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GPS And Applications Seminar Report ‘04
Chapter 1
INTRODUCTION
The Global Positioning System, usually called GPS (the US
military refers to it as NAVSTAR), is an intermediate circular orbit (!")
satellite na#igation system used for determining one$s %recise location and
%ro#iding a highly accurate time reference almost any&here on 'arth or in
'arth orbit(
The first of )* satellites that form the current GPS constellation
(+loc, ) &as %laced into orbit on -ebruary .*, ./0/( The 12th GPS
satellite since the beginning in ./30 &as launched 4arch )., )22* aboard a
5elta roc,et

1.1 GPS HISTORY
The initial conce%t of GPS began to ta,e form soon after the
launch of S%utni, in ./13( 6(((( Some scientists and engineers reali7ed that
radio transmissions from a satellite in a &ell8defined orbit could indicate the
%osition of a recei#er on the ground9 This ,no&ledge resulted in the U(S(
Na#y$s de#elo%ment and use of the 9transit9 system in the ./:2$s( This
system, ho&e#er, %ro#ed to be cumbersome to use and limited in terms of
%ositioning accuracy(
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GPS And Applications Seminar Report ‘04
-igure .
Starting in the mid8./32s the U(S( 5e%artment of 5efense
(5"5) began the construction of today$s GPS and has funded, o%erated, and
maintained control of the system it de#elo%ed( '#entually ;.) billion dollars
&ould ta,e GPS from conce%t to com%letion( -ull "%erational !a%acity
(-"!) of GPS &as reached on <uly .3, .//1 (U(S(!(G(, .//:, &&&)( At one
%oint GPS &as renamed NAVSTAR( This name, ho&e#er, seems to be
regularly ignored by system users and others( Although the %rimary use of
GPS &as thought to be for classified military o%erations, %ro#isions &ere
made for ci#ilian use of the system( National security reasons, ho&e#er,
&ould re=uire that ci#ilian access to accurate %ositioning be intentionally
degraded(

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GPS And Applications Seminar Report ‘04
Chapter 2
GPS ELEMENTS
GPS &as designed as a system of radio na#igation that utili7es
9ranging9 88 the measurement of distances to se#eral satellites 88 for
determining location on ground, sea, or in the air( The system basically
&or,s by using radio fre=uencies for the broadcast of satellite %ositions and
time( >ith an antenna and recei#er a user can access these radio signals and
%rocess the information contained &ithin to determine the 9range9, or
distance, to the satellites( Such distances re%resent the radius of an imaginary
s%here surrounding each satellite( >ith four or more ,no&n satellite
%ositions the users$ %rocessor can determine a single intersection of these
s%heres and thus the %ositions of the recei#er ( The system is generally
com%rised of three segments?
.( The s%ace segment
)( The control segment
@( The user segment

2.1 SPACE SEGMENT
The s%ace segment consists of )* satellites, each in its o&n orbit
..,222 nautical miles abo#e the 'arth( The user segment consists of
recei#ers, &hich you can hold in usersA hands or mount in usersA #ehicle(
The control segment consists of ground stations located around the &orld
that ma,e sure the satellites are &or,ing %ro%erly
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GPS And Applications Seminar Report ‘04
2.1.1 Orbit
-igure )
The GPS s%ace segment uses a total of )* satellites in a
constellation of siB orbiting %lanes( This configuration %ro#ides for at least
four e=ually8 s%aced satellites &ithin each of the siB orbital %lanes( The
orbital %ath is continuous in relation to the earth, meaning that a satellite$s
orbit &ill follo& the same %ath on the earth &ith each orbit( At .2,/22nm
()2,)22,m) GPS satellites are able to com%lete one orbit around the earth
e#ery .) hours( GPS satellites orbit at a 118degree inclination to the
e=uatorial %lane( This s%ace segment configuration %ro#ides for a minimum
of 1 satellites to be in #ie& from any %lace on earth, fulfilling the necessary
four needed for three8dimensional %ositioning(
2.1.2 Freqe!"ie#
The GPS satellite, li,e other telecommunication satellites, uses
radio signal transmission for distribution of data used in %ositioning
com%utations( 'ach satellite continuously transmits a com%osite s%read
s%ectrum signal on t&o C band fre=uencies( C. transmits at .131(*) 4D7
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GPS And Applications Seminar Report ‘04
and C) transmits at .))3(:24D7( +oth carrier fre=uencies are %hase8
modulated &ith the Precise code (P8code)( The C. carrier is additionally
%hase8modulated &ith the !oarseEAc=uisition8code( A Na#igation 4essage
is also modulated on the C.8 !EA8code signal( 'ach satellite transmits a
uni=ue code, allo&ing the recei#er to identify the different code of each
satellite(

2.1.$ C%&e#
-irst obser#ation of these codes &ould suggest that they are
random( n fact, all GPS codes are Pseudo Random Noise (PRN) codes by
design( >ith the a%%ro%riate recei#er one can see that these codes actually
follo& a &ell 8 defined, %redictable se=uence( Recei#ing e=ui%ment is used
to find the highest correlation bet&een a ,no&n GPS code and the radio
transmission of that code recei#ed by the user( "nce a correlation is found
