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Mitsubishi 4WD Owners Club of Qld (Inc) |
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GPS - Part 2 |
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GPS-101 Part 2 (Which One for Me) At almost every club meeting I’ll get a question, like, “What’s the best GPS for Me?”, or, “What’s the pick of the GPS units out there at the moment?”. Well these are not simple questions and people are probably a bit disappointed by my response, which usually starts with, “Well that depends …”. GPS units have come a long way since I bought my first one about 10 years ago. What’s more, like most electronic gadgets, today you get a lot more ‘bang for your buck’ than you did yesterday. So the questions are what ‘bangs’ do you need or want and how many ‘bucks’ are you prepared to spend? Also, importantly, if you get all of the ‘bangs’ you want, are you going to be able to drive the thing? If you have a VCR at home that is still flashing “12:00”, then turn to the Kamper’s Kitchen article now! Oohh – was that a bit harsh? What I’m trying to say, is that these days, you can spend a lot of money on GPS units with features that you may not understand and may never use. You can also spend too little and end up with a basic unit with which you’ll have to work really hard for it to be of use to you at all. Let’s first look at what is inside a GPS Unit (not all GPS units have all of these things, and some have many more):
There are hundreds of GPS units on the market today each with their own combination of capabilities and features. On the Sunday that I started writing this article, there were advertisements for 27 different units in the paper and junk mail that arrived at my place. All of these units were street navigation units. You know, the ones where you type in the address of your planned destination and they work out the fastest, cheapest, or shortest way to get there and then give you verbal directions. The cheapest of these was only $298. Amazing! What was even more amazing is what other ‘bangs’ you could get on these units. Here’s a list of some of the items: MP3 player; JPEG viewer; Built-in red light camera, fixed speed camera; and school zone locations; i-Pod input; Bluetooth for hands-free mobile phone; 1.3Mp camera; currency converter; 20Gb Hard Drive; built in mobile phone mainly for mobile internet to get updates of maps, road closures etc, or sending location back to head office; and …. a remote control so that the passengers can drive it. I’m not going to discuss street navigation units this month, because they’re great at getting you to the start of a 4WD trip, but pretty hopeless as soon as you go off-road. See if you can get one to give you directions from Happy Valley to Kingfisher Bay via Lake McKenzie. Some of these devices are based on PDAs and provide full GPS functions as well. So, what are the features that are most useful for 4WDers? Here’s what I reckon: The receiver should be at least a 12 channel parallel receiver. This means that it can be tuned in to 12 satellites at the same time. Most units these days have this. My first unit was only an 8 channel serial unit. It may also be important to look at the sensitivity of the receiver. Most common receivers have a sensitivity that is fine for normal outdoor use however, some of the places that we go will challenge common receivers. Super sensitive receiver chips in GPS units, such as the Sirf Star III, will provide better performance in rainforests and canyons. It may be difficult to find out which chip set a GPS unit uses, but it’s worth asking. An external antenna connection will allow you to connect up an antenna on the roof or front of the car rather than inside. This will also help with the reception of the satellite signals. A screen that you can read, with backlighting for night time. This is where a PDA with a 3.5” screen is nice compared to the old 1.8” screens of more traditional GPS units. Datums and Coordinate systems to match the maps that you have. The datum is the reference grid on which maps are plotted. If you’re using a paper map, then you need to know what datum it has and set your GPS accordingly. The most common ones for Australia are Australian Geodetic 66, Australian Geodetic 84, or GDA 94 (GDA 94 and WGS 84 are practically the same so don't panic if your GPS does not have GDA 94). It is also important to be able to display the location in Latitude-Longitude as well as UTM (grid) coordinates. Be able to record a ‘breadcrumb’ trail of where you’ve been. These are called Tracks. The limiting factor on most GPSs is the amount of memory that it contains. This seems to be becoming less of a problem. But, it’s nice to be able to record 10,000 track points or more. If you’re on the move a fair bit, this will be 4 or 5 days of Tracks, but you can make 1,000 track points last a day if you need to. My first unit only had 768. This is particularly important when you are doing a reccy for a trip so that you can see where you went and what distance and time each piece of the trip was. The ability to store more than one Track is useful, for you to plot your planned path, while still recording your actual path. Be able to mark specific locations – so that you can go back there (to find those really tasty sabre-toothed tigers). These are called Waypoints. Most GPS units allow you to capture 500 or more Waypoints. This is usually plenty, especially if you upload and download to your PC regularly. Be able to plan a Route of waypoints to which you can navigate in order. Most GPS units will allow you to store 20+ Routes, with 30+ Waypoints each. This is useful to be able to give you a distance to destination and estimated time to destination displays. An alarm tone is useful to alert you if you’re approaching Waypoints (i.e. you need to make a turn), or a Proximity Waypoint (These are usually used more in boating, but can be useful for 4WDing – especially if you’re driving down the Beach at night to mark the location of Rocks, Creeks, etc. A PC interface is essential – so that you can download recorded tracks and waypoints and upload planned waypoints, tracks, and routes. Be able to run it on 12v so you don’t need to keep shovelling batteries into it. It is usually best to wire directly to the battery or your auxiliary battery, rather that use your Accessories circuit, otherwise every time you turn the ignition off, the GPS will revert to running on the internal batteries and drain them in no time. I’m not really going to discuss the ‘Bells & Whistles’, like Bluetooth connectivity for your mobile phone or a built in camera. Most people can work out if they need or would like these. The next article I’ll start to cover “Driving your GPS Unit” – or at least how I drive mine. Happy Navigating. Greg Conlon |
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