Re: [Discuss-gnuradio] Burg spectral estimation
On Fri, Mar 26, 2010 at 01:25:41PM -0400, Brian Padalino wrote:
> If you don't mind, I am curious of your experience of the Burg versus
> Welch implementation and results - which do you prefer? It looks like
> Burg translates to frequency domain first, and Welch stays in the time
> domain? Any idea how much of the bandwidth can be occupied before the
> algorithms are not relatively accurate anymore? In the presence
> high-noise, are the algorithms still able to detect the tones in your
> current setup?
Welch is quite similar to what the GR FFT sink does, and will work with
any kind of spectral content (it is "non-parametric"). Burg needs some
a-priori knowledge of what you're about to expect ("parametric") and
will only operate well if your a-priori assumption reflect the
signal(s).
Actually, it estimates the filter coefficients of an AR process
(so, technically, it operates in the z-domain). The spectral estimation
output is gathered by running that result through an FFT.
In high-noise, and with little knowledge, you have no choice but use
Welch. A cool application of Burg is to track narrow-band interferers
from only a handful of samples. The pictures on
https://www.cgran.org/wiki/SpecEst were made with a few thousand samples
for Welch, and only 512 samples for Burg (and way less calculations).
Cheers
MB
--
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)
Dipl.-Ing. Martin Braun
Research Associate
Kaiserstraße 12
Building 05.01
76131 Karlsruhe
Phone: +49 721 608-3790
Fax: +49 721 608-6071
www.cel.kit.edu
KIT -- University of the State of Baden-Württemberg and
National Laboratory of the Helmholtz Association
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Re: [Discuss-gnuradio] Burg spectral estimation
On Sat, Mar 27, 2010 at 10:12:33AM +0100, Jens Elsner wrote: > > Have you considered and rejected Pisarenko estimtion techniques or just > > not tried them yet? > > Eigenspace based methods are of course very another interesting thing to > make available > in GNU Radio - if we find students willing to implement this as part of > their course work > in Karlsruhe, Martin and I will gladly support them (anyone reading this? > :). Actually, there already has been some work in this direction, but MUSIC et al are numerically very demanding (estimate autocorrelation matrix AND do an eigenvalue decomposition). I'm therefore not convinced they are massively useful for radio applications (in particular, with real time constraints). Something I'd like to have in the toolbox are cyclostationary spectral estimation methods (FAM, SSCD etc), and I'm hoping to add these some time soon (as in, this year). Cheers, MB -- Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin Braun Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-3790 Fax: +49 721 608-6071 www.cel.kit.edu KIT -- University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association pgpaFnrL7GiuK.pgp Description: PGP signature ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Burg spectral estimation
Hi Bob, On Fri, 26 Mar 2010 21:02:19 -0400, Robert McGwier wrote: > Jens: > > Have you considered and rejected Pisarenko estimtion techniques or just not > tried them yet? The original application was narrow band interference suppression in DSSS systems. Burg's method works quite well as it automatically gives one the filter coefficients for the suppression filter. Eigenspace based methods are of course very another interesting thing to make available in GNU Radio - if we find students willing to implement this as part of their course work in Karlsruhe, Martin and I will gladly support them (anyone reading this? :). Jens ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Burg spectral estimation
Jens: Have you considered and rejected Pisarenko estimtion techniques or just not tried them yet? Thank you for your efforts Bob On Fri, Mar 26, 2010 at 6:58 PM, Jens Elsner wrote: > Hi Brian, > > >> we've done some work to our 'Spectral Estimation Toolbox' and added > >> Burg's algorithm for spectral estimation. It's all on CGRAN, see > >> https://www.cgran.org/wiki/SpecEst > > > > This is good stuff; thanks for sharing! > > > > If you don't mind, I am curious of your experience of the Burg versus > > Welch implementation and results - which do you prefer? It looks like > > Burg translates to frequency domain first, and Welch stays in the time > > domain? Any idea how much of the bandwidth can be occupied before the > > algorithms are not relatively accurate anymore? In the presence > > high-noise, are the algorithms still able to detect the tones in your > > current setup? > > Welch's and Burg's method are very different approaches to spectrum > estimation > and both have their pros and cons. Burg can be better if fewer samples > are available, but one has to be careful when choosing the filter order > (model complexity). > > These questions are best answered in detail in the very good book by > Stoica/Moses "Spectral Analysis of Signals", Prentice Hall, 2005. > > Best regards, > Jens > > > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Burg spectral estimation
