[time-nuts] Another "atomic" clock question
GandalfG8 at aol.com
GandalfG8 at aol.com
Sun Mar 2 12:27:02 EST 2014
In a message dated 02/03/2014 16:06:49 GMT Standard Time,
bob91343 at yahoo.com writes:
Yes Nigel, it's a waste of time but so are computer games and going to
Disneyland and such. We do it because we get pleasure, and nobody can
I'm not sure where the waste of time comes in, that's certainly not
something I was suggesting, although perhaps not quite so convinced when it comes
to computer games and/or Disneyland:-)
It might become time consuming, even to the point of becoming an obsession,
but that still doesn't stop it being a very rewarding obsession:-)
I'm sorry, I had assumed you would at least be somewhat familiar with what
I was referring to.
Trimble made a GPS disciplined oscillator called the "Thunderbolt", that
was a reference to a comment in a previous reply, available on the surplus
market but now more expensive than they used to be.
The other unit I mentioned was what I considered to be a reasonably priced
Trimble are just one manufacturer of such items, it's also possible to
build your own, so some searches on GSP disciplined or conditioned
oscillators, GPSDOs for short, might indeed be very worthwhile.
Basically, what they do is correct the drift of a local oscillator,
usually contained within that unit and often 10MHz but not necessarily so,
against the frequency references used by the GPS satellites, and this gives you
your standard signal, so as well as the unit itself you need a GPS antenna
to receive the satellite signals.
There's a variety of factors that will affect resolution and stability but
1 part ber billion should be straightforward plug 'n go, and I would expect
a few parts in 10^10 with very little effort.
Because of the way this works the GPS reference itself doesn't need any
additional calibration, so if you did eventually decide to go for a rubidium
oscillator, as you suggested you might, this could be one way of
I am a bit confused over your mention of Trimble units. I'm not familiar
with them or what they are supposed to do. I better do some homework.
I know if I use an X-Y 'scope with two reasonably clean signals I can
adjust one for a stable pattern and so, depending on how long it holds still,
know how close the two frequencies are. I can get one signal from my
counter time base, but where do I get the standard signal?
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