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windshield test
Important notice to Roadmate users.
When your roadmate is installed in a vehicle you must perform a signal level check to insure that the windshield does
not contain anti glare or heating elements that will block the microwave signal required by your GPS receiver.
Use this method to check signal quality.
1- Install unit and place antenna in vertical position
2- Power up unit and operate for 5 minutes
(Assuming it has been initialized)
3- Press the OPTIONS key on pad
4- Select CONFIGURATION
5- Go down to DIAGNOSTICS
6- Select GPS STATUS
7- Observe the 5th column titled SNR, the numbers should be 100 to 500 if signal is not blocked
Open window and hold unit outside while observing signal numbers for improvement.
External antenna recommended for best performance
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GPS accuracy
GPS accuracy is a very complex issue and is controlled by numerous factors beyond a simple explanation.
some very obvious factors are..
1-Satellite geometry and signal level
2-satellite health issues
3-multipath distortion
4-atmospheric disturbances
5-blockage of the microwave signal.
foliage, buildings,car roof and human bodies will stop the microwave signal used by GPS receivers.
Accuracy may be improved to 3 meters by allowing WAAS co rrection to occur,
It has been found that time is required by the GPS receiver to process the WAAS signal and correct the atmospheric errors
in the system, a period of several minutes in a stationary position will provide this correction.
The rated 3 meter figure is a lofty goal for commercial receivers but it is possible to achieve.
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