Re: [Discuss-gnuradio] Can threading disturb sensing continuety

[Brian Padalino]

On Fri, Mar 20, 2009 at 1:27 PM, Johnathan Corgan
<address@hidden> wrote:
> A common, non-coherent method for FSK demodulation and baud rate
> detection is to multiply each succeeding sample by the complex
> conjugate of the preceding sample, then take the phase of the product.
>  This turns the sample series into baseband "level" shifts.  If you
> are at zero IF, then the sample stream will be roughly symmetrical
> about zero (frequency offsets are turned into DC offsets, though).
> From here you can use zero crossings to estimate baud rate and
> integration between transitions to improve noise performance.  The
> success of this technique relies on sufficient zero crossing density,
> and has a higher bit error rate than coherent detection and
> demodulation.

Assuming an FSK system with unknown frequency separation and baudrate,
is the above algorithm robust enough to determine said parameters to
then pass along to a coherent demodulator to achieve a better BER?

I would assume yes - since you're just taking a quick guess/estimate
and letting the coherent demodulator actually timetrack, figure out
the bits, etc.

Brian