# Audio processing with USRP2 and LFRX

**URL:** <https://www.ruby-forum.com/t/audio-processing-with-usrp2-and-lfrx/230726>\
**Category:** GNU Radio\
**Created:** [July 1, 2014, 8:11pm UTC](https://www.ruby-forum.com/t/audio-processing-with-usrp2-and-lfrx/230726 "2014-07-01T20:11:29Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [July 1, 2014, 8:11pm UTC](https://www.ruby-forum.com/t/audio-processing-with-usrp2-and-lfrx/230726/1 "2014-07-01T20:11:29Z")

</div>

Hi, I am attempting to use the Ettus USRP2 and LFRX daughterboard to  
process a low-frequency audio signal (between DC and 1 KHz). I have had  
no success so far in getting the uhd waterfall sink to display a  
spectrogram of this frequency range at sufficient frequency resolution.  
There seems to be no way to adjust the frequency scale, only the time  
scale and sampling rate. Is there any way to do this or is it just not  
possible with the USRP? The LFRX board is supposed to work down to DC.

I had read in other posts that the USRP firmware’s DC offset correction  
had to be disable, but using the uhd\_usrp\_sink\_sptr.set\_dc\_offset()  
function in python did not seem to make a difference.

Thanks,

James