Lanasri Dihia

G •P•SBy:

• Definition + History

• GPS (satellite system + signals)

• (Users segments+ competing) of GPS

• GPS receivers + limits

Plan

Introduction

Global Positioning System 

Definition

GPS is a space-based satellite navigation system made up of a network of 32 satellites placed into orbit by the U.S. Department of Defense.

It provides location and time information in all weather conditions, anywhere in the Earth. The system provides critical capabilities to military, civil and commercial users around the world. It is maintained by the United States government and is freely accessible to anyone with a GPS receiver.

History

• 15/04/2023 • 5

The GPS satellite, GPS IIF-3, was launched

1973 1978 2010200419931989 2011 2012

The GPS satellite, GPS IIF-2, was launched

GPS satellite was launched Qualcomm announced successful tests of 

assisted GPS for mobile phones. GPS was fully functional.

the first modern Block-II satellite was launched.

the first experimental GPS satellite known by Block-I GPS satellite was

launched.

GPS was created and realized by the U.S. Department of Defense (by the engineers: Ivan Getting and Bradford Parkinson)  in 1973 formally known as NAVSTAR GPS, it started with 24 satellites.

The GPS satellite system

• The 32 satellites are orbiting the earth about 26,600km above us. They are travelling at speeds of 7,000 miles /h

• GPS satellites are powered by solar energy.

GPS signals• GPS satellites transmit two low power radio signals,

designated L1 and L2. • Civilian GPS uses the L1 frequency of 1575.42 MHz. • The signals travel by line of sight,

A GPS signal

The almanac

data

Ephemeris data

The pseudorando

m code

an I.D. code that identifies which satellite is transmitting information

transmitted by each satellite, contains important information about

the status of the satellite ,current date and time.

tells the GPS receiver where each GPS satellite should be at any time throughout the day.

How it works?

User segments of GPS

• GPS was originally designed to provide position to the US Army, Navy and Air Force;

• GPS plays a major role in American military combat, guiding missiles and bombs to their destinations in Iraq, Afghanistan and elsewhere.

• It is used to avoid collisions in shipping, with all ocean-going vessels required to report via something known as the Automatic Identification System (AIS).

• It has revolutionized fishing, allowing fishers to return to the exact same spot they'd fished before

Competing of GPS

• The Russian Global Navigation Satellite System (GLONASS) was developed contemporaneously with GPS.

• There are also the planned European Union Galileo positioning system,.

• Chinese Compass navigation system, • Indian Regional Navigational Satellite System.

GPS Receivers

Limits of GPS

• Ideal satellite geometry exists when the satellites are located at wide angles relative to each other. Poor geometry results when the satellites are located in a line or in a tight grouping.

Conclusion

• References: this information was gathered from the web.