[ntp:questions] Can NTP sync within 12us for NBFM

David Woolley david at ex.djwhome.demon.invalid
Tue Apr 29 06:47:34 UTC 2014


On 29/04/14 03:59, Brian Inglis wrote:
> I understand that the NBFM
> transmitter starts with phase modulation then integrates, multiplies,
> and filters
> the result to the FM carrier frequency

You are confusing carrier phase and audio phase.

(FM modulation is mathematically the same as frequency modulation except 
for the frequency response of the audio.  Both direct frequency 
modulation and phase modulation can be used.  I believe NBFM is 
pre-emphasised such that, for most of the passband, it is actually more 
accurately described as phase modulation.)



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