Re: [Discuss-gnuradio] OFDM MODULATION/DEMODULATION PROBLEM

[Josh Blum]

On 10/18/2012 04:47 AM, Bilal wrote:
> Hi
> I m using USRP2 and USRPN210 DB RFX900.
> 
> Block diagram
> MOD:random source-->ofdm-->usrp sink
> DeMOD:usrp source-->ofdm demod-->>sink scope,fft
> 
> Problem is that:
> Modulation is going fine,even at the receiver end the spectrum is just like
> it should be (block for OFDM )
> but there is nothing at the output of OFDM demod block Sink Scope is showing
> nothing. <http://gnuradio.4.n7.nabble.com/file/n38053/OFDM_DeMOD.png> 
> <http://gnuradio.4.n7.nabble.com/file/n38053/OFDM_Mod.png> 
> <http://gnuradio.4.n7.nabble.com/file/n38053/Spectrum.png> 
> I have attached the mod,demod,received spectrum snaps.
> Help is highly appreciated...:-) 
> 

1 few things:

1) Remove the throttles, the sample rate is already throttled by the
usrp. There will be a fight.

2) I see an exception printed in the GRC window for one of the
screenshots. That might be important to share?

3) The random source should probably be 0 to 1 << 32. I believe thats a
32 bit integer stream. Things might not work as expected when the input
bits are mostly 0.

-josh