[time-nuts] V standards

[Bruce Griffiths]

Poul-Henning Kamp wrote:
> In message <bef.38541c00.36663b55 at aol.com>, SAIDJACK at aol.com writes:
>
>   
>> Coarsedac changes are an issue as you mentioned, but one can get around  them 
>> by scaling the two dacs in a way to only use a couple of bits from the  
>> coarsedac, and operate most of the time using just the fine dac.
>>     
>
> If you are controlling this with a microcontroller, there is an alternative
> you should consider:
>
> Use only a single DAC and then PWM modulate its output, followed
> by a low-pass filter.
>
>   
The trouble with this approach is the very long filter time constants
with  24 bit PWM.
Combining 2 16 bit PWM outputs requires relatively close tolerance
components.
A synchronous filter is far more effective.

Bruce