Islamic University of LebanonFaculty of EngineeringCCE Department

Training Report

Title:

Satellite Communication

Realise par:

Ahmad Hallak

2013-2014

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THANKS

I thank OGERO organization and all people that help us to accomplish this training period with success.

I thank the head of CCE department Dr walid fahas and Dr jamal haydar for giving me this chance.

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ContentsTable of figures............................................................................................................................................6

Introduction.................................................................................................................................................7

Chapitre 1....................................................................................................................................................8

1.3 APPLICATIONS OF SATELLITES...........................................................................................................8

1.3.1) Weather Forecasting.................................................................................................................8

1.3.2) Radio and TV Broadcast.............................................................................................................8

1.3.3) Military Satellites.......................................................................................................................8

1.3.4) Navigation Satellites..................................................................................................................9

1.3.5) Global Telephone......................................................................................................................9

1.3.6) Connecting Remote Areas.......................................................................................................10

1.3.7) Global Mobile Communication................................................................................................10

chapitre 2.................................................................................................................................................12

Satellite communication systems(transmition).....................................................................................12

Modulator..........................................................................................................................................12

Associated equipment.......................................................................................................................12

Characteristics of Modulators............................................................................................................13

UP Converter.....................................................................................................................................13

Presentation......................................................................................................................................13

Characteristics...................................................................................................................................13

Line amplifier(LA)...............................................................................................................................14

The wave guide(wg)...........................................................................................................................14

Power amplifier (HPA).......................................................................................................................14

Type of Power Amplifiers...................................................................................................................14

Antenna.............................................................................................................................................14

Chapitre 3.................................................................................................................................................15

Satellite communication systems(receiving).........................................................................................15

Antennas...........................................................................................................................................15

Low noise amplifier (LNA)..................................................................................................................15

Line amplifier(LA)...............................................................................................................................16

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The wave guide(wg)...........................................................................................................................16

Down Converter................................................................................................................................16

Presentation......................................................................................................................................16

Characteristics...................................................................................................................................16

Demodulator.....................................................................................................................................17

Amplification.....................................................................................................................................17

Characteristics of Demodulator.........................................................................................................17

Chapitre 4.................................................................................................................................................18

IF Channel Selection..............................................................................................................................18

For transponder 20............................................................................................................................18

For transponder 8..............................................................................................................................19

For transponder 8..............................................................................................................................19

Demodulator’s channel.....................................................................................................................20

Channel numbers...............................................................................................................................20

Chapitre 5.................................................................................................................................................21

SIMULATION OF LINE-UP PROCEDURE..................................................................................................21

Required instruments and steps........................................................................................................21

Conclusion.................................................................................................................................................26

references.................................................................................................................................................27

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Table of figures Figure 1......................................................................................................................................................12Figure 2......................................................................................................................................................15Figure 3......................................................................................................................................................18Figure 4......................................................................................................................................................21Figure 5......................................................................................................................................................22Figure 6......................................................................................................................................................24

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Introduction The aim of this report was to focus on the main objectives and courses related to international telecommunications in Lebanon achieved in the 2013 summer training period in the training department at OGERO organization.The international telecommunications sector includes 1 main systemsSatellite communication systemOur training option was mainly focusing on the satellite communication systems. This training period was including:

Theoretical courses related to international telecommunications, satellite communications principles, satellite earth stations equipment and configuration, modems, antennas, power amplifiers, link budgets, fiber optic cables and more…Visits to international telecommunication sites: Arbanieh satellite earth station(telephony over satellite), Jouret el Ballout satellite earth station(TV broadcasting),.Practical simulation of line-up procedure at Arbanieh satellite earth station.This training period allows to us achieving a deeper view of digital communication systems over satellites and helps us to improve and to extend our knowledge in this field of telecommunications.

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Chapitre 1

1.3 APPLICATIONS OF SATELLITES

1.3.1) Weather Forecasting

Certain satellites are specifically designed to monitor the

climatic conditions of earth. They continuously monitor the assigned

areas of earth and predict the weather conditions of that region.

