Global Positioning System (GPS)

GPS Technology 1

Global Positioning System(GPS)

WDN PresentationCSN - SLIIT

GPS Technology 2

Team Members

1. Sachin Thishnika

2. Kusal Indika

3. Vidusha Rathnayaka

4. Nadeendra Yashaswin

5. Janaka Poddalgoda (Absent)

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Content

1. Introduction

2. What is GPS ?

3. How GPS Works

4. Applications of GPS

5. Drawbacks of GPS

6. Future Development

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Introduction

Navigation in early days North Star Compass LORAN & Decca Navigator

GPS project Developed under Department of

Defense

GPS is not alone

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What is GPS ?Global Navigation Satellite System

(GNSS)Provide

Position Timing Navigation

Three segments Space Control User

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What is GPS ? Cont.

Space segment 24 satellites At least six satellites on LOS

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What is GPS ? Cont.

Control Segment

Operate by US Air force

Consist of• Master Control Segment (MCS)• Alternative MCS• Dedicated ground antennas• Monitoring stations

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What is GPS ? Cont.

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What is GPS ? Cont.

User segment Consist of GPS receivers Calculate location using GPS signals

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How GPS WorksSatellite emit two signals

L1 (1575.42 MHz) UHF band – civil use L2 – (1227.60 MHz) - Military use Power 50w CDMA

GPS signal Pseudo random code Almanac data Ephemeris data

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How GPS Works

• Beacon –Radio Signal

• Travel time(t)=Sync of receive time – Satellite Time

• d=C*t

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How GPS Works Cont.

Triangulating

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Applications of GPS

GPS is an essential element of the global information infrastructure

It’s Free Open Dependable

“New uses of GPS are invented every day and are limited only by the human imagination.”

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Applications of GPS cont.

Aviation Cost effective solution Increase the safety and efficiency Three-dimensional positioning

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Applications of GPS cont.

Space Navigation solutions Altitude solutions Timing solutions & etc.

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Applications of GPS cont.

Survey & mapping Accuracy Reliability Interoperability

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Applications of GPS cont.

Differential GPS 10 meters to 10 centimeters Base station in known location Real-time DGPS

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Drawbacks of GPS

Signal multipath

Atmospheric effect

No GPS signals in Indoor Under water Under ground

Attacks

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Future Development

GPS III Enhanced signal reliability & accuracy L1C signal L2C signal Schedule to launch in 2015

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Future Development Cont.

No Selective Availability (SA)

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Future Development Cont.

L5 “safety-of-life” signal Two times powerful as L2C Focus on aviation & transportation Resistant to jamming & interference

High gain directional antenna 100 times more powerful than wide angle

antenna M-coded military signal

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Future Development Cont.

Cross platform receivers More accurate Fast convergence

GPS & GLONASS satellites

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