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Re: DSP development system pricing!!!

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12/21/1999 6:23 PM

Re: DSP development system pricing!!!

"Got a university/community college handy? "

Yes, currently I am a university student too (though I am also a part time worker), but I suspect I would have time for another course. Is this subject learnable without taking a course? Is it possible to do everything that is done with DSP hardware without using hardware?(*1)( I dont care if a software implementation works slow). Probably the answer for (*1) is yes, but does this mean that I have to do things with software that I would not do with hardware? (For example, finding the period of the wave, the last time that I had tried to use FFT, this was the primary problem of implementation, and I could not find a usable solution - well, looking for the zero crossing points in the integral of the wave function was one idea - but I did not like the idea much).
Thanks,
Kursad

12/21/1999 7:28 PM

quote:
"Is it possible to do everything that is done with DSP hardware without using hardware?"

The minimum hardware you need is an A/D converter so that you can acquire the signals and a D/A if you want to send it back to analog. Special processing hardware is need only if you want realtime or fast processing.

quote:
"For example, finding the period of the wave,..."

There's a "new" technique called Wavelet Transform that is better suited to note recognition than FFT. Oversimplifying, it's like a short time Fourier transform but with constant "Q" bands instead of constant bandwith (that is the frequency resolution is uniform on a log scale).

12/22/1999 5:08 AM
Don Symes	Cool... very cool. If you have a sound card, it is (technically) possible to use the (A/D) ADCs and (D/A) DACs on it. I've seen some articles, but my memory... what was I saying?

12/22/1999 3:22 PM
jraden	Re: Wavelets I've been interested in Wavelets for music making. I've thinking about reading the Chui book, and/or buying the MIT Csound book, which has a chapter on the CD about wavelets. Can anyone recommend any other books that would touch on wavelet use for music?

12/22/1999 5:03 PM

I haven't worked with Wavelets since my thesis (1994) so my references are certainly out of date. On those days anything writen by Mallat, Vetterli or Daubechies was guaranteed to be good.

The following article is the only reference I have that is somewhat related to music:

IEEE Transactions on Information Theory March 1992
Volume 38 Number 2 (Part II) on page 674

"A Generalized Wavelet Transform for Fourier analysis: The Multiresolution Fourier Transform and Its Applications to Image and Audio Signal Analysis" - Wilson, Calway and Pearson.

One section deals with note (pitch) recognition. The big thing here is that it tries to recognize POLIPHONIC music... not just single notes!

12/22/1999 5:05 AM

Re: DSP development system pricing!!!

does this mean that I have to do things with software that I would not do with hardware?

The hardware (DSP CPU) still has to do those things by software, but the hardware is optimized to do the types of operations that make it fast. As I understand it (which ain't much) FFT for filter applications has been supplanted by the FIR/IIR filters [finite impulse response/infinite impulse response] which are implemented as 'shift' registers and multiply/accumulate operations.

The nice thing about the FIR and IIR filters is the total lack of interest in the periodicity of the signal. Get that book and then tell me where to stick it.

12/23/1999 12:10 AM
Kursad Kurt	thanks all! Hmm thanks!

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