Hi all,
I'm having some issues with the USRP and some latency in the output signal. I
am using a C++ program which modulates a signal and writes to a file
continuously.
When I use a normal file, the C++ program output looks perfect. When I use a
script made in GRC to read the C++ output file, the USRP generated signal also
looks perfect with an oscilloscope.
Now to get the process real-time, when I use mkfifo to tie the C++ and GRC
script together, I notice a problem. The C++ program constructs a packet and
then flushes and repeats continously. I'm sure this is less than the 64KB
buffer size with FIFOs. The GRC script reads from that file and I see the
signal output showing the modulated blocks, but I notice it is not continuous
and there seems to be 1-2 seconds of zero signal, every 5 seconds or so.
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?
Thanks,
Tom
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