Originally designated the NAVSTAR
(Navigation System with Timing And Ranging) Global Positioning System, (GPS) was
developed by the US Department of Defense to provide all-weather round-the-clock
navigation capabilities for military ground, sea, and air forces. Since its
implementation, the GPS system has also become an integral asset in numerous
civilian applications and industries around the globe, including recreational
uses (e.g. boating, aircraft, hiking), corporate vehicle fleet tracking, and
surveying.
The GPS system employs 24 spacecraft in 20,200 km circular orbits
inclined at 55 degrees. These spacecraft are placed in 6 orbit planes with four
operational satellites in each plane. All launches have been successful except
for one launch failure in 1981. The full 24-satellite constellation was
completed on March 9, 1994.
The first eleven spacecraft (GPS Block 1) were
used to demonstrate the feasibility of the GPS system. The orbit inclination
used for these satellites was 63 degrees, differing from the 55 degrees used for
the operational system. The Block 2 spacecraft began the operational system. The
Block 2A spacecraft (A = Advanced) were a slight improvement over the Block 2.
The Global Positioning System (GPS) was designed as a dual-use system with
the primary purpose of enhancing the effectiveness of U.S. and allied military
forces. GPS is rapidly becoming an integral component of the emerging Global
Information Infrastructure, with applications ranging from mapping and surveying
to international air traffic management and global change research. The growing
demand from military, civil, commercial, and scientific users has generated a
U.S. commercial GPS navigation systems equipment and service industry that leads
the world. Augmentations to enhance basic GPS services could further expand
these civil and commercial markets.
GPS systems receivers use triangulation
of the GPS satellites' navigational signals to determine their location. The
satellites provide two different signals that provide different accuracies.
Coarse-acquisition (C/A) code is intended for civilian use, and is deliberately
degraded. The accuracy using a typical civilian GPS receiver with C/A code is
typically about 100 meters. The military's Precision (P) code is not corrupted,
and provides positional accuracy to within approximately 20 meters. Numerous
on-line tutorials on how GPS works and its applications are available, including
those at the University of Texas and Rentec International. GPS systems
satellites are controlled at the GPS Master Control Station (MCS) located at
Falcon Air Force Base outside Colorado Springs, Colorado. The ground segment
also includes four active-tracking ground antennas and five passive-tracking
monitor stations.
GPS receiver technology has developed by leaps and bounds
over the last few years. GPS receivers were initially the size of a suitcase
with the antenna the size of a kid’s blow up swimming pool. Over time, the
system has been developed into a civilian friendly program, and GPS receiver
technology has miniaturized as well. Automobile GPS receivers are the size of a
deck of cards. The gps receiver used in hand held devices is not much larger
than a small cell phone. Many newer cell telephones have a GPS receiver integral
in their hand set. As manufacturers develop the GPS receiver, they will have to
work through display, power use and dexterity limitations. An individual will
need a screen with a size that can be viewed from any angle and at a reasonable
distance. The GPS receiver is generally always on while in use, so managing
power will continue to be an on going problem. The ability to push the small
buttons will limit just how small a GPS receiver can be. As touch screens
develop and other input systems are introduced, we will see the GPS receiver
continue to change in appearance and use.
Author: John B. Whitsell
Making Tracks GPS
http://www.makingtracksgps.com
Information
referenced from NASA and USCG data
Source:
(Navigation System with Timing And Ranging) Global Positioning System, (GPS) was
developed by the US Department of Defense to provide all-weather round-the-clock
navigation capabilities for military ground, sea, and air forces. Since its
implementation, the GPS system has also become an integral asset in numerous
civilian applications and industries around the globe, including recreational
uses (e.g. boating, aircraft, hiking), corporate vehicle fleet tracking, and
surveying.
The GPS system employs 24 spacecraft in 20,200 km circular orbits
inclined at 55 degrees. These spacecraft are placed in 6 orbit planes with four
operational satellites in each plane. All launches have been successful except
for one launch failure in 1981. The full 24-satellite constellation was
completed on March 9, 1994.
The first eleven spacecraft (GPS Block 1) were
used to demonstrate the feasibility of the GPS system. The orbit inclination
used for these satellites was 63 degrees, differing from the 55 degrees used for
the operational system. The Block 2 spacecraft began the operational system. The
Block 2A spacecraft (A = Advanced) were a slight improvement over the Block 2.
The Global Positioning System (GPS) was designed as a dual-use system with
the primary purpose of enhancing the effectiveness of U.S. and allied military
forces. GPS is rapidly becoming an integral component of the emerging Global
Information Infrastructure, with applications ranging from mapping and surveying
to international air traffic management and global change research. The growing
demand from military, civil, commercial, and scientific users has generated a
U.S. commercial GPS navigation systems equipment and service industry that leads
the world. Augmentations to enhance basic GPS services could further expand
these civil and commercial markets.
GPS systems receivers use triangulation
of the GPS satellites' navigational signals to determine their location. The
satellites provide two different signals that provide different accuracies.
Coarse-acquisition (C/A) code is intended for civilian use, and is deliberately
degraded. The accuracy using a typical civilian GPS receiver with C/A code is
typically about 100 meters. The military's Precision (P) code is not corrupted,
and provides positional accuracy to within approximately 20 meters. Numerous
on-line tutorials on how GPS works and its applications are available, including
those at the University of Texas and Rentec International. GPS systems
satellites are controlled at the GPS Master Control Station (MCS) located at
Falcon Air Force Base outside Colorado Springs, Colorado. The ground segment
also includes four active-tracking ground antennas and five passive-tracking
monitor stations.
GPS receiver technology has developed by leaps and bounds
over the last few years. GPS receivers were initially the size of a suitcase
with the antenna the size of a kid’s blow up swimming pool. Over time, the
system has been developed into a civilian friendly program, and GPS receiver
technology has miniaturized as well. Automobile GPS receivers are the size of a
deck of cards. The gps receiver used in hand held devices is not much larger
than a small cell phone. Many newer cell telephones have a GPS receiver integral
in their hand set. As manufacturers develop the GPS receiver, they will have to
work through display, power use and dexterity limitations. An individual will
need a screen with a size that can be viewed from any angle and at a reasonable
distance. The GPS receiver is generally always on while in use, so managing
power will continue to be an on going problem. The ability to push the small
buttons will limit just how small a GPS receiver can be. As touch screens
develop and other input systems are introduced, we will see the GPS receiver
continue to change in appearance and use.
Author: John B. Whitsell
Making Tracks GPS
http://www.makingtracksgps.com
Information
referenced from NASA and USCG data
Source:
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