Gps Surveys
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Transcript of Gps Surveys
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Gangtok Station
Sat. Visibility and GDOP
status for the proposedsurvey period Using
Trimble Planning Software
Acquire a current
Almanac File Select the location and
date of survey for the
proposed GPS fieldwork
GPS Mission Planning
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GPS SURVEYING METHODS
y Post-Processed
Static: Stationary on point for extended periods of time.
Rapid Static: Stationary on point for typical occupationtimes of 3 to 20 minutes.
Kinematic: Stationary initialization, then dynamic datacollection.
y Real-Time
DGPS: Code solutions suitable for most mapping andGIS applications. RTCM correction is typical.
Real-Time Kinematic: DGPS code and carrier solutioncapable of producing centimetric results.
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Static positioning technique
Rapid static positioning technique
Stop-and-go technique.
Kinematic positioning technique
Differential GPS
GPS SURVEYING TECHNIQUES
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Observation time is longer and is dependent onbaseline length
Longer baseline length (10km to 1000km)
Type of GPS used is dual frequency
STATIC GPS SURVEYING
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Observation time is shorter and is dependent on Baseline length
Type of GPS used whether single frequency or dual
frequency Number of satellite tracked
RAPID STATIC GPS SURVEYING
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Users receiver continued totrack satellite while it is in
motion
It is known as stop-and-go
technique because the
coordinate of receiver are only of
interest when it is stationery (In
stop part) and the receiver
continue to function while it is
being moved (the go part)
STOP-AND-GO GPS SURVEYING
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Generalization of stop and go techniqueIn Kinematic Surveying the position of antenna also
determined while receiver is in motion
KINEMATIC GPS SURVEYING
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DGPS is an enhancement to GPS. It use a fixed ground based reference station of known
coordinates.
Calculates the difference (error) between known and observed coordinates (from satellites) at reference station.
Transmit the corrections to unknown sites or rover station.
It requires minimum two GPS receivers one for reference station equipped with a transmitter
other for rover
THE DGPS TECHNIQUE
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Differential GPS DGPS
Post processing or Offline
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Real Time Differential GPS
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Observed coordinates = (x1 , y1 , z1)
Real Time Differential GPS
True coordinates = (xo , yo , zo)
Corrections
(x=x1 xo(y= y1 yo
(z= z1 zo
Corrections ((x, (y, (z)
transmitted Rover
DGPS Reference StationDGPS Rover Station
Observed coordinates = (x2, y2, z2)
Corrected
coordinates
X2+(xy2+(y
Z2+(Z
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GPS SOLUTIONS
y Autonomous
Single receiver solution (regardless of type).0 10 meter variable accuracy.
y DGPS
Differential Code solution. 1 3 meters of accuracy.
y CPD Float
Carrier Phase Differential Float solution. 10 cm to 1 maccuracy.
y CPD Fixed
Carrier Phase Differential Fixed solution. 1 2 cmaccuracy. Survey grade.
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GPS Modernization
NEW Navigation signals
- Civilian L2C code
- Military M-Code
-L5 frequency
- New civilian L1C code
Block III satellite improvement
- satellite clock errors automatic correction
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Global Navigation Satellite Systems
Existing and future GNSS NAVSTAR GPS
USA, military system, developed in the 70s
GLONASS
Russian equivalent to GPS, developed in the 80s GALILEO
Europes GNSS, civil system, under development
Compass
Chinas global navigation satellite system, underdevelopment
IRNSS
Indias global navigation satellite system, under
development
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Indian Regional Navigation Satellite System(IRNSS)
IRNSS is planned to be an independentregional navigation system covering anarea of about 1500 kms around India.
7 satellites constellation
Will provide
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GPS Applications
Utility mapping
Forestry and precision farming
Construction applications
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GPS Applications
GPS for monitoring structural deformations
GPS for marine and land seismic surveying.
GPS for airborne mapping.
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GPS Applications
GPS for airborne mapping.
Classicalaribone photogrammery LIDARsystemmapping