Hi Brian, >> we've done some work to our 'Spectral Estimation Toolbox' and added >> Burg's algorithm for spectral estimation. It's all on CGRAN, see >> https://www.cgran.org/wiki/SpecEst > > This is good stuff; thanks for sharing! > > If you don't mind, I am curious of your experience of the Burg versus > Welch implementation and results - which do you prefer? It looks like > Burg translates to frequency domain first, and Welch stays in the time > domain? Any idea how much of the bandwidth can be occupied before the > algorithms are not relatively accurate anymore? In the presence > high-noise, are the algorithms still able to detect the tones in your > current setup? Welch's and Burg's method are very different approaches to spectrum estimation and both have their pros and cons. Burg can be better if fewer samples are available, but one has to be careful when choosing the filter order (model complexity). These questions are best answered in detail in the very good book by Stoica/Moses "Spectral Analysis of Signals", Prentice Hall, 2005. Best regards, Jens ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Burg spectral estimation
On Fri, Mar 26, 2010 at 10:05 AM, Martin Braun wrote: > Hi, > > we've done some work to our 'Spectral Estimation Toolbox' and added > Burg's algorithm for spectral estimation. It's all on CGRAN, see > https://www.cgran.org/wiki/SpecEst > > Things aren't 100% perfect, probably due to the high number of > multiplications numerical accuracy is sometimes a bit off when compared > to Matlab and Octave (which are quite different themselves!), but it > works nicely so far when all you want to do is estimate spectra. > > One of our students rigged a demo in which a narrow-band signal was > nicely tracked by the algorithm; I'll hopefully add that soon along with > GRC bindings. This is good stuff; thanks for sharing! If you don't mind, I am curious of your experience of the Burg versus Welch implementation and results - which do you prefer? It looks like Burg translates to frequency domain first, and Welch stays in the time domain? Any idea how much of the bandwidth can be occupied before the algorithms are not relatively accurate anymore? In the presence high-noise, are the algorithms still able to detect the tones in your current setup? Sorry for all the questions, but this is very interesting! Again, thanks for sharing. Brian ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Burg spectral estimation
On 03/26/2010 07:05 AM, Martin Braun wrote: Hi, we've done some work to our 'Spectral Estimation Toolbox' and added Burg's algorithm for spectral estimation. It's all on CGRAN, see https://www.cgran.org/wiki/SpecEst Things aren't 100% perfect, probably due to the high number of multiplications numerical accuracy is sometimes a bit off when compared to Matlab and Octave (which are quite different themselves!), but it works nicely so far when all you want to do is estimate spectra. One of our students rigged a demo in which a narrow-band signal was nicely tracked by the algorithm; I'll hopefully add that soon along with GRC bindings. Thanks for doing this, and especially for releasing it and making a detailed page on CGRAN. I know this will be of general interest. Matt ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Burg spectral estimation
Hi, we've done some work to our 'Spectral Estimation Toolbox' and added Burg's algorithm for spectral estimation. It's all on CGRAN, see https://www.cgran.org/wiki/SpecEst Things aren't 100% perfect, probably due to the high number of multiplications numerical accuracy is sometimes a bit off when compared to Matlab and Octave (which are quite different themselves!), but it works nicely so far when all you want to do is estimate spectra. One of our students rigged a demo in which a narrow-band signal was nicely tracked by the algorithm; I'll hopefully add that soon along with GRC bindings. Cheers MB -- Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin Braun Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-3790 Fax: +49 721 608-6071 www.cel.kit.edu KIT -- University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association pgp0BWEY4wWXe.pgp Description: PGP signature ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
