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Operation Manual IQ Motor+
Almost no time difference
for Satellite 2
Position A
Moreover there is a better chance to find 2 satellites at 90° near the horizon,
than to find 3 satellites at 90° to each other directly above your position.
Because the circumference area at the horizon is bigger than the vertical area above the position,
and because it is assumed that the satellites are about equally dispersed, there is a better chance to
find convenient satellites near to the horizon.
The GPS module will therefore prefer satellites near the horizon for the horizontal position finding.
The module will calculate all possible combinations of visible satellites and makes every second
an average of these combinations.
In order to perform the same with the vertical position, the receiver would need twice the calculation
power. Due to the fact however that automobiles and pedestrians normally need the horizontal position,
this complexity is economised and calculation of altitude is performed from the best combination and by
the average value of time. That is the explanation for the smallish accuracy and the slow follow behind
movement of the vertical position.
The GPS module of Flytec instruments makes no time filtering over the horizontal position, but at good
reception it performs a filtering of around 5 seconds in the vertical position.
The poorer the GPS satellite reception, the longer this time constant.
Satellite 2
Time difference
Satellite 1
Position B
Calotte
45°
Satellite 1
This circumference
area is bigger than
the area of the calotte
above
62
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