aircraft navigation- ins / gps

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1 Shanks Inertial Navigation & Global Positioning System Inertial Navigation & Global Positioning System By Shankar Narayan By Shankar Narayan 1 Aircraft Navigation Inertial Navigation & Global Positioning System Inertial Navigation & Global Positioning System Flow of presentation 1 1 What is Navigation 2 2 Inertial Navigation System Concepts 3 3 The Ring Laser Gyro 4 GPS Concepts & Introduction to GPS 5 5 How GPS Works?

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Page 1: Aircraft Navigation- INS / GPS

1

Shanks

Inertial Navigation

&

Global Positioning System

Inertial Navigation

&

Global Positioning System

By Shankar NarayanBy Shankar Narayan

1

Aircraft Navigation

Inertial Navigation

&

Global Positioning System

Inertial Navigation

&

Global Positioning System

Flow of presentation

11 What is Navigation

22 Inertial Navigation System Concepts

33 The Ring Laser Gyro

44 GPS Concepts & Introduction to GPS

55 How GPS Works?

Page 2: Aircraft Navigation- INS / GPS

2

29th August 2009

Navigation Navigation

Navigation is the art of guiding oneself to one’s

desired Destination

For Navigation You need to Know your position

at any instant of time!

3Shanks

ShanksJanuary 23, 2017

Inertial Navigation SystemInertial Navigation System

Presented by

Shankar Narayan

INS conceptsINS concepts

Page 3: Aircraft Navigation- INS / GPS

3

January 23, 2017

What is an Inertial Navigation System

(INS)?

• Every object that is free to move in space has six "degrees of freedom" - or ways it can move.

• There are three linear degrees of freedom (x,y,z) that specify your position and three rotational degrees of freedom (theta (pitch), psi (yaw), and phi (roll)) that specify your attitude.

• If you know these six variables, you know where you are and which way you're pointed

Inertia – inertness, property by which matter continues in existing state of rest

Or uniform motion, unless acted on by external force

Attitude

• Yaw

• Roll

• Pitch

Page 4: Aircraft Navigation- INS / GPS

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January 23, 2017

The six parameters of freedom

A body's actual spatial behavior / movement can be

described with three translatory and three rotary

components.

• : three translatory (x-, y-, z-acceleration) and three rotatory

components (x-, y-, z-angular velocity)

January 23, 2017

Inertial Navigation is accomplished by integrating the output of a set of sensors to compute position, velocity, and attitude.

The sensors used are:

1. Gyros

2. Accelerometers.

Inertial NavigationInertial Navigation

Page 5: Aircraft Navigation- INS / GPS

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January 23, 2017

INS

• The present Inertial Navigation uses 'solid state' systems

consists of expensive laser-gyros and integrated sensor

devices (accelerometers) in MEMS technology (Micro

Electro-Mechanical System).

• Inertial navigation systems (INS) are used in civil and military aviation, cruise missiles, submarines and space technology.

January 23, 2017

What is inertial Measurement Unit?

• An inertial measurement unit, or IMU, is a "clump" of six

inertial sensors. Three linear accelerometers and three

rate gyros make up our IMU. Usually, an IMU also

contains a computational unit to do the position

calculations based off of the sensors

Page 6: Aircraft Navigation- INS / GPS

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ShanksJanuary 23, 2017

LASER

GENERAL INFORMATION

January 23, 2017

LASER

• LIGHT

• AMPLIFICATION BY

• STIMULATED

• EMISSION OF

• RADIATION

STIMULATE = EXITE

• LASER IS A COHERENT SOURCE OF LIGHT

• LASER LIGHT IS MORE DIRECTIONAL, MORE MONOCHROMATIC &

HENCE MORE BRIGHT COMPARED WITH OTHER SOURCES OF

LIGHT.MONOCHROMATIC = SINGLE WAVE LENGTH/COLOR

COHERENT = COSTANT PHASE/CONSISTANT

Spontaneous = occurring without any external cause

Page 7: Aircraft Navigation- INS / GPS

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January 23, 2017

LASER

ShanksJanuary 23, 2017

RING LASER GYROMETER

Page 8: Aircraft Navigation- INS / GPS

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January 23, 2017

RLG PRINCIPLE

January 23, 2017

LASER GYRO

Page 9: Aircraft Navigation- INS / GPS

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January 23, 2017

RLG Block Triangle

Page 10: Aircraft Navigation- INS / GPS

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January 23, 2017

mirror

mirror mirror

mirror

mirror

mirror

ROLL

HEADING (YAW)

PITCH

Page 11: Aircraft Navigation- INS / GPS

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January 23, 2017

RLG PRINCIPLE

January 23, 2017

ADDING OF LASER BEAMS

PRODUCE FRINGES

Page 12: Aircraft Navigation- INS / GPS

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January 23, 2017

MOTION DETECTION

• WHEN NO MOVEMENT – FRINGE PATTERN IS

FIXED.

