What is
Global
Positioning
Systems
Satellites transmit signals to equipment on the ground. GPS receivers passively receive satellite signals; they do not transmit. GPS receivers require being in direct view of the sky, so they are used only outdoors. There are about 24 GPS satellites operational at all times, these are military satellites. In order for the GPS to know where you are it requires 3 satellites to triangulate your location. The accuracy of a position determined with GPS depends on the type of receiver. Most hand-held GPS units have about 10-20 meter accuracy.
Different types of GPS systems
There are many different types of GPS systems that you can get from:
1. PDA based GPS
2. Dedicated in car GPS
3. Mobile Phone based GPS
4. Outdoor GPS
PDA based GPS systems incorporate popular handheld computers and add the functionality of satellite navigation. The car kit is an essential part to these kits, the reason being they power the PDA and dependant on the receiver they link the receiver to the PDA. On cabled systems you require the car kit. Please note that you also require a memory card for 99% of these packages. The reason for the memory card is you need to store the map data and its not always possible to put the map data onto the PDAs internal memory. A good example of this is your standard PDA comes with about 32-128MB internal memory and the UK itself on most GPS packages is 128MB. There are many different types of PDAs and GPS receivers that you can package together.
Dedicated in car GPS, these types of systems are more suited for customers that only want the fastest satellite navigation and nothing else. These are normally the most easy to use and normally ready as soon as you open the box. There are now a lot of manufactures competing in this market making a lot of choice and cheaper prices.
Advantages of Dedicated in car GPS
Faster than you standard PDA based systems.
More reliable only doing one task less need to reset the unit.
Some offer large disk space from 256MB - 11GiG+
Less clutter more compact unit
Mobile Phone based GPS Technology of mobile phones is changing constantly, due to this you can now get satellite navigation on your mobile phone. Your phone can now navigate you around the country, ideal for people who dont like carrying a lot of gadgets about. Your mobile phone has to connect to a Bluetooth GPS receiver to get the data form the satellites. Make sure your phone is compatible as all the manufactures support different phones. For more information click on the images below.
Advantages Mobile Phone based GPS
Small dependant on the phone
Less gadgets to carry around
Less clutter only need to charge the PDA and GPS when required
TMC via GPRS easy to setup.
Outdoor GPS, these systems can be essential to walkers, sailors, pilots etc. These systems can give its user the required information from coordinates, waypoints etc. A good example of this is the SporTrak it gives you a compact, lightweight and includes bracket for fixing to boats. Combine that with Memory Map 2003 software to get OS Landranger 1:50,0000 maps available for whole of Britain. For more information click on the images below.
Advantages of outdoor GPS
Ideal for walkers, sailors, pilots
Know your location or coordinates wherever you are, can be a live safer
These are designed to be used outside more robust than your stand GPS more compact unit
Use certain GPS systems with Memory Map Software and plan your walk, sailing routes on 2D/3D maps
FAQ
Does the GPS receiver have to be outside the car?
This is a very common question, it really all depends on what car you have. Most recent models of cars are being fitted with heat reflective windscreens, this causes problems for GPS systems as it can cause the GPS signal to be lost. This is due to very very small wires running through the glass this then stops the signal from the satalites going to the receiver.
It can be cured by using a Reradiating antenna, which can be found
http://www.totalpda.co.uk/product4481_0.aspx
Information
Give your GPS signal a boost by installing this product on the outside of your car. The RA-45 reradiating antenna increases your GPS signal. If you drive a car that has a heat reflective windscreen then this product is essential for the operation of your Satellite Navigation System.
You simply place the antenna at a point in your car where a signal can be received, then trail the cable so it is close to your original GPS receiver. It needs to be powered from your 12V accessory socket, but is carries a pass-through connector so you can have two devices powered at the same time.
What receivers are available?
You can get all different types of GPS receiver from:
Cabled receivers
Sleeve based receivers
IR enabled receivers
Bluetooth enabled receivers
Can i go off road with my GPS?
Yes your GPS receiver will work anywhere it is the map data that you would require. Most of the civilian based systems are designed for road use. You can however get different software and map data to cover everything from off road maps, marine and aviation.
What is NMEA?
NMEA stands for National Marine Electronics Association
National Maritime Electronic Association. The NMEA 0183 standard for interfacing marine electronic devices is a voluntary industry standard, first released in March of 1983
What is meant by TTFF?
TTFF simply means Time To First Fix
This is the time it take for the receiver to obtain a satellite position from at least three satellites. Most receivers will work allot better if they get four more as if you loose one satellite you still have a fix with at least three.
Beginners Guide GPS 
Linear Mode
