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Richard Hammond

Vehicle & Alternative fuels news

The first GPS satellite was placed in orbit in 1978, with another 23 launched and positioned up to 1994. These satellites where originally for use by the US Department of Defence and transmit a very low power radio signal. This allowed anyone with a receiver to determine their location on Earth, whether they are on land, sea or in the air with an accuracy of between 5 to 10 metres under normal conditions.

The satellites are positioned in a geo-stationary orbit at about 12,000 miles above the earth and are arranged so that 4 are visible to any GPS receiver at any time. They are mainly powered by solar energy but also have battery backup facilities.

The GPS system works by receiving a signal from multiple satellites, usually 4, and calculates the time it takes the signal to reach the receiver multiplied by the speed of light, which gives the distance from the satellite to earth. It does this with each satellite, which it receives, and from this the receiver is able to work out its position on Earth. As long as the receiver can see three satellites then a position can be calculated.

Most GPS systems check their position every second and from this is accurately able to calculate the speed of the vehicle it is connected to. There are now however some GPS units which check there position every 0.1 seconds and offer a greater degree of accuracy.

Vehicle GPS systems which detect speed cameras or display information on static locations do so by checking their current location against a database of information stored within the device. GPS navigation systems work in the same way but compare their location against the route required.

GPS systems are now helping business users with things like their mileage which the GPS system will log and can then be downloaded to the users PC and imported into a spreadsheet. This helps keep track of mileage and expenses easily. The Road Pilot has been designed with business users in mind.

Performance GPS systems are now available which drivers and manufacturers use to evaluate performance and products. The race driver can now use a device called a Driftbox which keeps track of lap times, as well as variables such as acceleration, top speed and g-loading. These devices are accurate to 0.1 of a Km/h and check the GPS signal every 1/10th second. Manufacturers also use these devices to evaluate things such as tyres.

Even with GPS systems devices as small as wrist watches, anyone can now check their position, handy if you’re out walking, cycling or on a boat.

More information can be found here