ITS ABOUT GIS

1. UNIVERSITY OF MYSORE
DOS IN GEOGRAPHY
PRINCIPLES OF GEOGRAPHIC INFORMATION SYSTEM
TOPIC:DEFINITION,HISTORY,COMPONENTS,TYPES,WORKING
PRINCIPLES AND APPLICATION OF GPS
SUBMITTED TO
DR.MINUTHA
DOS IN GEOGRAPHY
PRESENTED BY
SALIA ALIAS
DOS IN GEOGRAPHY

2. DEFINITION OF GPS
GPS stands for Global Positioning System. It is a satellite-
based navigation system that allows land, sea, and airborne
users to determine their exact location, velocity, and time 24
hours a day, in all weather conditions, anywhere in the
world.
• Also known as Navigation System with Time and Ranging
Global Positioning System (NAVSTAR) GPS.
• Signals made available for civilian use, known as the
Standard Positioning Service (SPS) can be freely accessed
by general public.
• The more accurate Precise Positioning Service (PPS) can
only be used by authorized government agencies.

3. • In 1957, Russia launched Sputnik, the first satellite to successfully orbit the Earth. As Sputnik orbited the planet,
the satellite emitted a radio signal. scientists to use radio signals to track the movement of the satellite from the
ground.
• They later expanded the idea: If a satellite location could be determined from the ground via the frequency shift of its
radio signal, then the location of a receiver on the ground could be determined by its distance from a satellite.
• In 1958, the Advanced Research Projects Agency (ARPA) used this principle to develop Transit, the world's first
global satellite navigation system. The first satellite for Transit launched in 1960 and the concept, developed by
John Hopkins University APL, was capable of providing navigation to military and commercial users, including the
Navy’s missile submarines. The program was transitioned to the Navy in the mid-1960s and by 1968 a constellation
of 36 satellites were fully operational.
• Transit operated for 28 years until 1996, when the Defense Department replaced it with the current Global Positioning
System (GPS).
HISTORY OF GPS

4. • Throughout the rest of the 1960s, the development of GPS was aided by technological advancements such as solid-state
microprocessors, computers, and bandwidth utilization techniques. The development of atomic clocks at the Naval
Research Laboratory’s (NRL) Naval Center for Space Technology led to advances in a satellite-based navigation system
known as Timation (Time Navigation). The first two Timation satellites, launched in 1967 and 1968, were equipped
with crystal oscillator clocks. A third satellite, launched in 1974, became the first equipped with an atomic clock,
which greatly improved accuracy and provided three-dimensional location coverage.
• Development of GPS (1970s): In the 1970s, the development of GPS as we know it today began with the launch of the
first Block I satellite. The new GPS system aimed to provide a more robust and accurate navigation capability by
utilizing a larger constellation of satellites in Medium Earth Orbit (MEO).
• Dual-Use: In the late 1980s, the U.S. government made the decision to allow civilian use of GPS. Prior to that, the
system had been intentionally degraded for non-military users through a process known as Selective Availability (SA).
After the policy change, civilian GPS receivers gained access to the full accuracy of the system.
• Full Operational Capability (FOC) (1995): In 1995, the GPS system reached Full Operational Capability (FOC),
meaning it had a sufficient number of satellites in orbit to provide continuous and reliable worldwide coverage for both
military and civilian users.

5. • GPS Modernization (2000s): In the 2000s, the United States began a comprehensive modernization effort for the GPS
system, known as GPS III. This modernization involved launching new satellites with improved capabilities, such as
increased accuracy, better anti-jamming capabilities, and compatibility with other global navigation satellite systems.
• GPS Applications: Over time, GPS has become an essential technology in various civilian and commercial applications,
including personal navigation devices, smartphones, agriculture, transportation, surveying, mapping, emergency services,
and many more.
• Global Coverage: With the completion of the GPS constellation and the deployment of regional satellite augmentation
systems (like WAAS in the United States), GPS has achieved nearly global coverage with high levels of accuracy.
Today, GPS remains a vital part of global navigation and positioning systems, and it continues to be actively used for both
military and civilian purposes worldwide. Additionally, other countries have developed their own global navigation
satellite systems, such as GLONASS (Russia), Galileo (European Union), and BeiDou (China), NavIC (india)further
enhancing global positioning capabilities

6. • Roger L. Easton of the Naval Research Laboratory, Ivan A. Getting of
The Aerospace Corporation, and Bradford Parkinson of the Applied
Physics Laboratory are credited with inventing it.

