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Re: [Discuss-gnuradio] USRP Under Flow

From: Jeff Brower
Subject: Re: [Discuss-gnuradio] USRP Under Flow
Date: Tue, 16 Mar 2010 13:59:42 -0600 (CST)
User-agent: SquirrelMail/1.4.2-1


> 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 :)

At what rates are the OMAP 3530 cores running on the Beagle board?  The web 
page says "up to" 600 MHz for the ARM A8
and up to 430 MHz for the C64x+ core.  Sometimes TI eval/dsk boards don't 
always run at max rate...

Also, do you know if anyone has done work to port GNU radio functions over to 
the C64x+ core?  For example you mention
sample rate conversion, that would be very suitable to offload onto the DSP.


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