Re: [Discuss-gnuradio] How can Receiver separate between two different frequency's input

[Marcus D. Leech]

> I am working on an application where i receive input at audio_sink and 
> check for tone or data.
> Data is FSK modulated at 1k and 3k whereas Tone is of 2k (i.e Tone 
> lies in the middle).
>
> I have written a flow graph which consists of two heirarichal flow 
> graphs (tone_rx and data_rx).
> Input is received at audio_sink and then forwarded to both sub-graphs.
>
> My code works fine when tone is received but there is a problem when 
> Data is received.
> Because Data consists of FSK code and it has 2k components in it which 
> also triggers Tone graph.
>
> So i want to ask is there any GnuRadio Block by using which i can 
> avoid triggering of tone while receiving Data
> as i need to eliminate 2k component for Data but retain it when input 
> it is  Tone. OR
> is there any such method by which we identify at the start whether it 
> is data or tone.
> i am using laptop sound card (not usrp).
Simple first approximation.  Use the short-term-average power calculated 
over the data channels (1KHz and 3KHz), to drive a squelch
  function on the 2KHz channel.  I'll leave the details up to you, but 
I'd basically have some logic that said "if energy at 1KHz and energy at 
3KHz,
  squelch the 2KHz tone channel."




--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org