given above:

= c / f = 3 108 / 103 = 3 105 meters.

= 300000 m which is about 188 miles.

Apart from the sheer impractically of such an aerial, waves at these low

frequencies suffer severe attenuation due to ground absorption. Another important

reason for using high frequencies is due to the considerations of bandwidth, whichis treated later. This solution is to use a high frequency wave to carry the signal but

allow the Intelligence (the 1000 Hz in our example) to modify one or more of its

characteristics. The high frequency wave is referred to as the carrier (Fc) simply

because it carries the information in some way the method of impressing this low

frequency information on to carrier is called modulation. There are two main

types amplitude modulation (AM) and frequency modulation (FM).

Amplitude modulation:

The low frequency modulating signal is made to alter the amplitude of carrier at

the transmitter before the composite waveform is sent to the aerial system. If the

amplitude of the modulating signal causes the carrier amplitude to vary between

double its unmodulated height and zero, the modulation is said to be 100 percent.

terrible distortion results if the modulation amplitude is ever allowed to exceed 100

percent.

Modulation factor:

This is the ratio of modulation amplitude (Vm) to carrier amplitude (Vc)

m = Vm / Vc


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When m = 1 the modulation is 100 percent, although 100 percent is an advantage it

is too dangerous in practice, due to the possibility of over modulation, so 80% (m =

0.8) is normally considered the safe limit.

Sidebands:

Although the modulating signal is simple sinusoidal waveforms, in practice it will

be more complex. Thus the envelope of the waveform will be non-sinusoidal. The

unmodulated carrier sine wave has the instantaneous form: v = Vp sinct But the

amplitude of this wave (Vp) is made to vary by the modulating frequency which

causes Vp to have the form: Vp = Vm sint Substituting this expression in the first

equation gives: v = Vmsinct. sinctWe know one of the trigonometric identities

Sin A Sin B= Cos (AB) Cos (A+B)

So it follows that the modulated carrier waveform splits up in space into three pure

Sinusoidal components:

a) The carrier frequency

b) The frequency equal to the sum of the carrier and modulating frequencies. This

is called Upper sideband.

c) The frequency equal to the difference of the carrier and modulating frequencies.

This is called lower sideband.

If the carrier frequency is 1000000 Hz and the modulating frequency is 1000 Hz

then the upper sideband is 1001000 Hz sine wave and lower sideband is 999000

Hz. In practice the modulating frequency will seldom be anything as simple as a

1000 Hz sine wave but more probably, may consists of speech or picture

information which contains a complex mixture of frequencies. For example, the

music frequency extends from about 20 Hz to about 18 KHz so, to transmit high

quality sound the upper sidebands would have to contain spread of frequencies


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extending from 20 Hz to 18 KHz above the carrier and the lower sidebands

frequencies extending 20 Hz to 18 KHz below the carrier. Television transmission

is more difficult because picture have a far greater information content than sound.

Wider the sidebands of transmission, greater space will occupy in the frequency

spectrum so broadcast stations geographically close together must operate on

frequencies well away from each other in order to prevent the interference from

their respective sidebands. Since television station occupy several MHz in the

spectrum, carrier frequencies are forced into ever higher and higher frequencies as

the number of stations fight for space. there are several novel solutions to the

overcrowding problem for example it is not essential to transmit both sidebands

since all the required information is contained in one of then, providing of course

the carrier is sent with it. Such transmission is contained in one of them, providing

of course the carrier is sent with it. Such transmissions are called SSB (single

sideband). An even more drastic curtailment is to reduce the carrier at the

transmitter to almost zero and use it to synchronize a locally generated carrier at

the receiving end a Technique known as single sideband vestigial carrier

modulation.

Frequency Modulation:

Whereas amplitude modulation alters the envelope in the vertical plane, frequency

modulation takes place in the horizontal plane, the amplitude of the carrier is kept

constant but the frequency is caused to deviate proportional to the modulating

amplitude.

Frequency Deviation:

The maximum amount by which the carrier frequency is increased or decreased by

the modulating amplitude is called the frequency deviation. It depends up on the

amplitude (peak value) of the modulating voltage. In the case satellite

broadcasting, the signal beamed down to earth has a typical frequency deviation of


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about 16 MHZ and the bandwidth occupied by the picture information is

commonly about 27 MHz.

Modulation index:

This is the ratio of the frequency deviation (f) to the highest modulating

frequency (fm) M =f / fm In contrast with amplitude modulation, the modulation

index is not necessarily restricted to maximum of unity.

