GPS with Ordnance Survey mapping - FAQ's

Q. How do I set my handheld receiver so that the displayed coordinates are compatible with Ordnance Survey mapping?

A.  Your receiver will have a datums setting to change the coordinates inside the receiver to output OSGB36 national Grid coordinates. If you have problems, your first point of contact should be your receiver manufacturer.

Q. Why does my handheld GPS display a height of 40m when I know I'm at sea level?

A.  The model of the Earth's surface used by many handheld GPS receivers is often a mean fit for the entire world. Because of this the model may not fit Great Britain very well resulting in a height discrepancy. Height is always the least reliable element in a GPS position fix especially for a navigated position.

Q. Why has my handheld GPS receiver not got a position fix after having been running for 10 minutes?

A.  If your receiver is new or has not been used for some time it may take over 13 minutes to get an initial position fix. Your receiver uses an almanac containing information on the satellite constellation to search the sky for GPS satellites. If this almanac is out of date, it may take your receiver some time to lock on to an initial satellite and then a further 12.5 minutes for an updated version of the almanac to be transmitted to your receiver.