the user is able to find the lag time bet&een the ,no&n time of code
broadcast and the time the code &as recei#ed by the user( The lag is the time
it ta,es the code to get from the GPS satellite to the user$s recei#er( This time
can then be used to determine the distance bet&een the ,no&n satellite
%osition and the user %osition(
The broadcast of !oarse Ac=uisition !ode (!EA8code) &as
designed for ci#ilian a%%lications of the GPS( The !EA8code is a#ailable to
#irtually anybody at any time, %ro#ided they ha#e the right e=ui%ment(
Gi#en the %otential for harmful a%%lications of the GPS, the
designers of the system built into the !EA8codes &hat is ,no&n as selecti#e
a#ailability( Selecti#e a#ailability is an intentional inaccuracy in a satellite$s
onboard cloc, that changes o#er time( This intentional inaccuracy is ,no&n
as cloc, dither and is classified GPS information( The result of cloc, dither
is essentially a degradation of na#igational accuracy(
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GPS And Applications Seminar Report ‘04
The broadcast of Precise8code (P8codes) &as designed for
military a%%lications and is generally restricted to authori7ed %ersonnel and
organi7ations( The P8code is a .2 4D7 PRN code carried on both C. and
C)( -or additional security the Anti8S%oofing (A8S) mode can be engaged(

The Na#igation 4essage is carried on the C. fre=uency as 12D7
signal( This signal carries information concerning the satellite orbit %osition,
cloc, corrections and other system %arameters( GPS authorities may also
degrade and falsify this information in an effort to limit ci#ilian access to
eBtremely accurate na#igational techni=ues(
2.1.' Ti(e a!& p#e&%)ra!*e#
"n board each GPS satellite is a highly accurate atomic cloc,(
9These cloc,s are by nature #ery stable (they might gain or lose a second in
@2,222 years)(9 n order for accurate measurements of time to ha%%en
bet&een the GPS and the user, nearly eBact synchroni7ation is needed
bet&een satellite time and user time( Since the user$s recei#er is generally an
inaccurate time%iece eBact synchroni7ation is not easily a#ailable(
Accurate %ositioning can be achie#ed, ho&e#er, by using
%seudo8 ranges( A %seudo8range is an inaccurate distance established
bet&een a satellite and a recei#er( 5es%ite this inaccuracy, determining a
distance bet&een the recei#er and a ,no&n satellite location %ro#ides a
s%here of reference( The radius of this s%here of reference is e=ual to the
%seudo8range established bet&een the GPS satellite and the recei#ing unit(
>ith four s%heres of reference from four different satellites a user has the
s%atial %ositions needed for three dimensional %ositioning( The intersection
%oint of these four s%heres &ill result in an inaccurate location for the
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GPS And Applications Seminar Report ‘04
recei#er( To gain a more accurate reading the user can adFust for the initial
time inaccuracy by lo&ering or raising the amount of time lag originally
determined( >ith time adFustments, additional com%utations can result in
more accurate distances and thus greater accuracy in %ositioning(
2.2 CONTROL SEGMENT
-igure @
The control or ground segment of the GPS consists of unmanned
monitor stations located around the &orld(Da&aii and G&aFalein in the
Pacific "ceanH 5iego Garcia in the ndian "ceanH Ascension sland in the
Atlantic "ceanH and !olorado S%rings, !olorado)( The GPS 4aster !ontrol
Station (4!S) is located on the -alcon Air -orce +ase in !olorado( The
monitoring stations trac, any GPS satellites in #ie& and collect ranging
information from the radio broadcast of each #ie&able satellite( As
information is collected it is sent bac, to master control for %rocessing(
4aster control uses this data to create a na#igation message containing
%recise orbit %ositions, time adFustments, and system %arameters( 4onitoring
stations &ith u%lin, ca%abilities can then transmit the na#igation message
bac, u% to the a%%ro%riate GPS satellite( Subsets of this na#igation message
are rebroadcast for use by recei#ing e=ui%ment(
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GPS And Applications Seminar Report ‘04
2.$ USER SEGMENT
-igure *
The user segment consists of the a%%ro%riate antenna, recei#er,
and %rocessor used to gain access to GPS( >ith this e=ui%ment a userAs can
recei#e GPS transmissions and com%ute their %recise %osition, #elocity, and
time( This segment includes a #ariety of %roducts used for different
a%%lications? marine na#igation, ma% sur#eying, trac,ing #ehicles, search
and rescue, and many others(
2.$.1 SPS + Sta!&ar& P%#iti%!i!* Ser,i"e
Standard Positioning Ser#ice (SPS) is a free ser#ice a#ailable to
ci#ilian users of GPS( SPS is broadcast from the GPS constellation as !EA8
code on the C. fre=uency( t is designed around a limited standard of
%osition and timing accuracy that is a#ailable to &orld&ide users &ithout
restrictions( The accuracy (and the intentional degradation through selecti#e
a#ailability) of SPS is established by the U(S( 5e%artment of 5efense based
on national security interest( Accuracy of SPS &as initially designed to be
&ithin .22 hori7ontal meters( !hanges in consumer end recei#er8%rocessing