8. COMPONENTS OF GPS
GPS (Global Positioning System) consists of several key components that work together to
provide accurate positioning, navigation, and timing information. These components
include:
1.Space Segment: The space segment comprises a constellation of satellites orbiting
Earth. These satellites continuously transmit signals containing information about their
positions and precise timing. The GPS constellation ensures global coverage, allowing
receivers to communicate with multiple satellites for accurate positioning.
2.Control Segment: The control segment consists of a network of ground-based
monitoring stations and control centers. These facilities track the GPS satellites, monitor
their signals, and perform necessary adjustments to maintain their orbits and precise
clocks. The control segment ensures the accuracy and integrity of the GPS signals.
3.User Segment: The user segment consists of GPS receivers, which are devices that
individuals, vehicles, and other systems use to receive signals from the satellites. These
receivers process the signals to calculate their own positions, velocities, and precise
timing. Modern GPS receivers are available in a wide range of forms, from handheld
devices to integrated systems in vehicles and smartphones.

10. There are at least 4 GPS satellites in the line of sight of a receiver on the earth. The transmitter GPS sends
information about the position and time to the receiver GPS at fixed intervals. The signals that are sent to the
receiver devices are radio waves. By finding the difference in time between the signal sent from the GPS
satellite to the time the GPS receives, the distance between the GPS receiver and the satellite can be calculated.
Using the trilateration process, the receiver locates its position as the signals are obtained from at least three
satellites.
For a GPS to calculate a 2-D position, which includes the latitude and longitude, a minimum of 3 satellites are
required. For a 3-D position that provides latitude, longitude, and altitude, a minimum of 4 satellites are
needed.
Trilateration is defined as the process of determining the location based on the intersections of the spheres. The
distance between the satellite and the receiver is calculated by considering a 3-D sphere such that the satellite is
located at the centre of the sphere. Using the same method, the distance for all the 3 GPS satellites from the
receiver is calculated.
Following are the parameters that are calculated after trilateration:
•Time of sunrise and the sunset
•Speed
•Distance between the GPS receiver to the destination
Working Principles of GPS

13. WORKING PRINCIPLES OF GPS
1.Satellite Constellation: GPS consists of a network of satellites orbiting Earth. there are approximately operational GPS
satellites.
2.Triangulation: GPS uses a technique called trilateration (a form of triangulation) to determine the user's location. A
GPS receiver on Earth measures the time it takes for signals from multiple satellites to reach it.
3.Signal Transmission: Each GPS satellite continuously transmits signals that contain information about its position and
the precise time the signal was transmitted. These signals travel at the speed of light.
4.Receiver Calculation: The GPS receiver on the ground receives signals from multiple satellites and calculates its
distance from each satellite based on the time it took for the signals to arrive. The distance is calculated using the speed of
light and the time delay.
5.Intersection of Spheres: The receiver's distance measurements create a series of spheres centered around each satellite.
The receiver's location is determined where these spheres intersect, pinpointing the user's position in three dimensions
(latitude, longitude, and altitude).
6.Clock Synchronization: Precise timing is crucial for accurate GPS calculations. The satellites have highly accurate
atomic clocks, and the GPS receiver corrects for any time differences between the satellite's clock and the receiver's
internal clock.

14. 7.Satellite Configuration: To ensure accurate positioning, the GPS receiver requires signals from a minimum of four
satellites. Three satellites are needed for the triangulation in a two-dimensional space (latitude and longitude), and the
fourth satellite helps correct for inaccuracies introduced by the receiver's clock.
8.Error Correction: Various sources of error can affect GPS accuracy, such as atmospheric interference and signal
reflection. GPS receivers use techniques like Differential GPS (DGPS) and Assisted GPS (A-GPS) to mitigate these errors
and improve accuracy.
9.Navigation and Positioning: Once the GPS receiver calculates its position, it can display the user's coordinates,
altitude, velocity, and other information. This data can be used for navigation, mapping, surveying, timing, and a wide
range of applications.
It's important to note that the principles behind GPS remain constant, but advancements in technology and satellite
systems might have led to enhancements and refinements in how GPS is implemented and used since my last knowledge
update.