Pre-emphasis (de-emphasis) improvement:

Since the noise power density of a receiver demodulator output increases with

frequency, high frequencies are boosted or pre-emphasized prior to transmission,

when the signal is subsequently demodulated in the receiver the signal and itsacquired noise is deemphasized or reduced by an equal amount the overall effect is

to reduce the noise component and leads to typical improvement in S/N of 2dB for

PAL I signals or 2.5 dB for NTSC M signals.

Noise:

An unwanted signal which interferes with reception of the desired information.

Noise is often expressed in degrees Kelvin or in decibels.

Decibel (dB):

The logarithmic ratio of power levels used to indicate gains or losses of signals.

Decibels relative to one Watts, milliWatts and milliVolt are abbreviated as dBW,

dBM and dBmV, respectively. Zero dBmV is used as the standard reference for all

SMATV calculations. dB =10 log P1/ P2 The sign of result is positive if p1 is

greater than p2 and negative if p1 is less than p2.

Voltage db:

Although dbs are normally used in conjunction with power ratio, it is sometimes


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convenient to express voltage ratio in db terms. dB = 20 log v1 / v2 The use of 20

instead of 10 is because power is proportional to the square of the voltage so the

constant is 20 instead of 10.

Ku-Band Satellite TV:

The microwave frequency band between approximately 11 and 13 GHz used in

Satellite broadcasting in European nations.

Clarke Belt:

The circular orbital belt at 22,247 miles above the equator, named after the writer

Arthur C. Clarke, in which Satellites travel at the same speed as the earth's rotation.

Also called the geostationary orbit.

Antenna:

An antenna may be defined in the following way. To radiate or receive

electromagnetic waves an antenna is required. Antenna or aerial is system of

elevated conductors which couples or matches the transmitter or receiver to free

space. A transmitting antenna connected to a transmitter by transmission line,

forces electromagnetic waves into free space which travel in space with velocity of

light. Similarly, a receiving antenna connected to a radio receiver, receives or

intercepts a portion of electromagnetic waves through space. Thus radio antenna is

defined as the structure associated with region of transition between a guided wave

and a free space wave or between a free space wave and guided waves. The official

definition of antenna according to the institution of electrical and electronics

engineers is the simply a "means for radiating or receiving radio waves". A

Satellite antenna intercepts the extremely weak microwave transmission from a

targeted Satellite and reflects the signal to its focal point, where the feed horn is

placed. This is the process that concentrates the signal so that the necessary power

is available for subsequent electronic components. The quality of a Satellite

antenna, often simply called a dish, is determined by how well it targets a Satellite


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and concentrates the desired signal and by how well it ignores unwanted noise and

interference. Dishes must be durable and able to withstand winds as well as other

natural and manmade forces. In order to be able to compete in the marketplace,

they also must be aesthetically pleasing and affordably priced.

Dish Antenna:

To receive signal from the Satellite dish antenna are used. They are parabolic in

shape. A dish antenna collects the signal coming from the Satellite & focuses it at a

point known as Focal point. Dish antenna is used to obtain VHF & UHF signals.

For different frequency ranges different sizes of dish antenna are used. The size of

dish antenna depends on wave length of the signal. For UHF range the size of the

dish antenna is 3 to 5 m & for signal up to 12 GHz the size is 91 to 180 cm. These

are made of fiber glass. The reflector at the dish antenna is made up of aluminum

or fiber glass. For different frequency the depth of the dish antenna is also

different.

Feed Horn:

A dish antenna receives the signal coming through a very large area, these get

reflected to a point, at that point a pipe type instrument is fitted. This pipe type

instrument is known as Feed Horn. From the feed horn the signals are given to

LNB. It is made in such a way that it can receive maximum signal on adjustment.

It is adjusted on the basis of picture & sound quality reception. It acts as

impedance matching amplifier.

Low Noise Block (Down Converter):

Most important part mounted on the disk antenna is LNB. The signal from the feed

horn is fed to LNB. These are of SHF range & contain unwanted frequencies. This

high frequency cannot be fed directly to TV. Theoretically LNB converts high

frequency range to low frequency range & also removes noise. In Satellite

reception different LNB are used for different frequency ranges. There is a high


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frequency amplifier in LNB to amplify the faded signals coming from the Satellite.