This is done by taking images of earth from the satellite. These

images are transferred using assigned radio frequency to the earth

station. (Earth Station: it‟s a radio station located on the earth and

used for relaying signals from satellites.) These satellites are

exceptionally useful in predicting disasters like hurricanes, and 4

monitor the changes in the Earth's vegetation, sea state, ocean

color, and ice fields.

1.3.2) Radio and TV Broadcast

These dedicated satellites are responsible for making 100s

of channels across the globe available for everyone. They are also

responsible for broadcasting live matches, news, world-wide radio

services. These satellites require a 30-40 cm sized dish to make

these channels available globally.

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1.3.3) Military Satellites

These satellites are often used for gathering intelligence, as

a communications satellite used for military purposes, or as a

military weapon. A satellite by itself is neither military nor civil. It is

the kind of payload it carries that enables one to arrive at a decision

regarding its military or civilian character.

1.3.4) Navigation Satellites

The system allows for precise localization world-wide, and

with some additional techniques, the precision is in the range of

some meters. Ships and aircraft rely on GPS as an addition to

traditional navigation systems. Many vehicles come with installed

GPS receivers. This system is also used, e.g., for fleet

management of trucks or for vehicle localization in case of theft.

1.3.5) Global Telephone

One of the first applications of satellites for communication

was the establishment of international telephone backbones.

Instead of using cables it was sometimes faster to launch a new

satellite. But, fiber optic cables are still replacing satellite

communication across long distance as in fiber optic cable, light is

used instead of radio frequency, hence making the communication

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much faster (and of course, reducing the delay caused due to the

amount of distance a signal needs to travel before reaching the

destination.).

Using satellites, to typically reach a distance approximately

10,000 kms away, the signal needs to travel almost 72,000 kms,

that is, sending data from ground to satellite and (mostly) from

satellite to another location on earth. This cause‟s substantial

amount of delay and this delay becomes more prominent for users

during voice calls.

1.3.6) Connecting Remote Areas

Due to their geographical location many places all over the

world do not have direct wired connection to the telephone network

or the internet (e.g., researchers on Antarctica) or because of the

current state of the infrastructure of a country. Here the satellite 5

provides a complete coverage and (generally) there is one satellite

always present across a horizon.

1.3.7) Global Mobile Communication

The basic purpose of satellites for mobile communication is

to extend the area of coverage. Cellular phone systems, such as

AMPS and GSM (and their successors) do not cover all parts of a

country. Areas that are not covered usually have low population

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where it is too expensive to install a base station. With the

integration of satellite communication, however, the mobile phone

can switch to satellites offering world-wide connectivity to a

customer. Satellites cover a certain area on the earth. This area is

termed as a „footprint‟ of that satellite. Within the footprint,

communication with that satellite is possible for mobile users.

These users communicate using a Mobile-User-Link (MUL). The

base-stations communicate with satellites using a Gateway-Link

(GWL). Sometimes it becomes necessary for satellite to create a

communication link between users belonging to two different

footprints. Here the satellites send signals to each other and this is

done using Inter-Satellite-Link (ISL)

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chapitre 2

Satellite communication systems(transmition)

Figure 1

Modulator Modulator to be used to modulate a variable data rate (64Kb/s to 2048 kb/s or E1) base band digital signal into IF (Intermediate Frequency) 140±36Mhz using QPSK. The base band interface G.703 to be connected from DDF (Digital Distribution Frame) interface, and the IF signal to be connected to the IF interface of the Up Converter.

The IF frequency is generated by a synthesizer with a 22.5 Khz increment. (Total of 3200 channels)

Associated equipment The modulator, equipped with transmit synthesizer is used in association with a ground interface board, demodulator and VITERBI decoder module, to constitute a digital transmission.

The modulator module comprises two main circuits:

1- IF signal processing circuit, generating an IF carrier in the 140+/- 36 Mhz

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1- Interface/digital processing circuit, generating P and Q streams for the IF part, from the “clock” and “Data” signals from the ground interface.

