[USRP-users] X310, 2 channel sample time and phase alignment

Marcus D. Leech mleech at ripnet.com
Tue Sep 2 11:49:19 EDT 2014


On 09/02/2014 11:23 AM, Kemp, Elizabeth - 1008 - MITLL via USRP-users wrote:
>
> Hi,
>
> I have a test set up where I am recording on both channels of an 
> X310.  I have the output of a signal generator connected to the 
> channels through a splitter (and equal length cables).  I am using the 
> BasicRX Daughterboards (1-250 MHz).
>
> I have attached a screenshot from GRC of the WX GUI that shows a plot 
> of the real samples, and the magnitude of the two channels.  As you 
> can see in the magnitude plot, the two channels seem to be 
> time-aligned, but there is a huge phase offset between the two 
> channels.  I've observed that the phase offset varies across different 
> frequencies.
>
> So my question is -- why is there a phase offset between the 2 
> channels?  Is there anything that can be done to correct it?
>
> Thanks for your help,
>
> Liz
>
>
>
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> USRP-users at lists.ettus.com
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There may not be.  In the past, the scope sink has had issues with 
proper phase display.  If you plot it as a complex pair instead, it 
maintains proper phase
   display.

Also, what version of UHD are you using?


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