30-05-2012, 05:31 PM
THE GPS Technology
[attachment=23616]
INTRODUCTION
Throughout time people have developed a variety of ways to figure out their position on earth and to navigate
from one place to another. Early mariners relied on angular measurements to celestial bodies like sun and stars
to calculate their location. The 1920s witnessed the introduction of more advanced technique-radio navigationbased
at first on radios that allowed navigators to locate the direction of shore-based transmitters when in range.
Later development of artificial satellites made possible the transmission of more precise, line of sight radio
navigation signals and sparked a new era in navigation technology. Satellites are first used in position finding in
a simple but reliable 2D Navy system called Transit. This laid the groundwork for a system that would later
revolutionize navigation for ever-the Global Positioning System.
THE GPS SEGMENTS
The Space Segment
The space segments, also known as satellite segment, consist of 24
operational satellites revolving around earth in 6 orbital planes
approximately 600 GPS satellites are not geosynchronous. First satellite
was launched in the year 1978. The satellites take approximately 12 hours
to orbit Earth. These satellites revolve the earth in a circular pattern with
an inclined orbit. Out of the 24 satellites 21 are working satellites and the
remaining 3 satellites will be in standby. In the event of a satellite failure,
one of the spare space vehicles can be moved in to its place using modern
propulsion and guidance system. Each satellite circles the Earth twice
every day at an altitude of 20,200 kilometers. At a time 5 to 8 satellites
can be viewed by the user, there by ensuring worldwide coverage. The
information from three satellites is needed to calculate a navigational
unit’s horizontal location on Earth’s surface (2D-Reporting), but
information from four satellites enables a receiver to determine its altitude
(3D-Reporting). Each satellite contains a Cesium Atomic Clock and all
these clocks will be synchronized and are accurate within a few
nanoseconds.
CONCLUSION
Though originally designed to help US Forces around the world to locate targets
and move quickly, it is now being used across the world, from mountaineers
climbing up Mount Everest to sail boats journeying in to oceans. Its functions
have been extended to over positioning, tracking, mapping etc.
GPS’s future seems secure. Its biggest push now is the Federal Communications
Commission (FCC) enhanced 911 mandates. The new cell phones will be enabled
with GPS. GPS receivers in future will be able to give accuracy up to 5mm. there
is still room for improvement for GPS, as it does so, we will find it being used
more and more in our daily lives, to the point where it would be hard to perform
many travel and industry tasks without it.
[attachment=23616]
INTRODUCTION
Throughout time people have developed a variety of ways to figure out their position on earth and to navigate
from one place to another. Early mariners relied on angular measurements to celestial bodies like sun and stars
to calculate their location. The 1920s witnessed the introduction of more advanced technique-radio navigationbased
at first on radios that allowed navigators to locate the direction of shore-based transmitters when in range.
Later development of artificial satellites made possible the transmission of more precise, line of sight radio
navigation signals and sparked a new era in navigation technology. Satellites are first used in position finding in
a simple but reliable 2D Navy system called Transit. This laid the groundwork for a system that would later
revolutionize navigation for ever-the Global Positioning System.
THE GPS SEGMENTS
The Space Segment
The space segments, also known as satellite segment, consist of 24
operational satellites revolving around earth in 6 orbital planes
approximately 600 GPS satellites are not geosynchronous. First satellite
was launched in the year 1978. The satellites take approximately 12 hours
to orbit Earth. These satellites revolve the earth in a circular pattern with
an inclined orbit. Out of the 24 satellites 21 are working satellites and the
remaining 3 satellites will be in standby. In the event of a satellite failure,
one of the spare space vehicles can be moved in to its place using modern
propulsion and guidance system. Each satellite circles the Earth twice
every day at an altitude of 20,200 kilometers. At a time 5 to 8 satellites
can be viewed by the user, there by ensuring worldwide coverage. The
information from three satellites is needed to calculate a navigational
unit’s horizontal location on Earth’s surface (2D-Reporting), but
information from four satellites enables a receiver to determine its altitude
(3D-Reporting). Each satellite contains a Cesium Atomic Clock and all
these clocks will be synchronized and are accurate within a few
nanoseconds.
CONCLUSION
Though originally designed to help US Forces around the world to locate targets
and move quickly, it is now being used across the world, from mountaineers
climbing up Mount Everest to sail boats journeying in to oceans. Its functions
have been extended to over positioning, tracking, mapping etc.
GPS’s future seems secure. Its biggest push now is the Federal Communications
Commission (FCC) enhanced 911 mandates. The new cell phones will be enabled
with GPS. GPS receivers in future will be able to give accuracy up to 5mm. there
is still room for improvement for GPS, as it does so, we will find it being used
more and more in our daily lives, to the point where it would be hard to perform
many travel and industry tasks without it.