[USRP-users] B210/B200mini: sc12 format still broken?

Emanuel.Staudinger at dlr.de Emanuel.Staudinger at dlr.de
Thu Feb 7 07:38:50 EST 2019


Dear Ettus team,

I'm currently using a B210 and a B200mini with the latest released UHD version on an Ubuntu 18.04LTS and Ubuntu 18.10 computer.
Streaming from a B210 (single channel RX) with the sc12 wire format seems to be broken: If I have a look at the received I/Q signal I see a lot of large transient spikes in the received signal with a repetition of about 106us. It looks like a saw tooth of Diracs functions.

Firstly, I thought that my USRPs are broken. I changed them and discovered the same.
I then reverted the UHD release version back to 3.12:

·         3.12 results in a vrt bad header error if the sc12 wire format is used --> I think I wrote an Email for that some time ago

·         3.13.0.0 --> I tried all versions up to 3.13.1.0 and discovered the same problem for all of them --> the same saw-tooth Dirac functions.

Changing the wire format to sc8 or sc16 works fine; no problems there.
I also thought that maybe the sc12 to fc32 conversion is somehow wrong resulting in this effect in Gnuradio. That's not the case: I streamed the samples to disk with a sc12 wire format and sc16 cpu format, and had a look at the received signal in MATLAB --> the saw-tooth Dirac functions are there.

Can you please have a look at it.
Simply use a B210 or B200mini, set it to 25 MHz or 30.72 MHz of sampling rate, use a sc12 wire format, and use a time sink in Gnuradio. You should see it directly.

Best regards,
Emanuel

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