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Analysis of TDMA satellite transmission system

This question uses part of the FDMA question that has also been assigned (#434455).

The earth station in Question #1 transmits a digital data signal with a bit rate of 10 Mbps into a TDMA frame in a second transponder on the same GEO satellite. The transponder has a bandwidth of 36 MHz. The earth station modulation is QPSK and the transmitter has a bandpass RRC filter with filter rolloff = 0.2. The bandwidth occupied by the signal is the full 36 MHz of the transponder. The saturated power output of the second satellite transponder is 80.0 W and the transponder is operated with 1.5 dB output back off. Four similar earth stations each transmit 10 Mbps QPSK signals to the TDMA frame of the satellite transponder. The TDMA frame has a duration of 10 ms.

a. What is the symbol rate of the earth station transmissions?
b. What is the bit rate of the earth station transmissions?
c. What is the duration of the burst transmission from each earth station?
d. How much time is there in the TDMA frame that is not used for data transmission?
e. Why is the transponder power reduced by 1.5 dB instead of the 3 dB value used in Question #1?
f. Each burst transmission from each earth station starts with a 176 bit sequence called CBTR. What is the purpose of CBTR?

Solution Preview

The earth station in Question #1 transmits a digital data signal with a bit rate of 10 Mbps into a TDMA frame in a second transponder on the same GEO satellite. The transponder has a bandwidth of 36 MHz. The earth station modulation is QPSK and the transmitter has a bandpass RRC filter with ...

Solution Summary

The earth station in Question #1 transmits a digital data signal with a bit rate of 10 Mbps into a TDMA frame in a second transponder on the same GEO satellite. The transponder has a bandwidth of 36 MHz. The earth station modulation is QPSK and the transmitter has a bandpass RRC filter with filter rolloff = 0.2. The bandwidth occupied by the signal is the full 36 MHz of the transponder. The saturated power output of the second satellite transponder is 80.0 W and the transponder is operated with 1.5 dB output back off. Four similar earth stations each transmit 10 Mbps QPSK signals to the TDMA frame of the satellite transponder. The TDMA frame has a duration of 10 ms.

a. What is the symbol rate of the earth station transmissions?
b. What is the bit rate of the earth station transmissions?
c. What is the duration of the burst transmission from each earth station?
d. How much time is there in the TDMA frame that is not used for data transmission?
e. Why is the transponder power reduced by 1.5 dB instead of the 3 dB value used in Question #1?
f. Each burst transmission from each earth station starts with a 176 bit sequence called CBTR. What is the purpose of CBTR?

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