[ntp:questions] Can NTP sync within 1ms

jimp at specsol.spam.sux.com jimp at specsol.spam.sux.com
Sun Apr 27 18:27:52 UTC 2014


Rob <nomail at example.com> wrote:
> 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.

Which makes all of this even more irrelvant as communications circuits
usually bandwidth limit to around 3.5 kHz.

>>> 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.

Just what part, given your original conditions, is not true about this?


-- 
Jim Pennino



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