[sdiy] F2V with PIC or AVR?

[dan snazelle]

i could listen to Harry talk about F2V all day long ;)



On Apr 11, 2011, at 2:12 PM, Harry Bissell wrote:

> Usually its some kind of either fixed LPF (usually a very aggressive one), or some adaptive
> or tracking LP filter.  Electro-Harmonix has some examples of each, the guitar micro-synthesizer uses the
> 18db filter, the Deluxe Octave Multiplexer uses a compressor and tracking filter (the tracking filter
> only works with a constant amplitude input signal.  There are other methods, such as a bandpass filter and
> zero crossing detection (Roland GR-500), detecting one peak and a zero cross, detecting successive peaks (Gentle Electric),
> and other methods. 
> 
> I used the New England Digital (Synclavier) detailed in the Calman Gold patent, however I did that for all the wrong reasons :^)
> I had to feed back the CV into a tracking filter to reduce jitter.  
> 
> and thats just methods for guitar, other instruments are easier or harder than that...
> 
> H^) harry
> 
> 
> 
> ----- Original Message -----
> From: David G. Dixon <dixon at interchange.ubc.ca>
> To: 'Harry Bissell' <harrybissell at wowway.com>
> Cc: lanterma at ece.gatech.edu, synth-diy at dropmix.xs4all.nl
> Sent: Mon, 11 Apr 2011 13:24:30 -0400 (EDT)
> Subject: RE: [sdiy] F2V with PIC or AVR?
> 
>> The really tough part is to condition the signal so that you 
>> can get ONLY the fundamental frequency.
> 
> So, what are the steps one must take to isolate the fundamental?  I'm
> assuming some or all of the following: AC coupling (to centre the signal
> about ground), LP filtering (to remove extraneous wiggles which might cross
> zero but not represent the fundamental, such as HF resonance), and
> comparating with hysteresis (to generate a clean square wave).  The LP
> filter could even be tuned to the derived frequency plus a discrete distance
> (like an FBI agent on your tail).
> 
>> Pitch-to-Voltage is the easy part.  Most of the signal 
>> processing involves figuring out when a note begins, when it 
>> ends, and when you can no longer trust the input to be valid 
>> (enter hold mode etc.)
> 
> So, in other words, envelope following.  Is there a lot more to it that
> that?  Is the EF best done on the raw signal or the filtered signal?
> 
>> The PV-1 will not work (correctly) unless you have a good 
>> input signal.
> 
> 
> -- 
> Harry Bissell & Nora Abdullah 4eva
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