16. TYEPS OF GPS
There are several types of GPS (Global Positioning System) and related navigation technologies that have been developed
over time to serve different purposes and applications. Here are some of the main types:
1.Standard Positioning Service (SPS): This is the basic GPS service available to civilian users. It provides accuracy
within about 10-20 meters under good conditions. SPS is widely used for navigation in vehicles, smartphones, outdoor
activities, and basic mapping.
2.Precise Positioning Service (PPS): PPS is the encrypted, more accurate version of GPS intended for use by the U.S.
military and authorized government agencies. It provides higher accuracy and security than the civilian SPS.
3.Differential GPS (DGPS): DGPS involves using a network of ground-based reference stations to improve the accuracy of
GPS signals. These stations measure and correct GPS signal errors caused by factors like atmospheric interference. DGPS
is commonly used in applications requiring higher accuracy, such as land surveying and maritime navigation.
4.Real-Time Kinematic (RTK) GPS: RTK GPS is a technique used to achieve centimeter-level accuracy in real-time
positioning. It involves a base station with a known location that transmits correction data to a mobile rover unit. RTK is used
in applications like land surveying, construction, and precision agriculture.

17. 5.Indoor Positioning Systems (IPS): While not strictly GPS, IPS technologies use various techniques (such as Wi-Fi,
Bluetooth, and inertial sensors) to provide positioning information within indoor environments where GPS signals may
be weak or unavailable.
6.Multi-constellation GNSS: Beyond the U.S. GPS system, other countries have developed their own global navigation
satellite systems (GNSS), such as Russia's GLONASS, Europe's Galileo, and China's BeiDou. Multi-constellation GNSS
receivers can access signals from multiple satellite systems, enhancing accuracy and availability.
7.Dead Reckoning: Dead reckoning combines GPS data with other sensor data (like accelerometers and gyroscopes) to
estimate position when GPS signals are lost, such as in tunnels or urban canyons

18. Application of GPS
Global Positioning System (GPS) has a wide range of applications across various fields due to its ability to provide
accurate and real-time positioning information. Here are some of the key applications of GPS:
1.Navigation: GPS is perhaps most commonly known for its use in personal navigation devices and smartphone apps. It
provides turn-by-turn directions, route optimization, and real-time traffic updates to help users navigate unfamiliar roads
and reach their destinations efficiently.
2.Mapping and Cartography: GPS technology is essential for creating accurate maps and charts. Surveyors,
cartographers, and geographers use GPS to create detailed maps for various purposes, including urban planning, land
management, and environmental monitoring.
3.Agriculture: GPS is extensively used in precision agriculture to optimize farming practices. Tractors, combines, and
other agricultural machinery are equipped with GPS receivers to guide them along precise paths, apply fertilizers and
pesticides, and monitor crop health.
4.Aviation: GPS is a critical component of modern aviation, aiding pilots in navigation, route planning, and landing. It
enables accurate aircraft tracking and improves safety during all phases of flight.
5.Marine Navigation: GPS is widely used in marine navigation to determine vessel position, plan routes, and avoid
collisions. It's crucial for both recreational boating and commercial shipping.
6.Search and Rescue: GPS plays a vital role in search and rescue operations. Emergency responders and organizations
use GPS coordinates to locate people in distress, such as lost hikers, stranded motorists, or disaster survivors.

19. 7.Geocaching: Geocaching is a recreational activity that involves using GPS coordinates to hide and seek containers (caches)
at specific locations around the world. It combines outdoor exploration with technology and navigation skills.
8.Wildlife Tracking and Conservation: GPS-equipped collars or tags are attached to wildlife to track their movements and
behavior. This data helps researchers study migration patterns, habitat use, and population dynamics for conservation efforts.
9.Scientific Research: GPS is used in various scientific studies, including monitoring tectonic plate movement, studying
climate change, tracking ocean currents, and conducting atmospheric research

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