• WHEN A MOVEMENT IS DETECTED – THE FRINGE

PATTERN MOVES, DEPENDS UPON THE DIRECTION

OF MOTION OF THE GYRO & IS PROPORTIONAL TO

THE RATE OF ROTATION.

January 23, 2017

LASER IN RLG

• TYPE OF LASER USED IS HELIUM / NEON. HENCE

THE COLOUR IS REDDISH ORANGE.

• FREQUENCY FOR LASER = 1000000000000000

CYCLES PER SECOND.

• THE GLASS TUBE IS MADE OF ‘ZERO DUR’ GERMAN

GLASS INCLUDING THE MIRRORS.

Page 13: Aircraft Navigation- INS / GPS

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ShanksJanuary 23, 2017

ACCELERO METERSACCELERO METERS

January 23, 2017

The apparatus to measure

acceleration uses the property of

each physical body to persist in a

state of rest on uniform motion.

This property is called inertia and is

characterised by a force F which,

under acceleration g, moves the

mass in the opposite direction to the

acceleration.

AccelerometerAccelerometer

0 1 2

Mass

0 1 2

Mass

Deflection with 1

unit of acceleration

0 1 2

Mass

Deflection with 2

units of acceleration

F = m γ

Page 14: Aircraft Navigation- INS / GPS

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January 23, 2017

The measurement instruments are

called accelerometers and may be

either linear or pendular, this later type

at present being the most widely used.

Under the effect of an acceleration g

of 20 m/s2, the mass moves along

measurement axis. The marked

graduations allowed the value of the

acceleration to be obtained that is 20

m/s2.

20 0 -20

Measurement

axis

γγγγ = 20 m/s²

LINEAR ACCELEROMETER

(principle)

20 0

Measurement

axis

-20

PENDULAR ACCELEROMETER

(principle)

AccelerometerAccelerometer

January 23, 2017

In the case of a pendulum accelerometer,the influence of the earth gravity takes

action as soon as the pendulum leaves its point of equilibrium even if the sensitive

axis is perpendicular to the force of attraction g.

The accelerometer measurement is then erroneous. In order to cancel out this

influence the pendulum must be made to work around its point of equilibrium.

γγγγ = 20 m/s²

0

Sensitive

axis

PENDULAR ACCELEROMETER

g

γγγγ

g

AccelerometerAccelerometer

Page 15: Aircraft Navigation- INS / GPS

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January 23, 2017

AccelerometerAccelerometer

January 23, 2017

• Accelerometer Used Is Pendulum Type Accelerometer.

• Displacement Of The Pendulum Depends On

Acceleration.

• From The Displacement Value Of The Pendulum,

Acceleration Can Be Computed.

AccelerometerAccelerometer

Page 16: Aircraft Navigation- INS / GPS

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January 23, 2017

ACCELEROMETER PRINCIPLE

FLEXIBL

E SHADE

MAGNETIC

DEVICE

DETECTORS

COILS

PENULUM

WITH HINGE

January 23, 2017

ACCELEROMETER OPERATION

With No Motion, Pendulum Is Centered, And The Capacitor Bridge Is Balanced

When A Motion Is Detected,the Pendulum Is Displaced And The Bridge Is No Longer Balanced. So A Current Is Induced Proportional To The Displacement Of The Pendulum

Pendulum Is Bought Back To Its Null Point By Means Of A Mechanism Which Generates A Field In Opposition To The Pendulum Movement.

The Value Of The Current Necessary For The Mechanism To Keep The Pendulum At Zero Represents The Measured Acceleration

Page 17: Aircraft Navigation- INS / GPS

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Shanks

GLOBAL POSITIONING SYSTEMGLOBAL POSITIONING SYSTEM.. In everyday life 5

Presented by Shankar Narayan

GPSGPSConceptsConcepts

Position of any point on earthPosition of any point on earth

Any location on Earth is described

by three numbers--its latitude

its longitude and its altitude.

If a pilot or a ship's captain

wants to specify position

on a map, these are

the "coordinates" they would use.

