1. Sketch in detail a complete functional block diagram of a coherent receiver for offset QPSK, including carrier recovery and data clock synchronization. Can this receiver be used for MSK?
2. Two different methods are proposed for handling phase in a sixteen-ary orthogonal communication system. One method uses a noncoherent demodulator. The other method uses a coherent demodulator, but for carrier recovery, the waveform consists of alternating segments, 75 milliseconds of data symbols, followed by 25 milliseconds of unmodulated carrier, with the same average power as the modulated carrier. The average data rate of the two methods is the same. Which method should be preferred at a symbol error rate of 10-5? Give a reason. Does the answer depend on error rate?