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GPS And Applications Seminar Report ‘04
technology, ho&e#er, ha#e increased the degree of accuracy that can be
achie#ed &ith SPS(
2.$.2 PPS + Pre"i#e P%#iti%!i!* Ser,i"e
+ecause of itAs greater accuracy the Precise Positioning Ser#ice
(PPS) is a#ailable only to U(S( and allied military, some U(S( Go#ernment
agencies, and authori7ed ci#ilian users( !ry%togra%hic e=ui%ment and ,eys
and s%ecially e=ui%%ed recei#ers are needed for use of the PPS( Dori7ontal
accuracy is %redictable to )) meters(

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GPS And Applications Seminar Report ‘04
Chapter III
TRILATERATION)THE -OR.ING PRINCIPLE OF
OPERATION
A GPS recei#erAs Fob is to locate four or more of these satellites,
figure out the distance to each, and use this information to deduce its o&n
location( This o%eration is based on a sim%le mathematical %rinci%le called
trilateration(Trilateration is based on the fact that a body cannot occu%y t&o
%ositions in s%ace simultaneously( Trilateration can be done in t&o &ays
.( )85 Trilateration
)( @85trilateration

$.1. 2)D TRILATERATION
f an obFect is :)1 miles from A it could be any&here on a circle
around A that has a radius of :)1 miles(

-igure 1
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GPS And Applications Seminar Report ‘04
And if the obFect is :/2 miles from + and this information is
combined &ith the former information, &e ha#e t&o circles that intersect to
get the %osition &hich results in t&o %ositions And &ith a third information
&e can clearly s%ot the eBact %osition This same conce%t &or,s in three8
dimensional s%ace, as &ell, but has s%heres instead of circles(
$.2. $)D TRILATERATION
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GPS And Applications Seminar Report ‘04

Fi*re /
Fundamentally, three-dimensional trilateration isn't much different
from two-dimensional trilateration, but it's a little trickier to visualize. Imagine
the radii from the examples in the last section going off in all directions. o
instead of a series of circles, you get a series of spheres.
f a %erson ,no& he is .2 miles from satellite A in the s,y, he could be
any&here on the surface of a huge, imaginary s%here &ith a .28mile radius(
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GPS And Applications Seminar Report ‘04
f he also ,no&s he is .1 miles from satellite + he can o#erla% the first
s%here &ith another, larger s%here( The s%heres intersect in a %erfect circle(
f he ,no&s the distance to a third satellite, he gets the third s%here, &hich
intersects &ith this circle at t&o %oints(
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GPS And Applications Seminar Report ‘04
The 'arth itself can act as a fourth s%here 88 only one of the t&o
%ossible %oints &ill actually be on the surface of the %lanet, so you can
eliminate the one in s%ace( Recei#ers generally loo, to four or more
satellites, ho&e#er, to im%ro#e accuracy and %ro#ide %recise altitude
information( n order to ma,e this sim%le calculation, then, the GPS recei#er
has to ,no& t&o things?
• The location of at least three satellites abo#e him
• The distance bet&een he and each of those satellites
The GPS recei#er figures both of these things out by analy7ing
high8fre=uency, lo&8%o&er radio signals from the GPS satellites( +etter
units ha#e multi%le recei#ers, so they can %ic, u% signals from se#eral
satellites simultaneously(
Radio &a#es are electromagnetic energy, &hich means they
tra#el at the s%eed of light (about .0:,222 miles %er second, @22,222 ,m %er
second in a #acuum)( The recei#er can figure out ho& far the signal has
tra#eled by timing ho& long it too, the signal to arri#e(
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GPS And Applications Seminar Report ‘04
Chapter I0
MEASURING DISTANCE
-igure 3
.( 5istance to a satellite is determined by measuring ho& long a
radio signal ta,es to reach us from that satellite(
)( To ma,e the measurement &e assume that both the satellite and
our recei#er are generating the same %seudo8random codes at
eBactly the same time(
@( +y com%aring ho& late the satellite$s %seudo8random code
a%%ears com%ared to our recei#er$s code, &e determine ho& long
it too, to reach us(
*( 4ulti%ly that tra#el time by the s%eed of light and you$#e got
distance(
At a %articular time, the satellite begins transmitting a long,
digital %attern called a %seudo8random code( The recei#er begins running the
same digital %attern also eBactly at midnight( >hen the satellite$s signal
reaches the recei#er, its transmission of the %attern &ill lag a bit behind the
recei#er$s %laying of the %attern(
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GPS And Applications Seminar Report ‘04
The length of the delay is e=ual to the signal$s tra#el time( The
recei#er multi%lies this time by the s%eed of light to determine ho& far the
signal tra#eled( Assuming the signal tra#eled in a straight line, this is the
distance from recei#er to satellite( n order to ma,e this measurement, the
recei#er and satellite both need cloc,s that can be synchroni7ed do&n to the
nanosecond( To ma,e a satellite %ositioning system using only synchroni7ed
