[USRP-users] Bad Data from USRP N210 on OS X after many captures

Perelman, Nathan nperelman at LGSInnovations.com
Thu Dec 4 18:15:59 EST 2014

I have an application that uses a USRP N210 and performs repeated short captures, usually retuning between them. On OS X I have found that I get good data for several hours (sometimes as long as a couple days), but eventually the USRP goes into some bad state. Once in this state, all samples in a single capture from the USRP have some near constant I & Q value (which varies +/- 1 over the course of the capture). I have attached a sample packet from a Wireshark capture where you can see the bad data (the USRP in this case was tuned to an empty area of spectrum). If I quit and restart my application (closing and reopening the connection to the USRP), the USRP will return to functioning normally for several hours again.

The captures are all done at 50 or 25 MHz sampling rates and I do observe some captures failing with overruns which my software will retry. I am using OS X 10.9, UHD 3.8.0, an N210r4, and an SBX daughterboard. I have seen this issue with 2 separate USRPs and daughterboards on 2 separate Macbooks.

Any ideas on what could be causing this issue and what I might do to avoid it? Thanks.

-Nathan Perelman

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