[time-nuts] GPSDO using 100Hz
warrensjmail-one at yahoo.com
Mon Nov 24 18:27:56 UTC 2008
Neither do I, know how to reply to a post that is. This may be the blind leading the blind
and end up in some unknown place.
True it would be simpler to use the High freq Osc directly but it would not be accurate.
The problem with just using the High freq as you suggested is that it is not at any known, exact or even constant frequency.
The divider number can change for each low freq cycle. Example if the master freq was say 0.2520 Hz high then
every forth second the divider would add 1 extra divide count and every 500th second it would divide by an additional extra clock time,
therefore skipping 11 divides every 500 seconds.
----- Original Message -----
From: "Mike Monett" <XDE-L2G3 at myamail.com>
To: <time-nuts at febo.com>
Sent: Monday, November 24, 2008 9:02 AM
Subject: Re: [time-nuts] GPSDO using 100Hz
> Sorry, I don't know how to reply to a post using the digest. But my
> question is if 100Hz or 10KHz are available from a GPS unit, where do they
> come from? Does that mean there is a 10MHz oscillator somewhere on the pcb
> that is just divided down?
> If so, then adding another PLL loop to control an external 10MHz crystal
> will just add additional noise, jitter, variable phase offset, etc.
> If there is already a 10MHz oscillator, wouldn't it be simpler to add a
> buffer like paralleled sections of a 74AC04 to the source, and drive a 50
> ohm coax directly?
> Mike Monett
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