# PSD Display from USRP Data

**URL:** <https://www.ruby-forum.com/t/psd-display-from-usrp-data/149715>\
**Category:** GNU Radio\
**Created:** [September 28, 2008, 10:33pm UTC](https://www.ruby-forum.com/t/psd-display-from-usrp-data/149715 "2008-09-28T22:33:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Rahman\_Doost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/838e76/32.png) [@Rahman\_Doost](https://www.ruby-forum.com/u/Rahman_Doost)\
**Post date:** [September 28, 2008, 10:33pm UTC](https://www.ruby-forum.com/t/psd-display-from-usrp-data/149715/1 "2008-09-28T22:33:26Z")

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Hello G.s,

I am very new to GNU Radio. I am trying to develop a python program that  
graphically displays data from USRP which sweeps a user-defined  
frequency  
band from down-freq to up-freq. USRP is tuned to divide the input band  
to 3  
MHz sub-bands and return the power spectral density. I am using  
usrp.source\_c to connect to the board. I have two threads, one running  
GUI  
and shows the input of PSD; the second one stores the FFT components of  
each  
sub-band to a file. In the GUI, I use fftsink2.usrp\_sink\_c() to display  
the  
PSD for the currect scanning band. But what I can not display is the  
current  
sub-band whose FFT result are plotted by usrp\_sink\_c. That’s because on  
the  
X-axis of the plot I have the center frequency 0 and freq ranging from  
-1.5  
MHz to 1.5 MHz. What I need is either having the whole spectrum being  
plotted with history, not just the current scanned sub-band, or  
representing  
the currect frequency sub-band which is being scanned. I was wondering  
If  
someone can help me out on this.

Regards,  
Rahman Doost

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<div class="post-metadata">

**Author:** ![Rahman\_Doost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/838e76/32.png) [@Rahman\_Doost](https://www.ruby-forum.com/u/Rahman_Doost)\
**Post date:** [September 29, 2008, 4:06am UTC](https://www.ruby-forum.com/t/psd-display-from-usrp-data/149715/2 "2008-09-29T04:06:38Z")

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Rahman Doost wrote:

> I am very new to GNU Radio. I am trying to develop a python program that  
> graphically displays data from USRP which sweeps a user-defined  
> frequency band from down-freq to up-freq. USRP is tuned to divide the  
> input band to 3 MHz sub-bands and return the power spectral density.

I have code that sweeps a user-defined frequency band, transmits  
compressed FFT  
spectral data over the network, presents the full swept spectrum (up to  
50-2400  
MHz) as a scrollable plot using QWT, detects peaks in the power  
spectrum, tries  
to automatically characterize and identify each peak in numerous  
spectrum usage  
databases, displays the spatially referenced records in Google Earth and  
Celestia, logs detected signals according to user-defined criteria, and  
handles  
manual (click-to-tune) and automatic tuning of handoff intercept  
receivers. At  
the moment, my code depends on versions of GNU Radio and GRC from about  
two  
years ago. Since there’s interest in doing something similar, I’ll  
update it  
to work with the current trunk and post it somewhere, hopefully in the  
next few  
weeks.

---

<div class="post-metadata">

**Author:** ![Rahman\_Doost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/838e76/32.png) [@Rahman\_Doost](https://www.ruby-forum.com/u/Rahman_Doost)\
**Post date:** [December 23, 2011, 3:06pm UTC](https://www.ruby-forum.com/t/psd-display-from-usrp-data/149715/3 "2011-12-23T15:06:32Z")

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Can i get the USRP code ?

Rahman Doost wrote:

> each  
> representing

–  
View this message in context:  
[http://old.nabble.com/PSD-Display-from-USRP-Data-tp19715258p33029436.html](http://old.nabble.com/PSD-Display-from-USRP-Data-tp19715258p33029436.html)  
Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com).