26-02-2013, 12:35 PM
Global Positioning System
Global Positioning System.pptx (Size: 2.16 MB / Downloads: 30)
What is GPS ?
INTRODUCATION
The global positioning system(GPS) is a network of 24 NAVSTAR satellites orbiting at a distance of 20,200kms from the surface of the earth . Originally established by the US department of defense(DOD). The system’s positioning and timing data are used for a variety of applications, including air, land and sea navigation, vehicle and vessel tracking, surveying and mapping ,asset and natural Resource management. GPS is the shortened form of NAVSTAR GPS. This is an acronym for Navigation System Timing And Ranging.
More about GPS satellites
The GPS is a Constellation of 27 satellites
(24 active + 3 spare),31 satellites March 2008
Orbit : 12,600 miles above earth (10,900 nautical miles)
The orbital period is one-half a sidereal day, 12 hours
Development History:
1969-Defense Navigation Satellite System (DNSS) formed
1973-NAVSTAR Global Positioning System developed
1978-first 4 satellites launched Delta rocket launch
1993-24th satellite launched, initial operational capability
1995-full operational capability
May 2000-Military accuracy available to all users ( SA turned Off)
GPS Control Segment
The GPS Control Segment is
composed by a network of Monitor
Stations (MS), a Master Control
Station (MCS)and the Ground
Antennas (GA).The Master Control
Station (MCS) processes the
measurements received by the
Monitor Stations (MS)to estimate
satellite orbits (ephemerides) and
clock errors, among other parameters,
and to generate the navigation
message. These corrections and the navigation
message are uploaded to the satellites through
the Ground Antennas,
Getting Perfect timing
Accurate timing is the key to measuring distance to satellites.
Satellite are accurate because they have atomic clocks on board.
Receiver clock don’t have to be too accurate because an extra satellite range measurement can remove errors.
Global Positioning System (GPS) navigators use the mathematical technique of trilateration to determine user position, speed, and elevation. GPS navigators constantly receive and analyze radio signals from GPS satellites, calculating precise distance (range) to each satellite being tracked.
In geometry, trilateration is the process of determinating absolute or relative locations of points by measurement of distances, using the geometry of circles, spheres or triangles.
Why we need DGPS ?
DGPS is used to correct the various inaccuracies in the GPS system.
High performance GPS receiver at a known location.
DGPS can measure good to couple of meters in moving applications & better in stationary situations.
With it, GPS becomes a universal measurement system capable of positioning things on a very precise scale.
DGPS gives accuracy of 3-5 meters, while GPS gives accuracy of around 15-20 meters.
Requirements for a DGPS:
Reference station
Transmitter
Operates in the 300khz range
DGPS correction receiver
Serial RTCM-SC 104 format
GPS receiver
Global Positioning System.pptx (Size: 2.16 MB / Downloads: 30)
What is GPS ?
INTRODUCATION
The global positioning system(GPS) is a network of 24 NAVSTAR satellites orbiting at a distance of 20,200kms from the surface of the earth . Originally established by the US department of defense(DOD). The system’s positioning and timing data are used for a variety of applications, including air, land and sea navigation, vehicle and vessel tracking, surveying and mapping ,asset and natural Resource management. GPS is the shortened form of NAVSTAR GPS. This is an acronym for Navigation System Timing And Ranging.
More about GPS satellites
The GPS is a Constellation of 27 satellites
(24 active + 3 spare),31 satellites March 2008
Orbit : 12,600 miles above earth (10,900 nautical miles)
The orbital period is one-half a sidereal day, 12 hours
Development History:
1969-Defense Navigation Satellite System (DNSS) formed
1973-NAVSTAR Global Positioning System developed
1978-first 4 satellites launched Delta rocket launch
1993-24th satellite launched, initial operational capability
1995-full operational capability
May 2000-Military accuracy available to all users ( SA turned Off)
GPS Control Segment
The GPS Control Segment is
composed by a network of Monitor
Stations (MS), a Master Control
Station (MCS)and the Ground
Antennas (GA).The Master Control
Station (MCS) processes the
measurements received by the
Monitor Stations (MS)to estimate
satellite orbits (ephemerides) and
clock errors, among other parameters,
and to generate the navigation
message. These corrections and the navigation
message are uploaded to the satellites through
the Ground Antennas,
Getting Perfect timing
Accurate timing is the key to measuring distance to satellites.
Satellite are accurate because they have atomic clocks on board.
Receiver clock don’t have to be too accurate because an extra satellite range measurement can remove errors.
Global Positioning System (GPS) navigators use the mathematical technique of trilateration to determine user position, speed, and elevation. GPS navigators constantly receive and analyze radio signals from GPS satellites, calculating precise distance (range) to each satellite being tracked.
In geometry, trilateration is the process of determinating absolute or relative locations of points by measurement of distances, using the geometry of circles, spheres or triangles.
Why we need DGPS ?
DGPS is used to correct the various inaccuracies in the GPS system.
High performance GPS receiver at a known location.
DGPS can measure good to couple of meters in moving applications & better in stationary situations.
With it, GPS becomes a universal measurement system capable of positioning things on a very precise scale.
DGPS gives accuracy of 3-5 meters, while GPS gives accuracy of around 15-20 meters.
Requirements for a DGPS:
Reference station
Transmitter
Operates in the 300khz range
DGPS correction receiver
Serial RTCM-SC 104 format
GPS receiver