cloc,s, you &ould need to ha#e atomic cloc,s not only on all the satellites,
but also in the recei#er itself( +ut atomic cloc,s cost are too eB%ensi#e for
e#eryday consumer use(
The Global Positioning System has a cle#er, effecti#e solution to
this %roblem( '#ery satellite contains an eB%ensi#e atomic cloc,, but the
recei#er itself uses an ordinary =uart7 cloc,, &hich it constantly resets( n a
nutshell, the recei#er loo,s at incoming signals from four or more satellites
and gauges its o&n inaccuracy(
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GPS And Applications Seminar Report ‘04
Chapter 0
SOURCES OF GPS MEASUREMENT ERRORS
deally, GPS recei#ers &ould easily be able to con#ert the !EA
and P(I)8code measurements into accurate %ositions( Do&e#er, a system
&ith such com%leBity lea#es many o%enings for errors to affect the
measurements( The follo&ing are se#eral causes of error in GPS
measurements(
-igure 0
1.1. CLOC.S
+oth GPS satellites and recei#ers are %rone to timing errors(
Satellites often %ossess cesium atomic cloc,s( Ground stations throughout
the &orld monitor the satellites to ensure that the atomic cloc,s are accurate(
Recei#er cloc, error is un,no&n and often de%ends on the oscillator
%ro#ided &ithin the unit( Do&e#er, it can be calculated and then eliminated
once the recei#er is trac,ing at least four satellites(
1.2 IONOSPHERE
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GPS And Applications Seminar Report ‘04
The ionos%here is one of the leading causes of GPS error( The
s%eed of light #aries due to atmos%heric conditions( As a result, errors
greater than .2 meters may arise( To com%ensate for these errors, the second
fre=uency band C) &as %ro#ided( +y com%aring the %hase difference
bet&een the C. and C) signals, the error caused by the ionos%here can be
calculated and eliminated(
1.$ MULTIPATH
The antenna recei#es not only direct GPS signals, but also
multi%ath signals? reflections of the radio signals off the ground andEor
surrounding structures (buildings, canyon &alls, etc)( -or long multi%ath
signals, the recei#er itself can filter the signals out( -or shorter multi%ath
signals that result from reflections from the ground, s%ecial antenna features
may be used such as a ground %lane, or a cho,e ring antenna( Shorter
multi%ath signals from ground reflections can often be #ery close to the
direct signals, and can greatly reduce %recision(
1.' SELECTI0E A0AILA2ILITY
n the %ast, the ci#ilian signal &as degraded, and a more accurate
Precise Positioning Ser#ice &as a#ailable only to the United States military,
its allies and other, mostly go#ernment users( Do&e#er, on 4ay ., )222,
then US President +ill !linton announced that this 9Selecti#e A#ailability9
&ould be turned off, and so no& all users enFoy nearly the same le#el of
access, allo&ing a %recision of %osition determination of less than )2 meters(
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GPS And Applications Seminar Report ‘04
Chapter 0I
TECHNI3UES TO IMPRO0E GPS ACCURACY
'#en if there are many %roblems %ertaining to accuracy due to
errors in measurement,the accuracy of GPS can be im%ro#ed in a number of
&ays?

/.1. DIFFERENTIAL GPS 4DGPS5 hel%s correct these errors( The
basic idea is to gauge GPS inaccuracy at a stationary recei#er station &ith a
,no&n location( Since the 5GPS hard&are at the station already ,no&s its
o&n %osition, it can easily calculate its recei#er$s inaccuracy( The station
then broadcasts a radio signal to all 5GPS8e=ui%%ed recei#ers in the area,
%ro#iding signal correction information for that area( n general, access to
this correction information ma,es 5GPS recei#ers much more accurate than
ordinary recei#ers(
5ifferential correction techni=ues are used to enhance the
=uality of location data gathered using global %ositioning system (GPS)
recei#ers( 5ifferential correction can be a%%lied in real8time directly in the
field or &hen %ost %rocessing data in the office( Although both methods are
based on the same underlying %rinci%les, each accesses different data
sources and achie#es different le#els of accuracy( !ombining both methods
%ro#ides fleBibility during data collection and im%ro#es data integrity(
The underlying %remise of differential GPS (5GPS) is that any
t&o recei#ers that are relati#ely close together &ill eB%erience similar
atmos%heric errors( 5GPS re=uires that a GPS recei#er be set u% on a
%recisely ,no&n location( This GPS recei#er is the base or reference station(
The base station recei#er calculates its %osition based on satellite signals and
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GPS And Applications Seminar Report ‘04
com%ares this location to the ,no&n location( The difference is a%%lied to
the GPS data recorded by the second GPS recei#er, &hich is ,no&n as the
ro#ing recei#er( The corrected information can be a%%lied to data from the
ro#ing recei#er in real time in the field using radio signals or through %ost
%rocessing after data ca%ture using s%ecial %rocessing soft&are(
/.2. E6PLOITATION OF DGPS FOR GUIDANCE
ENHANCEMENT 4EDGE5 is an effort to integrate 5GPS into %recision
guided munitions such as the <oint 5irect Attac, 4unition (<5A4)(
/.$. THE -IDE)AREA AUGMENTATION SYSTEM 4-AAS5.