Any location on Earth is described

by three numbers--its latitude

its longitude and its altitude.

If a pilot or a ship's captain

wants to specify position

on a map, these are

the "coordinates" they would use.

Position

LatitudeLatitude LongitudeLongitude AltitudeAltitude

GeographicalCoordinates & Altitude

GeographicalCoordinates & Altitude

*

Page 18: Aircraft Navigation- INS / GPS

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LatitudeLatitude

• On a globe of the Earth, lines

of latitude are circles of

different size. The longest is

the equator, whose latitude is

zero, while at the poles--at

latitudes 90° north and 90°

south (or -90°) the circles

shrink to a point. To specify the latitude of some

point P on the surface, draw

the radius OP to that point.

Then the elevation angle of

that point above the equator

is its latitude λ--northern

latitude if north of the equator,

southern (or negative) latitude

if south of it.

LongitudeLongitude

• On the globe, lines of constant

longitude ("meridians") extend

from pole to pole, like the

segment boundaries on a

peeled orange.

• For historical reasons, the

meridian passing the old Royal

Astronomical Observatory in

Greenwich, England, is the

one chosen as zero longitude

Page 19: Aircraft Navigation- INS / GPS

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29th August 2009

Latitude/ Longitude & DirectionsLatitude/ Longitude & Directions

Radius of Earth = 6 378.1 kilometersRadius of Earth = 6 378.1 kilometers

3737ShanksShanks Training & Development Institute, HAL, NasikTraining & Development Institute, HAL, Nasik

*

29th August 2009

latitude

l

o

n

g

i

t

u

d

e

20 degree

73

de

gr

ee

73deg. 54 min 52 sec

ojhar

20 deg. O7 min 22 sec

Shanks

38

Page 20: Aircraft Navigation- INS / GPS

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The Longitude ( Meridian)The Longitude ( Meridian)

• A lines of longitude is also called a meridian, derived from the Latin,

from meri, a variation of "medius" which denotes "middle", and

diem, meaning "day." The word once meant "noon", and times of

the day before noon were known as "ante meridian", while times

after it were "post meridian." Today's abbreviations a.m. and p.m.

come from these terms, and the Sun at noon was said to be

"passing meridian". All points on the same line of longitude

experienced noon (and any other hour) at the same time and were

therefore said to be on the same "meridian line", which became

"meridian" for short.

• Longitudes are measured from zero to 180° east and 180° west

(or -180°), and both 180-degree longitudes share the same line,

in the middle of the Pacific Ocean

Local & Universal TimeLocal & Universal Time

• Local time is actually a measure of the position of the Sun relative to a locality. At 12 noon local time the Sun passes to the south and is furthest from the horizon (northern hemisphere). Somewhere around 6 am it rises, and around 6 pm it sets. Local time is what you and I use to regulate our lives locally, our work times, meals and sleep-times.

• universal time (UT), which can be defined (with some slight imprecision, no concern here) as the local time in Greenwich, England, at the zero meridian. That is, a single agreed-on clock, marking time world-wide, not tied to our locality. Astronomers, astronauts and people dealing with satellite data may need a time schedule which is the same everywhere, not tied to a locality or time zone. The Greenwich mean time, the astronomical time at Greenwich (averaged over the year) is generally used here. It is sometimes called Universal Time (UT).

Page 21: Aircraft Navigation- INS / GPS

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International Date LineInternational Date Line

• International date line has been established--most of it

following the 180th meridian--where by common

agreement, whenever we cross it the date advances one

day (going west) or goes back one day (going east).

That line passes the Bering Strait between Alaska and

Siberia, which thus have different dates, but for most of

its course it runs in mid-ocean and does not

inconvenience any local time keeping.

What is GPS ?Global Positioning System

(GPS) is a satellite

Navigation System

which is invented

and Controlled

by the US

Department

of Defense (DOD)

Global Positioning System

(GPS) is a satellite

Navigation System

which is invented

and Controlled

by the US

Department

of Defense (DOD)

Page 22: Aircraft Navigation- INS / GPS

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Global positioning systemGlobal positioning system

• GPS provides specially coded satellite signals.

• These Signals can be processed in a GPS

Receiver.

• The Receiver after processing, outputs highly

accurate - position , velocity, time and altitude

information, to the GPS users around the world.

GPS Uses in Everyday lifeGPS Uses in Everyday life

• Developed for military use( ships, aircrafts..)

