Gps and its application

A Seminar Report on
GPS AND ITS APPLICATION
Submitted in partial fulfilment of award of
BACHELOR OF TECHNOLOGY
degree
Submitted To- Mr .Dheeresh. k. Nayak.
Mr.Rahul Singh.
Mr.Shailendar pal.
Submitted By- Shubham paliwal
Branch- Civil(3rd
year)
University .R.N-121000078
Section- B (class.R.N-44)
Department of civil engineering
GLA University, Mathura UP

1
CONTENTS
 ABSTRACT…………………………………………………………4
 INTRODUCTION……….…………………………………………..5
 History of GPS……………………………………………………….5
 GPS……………………………….…………………………………..6
 HOW IT WORK …………………..…………………………………6
 GPS SIGNAL………………………..………………………………..7
 GPS SEGMENTS……………………..………………………………8
 SERVICES…………………………..……………………………......12
 APPLICATION……………………….……………………………...13
 CONCLUSION……………………….………………………………17
 BIBLIOGRAPHY…………………………………………………….19

2
ACKNOWLEDGEMENT
I extend my sincere gratitude towards Assistant Prof Mr. Dheeresh. K. Nayak , Shalendar Pal
and Rahul Singh.
Head of Department for giving us his invaluable knowledge and wonderful technical
guidance. I express my thanks to all the other faculty members of Department of civil
Engineering , GLA University for their kind cooperation and guidance for preparing and
presenting this seminar. I also thank all my family members and friends for their help and
support.

3
CERTIFICATE
This is to certify that the project report entitled “ GPS and Its application” submitted by
“Shubham paliwal ”in partial fulfillment of the requirements for the award of the Degree
Bachelor of Technology in “civil engineering “ is a bonafide record of the work carried out
under my guidance and supervision at GLA University.
NAME OF SUPERVISOR-
Mr. Dheeresh. K. Nayak.
Mr.Shailendar pal.
Mr.Rahul singh.
Assistant professor
Department of civil engineering
GLA University
Mathura(UP)

4
ABSTRACT
Where am I? Where am I going? Where are you? What is the best way to get there? When
will I get there? GPS technology can answer all these questions .GPS satellite can show you
exact position on the earth any time, in any weather, no matter where you are! GPS
technology has made an impact on navigation and positioning needs with the use of satellites
and ground stations the ability to track aircrafts, cars, cell phones, boats and even individuals
has become a reality. A system of satellites, computers, and receivers that is able to determine
the latitude and longitude of a receiver on Earth by calculating the time difference for signals
from The Global Positioning different satellites to reach the receiver. System (GPS) is a
worldwide radio-navigation system formed from a constellation of 24 satellites and their
ground stations. GPS uses these "Man-made stars" as reference points to calculate positions
accurate to a matter of meters. In fact, with advanced forms of GPS you can make
measurements to better than a centimetre! In a sense it's like giving every square meter on the
planet a unique address. GPS receivers have been miniaturized to just a few integrated
circuits and so are becoming very economical. And that makes the technology accessible to
virtually everyone. Navigation in three dimensions is the primary function of GPS.
Navigation receivers are made for aircraft, ships, ground vehicles, and for hand carrying by
individuals. Precise positioning is possible using GPS receivers at reference locations
providing corrections and relative positioning data for remote receivers. Surveying, geodetic
control, and plate tectonic studies are examples. Time and frequency dissemination, based on
the precise clocks on board the SVs and controlled by the monitor stations, is another use for
GPS. Trying to figure out where you are is probably one of humankind's oldest problems.
Navigation and positioning are crucial to so many activities and yet the process has always
been quite cumbersome and inexact. In the earliest days mankind used the stars to navigate.
Early instruments also sited the stars to determine position. The science of horology began in
part because navigation depended on precise timing the movement of the stars.
Over the years all kinds of technologies have tried to simplify the task but every one has had
some disadvantage. Finally, the U.S. Department of Defence decided that the military had to
have a precise form of worldwide positioning. Fortunately they had the deep pockets it took
to build something really good. The result is the Global Positioning System, a system that's
changed navigation forever.
The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a
constellation of 24 satellites and their ground stations.GPS uses these "man-made stars" as
reference points to calculate positions accurate to a matter of meters. In fact, with advanced
forms of GPS you can make measurements to better than a centimeter!
In a sense it's like giving every square meter on the planet a unique address.
GPS receivers have been miniaturized to just a few integrated circuits and so are becoming
very economical.

