Global Positioning

System (GPS)

Made by class 11 ‘B’ boys.

  The Global Positioning System (GPS) is a U.S.-
owned utility that provides users with
positioning, navigation, and timing (PNT)
services. This system consists of three segments:
WHAT IS GPS..? the space segment, the control segment, and the
user segment. The U.S. Space Force develops,
maintains, and operates the space and control
segments.
  What is GPS…?
 How it came to be..?
 The space segment…
 The control segment…
 The user segment…
 How all segments work together…
 How does navigation work…

INDEX  Augmentation System…

 Why does sometimes GPS show wrong locations…
 Uses of GPS
  The GPS project was started by the U.S. Department of
Defense in 1973. The first prototype spacecraft was
launched in 1978 and the full constellation of 24
satellites became operational in 1993. Originally
limited to use by the United States military, civilian use
was allowed from the 1980s following an executive
order from President Ronald Reagan after the Korean
HOW IT CAME Air Lines Flight 007 incident.[6] Advances in technology
and new demands on the existing system have now led
TO BE. to efforts to modernize the GPS and implement the next
generation of GPS Block IIIA satellites and Next
Generation Operational Control System (OCX). which
was authorized by the U.S. Congress in 2000.
  The GPS space segment consists of a constellation of
satellites transmitting radio signals to users.
 The United States is committed to maintaining the
availability of at least 24 operational GPS satellites,
95% of the time.
THE SPACE  To ensure this commitment, the U.S. Space Force has

SEGMENT been flying 31 operational GPS satellites for well over

a decade.

 GPS satellites fly in medium Earth orbit (MEO) at an

altitude of approximately 20,200 km (12,550 miles).
Each satellite circles the Earth twice a day.
 The satellites in the GPS constellation are arranged
into six equally-spaced orbital planes surrounding
the Earth. Each plane contains four "slots"
occupied by baseline satellites. This 24-slot
arrangement ensures users can view at least four
satellites from virtually any point on the planet.
 The Space Force normally flies more than 24 GPS
satellites to maintain coverage whenever the
baseline satellites are serviced or
decommissioned. The extra satellites may increase
GPS performance but are not considered part of
the core constellation.
  The GPS control segment consists of a global network of
ground facilities that track the GPS satellites, monitor
their transmissions, perform analyses, and send
commands and data to the constellation.
 The current Operational Control Segment (OCS) includes
a master control station, an alternate master control
station, 11 command and control antennas, and 16
THE CONTROL monitoring sites. The locations of these facilities are
SEGMENT. shown in the map above
  The GPS constellation delivers consistently high performance thanks
to the dedicated efforts of its operators — the men and women of the
U.S. Air Force's 2nd Space Operations Squadron (2SOPS) and the Air
Force Reserve's 19th Space Operations Squadron (19SOPS) at
Schriever Space Force Base, Colorado.
 Together, 2SOPS and 19SOPS — nicknamed Team Blackjack — keep
the GPS satellites flying on a 24/7 basis, with continuous availability
Air Force and high accuracy for billions of civilian and military users.

Personnel: Team 
Control Segment Modernization

Blackjack  As part of the GPS modernization program, the Air Force has
continuously upgraded the GPS control segment for many years. The
ground upgrades are necessary to command and control the newer
GPS satellites and to enhance cybersecurity.

 APPLICATIONS OF GPS.(USER SEGMENT)
Like the Internet, GPS is an essential element of the global information infrastructure. The
free, open, and dependable nature of GPS has led to the development of hundreds of
applications affecting every aspect of modern life. GPS technology is now in everything from
cell phones and wristwatches to bulldozers, shipping containers, and ATM's.

GPS boosts productivity across a wide swath of the economy, to include farming,
construction, mining, surveying, package delivery, and logistical supply chain
management. Major communications networks, banking systems, financial markets, and
power grids depend heavily on GPS for precise time synchronization. Some wireless
services cannot operate without it.

GPS saves lives by preventing transportation accidents, aiding search and rescue efforts,
and speeding the delivery of emergency services and disaster relief. GPS is vital to the
Next Generation Air Transportation System (NextGen) that will enhance flight safety
while increasing airspace capacity. GPS also advances scientific aims such as weather
forecasting, earthquake monitoring, and environmental protection.
 Finally, GPS remains critical to U.S. national security, and its applications are
integrated into virtually every facet of U.S. military operations. Nearly all new military
assets -- from vehicles to munitions -- come equipped with GPS.

GPS Services

 GPS satellites provide service to civilian and military users. The civilian service is
freely available to all users on a continuous, worldwide basis. The military service is
available to U.S. and allied armed forces as well as approved Government agencies.
 1 2
How all the segments work
together.

how

3
4
How does navigation work..? This is called trilateration. The first
satellite locates you somewhere on a
sphere (top left of Figure). The second
satellite narrows your location to a
circle created by the intersection of the
two satellite spheres (top right). The
third satellite reduces the choice to two
possible points (bottom left). Finally,
the forth satellite helps calculate a
timing and location correction and
selects one of the remaining two points
as your position (bottom right).

An atomic clock synchronized to GPS is

required in order to compute ranges from
these three signals. However, by taking a
measurement from a fourth satellite, the
receiver avoids the need for an atomic clock.
Thus, the receiver uses four satellites to
compute latitude, longitude, altitude, and
time.
  A GPS augmentation is any system that aids GPS by providing
accuracy, integrity, availability, or any other improvement to
positioning, navigation, and timing that is not inherently part of GPS
itself.
 A wide range of different augmentation systems have been
Augmentation developed by both the public and private sectors.
 To meet specific requirements, the U.S. government has fielded a
Systems number of publicly available GPS augmentation systems.

Some Augmentation aystem that we are familiar with include

Google maps, Google Earth , WAAS, CORS and many more…
 Many things can degrade 1) Satellite signal blockage
GPS positioning accuracy. due to buildings,
Why does GPS Common causes include: bridges, trees, etc.

sometimes show
wrong locations?

2) Indoor or underground 3) Signals reflected off

use buildings or walls
("multipath")
  Far less common causes may
include:
 Radio interference or jamming
 Major solar storms
 Satellite maintenance/maneuvers
creating temporary gaps in coverage
 Improperly designed devices that
do not comply with GPS Interface
Specifications
§ In many cases, a device's GPS hardware is
working fine, but its mapping software is
faulty. For example, users are often misled
by:
§ Incorrectly drawn maps
§ Mislabeled businesses and other points of
interest
§ Missing roads, buildings, communities, etc.
§ Incorrectly estimated street addresses
  The Global Positioning System (GPS) tells you where you
are on Earth.
 There are five main uses of GPS:
 Location — Determining a position.
 Navigation — Getting from one location to another.
 Tracking — Monitoring object or personal movement.
USES OF GPS  Mapping — Creating maps of the world.
 Timing — Making it possible to take precise time
measurements.
 Across the globe the GPS provides critical positioning
capabilities to military, commercial and civil users.