Re: [Discuss-gnuradio] LFTX Rev 2.2 Compatibility Issue with USRP2

[juancolon]

Hi Josh,

Definitely both daughterboards has different frequency ranges, I just wanted
to test the TX channel of the USRP2 to make sure is working. 

That is the way I'm testing the LFTX, I have a spectrum analyzer connected
to the RX ports.

This is the flowgraph:
SignaSource ---> UHD:USRPSink

I have tested the USRP2 with previous UHD and also with the legacy gnuradio
version, but did not work either. LFTX pins are OK, and it works in the
N210, so probably something with the USRP2 motherboard. 

Thanks for suggestions,

Juan


Josh Blum-3 wrote:
> 
> 
> 
> On 06/20/2012 05:08 PM, juancolon wrote:
>> 
>> Hi,
>> 
>> We have a USRP2 with a LFTX Rev 2.2 daughterboard. When I run a GRC
>> program,
>> I try to look at the signal with a spectrum analyzer and the signal is
>> not
>> there. There is no error at all, everything seems to be up and running.
>> The
>> system is recognizing the USRP2, daughterboard and I have also played
>> around
>> with the subdev's but everything is correct.
>> 
>> To make sure there is nothing wrong with the LFTX, I pulled it out from
>> the
>> USRP2 and installed it on a USRP N210. In the N210 I re-run the same
>> exact
>> GRC program and finally see the signal at the spectrum analyzer. To
>> confirm
>> that the USRP2 transmit side is working, I've installed a RFX1800 and
>> re-run
>> the same GRC program and this also works perfect. 
>> 
> 
> LFTX and RFX1800 have very different frequency ranges. Perhaps you are
> not looking in the right frequency range for your signal? LFTX is just a
> direct line from the DAC, so +/- 30 or so MHz centered about DC.
> 
> I suggest putting a known signal into the usrp sink and put a scope on
> the output of the LFTX. If RFX is working, the DAC output should
> definitely be there.
> 
> -josh
> 
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> 

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