5
INTRODUCTION
GPS is primarily a navigational system, so a background on navigation will give insight as to
how extraordinary the Global Positioning System is People first navigated only by means of
landmarks - mountains, trees, or leaving trails of stones. This would only work within a local
area and the environment was subject to change due to environmental factors such as natural
disasters.
For traveling across the ocean a process called dead reckoning, which used a magnetic
compass and required the calculation of how fast the ship was going, was applied. The
measurement tools were crude and inaccurate. It was also a very complicated process .It was
not until the 20th century that ground-based radio navigation systems were introduced. Some
are still in use today.
GPS is a satellite radio navigation system, but the first systems were ground-based. They
work in the same way as does GPS: users (receivers) calculate how far away they are from a
transmitting tower whose location is known. When several towers are used, the location
can be pinpointed. This method of navigation was a great improvement, yet it had its own
difficulties. An example of such a system is LORAN. Each tower had a range of about 500
miles and had accuracy good to about 250 meters. LORAN was not a global system and
could not be used over the ocean. Because ground based systems send signals over the
surface of the earth, only two-dimenstional location can be determined. The altitude cannot
be calculated so this system could not be applied to aviation. The accuracy of such systems
could be affected by geography as well. The frequency of the signal affected accuracy; a
higher frequency would allow for greater accuracy, but the user would need to remain
within the line of sight. The first global navigation system was called OMEGA. It was a
ground-based system but has been terminated as of 1997.
History of GPS -Prior to the development of the GPS system, the first satellite system was
called Transit and was operational beginning in 1964. Transit had no timing devices aboard
the satellites and the time it took a receiver to calculate its position was about 15 minutes.
Yet, much was learned from this system. GPS is a great improvement over the Transit
system. The original use of GPS was as a military positioning, navigation, and weapons
aiming system to replace not only Transit, but other navigation systems as well.
It has higher accuracy and stable atomic clocks on board to achieve precise time transfer.
The first GPS satellite was launched in 1978 and the first products for civilian consumers
appeared in the mid 1980's. It was in 1984 that President Reagan announced that a portion of
the capabilities of GPS would be made available to the civil community. The system is still
being improved and new, better satellites are still being launched to replace older ones.

6
GPS
The Global Positioning System (GPS) is a satellite-based navigation system made up of a
network of 24 satellites placed into orbit by the U.S. Department of Defence. GPS was
originally intended for military applications, but in the 1980s, the government made the
system available for civilian use. GPS works in any weather conditions, anywhere in the
world, 24 hours a day. There are no subscription fees or setup charges to use GPS. GPS is
tained and controlled by the United States Department of Defence. GPS permits land, sea,
and airborne users to determine their three-dimensional position, velocity, and time. It can be
used by anyone with a receiver anywhere on the planet, at any time of day or night, in any
type of weather. This is an amazing capability!
There are two GPS systems: NAVSTAR - United State's system, and GLONASS - the
Russian version. The NAVSTAR system is often referred to as the GPS (at least in the U.S.)
since it was generally available first. Many GPS receivers can use data from both NAVSTAR
and GLONASS; this report focuses on the NAVSTAR system. GPS is a satellite-based
navigation system originally developed for military .purposes. The gps system consists of
three pieces. There are the satellites thattransmit the position information,there are the ground
stations that areused to control the satellites andupdate the information, and finallythere is the
receiver that you purchased. It is the receiver thatcollects data from the satellites
andcomputes its location anywhere inthe world based on information itgets from the
satellites. There is a popular misconception that a gpsreceiver somehow sends informationto
the satellites but this is not true, itonly receives data.
How it works
GPS satellites circle the earth twice a day in a very precise orbit and transmit signal
information to earth. GPS receivers take this information and use triangulation to calculate
the user's exact location. Essentially, the GPS receiver compares the time a signal was
transmitted by a satellite with the time it was received. The time difference tells the GPS
receiver how far away the satellite is. Now, with distance measurements from a few more
satellites, the receiver can determine the user's position and display it on the unit's electronic
map. A GPS receiver must be locked on to the signal of at least three satellites to calculate a
2D position (latitude and longitude) and track movement. With four or more satellites in
view, the receiver can determine the user's 3D position (latitude, longitude and altitude).
Once the user's position has been determined, the GPS unit can calculate other information,
such as speed, bearing, track, trip distance, distance to destination, sunrise and sunset time
and more. GPS works accurately in all weather conditions, day or night, around the clock,
and around the globe. There is no subscription fee for use of GPS signals. GPS signals may
be blocked by dense forest, canyon walls, or skyscrapers, and they don’t penetrate indoor
spaces well, so some locations may not permit accurate GPS navigation. GPS receivers are
generally accurate within 15 meters, and newer models that use Wide Area Augmentation
System (WAAS) signals are accurate within three meters.