>ide Area Augmentation System is the latest method of
%ro#iding better accuracy from the GPS constellation( t is similar in
%rinci%le the 5GPS ca%ability that is built into all Garmin and many other
units eBce%t that a second recei#er is not re=uired( nstead of a beacon
recei#er the correction data is sent #ia a geo8stationary satellite and is
decoded by one of the regular channels already %resent in the GPS recei#er(
Thus one of the .) channels can be designated to decode regular GPS
signals or can be used to decode the >AAS data( Actually, as currently
im%lemented, &hen >AAS is enabled t&o channels &ill be dedicated to
>AAS( >hile >AAS is the name of the im%lementation of this technology
in the US the system is intended for &orld&ide use( The generic name for
>AAS is S+AS (S%ace +ased Augmentation System) or >A5GPS (>ide
Area 5ifferential GPS)(
The &ay this &or,s is that a set of ground stations all o#er the
US collect correction data relati#e to the area of the country they are located
in( The entire data is then %ac,aged together, analy7ed, con#erted to a set of
correction data by a master station and then u%loaded to the geo8stationary
satellite, &hich in turn transmits the data do&n to the local GPS recei#er(
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GPS And Applications Seminar Report ‘04
The GPS recei#er then figures out &hich data is a%%licable to its current
location and then a%%lies the a%%ro%riate corrections to the recei#er( Similar
systems are being set u% in other areas of the &orld but they are not ye n
addition to correction information the ground stations can also identify a
GPS satellite that is not &or,ing &ithin s%ecification thereby im%ro#ing the
integrity of the system for a#iation use(
/.'. A LOCAL)AREA AUGMENTATION SYSTEM 4LAAS5. This
is similar to >AAS, in that similar correction data are used( +ut in this case,
the correction data are transmitted from a local source, ty%ically at an air%ort
or another location &here accurate %ositioning is needed( These correction
data are ty%ically useful for only about a thirty to fifty ,ilometer radius
around the transmitter(
/.1. -IDE AREA GPS ENHANCEMENT 4-AGE5 is an attem%t to
im%ro#e GPS accuracy by %ro#iding more accurate satellite cloc, and
e%hemeris (orbital) data to s%ecially8e=ui%%ed recei#ers(
/./. RELATI0E .INEMATIC POSITIONING 4R.P5 is another
a%%roach for a %recise GPS8based %ositioning system( n this a%%roach,
accurate determinination of range signal can be resol#ed to an accuracy of
less than .2 centimeters( This is done by resol#ing number of cycles in
&hich the signal is transmitted and recei#ed by the recei#er( This can be
accom%lished by using a combination of differential GPS (5GPS) correction
data, transmitting GPS signal %hase information and ambiguity resolution
techni=ues #ia statistical tests 8 %ossibly &ith %rocessing in real8time (real8
time ,inematic %ositioning

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GPS And Applications Seminar Report ‘04
Chapter 0II
APPLICATIONS
7.1. MILITARY
Army %eo%le &ere the first to use and they themsel#es are the
intensi#e users( Their use is incommensurable
7.1.1. Gi&a!"e
-igure /
The %rimary military %ur%ose is to allo& im%ro#ed command
and control of forces through an enhanced ability to accurately s%ecify target
locations for cruise missiles or troo%s( The satellites also carry nuclear
detonation detectors(
-or eBam%le U(S( 4arines used GPS8guided %arachutes to carry
su%%lies to soldiers in an ra= combat 7one for the first time on August /(
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GPS And Applications Seminar Report ‘04
7.1.2 GPS 8AMMING
A large %art of modern munitions, the so8called 9smart bombs9
or %recision8guided munitions, use GPS( GPS Fammers are a#ailable, from
Russia, and are about the si7e of a cigarette boB( The U(S( go#ernment
belie#es that such Fammers &ere used occasionally during the U(S( in#asion
of Afghanistan( Some officials belie#e that Fammers could be used to attract
the %recision8guided munitions to&ards noncombatant infrastructureH other
officials belie#e that the Fammers are com%letely ineffecti#e( n either case,
the Fammers are attracti#e targets for anti8radiation missiles
7.2 AIR
-igure .2
GPS offers an ineB%ensi#e and reliable su%%lement to eBisting
na#igation techni=ues for aircraft( !i#il aircraft ty%ically fly from one
ground beacon, or &ay%oint, to another( >ith GPS, an aircraft$s com%uters
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GPS And Applications Seminar Report ‘04
can be %rogrammed to fly a direct route to a destination( The sa#ings in fuel
and time can be significant(
GPS can sim%lify and im%ro#e the method of guiding %lanes to a
safe landing, es%ecially in %oor &eather( >ith ad#anced GPS systems,
air%lanes can be guided to touchdo&n e#en &hen #isibility is %oor( -or the
%ri#ate %ilot, ineB%ensi#e GPS systems %ro#ide %osition information in a
%ractical, sim%le, and useful form(
7.2.1. GPS Na,i*ati%! i! the Air
Pilots on long distance flights &ithout GPS rely on na#igational
beacons located across the country( Using GPS, aircraft can fly the most
direct routes bet&een air%orts(
7.2.2. GPS i! the C%"9pit
-igure ..
