[sdiy] How DCOs work

[Andrew Simper]

ADC -> DAC

On 12 October 2016 at 12:16, Andrew Simper <andy at cytomic.com> wrote:
> On 12 October 2016 at 09:24, David G Dixon <dixon at mail.ubc.ca> wrote:
>>
>> It seems to me (and, bear in mind that I know nothing about DCOs) that one could use a standard VCO circuit to control the current to an integrator, and use a digital circuit for the reset.  In this way, the only "tracking error" would be a slight loss of amplitude at high frequencies, and FM would still distort the slope.
>>
>> What am I missing?
>>
>
> You could actually use this to generate some cool "sync" type sounds
> with a "single" oscillator, apply a voltage to the pitch of the VCO
> for FM and then it will re-sync at the correct pitch :)
>
> Otherwise, if you are outputting the control current (or voltage that
> gets converted to the control current) digitally then you would need
> to have a digital accumulator to get the FM re-sync in roughly the
> right position. If you're already doing this with an ADC with enough
> resolution I would ask why bother with the VCO, you could just output
> the sawtooth waveform directly!
>
> Andy