GPS Overview Part 5 - Competitors
The original theory behind Location-Based Services -
or LBS - is to help you find out where you are or where something
else is.
One part of LBS is the GPS satellite
constellation. The following overview describes the history and workings
of GPS, as well as its uses and the future for it.
As it stands at the moment there are two satellite
systems being marketed as current and future satellite systems billed as
being able to provide location-based services.
GLONASS is the Russian Federation's
satellite navigation system. In many ways it is very similar to GPS: there
are 24 satellites in the full constellation; each satellite transmits
various data on two L-band carriers; there is one navigation signal that
has been authorised for civilian use, and further navigation signals that
have been reserved solely for Russian military use; there is a ground
segment that monitors and control the satellites; and users passively
receive its signals and are able to navigate with accuracy's of few tens
of metres or better.
However, it is too easy from a
user's perspective to presume that GLONASS is the same as GPS. Rather,
there are some key differences between the two systems. In many ways,
GLONASS is a more elegant and economical system design than GPS.
Unfortunately there are a number of quality control issues and much more
serious funding problems. The GLONASS system was declared fully
operational on 18 January 1996. Since then there have been few occasions
when the full complement of 24 satellites was operating. In addition to
satellite outages eight satellites have been withdrawn from service since
this date. So by late 1997 only 15 satellites were available for
navigation.
Thankfully though, recent
announcements by Russian officials may mean that 6 years of neglect of the
GLONASS constellation of satellites will stop. Solid government
financial commitments have been obtained to return the system to fully
operational status by 2006, Russian officials say. Also, this new
generation of GLONASS satellites (Glonass-M) will have longer in-orbit
lives that should ease pressure on the system, they said. They are
designed to have a seven-year service life, compared to three years for
the current GLONASS. Whether this financial commitment will materialise is
another thing, but even in its current weakened state, GLONASS still has
potential as a stand-alone navigation system, and as an augmentation to
GPS.
The Galileo satellite
radio navigation system is an initiative launched by the European Union
and the European Space Agency (ESA).The project architects plan deployment
in 2006-7, becoming operational in 2008 at a yearly cost of €220m. It is
projected by 2008 a constellation of 30 satellites should be
available.The technology behind Galileo is designed to be more accurate
and more reliable than GPS or GLONASS. This will allow safety-critical
systems - such as air traffic control, and ship and car navigation - to be
run on the technology. The system should also guarantee coverage to
previously inaccessible areas such as those that are either blocked by
buildings or isolated areas at high latitudes.
However it is estimated that the Galileo project could cost more
than €3bn ($2.6bn). With some of the member countries facing recession,
now might not be the time to fund the idea. Britain and the Netherlands
have already questioned the timing, and Germany has raised issues over
costs. In contrast, France and Italy whose aerospace industries both stand
to benefit from the system are looking forward to a go-ahead. The decision
to push ahead with the project remains up in the air for now.
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