7
Signal
GPS satellites transmit two low power radio signals, designated L1 and L2. Civilian GPS
uses the L1 frequency of 1575.42 MHz in the UHF band. The signals travel by line of sight,
meaning they will pass through clouds, glass and plastic but will not go through most solid
objects such as buildings and mountains.
A GPS signal contains three different bits of information - a pseudorandom code, ephemeris
data and almanac data. The pseudorandom code is simply an I.D. code that identifies which
satellite is transmitting information. You can view this number on your Garmin GPS unit's
satellite page, as it identifies which satellites it's receiving.
Ephemeris data, which is constantly transmitted by each satellite, contains important
information about the status of the satellite (healthy or unhealthy), current date and time. This
part of the signal is essential for determining a position.
The almanac data tells the GPS receiver where each GPS satellite should be at any time
throughout the day. Each satellite transmits almanac data showing the orbital information for
that satellite and for every other satellite in the system. These satellites are travelling at
speeds of roughly 7,000 miles an hour.
GPS Segments
GPS uses radio transmissions. The satellites transmit timing information and satellite location
information. PS was designed as a system of radio navigation that utilizes "ranging" -- the
measurement of distances to several satellites -- for determining location on ground, sea, or in
the air. The system basically works by using radio frequencies for the broadcast of satellite
positions and time. With an antenna and receiver a user can access these radio signals and
process the information contained within to determine the "range", or distance, to the
satellites. Such distances represent the radius of an imaginary sphere surrounding each
satellite. With four or more known satellite positions the users' processor can determine a
single intersection of these spheres and thus the positions of the receiver .The system can be
separated into three parts:
1. Space segments
2. Control segments
3. User segment

8
Space segments
The space segment (SS) is composed of the orbiting GPS satellites , or Space Vehicles (SV)
in GPS parlance. The GPS design originally called for 24 SVs, eight each in three
approximately circular orbits, but this was modified to six orbital planes with four satellites
each.
The six orbit planes have approximately 55° inclination (tilt relative to the earth's equator)
and are separated by 60° right ascension of the ascending node (angle along the equator from
a reference point to the orbit's intersection). The orbital period is one-half a sidereal day, i.e.,
11 hours and 58 minutes so that the satellites pass over the same locations or almost the same
locations every day.
The orbits are arranged so that at least six satellites are always within line of sight from
almost everywhere on the earth's surface. The result of this objective is that the four satellites
are not evenly spaced (90 degrees) apart within each orbit. In general terms, the angular
difference between satellites in each orbit is 30, 105, 120, and 105 degrees apart, which sum
to 360 degrees.
Orbiting at an altitude of approximately 20,200 km (12,600 mi); orbital radius of
approximately 26,600 km (16,500 mi),[61] each SV makes two complete orbits each sidereal
day, repeating the same ground track each day. For military operations, the ground track
repeat can be used to ensure good coverage in combat zones .As of December 2012, there are
32 satellites in the GPS constellation.
The additional satellites improve the precision of GPS receiver calculations by providing
redundant measurements. With the increased number of satellites, the constellation was
changed to a non uniform arrangement.
Such an arrangement was shown to improve reliability and availability of the system,
relative to a uniform system, when multiple satellites fail.[64] About nine satellites are visible
from any point on the ground at any one time (see an imation at right), ensuring
consideraredundancy over the minimum four satellites needed for a position.

