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Article by
Dag Pike


THE GPS BUG

The Millennium Bug where computers may not recognise the year 2000 on their clocks has been well publicised even though solutions may not always be apparent. With computers being used more and more on yachts it could be important to ensure that any on-board system which relies on computers is Year 2000 compliant. However, there is also a much more immediate "bug" problem looming which concerns the GPS receivers now used for position fixing on the majority of yachts.

This GPS Bug is similar to the Millennium problem in that it concerns the clock used for operating the GPS. Back in 1980 when GPS was first being developed it didn't seem to be a problem that the GPS clock or to give it its accurate title, GPS System Time, was given a life cycle of a little under 20 years. 20 years can seem a long way ahead and with the rapid advance in electronic navigation technology, perhaps it was thought that GPS would be overtaken by a better system in that time.

So here we are stuck with a GPS system on a time cycle of just under 20 years and the date when the cycle expires in August 22nd 1999, just a few months away. When this date is reached, one of two things may happen to your GPS receiver. The best solution, and the one you hope will occur to your receiver, is that it will automatically add a new 20 year time period to the computing process and the GPS will continue to operate normally. All GPS receivers bought after 1993 should have the ability to make this time switch automatically so, with modern receivers, you should not have any problems with the GPS and you will not even notice the change.

Even if your GPS dates back to 1990 you should be lucky and not have any problems. By 1990, many GPS manufacturers were recognising the problems which would occur in 1999 and were re-programming the software to cope. However there is no obvious way you can check this through the receiver itself so you should go back to the manufacturer or the dealer you bought it from to check chether it will adapt to the time change.

For those adventurous navigators who spent a lot of money buying GPS receivers in the early days of the system, there are several possibilities. It is unlikely that any receivers brought before 1990 will be able to cope with the change automatically, but again check with the manufacturer or dealer. You may be able to persuade the receiver. Others may require modification to the software to encourage them to cope with change and some manufacturers may offer this if you return the receiver to them. Finally there will be some, mainly first generation receivers, which simply won't work at all.

If you are going to rely on your GPS then you should take early action to see whether your GPS is going to work after the 22nd August. Remember, the time change will affect both stand alone GPS receivers as well as those buried inside integrated chart plotters. The latter are relatively new on the market and most will be dated after 1990 so you should be OK with these, but in all cases, do check with the manufacturer. One easy solution to this GPS problem of course, is to go out and buy a new receiver. If you have one of the early units it could be time to donate it to the local museum and bring your navigation up to date with a new, much more capable GPS.

Don't think that 1999 will be the end of this time problem with GPS. There could be another timing crisis at the end of April 2005 because of changes introduced into the GPS after it was first developed, and then the next 20 year cycle will end in 2019 so the same problem will re-occur again, but hopefully by then the problem will be fully recognised and dealt with.