Pilots often rely on GPS to na#igate to their destinations( A GPS
recei#er in the coc,%it %ro#ides the %ilot &ith accurate %osition data and
hel%s him or her ,ee% the air%lane on course(
Dept. of ME MESCE Kuttippuram
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GPS And Applications Seminar Report ‘04
7.$. Sea
7.$.1 Nati"a: Chart Err%r
-igure .)
The data collected from satellite na#igation systems %ro#ide
more accurate information for ma%s and nautical and aeronautical charts(
This eBam%le demonstrates ho& charts are u%dated to %re#ent na#igational
misha%s( GPS is a %o&erful tool that can sa#e a shi%$s na#igator hours of
celestial obser#ation and calculation( GPS has im%ro#ed efficient routing of
#essels and enhanced safety at sea by ma,ing it %ossible to re%ort a %recise
%osition to rescuers &hen disaster stri,es(
GPS im%ro#es efficiency on land as &ell( 5eli#ery truc,s can
recei#e GPS signals and instantly transmit their %osition to a central
dis%atcher( Police and fire de%artments can use GPS to dis%atch their
#ehicles efficiently, reducing res%onse time( GPS hel%s motorists find their
&ay by sho&ing their %osition and intended route on dashboard dis%lays(
Railroads are using GPS technology to re%lace older, maintenance8intensi#e
mechanical signals
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GPS And Applications Seminar Report ‘04
7.' LAND
7.'.1. GPS i! 0ehi":e#
4any ty%es of GPS systems can be used on #ehicles, %ro#iding
the dri#er &ith the current %osition and a local ma%(
7.'.2 Mappi!* the Earth
Sur#eyors and ma% ma,ers use GPS for %recision %ositioning(
GPS is often used to ma% the location of such facilities as tele%hone %oles,
se&er lines, and fire hydrants( Sur#eyors use GPS to ma% construction sites
and %ro%erty lines( -orestry, mineral eB%loration, and &ildlife habitat
management all use GPS to %recisely define %ositions of im%ortant assets
and to identify changes(
5uring data collection, GPS %oints can be assigned codes to
identify them as roads, streams, or other obFects( These data can then be
com%ared and analy7ed in com%uter %rograms called Geogra%hic
nformation Systems (GS)(
7.'.$ Sr,e;i!* -ith GPS
Sur#eying that %re#iously re=uired hours or e#en days using
con#entional methods can be done in minutes &ith GPS(
7.'.' Set Y%r -at"h
+ecause GPS includes a #ery accurate time reference, the
system is also &idely used for time,ee%ing( GPS recei#ers can dis%lay time
accurate to &ithin .12 billionths of a second(
Dept. of ME MESCE Kuttippuram
):
GPS And Applications Seminar Report ‘04
7.'.1 Ma!a*i!* the La!&
The use of GPS is &ides%read in field that re=uire geos%atial
information for managing assets o#er large areas( -orestry, mineral
eB%loration, and &ildlife habitat management all use GPS to %recisely define
%ositions of im%ortant assets and to identify changes(
7.'./ GPS a!& A*ri":tre
GPS recei#ers installed in farm e=ui%ment %ro#ide accurate
%osition information( This enables farmers to a%%ly fertili7ers and har#est
cro%s &ith great %recision(
7.'.7 Yie:& Map
-igure .@
4a%s of cro% yield can be made using agricultural GPS systems(
The ma% sho&n here indicates ho& cro% yield #aries across a field( These
ma%s can be created during har#esting, allo&ing farmers to accurately %lan
ho& the fields should be used and fertili7ed for future cro%s(
Dept. of ME MESCE Kuttippuram
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GPS And Applications Seminar Report ‘04
7.'.< Ne= Fr%!tier# i! S"ie!"e
-igure .*
GPS has made scientific field studies throughout the &orld more
accurate and has allo&ed scientists to %erform ne& ty%es of geogra%hic
analyses( Geologists use GPS to measure eB%ansion of #olcanoes and
mo#ement along fault lines( 'cologists can use GPS to ma% differences in a
forest cano%y( +iologists can trac, animals using radio collars that transmit
GPS data( Geogra%hers use GPS to define s%atial relationshi%s bet&een
features of the 'arth$s surface(
7.1 APPLICATIONS IN INDIA
7.1.1 Ar"hite"tre
GPS is used in architectural sitings( >hen used &ith @5
modeling, GPS %ro#ides a more realistic conteBt for architectural design(
Dept. of ME MESCE Kuttippuram
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GPS And Applications Seminar Report ‘04
7.1.2 E)C%((er"e
!onducting research to de#elo% secure transactions using GPS(
The system &ould feature real8time information on users as &ell as
a%%lications to reduce user fears of com%uter 9hac,ing(9
7.1.$ E&"ati%!