9
Fig.N-1
Control segment
The control segment is a group of ground stations that monitor and operate the GPS satellites.
There are monitoring stations spaced around the globe and one Master Control Station
located in Colorado Springs, Colorado . Each station sends information to the Control
Station which then updates and corrects the navigational message of the satellites. There are
actually five major monitoring systems, the figure below does not include the Hawaiian
station.
The control segment is composed of..
 a master control station (MCS),
 an alternate master control station
 four dedicated ground antennas, and
 six dedicated monitor stations.
The MCS can also access U.S. Air Force Satellite Control Network (AFSCN) ground
antennas (for additional command and control capability) and NGA (National Geospatial-
Intelligence Agency) monitor stations. The flight paths of the satellites are tracked by

10
dedicated U.S. Air Force monitoring stations in Hawaii, Kwajalein Atoll, Ascension Island,
Diego Garcia, Colorado Springs, Colorado and Cape Canaveral, along with shared NGA
monitor stations operated in England, Argentina, Ecuador, Bahrain, Australia and
Washington DC.[65]
The tracking information is sent to the Air Force Space Command MCS at Schriever Air
Force Base 25 km (16 mi) ESE of Colorado Springs, which is operated by the 2nd Space
Operations Squadron (2 SOPS) of the U.S. Air Force. Then 2 SOPS contacts each GPS
satellite regularly with a navigational update using dedicated or shared (AFSCN) ground
antennas (GPS dedicated ground antennas are located at Kwajalein, Ascension Island, Diego
Garcia, and Cape Canaveral).
These updates synchronize the atomic clocks on board the satellites to within a few
nanoseconds of each other, and adjust the ephemeris of each satellite's internal orbital model.
The updates are created by a Kalman filter that uses inputs from the ground monitoring
stations, space weather information, and various other inputs.
Fig.N-2 Space segments

11
User segment
the user segment is composed of hundreds of thousands of U.S. and allied
military users of the secure GPS Precise Positioning Service, and tens of
millions of civil, commercial and scientific users of the Standard Positioning
Service. In general, GPS receivers are composed of an antenna, tuned to the
frequencies transmitted by the satellites, receiver-processors, and a highly stable
clock (often a crystal oscillator). They may also include a display for providing
location and speed information to the user. A receiver is often described by its
number of channels: this signifies how many satellites it can monitor
simultaneously. Originally limited to four or five, this has progressively
increased over the years so that, as of 2007,receivers typical have between 12
and 20 channels.
Fig.N-3
User segments.

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Services
There are two types of GPS services. Precise Positioning Service (P-code) is more accurate
and reserved for the U.S. military and select government agency users. The other service is
the Standard Positioning Service which is freely available to all users.
The SPS code (C/A code) has errors purposefully encoded into it for U.S. national security
reasons and is used for non-military applications. One source of error is Selective Availability
(SA) and is implenented into the signal in order to keep non U.S. military users from
attaining high accuracy. The errors in the signal are constantly changing. SA affects signals
concerning the satellite's clock and thereby gives false information on how far the satellite is
from the user which makes the receiver give less accurate values. The following table
compares PPS and SPS.
Accuracy in: PPS SPS
horizontal plane 22 meters 100 meters
vertical plane 27.7 meters 156 meters
time transfer 200 nanoseconds 340 nanoseconds
We have learned how to improve the accuracy that can be attained using the freely available
SPS signals. A technique called differential GPS allows for greater accuracy of the civilian
code by removing the error.
This requires two receivers with one stationary knowing its exact location and the other
probably roaming about. Both receivers calculate their positions and the stationary receiver
takes the difference of the calculated position with that of its known position to calculate
what the signal error is.
Since the satellites are so far away, it can be assumed that both receivers are acquiring the
same errors. Once the error is found the receivers can communicate with each other to find
the location of the moving receiver. Differential position accuracies of 1-10 meters are
possible with DGPS.

