I have a simple GRC flowgraph that transmits a complex sine wave on a
UHD USRP2 with a WBX, receives on a USRP2 with a DBSRX, and displays the
output on a scope. The two boxes are connected via a 30dB Mini-Circuits
attenuator. Mostly the output looks as I expected, but every 350
microseconds or so there’s a glitch that looks like the receiver stops
and starts. You can see the effect in the screen capture below (or in
the PNG at https://public.me.com/mepard in the gnuradio folder, where
you’ll also find the flowgraph).
I’m using current UHD and gnuradio code via git on a very capable
machine running Ubuntu 10.04. System Monitor shows one CPU at 100%, one
at 25 - 40% and the others blow 25%. Wireshark shows a lot of activity
on the control port for the receiver, but I haven’t deciphered the
packets (anyone have a UHD Dissector?).
Any idea what is causing this or how I should troubleshoot it?