The document discusses the Global Positioning System (GPS). It describes GPS as a satellite-based navigation system developed by the U.S. Department of Defense that provides accurate positioning, navigation, and timing services to users worldwide. GPS uses 24 satellites orbiting the Earth to transmit signals that allow GPS receivers to determine their precise location. The system has three segments - the space segment consisting of satellites, the control segment that monitors and maintains the satellites, and the user segment of anyone using a GPS receiver. GPS enables accurate positioning for applications like navigation, mapping, and surveying.

1. GLOBAL POSITIONINGGLOBAL POSITIONING
SYSTEMSYSTEM
SI/GD SUNIL KUMAR
CENTRAL TRAINING COLLEGE

2. WHAT IS G.P.S
• GPS is a location system based on
satellite orbiting the earth [satellite
sig. tech. ]
• Developed by US dept. of defense
for its application as a military
locating utility
• It is also used in nonmilitary
application such as navigation,
surveying & mapping.

3. • Satellite are high enough to avoid the
problems associated with land based
systems.
• GPS can provide accurate position 24 hrs.
a day , any where in the world.
• When using differential correction tech. it
can provide accuracy within 5 meters or
less.
• Uncorrected posn. determined by GPS
satellite sig. produce accuracy up to 50-
100 mtr. range.

4. • The technology is beneficiary to the
GPS user community in terms of
obtaining accurate data up to
about100 meters for navigation,
meter-level for mapping, and down to
millimeter level for geodetic
positioning.
• The GPS uses satellites and
computers to compute positions
anywhere on earth.
• GPS uses a trigonometric approach
to calculate the positions.

5. • Introduction, History, Background,
&characteristics.
• Short form of NAVSTAR GPS.
• Navigation, system with time& ranging,
global posn. System.
• After the Second World War, it became
apparent to the U.S. Dept. of Defense to
found the solution of accurate, absolute
positioning.
• Several projects and experiments ran
during the next 25 years or so, including
Transit, Timation, Loran, and Decca etc.
,these projects were limited in accuracy or
functionality

6. • At the beginning of the 1970s, a new
project was proposed - GPS. This
concept promised to fulfill all the
requirements of the US government.
• It determine ones position
accurately, at any point on the earths
surface, at any time, in any weather
conditions.
• GPS is a satellite-based system that
uses a constellation of 24 satellites
to give a user an accurate position.

7. • To a hiker or soldier in the desert,
accurate means about 15m. To a ship in
coastal waters, accurate means 5m. To a
land surveyor, accurate means 1cm or less.
• GPS can be used to achieve all of these
accuracies in all of these applications.
• The difference being the type of GPS
receiver used and the technique employed.
• GPS was originally designed for military
use at any time anywhere on the surface
of the earth.
•

8. • Soon after the original proposals
were made, it became clear that
civilians could also use GPS.
• The first two major civilian
applications to emerge were marine
navigation and surveying.
• Nowadays applications range from in
car navigation through truck fleet
management to automation of
construction machinery.

9. WORKING PRINCIPLE OF
GPS
• Worldwide coverage
• 24 hours per day
• Low end user cost
• Military safe
• 10-20 mtr. accurate navigation posn.
• It was designed to take over from existing
navigation systems .
• To be supplied to each man in the field and
installed in all military vehicles.

10. GPS navigation has three major
components
• The Space Segment
• The Control Segment
• The User Segment
THE SPACE SEGMENT
• The Space Segment is designed to consist
of 24 satellites orbiting the earth at
approximately 20200km every 12 hours.
• At this time there are 26 operational
satellites orbiting the earth.

11. • The space segment is so designed
that there will be a minimum of 4
satellites visible above a 15° cut-off
angle at any point of the earth’s
surface at any one time.
• . Four satellites are the minimum
that must be visible for most
applications.
• there are usually at least 5 satellites
visible above 15° for most of the
time and quite often there are 6 or 7
satellites visible .

12. • Each satellite contains four precise
atomic clocks (Rubidium and Cesium
standards) and has microprocessor
on board for limited self-monitoring
and data processing .
• The clocks operate at a fundamental
frequency of 10.23MHz. & used to
generate the signals broadcasted
from the satellite.
• The satellites are equipped with
thrusters which can be used to
maintain or modify their orbits.

13. THE CONTROL SEGMENT
• Control Segment consists of one master
control station.[ Colorado Springs serves
as the master control station ]
• 5 monitor stations [Colorado Springs,
Ascension Island, Diego Garcia, Hawaii, and
Kwajalein Island] and 4 ground antennas
distributed amongst 5 locations roughly on
the Earth’s equator .
• The Control Segment tracks the GPS
satellites, updates their orbiting position
and calibrates and synchronizes their
clocks.

14. THE USER SEGMENT
• The User Segment comprises of anyone
using a GPS receiver to receive the GPS
signal and determine their position and/or
time.
• Typical applications within the user
segment are land navigation for hikers,
vehicle location, surveying, marine
navigation, aerial navigation, machine
control etc.
• The GPS receiver decodes the timing
signals from the 'visible' satellites (four
or more) and, having calculated their
distances, computes its own latitude,
longitude, elevation, and time.

15. • This is a continuous process and the
position is updated on a second-by-second
basis, output to the receiver display device
and, if the receiver display device and, if
the receiver provides data capture
capabilities, stored by the receiver-logging
unit.
• the techniques can be broken down into
three basic classes:
• A] Autonomous Navigation
• a single stand-alone receiver, used by
hikers, ships that are far out at sea and
the military. Position Accuracy is better
than 100m for civilian users and about 20m
for military users.

16. B] Differentially corrected
positioning
• commonly known as DGPS, this gives
an accuracy of between 0.5-5m. Used
for inshore marine navigation, GIS
data acquisition, precision farming
etc.
C] Differential Phase position.
• Gives an accuracy of 0.5-20mm.
Used for many surveying tasks,
machine control etc.

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