[Discuss-gnuradio] Flow graph freezes up

[Nazmul Islam]

Hello,

My gnuradio application seems to freeze from time to time. I think that this issue was raised before (http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2012-March/003969.html). However, I did not see a solution that would "permanently" fix the problem. 

My application works in a repeated on-off manner. The receiver USRP works in the following way:

1.The flowgraph starts. It runs for 5 second while collecting data and doing some online processing. Thereafter, the flowgraph stops.
2. I do some off-line processing with the stored data for the next 5 seconds
3. The flowgraph is restarted and step 1-2 are repeated.

The flowgraph looks like the following:

USRP Source --> Log power FFT --> Vector to stream --> File Sink.

However, the flow graph freezes from time to time. This freezing occurs once in every 5-10 trials. It is surprising since I hardly see any overrun in the receiver (I am running the USRP at 4 MS/s and performing 4096 point FFT). Besides, I have a python code that pings the USRP every time before starting the flowgraph. 

I am using USRP N210, the latest GNUradio & UHD drivers, Ubuntu 12.04. Any suggestions on resolving this issue will be very appreciated.


Thanks,

Nazmul


-- 
Muhammad Nazmul Islam

Graduate Student
Electrical & Computer Engineering
Wireless Information & Networking Laboratory
Rutgers, USA.