thru zero VCO suggestion.

[mbartkow at ET.PUT.Poznan.PL]

Paul Maddox wrote:

> Dear all...
> 
>   Heres a daft idea, dont shoot me, it onvolves eproms and
> adc's....

[...]

Hi Paul,

this is almost exactly what I have proposed about two months ago
in the wavetable/Wiard waveform city thread: Thru-zero frequency 
modulation is easily realizable using a sawtooth VCO, two ADCs,
a digital arithmetic adder and an EPROM. My idea was to extend
the input section of the Wiard's module by summing the ADC's result
with another digitized signal, which modulates the phase pointer
to the wavetable. Rejecting the negative and positive "carry" flags
at the adder output may be considered as equivalent to phase wraping.
Phase unwraping (done through digitization of a saw wave) summing
and rewraping is perfectly what is required for a true thru-zero 
frequency modulation (or phase modulation which is equivalent).

As far as I understand, the point of this very thread is to do it
in purely analogue domain.

regards,

MB


--

Maciej Bartkowiak, PhD
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