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What is a GPS System ?
First launched in 1978, the GPS or
Global Positioning system is the only fully operational Global
Navigation Satellite System or GNSS. Its primal use lies in the
field of navigation along with map making and land surveying.
Moreover, GPS is also credited with providing exact and accurate
time reference used in a wide range of applications like study
of earthquakes and synchronization of telecommunications
network. Today more than twelve GPS satellites are placed in the
Earth’s medium orbit which is responsible for the transmission
of signals allowing the receivers to determine the location,
speed and direction.
This application was started by the Defense division of the
United States of America and was called NAVSTAR GPS (Navigation
Satellite Timing And Ranging Global Positioning System). The
United States Air Force 50th Space Wing is responsible for the
handling of the satellite constellation; managing this whole
system costs the department almost $400 USD per year. However,
for the citizens and civilians, this comes free of cost.
The origin of GPS
GPS is designed on the similar lines of Decca Navigator and
LORAN, the ground based radio navigatioon systems, which were
formulated in the early half of the 1940s and used during the
Second World War. Developing the GPS further happened after the
launch of the first Sputnik in 1957 by the Soviet Union.
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The idea struck Dr. Richard B.
Kershner, one of the U.S. scientists who were monitoring the
radio transmissions of Sputnik when he observed that due to
Doppler’s effect, the frequency of the signal sent by Sputnik
was higher as the satellite moved forward and lower as it moved
away. Dr. Kershner’s team realized that as they were aware of
their precise location on the globe, they could nail the exact
position of the satellite on its orbit by measuring the Doppler
distortion.
Transit, the first satellite
navigation system used by the United States Navy, was
successfully tested for the first time in the year 1960. Transit
was designed in such a way that was able to give a navigational
fix tentatively once in every hour using a five satellite
constellation. The Navy developed another Timation satellite in
the year 1967 that was able to place accurate clocks in space –
one of the most important features of the GPS system.
Immediately after this, in 1970, world’s first radio navigation
system, Omega Navigation System was introduced. This ground
based navigation system was founded on signal phase comparison. |
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What are
the various uses of GPS ?
GPS is used for several applications. These include:
The Armed forces: With the
aid of GPS, accurate targeting of weapons like cruise missiles
and precision guided munitions can be used. However, to stop any
wrong usage of this GPS guidance, either by the enemy or any
terrorist groups, the government of the United States monitors
all the exports of the civilian receivers. One of the most
important uses of GPS satellites is that they carry nuclear
detonation detectors which play a vital role in Nuclear
Detonation Detection System of the United States.
Automobile navigation:
Vehicles are often furnished with GPS receivers for showing the
moving maps and also providing information on the location,
direction, speed and the streets and prominent landmarks.
Aircraft navigation: GPS
receivers are also used in aircraft navigation systems to reveal
the ‘moving map’. For accuracies in the final approach and
landing, aircraft GPS receivers like WAAS or LAAS are also used.
Marine navigation: GPS
receivers are also used by ships and boats to navigate the
lakes, seas and oceans. These receivers are designed in such a
way that they have features which are extremely important in
water – the function of “man overboard” or MOB. This unique
feature allows the sailors and engineers to locate the point pr
place where the person has fallen without any delay, making
rescue operations much quicker and easier. They are also used
for increasing the security of shipping traffic by enabling the
AIS.
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Others:
Bicycles used for racing purposes also use GPS so that the
riders can plot their routes in advance and plan the course.
This saves them from the trouble of stopping at frequent
intervals and referring to separate maps. Some GPS receivers are
particularly designed for cycles with special mounts and
housings. Similarly professional mountaineers and climbers can
also use GPS to an idea of their exact positions, without having
to refer to separate maps. This is of great help as in cases
when the climbers or hikers have lost their way, the chances of
rescue with this data become much higher.
Tracking: To locate a lost
(or any) vehicle, a person or even a pet, GPS tracking systems
can be used. This tracking system will observe and trace the
position of the particular object at regular intervals and keep
a record of the movements. This information then can either be
stored in the system or transmitted to a computer with the help
of a radio or cellular modem. Some of the new tracking systems
even allow a real time viewing of the location on the Internet
with a web browser.
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Some
facts
• The first modern Block-II satellite was set up on 14th
February, 1989.
• The first GPS satellite was launched in August, 1991. this
satellite is fully operational till date.
• It was only at the end of 1993 when the GPS attained the
initial operational capability.
• A constellation of all the 24 Earth orbiting satellites was
completed on 17th January, 1994.
• In 1996, the President of United States, Bill Clinton passed a
regulation that GPS should be used as a dual system – for both
the civilians and the the armed forces. An Intragency GPS
Executive Board was set up to take care of this GPS system as a
national asset.
• The Executive Board was replaced by the National Space Based
Positioning , Navigation and Timing Executive Committee in the
year 2004 by the US President George W Bush.
• The latest GPS satellite was launched on 17th November, 2006.
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Article Contributed By: Sukanaya
Banerjee
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