Re: [Discuss-gnuradio] problems with benchmark_ofdm and N210

[Morgan Redfield]

On Wed, Jun 8, 2011 at 7:20 PM, Marcus D. Leech <address@hidden> wrote:
> On 06/08/2011 09:51 PM, Morgan Redfield wrote:
>>
>> Ok. I found another problem in my code. The transmit_path has a
>> multiplier in it that was set to 200 (it could go up to 32768). This
>> was for the original USRP, but I think UHD needs a signal with
>> magnitude<=1. It seems like the signal was probably clipping. I
>> changed the magnitude of the multiplier and fiddled with the gain
>> parameters a bit. I'm now able to get the standard boxcar that I
>> expect for OFDM. There's still a spike at the center frequency though,
>> I don't see a gap.
>>
>> Thanks,
>> Morgan
>
> If you're doing these tests over-the-air, is it possible that there's a
> signal on TV channel 44 around you?
>  Channel 44 starts at 650MHz.
>
>
>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
>
>
>
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>

When I'm not transmitting, I don't really see anything above the noise
at the center frequency of 650MHz. There is a small spike (a few dB or
so) right at the center frequency, but I think that's due to the USRP.
Other messages on this list seem to indicate that it isn't abnormal.

That spike is only very noticeable when I'm transmitting. I'll try
changing the tx frequency and playing around with the gain tomorrow
and let you know how that goes.

Thanks,
Morgan