GPS and Satellite Navigation

What is GPS?
GPS stands for Global Positioning System and is a system that uses satellites above the Earth's atmosphere as a means of pin-pointing the location of a GPS receiver anywhere in the world.

The Global Positioning System (GPS) is designed on the mathematical principle of Trilateration which allows the GPS receiver to locate four or more of the satellites in orbit and calculates the distance between each of them; which in turn allows the receiver to calculate its own location below. Global Positioning Satellites (GPS) use atomic clocks whilst the GPS receiver uses an ordinary quartz clock the likes of which you would find in an alarm clock or a digital watch.

Using GPS
You may find that you are already using the Global Positioning System already (GPS) without actually realising it. This is because most of the mobile telephones available on the market today already incorporate some kind of GPS system. Indeed some mobile telephones and PDAs (Personal Digital Assistant) have built in satellite navigation software that allows you to pinpoint your location without having expensive equipment fitted to your vehicle.

When you are outdoors be it travelling by vehicle or by foot it is useful to have such satellite navigation equipment in order to (a): track your location and map out the best route and (b): to enable others to help pinpoint your location should you become stranded in conditions which are less than favourable such as blizzards, severe fog or floods.

The Global Positioning System (GPS) works anywhere in the world and so it is useful for those individuals who might endeavour to climb mountains or go into thick terrain where they may become lost, disorientated or injured.

GPS and Vehicles
Many vehicles use a system called 'low-jacking'; 'low-jacking' is when a vehicle is factory fitted or fitted after purchase with a transmitter than constantly sends out its location to a central control point where it is monitored and logged. This 'Low-jacking' facility not only helps to combat the theft of vehicles but also helps to log their location if they are left unmoved for long periods of time. This in itself is useful if you were to go on an outdoor excursion and become lost or disorientated. Those individuals monitoring your vehicle's signal would be able to identify your location and whether or not you were stranded.

Walking and Hiking
Many individuals like to mountain climb or hike up the sides of mountains and extremely rocky areas. With this in mind it is always useful to carry your mobile telephone with you. Not only can your telephone send out a signal that can be traced through the Global Positioning System (GPS) but it can also be traced without such a system. A mobile telephone will send a signal that is relayed from one mast to another and emergency services can trace at least to the last mast from which a signal 'bounced'.

Again if you are walking across moors or land which may become quickly water logged it is important to carry such equipment with you if you have it in order to send out your location and also to communicate with the emergency services if possible.

You should leave details of your mobile telephone and its receiver number before you set off so that if you do fall into any difficulty the emergency services can track it more easily

Thanks to http://www.thesurvivalexpert.co.uk/gps-and-satellite-navigation.html