[ntp:questions] Can NTP sync within 1ms

William Unruh unruh at invalid.ca
Mon Apr 28 17:14:12 UTC 2014


On 2014-04-28, David Woolley <david at ex.djwhome.demon.invalid> wrote:
> On 28/04/14 16:19, William Unruh wrote:
>> For voice, the max frequency is something like 4KHz (eg telephone
>> quality) which is 250us (125us sampling) .
>
> Telephone quality is 3.1 kHz bandwidth from 300Hz to 3.4kHz, which 
> allows for channel filters/realisable anti-aliasing filters.

Not sure why they would need a lower cutoff, except that it would allow
the ancient telephone receivers to comply. Certainly one can make
cheap receivers now that go a lot lower than 300Hz.

>
> I believe that proper NBFM signals should have a 2.8kHz cut off.



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