[sdiy] Hybrid (analog/digital) vocoder?

[Paul Perry]

My aim was to keep the carrier signal in the analog domain,
and push the frequency spectrum detection into the digital part,
and possibly construct the PWM control signals in the digital
zone also.
Optimistically, this would make feasible a MS20 filter style
vocoder, surely a Good Thing ;D

I don't deny that many very acceptable fully digital 
vocoders exist, of course.

paul perry Melbourne Australia

----- Original Message ----- 
From: "cheater cheater" 
The digital domain will be much better for level detection of lower
bands, and depending on how you realize it, the higher parts too. Of
course you would need a separate audio ADC for each vocoder band. But
one such chip is simpler than a whole level detector, and you can in
that case also use different metering algorithms, which can change the
character of the vocoder substantially. The signal can bypass the
metering block and stay analog this way; the vca's shouldn't be
difficult, simple multiplying DAC application.