tone detection advice needed/wanted
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From: jacobfenton on 22 Apr 2010 12:25 I am doing tone detection of 4 known frequencies using the Goertzel algorithm. The tones have a large bandwidth that I must be able to detect them, up to +/-4% of the tone value. To do this the Goertzel is set up to have large bin width, which makes the SNR not so good. Is there perhaps another approach that will have similar computation time as the Goertzel, but allow for better SNR? Thanks. -Jacob Fenton
From: Jason on 22 Apr 2010 14:03 On Apr 22, 12:25 pm, "jacobfenton" <jacob.fenton(a)n_o_s_p_a_m.gmail.com> wrote: > I am doing tone detection of 4 known frequencies using the Goertzel > algorithm. The tones have a large bandwidth that I must be able to detect > them, up to +/-4% of the tone value. To do this the Goertzel is set up to > have large bin width, which makes the SNR not so good. Is there perhaps > another approach that will have similar computation time as the Goertzel, > but allow for better SNR? > > Thanks. > > -Jacob Fenton One approach might be to use a bank of bandpass filters around the frequencies of interest. Instead of having 4 fat filters, use 4 clusters of a few narrower filters (you probably want them to overlap a bit). You can keep the SNR at the output of each filter relatively high since they are still narrow. You would have more computations to do, however. Jason
From: jacobfenton on 22 Apr 2010 14:14 >On Apr 22, 12:25=A0pm, "jacobfenton" ><jacob.fenton(a)n_o_s_p_a_m.gmail.com> wrote: >> I am doing tone detection of 4 known frequencies using the Goertzel >> algorithm. The tones have a large bandwidth that I must be able to detect >> them, up to +/-4% of the tone value. To do this the Goertzel is set up to >> have large bin width, which makes the SNR not so good. Is there perhaps >> another approach that will have similar computation time as the Goertzel, >> but allow for better SNR? >> >> Thanks. >> >> -Jacob Fenton > >One approach might be to use a bank of bandpass filters around the >frequencies of interest. Instead of having 4 fat filters, use 4 >clusters of a few narrower filters (you probably want them to overlap >a bit). You can keep the SNR at the output of each filter relatively >high since they are still narrow. You would have more computations to >do, however. > >Jason > Yes, it seems other options I am looking at will require more computations.
From: Clay on 22 Apr 2010 14:56 On Apr 22, 12:25 pm, "jacobfenton" <jacob.fenton(a)n_o_s_p_a_m.gmail.com> wrote: > I am doing tone detection of 4 known frequencies using the Goertzel > algorithm. The tones have a large bandwidth that I must be able to detect > them, up to +/-4% of the tone value. To do this the Goertzel is set up to > have large bin width, which makes the SNR not so good. Is there perhaps > another approach that will have similar computation time as the Goertzel, > but allow for better SNR? > > Thanks. > > -Jacob Fenton Try Vlad's method described here in his paper: http://www.abvolt.com/research/Multitone%20detect-IEEE.pdf IHTH, Clay
From: Rune Allnor on 23 Apr 2010 04:48
On 22 apr, 18:25, "jacobfenton" <jacob.fenton(a)n_o_s_p_a_m.gmail.com> wrote: > I am doing tone detection of 4 known frequencies using the Goertzel > algorithm. The tones have a large bandwidth that I must be able to detect > them, The term 'tone' is usually used about (nearly) monochromatic signals. A 'tone with a wide bandwidth' is pretty much a contradiction in terms. What kinds of signal are you *really* looking for? > up to +/-4% of the tone value. What 'value' is this? Amplitude? Frequency? Something else? > To do this the Goertzel is set up to > have large bin width, which makes the SNR not so good. Is there perhaps > another approach that will have similar computation time as the Goertzel, > but allow for better SNR? It depends on what signals you are working with and what you attempt to do. Rune |