Re: [Discuss-gnuradio] FFT Spectral smoothing]
2007/6/29, Aadil Volkwin [EMAIL PROTECTED]: Hi, My apologies for the lengthy silence. I have been out of town and unable to respond to mail. I'm not entirely clear on what you mean when you ask if the smoothing is over time or frequency. In essence, I would like to reproduce an output comparable to that of a spectrum analyser. That is, the GNU FFT show the frequencies and their related power in dB respectively, instantaneously. I would like to average the values of the Power spectrum and obtain an output showing the smoothed/average frequency values over a certain period. for instance say 100 samples of each frequency. Such that the values outputted are more stable and accurate and less eratic. As I am new to GNU_RADIO, I am not aware if the functionality for smoothing is built in and If I would need to write code to do this averaging of values, i'm not quite clear on where to begin. My apologies again for the lengthy delay and look forward and appreciate your assistance regarding this matter. regards, Aadil Volkwin You can use the single pole iir filter to smooth the signal. The single pole filter is also known as a exponential moving average filter. You can find the GNU Radio documentation for it here: http://gnuradio.org/doc/doxygen/classgr__single__pole__iir__filter__cc.html If you want to know more, I can recommend this: http://www.dspguide.com/ch19/2.htm -- Trond Danielsen ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] FFT Spectral smoothing
Aadil Volkwin wrote: i'd like to do spectral smoothing on an FFT in real time through GNU_RADIO. Is there a function that will allow me to do this in the GNU_RADIO modules? Are you referring to smoothing FFT bins over time or over frequency? -- Johnathan Corgan Corgan Enterprises LLC http://corganenterprises.com ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] FFT Spectral smoothing
Peter Monta wrote: I guess he means time. This would greatly improve the FFT demos, since currently there is no video filtering, as the spectrum analyzer folks say. In the current FFT demo, it is possible to right-click on the display and select 'Average'. This will perform low-pass filtering on each FFT bin such that the noise averages to its rms value but the signal peaks remain. This is done in the flow graph by using a gr.single_pole_iir_filter as an exponential averager. You can do this in the waterfall mode as well. -- Johnathan Corgan Corgan Enterprises LLC http://corganenterprises.com ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] FFT Spectral smoothing
Peter Monta wrote: i'd like to do spectral smoothing on an FFT in real time through GNU_RADIO. Is there a function that will allow me to do this in the GNU_RADIO modules? Are you referring to smoothing FFT bins over time or over frequency? I guess he means time. This would greatly improve the FFT demos, since currently there is no video filtering, as the spectrum analyzer folks say. A more flexible spectral estimate would allow showing nice clean noise floors at the expense of a little measurement time. If you right-click in the spectrum window you will see an option for averaging and peak-hold. Matt ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] FFT Spectral smoothing
Hi, i'd like to do spectral smoothing on an FFT in real time through GNU_RADIO. Is there a function that will allow me to do this in the GNU_RADIO modules? If not has anyone attempted it before, or have any suggestions as to how I should go about implementing it myself. Perhaps any ideas of cascading blocks that do exit. Thanks, Aadil ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] FFT Spectral smoothing
2007/6/21, Aadil Volkwin [EMAIL PROTECTED]: Hi, i'd like to do spectral smoothing on an FFT in real time through GNU_RADIO. Is there a function that will allow me to do this in the GNU_RADIO modules? If not has anyone attempted it before, or have any suggestions as to how I should go about implementing it myself. Perhaps any ideas of cascading blocks that do exit. Thanks, Aadil From what I can find, spectral smoothing is not an unambiguous term. Could you please elaborate the problem, preferably the mathematical definition of what you are trying to accomplish. Best regards, -- Trond Danielsen ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
