[USRP-users] X310 + 2 CBX daughtercards strange behaviour

Marcus D. Leech mleech at ripnet.com
Fri Sep 19 17:16:20 EDT 2014


> Hi Markus and Mike,
>
> Thank you for your answers.
>
> It does not change anything whether you specify the subdev or not.
>
> Markus: yes everything is wired properly. Concerning the last email, I 
> used a BladeRF as a generator (0dBm + 30dB attenuator).
>
> Here is another test with Wifi and as you can see from the two 
> spectrum scopes (upper is RF 1, lower RF 0), RF 1 reception bandwith 
> seems to be larger than for RF 0 (however it's set to 20MHz for both 
> channels).
>
> I have a second X310 with the same daugthercards and I get the same 
> behaviour...
>
> Is there a way to use just RF 1?
>
> I hope that going to sleep is going to help me to find an idea to 
> solve the problem :-)
>
> Best regards
>
> Hervé
>
The bandwidth setting doesn't do anything on the CBX card--it's only 
used to set the analog bandwidth between the cards baseband/IF output, and
   the ADC.

The bandwidth delivered to the host depends, in this case, on the 
specified sample rate.

What type of host interface are you using in this case?  From the 
spectrum plots, it looks like you're asking for two channels of 25Msps 
each, which
   will not "fit" over 1GiGe at 16-bit samples.

Do you get any 'O' being output while you run this flow-graph?  What 
type of computer?




-- 
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org





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