> > OK next question... >> >> What else do you already know "a priori" about the QPSK signal? >> for example >> do you already know the symbol rate? >> do you already know what data pattern it on it? >> anything else? >> >> Mark > >The only information known is the carrier frequency is from 500MHz to700MHz, bit rate around 2Mbit/s, and it uses QPSK modulation.> >Thanks. >No. It is not possible at -20 dB. Raising the signal to the 4th power creates additional noise (noise x noise + signal x noise + signal x noise etc.). The threshold difference to recover the carrier frequency should increase by several dBs between training (known symbols) and modulation removal through 4th power. Read about the threshold problem in carrier recovery too. Basically, below a certain threshold, carrier recovery algorithms encounter a 'knee' yielding incorrect results. _____________________________ Posted through www.DSPRelated.com
Detection of weak QPSK signal, e.g., SNR=-20dB
Started by ●January 16, 2014
Reply by ●January 27, 20142014-01-27
