Re: [Discuss-gnuradio] How to capture the Rx data using uhd_rx_cfile and agree with the uhd_fft Scope mode data

[Josh Blum]

On 09/26/2012 01:36 AM, LD Zhang wrote:
> Hi,
> 
> I did try and made a GRC example of using a USRP Source and a fft sink,
> scope sink, and a file sink to test out the idea.
> 
> When looking at the scope sink, the data is about +/- 2x10^-4. I changed
> the gain of the USRP source block to 20 dB. But nothing happened to the
> signal amplitude. How is this possible?
> 

You mentioned LFRX? There are no configurable gain elements for the LFRX
daughterboard.

If this helps, the various gain ranges are listed for various
daughterboard frontends here:
http://files.ettus.com/uhd_docs/manual/html/dboards.html#basic-rx-and-lfrx

-josh

> Please see the attached GRC if you want to see what I am doing. Thanks.
> 
> LD
> 
>> I could go directly to GRC GUI directly and try to learn to do everything
>>> there. But I think there is value in being able to do this simple thing
>>> from the command line. Your help and suggestions are appreciated.
>>>
>>
>> I will second this motion.
>>
>> All of the hooks are available in the USRP source block, most of which
>> can be changed at runtime with a simple variable widget. Its nice to
>> change setting at runtime to see the effect.
>>
>> Also, you can easily attach a file sink and a scope sink and an fft
>> sink. That way you know that you have captured to file the same thing
>> you are observing.
>>
>> Also, be careful with the format of the file data. Its a binary array of
>> std::complex<float>, not float, not double, etc...
>>
>> -josh
>>
>>
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>