Gps Surveys

8/6/2019 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.

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