Characteristics of Modulators Modulation: QPSK Data Rate: (64 KB/S TO 2.048 MB/S or E1)IF Tuning: 140 MHZ ± 36MhzIF impedance: 75 ΩIF Connector BNCOutput Power: -20 TO +5.0 dBm IN 0.1 dB steps Output stability: ± 0.5 DB Over time and temp.Output Spectrum: Meets IESS 308 Power Spectral MaskFEC Encoding: VITERBI, K=7 AT 1/2, 3/4Outer Encoding: Reed-Solomon INTELSAT ratesData Clock Source: Internal, External & RX RecoveredTerrestrial Interface:G.703 E1, 120 Ω Balanced, HDB3

UP Converter Presentation This equipment is used to convert an IF signal (140MHz) into RF signal (5.85 – 6.425 GHz). Usually, the operator selects the center frequency of the transponder carrying the traffic.

The Up converter translates the IF band (140+36 MHz) in the SHF band (Fc+/36MHz); the selection of the carrier frequency is made with the modulator’s channel number.

The Up converter is designed for the use in the terrestrial stations of satellite telecommunications systems.

It has been developed to meet all the requirements of digital and analog transmission standards.

Characteristics Input frequency : 140 +/- 36MHz

Input level: -10 dBm to –50 dBm

Output frequency: 5.85 – 6.425 GHz

Steps: 125KHz

Frequency stability: +/- 3X10-8 /month

Output level: < -10 dBm

Gain: 0 dB

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Line amplifier(LA) We put a line amplifier to increase the gain of +19 Db

The wave guide(wg) The wave guide decrease the gain of -12.5Db

Power amplifier (HPA) The basic function of a power amplifier in an Earth station is to amplify the

low-level RF carrier(s) provided by the Up Converter to a higher power level

to ensure that a correct EIRP per carrier is radiated to the satellite.

Type of Power Amplifiers Common types of power amplifiers found in Earth Stations are the Klystron Power Amplifier (KPA), the Traveling Wave Tube Amplifier (TWTA), and the Solid State Power Amplifier (SSPA).

In recent times, SSPAs have gained place, especially where a medium or low power is required in applications, such as VSATs, low traffic stations, or old standard A antennas where the high-gain antenna (HGA) enables use of small amplifiers. With recent advances in solid state microwave power devices, phase combined SSPAs delivering up to 800W in C-band and 400 W in Ku-band, have become available.

The HPA increase the gain of +70 Db

Antenna The antenna transmit the RF signal over the satellite with a gain of 60 Db.

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Chapitre 3

Satellite communication systems(receiving)

Figure 2

Antennas The antenna on the reception receive the RF signal with a gain of +56.5 Db

Low noise amplifier (LNA) Low-noise amplifiers (LNAs), as the name suggests, are amplifiers that have a very good noise performance coupled with a wide bandwidth. This makes them essential for use as the first stage of a satellite ground station receiving chain.

The system Figure of Merit (G/T) for an Earth station is virtually determined by the Noise Figure (F) and gain of the LNA, along with the antenna gain.

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The LNA is generally mounted as close to the antenna feed as possible so that the transmission line losses to the LNA will be at an absolute minimum.

An LNA must also provide sufficient gain to overcome losses in the transmission line between the receiver and the LNA.

The LNA increase the gain of +60 Db

Line amplifier(LA) We put a line amplifier to increase the gain of +19 Db

The wave guide(wg) The wave guide decrease the gain of -12.5Db

Down Converter Presentation This equipment is used to convert an RF signal (3.625 –4.2 GHz) coming from the LNA into IF signal (140 MHz). Usually, the operator selects the center frequency of the transponder carrying the traffic.

The Down converter translates the SHF band (Fc + 36 MHz) into the receive IF band (140+36 MHz), the selection of the carrier frequency is made with the demodulator’s channel number.

The Down converter is designed for the use in the terrestrial stations of satellite telecommunications systems.

It has been developed to meet all the requirements of digital and analog transmission standards.

