[time-nuts] Slight tune-up of rig

Magnus Danielson cfmd at bredband.net
Sat Jul 23 21:07:17 EDT 2005

From: "Tom Van Baak" <tvb at leapsecond.com>
Subject: Re: [time-nuts] Slight tune-up of rig
Date: Sat, 23 Jul 2005 17:41:38 -0700
Message-ID: <000d01c58fe8$74853a00$6d30f204 at computer>

> Magnus,


> Thanks for the Z3801A report. So far you're doing all the right things.

Thanks, Tom! That feels reassuring! ;O)

> There are some commands to force it to enter
> survey mode, which you'll want to enable so it
> doesn't operate in position hold mode at the old
> location. Read through your documentation and
> look for commands like:
>     :ptime:gpsystem:position:survey once

Did that (through SatStat). I also forced it into a more reasnoble position
using GPS:INIT:POS <a position in my general neighborhood as I created without
having looked at the map or another GPS>. It *is* picky about the formating
thought, however, I played a little bit clever and asked if for its last hold
position, which comes out in the right format and then only edit the numbers
around to be in my general neighborhood (several degrees of, but that doesn't
make much difference for the initial constalation subset).

I am currently tracking 4-6 satellites. I could have 10-11 in my view if I had
the channels and allowed lower elivation angle. I guess with another receiver
and another antenna maybe.

The receiver just completed position survey and went into position hold.
I currently have TFOM = 3 and FFOM = 1. I have valid PPS, but the SmartClock
feels that it needs to do some more homework, and I will certainly not get in
it's way! ;O)

>     :diag:gps:utc 1
>     :syst:preset

Didn't do these... but I don't seem to have to do them. To tired to read the
details out of the manual right now so what are they suppose to be doing?

> You may need to power cycle to get some of these to take hold. Or it could
> have already been taken care of for you by the previous owner.
> You may find it easier to use the Z3801A to make once a week or even once a
> month changes to your Rb rather than operating the Rb as some sort of
> continuously disciplined oscillator.

Once a week is continous too, just a very low update frequency. I am pondering
over having some TI counter setup together with a Kalman filter. Maybe also
some environmental measurements tossed in just for fun. Shouln't be too hard
to cook up.


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