Now this signal is converted into low frequency of definite amount. There is a high

frequency local oscillator & mixer inside a LNB. The amplified signal from the

amplifier and the signal from the local oscillator come to the mixer sections just

like that in the normal tuner. The LNB used for C band reception gets the input of

3.7 to 4.2 GHz & the output is 950 to 1450 MHz. The output signals are then fed to

Satellite receiver through coaxial cables.

Satellite Receiver:

The purpose of Satellite receiver is the selection of channel for listening, viewing,

or both and transforming the signals in to a form suitable for input to domestic TV

and stereo equipment. Various subsections of Satellite Receiver.

1. Power supply

2. Down conversion and tuner circuit

3. Final IF stage

4. FM video demodulator

5. Video Processing Stages

6. Audio processing stages

Effective isotropic radiated power (EIRP) and foot print maps it the calculation of

the power received by an earth station from a Satellite transmitters fundamental to

the understanding of Satellite communications. Consider a transmitting source, in

free space, radiating a total power Pt, Watts uniformly in all directions called an

isotropic source. At a distance R from the hypothetical isotropic source, the flux

density crossing the surface of a sphere, radius R, is given by

F = Pt/RWatts/m2

In practice we use directive antennas to constrain out transmitted power to be

radiated primarily in one direction. The antenna has a gain G (6) in a direction 6,


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defined as the ratio of power per unit solid angle radiated in a given direction to the

average power radiated per unit solid angle:

G () = P ()/ (P0/4)

Where

P () is the power radiated per unit solid angle by the test antenna

G () is the gain of the antenna at an angle

The reference for the angle is usually taken to be the direction in which maximum

power is radiated, often called the boresight of the antenna. Thus for a transmitter

with output Pt Watts driving a lossless antenna with gain Gt, the flux density in the

direction of the antenna boresight at distance R meter is

F = Pt Gt/RWatts/m2

The product PtGt is often called the effective isotropically radiated power or EIRP,

and it describes the combination of transmitter and antenna in terms of an

equivalent isotropic source with power PtGt Watts, radiating uniformly in all

directions.

Footprint:

The geographic area towards which a Satellite down link antenna directs its signal.

The measure of strength of this footprint is the EIRP.

Downlink frequency allocations:

The ITU has split the world up into three regions. The approximate frequency

allocations above 10 GHz are as follows:

Region 1 : Europe, CIS, Africa and Middle East

Fixed satellite service (FSS) band 10.70 - 11.70 GHz

12.50 - 12.75 GHz

17.70 - 21.20 GHz

Direct broadcast service (DBS) 11.70 - 12.50 GHz


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Broadcast Satellite service (BSS) 11.70 - 12.50 GHz (from 2007)

Region 2 : The America, and Greenland


17.70 - 21.70 GHz


Broadcast Satellite service (BSS) 17.30 - 17.80 GHz (from 2007)

Region 3 : India, Asia, Australia and the pacific


17.70 - 21.20 GHz


Broadcast Satellite service (DBS) 21.40 - 22.00 GHz (from 2007)


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Experiment 2Objective:

Establishing a direct communication link between Uplink Transmitter and

Downlink Receiver using tone signal

Equipments Needed:

Uplink Transmitter

Dish Antennas

Downlink Receiver

Connecting cables

Procedure:

1. Connect the Satellite Uplink transmitter to AC Mains.

2. Switch ON the transmitter and frequency display will come on.

3. The transmitting frequency can be selected by frequency select switch. The

frequency can be changed from 2450-2468 MHz

4. Connect Antenna to Uplink transmitter with BNC -BNC lead.

5. Place Downlink Receiver at a convenient distance of 5 - 7m. (It can go even up

to 10m.).

6. Connect the Downlink Receiver to the AC Mains and switch it ON by mains

switch.

7. The Downlink Receiver Frequency can also be changed from 2414-2432 MHz

8. Attach Antenna to the Downlink receiver with BNC - BNC lead.

9. Align both the Transmitter and Receiver Antenna's in line.

10. Keep the Uplink transmitter and Downlink receiver frequency to the same

frequency.

11. Now Select the Tone from Channel Select B, so as to transmit tone signal

from Uplink transmitter.


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12. The Tone signal is switched to Audio II of transmitter and transmitted.

13. Make the Downlink Receiver in Speaker mode with the help of Channel

Select B

14. To observe Tone Signal on CRO select Tone mode from the Channel Select

B.

