Millennium bug’s first bite?
By Roopinder Singh

YOU are cruising along the highway, while your children explore the outdoors trekking. Of course, you had the state-of-the-art technology to help you navigate, when suddenly there is a glitch. Your system is on the blink and you are lost. Your children, meanwhile, also have a problem guessing where on the earth they are.

You plan a rally in the Himalayas in which sophisticated navigational equipment would be used for the first time in India. Just as everything is falling into place, the logistics have been finalised; you find out that the very system you were relying upon to give your rallyists precise navigational assistance is under a cloud.

A techno-nightmare? Not quite. It became a reality last week. The effects, however, were not quite the Armageddon-like as had been feared. It was just a cyber hiccup that could have been much worse.

One of the most common navigational aids today is the increasingly popular satellite receiver that tells you where you are. It is to be found in most aircraft, ships, cars and even in the backpacks of hikers.

Originally designed for the US armed forces for guiding their missiles, the Global Positioning System (GPS) has wider applications now, just like the Internet. GPS is a satellite-based system that transmits signals to receiving equipment. It can be used to locate positions anywhere on the earth.

Operated by the U.S. Department of Defence, GPS provides continuous (24 hours a day), real-time, 3-dimensional positioning, navigation and timing worldwide. Any person with a GPS receiver can access the system, and it can be used for any application that requires location coordinates.

The Russian Federation has its Global Navigation Satellite System (GLONASS), which has much in common with GPS in terms of the satellite constellation, orbits, and signal structure. Both systems are owned and operated by their respective defence departments, and offer precise, global, and continuous position-fixing capabilities. Both transmit spread spectrum signals at two frequencies and have pledged to make a partial set of signals available for civil use without any user fees for the next 10 years, or more.

The signals for civilian use in both are intentionally degraded and are less precise than those for use by the military.

GPS is available in two basic forms: Standard Positioning Service (SPS) and Precise Positioning Service (PPS). SPS provides a horizontal position that is accurate to 100 m. PPS horizontal accuracy is 20 m.

GPS has successfully proven itself in classical navigation application, and in fact, in popular usage has become the de facto navigational system. Because the user does not communicate to the satellite, GPS serves an unlimited number of users.

The US Air Force launched the first GPS satellite in early 1978. There are now 24 satellites orbiting the earth at an altitude of about 10,900 miles. The high altitude ensures that the satellite orbits are stable, precise and predictable, and that the satellites’ motion through space is not affected by atmospheric drag. These 24 satellites make up a full GPS constellation.

On board each GPS satellite are four atomic clocks, only one of which is in use at a time. These highly accurate atomic clocks enable GPS to provide the most accurate timing system that exists. It enables distances to be calculated from the time signals take to travel across the network. The system is designed to maintain full operational capability even if two of the 24 satellites fail.

Why would something so reliable have a bug? The answer is simple. It had experienced a Y2K-like glitch Saturday last. The problem, known as the "end-of-week rollover," comes from the way the satellites keep track of time.

They determine time by counting the weeks since January 5, 1980. They count the number of weeks up to a maximum of 1,024 weeks (19 years, eight months). They then return to week zero and start all over. This is broadly similar to the kind of problems associated with the millennium bug or the Y2K problems as it is commonly called.

Though most of the sophisticated receivers manufactured in the past five years were equipped to handle the problem, some receivers did malfunction because they took the date when the satellite clock was reset as January 6, 1980.

Widespread disruption, which was feared would occur when this happened, did not take place, though emergency services were on an alert.

A Japanese company that manufactures car navigators, however, reported that it had received about 600 complaints from drivers who said that their route went blank or flashed up gibberish.

The sets were fixed soon thereafter and things were back to normal. Once the GPS systems have gone past the rollover period, no other problem is foreseen. So there is nothing for the rallyists to get worried on this score.

One of the reasons for the less-than-expected damage was the widespread information about possible glitches, as well as the fact that most of the sophisticated systems do not use only GPS for their navigational needs.

Thus while driving your car, all you had to do was also to be aware of your actual surroundings using the empirical data brought to you through devices that have been with you since you were born — your eyes and your ears. The marvellous analytical bio-electrical instrument — the brain, would process it. All your children had to do was to also keep a look out for real landmarks rather than virtual contours marked in their GPS systems. Nothing like the real thing!