Hello,
I'm trying to do fundamental frequency detection with analog (filters
and PLLs) and a microprocessor (PIC) but the results are very bad.
So I'm thinking about how much would cost a DSP that could do this:
Sample a little portion of audio. It would be a note on a guitar or
another instrument.
Perform FFT on it do determine aproximate lowest frequency
Perform low-pass or band-pass filtering at the frequency
detected by the FFT process
Measure the period of the waveform
Show the results on an LCD or some LEDs, or send it to a
microprocessor.
I think this is the basics of doing frequency tracker for an
instrument-tuner or a guitar synthesizer.
Can anyone here help me on this project?
Thank you very much,
Brusque
-----------------------------
Edson Brusque C.I.Tronics Lighting Designers Ltda
Research and Development Blumenau - SC - Brazil
Say NO to HTML mail www.citronics.com.br
-----------------------------
Cheap DSP for audio
Started by ●June 29, 2002
Reply by ●July 1, 20022002-07-01
Hi
You need to confirm whether other peaks in FFT are positioned as integer
multiples of fundamental.
Once you get the period of the waveform, do an autocorrelation for the
samples corresponding to a period.( Alternatively, you could check it in
FFT itself, but it may be difficult to judge since the bin frequencies
may not match exactly with fundamental and harmonics). This will confirm
whether this is indeed the fundamental.
Regards
arun
-----Original Message-----
From: Edson Brusque (Listas) [mailto:brusque.listas@brus...]
Sent: Saturday, June 29, 2002 6:24 PM
To: audiodsp@audi...
Subject: [audiodsp] Cheap DSP for audio
Hello,
I'm trying to do fundamental frequency detection with analog
(filters
and PLLs) and a microprocessor (PIC) but the results are very bad.
So I'm thinking about how much would cost a DSP that could do this:
Sample a little portion of audio. It would be a note on a guitar
or
another instrument.
Perform FFT on it do determine aproximate lowest frequency
Perform low-pass or band-pass filtering at the frequency
detected by the FFT process
Measure the period of the waveform
Show the results on an LCD or some LEDs, or send it to a
microprocessor.
I think this is the basics of doing frequency tracker for an
instrument-tuner or a guitar synthesizer.
Can anyone here help me on this project?
Thank you very much,
Brusque
-----------------------------
Edson Brusque C.I.Tronics Lighting Designers Ltda
Research and Development Blumenau - SC - Brazil
Say NO to HTML mail www.citronics.com.br
-----------------------------
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Reply by ●July 1, 20022002-07-01
>-----Original Message----- >From: Edson Brusque (Listas) [mailto:brusque.listas@brus...] >Sent: Saturday, June 29, 2002 6:24 PM >To: audiodsp@audi... >Subject: [audiodsp] Cheap DSP for audio > >Hello, > > I'm trying to do fundamental frequency detection with analog >(filters >and PLLs) and a microprocessor (PIC) but the results are very bad. > > So I'm thinking about how much would cost a DSP that could do this: > > Sample a little portion of audio. It would be a note on a guitar >or > another instrument. > Perform FFT on it do determine aproximate lowest frequency > Perform low-pass or band-pass filtering at the frequency > detected by the FFT process > Measure the period of the waveform > Show the results on an LCD or some LEDs, or send it to a > microprocessor. > > I think this is the basics of doing frequency tracker for an >instrument-tuner or a guitar synthesizer. > > Can anyone here help me on this project? > > Thank you very much, > > Brusque > >----------------------------- >Edson Brusque C.I.Tronics Lighting Designers Ltda >Research and Development Blumenau - SC - Brazil >Say NO to HTML mail www.citronics.com.br >----------------------------- > You might look into the Goertzel method of tone detection. Analog Devices has application information in Digital Signal Processing Applications Using the ADSP-2100 Family: Vol 1 Ch 14 & Vol 2 Ch 8. We have a product that would be a good platform for this idea. Our DSP-8300 DSP function module has an ADI ADSP-2186M DSP, an AC-97 stereo codec and a Flash based loader. You could send detected results out the serial port. Details are at our web site. There is also a link to the Analog Devices books that I previously mentioned (they are downloadable). Al Clark Danville Signal Processing, Inc. -------------------------------- Purveyors of Fine DSP Hardware and other Cool Stuff Available at http://www.danvillesignal.com
Reply by ●July 2, 20022002-07-02
Hi Suppose you extract one period of the waveform and cross-correlate with 2-3 periods of the original waveform, this effect may not be observed but for the last correlation peak. (But one thing to be noted is that the period can be accurately estimated if the waveform itself has very good correlation property.) Regards arun -----Original Message----- From: sriraman_sri [mailto:sriraman_sri@srir...] Sent: Tuesday, July 02, 2002 5:52 PM To: arun d. naik Subject: Re: Cheap DSP for audio Hi!, While using the autocorrelation function, try using a modified autocorr, for the normal autocorr goes on decreasing in amplitude. So you can lift it by using a weighting function. bye --- In audiodsp@y..., "arun d. naik" <arun.naik@w...> wrote: > Hi > You need to confirm whether other peaks in FFT are positioned as integer > multiples of fundamental. > Once you get the period of the waveform, do an autocorrelation for the > samples corresponding to a period.( Alternatively, you could check it in > FFT itself, but it may be difficult to judge since the bin frequencies > may not match exactly with fundamental and harmonics). This will confirm > whether this is indeed the fundamental. > Regards > arun > > > -----Original Message----- > From: Edson Brusque (Listas) [mailto:brusque.listas@c...] > Sent: Saturday, June 29, 2002 6:24 PM > To: audiodsp@y... > Subject: [audiodsp] Cheap DSP for audio > > Hello, > > I'm trying to do fundamental frequency detection with analog > (filters > and PLLs) and a microprocessor (PIC) but the results are very bad. > > So I'm thinking about how much would cost a DSP that could do this: > > Sample a little portion of audio. It would be a note on a guitar > or > another instrument. > Perform FFT on it do determine aproximate lowest frequency > Perform low-pass or band-pass filtering at the frequency > detected by the FFT process > Measure the period of the waveform > Show the results on an LCD or some LEDs, or send it to a > microprocessor. > > I think this is the basics of doing frequency tracker for an > instrument-tuner or a guitar synthesizer. > > Can anyone here help me on this project? > > Thank you very much, > > Brusque > > ----------------------------- > Edson Brusque C.I.Tronics Lighting Designers Ltda > Research and Development Blumenau - SC - Brazil > Say NO to HTML mail www.citronics.com.br > ----------------------------- > > > > > _____________________________________ > Note: If you do a simple "reply" with your email client, only the author > of this message will receive your answer. You need to do a "reply all" > if you want your answer to be distributed to the entire group. > > _____________________________________ > About this discussion group: > > To Join: audiodsp-subscribe@y... > > To Post: audiodsp@y... > > To Leave: audiodsp-unsubscribe@y... > > Archives: http://groups.yahoo.com/group/audiodsp > > Other DSP-Related Groups: http://www.dsprelated.com > > > ">http://docs.yahoo.com/info/terms/ > > > > **************************Disclaimer********************************** **************** > > Information contained in this E-MAIL being proprietary to Wipro Limited is 'privileged' > and 'confidential' and intended for use only by the individual or entity to which it is > addressed. You are notified that any use, copying or dissemination of the information > contained in the E-MAIL in any manner whatsoever is strictly prohibited. > > ********************************************************************** ******************