15. Connect CRO probes to received tone socket.

16. By changing the frequency and amplitude observe the received tone on CRO as

well as on speaker.

Note:This is a test link for direct communication between transmitter and

receiver.

Result:

A clear music indicates that the microwave link has been successfully setup

between uplink transmitter and down link receiver directly.


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Setting up an Active satellite link and demonstrate Link Fail operations.

Equipments Needed:

Uplink Transmitter

Dish Antennas

Downlink Receiver

Connecting cables.

Satellite Transponder

Theory:

The Uplink Transmitter sends signals at an Uplink frequency, which is higher than

downlink frequency to avoid the interference. The quality of signal is much

improved with active satellite especially when distances between transmitter and

receiver are considerable.

Procedure:



3. The transmitting frequency can be selected by Frequency Select switch. The

frequency can be changed from 2450-2468 MHz.


5. Place Downlink Receiver at a convenient distance of 5-7m. (It can go even up to

10m.).6. Place a Satellite Transponder between Transmitter and Receiver at a convenient

distance; preferably all three can be placed in equidistant triangle of distance 5-7m.

7. Connect the Satellite Transponder to the AC Mains and switch it ON by mains

switch.


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switch.

9. The Downlink Receiver Frequency can be changed from 2414-2432 MHz.



12. Adjust transmitter uplink frequency to 2468 MHz and Transponder receiver

frequency also to 2468 MHz, from frequency select 1 and frequency select 2.

Note: In actual satellite transponder the multiplexer and de-multiplexer are

provided which continuously keeps on receiving the input frequency's in the

satellite and transmit different 'output frequency. Here we do this proceduremanually to understand the operations of change in frequencies in the satellite. We

have two uplink frequencies and two downlink frequencies and we can

demonstrate manually how an actual satellite works.

13. Keep Downlink frequency of Transponder at 2414 MHz.

14. Keep the Downlink Receiver at 2414 MHz.

15. Now Select Tone from Channel select B in Uplink Transmitter.

16. Set the Downlink Receiver at speaker mode by changing Channel Select B.

Note:This is a test link for Active Satellite communication.

Link Fail Operation:

By switching Off the Power of Satellite Transponder, you can demonstrate a Link

Fail operation.

Result:

The above setup shows that a successful satellite communication link has been

setup between Transmitter and Receiver. The link failure operation can be

understood from the procedure.


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Establishing an Audio-Video satellite link between Transmitter and Receiver

Equipments Needed:

1) Uplink Transmitter

2) Dish Antennas

3) Downlink Receiver

4) Connecting cables

5) Satellite Transponder

6) Audio/ Video input (VCD)

7) Monitor (TV monitor)

Procedure:

1. Connect the Uplink Transmitter to the AC Mains and switch it ON by mains

switch.



3. Connect dish Antenna to Uplink transmitter with BNC -BNC lead.


10m.).

5. Place a Satellite Transponder between Transmitter and Receiver at a convenient


6. Connect the Satellite Transponder to the AC Mains and switch it On by mains

switch.


switch.



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9. Attach dish Antenna to the Downlink receiver with BNC - BNC lead.


11. Adjust transmitter uplink frequency to 2468 MHz and transponder receiver

frequency also to 2468 MHz.

12. Keep Downlink Frequency of Transponder to 2414 MHz.

13. Keep the Downlink Receiver to 2414 MHz.

14. Connect the Audio/Video signal at the input socket provided on the Uplink

Transmitter, Video at video input and audio at either Audio-I or Audio-II input.

15. To watch Video signal toggle the switch provided at Transponder unit to the

video position.

16. Connect TV monitor to the Audio/Video output of Downlink receiver. (Video

from Video Output, audio from Audio-I or Audio-II output (as in transmitter))

Set TV in AV Mode.

17. The TV monitor will display video and audio signal that you have connected to

Uplink Transmitter input.

18. Try link fail by using Transponder OFF.

Result:

The monitor display shows that a successful audio and video link has been

establish between Transmitter and Receiver through satellite.


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Experiment 5

Objective:

Communicating VOICE signal through satellite link

Equipments Needed:

1. Uplink. Transmitter

2. Dish Antennas

3. Downlink Receiver

4. Connecting cables.

5. Satellite Transponder

6. Microphone

Procedure:





4. Connect dish Antenna to Uplink transmitter with BNC -BNC lead.


10m.).




switch.8. Connect the Downlink. Receiver to the AC Mains and switch it ON by mains

switch.