GPS is used to trac, transmission and %o&er line distribution
net&or, ins%ections, trac, container mo#ements, and ma% the location of
ground &ater sources and %ollution
7.1.' Ge%*raphi" I!>%r(ati%! S;#te(#
Remote Sensing Satellites the satellite RS8.5 &ill be launched
from Srihari,ota on Se%tember )/, .//3( "ne of the eB%erimental units on
RS8.5 is a *(.18,g Satellite Position System( Using the Global Positioning
System recei#er on the satellite, the SPS &ill determine the %osition of the
satellite in orbit(
7.1.1 De,e:%p(e!t %> GPS re"ei,er#
ndia has begun to manufacture Global Positioning System
recei#ers, in a %roFect funded by the 5e%artment of 'lectronics and the
5efence Research 5e#elo%ment "rgani7ation( These recei#ers are u% to the
highest standards at half the im%orted cost( The ndian8made recei#ers are
being used commercially by boat o&ners and some military #ehicles and
aircraft(
Dept. of ME MESCE Kuttippuram
)/
GPS And Applications Seminar Report ‘04
7.1./ Gr%!& Tra!#p%rtati%!
+uses Run on Time Than,s to GPS in +angalore, ndia A select
number of buses in the south ndian city of +angalore are running on time
than,s to the constellation of Global Positioning System (GPS) na#igation((
Recei#ers built by +angalore$s based +harat 'lectrical Ctd(, &ere mounted
on )22 of the city$s ),@22 buses in a %ilot %roFect about a year ago( The
%rogram is hel%ing ensure that the buses remain on schedule and ma,e all
their designated sto%s( The recei#ers continuously record each bus$
coordinates, &hich are con#erted by soft&are into locations identifiable by
,no&n landmar,s e#ery )22 meters along the bus route( The recei#ers are
able to store @ days of recordings to %roduce a record of the scheduled
%erformance( This system has hel%ed identify missed tri%s and catch
s%eeding dri#ers
3.1.7 I!>ra#tr"tre De,e:%p(e!t
Digh&ay Automation System ? The Digh&ay Automation
System is a %roFect that %lans to lin, the ndian road and communication
infrastructure( The idea for DAS came from the global %ositioning system(
'lectronic ,ios,s &ill be set e#ery 12 ,m on the high&ays and the #ehicles
&ill ha#e an electronic monitoring de#ice( Truc, o%erators &ill be the first
users of DAS(
7.1.< Mi!i!* ? C%!#tr"ti%!
!oal 4ining? The 4inister of State for !oal, 5ili% Ray, &ould
li,e to increase the use of GPS technology to locate ne& mineral resources,
im%ro#e scientific %lanning for the eB%loitation of natural resources, and
Dept. of ME MESCE Kuttippuram
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GPS And Applications Seminar Report ‘04
better management systems( De said that GPS is already being used in many
areas of coal mining(
7.1.@ SUR0EYING ? MAPPING
+eginning in A%ril .//*, one of the largest, dee%est %i%eline
routes &as ma%%ed( This &as %ossible using differential global %ositioning
system to calculate the %osition of the to& fish from the shi%, &hich &as
usually )228m ahead( The %i%eline that &as laid &as )*8in( for 322 miles at
de%ths in the Arabian Sea to @,122 m( GPS has been eBtensi#ely used in
5elhi 8 Utility 4a%%ing ProFect( -or %hotogrammatry &or, GPS !ontrol
Grid Net&or, co#ering an area of .:22 s=(,m has been established &ith
about 122 g%s control %oint at e#ery @81 ,m on ground( The GPS control
grid net&or, %roFect &ill be com%leted by 4ay )222 co#ering entire 5elhi
Vehicle Cocation
>e &ant to de%loy the GPS net&or, in almost the &hole
country so that &e can %ro#ide trac,ing systems not only for #ehicle %osition
but other %arameters of the #ehicle such as remaining fuel, s%eed, ha7ard
&arnings, and %redefined messages( All these things ha#e to be monitored
remotely(

Ci,i" b%&; i!#ta::# GPS i! "%!#er,a!"; tr"9#A T&el#e
5um%er %lacers and .: cor%oration conser#ancy lorries might soon ha#e
Global Positioning System (GPS) instruments in %lace(
A re#ie& of the %erformance of the Global Positioning System
(GPS), on four dum%er %lacer truc,s of the !oimbatore !or%oration, has
been found to be effecti#e in trac,ing #ehicles( !onse=uently, the ci#ic body
Dept. of ME MESCE Kuttippuram
@.
