I. What is GPS?

A. History

B. Development

II. How Does GPS Work?

A. Satellites and Receivers

B. The Three Parts of GPS

III. Applications of GPS

A. Military

B. Civilian


The Global Positioning System

With the proliferation of satellite-based

defense systems and their continuing presence in

the media it makes us more aware of our national

defense. The United States is large, economically

strong and a sometimes tumultuous presence in the

global community. Although we may feel secure

because of our superior technology and defense

capabilities, our size and position in world

affairs can make us a target for some countries. We

can no longer be concerned with just our borders

and now what comes from the skies and the sea is

more of a threat than ever before. The United

States government had to develop a way to counter

these possible attacks and the Global Positioning

System (GPS) was conceived.

The Global Positioning System was initiated in

1973 by the Department of Defense (DOD). It was

developed by the the DOD because at a cost of over

twelve billion dollars the government had the

monetary resources to achieve these idealistic

goals. Since that time it has grown from one

satellite used strictly by the military to

twenty-six satellites that can be used by civilians

also. This satellite system is used to determine

the speed and position of an object anywhere in the

world within one hundred meters to mere millimeters

depending on the size and quality of user



The original purpose of GPS was to maintain a

strategic military advantage over our enemies.

Toward the end of the arms race the targeting of

ballistic missiles became so exact they could land

directly on an enemy missile silo and destroy any

missiles inside of it. The ability to take out your

enemies missiles from great distances had a major

effect on the balance of power. To maintain the

balance of power the United States government had

to develop a way to locate surfacing submarines in

a matter of minutes anywhere in the world. With the

use of satellites in orbit the Global Positioning

System was created.

GPS uses twenty-six satellites and ground

tracking stations around the world to compute

distances using time. This is done by finding the

difference between the time a signal is sent and

the time it is received. The satellites have atomic

clocks so the time is extremely accurate. The

receivers position is determined by using three

satellites, this is called



GPS is made up of three segments: space, control

and user. The space segment includes the satellites

and the rockets that launch them from Cape

Canaveral. The satellites are powered by solar

cells and continuously point their solar panels

toward the sun and their antennae toward earth. The

control segment includes the master control station

in Colorado and monitor stations around the world.

This segment makes sure orbits and clocks operate

within acceptable limits. The user segment includes

the equipment used by the military and civilians

who receive GPS signals. ( Kaplan, Elliott.


The military applications of GPS are used in

fighters, bombers, helicopters, submarines and

soldier?s gear. Wartime defense is now more

accurate and dependable than ever. While still the

most important aspect of this technology, GPS is

not used strictly for navigation anymore. Other

uses include but are not limited to: target

designation, air support, soldier rendezvous and

?smart? weapons. ?Smart? bombs use GPS to receive

location information so they can guide themselves

to a preset target. This technology is a great

asset in battle as it basically casts a net over a

battlefield and can locate tanks, vehicles or even

soldiers who may be in immediate danger.

In the everyday world, GPS has also made life

easier and safer. Hikers and hunters can carry hand

held receivers in case they should get lost in the

wilderness. On-board navigation systems in

automobiles let drivers avoid congested freeways

and find better routes to destinations through

voice-activated user equipment. Drivers can also

make cellular calls using these GPS computers

should something happen to them in transit. Other

aspects of this technology are used in farming.

Maps can be created of the fields during harvest

and used the next season to plant and fertilize

areas that need more attention. This increases crop

production while reducing the use and expense of

fertilizers, pesticides and fuel which also helps

our environment. This process is called ?Precision

Farming?. Another very important use of GPS is the

avoidance of in-flight collisions. Airlines are in

the process of equipping their airplanes with GPS

receivers. This will enable each aircraft to detect

other planes in the vicinity and make sure they

don?t cross paths in the air. This is much more

accurate and reliable system than is currently

available and is sure to make the people flying in

these planes more comfortable and secure.

The Global Positioning