9. The Downlink. Receiver Frequency can be changed from 2414-2432 MHz.

10. Attach dish Antenna to the Downlink receiver with BNC - BNC lead.


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frequency also to 2468MHz.

13. Keep Downlink Frequency of Transponder to 2414MHz.

14. Keep the Downlink Receiver to 2414MHz.

15. Connect microphone input at the socket marked 'MIC' on the Uplink

Transmitter.

16. Select MIC mode from Channel Select B in Uplink transmitter.

17. Select the Speaker mode from Channel Select B in Downlink Receiver.

18. Speak in the mike and you will hear the same sound in the speaker of receiver.

Result:

The above shows a successful establishment of voice link between transmitter and

receiver.


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Experiment 6

Objective:

Changing different combinations of uplink and downlink frequencies and to check

the communication link

Equipments Needed:

1. Uplink Transmitter

2. Dish Antennas




6. Audio/Video input (VCD)

7. Monitor (TV monitor)

Procedure:





4. Connect Dish Antenna to Uplink transmitter with BNC -BNC lead.


10m.).


distance; preferably all three can be placed in equidistant triangle of distance 5-7m.7. Connect the Satellite Transponder to the AC Mains and switch it ON by mains

switch.


switch.


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10. Attach Dish Antenna to the Downlink receiver with BNC - BNC lead.



frequency also to 2468 MHz



15. Connect the Audio/Video signal at the input socket provided on the Uplink

Transmitter, Video at video input and audio at either Audio-I or Audio-II input.

16. Connect TV monitor to the Audio/Video output of Downlink receiver. (Video

from Video Output, audio from Audio-I or Audio-II output (as in transmitter))

Set TV in AV Mode.

17. To watch Video signal toggle the switch provided at Transponder unit to the

Video position.

18. The TV monitor will display video and audio signal that you have connected to

uplink Transmitter input.

19. Now change uplink-transmitting frequency from 2468 to 2450 MHz and

correspondingly the receiver frequency of transponder is to be changed to 2450

MHz you will receive the same quality of signal at the output of the downlink

receiver.

20. Now change the downlink frequency of transponder from 2414 to 2432 MHz

and similarly change downlink receiver tuning frequency to 2432 MHz you will be

receiving the same quality of signal.

Result:

The above experiment shows a successful establishment of satellite audio/video

link between Uplink transmitter and Downlink receiver at different up-link and

down-link frequencies.


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Experiment 7

Objective:

Transmitting and receiving three separate signals (Audio, Video, Tone)

simultaneously through satellite link

Equipments Needed:

Uplink Transmitter

Dish Antennas

Downlink Receiver

Connecting cables


Procedure:

Connect the Satellite Uplink transmitter to AC Mains.

Switch ON the transmitterand frequency display will come on.

The transmitting frequency can be selected by Frequency Select switch. The


Connect Dish Antenna to Uplink transmitter with BNC -BNC lead.

Place Downlink Receiver at a convenient distance of 5-7m. (It can go even up to

10 m.).

Place a Satellite Transponder between Transmitter and Receiver at a convenient


Connect the Satellite Transponder to the AC Mains and switch it ON by mains

switch.

Connect the Downlink Receiver to the AC Mains and switch it ON by mains

switch.

The Downlink Receiver Frequency can be changed from 2414-2432 MHz.


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Attach Dish Antenna to the Downlink receiver with BNC - BNC lead.

Align both the Transmitter and Receiver Antenna's in line.

Adjust transmitter uplink frequency to 2468 MHz and transponder receiver


Keep Downlink Frequency of Transponder to 2414 MHz.

Keep the Downlink Receiver to 2414 MHz.

Connect the Audio/Video signal at the input socket provided on the Uplink

Transmitter, Video at video input and audio at Audio-I input.

Now Select the Tone from Channel Select B, so as to transmit tone signal


Connect TV monitor to the Audio/Video output of Downlink receiver. (Video

from Video Output, audio from Audio I output) Set TV in AV Mode. Keep

Downlink receiver voice switch in the On position.

To watch Video signal toggle the switch provided at Transponder unit to the

Video position.

The TV monitor will display video and audio signal that you have connected to

Uplink Transmitter input.

Make the Downlink Receiver in Speaker mode with the help of Channel

Select B. You will be able to hear tone in the speaker of receiver.

