Navigation System

Date:

Group Members

• Aamir Sultan• Hamza Parvez• Muhammad Usman • Adnan Walidad • Muhammad Waqar

The Presentation will explain:

• Introduction to Navigation System• Navigation System in automobiles• History• Components• Working• Errors &limitations• Applications

Introduction &History Presentor:Muhammad Usman

Introduction

What is a Navigation System?• The word Navigation is a combination of two

Latin words “navis” means boat and “agire” means guide .• Traditionally meant the art or science of

moving the ships and other watercraft safely from one place to another.

• Today word Navigation used in broad sense. Navigation system define as a system

providing useful information to determine the position of a boat, car or airplane etc,

Navigation System In Automobiles

• GPS is used in automobiles for Navigation purposes.

What is GPS?• GPS stands for Global Positioning System.• GPS is the first man made Satellite

Navigation System.

History

When GPS started?• The GPS project was developed in 1973.• It became fully operational in 1995. Who invented the GPS?• GPS was invented by two American engineers

Ivan Alexander , Bradford Parkinson and an American scientist Roger L. Easton with the co-operation of US Deptt Of Defense(DoD).

Why did they start GPS?• To keep the track of enemies, but later in

1991 they open it for civilians.

History

Ivan Alexander( physicist &engineer)

Bradford Parkinson(engineer)

Roger L.Easton(scientist)

Inventors of GPS

Components Presentor:Adnan Walidad

What are the components of GPS?• There are 3 components of GPS.1)Space ComponentIt includes the satellites and Delta rockets. What Delta rockets do? • They launch the satellites. What is a satellite?• A GPS satellite is a smaller object in space which is

orbiting in its orbits around the earth at a height of 20,200km and with a speed equal to 14,000 km/hour, relative to the Earth .A satellite completes two revolution around earth in one day.

Components

Components

It is operating on solar energy. It sends GPS signals to the earth.

What is a GPS signal?• A GPS signal is a radio signal sent by the GPS

satellite ,the signal travels at speed of light(c=3x10^8 m/s).

• A GPS signal contains information about the satellite.

How many satellites GPS contain?• There are 24 satellites currently working in

GPS ,but in case of any technical error in any of 24 ,further satellites are launched.

Components

Delta Rocket(satellite launcher)

GPS satelliteArrangement of satellites in space around earth

Components

What is an Atomic clock?• An atomic clock uses the vibrations of an

atom to calculate the time .

Components

Atomic Clocks

Components

2)Control componentThe control component of a GPS includes the

stations around the world where the GPS satellites are monitored. These bases include Schriever Air Force Base in Colorado, a station in Hawaii, a station on Ascension Island, another on Kwajalein Island, and one on Diego Garcis Atoll. The control component is responsible for ensuring that the GPS satellites are in working condition and functioning properly.

Components

Different Locations of Control Stations

Components

3)User Component• The user component includes the GPS receivers. What is a GPS receiver ?• A GPS receiver is a device which receives GPS signal sent by a satellite.

A GPS receiver consist of a clock and almanac. What is a GPS receiver clock?• A GPS receiver has a clock which measures the time of the signal from

satellite to reach the GPS receiver. What is an almanac?• An almanac is a set of information. What is the function of almanac?• An almanac is just like a diary it tells the position of satellite to the

receiver , e.g. the satellite will be above the city A at 9:30:10 pm and it will be above the city B at 3:10:01 am. So it knows the position of every satellite at any time.

Components

GPS receivers

Working Presentor:Aamir Sultan

Working

How GPS works?1. Distance of receiver from 3 satellites.2. Location of these 3 satellites.3. Distance of receiver from these locations.

Working

How the distance of receiver from satellite is determined?

• s=vt (m) s=ct (m) where, c=speed of light=3x10^8 (m/s)

Working

Car with GPS receiver

Satellite 1

Distance between satellite

and receiver

s=x

Working

How the location of satellite is determined How much above the city ?• The GPS satellites are at a distance of

20,200km above the earth .

Working

Car with GPS receiver

Satellite 1

Distance between satellite

and receiver

s=x

20,2

00 K

m

City A

Working

How distance between GPS receiver and city A is determined?

Pythagoras theorem Hyp^2=Perp^2+Base^2

2

Hyp

Working

Car with GPS receiver

Satellite 1

Distance between satellite

and receiver

s=x

p=20

,200

Km

b=?

s^2=p^2+b^2 b^2=s^2-p^2

Distance between receiver and city A

Working

Car with GPS receiver

Satellite 1

Distance between satellite and receiver

s=x

p=20

,200

Km

b

Distance between receiver and city A

Other Possibilities

Working

b

Working

Satellite 2

cCity B

Working

c

Working

Map •Plot the data on map

Working

Trilatrelation

Working

P1

P2

Working

Still we do not know that whether we are at position P1 or P2.

Satellite 3

d City C

working

d

Working

P1

P2

Working

So we are at position P1 on the map

Errors & Limitations Presentor:Hamza Parvez

Errors &LimitationsThere are following errors in GPS. Multipath Errors Almanac Errors Errors In GPS Clock What are multipath errors During their traveling from satellite to GPS

receiver ,GPS signals can strike with trees, electromagnetic field, buildings etc. After striking these are reflected at a certain angle and thus increases the time to reach the receiver when the time .Producing error in distance.

Errors &Limitations

How multipath errors are corrected? They are corrected by introducing a

stationary receiver at a high altitude. First the GPS signal sent to these stationary satellite and then sent to car GPS signal

receiver. This method is called “differential method”.

Errors &Limitations

What are Almanac Errors?• Due to the pull force of sun and moon on the

satellites, the position of their orbits are slightly changed .

• Now ,although the position of their orbits are changed but almanac shows the orignal position .

Errors &Limitations

How almanac error is corrected?• It is corrected by updating the almanac. Who updates the almanac?• Almanac is updated by the control

department.

Errors &Limitations

What are the GPS clock Errors?• A GPS uses an ordinary quartz clock for

measuring time ,which can not measure too small time of a GPS signal from satellite

to GPS receiver. How this Error is corrected? The error is corrected by using mathematical

equations.

Applications Presentor:Muhammad Waqar

Applications

The End

Thanks for your participation.