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Cellular forums Home > Archive > GPS > September 2007 > GPS Status definitions...
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GPS Status definitions...
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| I am trying to find technical information regarding the old Motorola
Oncore M12 GPS recevier.
Specifically, I am interested in the what the following general terms
mean:
1. Bad Geometry.
2. Bad Almanac.
3. Differential Fix.
I am trying to understand what the above terms would mean in respect
to GPS Track (heading). If any of the above terms was indicated by the
recevier, could I rely on GPS Track...?
Any assistance would be gratefully received.
Many thanks
Marcus.
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| Travel by GPS 2007-09-26, 10:33 am |
| pod wrote:
> I am interested in the what the following general terms
> mean:
>
> 1. Bad Geometry.
> 2. Bad Almanac.
> 3. Differential Fix.
Hi Pod,
Free GPS training on my web here
http://travelbygps.com/training.php
You can listen to the training on your computer, but several of the
training topics are for listening to while navigating in the field.
The audio files are in .mp3 format so you can transfer them to your
portable listening device. Again, the files are free but I do ask
that you subscribe to Travel By GPS (email) newsletter.
I hope this helps!
Enjoy!
- Doug
Owner, TravelByGPS.com
BTW - It's my voice on the audio if some of you are interested in
what I sound like.
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| Olaf Greck 2007-09-26, 3:33 pm |
| pod <marcus.d.pollard@googlemail.com> wrote:
>I am trying to find technical information regarding the old Motorola
>Oncore M12 GPS recevier.
>
>Specifically, I am interested in the what the following general terms
>mean:
>
>1. Bad Geometry.
Ideally you want to be in the centre and the satellites should be
located around you, that way your receiver can make the most accurate
calculation of the position.
Bad geometry would be for example when all usable satellite are on one
side only with a small spacial separation.
>2. Bad Almanac.
The almanac contains information about the currently is use
satellites, their expected location and how they move. If you receiver
was turned of for a long time this almanac data can become outdated
>3. Differential Fix.
You receiver calculates the position not only by data received from
the satellite but it uses a (ground based) radio station that is
transmitting correction data.
Because the physical location of this radio station is known the
calculated location of the station can be compared to the known
location and the difference is send as correction data to your
receiver.
>
>I am trying to understand what the above terms would mean in respect
>to GPS Track (heading). If any of the above terms was indicated by the
>recevier, could I rely on GPS Track...?
>1. Bad Geometry.
Limited accuracy
>2. Bad Almanac.
Affects startup of receiver, tends to be no problem when already
tracking.
>3. Differential Fix.
Better accuracy
>
>Any assistance would be gratefully received.
You are welcome
best regards
Olaf
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