search

jgaeddert / liquid-dsp

digital signal processing library for software-defined radios
http://liquidsdr.org
MIT License
1.9k stars 443 forks source link

Liquid DSP - CPFSK #330

Closed JasleenKaur2308 closed 1 year ago

JasleenKaur2308 commented 1 year ago

What is the procedure for symbol synchronization in case of CPFSK demodulation ? link - https://github.com/jgaeddert/liquid-dsp/blob/master/examples/cpfskmodem_example.c

jgaeddert commented 1 year ago

As with a lot of things in digital communications, synchronization depends on the specifics of the waveform.

Is the transmission a burst? If so, then try to correlate against a known preamble. If not, and the signal is continuous (e.g. on for a very long duration), then you'll need a tracking loop similar to the symbol synchronizer, but for CPFSK. This would recover both timing and carrier phase information.

Of course the implementation would be heavily dependent upon the modulation index, pulse shaping filter, and other parameters. The dimensionality for this is pretty large, so there is no "one size fits all" solution which is why there isn't an easy implementation in liquid for this.