[ntp:questions] Re: Why phase modulation

Terje Mathisen terje.mathisen at hda.hydro.com
Mon Jan 9 14:43:47 UTC 2006


Rob van der Putten wrote:

> Hi there
> 
> 
> Why does DCF77's phase modulation (DCFp) offer a more reliable timing then
> AM?

Because the pseudo-random spread spectrum phase modulation works at much
higher frequencies than the 1 Hz AM timing pulses.

(Arguably, the PPS signals have very short rise times, which means that
they are actually relatively high frequency, but the phase modulation is
faster still.)

> Who produces these recievers and what do they cost?

Probably Meinberg.

> Is GPS better or cheaper then DCFp?

GPS is a little bit more precise, works globally, and can be _much_
cheaper, since you can use high-volume products like the Garmin PS18 LVC
which costs less than $100.

DCFp is a good backup to a set of GPS clocks though!

Terje

-- 
- <Terje.Mathisen at hda.hydro.com>
"almost all programming can be viewed as an exercise in caching"




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