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29 Jun 2004 08:25
It is like something out of Knight Rider; you are driving along in a strange city, wondering how to find you hotel when your car’s voice suddenly interrupts: “turn left here, and then right at the next traffic light”. It is an idea to appeal to anyone who has tried to drive and negotiate a map at the same time.
A car that knows where you want to go and can give you directions, hopefully without screaming that you should have understood it meant right when it said left.
Well, technology has started to catch up to the Hollywood fantasy and cars with built-in satellite navigation systems have been available for some time.
Satellite navigation relies on the global positioning satellite (GPS) system, a set of satellites orbiting the Earth. A GPS receiver on the ground sends a signal to the satellites above, and by precisely calculating the time it takes to send and receive the signal to four different satellites, the exact position of the receiver on the ground can be calculated.
Of course, knowing your exact latitude and longitude on the surface of the Earth is only so much use; what you need is a map against which the system can compare your location, so that instead of telling you that you’re at 27 degrees, four minutes and 49 seconds south, it can tell you that you’re at the corner of Voortrekker Road and Kerk Straat.
In-car satellite navigation doesn’t just tell you where you are, it can plan a route to where you are going, and give directions along the way. In order to do this, it needs to know not only where you are, but which way you are travelling, and how fast. Many of the high-end in-car systems do not just use GPS data, but information from a compass and the car’s braking system to calculate your speed and direction. This also means that if you are out of contact with the GPS system for any time, for example, in a tunnel, the computer can still determine where you are.
In Europe systems have been developed that can communicate with traffic control centres, so that your car can tell you how to get to where you are going and how to avoid roadworks and traffic jams at the same time. Unfortunately, this level of technology is not yet available in South Africa, but the system is sophisticated enough that if you turn off the road to avoid traffic, the computer will immediately recalculate your route according to your new location.
GPS navigation systems have been around for private use for quite a while — the receivers are fairly common, you can buy one at Cape Union Mart for about R4 000. What has been more difficult to get your hands on is the electronic map data that is needed to translate latitude and longitude into an actual address. It is these maps that have delayed the introduction of the system in South Africa, there simply did not exist the kind of electronic map data at the level of detail required.
As Jan Lotter of BMW South Africa explained, most electronic maps available are not accurate enough for in-car navigation systems; most go only to the resolution of about 100m. An in-car navigation system requires data to the level of individual house addresses, which is far more detailed. BMW has been working with several companies to develop the data used by its in-car system, which includes information on the location of petrol stations, restaurants, local attractions and streets and highways. In the most part, developing this data entails driving down each street and manually entering information into the system, which gives an idea of how much work is involved.
Despite this work, digitised map data for South Africa is still pretty limited. Currently satellite navigation systems cover only the major cities and routes along national roads. Some systems include tourist areas such as the Kruger National Park and Sun City. The data is being constantly updated, and users can buy CDs and DVDs with newer information as it is released, but you shouldn’t expect a digital map of Putsonderwater to be available anytime soon. Updating the data is not cheap, and you can expect to pay about R1 000 for a new CD when it is released.
In-car navigation systems are available in most high-end cars and is an optional extra in many others. You can also get a system installed into a car you already own. The quality and sophistication of the system does vary according to the car you buy — the system available for a Volks- wagen Polo will not be as fancy as the one you can get in a Touareg 4x4. Expect to pay about R20 000.
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