Josh.. Thanks, real time scheduling is enabled, and I run my python script with sudo and I do not see the typical failure message saying real-time was not enabled.
When I run the C++ program in one terminal and output the modulated signal to a normal file, I can read that file in with my python script and see the output on the USRP with no gaps like I was seeing before. The problem is that this isn't real-time and I am writing to a file with the C++ program that grows with time. I did however not see any uU underruns with the USRP so I am pretty sure the laptop can handle running both the C++ and the python script at the same time. I'm guessing its some type of buffer size issue. The C++ program flushes packet by packet. When I run the C++ program and output to a fifo file and do cat tempfifo.dat > check.dat, the check.dat shows none of that latency or zero signal when I open it afterwards. Could it be that the USRP or GRC script has a much smaller buffer size than the packet generated by the C++ program? Does anyone else have any ideas on what I should try? Thanks-Tom --- On Mon, 3/28/11, Josh Blum <j...@joshknows.com> wrote: From: Josh Blum <j...@joshknows.com> Subject: Re: [Discuss-gnuradio] USRP Streaming Latency To: discuss-gnuradio@gnu.org Date: Monday, March 28, 2011, 8:54 PM > I also see uU from the GRC script output about every 5 or so seconds. > Does anyone have any idea if this is a FIFO problem, or is it a > USRP/GRC issue? I am using a Duo core SU7300 laptop so I would think > it should run OK real-time unless the C++ and GRC script demand much > more processing power when used at the same time. Does anyone know > any tricks I can try? > The U printed means underflow, the host does not feed the USRP fast enough. Sometimes enabling RT scheduling on the flow graph can help with this. -Josh _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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