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Many people have come up to me and asked, "What GPS should I buy?" First thing I ask them is, "What sort of application are you going to use your GPS for? (bush walking, 4WDing, sailing, motor boating, etc etc)

Below is my answer for the 4WDrivers. Its a list of what to look for and the reasons why.

Any comments or feedback? Feel free to send mail

brian

Must haves:

      12 channel - this is the latest in GPS technology and allows the GPS to receive and process information from up to 12 satellites concurrently. Most new units have this feature.

      Datums WGS84, AUS GEO 66/84  - You must have the ability to set your GPS to the same Datum as the map(s) you are using. Most Australian maps are published using the Australian Geodetic 66 Datum, some Australian Geodetic 84 and the newer ones from Auslig are GDA 94 ( note that GDA 94 and WGS 84 are practically the same so don't panic if your GPS does not have GDA 94).

      Lat and Long plus UTM (grid) - most topo maps are published using grids vs Latitude and Longitude. However some (eg Hema) are published with Lats and Longs only. Having the ability to display your current location, among other things, in both formats is essential.

      External aerial facility - for maximum performance, and the ability to maintain reception in heavy forest areas an external aerial is a must. It's a bit like using a portable transistor radio in car. add an aerial to that and reception improves dramatically.

      Beeper or alarm - There's enough going on in a 4WD without the continual need to keep looking at a GPS screen - kids fighting in the back, gauges to check, obstacles to look out for. A audible beeper will warn you when your approaching a location without the need to keep watching the screen. Safety issue - quite possibly.

      External power and indicator - saves having to replace those 'expensive' batteries. Make sure when you wire up your GPS it is NOT connected to the ignition or accessory circuits. If it is, when your turn off the engine and remove the keys, the GPS will switch over to the internally batteries typically without giving you any warning. Power drain is so small that it is unlikely to drain any automotive battery over a period of time.

Nice to haves:

      PC interface - entering Waypoints and other information can be tiresome using the standard small buttons and functions on most GPS units. Having the ability to use a full size keyboard not only decreases time but increases accuracy. There are many programs available for managing waypoints. Try here for some.

      Battery Life - 80% of that quoted - Most manufactures will quote battery life in ideal conditions, minimum contrast, no light on, beeper off, etc etc. Estimate real battery life at about 80% of that quoted in the glossy's.

      Capacities - Track log(s), Waypoints, Routes - generally the more the better, 500 waypoints, 20 routes and 1000 track points is a good start.

      Large display, buttons and suitable mounting bracket - this is really a safety issue. Make sure that the GPS can be located in a safe, viewable and usable position. Some have landscape and/or portrait display modes. I'll have some pictures soon of sample installations.

      Internal light - saves having to use the interior light of the car. Will cause higher battery drain if used, so maybe a unit will multiple brightness settings would be advantageous.