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the evolution of Gps
The Global Positioning System's satellites are now part of daily life

GPS technology is finally coming home. First developed for military purposes, its satellites are increasingly training their signals into homes, city streets and restaurants. Can't find your car in a parking lot? Need a quick Thai meal? Want to avoid a traffic bottleneck? Need to keep track of your pet? GPS is the solution. Answering such humdrum questions with an array of 24 satellites in space could never have been imagined before, and such evolution is now revolutionising the way we move, work and play.

When people say 'GPS,' they're usually referring to a GPS receiver that searches for signals from satellites that pass overhead. GPS stands for Global Positioning System, made up of 24 satellites (plus a few extra) that were launched by the American military and later thrown open for worldwide civilian use. The idea behind having satellites in space that could help navigation and positioning began to take shape in the 1960s, and such satellites were launched and tested for the military over the next three decades. By the mid-eighties they were made available for civilian use.

Of course, such earth shattering technology has been cooking a long time. Man has been looking at the heavens for centuries, trying to navigate his way across the world. Radio navigation was developed in the 1920s, where sea navigators would look for signals from shore-based transmitters. 40 years later, the first satellites were being rocketed into space.

How it works
How does it all work? The answer is as simple as it is space-age. Each satellite makes two rotations around the Earth every day, and there are at least four of them overhead you at any given point of time, wherever you might be. Each has an atomic clock, and beams out a signal with its data of time and position. When you switch on your GPS receiver on Earth, it receives this data-laden signal, and corresponds it to its own time and knowledge of the satellite's orbit. By measuring the time it takes for the signal to arrive, your receiver can calculate the distance between it and the satellite transmitter.
If you know you are 20km from satellite A in the sky, you could be anywhere on the surface of a huge, imaginary sphere with a 20km radius. If you also know you are 15km from satellite B, you can overlap the first sphere with another, larger sphere. The spheres intersect in a perfect circle. If you know the distance to a third satellite, you get a third sphere, which intersects with this circle at two points.

The Earth itself can act as a fourth sphere – only one of the two possible points will actually be on the surface of the planet, so you can eliminate the one in space. Receivers generally look to four or more satellites, however, to improve accuracy and provide precise altitude information.

Weaving through traffic
Till now, though, GPS systems were typically expensive, complex and heavy handed. You either had to have a luxury car to have one in your dashboard, or have to be a modern day Lawrence of Arabia, to include it in your caravan of equipment. Not any more. GPS units have become like cell phones (indeed, some phones even incorporate GPS receivers) – ranging from the cheap to the expensive. Costs usually revolve around colour screens, memory and build, but even the cheapest receiver – starting at RO30 – will tell you where you are.

The fun part is not even the technology, which is almost passé by now. The real deal clincher is using it in everyday life for the little things. While GPS receivers have already been incorporated into cars, their use has been largely traditional: look at your position on a digital map and navigate through streets. Further innovations are on their way – like customised live traffic reporting. Here, the system locates itself using GPS, then pulls down real-time traffic information through a subscribed satellite network. The device uses the data to route the driver around bottlenecks. This data can also come from built-in road sensors, or traffic police departments. Even more interesting is when drivers subscribe to a service where they share their GPS position with others on the road. This way, all subscribers see each other, and can avoid traffic jams this way.

Other uses include using the technology in place of tollbooths. If your GPS position shows up on a bridge that you have to pay to drive over, you can be billed for it without the need for a physical manned booth. As a side benefit, information collected can also be sued to monitor traffic patterns. Another novel use – although on the other side of the law – is when users keep track of where speed radars and cameras are placed. In some cases your instrument could even give a warning beep when you approach one.

Playing around
Since units have shrunk to the size of cell phones, anyone can carry, or wear them. Companies have already begun offering child monitoring services to parents, where kids would wear little GPS transmitters. Guardians can then see their wards appear on screens, or have an alarm go off when they leave a designated safe area, like the back yard or a safe beach when on holiday.

Even dogs are benefiting. Similar to the one for kids, this system can be attached to collars, and then owners can monitor movements on their receivers. If your pet leaves the yard, you'll get notification on your cell phone, PDA or any other two-way device. Software checks the pet's position constantly – when it passes the default boundaries, an automatic alert is triggered and owners receive a text message. It could say, 'Your pet has left' and then send the exact location. Locations will be identified by street name and number or, for certain phones, by maps. For both pets and kids, you would pay for the device plus a monthly monitoring fee. Another application of wireless technology may help reunite pets with their owners even when the animals are in another country. Implanted microchip transponders have been used for years in many countries to identify dogs, cats and other pets. The tags include a glass-encased microchip with a unique identification number that cannot be altered but can be read by a low-frequency radio scanner. The number is then matched to a database to find the pet's owner.

Humans at play can benefit too. Athletes have already begun using GPS enabled watches to keep track of their movements around a track, keying in track data and plotting their progress. Other players battle geo-ghosts who appear on screens whenever you're in their virtual location, and a lot of GPS devices today include geo games.

Hardware
It's not just people and animals that can be tracked. Transporters are including GPS devices in vehicles or containers that carry valuable cargo, so you can track your shipment across continents. Such systems offer tracking to a degree that no present courier can match – you will know the exact location of your shipment in real time.

Computer chip makers are working to build GPS capability into all sorts of chips – soon every new computer may know its own location, all the time. One result will be a new form of security in which sensitive files can be read only by computers at the right location.

A part of daily life
Of course, the downside of all this is the erosion of privacy, when people can see where each other are. Such connectivity also raises concerns over misuse and vulnerability. In the end, though, you will always have the freedom to disconnect, just as you have the ability to switch your cell phone off now. Some even say that GPS has brought about the demise of true exploration, when you can see the ends of the Earth on your screen.

Soon, GPS might go beyond global coverage. People are already thinking of reproducing the system with satellites orbiting the planet Mars, which could guide spaceships into space. In the emptiness of outer space, GPS waypoints will pop out of nowhere.

The real clincher will be the benefits reaped off such technology, which would far outweigh any negative side effects. Indeed, GPS is becoming such a part of daily life that it might lead to the death of the street address – why fiddle around names and numbers when you can have a virtual GPS waypoint? Every house, floor, street corner and mailbox could be a waypoint.

It is in such ways that an array of faraway satellites are burrowing their way into our daily lives. Whatever your orientation, they promise to change the way you relate to space and time, the culmination of centuries of theory, science and the innate human need to push the boundaries.