• Use in tunnel construction –English # French

• Used in cars, Buses, Trains, to monitor Position

• Help save life- Use in emergency Vehicles

• Moving Map displays in vehicles Guided by GPS

• Used in Surveying, Wildlife management.

• GPS equipped Balloons used to find explore the ozone layer.

• Explorers use GPS extensively

*

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GPS Systems of the World

• GLONASS ( Russian) – To be completed by 2010

Global Navigation Satellite System

• NAVSTAR ( American)- Completed

Navigation System by Timing and Ranging

• GALILEO (England) – To be completed by 2020

*

The program was created by the US Department of defense (DOD) in 1973.

The First GPS satellite, Block I developmental model was launched in February 1978.

For Global operation of GPS System, a constellation of 24 satellites (Minimum) is required

Birth of NAVSTAR GPS

*

Page 24: Aircraft Navigation- INS / GPS

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The 24 satellites constellation mile stone was achieved

in June 1993

The system gained fame ‘desert storm’ by providing

unprecedented navigational accuracy for allied air and

ground forces.

Global positioning systemGlobal positioning system

‘The Global Positioning System Fully

Operational, This declaration came from US

Air force on July 17th 1995.

Shanks

The Three

Segments

of GPS

The Three

Segments

of GPS

GPSGPS

4848

Page 25: Aircraft Navigation- INS / GPS

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GPS consists of Three SegmentsGPS consists of Three Segments

Control

segment

Control

segment

consists of a master

control station,

5 monitoring

stations, three ground

antennas & a

Pre launch check

out station

SpaceSegmentSpaceSegment

consists of 24

satellites

User SegmentUser

Segment

consists of various

GPS receivers

NAVSTAR Global Positioning System

*

Control segmentControl segment

5 monitoring stations which passively track & collect ranging data from all satellites in view.

A master control station which processes the satellite ranging data to determine satellite orbits and update the navigation message for each satellite.

3 ground antennas which transmit the updated navigation message to each satellite .

A pre launch station which supports the satellite pre-launch compatibility tests and serves as a fourth ground antenna when necessary.

Page 26: Aircraft Navigation- INS / GPS

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29th August 2009

Control SegmentControl Segment

The GPS system used is American NAVSTAR ( NAVigation System by

Timing And Ranging) system

1 master control station, 5 monitoring stations, 1 pre launch station,3 ground

antenna

AFB- AIRFORCE BASE

Note :-all the stations are under the control of U S. Territory &

They are all positioned near the equator

Shanks

51

Space segmentSpace segment

• The space segment consists of 24

operational satellites plus 3 spares

Page 27: Aircraft Navigation- INS / GPS

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The Space Segment

Satellite 12 hr. period ..Satellite 12 hr. period ..

24+3

Satellites

24+3

Satellites

Space segment

4 satellite

In each

Orbit

4 satellite

In each

Orbit

Six

Orbits

Six

Orbits

20,200 KM

From

earth

20,200 KM

From

earthOrbit

inclination

= 55 deg.

Orbit

inclination

= 55 deg.KNAVSTAR System of GPSKNAVSTAR System of GPS

hrs

Satellite

makes two

rounds in 24

hrs

*

*

GPS ConstellationGPS Constellation54

Page 28: Aircraft Navigation- INS / GPS

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GPS OrbitsGPS Orbits

12 Hour Period

ShanksShanks

5555ShanksShanks

*

Satellite Vehicle No. 27Satellite Vehicle No. 27

Sensors

Sensors

Shanks

*

Page 29: Aircraft Navigation- INS / GPS

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-45 deg.lat

+ 45 deg. lat

0 deg. lat

+ 70 deg. lat

- 70 deg. lat

NO SV COVERAGE IN THIS

REGION

NO SV COVERAGE IN THIS

REGION

A satellite vehicle is not

stable in the cone of +/ -

70 deg

Its not possible to apply

correction in this cone.

GPS GIVES ERRORS FOR LAT

> +/- 70 DEG.

GPS GIVES ERRORS FOR LAT

> +/- 70 DEG.

29th August 2009

GPS constellation in operationGPS constellation in operation

COMPLETE COVERAGE WITH A MINIMUM OF 5 SV IN VIEW ALL AROUND THE WORLD

EXCEPT NO COVERAGE AT LAT >+ - 70 Deg.

