Once they were only for the rich and were only fitted in the very high end cars but today SatNav systems are available to all. You can either opt for the in-car fitted systems that are still quite expensive or you can go for the handheld or protable units. This article is about the latter.

What is SatNav?

SatNav is a system that comprises of 2 elements, a GPS data receiver and a CPU/display unit. The receiver gets information from orbiting GPS navigational satellites and communicates it to the CPU/display unit. This unit is then able to find its exact location on the planet by comparing signals from various satellites.

The unit incorporates road maps of the area and places an indicator on the map showing where the car is on the maps.

Features

The units allow you to plan a journey ahead of time and then the unit will guide you to you destination by displaying a map showing you where you are and the direction you should be heading. Most now have voice instructions so the unit will tell you, when you are approaching a junction, which turning you should take. The units are also capable of making real time adjustments to the route, this means that if you go the wrong way the until will recalculate the route to your destination taking into account the wrong turning you have just made.

Maps

The maps for the unit can be loaded for the different regions you visit, so they may have a map of the UK and another for France and so on. Most modern unit have the maps stored on a removable memory cards like SD cards or similar memory card but some units read directly from a CD or DVD. The display can be set to show the conventional flat map view or the new 3D view that shows a view as if it was above you and looking forward. This view is very good and clear.

Traffic

Some units offer systems that will warn you of road works/traffic jams etc as they happen, and offer suggestion as to how to avoid them.

POI

Most units have POI's (Points of Interest) incorporated into them that will show things like garages, restaurants, historic sites, airport and ferries etc. You can also add your own POI's of your favourite places. One POI that is very popular is the location of all the speed camera and accident black spot locations.

Weather

Another feature that is becoming increasingly available is the weather for a location. The system will tell you the weather at a certain location on the map i.e. at that beach location you are planning to visit.

When you want to plan a journey you will need to enter the start and end destination, this can be done in a number of ways, the city, street and house number. The street intersections, the post codes and a location chosen on the on screen map. The start can be done in the same way with the addition of the present location as the starting point (remember the unit knows where you are). There are then itinerary or way points, these allow you to program destinations along the way. Finally you are usually presented with choices of routes with choices like, Fastest Route, Shortest Route, Scenic Route, Avoid Motorways etc some have the choice to avoid toll charges.

Fitting

The units can be fitted into the car in a number of ways but the 2 most popular ways are with a mounting bracket that has a strong suction cup that sticks to the windscreen. The second way is a bracket that fixed to the cars air vents, this method can be very good but required a fixing for each type of car. The unit is then fitted to the brackets and adjusted to the best viewing angle.

There are dozens of systems available now with a variety of choices of the options available. You need to choose which of the above options are important to you and then choose the until that best suits you or suits you price range.

You can see a large variety of different units at different costs at my favourite comparason site www.wangled.co.uk just type in "Mobile GPS"

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Paul Davies is a professional engineer and product reviewer, he submits articles on product guides and reviews. All his articles can be seen on the premium shopping comparison site http://www.wangled.co.uk on the following page http://www.wangled.co.uk/buyersGuides.asp