CORS - GPS

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CONTENTS

Basics of GNSS Definition Usage Area Structure of the instrument Properties Precision and Accuracy Comparison

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WHAT IS GNSS ?

A satellite navigation or sat nav system is a system of satellites that provide autonomous geo-spatial positioning with global coverage. GPS | USA GLONASS | Russia Galileo | EU Regional navigation systems Beidou | China DORIS | France IRNSS | India QZSS |Japan

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WHAT IS GPS ? The Global Positioning System (GPS) is a

space-based global navigation satellite system (GNSS) that provides location and time information in all weather and at all times and anywhere on or near the Earth when and where there is an unobstructed line of sight to four or more GPS satellites. It is maintained by the United States government and is freely accessible by anyone with a GPS receiver.

GPS satellites broadcast the time and data about their location

a GPS receiver compares signals from at least three or four GPS satellites to determine it's own location

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HOW GPS WORKS? (VİDEO)

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LOCATİNG POSİTİONLeast 4 satellites detects receivers position in 3D(x,y,z) and GPS time (t).

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GPS RECEİVER PRİNCİBLE

A GPS receiver figures out how far away it is from each satellite based on how much time it takes a broadcast signal to travel from the satellite to the receiver. (A signal takes more time to reach you if you're farther away.)

Since the location of each GPS satellite is known, the receiver's location can be determined by "triangulating" the distances from several satellites

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USERS

GPS receivers which isconverting SV signals into location and time.

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WHAT IS CORS ?

CORS is acronym for “Continously Operating Reference Stations” and it is stands for accuracy of GPS data. CORS is a reference network includes GPS points which is working in RTK princible. Main goal in here is eleminating erros and achieving coordinates with big accuracy in real time (24/7). With CORS only one receiver is suffice for users position detecting.

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• Cadastral surveying• GIS - Map• Deformation monitoring• Large construction sites• Municipal services• Precision agriculture• Hydrographic surveying• Machine control - Navigation• Road - Railway Construction• Underground construction companies / institutions• Coordinated the point of producing• Plate motion tracking

USAGE AREA

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USAGE AREA // WHERE WE USE

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PROVİDES DATA FOR

Surveying Navigation GIS/LIS Remote Sensing Weather Forecast Satellite Tracking Geopyhsics Time Transfer

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STRUCTURE

Antenna Receiver Power Plant

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STRUCTURE // SOFTWARE

Geo++ (Thales and Topcon) Leica Network Software Package Trimble GPSNet

Connected receivers via LAN / WAN GPRS / EDGE ADSL

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WİTH CORS

Single coordinate system

Regular presicion No need to find a

benchmark in field Not necassary setup

base stations You can watch

crustal movements, moisture distiribution in

atmosphere free electron distribution

in ionosphere

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ACCURACY // ERROS İN GPS

Source of Errors• Ionospheric effects ± 5 meters• Tropospheric effects ± 0.5 meter• Ephemeris errors ± 2.5 meters• Satellite clock errors ± 2 meters• Multipath distortion ± 1 meter• Numerical Errors ± 1 meter

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ACCURACY

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ACCURACY

Provides “cm” accuracy with RTK principle

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COMPARİSON

National CORS United CORS

The station will run continuously for a long period

The station working in 8 hours a day, 5 days in a week

Datas can be obtained with NGS, CORS web pages

The officer will be provided a link to the itself website

All data is permanently archived at NGS

The data are published at least 7 days as a contributor on the web page

Antenna position is recalculated every day

Antenna position is recalculated every 30 days

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QUESTİONS