Characteristics Input frequency : 3.625 – 4.2 GHz

Steps: 125KHz

Frequency stability: +/- 3X10-8 /month

Input level: -35 dBm to –85 dBm

Output frequency: 140 +/- 36MHz

Max Output level: +10 dBm

Gain: 38 dB

Manual adjustment range: +/- 10 dB

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Demodulator Demodulator to be used to demodulate a QPSK IF (Intermediate Frequency) 140±36Mhz signal into a variable data rate (64Kb/s to 2048 kb/s) base band digital signal. The base band interface G.703 to be connected from DDF (Digital Distribution Frame) interface, and the IF signal to be connected to the IF interface of the Down Converter.

Amplification The RF signal can be received in a wideband (72 MHz for 140 MHz IF). The relevant carrier occupies a reduced part of this bandwidth.The automatic gain control (AGC) must compensate the differences both of the spectral density (coming from the uplink) and of the global level (due to the downlink). The variable rate of carried data involves a variation of spectrum bandwidth which increase the complexity of the gain control somewhat. An AGC is based on a bandpass filter, a variable gain amplifier, a detector and a feedback loop.

Characteristics of Demodulator Demodulation: QPSK Rate: 64 KB/S TO 2.048 MB/SIF Tuning: 140 MHz ± 36MHzIF Impedance: 75 ΩIF Connector BNCInput Level: -55 TO –25 dBmSpectrum: MEETS IESS 308 Descrambler: IDR DescramblingFEC: VITERBI, K=7 AT 1/2, 3/4, Decoding: Reed-Solomon INTELSAT RatesTerrestrial Interface:G.703 E1 (2.048 MB/S), 120 Ω

Balanced, HDB3

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Chapitre 4

IF Channel Selection We are going to establish a 2Mb/s channel between Lebanon (Arbanieh Satellite Earth Station) and Saudi Arabia (Jeddah Satellite Earth Station).

Arabsat company gives us the permission to use 6374.175 MHz as the Up link frequency on transponder 20, and 3872.9075 MHz as the down link frequency on transponder 8

When we select a transponder, we have to consider tow issues:

1- The center frequency of the transponder

2-The bandwidth

Arabsat Transponder, 2B satellite

Figure 3

For transponder 20 Center Frequency = 6364.5 MHz

Bandwidth= 36 MHz

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For transponder 8 Center Frequency = 3863.75 MHZ

Bandwidth = 36 MHz

IF calculation

RF Frequency: 6374.175 MHZ

Center Frequency of TXP 20 : 6364.5 MHz

Step 1:

Set the center frequency of the up converter on 6364.5 MHZ

Step 2:

Connect the RF output of the Up Converter to the RHCP

The center frequency of the Up converter corresponds of the center frequency of the modulator, in our case the 140 MHZ (Channel 1600) = 6364.5 MHz (fc)

We are looking to transmit on 6374.175 MHz (ft)

Δf = fc - ft

Δf = 6364.5 – 6374.175 = - 9.675 MHZ

ft is higher than fc by 9.675,

The IF = 140 + 9.675 = 149.675 MHZ

The TX channel become: (9675/22.5) = 430

1600 + 430 = 2030

For transponder 8 Center Frequency = 3863.75 MHZ

Bandwidth = 36 MHz

Setting the Down converter

Step 1:

Set the center frequency of the down converter on 3863.75 MHz

Step 2:

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Connect the input of the down converter to the appropriate polarization, in our case LHCP

Demodulator’s channel The center frequency of the Down converter corresponds the center frequency of the IF for the demodulator, which is 140 MHZ (Channel 1600) = 3863.75 MHz (fc)

We are looking to receive on 3872.9075 MHz (fr)

Δf = fc - fr

Δf = 3863.75 – 3872.9075 = -9.1575MHZ

fr is higher than fc by 9.1575 MHz,

The IF = 140 + 9.1575 = 149.1575HZ

The RX channel become: (9157.5/22.5) = 407

1600 + 407 = 2007

Channel numbers The IF channel of the modulator is: 2030

The IF channel of the Demodulator is: 2009

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Chapitre 5

SIMULATION OF LINE-UP PROCEDURE Required instruments and steps BER Test Set

IF Spectrum Analyzer

Test Loop Translator

IF Noise generator

IF Step Attenuator

IF Power Combiner

Step 1

Connect the test equipment (that is, the BER test set, the IDR channel unit, and the IF noise generator) as shown in the next Figure. The scrambler and FEC must be active.