Result:

Three separate signals (Audio, Video and Tone) are successfully received at

downlink receiver through satellite communication link.


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Experiment 8

Objective:

Transmitting and receiving function generator waveforms through satellite link

Equipments Needed:


2. Dish Antennas




6. Function generator

Procedure:





4. Connect Antenna to Uplink transmitter with BNC-BNC lead.


10m.).




switch.8. Connect the Downlink Receiver to the AC Mains and switch it ON by mains

switch.



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10. The Downlink receiver On-Off toggle switch will switch On-Off the

receiver.




frequency also to 2468MHz.

14. Keep Downlink Frequency of Transponder to 2414MHz.

15. Keep the Downlink Receiver to 2414MHz.

16. Connect function generator Triangular wave output to Audio-I socket provided

on uplink transmitter.

17. Connect Audio-I socket of downlink receiver to the Oscilloscope.

18. Feed the signal of 1 KHz Triangular wave and you will observe similar wave

of same frequency on Oscilloscope.

Result:

Function generator waveforms are successfully received at downlink receiver

through satellite communication link.


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Experiment 9

Objective:

Transmitting and receiving PC data through satellite link

Equipments Needed:

Uplink Transmitter

Dish Antennas

Downlink Receiver

Software


USB cables -2 Nos.

Preferably 2 sets of PC's

Procedure:


2. Switch ON the transmitter by Mains switch and frequency display will light

up.





10m.).




switch.


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switch.



11. Align both the Transmitter and Receiver Antenna's in line such that both are in

parallel alignment.

12. Connect the Satellite Transponder to the AC Mains and switch it ON by

mains switch.





16. Switch ON the PC's and install software.

17. Connect interfacing cable from USB port of uplink transmitter to first PC.

18. Connect the interfacing cable from USB port of Downlink receiver to 2nd PC.

19. Install the drivers so that USB device is detected.

20. Now Select appropriate communication port and Baud Rate (19200) on both

PC's.

21. To watch PC Data toggle the switch provided at Transponder unit to the Video

position.

22. Select 1st PC as transmitter and 2nd PC as a receiver on the software window.

23. When the link is established, the typed matter on first PC will be received to

second PC via Satellite link.

Result:

PC data transmitted from first PC is received in the second PC via Satellite link.


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Experiment 10

Objective:

Study the delay between Uplink transmitter and Downlink receiver during data

transmission.

Equipments Needed:


2. Dish Antennas



5. Digital Storage Oscilloscope


Procedure:



up.





10m.).

6. Place a Satellite Transponder between Transmitter and Receiver at a convenientdistance; preferably all three can be placed in equidistant triangle of distance 5-7m.


switch.



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switch.




parallel alignment.





15. Select Data mode in the uplink transmitter using Channel Select A.

16. Select Data mode in the downlink receiver using Channel select A.

17. To observe data from data generator, toggle the switch provided at

Transponder unit to the Telemetry position.

18. Connect the DSO to Received Data section and observe the data.

19. The recommended DSO settings are as follows:

Adjust the Time/Div knob at 50ms.

Adjust Volt/Div. Knob at 2V.

Set appropriate trigger level, so that the signal becomes stable on screen.

20. Now slightly move the Delay Adjust knob and observe the changes in the Data

stream on DSO.

Result:

The experiment can be useful to observe simulated delay in satellite.


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Experiment 11

Objective:

To send tele-command and receive intensity of light from satellite

Equipments Needed:


2. Dish Antennas



5. Connecting cables

Procedure:

Connect the Satellite Uplink transmitter to AC Mains.

Switch ON the transmitter by Mains switch and frequency display will light

up.

The transmitting frequency can be selected by Frequency Select switch. The


Connect Antenna to Uplink transmitter with BNC -BNC lead.

Place Downlink Receiver at a convenient distance of 5-7m. (It can go even up to

10m.).

Place a Satellite Transponder between Transmitter and Receiver at a convenient


Connect the Satellite Transponder to the AC Mains and switch it ON by mains

switch.

Connect the Downlink Receiver to the AC Mains and switch it ON by mains


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switch.

The Downlink Receiver Frequency can be changed from 2414-2432 MHz.

Attach Antenna to the Downlink receiver with BNC - BNC lead.

Align both the Transmitter and Receiver Antenna's in line such that both are in

parallel alignment.

Adjust transmitter uplink frequency to 2468 MHz and transponder receiver


Keep Downlink Frequency of Transponder to 2414 MHz.

