I tried the suggestion from Marcus and was able to get the USRP1 to
work with 4 real channels. I have a simple GRC script which samples
the USRP at 1MS/s and then resamples the signal to 500kS/s and then
writes to a file. I am getting continuous Overruns with this GRC
script on my laptop.
I have the same GRC script with the older GNURadio and when I ran it
again on the same laptop (I booted up a prior version of ubuntu with
an older gnuradio version that uses the USRP class not UHD) it writes
to file with no Overruns at all. I saw that the custom quad channel
USRP block has an fusb_block and fusb_nblocks setting. These are both
set to 512*32 but if I lower them to something like 64*32 I start to
see the Overruns.
Are there similar type settings I can adjust on the 3.6.2 version of
GRC or GNURadio python scripts to get rid of the overruns? I'm not
sure if this is possible but I would like to not have to boot into an
older ubuntu version when I need 4 real channels. The only thing that
comes to mind is to adjust noutput_items and I tried this but it
didn't eliminate the overruns.
Thank you, -Tom
http://files.ettus.com/uhd_docs/manual/html/transport.html#usb-transport-libusb
The USB parameters shown there can be passed as device args
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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