Re: [Discuss-gnuradio] Setting up clock synchronization blocks

[Martin Braun (CEL)]

On Thu, Feb 21, 2013 at 02:10:24PM +0100, Nemanja Savic wrote:
> Preamble is indeed long. On the figure I attached in my first post it can be
> seen the input and output od
> synchronization M&M block. I am expecting this block to do synchronization
> based on preamble.

Your packet sync, but not your clock sync (how would the M&M even know
about your preamble?).

> Not quite sure that I understand, but I am sampling signal with ca. 500k, and
> symbol rate is 19.2k, so if you were thinking about oversampling after bit
> slicer, yes i have oversampling of ca. 25.

Yeah, that's probably over the top. Filter and decimate, that saves
clock cycles and possibly improves your SNR.

> In my receiver, after a bit filtered demodulated signal from quadrature FM
> demodulator, I have a block, designed by myself, that does bit slicing. It is
> basically simulation of a circuit that is used in
> 
> some receivers with min and max diode detector circuits. Since I am quite sure
> this is not the usual way of doing this, how am I supposed to get digital
> pulses from demodulated signal.

I recommend parsing gr-digital/python/gmsk.py for an idea how this could
be done (though, granted, that doesn't work perfect either, but also
doesn't sync via preamble).

MB

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