Re: [Discuss-gnuradio] USRP Under Flow

[Philip Balister]

On 03/16/2010 06:51 AM, halidziya yerebakan wrote:
> Hi all;
>
>         Thanks to Mr. Balister I run USRP on BeagleBoard (
> http://www.opensdr.com/node/17) . But it doesn't give any sound when I try
> to listen FM radio. I think there is some mismatch in sampling rates or data
> format. I read other mail list archives but they didn't solve my problem.
> Here is my console :
>
> address@hidden:/usr/share/gnuradio/examples/usrp# ./usrp_wfm_rcv_nogui.py
> Using RX d'board A: Basic Rx
> > > > gr_fir_fff: using cortex_a8
> Freq: 100.1M  Volume:0.100000  Setting:FREQ
> OK
> aUaUaUaUaUaUaUaUuOaUaUaUaUaUuOaUaUaUaUaUuOaUaUaUaUaUuOaUaUaUaUaUuOaUaUaUaUaUuOaUaUaUaUuOaUaUaUaUaUuOaUaUaU
>
> (No Sound Here goes like this )

Run oprofile, find the code that takes all the time, optimize using 
NEON, repeat :)

The sample rate conversions will be the CPU hogs for this waveform. It 
looks like you are using an optimized fir filter already, but work 
through the sample rates at each step. It is possible the audio out is 
doing another rate conversion. Also, the gnuradio block may create a 
very long fir filter, you can adjust the filter design settings to 
reduce the number of taps.

It will work, but you do not have many GHz of cpu to cover up 
in-efficient design decisions :)

Philip



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