Re: [Discuss-gnuradio] Frequency recovery of known signal

[Marcus Müller]

Hi Mohammad,

multiplying with a tone is, mathematically, a frequency shift! So,
maybe you'd want to multiply your input signal with your error
frequency?

You could also estimate the frequency of your tone (there's different
ways of doing that), and generate a complex tone (with the frequency
modulator) that you use to correct your input frequency.

Other than that: we do have PLL blocks, including a frequency detector,
in gr-analog!

Best regards,
Marcus

On Sat, 2017-11-18 at 19:49 +0330, mohammad nejati wrote:
> Hi ,
> I have a two known signal with some frequency offset between them
> , without time delay difference , i can conjugate-multiply two
> signals and get a tone proportional to offset value (pls find
> attached picture for flow-graph i used) .
> I think i need some sort of PLL and NCO to correct frequency offset
> and lock to known signal .
> As i know , it's impossible in gnu radio flow graph to make closed
> loop systems , but how i can implement that in one block ? are there
> any example block that implemented some thing like that ?
> 
> Thank you .
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