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Global Navigation Satellite System
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The Global Navigation Satellite System is being used for a variety of
diverse purposes including rescue, military, transport, etc. While
majority of people in Pakistan, especially those in Northern areas, may
not know anything about this technology, they are very painfully aware
of its lethal potential. The drone attacks are a case in point. These
harbingers of death are operated from thousands of miles away
through satellites and are capable of delivering their lethal cargo to
their unsuspecting targets with surgical precision. However, the
peaceful applications of this technology are also immense and varied.
Sana Aijaz explores the various aspects of GNSS
Global Navigation Satellite System (GNSS) is a revolutionary navigation
technology in the field of communication, navigation and surveillance. A GNSS
estimates the location of fixed and moving objects on the ground, in the
atmosphere and in space using precise timing and geometric triangulation.
GNSS satellites provide accurate three-dimensional positioning to anyone with
the appropriate radio reception and processing equipment. Typically, the
architecture comprises three subsystems: a satellite constellation (space
segment), a ground segment to control and monitor the space segment and
end-user mobile receivers. These subsystems can in turn be enhanced
through space- or ground-based augmentation.
The only fully operational capable system in existence at the moment is the US
Navstar Global Positioning System (GPS). However, the Russian GLONASS is
being developed towards full global coverage. The People's Republic of China
is in the process of expanding its regional Beidou Navigation System into the
Global Compass Navigation system by 2020. The European Union's Galileo
Positioning System is a GNSS in initial deployment phase, scheduled to be
fully operation by 2020 at the earliest.
The existing Global Navigation Satellite Systems have important military
applications. Today, most military platforms used by the US military and its
allies benefit from or can be fitted with a GNSS receiver. Besides military
platforms, supplies and equipment can be tracked to improve logistics.
Through the use of a transmission element, positioning services can also be
used to track enemy assets and positions.
The capability to synchronize the movement of different units on the battlefield
– from space, air, sea and land – provides the current and future field
commander with unprecedented area awareness. Combined with the accurate
weapons guidance provided by GNSS, there is improved strike effectiveness
that may minimize the amount of collateral damage caused during an
operation. The possibility to strike from a distance reduces risks to military
personnel involved in operations. The use of navigation and positioning
technology may also reduce the risk of accidents due to ‘friendly fire’.
Besides military requirements, GNSS offer a multitude of commercial
applications. The growth of the transport sector, the fast evolution of
telecommunications, and the development of other services requiring
positioning – such as rescue services – reinforce the notion of GNSS as a
multiple-use technology.
Signal transmissions are an integral component of aviation, shipping,
telephony, computer networks and many other areas. Positioning plays an
important role in these fields since it enhances economic efficiency. For
example, in aviation, savings may be accrued through more direct aircraft
flights (attained through improved traffic management), more efficient ground
control, improved use of airspace capacity and fewer flight delays. GPS is
already an important tool for in-flight safety through its provision of en-route
navigation, airport approach, landing and ground guidance. Similarly, road
applications using GPS technology, presently gaining attention include in-car
navigation, fleet management of taxis and driver assistance.
In the energy sector, timing and positioning systems can be used to optimize
the transfer of electricity along power grids and lines. Increased drilling safety
brings benefits to the gas and oil sector. For the banking sector, useful
applications range from the creation of legally traceable data stamps (for the
reduction of false transactions) to the synchronization of financial operations.
From an insurance perspective, GNSS may be used to monitor or trace the
transport of valuable goods. GNSS already plays an important role in
emergency services such as search and rescue, disaster relief and
environmental monitoring. Current emergency beacons operate with the
Cospas-Sarsat satellite system. In addition to the professional applications,
individuals are discovering the recreational uses offered by GNSS.
Commercial GPS handsets are increasingly commonplace for trekking, sea
navigation, etc. However, with no real-time service guarantee and inaccurate
estimates (provided in kilometers), there is room for improvement.
GNSS has its limitations despite its military and commercial advantages. There
are three frequently referenced shortcomings. First, positioning signals tend to
be less precise in urban environments or under foliage, in areas where the
number of satellites in-sight are low (typically at upper and lower latitudes
around the poles), and under certain weather conditions such as thick cloud.
Second, GNSS services may suffer from intermittent service coverage. Given
the limited lifespan of the space component, the system needs to be
replenished and/or reconfigured periodically. For example, during certain
upgrading operations, receivers relying on information from ground stations or
satellites being manipulated may be affected. Even if the service is degraded
for a couple of seconds or minutes, the impact may be significant (e.g. air
traffic). Finally, as a vital component for a growing number of commercial and
military applications, global navigation and positioning systems may be
vulnerable to attack by hostile entities. For example, a ground station may be
physically attacked or taken over, with consequences for the service.
Electronic means can be used to jam parts of the system or attempt limited
system takeovers. In the distant future, these threats may also affect the
space segment, with severe consequences.
GNSS failure or shutdown in any case, may have ominous economic
consequences – especially the greater the dependence on the system. In
addition, any system failure may have dire consequences in sectors requiring
continual and precise signals (such as aviation). In spite of these ominous
economics consequences, the future use and multitude applications of GNSS
technology cannot be denied.
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