Lecture 7- Global Positioning gps

8/7/2019 Lecture 7- Global Positioning gps

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Lecture 7:

Global PositioningSystem (GPS)

By: Zuliana Ismail,2010


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Learning Outcomes

At the end of this lecture, the student shouldbe able to:

Explain the basic working principle of GPS

Describe the advantages of GPS


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Introduction

GPS is stands for Global Positioning System.

Official name of GPS is Navigational Satellite

Timing And Ranging Global Positioning System

(NAVSTAR GPS)


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Introduction


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What is GPS-Global Positioning

System?

4 satellites/orbit. Total orbit = 6.

Thus, GPS consists of 24

satellites.

Each satellite orbits the earthevery 12 hours (2 complete

rotations every day).

Thus, every point on the Earthwill always be in radio contact

with at least 4 satellites.


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GPS Segment


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What is the purpose of GPS

The purpose of GPS is to show you your exactposition on the Earth anytime, in any weather,

anywhere.


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Who developed GPS?

First developed by the US DOD (United StatesDepartment of Defense)

Feasibility studies begun in 1960s.Pentagon

appropriates funding in 1973.

First satellite launched in 1978. System

declared fully operational in April, 1995.

Open to the public, 2000. Currently controlled

by the United States Air Force.

It costs about $750 million to manage and

maintain the system per year


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Help Who CanUse GPS

Military

Automobile

Aircraft Navigation

Marine

Individual


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Who can use GPS?

Automobiles: show moving maps (highways,buildings)

Military: target detection.

Aviation: for aircraft navigation

Marine: Provides precise navigation

information to boaters.


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Why do we need GPS?

One drawback of using radio waves generated onthe ground (like NDB,VOR,DME or ILS) is that

you have only two choices:

A system that is very accurate but doesnt cover

a wide area

A system that covers a wide area but is not very

accurate

We need a powerful system such GPS because

GPS can provide accurate information

and cover wide area.


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GPS Frequency

GPS operates in the UHF band.

There are two types of services available:

1. For Civilian/ResearchUse Standard

Positioning System

L1 (1575.42 MHz), L2 (1227.60 MHz), L5

(1176.45 MHz) For Civilian

L4 (1379.913 MHz) For Research

2. ForMilitary Use Precise Positioning System

L3 (1381.05 MHz)


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GPS Receiver

Handheld GPS ReceiversCasio GPS wristwatch


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H

OW

GPSW

ORKS?


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How GPS works

GPS receivers tuned to the frequencies of GPS satellites.

Each GPS satellites then transmit signals to the GPSreceivers . The signals, moving at the speed of light, c =3 x 10 m/s.

These signals indicates satellites location and the

current time. The GPS receiver measures the time taken for a signal to

travel from satellite to receiver.

The distance to each GPS satellites can be calculated:

Distance = Speed of Light x Time

Knowing the distance from at least 4 GPS satellites, theGPS receiver can calculate the position (latitude,longitude and altitude )


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GPS IN AVIATION


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GPS receiver in the aircrafts cockpit

Can provide the pilot with navigational information in

terms of longitude, latitude and altitude.


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What GPS can tell you?

GPS also can tell you

What direction you are heading

Speed (How fast you are going)

Your altitude

A map to help you arrive at a destination

Distance (How far you have traveled)

Time (How long you have been traveling)

Estimated time of arrival (When you will

arrive)


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Help ADVANTAGES OF GPSINAIRCRAFTNAVIGATION


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ADVANTAGES OF GPS

in AIRCRAFTNAVIGATION

GPS can reduce the aircraft delays problem,

GPS can reduce journey time and fuel

consumption

GPS can maintain high levels of flight safety. GPS can increase airway & landing capacity for

aircraft.

GPS more economical


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A GPS receiver in the cockpit

provides the pilot with

accurate position data and

helps him keep the airplane on

course.


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Using GPS, aircraft can fly the

most direct routes between

airports


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Advantages of using GPS in Aircraft

Navigation

GPS can reduce the aircraft delays problem GPS can provide accurate & continuous data

during all-weather condition.

This can avoid flight delays.

GPS can reduce fuel consumption Civil aircraft typically fly from one waypoint

to another.

With GPS, an aircraft's computers can beprogrammed to fly a direct route to adestination.

This can save fuel and time


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Navigation

GPS can maintain high levels of flight safety. Improved situational awareness (quick alert

about emergency)

GPS also can simplify and improve themethod of guiding planes to a safe landing,especially in poor weather.

GPS can increase airway & landing capacity for

aircraft. GPS system more flexible. Many aircrafts can

depend on GPS system at one time.


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Navigation

GPS more economical

Maintain economies from reduced

maintenance and operation of ground-based

systems (such as VOR/DME/NDB station)


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Waypoints

Waypoints are locations or landmarks that canbe stored in your GPS.

Waypoints may be entered directly by taking areading with the unit at the location itself,

giving it a name, and then saving the point. Once entered and saved, a waypoint remains

unchanged in the receivers memory untiledited or deleted.


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Waypoints

Latitude and

Longitude

Your location

Direction of

waypoint

Date

and

Time

Waypoint


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Help GPS APPLICATION FORNAVIGATION SYSTEM


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GPS NAVIGATION SYSTEM

There are two advanced GPS NAVIGATIONSystem which are

1. LAAS - Local Area Augmentation

System.

2. WAAS - Wide Area Augmentation

System


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Local Area Augmentation System

(LAAS)

LAAS is a precision approach and landingsystem that relies on the Global Positioning

System (GPS) to broadcast highly accurate

information to aircraft on the final phases of a

flight.

LAAS support precision approaches and landing

capability to aircraft operating within a 20- to

30-mile radius of the airport.

LAAS approaches will be designed to avoid

obstacles, restricted airspace, noise-sensitive

areas, or congested airspace.


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Local Area Augmentation System (LAAS)

One LAAS coversmultiple runway ends

Contributing

technology for high

precision terminal area

navigation services.

Quick data transferring

among LAAS, Aircraftand GPS satellites


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Benefits of LAAS

Replaces ILS systems that are expensive tomaintain

Increases efficiency of arrival and departure

operations and improves usage of runway

capacity

Supports fuel efficiency.

Improves access to airports during extremely

low visibility operations


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Wide Area Augmentation SystemWide Area Augmentation System

(WAAS)(WAAS)

38 ReferenceStations

3 MasterStations

4 GroundEarth Stations

2 GeostationarySatellite Links

2 OperationalControl Centers


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WAAS Benefits

Serves all classes of aircraft during flightoperations in all weather conditions at all

locations.

Provides precise navigation and landing

guidance to pilots at all airports, including

thousands that have no ground-based

navigation aids

Overcomes obstacles to ground-based systems,such as mountainous terrain


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WAAS Benefits

Reduces operating and maintenance costsassociated with ground-based navigation aids

Makes more airspace usable to pilots, provides

more direct en-route paths, and provides new

precision approach services to runway ends

Through international cooperation provides a

global navigation system for all users


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GPS Limitations

The GPS must see the satellites, so it does notwork well in dense forests, inside caves,

underwater, or inside buildings.

Signal Interference: Sometimes the signals

interfered before they reach the receivers.

Changing atmospheric conditions change the

speed of the GPS signals as they pass through

the Earth's atmosphere


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Obstruction


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Earths Atmosphere

Solid Structures

Metal Electro-magnetic Fields

Signal Interference


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Question Bank

1. Explain how GPS works. (9m)

2. Describe 3 advantages of GPS. (6m)

Lecture 7- Global Positioning gps

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Transcript of Lecture 7- Global Positioning gps