GPS Article in Sun-Sentinel : LUSENET : TimeBomb 2000 (Y2000) : One Thread

Here is an article concerning the coming rollover of the GPS system.

URL is here:,1136,22000000000105249,00.html

Story is here:

Y2K comes early for some GPS systems

By CHRISTINE WINTER, Staff Writer Web-posted: 6:12 p.m. Aug. 11, 1999

Boaters, pilots, new car owners and even hikers and campers may experience their own version of the Y2K bug later this month, when their older GPS (Global Positioning System) receivers could experience problems comparable to the computer glitches expected at the end of the year.

GPS is a navigational system which uses an electronic receiver to pinpoint a location anywhere in the world quickly and accurately by calculating the distance from overhead satellites. The problem, known as End of Week Rollover, or Week Number Rollover, refers to the way the GPS system measures time, and is related to a change in the date which may confuse computers in uers' receivers.

"End of Week Rollover is really 'the millennium issue' for GPS users," said Brian Gifford, a product support specialist with Raytheon Marine, Hudson, N.H., one of the leading manufacturers of the popular navigational tools. "It just coincidence that it is occuring four months prior to the Y2K problem."

"There are more units out there that will not be affected by the End of Week glitch than there are devices that will be affected, but there are still some units that were built as recently as the mid-1990s that are going to need a software fix to keep working," Gifford said.

He said Raytheon expects no problems, since it began building corrections into its devices as far back as 10 years ago.

The GPS system has its own way of measuring time, based on a 1,023-week clock, which began the week the system was activated by the Department of Defense, on Jan. 6, 1980. The system was created as a way of saving memory space on satellites. When that clock reaches week number 1,024, approximately every 20 years, it rolls over to zero and starts over. The first End of Week Rollover since the system began will occur at midnight on Aug. 21, 1999.

The Department of Defense has determined that the rollover to week zero will not cause a problem for either the satellites or the ground control centers. But older model receivers, usually pre-1994 models, could interpret the zero as an invalid date, or they may roll back to January, 1980, and process satellite data incorrectly.

Since compliance varies from manufacturer to manufacturer, there are no real estimates of how many of the older, non-compliant models still might be in use.

"We estimate that of the 2 million GPS receiver products we have shipped since 1989, maybe 30,000 of them were made prior to our correction for the End of Week Rollover," said Jim White, a spokesman for Magellan System Corp., San Dimas, Ca. "That is fewer than 1 percent of the Magellan products made, but if you have one of them, it is 100 percent for you."

Just as in the case of the change from year 1999 to year 2,000, no one is quite sure what kind of problems the rollover from week 1,023 to week zero will generate. But a variety of government agencies ranging from the Consumer Product Safety Commission to the U.S. Coast Guard are warning of these possible problems in non-compliant receivers:

It could appear to work, but display inaccurate positions, times or dates.

It may be unable to locate the satellites, resulting in no response at all.

It may take more time than usual to locate the satellites.

The once costly GPS technology, first developed for military use, has become more and more affordable in the last five years, and hand-held GPS receivers can often be purchased for under $300, making them popular not only with recreational boaters and pilots of small aircraft, but campers, hikers, fishermen and hunters. They are also being built into luxury models of new cars.

Some of the older non-compliant models require a software upgrade, and some can be fixed by simply clearing out the memory and reinitializing the device to update its time, date and approximate location from the satellite. The oldest models--those dating back nine or 10 years-- cannot be upgraded, said Magellan's White. He said his company is offering trade-ins on any such units that may still be in use.

The Federal Trade Commission, which is overseeing the multi-agency push to warn consumers, recommends that any owner of an older model GPS, call the manufacturer for advice on how to adapt it for both EOW and Y2K. You must have the receiver model, serial number, and software version or release date.

Some manufacturers, such as Trimble Navigation Ltd., Sunnyvale, Cal., have done extensive testing on all products for both EOW and Y2K compliance, and have posted the results on their websites. Trimble (, for example, lists each product as "compliant," "upgradable" and "noncompliant."

The Coast Guard Navigation Center's web site has a list of manufacturers and contacts ( for consumers to contact. You can also call the free federal Y2K consumer hotline (1-888-USA-4-Y2K) for manufacturer contacts.

Christine Winter can be reached at or 561-243-6601.

[[Just thought someone might be interested. I hope the catagory of "Technology" is the correct one.]]

-- J (, August 12, 1999

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