Re: [Discuss-gnuradio] OFDM problem with USRP and GRC

[killol]

Hello all
I am also trying to get OFDM mod and demod blocks already present in
gnuradio distribution to work.
The blocks work when used on the same computer. Once I try to receive on the
other USRP, the OFDM demodulator does not demodulate any signal. 
Can anyone please let me know what problem might be there.

Someone suggested that there might be synchronaztion problem because of
which the receiver frequency drifts and does not demodulate the transmitted
frequency. 

Can someone please help me regarding the same.

Best,
Killol



손성환 wrote:
> 
> Hi all
> 
>  
> 
> I am trying OFDM transmission and receive test.
> 
> I’m using Ubuntu 9.10, gnuradio version 3.3 and two USRP boards with basic
> TX and RX and I am using GRC.
> 
>  
> 
> In the GRC I make simple test signal flow with usrp
> 
>  
> 
> Tx : File source -> OFDM mod -> USRP sink
> 
> Rx : USRP source-> OFDM demod ->file sink
> 
>  
> 
> As a my test I could not show not only constellation but also any other
> signal(scope and file data)
> 
> But I could show receive spectrum using fftsink with USRP
> 
> However I created simple example like follow, it operate well.
> 
>  
> 
> File source-> OFDM mod-> OFDM demod ->file sink
> 
>  
> 
> In order to test USRP part I tested gpsk example in the gnuradio-examples
> 
> It operate well. I could show constellation.
> 
>  
> 
> How can I operate well OFDMmod / demod examples?
> 
>  
> 
> Additionally I wanna confirm constellation of OFDM demod data.
> 
>  
> 
> But GRC block of the OFDM demod are encapsulate. So To confirm OFDM démod
> constellation, I guess that I sholul split OFDM démod block.
> 
> Am I correct?
> 
>  
> 
> Can you have a some hint?
> 
>  
> 
> Sohn
> 
>  
> 
> 
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> 
> 

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