[USRP-users] X3X0 SBX corrupted samples?

Hervé BOEGLEN herve.boeglen at univ-poitiers.fr
Thu Oct 9 10:48:05 EDT 2014


Hello Claude,

I had the same type of problem with an X310 + 2 CBX boards (see my past 
posts on the list). The received signal on channel B was always worse 
than channel A. Indeed, on channel B the noise floor was 40 dB higher 
than on channel A.

My problem was solved by upgrading to UHD 003.007.003 (+ new firmware 
images). As Martin Braun mentioned, there were some bugs in the FPGA 
code solved by this release (at least for my problem).

Concerning the LO locking, I have a GPSDO kit and get sometimes the 
lo_locked not locked message but It happens in average once every 10 runs.

Best regards

Hervé


Le 09/10/2014 15:30, LEMENAGER Claude via USRP-users a écrit :
>
> Hello,
>
> I sample at least two channels (SBX 120) from one or multiple X310 
> boards each equipped with two SBX radio boards.
>
> I uses NIUSRPRIO_PCIEèUHD003.007.002 èGnuradio 3.7.5 (built for this 
> UHD under UBUNTU 14.04LTS).
>
> The input is connected to a CW generator. The channels definition is 
> A:0 B:0, antenna is RX2 in all cases.
>
> The problems :
>
> 1)I receive a warning concerning lo_locked no locked after timeout for 
> each channel (I read a discuss where this fact was given)
>
> 2)When I connect the A:0 channel on a gnuradio scope, this seems OK (I 
> and Q parts). When I connect a B:0 channel (from any X310 board) I 
> receive the CW wave plus spurious (sort of dirac through a filter) 
> generally starting on Q channel but not only. This look like an 
> erroneous sample (digitally speaking for example just an incorrect bit 
> in the LSBs) before DDC. The spurious looks like periodic but the 
> period seems to change with radio frequency (to confirm)
>
> Did somebody encounters this problem?
>
> If yes, is there a solution.
>
> I plan to try to reproduce this (or to see if it's the same) with UHD 
> directly accessed BY a C++ application.
>
> Regards,
>
> Claude Leménager
>
> P.S. Conclusion about preceding discussion (june) about PCIe 
> interface: The HP PC on which I made my firsts experiences was 
> equipped with one of the first generation PCIe chip. So it failed to 
> interface with X310. I now uses a last generation pc and then there is 
> no problem except for what I mention above. Thanks for support.
>
>
>
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