13
Fig.N-4
APPLICATION OF GPS
The applications of the Global Positioning System fall into five categories: location,
navigation, timing, mapping, and tracking. Each category contains uses for the military,
industry, transportation, recreation and science.
 LOCATION.
 This category is for position determination and is the most obvious use of the Global
Positioning System. GPS is the first system that can give accurate and precise
measurements anytime, anywhere and under any weather conditions. Some examples
of applications within this category are:
 Measuring the movement of volcanoes and glaciers.
 Measuring the growth of mountains.
 Measuring the location of icebergs - this is very valuable to ship captains helping
them to avoid possible disasters.

14
 Storing the location of where you were - most GPS receivers on the market will allow
you to record a certain location. This allows you to find it again with minimal effort
and would prove useful in a hard to navigate place such as a dense forest.
Navigation;
Navigation is the process of getting from one location to another. This was the
what the Global Positioning System was designed for. The GPS system allows us
to navigate on water, air, or land. It allows planes to land in the middle of
mountains and helps medical evacuation helicopters save precious time by taking
the best route.
Timing;
GPS brings precise timing to the us all. Each satellite is equipped with an
extremely precise atomic clock. This is why we can all synchronize our watches
so well and make sure international events are actually happening at the same
time.
Mapping;
This is used for creating maps by recording a series of locations. The best example is
surveying where the DGPS technique is applied but with a twist. Instead of making error
corrections in real time, both the stationary and moving receivers calculate their positions
using the satellite signals. When the roving receiver is through making measurements, it then
takes them back to the ground station which has already calculated the errors for each
moment in time. At this time, the accurate measurements are obtained.
Tracking.
GPS tracking means to trace something or someone with the Global Positioning
System. The below diagram illustrates the basic AVL system. It shows the GPS
signal arriving from satellite to vehicle. The vehicle location is communicated to
the PC (Control Center) via wireless network. But for thousands of years
Homosapiensh as had the opportunity to observe the movement and general
habits of members of his own species as well as of wildlife, particularly by
following their tracks. It was a hard and particular unsafe affair. Hence the
development of satellite tracking by the Argos consortium was a quantum leap in
the human Tracking business. Since 1994 the Global Positioning System has
been available for civilian use at no cost. Nowadays GPS makes it available to
every one to track nearly everything. Objects as well as persons can be tracked if
they are fitted out with a GPS receiver estimating the respective location. The
GPS location data is stored on board of the GPS receiver. Modern GPS tracking
systems are able to send such GPS position data from the object directly to a

15
receiving station.A receiving station can be as tationary receiver of a tracking
service company (in case of car tracking f. ex.) or provider of a mobile phone
company, or just a PC. Nowadays the GPS location data can be also received by
small mobilegad gets like laptops, handsets etc. The AVL tracking system
consists of a GPS receiver inside the vehicle and a communications link between
the vehicle and the control Center as well as pc-based tracking software for
dispatch. The communication system is usually a cellular network similar to the
one used by your cell phone.
Fig.N-5

16
GPS for Private and commercial Use;
the GPS system is free for everyone to use, all that is needed is a GPS receiver, which costs
about $90 and up (March 2005). This has led to widespread private and commercial use. An
example of private use is the popular activity Geocaching where a GPS unit is used to search
for objects hidden in nature by traveling to the GPS coordinates. Commercial use can be land
measurement ,navigation and road T construction.
GPS on Air Planes;
Most airline companies allow private use of ordinary GPS units on their flights, except during
landing and take-off, like all other electronic devices. The unit does not transmit radio signals
like mobile phones, it can only receive. Note, however, that some airline companies might
disallow it for security reasons, such as unwillingness to let ordinary passengers track the
flight route.

