GPS receivers may take Y2K-like hit

The GPS — or Global Positioning System — 24-satellite array
encircling the globe will not be affected by Y2K-related glitches, but
some ground receivers that process the signals from these satellites may
not function properly after Aug. 21, say government and military
sources.

According to press releases and information published by the federal
agencies and the military, the GPS system will “roll over from week
1,023 to week 0000 UTC or GMT,” causing many ground receivers produced
before 1994 to process signals incorrectly. The glitch could cause
receivers to display inaccurate positions, times or dates, or may cause
them to completely fail, according to the U.S. Information Agency
(USIA).

“Officials said that reports appearing in a number of countries
claiming that the system will cease to function at the time of the
rollover are in error,” the USIA said. “However, they urged GPS users
with older receivers … to check with manufacturers to assure that
their equipment will correctly deal with the rollover.

The GPS system was designed to work on a cycle of 1,024 weeks, or
about 20 years. The first cycle began Jan. 6, 1980 when the system was
launched, and Aug. 21 marks the end of the cycle. It is the first
rollover of the GPS system.

According to technical data, the problem stems from erasable
programmable read-only memory chips installed in GPS receivers. Older
chips may not be able to process the rollover changes and hence will
have to be replaced, though in some cases, “it may be easier and cheaper
to purchase a new receiver than to repair the old,” said the USIA.

Widely used in military, commercial and civilian applications, GPS
systems rely on a precise timing source (clock) to perform their
calculations. This aspect of GPS receivers allows them to generate both
relative and absolute time, according to a technical report
released by the FCC.

“Fast digital networks use an external clock to enable synchronous
data transmission,” the report said. “For some data transmission
systems, GPS based timing systems are used to provide the necessary
timing information” — a function that could cease to work properly if
faulty data processing chips are not replaced.

Calculating exact locations via GPS takes place in three stages. The
24-satellite array, called the GPS Operational Constellation, transmits
data to receivers located on earth. The second stage consists of the
Control Segment, which is a worldwide system of ground stations used to
process the information received from satellites. The third stage, or
the User Segment, are the actual GPS receivers located on vehicles, as
hand held portable equipment, or as stationary ground equipment.

Robert Cannon, a spokesman for the FCC, was vague when WorldNetDaily
asked by e-mail if the problem with personal GPS receivers was likely to
be addressed before the rollover date.

“Only the owners of equipment can assure its readiness and it is up
to each individual owner to thoroughly prepare their systems,” he
replied, referring all other questions to the U.S. Coast Guard. “They
seem to be leading the effort on GPS.”

In fact, the latest USCG memo on GPS systems warns that “users of the
Global Positioning System (GPS) should contact the manufacturers of
their receivers before Aug. 19 to determine if their systems could
malfunction beginning on that date due to conditions related to
“End-of-Week” (EOW) rollover.” That release was published Aug. 12, 1999.

Furthermore, the GPS Joint Program Office, which is managed by the
USCG, confirmed that all military applications endemic to GPS were
“unaffected by the Year 2000 (Y2K) and GPS End of Week (EOW) Rollover
Issues.”

However, a USCG report said, “Civil GPS users may need to verify that
their receivers and applications will work properly through these
events.”

The report said in essence, the “rollover problem is really a problem
that occurs every 20 years,” suggesting that it was a problem unrelated
to Y2K. The Coast Guard, nonetheless, has compiled a list
of GPS receiver manufacturers so civilian users could inquire about
potential problems and possible repairs.

In late July, the Air Force reportedly conducted Y2K compliance tests
on one of the 24-satellite GPS constellation, but no one could be
reached to verify if the tests were successful. A report
on the proposed
tests was published in mid-July, however, and said the Air Force had
already successfully tested all Block II and Block IIA satellites. The
units to be tested at the end of July were Block IIRs, but the report
did not say how many of each type of satellite the U.S. has deployed.

To this end, the Department of Defense has also been involved in
testing
certain receivers and has plans to continue testing until the EOW date.