GPS - What the fuck is it? Its not GPRS !

2006-03-10 11:15:49
I've been interested in GPS for a long time now – it offers the promise of never again having to allocate 45 minutes extra to my travelling time just in case I get lost.

In case you didn't already know, GPS stands for Global Positioning System, and it’s a system of 27 satellites (24 in operation and three extras in case one fails) orbiting the Earth that are used to tell you where you are in real time.

Because GPS for the average consumer is relatively unknown in this country, we’ve compiled a list of the most commonly asked questions and answers.

How does GPS work?
As mentioned before, GPS utilises a number of satellites put up by the US Department of Defence.

The system works by a simple mathemati-cal principle called trilateration.

Trilateration works by having the GPS receiver calculate your distance from a GPS satellite, by measuring the time that it takes for the satellite’s signal to reach you.

Knowing your distance from this satellite means that an imaginary circle can be drawn around the satellite, where your location is somewhere along the perimeter of this circle.

The GPS receiver also calculates your distance from a number of other satellites as well, and the resulting intersecting point of these circles will be your actual position.

The system requires at least three satellites to work, but ideally you need four or more to get a pretty good estimate of your position on Earth.

What do I need?
On the user side, all you need is a GPS receiver, which is a unit that takes information from various satellites and actually does the calculation that works out where you are.

GPS receivers come in a variety of different types from basic monochrome units to full-colour talking handhelds. Recently, Bluetooth units that are meant to work in tandem with Pocket PCs and PalmOS handheld computers have also appeared.

Knowing your latitude and longitude on Earth alone isn’t particularly useful, since we can’t do much with that information as it doesn’t show us roads, points of interest and anything else that we need as a reference point.

This is where a good GPS-capable map comes in.

Coupled with a good map of the area that has information about latitude and longitude embedded, a good GPS receiver can actually tell you where you are and even give you voice directions to any place that you define – just enter your destination and the GPS receiver will calculate the best way to get there and give you directions!

However, there are a few problems with using GPS in Malaysia – one of them is the price of GPS units that have always been a little out of reach for the average person, and another is the scarcity of any good Malaysian maps that will give you turn-by-turn voice directions.

Recently though, GPS receivers of all kinds have gotten a lot cheaper and more easily available (the HP iPAQ h6365 comes to mind as the most well-known). Proper Malaysian GPS-capable maps have also appeared.

Do I get charged for using the GPS?
The answer is no – the service itself is free, and you only have to pay for a GPS receiver to get you started.

However, there is a catch – while a GPS receiver at its most basic can work by recording “tracks”, i.e. it can create trails for places you’ve been to, it’s only really useful if you can load maps on it.

This is where a certain amount of cost comes in – to get the maps for your GPS receiver you’ll usually have to fork out some money and with Malaysian roads continuously changing, this could cost you quite a bit if you want to be up-to-the-minute with your maps.

Currently one of the local providers of Malaysian maps for GPS is Mappoint Asia

However, if you’re using a Garmin GPS receiver you’re in luck – there is a very active community of Garmin GPS users who constantly maintain and update GPS maps for most of Malaysia and Singapore. You can find them at

If you have a Pocket PC or PalmOS device, you need to get the application that will make use of the maps as well.

You can check out the FAQs at malsingmaps for help on what applications you can use.

Can the GPS unit tell me if there’s a traffic jam?
This is the second most common question and once again, the simple answer is no.

This is because GPS satellites are not spy satellites – they just send out one-way signals to indicate their position in space, and are NOT equipped with high-tech cameras that photograph and log traffic jams.

Therefore, at any given point in time, your GPS receiver is just calculating your position and not receiving any other information on where other vehicles or GPS units are.

Is it the same with Maxis GPRS ?
Its not ! Dont get confuse GPRS and GPS. GPRS is data transferd. General Packet Radio Service. A GSM data transmission technique that does not set up a continuous channel from a portable terminal for the transmission and reception of data, but transmits and receives data in packets. It makes very efficient use of available radio spectrum. While GPS is Global Positioning System.

- article from the Star + added a little by myself.