[USRP-users] Not getting white noise in a USRP N210

Marcus Müller marcus.mueller at ettus.com
Thu Sep 4 16:33:12 EDT 2014


About the pictures: Would you mind uploading them somewhere else? It
really takes ages for me to see a single one, and it blocks parallely
waiting for multiples, so I must admit I only saw the first two before I
gave up. Maybe imgur.com?

Greetings,
Marcus
On 04.09.2014 22:12, Ian Buckley via USRP-users wrote:
> Good point, I answered that very quickly without looking at the downloads. Do you understand Marcus's point about direct conversion architectures? It was perhaps more appropriate.
>
>
>
> On Sep 4, 2014, at 1:04 PM, Harold Daniel Moreno Urbina <haroldmk at gmail.com> wrote:
>
>> But neither 2.45 GHz nor 2.42 GHz are factor of 100 MHz. The other frequencies used are (1.8 GHz, 900 and 300 MHz).
>>
>>
>> 2014-09-04 13:53 GMT-06:00 Ian Buckley <ianb at ionconcepts.com>:
>> Very likely it's a harmonic of the 100MHz clock used extensively in the N210.
>> Try tuning to a frequency thats not a factor of 100MHz and see if it is still there.
>>
>> On Sep 4, 2014, at 12:24 PM, Harold Daniel Moreno Urbina via USRP-users <usrp-users at lists.ettus.com> wrote:
>>
>>> Hello, 
>>>
>>> When using USRP N210 without an antenna I would expect to receive white noise, right?. But consistently I am getting signal at center frequency well over 20 dB compared to other frequencies and 30 or dB over the signals near the edge.
>>>
>>> Anyone knows what is happening here? Is something wrong in the USRP or in GNU Radio? or me? Thanks.
>>>
>>>
>>> I am using USRP N210, GNU Radio 3.7.2.1 (version of last friday) over Ubuntu 14.04.
>>>
>>> I uploaded some screenshots of the FFT of the received signal, always 10Msps and getting about 5 minutes of signals. I used the example included in GNU Radio uhd_fft.grc and a custom flowgraph icluding only a USRP source and a FFT sink.
>>>
>>> ----------------------------------------------------
>>> uhd_fft.grc
>>> ----------------------------------------------------
>>>
>>> center frequency 2.45 GHz: https://mega.co.nz/#!WFE3UTRZ!AO04usGbl9TBa5-mCUPz7FYW2IabY5nbo5zZqSWwaM4
>>>
>>> center frequency 2.42 GHz: https://mega.co.nz/#!Hc0UzBJA!fSfgScdXPJ_phKdIWUKcNseonlKQt3m64yvYMR0bDhs
>>>
>>> ----------------------------------------------------
>>> Custom USPR2FFT
>>> ----------------------------------------------------
>>>
>>> center frequency 2.45 GHz: https://mega.co.nz/#!Hd9RyApS!FzsY5yxr5e6dJaAAO7Ww2O4BFefyCk6MDPN6ffcOs_g
>>>
>>> center frequency 1.80 GHz: https://mega.co.nz/#!LQcTkDjb!NQ7rIe1PDgRFCp547_U3mhxxxzsvQilPV-esTo7nHa4
>>>
>>> center frequency 900 MHz: https://mega.co.nz/#!eZ1TFbSY!nkt-n1mlC54aFfDwvqoJIJd7-a7gMB2GBLLhyclxxcs
>>>
>>> center frequency 300 MHz (out of SBX used operational band): https://mega.co.nz/#!mJ8EESwR!lI_0r4RvvTncxwwMnpEVAvrwsVhcHzLX7H6C7TA4Cj0
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>>
>
>
>
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