GPS And Applications Seminar Report ‘04
has decided to install it in more #ehicles engaged in conser#ancy o%erations(
Dept. of ME MESCE Kuttippuram
@)
GPS And Applications Seminar Report ‘04
As a test case, the !or%oration had installed the GPS in four of
its .: dum%er %lacers in an effort at finding out &hether the technology
could hel% ensure trans%arency in &aste dis%osal( The $%assi#e #ehicle
trac,ing system$ had recorded the entire tri% of each dum%er %lacer( A
%ri#ate institution that had de#elo%ed the GPS %ro#ided the monitoring
office at the !or%oration a $Tri%4a%%$ soft&are and a geo reference city
ma%, containing the names of all the roadsEstreets and the &aste dum%
locations across the city( A tri% summary &as do&nloaded from the GPS in
one of the truc,s on Tuesday to re#ie& its %erformance and also to chec,
&hether there &ere any route di#ersions( t &as found that the GPS fulfilled
the re=uirements of the !or%oration and hence it had been decided to installs
.) more dum%ers and lorries &ith the GPS
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GPS And Applications Seminar Report ‘04
Chapter 0III
CONCLUSION

The digital re#olution combined &ith the %rogressing
communication theory brought tremendous ad#ancements in information
re#olution( '#en if there are %roblems &ith the %resent GPS system it offers
a credible ser#ice to both high end and lo& end users( There are also a
#ariety of techni=ues a#ailable to correct the %itfalls( As of no& the %resent
research in the field is to reduce the cost, increase the accuracy( t also aims
at reducing the &eight and to clear the line of sight bet&een GPS recei#er
and four satellites(
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GPS And Applications Seminar Report ‘04
REFERENCES
o Global Positioning System Standard Positioning Ser#ice S%ecification,
)nd 'dition, <une ), .//1(
o Doffmann8>ellenhof, +( D( Cichtenegger, and <( !ollins( .//*( GPS?
Theory and Practice( @rd ed( Ne& Ior,? S%ringer8Verlag(
o Ga%lan, 'lliott 5( ed( .//:( Understanding GPS? Princi%les and
A%%lications( +oston? Artech Douse Publishers(
Other Re:ate& -ebPa*e#A
o &&&(aero(orgEhome(html
o &&&(a#&eb(com
o auto(ho&stuff&or,s(comE
o &&&(trimble(com
o &aas(stanford(eduE
o &&&(garmin(comE
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GPS And Applications Seminar Report ‘04
AC.NO-LEDGEMENT
o&e a great deal to the senior faculty of the 5e%artment of
4echanical 'ngineering, 4'S !ollege of 'ngineering, Gutti%uram for the
successful com%letion of this seminar and its re%ort(
am indebted to Mr. 2i:a: .., Cecturer, 5e%artment of 4echanical
'ngineering &ho guided me throughout this seminar( Dis o#erall guidance
and direction has been res%onsible for the successful com%letion of this
seminar(
also eB%ress my than,s to our res%ected Dead of the 5e%artment,
Pr%>.T.N. Sath;a!e#ha! for all the assistance he rendered(
also than, my friends for their constructi#e criticism and their
doubts and =uestions hel%ed me a lot(
Cast but not the least eB%ress my sincere than,s to them &hom
inad#ertently failed to mention(
Dept. of ME MESCE Kuttippuram
@:
GPS And Applications Seminar Report ‘04
A2STRACT
n the beginning of the ./
th
century &e had the industrial
re#olution, in the middle of the )2
th
century &e ha#e the digital re#olution,
and in the da&n of the ).
st
century &e ha#e the communication re#olution(
The maFor inno#ation &hich u%turned the communication re#olution is the
artificial satellite( Generally satellites use the latest technology for
communication, remote sensing, &eather forecasting and the li,e(
Global %ositioning system, usually called GPS are used to
communicate &ith satellites and &ith recei#ers in the different %arts of the
&orld( This seminar aims to thro& light into the technical details,
ad#antages, %itfalls and maFor a%%lication areas of the GPS systems(
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GPS And Applications Seminar Report ‘04
CONTENTS
!ertificate ii
Ac,no&ledgement iii
Abstract i#
!ontents i#
Cist of Tables J -igures #i
1. INTRODUCTION
.(.GPS DST"RI
2. GPS ELEMENTS
)(. SPA!' S'G4'NT
2.1.1 ORBIT
2.1.2 FREQUENCIES
2.1.3 CODES
2.1.4 TIME AND PSEUDO RANGES
)()( !"NTR"C S'G4'NT
)(@ US'R S'G4'NT
)(@(. S.P.S
2.3.2 P.P.S
$. TRILATERATION)THE -OR.ING PRINCIPLE OF
OPERATION
@(. )58TRCAT'RAT"N
@() @58TRCAT'RAT"N
'. MEASURING DISTANCE
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GPS And Applications Seminar Report ‘04
1. SOURCES OF GPS MEASUREMENT ERRORS
1(. !C"!GS
1() "N"SPD'R'
1(@ 4UCTPATD
1(* S'C'!TV' AVACA+CTI
/. TECHNI3UES TO IMPRO0E GPS ACCURACY
:(. 5(G(P(S
:() '(5(G('
:(@>(A(A(S
:(* C(A(A(S
:(1>(A(G('
:(:R(G(P
7. APPLICATIONS
3(. 4CTARI
3() AR
3(@ S'A
3(* CAN5
3(1 APPC!AT"NS N N5A
<. CONCLUSIONS
REFERENCES
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GPS And Applications Seminar Report ‘04
LIST OF TA2LES ? FIGURES
-igure.(
Dept. of ME MESCE Kuttippuram
*2
GPS And Applications Seminar Report ‘04
Dept. of ME MESCE Kuttippuram
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