Walsh Function Primer

[Neil Johnson]

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From: Martin Czech <martin.czech at itt-sc.de>
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Date: Tue, 5 Aug 1997 08:23:51 +0200 (MET DST)
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To: Neil.Johnson at camcon.co.uk
Subject: Re: Walsh Function Primer
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     Martin (and list),
     
     I use a digital oscillator to generate the clock signal.  This is 
     controlled by an 8051 microprocessor using a pitch table:
        note + pitchbend + mod -> TABLE -> 24 bit number -> Oscillator
     
     For frequency modulation you could hook up an ADC to the micro and get 
     it to read the ADC every, say, 1ms and add that value to the pitch 
     number.  Then you can feed any signal into the ADC (EG, LFO, joystick, 
     etc) and modulate the pitch.  As long as you don't want AF modulation 
     you should be alright up to a few hundred Hz modulation frequency.
     
     Neil
     ----
     
     
     
     +---------------------------+-----------------------------+
      Neil Johnson               * All thoughts and opinions
      Cambridge Consultants Ltd  * expressed here are my own.
      email: nj at camcon.co.uk     * Heck, even _I_ don't believe
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______________________________ Reply Separator _________________________________
Subject: Re: Walsh Function Primer
Author:  Martin Czech <martin.czech at itt-sc.de> at Internet-PO
Date:    05/08/97 08:23


     
Thank you for your interesting explanation. 
(No irony here).
I once learned, that synthesis could be done 
with a lot of orthogonal functions, but the name Walsh 
never was heard.
     
But one question remains : 
How to get a rather high clock frequency for the generator? 
Precision VCO work at 20Hz-20KHz, and at the top end there are 
already difficulties with delays etc.
Flat tracking. How to create frequencys
say 128 times higher, without using a pll or a divider?
     
How do you do this?
     
     
m.c.