Re: [Discuss-gnuradio] OFDM Transmiter and receiver by using USRP1

[waqasme]

Hello Marcus thanks for your reply.. Well the problem is there is not much
documentation available on internet on usurp .. Also I am quite new to gnu
radio and usrp1 ... I tried to play with interpolation and decimation
settings but didnot get the desired ofdm signal .. I am not sure what else I
can do to fix this problem . If u know any documentation regarding that
please do let me know . U mentioned about UHd but I could not find any UHd
blocks in gnu radio .. As I saw in one example someone use UHd .. Iam using
Ubuntu 10.10 and gnu radio companion 3.2.2 version .. I will really
appreciate if u can guide me how to setup the settings or specs i need for
usrp 1 .. Thanks and regards...

Marcus D. Leech wrote:
> 
>>
>> hi Marcus,
>>
>> I am attaching the screen shots and also block diagram of transmitter..
>> right now i am just trying to look for transmission of OFDM signal via
>> usrp1. As i mentioned earlier in the fft scope plot in gnu radio i see
>> the
>> typical ofdm signal but on the other hand in usrp sink on the spectrum
>> analyser i saw only simple sine wave peak. please have a look and let me
>> know if there is something else do i need to do to generate the proper
>> ofdm
>> signal on the spectrum analyser.
>>
>> /home/hp/Desktop/spectrumoutput.jpeg 
>> http://old.nabble.com/file/p32675018/spectrumoutput.jpeg
>> spectrumoutput.jpeg 
>>
>>
>>
>> Block diagram in GNU radio
>> /home/hp/Documents/finaltesting.grc 
>> http://old.nabble.com/file/p32675018/finaltesting.grc finaltesting.grc 
>>   
> Your flow-graph appears to be badly confused about bandwidths and
> interpolations and sample rates
>   --an interpolation ratio on your USRP1 sink of 100e6 is almost
> certainly *not* what you had in mind.
> 
> You probably need to learn more about all of that, and get some better
> notions of how the OFDM
>   modulator block works.  At the very least you'll need to
> fractionally-interpolate the baseband
>   up to some sample rather that *can* reasonably be further interpolated
> by the USRP1 hardware.
> 
> Given how simple this graph currently is, I'd *strongly* suggest that
> you upgrade your "world" to UHD,
>   since your investment in the "old world" is still rather small.
> 
> 
>>
>>   
> -- 
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
> 
> 
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> 

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