GPS is a group of 24 satellites each orbiting the earth at around 11000 miles above the surface. Each Satellite circumnavigates every 12 hours. At all times at least four satellites will be in view at any given point on the globe. GPS has been fully operational since 1990. Since the scrambling on the civilian GPS channel accuracy has greatly increased. Road Angel has a 12 parallel channel GPS engine with a built in active antenna. As long as Road Angel can see a minimum of 3 satellites then an accurate position of the vehicle can be calculated. Road Angel checks its position every second and is able to work out accurately the speed of the vehicle. Road Angel can store up to 50,000 unique locations.

Road Angel constantly compares its position with the stored database. When nearing a stored location the unit gives an audible and visual alert.

Road Angel uses complex heading software so it alarms only in the direction the camera faces.

As with all GPS technology, when Road Angel is first powered it must acquire satellites to know its position. The first start is known as a cold start which can take up to 45 minutes to acquire the minimum three satellites for correct operation.

Thereafter, warm starts (when the unit has been switched off overnight) should take a matter of minutes and hot starts (same day) a few seconds. When the unit has acquired satellites the display will show speed.

If after this period of time the unit is still not showing speed, reposition the unit where it will have a better view of the sky. You can check to see how many satellites it has acquired by scrolling through to the 'sat' menu.

MOBILE LASER CAMERAS
Now probably the most popular method of mobile entrapment used by the Police in the UK.
Both the Road Angel Classic and the new Road Angel 2 have front and rear laser detection as standard as well as GPS....read more although optional external number plate mounted sensors can be daisy chained into the road angel also to provide extra coverage.