[ntp:questions] Can NTP sync within 1ms

Rob nomail at example.com
Sun Apr 27 18:02:07 UTC 2014


David Woolley <david at ex.djwhome.demon.invalid> wrote:
> On 27/04/14 17:28, Rob wrote:
>> We are setting up a co-channel diversity network.  That means multiple
>> FM transmitters that are transmitting the same signal on the same
>> frequency on different sites, where the receive areas partly overlap.
>
> This problem has already been solved using COFDM (aka DAB) and it is 
> much more tolerant of fading that is inevitable with co-channel 
> transmitters than your system.

It is not FM broadcast, it is (NB)FM communication.

>> The listeners should enjoy a smooth reception while driving around.
>> So of course there should be no time lag between the modulation signals
>> of the different transmitters.  Experts in the field tell us we should
>> be within 12us.
>
> Your transmitters will have to be contained within a circle of 3.6km, 
> reduced by the timing errors in the modulation at 0.3km/microsecond.

This turns out to be not the case.  Networks like this have been operating
for decades, only those were constructed using analog leased lines so
there was no relation to ntp, soundcards etc.



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