Keep the Downlink Receiver to 2414 MHz.

Select Tele mode in uplink transmitter and downlink receiver using Channel

select A.

The telemetry section has three toggle switches indicated E for enable, A1&A0

for selecting Light intensity and Temperature respectively. The command for light

intensity is 6.

In uplink Transmitter switch on the toggle E so that telemetry becomes

enable.

Now toggle On A1 and toggle Off A0 for Light Intensity and do same

setup

for downlink receiver.

To watch telemetry signal toggle the switch provided at Transponder unit to

the Telemetry position.

You will find that the intensity of light in percentage form is appearing on the

LCD screen of downlink receiver.

Change the intensity of light manually by using any light source on

transponder, the same ratio of percentage will appear on the LCD screen.

Result:


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As you send tele-command for light intensity, the transponder starts sending status

of light intensity to the receiver.

Experiment 12

Objective:

To send tele-command and receive Temperature from satellite

Equipments Needed:


2. Dish Antennas



5. Connecting cables

Procedure:



up.





10m.).


distance; preferably all three can be placed in equidistant triangle of distance 5-7m.7. Connect the Satellite Transponder to the AC Mains and switch it ON by mains

switch.


switch.


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parallel alignment.





15. Select Tele mode in uplink transmitter and downlink receiver using Channel

select A.

16. The telemetry section has three toggle switches indicated E for enable, A1 &

A0 for selecting Light intensity and Temperature respectively.

17. In uplink Transmitter switch on the toggle E so that telemetry becomes

enable.

18. Now toggle On A0 and toggle Off A1 for Temperature and do same set-up

for downlink receiver. The tele command for temperature is 5.

19. To watch telemetry data toggle the switch provided at Transponder unit to

the Telemetry position.

20. You will find that the Temperature of transponder is appearing on the LCD

screen of receiver.

Result:

As you send tele-command for temperature, the transponder starts sending status of

temperature to the receiver.


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Experiment 13

Objective:

To calculate the carrier to noise ratio of established satellite link

Equipments Needed:


2. Dish Antennas



5. CRO Connecting cables

Procedure:



up.





10m.).

6. Place a Satellite Transponder between Transmitter and Receiver at a convenientdistance; preferably all three can be placed in equidistant triangle of distance 5-7m.


switch.


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switch.




parallel alignment.





15. Disable Tone mode for transmission. In this case only carrier will get

transmitted from uplink transmitter.

16. Observe the Carrier waveform on Spectrum Analyzer and measure its power (It

is power of Carrier and Noise without any input, say it C1).

17. Now switch OFF the uplink transmitter and measure the power again (It is

power of Noise, say it N).

18. Now subtract amplitude of noise from previously received signal (Carrier +

noise), you can get actual Carrier signal amplitude (say it C). C = C1N

19. Calculate Carrier to noise ratio from the formula.

Carrier to noise ratio = C /N

Carrier to noise ratio (in dB) = 20 log C / N

Result:

Signal to noise ratio (in numeric) =_____

Signal to noise ratio (in dB) =_____dB


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Experiment 14

Objective:

To calculate signal to noise ratio of established satellite link

Equipments Needed:


2. Dish Antennas



5. CRO Connecting cables.

Procedure:



up.




5. Place Downlink Receiver at a convenient distance of 5-7m. (It can go even up to10m.).


distance; preferably all three can be placed in equidistant triangle of distance 5-

7m.


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switch.


switch.



11. Align both the Transmitter and Receiver Antenna's in line, such that both are in

parallel alignment.





15. Now Select the Tone from Channel Select B, so as to transmit tone signal


16. Make the Downlink Receiver in Tone mode with the help of Channel Select

B.

17. Observe Tone Signal on CRO and measure its amplitude. (The received tone

has original signal and noise both, say it S1 ).

18. Now change Tone mode to any other mode with the help of Channel Select

B of the uplink transmitter and again measure amplitude of received signal at

downlink receiver (This signal have only noise, say it N).

19. Now subtract amplitude of noise from previously received signal (Tone +

noise), you can get actual tone signal amplitude (say it S).

S = S1N

20. Calculate signal to noise ratio from the formula.

Signal to noise ratio = S / N

Signal to noise ratio (in dB) = 20 log S / N


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Result:

Signal to noise ratio (in numeric) =_____

Signal to noise ratio (in dB) =_____dB

Documents

Satellite Manual