Re: Stationary GPS's tracklogs inaccurate, Moving GPS's tracklogs seem accurate, why?
- From: Dale DePriest <Dale@xxxxxxxxxxxxxxxxxx>
- Date: Wed, 25 Jul 2007 11:58:48 -0700
PGPS wrote:
Hi,
I record the locations on my GPS (logging tracks). I observed that
these tracklogs are inaccurate when the car is stationary, but very
accurate when the car is in motion.
For ex: If I am driving on a road which has a lot of traffic lights,
the tracklogs show a straight line along the road, and a zig-zag lines
when I make a traffic stop.
Why is this so?
Thanks.
this is normal. As the satellites move around there is variation in the computed position. Generally this is a small movement but can vary 30 feet or so and in a few cases even further. The unit has no notion of direction when stopped and this variation will show up over time. Some people use this data to average a stopped position over time and it can even result in higher accuracy for that location. Some GPS devices actually pin the position when stopped to avoid displaying this data but that does not make them any more accurate.
Dale
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