Figure 4

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Step 2

Turn off the IF noise by either removing the output of the generator and terminating the power combiner input, or by setting the noise attenuator to maximum attenuation (attenuation must be high enough to ensure that the noise is more than 20 dB below the carrier).

Step 3

Adjust the carrier level attenuator to produce the nominal IF level at the input to the demodulator. The nominal level should be determined from the manufacturer's instructions for the unit. This level should be approximately the same as that expected in-service.

Step 4

Set the pattern mode switch of the BER test set to the appropriate pseudo-random bit pattern as given in Table 11.

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Figure 5

Step 5

Start the BER test set and verify that the test setup is working properly. No errors should be observed unless the BER transmitter is forced to inject errors. Force a few errors to confirm proper operation.

Step 6

Reconnect or turn on the IF noise source and decrease the noise attenuator setting (increase the noise level) until the channel unit loses synchronization (carrier or clock recovery slips or FEC decoder synchronization losses).

NOTE: The definition of synchronization loss is somewhat arbitrary. For the purpose of this test, a loss of synchronization occurs when the demodulator

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or decoder (not the BER test set) loses synchronization once every 30 seconds (or more frequently).

Step 7

Measure and record the (Co+No)/No, using the spectrum analyzer method. Ensure that the total power of carrier plus noise at the demodulator input does not exceed the demodulator input level limits recommended in the manufacturer's

instructions.

NOTE: When using the spectrum analyzer method, the settings recommended in Column B of Table 10 should be employed. The amplitude scale should be set to 2 dB per division.

Figure 6

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Step 8

Gradually increase the C/N by decreasing the noise power (increase the noise power adjustment attenuator setting) until the channel unit just regains synchronization. Measure and record the (Co+No)/No.

NOTE: The value of (Co+No)/No obtained in Step 8 will be somewhat higher than that obtained in Step 7.

A 0.1 dB step attenuator capability may be required.

Step 9

Increase the C/N by decreasing the noise level (increase the noise attenuator setting) by 0.5 dB. Measure and record the (Co+No)/No and any in-service readouts.

Step 10

Re-start the BER test set and measure the BER at this (Co+No)/No.

NOTE: At high BER, for example, for BER greater (worse) than 1E-5, the test should be run until at least a two (2) minute test interval has elapsed.

Step 11

Record the BER reading, the (Co+No)/No value and the channel unit in-service readout such as BER, Eb/No and IF level.

Step 12

Increase the (Co+No)/No by decreasing the noise power (increasing the noise level setting attenuator) by 1.0 dB.

Step 13

Measure and record the (Co+No)/No and the channel unit (modem) receiver in-service readout (Eb/No and/or receive IF level).

Step 14

Re-start the BER test set, and measure and record the BER at this (Co+No)/No. Refer to Notes 1 and 2 below for the recommended test interval.

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1. In order to ensure a valid BER reading at high BER, ex. BER greater (worse) than 1E-5, the test should be run until at least a two (2) minute test interval has elapsed.

2. At low BER, ex. BER lower (better) than 1E-5, the test should be run until at least 1,000 errors are recorded or until at least a one-hour test interval has elapsed, whichever occurs first.

Step 15

Repeat Steps 12, 13 and 14 until a BER better than 1E-8 or no errors are recorded in a one-hour test interval.

Conclusion This training has helped us a broader understanding of the connections through

system satellite

We identified on how to open a line between the two countries and have its

experience of this work has helped us in giving us experience in our lives

through the process dealt directly with the devices and how they work

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references Wikipedia

www.ssloral.com

www.satellites.spacesim.org

dr.george francis

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