Thanks for the suggestion Marcus. I tried adjusting those settings by using the following command:
uhd_usrp_probe --args="serial=123456, recv_frame_size=4096,num_recv_frames=4096" The 123456 is replaced with the actual serial number of the usrp1 when I run the command. When I run that command it shows the USRP1 configuration settings and the daughtercard and then at the bottom it says "Segmentation fault (core dumped)". This happens with other values of recv_frame_size and num_recv_frames. Does anyone know what I'm doing wrong or is this even the right way to change those settings? What are the default values in case I need to set them back to what they were? I couldn't find this anywhere in the UHD documentation. Thank you, - Tom ________________________________ From: Marcus D. Leech <[email protected]> To: Tom Hendrick <[email protected]> Cc: "[email protected]" <[email protected]> Sent: Wednesday, February 20, 2013 9:53 AM Subject: Re: [Discuss-gnuradio] USRP1 4 Channel Subdev Issue 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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