dbpsk调制解调程序

SYMPCHUNK sets the number of symbols demodulated at once with a constant carrier frequency and symbol timing offset. This is a fundamental decoder parameter that establishes its carrier and symbol timing tracking bandwidth. Set it too low and the demodulator can"t accurately determine carrier frequency and symbol timing on a noisy signal. Set it too high and the demodulator may not be able to track large symbol rate offsets caused by Doppler shift and/or A/D or spacecraft clock errors. Or it might have trouble tracking high rates of change in the carrier frequency due to Doppler acceleration.The current value of SYMPCHUNK is 4*N1 = 512, where N1 = 128 is the order of the convolutional interleaver. 512 symbols is 512 milliseconds at 1000 symbols/sec, giving a frequency/time determination SNR that is 10*log10(512) = 27 dB greater than the Es/N0, not counti