17
CONCLUSION
Imagine being an archaeologist on an expedition to the Yucatan Peninsula in Mexico. After
preparing for your trip for months, you are certain that somewhere close by are the ruins of
villages once populated by Mayan Indians. The forest is dense, the sun is hot, and the air is
humid. The only way you can record where you have been, or find your way back to
civilization, is by using the almost magic power of your GPS receiver. Or let's suppose you
are an oceanographer for the International Ice Patrol.
You may be responsible for finding icebergs that form in the cold waters of the North
Atlantic Ocean. Some of these icebergs are 50 miles long. They are a major threat to the
ships that travel those waters, and more than 300 of them form every winter. Using a GPS
receiver, you are able to help ships avoid disaster by zeroing in on the position of the icebergs
and notifying ship captains of their locations, perhaps averting disaster. There will probably
be a time soon when every car on the road can be equipped with a GPS receiver, including a
video screen installed in the dashboard.
The indash monitor will be a full-color display showing your location and a map of the roads
around you. It will probably monitor your car's performance and your car phone as well.
Systems as amazing as this one are already being tested on high ways in the United States.
GPS is rapidly changing the way people are finding their way around the earth. Whether it is
for fun, saving lives, getting there faster or whatever use you can dream of, GPS navigation is
becoming more common every day. GPS will figure in history alongside the development of
the sea-going chronometer.
This device enabled seafarers to plot their course to an accuracy that greatly encouraged
maritime activity, and led to the migration explosion of the nineteenth century. GPS will
affect mankind in the same way. There are myriad applications that will benefit us
individually and collectively.
Glossary and Acronyms
C/A code -The standard (Course/Acquisition) GPS code. A sequence of 1023 pseudo-
random, binary, biphase modulations on the GPS carrier at a chip rate of 1.023 MHz. Also
known as the "civilian code."
Control segment - A world-wide network of GPS monitor and control stations that ensure
the accuracy of satellite positions and their clocks.
Differential positioning - Accurate measurement of the relative positions of two receivers
tracking the same GPS signals.
DGPS - Differential GPS

18
Ephemeris - The predictions of current satellite position that are transmitted to the user in the
data message. A table given for successive days the positions of heavenly bodies.
GLONASS - GLObal NAvigation Satellite System – Russian
GPS - Global Positioning System
Latitude - the location on the Earth measuring how far north or south of the equator one is.
Longitude - the location on the Earth measured east or west
LORAN - LOng RAnge Navigation
Nautical mile - length measurement used in navigation and is 1/60 of 1 degree of the equator.
One nautical mile is 6,080.2 feet whereas one mile is 5,280 feet.
NAVSTAR GPS - the Navigation Satellite Timing and Ranging GPS
P-code - The Precise code. A very long sequence of pseudo random binary biphase
modulations on the GPS carrier at a chip rate of 10.23 MHz which repeats about every 267
days. Each one week segment of this code is unique to one GPS satellite and is reset each
week.
Precise Positioning Service (PPS) - The most accurate dynamic positioning possible with
standard GPS, based on the dual frequency P-code and no SA.
Pseudolite - A ground-based differential GPS receiver which transmits a signal like that of an
actual GPS satellite, and can be used for ranging.
RTK - Real Time Kinematic
Satellite constellation - The arrangement in space of a set of satellites.
Selective Availability (SA) - A policy adopted by the Department of Defence to introduce
some intentional clock noise into the GPS satellite signals thereby degrading their accuracy
for civilian users.
Space segment - The part of the whole GPS system that is in space, i.e. the satellites.
Standard Positioning Service (SPS) - The normal civilian positioning accuracy obtained by
using the single frequency C/A code.
segment - The part of the whole GPS system that includes the receivers of GPS signals.

19
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Gps and its application

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