[Discuss-gnuradio] USRP-Overrun Problem

[Eder Matthias]

Hello,

i'm newbe at Gnuradio and i started with a simple FM receiver project.
I use a USRP1 interface with a TV Rx rev3 daugtherboard and gnuradio 
3.3, installed on a Ubuntu 9.04 distribution.
The CPU is a AMD X2 4800+, ramsize is 1GB.

The good news: The FM-receiver works very well.
The bad news: "uOuOuOuO"-messages


The USRP parameters are:
freq: 102,4 MHz
decimation: 256

Realtime scheduling is enabled too.

The decimation factor of 250 devides the full usb bandwith of 64MB/s to 
256kB/s.
In my point of view, this should be no problem for the pc to read this 
amount of data.
Nevertheless i get many of the overrun messages ("uO").
The effect of the lost messages is hearable to (of course!). I can hear 
a cyclic! click.

That means, that the pc isn't able to read the USB data fast enough. But 
why?
The CPU load is about 15% of each core. But gnuradio isn't listed in the 
process-list. So i cannot say what load is produced by gnuradio itself.

Does anybody can give me any hint, where the problem could be?

Thank you for your help.

Matthias