[Discuss-gnuradio] USRP2 Underruns

[James Streitman]

Hello,

I've been getting a series of underruns when running a USRP2 at 10MHz (Interpolation = 10) using RTS and a fast machine. I plugged a serial cable into the UART and can see one or more 'U's pop up on the screen. Depending on how many custom blocks I have, the occurrence of a U can take from 2 minutes to an hour. The average processor usage varies with which blocks I use but only over a range from 20% to 35% with no spikes above 40% according to gnome-system-monitor.

More-over, if I make a simple flowgraph in GRC of the following:
GLFSR(23, True, 0,1) -> char_to_float -> float_to_complex -> USRP2_sink(Interp = 10, freq = 2.4e9, gain = 20, Clock: Lock to external SMA) 

(With Real Time scheduling enabled)

I still get underruns!

Anyone have any ideas on what might cause my underruns or just underruns in general?

Thanks,

James Streitman