[time-nuts] Getting my Rockwell D200 GPS to work
Don Lewis
dlewis6767 at austin.rr.com
Sat Jan 7 01:40:51 UTC 2012
Thanks, Hal.
Tomorrow, I will take it all outside again and leave it, ...I only left it
on the car for 5 minutes or so.
My only other 'GPS' experience is my new Garmin for the car, ...it comes up
almost instantly. Maybe I should take it apart! :-)
-Don
-------------------------------------------------------
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Hal Murray
Sent: Friday, January 06, 2012 7:29 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Getting my Rockwell D200 GPS to work
dlewis6767 at austin.rr.com said:
> The antenna is currently on a shelf above my workbench, ....there is a
> ceiling and an upstairs above it. Then the roof.
> Is it very critical to be outside in order to 'see' the sky?
> I did take it out once and set the antenna on my car roof, ....but still
no
> satellites.
How long did you leave it on your car?
There are two problems in this area.
One is being able to hear the satellites. There may not be enough signal at
your workbench. It depends upon how sensitive your receiver is. Most of my
newer GPS receivers work in my house. Older ones work less well.
The other problem is what frequency to listen to. The satellites broadcast
the orbit parameters. That lets a receiver calculate the frequency to
listen
on. (The Doppler correction is important.) In order to do that, you have
to
know the time. That's why there is a pin for the backup power to the clock.
Without knowing the time, the receiver has to do a brute force search which
takes a while.
I would put it in the best location you can easily get to and wait a while.
It may take 15 minutes or longer. I wouldn't get upset if it takes a half
hour.
Once you get it working outside, you can take it inside and see if it still
works.
If you unplug it without the backup battery you will have to start over
again.
You can also just let it run overnight and see if that works.
--
These are my opinions, not necessarily my employer's. I hate spam.
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