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Re: [Discuss-gnuradio] Moon Bounce Experiment
From: |
Joseph Craig |
Subject: |
Re: [Discuss-gnuradio] Moon Bounce Experiment |
Date: |
Wed, 20 Oct 2010 18:49:21 -0600 |
Hi Marcus,
Thanks for the quick reply...
On Oct 20, 2010, at 5:51 PM, Marcus D. Leech wrote:
> On 10/20/2010 07:13 PM, Joseph Craig wrote:
>> I have managed to install gnuradio and run usrp_fft.py with success!
>>
>> Now for the questions...
>>
>> 1) I'm always seeing... "Exception RuntimeError: 'maximum recursion depth
>> exceeded while calling a Python object' in <type 'exception.AttributeError'>
>> ignored ". What does this mean, and how to fix it?
>>
> In what application are you seeing this error?
python
>
>> 2) How do I save the I/Q stream to disk? I'm interested in the maximum bit
>> resolution for the best dynamic range. I just want the raw time samples.
>>
> You should investigate gnuradio-companion (GRC), which allows you to put
> a signal processing
> graph together graphically--like LEGO building blocks. You can very
> easily put together a
> "baseband recorder" application in about 5 minutes this way.
5 minutes is pretty enticing seeing how this has to be working friday. How
long does it take to setup GRC? Is there a guide?
>
>> 3) Some of the examples (like usrp_wfm_rcv.py) spit out "...aUaUaUaUaU..."
>> to the console and the sound is choppy. What does this mean, and is there a
>> way to turn it off?
>>
> It means that you're experiencing a audio underrun, likely because your
> processing chain
> can't "keep up". Perhaps because you haven't specified a high enough
> decimation, and
> the chain is trying to keep up with a unpleasantly-large torrent of data.
ah, yes. should have thought of this. I will check out increasing the
decimation.
>
>> 4) Is it possible to tweak parameters such as quadrature downconverter
>> bandwidth/decimation, etc?
>>
>> thanks,
>> Joe Craig
>>
>>
> Yes, absolutely. Most of the example programs take a "-d" option that
> controls decimation
> in the USRP hardware. For example, if you only wanted 1MHz bandwidth,
> you'd use a
> "-d" option to the examples (like usrp_fft.py) of "-d 64", which will
> give you 1Msps of
> complex samples between the USRP and the host--because the A/D in the
> USRP is
> 64Msps. For the USRP2, the A/D operates at 100Msps, so you'd need to
> adjust your
> decimation appropriately.
Got it!
>
> You should keep in mind that except for trivial algorithms at modest
> bandwidths, you'll need
> a fairly-decent computer to get the best results from your Gnu Radio
> experiments. Although
> I think you mentioned that at first you only want to record baseband
> data to disk at 1Msps,
> I'm guessing you'll want to go beyond that at some point.
it's a year old linux box we were using for fairly high bandwidth recording
from ethernet, so it should be ok.
Joe
>
> I'd explore gnuradio-companion as well.
>
> Good luck!
>
> --
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
>
>
>
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> Discuss-gnuradio mailing list
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- [Discuss-gnuradio] Moon Bounce Experiment, Joseph Craig, 2010/10/20
- Re: [Discuss-gnuradio] Moon Bounce Experiment, Joseph Craig, 2010/10/20
- Re: [Discuss-gnuradio] Moon Bounce Experiment, Eric Blossom, 2010/10/20
- Re: [Discuss-gnuradio] Moon Bounce Experiment, Joseph Craig, 2010/10/21
- Re: [Discuss-gnuradio] Moon Bounce Experiment, Marcus D. Leech, 2010/10/21
- Re: [Discuss-gnuradio] Moon Bounce Experiment, Joseph Craig, 2010/10/22
- Re: [Discuss-gnuradio] Moon Bounce Experiment, Marcus D. Leech, 2010/10/22
- Re: [Discuss-gnuradio] Moon Bounce Experiment, Joseph Craig, 2010/10/22