[time-nuts] Holdover, RTC for Pi as NTP GPS source

Bob kb8tq kb8tq at n1k.org
Thu Nov 2 23:31:19 UTC 2017


Hi

I believe you indeed have tied this back to a number of papers ….

Bob

> On Nov 2, 2017, at 5:45 PM, Leo Bodnar <leo at leobodnar.com> wrote:
> 
> This is, essentially, how modern delta-sigma DACs work while achieving 24-bit and higher precision using only a single bit converter internally and a lot of clever digital filtering.
> Multiple loops are what would be called "higher order" in delta-sigma parlance.
> Delta-sigma tech is not poor man's DAC - it has properties that other conversion methods can't achieve, e.g. noise shaping and trivial aliases rejection.
> I suspect delta-sigma body of knowledge can be applied almost wholesale to this seemingly silly oscillator concept. 
> Did I just repeat something trivial that has been discussed to death here before? 
> Leo
> 
>> From: Bob kb8tq <kb8tq at n1k.org>
>> Subject: Re: [time-nuts] Holdover, RTC for Pi as NTP GPS source
>> There’s no particular reason to stop at the 100:1 point. You can run multiple 
>> loops at the same time and get out to essentially any level of precision. The
>> only question is over what averaging interval the precision applies.
> 
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