Q5) A bandpass communication system occupies a bandwidth of 20 MHz. It achieves a data rate of 10 Mbps and a BER = Q(3.5
Posted: Sun May 15, 2022 7:43 pm
Q5) A bandpass communication system occupies a bandwidth of 20 MHz. It achieves a data rate of 10 Mbps and a BER = Q(3.5) using BPSK with amplitude levels – 1 and +1. To increase the data rate the modulation method is changed to 4-ary ASK with amplitude levels – 3a, –a, +a and +3a. The baseband pulse shape, the bandwidth of the transmitted signal and channel noise power all remain unchanged. For the 4-ary ASK system, find the value of a that will yield a BER = 0.75 x Q(3.5). [4 marks] Hint: • For BPSK: BER = Q(V2Eb/N.). Eь • For 4-ary ASK: Eb = 1.25a-T and BER = 0.75 Q 1.25N. = = 3