T1 carrier over GEO satellite link, CNR and BER
A T1 data transmission system transmits data at 1.544 Mbps over a GEO satellite link. At the receiving terminal the clear air value of overall (CNR)o is 19.0 dB. The modulation used on the link is QPSK and the implementation margin of the QPSK demodulator is 0.5 dB.
a. Find the BER at the receiver output and the average time between errors.
b. Rain affects the downlink from the satellite and the overall CNR ratio in the receiver falls by 6.0 dB to 13.0 dB. What is the bit error rate and the time between errors now?
c.If the modulation were changed to BPSK and the bit rate reduced by a factor of two when CNR overall is 13.0 dB, what BER would you expect from the link?