[USRP-users] X3X0 SBX corrupted samples?

LEMENAGER Claude claude.lemenager at thalesgroup.com
Thu Oct 9 12:10:11 EDT 2014

Thank you very much Hervé.

Claude Leménager


De : Hervé BOEGLEN [mailto:herve.boeglen at univ-poitiers.fr]
Envoyé : jeudi 9 octobre 2014 16:48
Cc : usrp-users at lists.ettus.com
Objet : Re: [USRP-users] X3X0 SBX corrupted samples?

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


Le 09/10/2014 15:30, LEMENAGER Claude via USRP-users a écrit :

I sample at least two channels (SBX 120) from one or multiple X310 boards each equipped with two SBX radio boards.
I uses NIUSRPRIO_PCIE==>UHD003.007.002 ==>Gnuradio 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.


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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