Shanks

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User SegmentUser Segment

USER SEGMENTUSER SEGMENT

The user segment consists of receivers and associated support equipment

Receiver processes signals transmitted by the satellites and Finds:

1. Its Distance from Satellite

2. And calculates Lat, Long, Altitude

Page 31: Aircraft Navigation- INS / GPS

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Hand held GPS ReceiverHand held GPS Receiver

General Information related to GPS General Information related to GPS

Page 32: Aircraft Navigation- INS / GPS

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CARRIER FREQUENCYCARRIER FREQUENCY

GPS Carrier frequency L1& L2 : 1575.42 MHz and

1277.60 MHz .

These Frequencies are necessary to travel through

ionosphere and troposphere.

SPS – Std. Positioning Service PPS - Precise Positioning Service

SPS has access to codeless L1 signal. (We are SPS users)

PPS user has access to all signals on L1 & L2 and to the

full accuracy of GPS ( only US)

PPS users must have the classified algorithms and the

classified key to remove errors

VELOCITY MEASUREMENTVELOCITY MEASUREMENT

• Velocity is measured using Doppler effect through software.

• The received frequency appears increased as the satellite comes towards the receiver

• Decreases as it recedes from the user.

Page 33: Aircraft Navigation- INS / GPS

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EPHEMERISEPHEMERIS

• In a receiver complete check of ephemeris and

storage normally takes 12.5 min to 25 min Max

• The predictions of current satellite positions

transmitted to the user in the data message.

(Orbital data of a satellite vehicle.)

•Ephemeris last for one week

ALMANACALMANAC

• A data file that contains orbit information on all

satellites, clock corrections, and atmospheric

delay parameters.

• It is transmitted by each GPS satellite in order to

facilitate rapid satellite vehicle data acquisition by

GPS receivers.

Page 34: Aircraft Navigation- INS / GPS

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GPS -NOTEGPS -NOTE

• Velocity of satellite is approximately 30 km /sec.

• Clock frequency is 100mhz.

• Lat/long calculation is done at the speed of 1 hz.

How GPS Works?How GPS Works?

Page 35: Aircraft Navigation- INS / GPS

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Position in Space/ on EarthPosition in Space/ on Earth

Shanks

Position in Space/ on EarthPosition in Space/ on Earth

Page 36: Aircraft Navigation- INS / GPS

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Aircraft Position determinationAircraft Position determination

Aircraft position in space is found by computing a/cs distance from 4 satellites

Also all those 4 satellites position from the earth centre is known.

By knowing above two parameters a/cs position from earth centre is computed.

From the earth model WGS- 84, comparing the above results , latitude. Longitude and altitude can be found.

*

29th August 2009

TriangulationTriangulation

TRIANGULATE - MEASURING AND MAP OUT BY DIVIDING IT INTO TRIANGLES

Radius of Earth = 6 378.1 kilometersRadius of Earth = 6 378.1 kilometers

Page 37: Aircraft Navigation- INS / GPS

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Result of TriangulationResult of Triangulation

Shanks

Earth

Result of TriangulationResult of Triangulation

Shanks

Earth

Page 38: Aircraft Navigation- INS / GPS

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LATITUDE / LONGITUDE & ALTITUDELATITUDE / LONGITUDE & ALTITUDE

Shanks*

Shanks

Triangulation

Summary

Triangulation

Summary

GPS

7676

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29th August 2009 7777ShanksShanks

29th August 2009 7878ShanksShanks

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29th August 2009 7979

29th August 2009 80Shanks

Page 41: Aircraft Navigation- INS / GPS

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29th August 2009

TWO MEASUREMENTS PUT US

SOMEWHERE IN THIS CIRCLE

TWO MEASUREMENTS PUT US

SOMEWHERE IN THIS CIRCLE

ONE OF THESE TWO

POINTS IS THE

ACCURATE LOCATION

A THIRD SATELLITE

PUTS US AT EITHER OF

TWO POINTS

Shanks

SummarySummary

• Thus with the information from four satellites, the Position of the GPS

receiver user is fixed in space or on earth with respect to satellites.

• Triangulation of the above results gives the position with respect to the

centre of earth.

• The altitude of the GPS receiver user is obtained by Subtracting the

radius of earth from the earth centre distance.

• The triangulation result when superimposed on the WGS – 84

software model, gives the latitude & Longitude of the GPS user.

• Thus the GPS user will know his position accurately with respect to

earth. In terms of latitude, Longitude & Altitude.

Page 42: Aircraft Navigation- INS / GPS

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January 23, 2017

Thank YouThank You

[email protected]

9405183808

www.shankarnarayan.co.in