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CPFSK demodulation and synchronization

Started by gobruins December 2, 2010

Darol wrote:

> On Dec 2, 1:54 pm, Vladimir Vassilevsky <nos...@nowhere.com> wrote: > >>>One non-coherent approach is to use a differential detector followed >>>by a decision feedback equalizer (DFE). The output from the >>>differential detector could be sampled at twice the baud rate before >>>being fed to the DFE, and the phase of of the sampling doesn't have to >>>be controlled because the DFE will adapt. >> >>He uses RECTANGULAR pulses. What is the point of DFE ? > > Even with rectangular modulating pulses, isn't a DFE beneficial > because of the memory required to implement CPFSK?
That memory is already taken into account by the differential detector.
>>>This method may not be generic enough for you because it works best >>>with signals that contain a preamble. >> >>Any method works with or without preamble. Preamble is a small matter of >>convenience, no more then that. > > With a preamble, cannot the DFE train faster and with greater accuracy > than using a blind technique (e.g. constant modulus)? This would lower > BER, especially for bursty signals.
By preamble, I meant a regular sequence for carrier and sync acquisition. Unless for some special cases, equalizer can't train on the regular sequence. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com