Evaluate the performance of the four-phase demodulator

Question

Solve the following problem:

Recall that MSK can be represented as a four-phase offset PSK modulation having the lowpass equivalent form

and {I_k} and {J_k } are sequences of information symbols (±1).

1. Sketch the block diagram of an MSK demodulator for offset QPSK.

2. Evaluate the performance of the four-phase demodulator for AWGN if no account is taken of the memory in the modulation.

3. Compare the performance obtained in part 2 with that for Viterbi decoding of the MSK signal.

4. The MSK signal is also equivalent to binary FSK. Determine the performance of noncoherent detection of the MSK signal. Compare your result with parts 2 and 3.