So there is no point in substituting another GPS RX? What is the sawtooth
compensation is see mentioned? What about the antenna cable length
compensation? How much does that affect the AVAR?
Bob
----- Original Message -----
From: "Steve Rooke" <sar10...@gmail.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Thursday, June 24, 2010 11:11 AM
Subject: Re: [time-nuts] Substitute GPS in a Z3801A
Sorry to butt in on this thread but, although you need a number of
birds to get an accurate position, you really only need one to get
timing. If you have a six sat tracking receiver there should be enough
to give accurate time. You can always set the elevation to limit what
sats you can see so to screen out multipath reflections and it can
still track six birds. OK, my Z3805A is currently tracking 9 birds but
3 of those are quite low horizon, although I really don't have
anything to cause multipath from where I'm situated. The minimum
number of sats I track is 4 and the max is 12 on a day, night cycle
and the average is about 6.
Steve
On 25 June 2010 02:01, Robert Benward <rbenw...@verizon.net> wrote:
Mike,
Thanks for the info!. Does anyone know for sure if the timimg improves
with more satellites tracked? I don't know how they derive the 1PPS, is it
a blend or one satellite at a time? Maybe I will leave well enough alone.
Bob
----- Original Message ----- From: "Mike S" <mi...@flatsurface.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Thursday, June 24, 2010 9:01 AM
Subject: Re: [time-nuts] Substitute GPS in a Z3801A
At 10:48 PM 6/23/2010, Robert Benward wrote...
Has anyone ever put another GPS in a Z3801A? Will the software
accommodate
another GPS that tracks say, 12 channels?
Possibly 8 channels. You must use a Motorola Oncore VP. A 6 channel one
was what HP used. There are mixed reports on using an 8 channel VP -
some say it works fine, others say you must configure it in 6 channel
mode (but you do pick up improved reception). Whether the different
reports are due to changes in configuration or firmware of the z3801a,
the Oncore, or both - I have no idea.
The commands/responses used by the z3801a prevent it from working
directly with newer GPS modules, like the GTs, UTs or M12s (even if you
adapted them physically).
If you want to try and get better performance with a newer GPS
receiver, you should be able to leave the existing board in place, and
bypass the 1PPS input with the signal from the newer receiver. You'd
only get in trouble in exceptional conditions (new receiver loses sync,
but existing one is reporting good satellite lock, etc.). Of course,
the z3801a satellite reporting wouldn't be worth much.
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--
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
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