The history and technology of the Global Positioning System

¶ … Global Positioning Satellites

The History of Global Positioning Satellites

The First Global Positioning Satellite

Transmission Functions of the Global Positioning Satellites

Reception of Information from Global Positioning Satellites

Advantages of the Global Positioning Satellites System

Introduction to the Global Positioning Satellites

As the name suggests, the global positioning satellite system is based on satellites. It is a navigational system that comprises of a complex arrangement of satellites that orbit round the earth. Twenty-four in all, these satellites are eleven thousand nautical miles far in space. There are six dissimilar orbits wherein the satellites continually keep revolving. It takes these satellites twenty-four hours to complete two orbital revolutions round the Earth. Upon calculation, the revolutionary speed of these satellites is computed to be around 2,600 meters per second (JA-GPS.com).

The radius of every orbit of the global positioning satellites is approximately 25,000 kilometers from the center of the earth, making them 20,000 kilometers above the planet's crust. The orbital route of global positioning satellites places them approximately between North and South latitudes of 60 degrees each (JA-GPS.com).

Life expectancy of each satellite of the global positioning system is around ten years. As a result, periodic substitution is a recurring process whereby new global positioning satellites are constructed and introduced into the respective orbital. All necessary replacements until the year 2006 have been planned and financially provided for in the Global Positioning System (JA-GPS.com).

The Theory of the Global Positioning Satellites

The technology behind the global positioning satellites system takes its origin from Marconi's comprehension of the radio waves and their utilization for transmission purposes. This radio wave technology was employed for social advantage in the course of 1920s. In these years, radio stations were established, which minimally required a receiver to commence operation. A complex model of the same simple technology applies to the functioning of the global positioning satellites system.

After World War II, most developed nations realized the need for keeping up to the minute inside knowledge of each other. As a result, huge amounts of money were spent towards the development and reinforcement of radio transmission technology. More than that, the need for timely communications led to the development of advanced systems for the transmission and reception of radio waves.

The space exploration that began simultaneously with the advancement of satellites and rockets propelled the development, marking an open avenue for the establishment of a global positioning system that was not disturbed by climatic, geographical and evolutionary changes in global conditions, and whose efficiency sustained unaffectedly.

Early satellites and special radio receivers implanted in the applications connected to the satellites were product of these advancements. The global positioning satellites system is a descendant of such innovation. The remarkable technology that enables reception of radio signals from the 20,000 kilometers distant global positioning satellites system by small portable, pocketsize gadgets is the finest depiction of the theory (JA-GPS.com).

The History of Global Positioning Satellites

The First Global Positioning Satellite

The other name for satellites of the global positioning system is NAVSTAR satellites. The first global positioning satellite was launched in February of 1978. The satellite measured about five meters in breadth and weighed roughly around one ton. The energizing solar panels extended on both sides with the transmission power minimally not beyond fifty watts. Later satellites of the global positioning system were constructed on the same parameters (Federal Radio Navigation Plan, 1994).

Transmission Functions of the Global Positioning Satellites

Every global positioning satellite communicates on three frequencies. The known frequency that the global positioning satellites use for civilian services is known as the "L-1" frequency, measuring 1575.42 MHz (JA-GPS.com).

The orbital radius and path of the global positioning satellites ideally locate them at a place wherefrom satellite signals can be received at any time, by any point on the globe (PBS, 1998). At the North and South poles, the global positioning satellites are not directly overhead, but their signals can be received. However, this slightly affects the accuracy of the satellite signals.

The global positioning satellites transmit signals that contain three kinds of information (Federal Radio Navigation Plan, 1994): the almanac data, ephemeris data, and pseudo-random codes.

The almanac data informs the actual and prospective position of each satellite of the global positioning system to the system's receivers at their requested time of the day. Along with the satellite position, this data also reveals the details on orbital revolution of the satellites in the system. This information is available for any particular satellite in the global positioning system, or all the satellites in it (JA-GPS.com).

Ephemeris data contains information on the satellite status; its remaining life expectancy, fitness and performance. The ephemeris data is vitally required for the effective management of the global positioning satellites system and thus, is continually communicated by every satellite. Additionally, the data provides precise current time and date, without which, the receptor application would not be able to calculate the exact date and time of a performance report. Ephemeris data is important for determining locations on the globe (JA-GPS.com).

The pseudo-random code is unique to each satellite. It is used for the identification of received signals. Every satellite transmits information with its pseudo-random code, which helps note the satellite that is collecting, processing and relaying information. Since it determines the transmitting satellite, the code can be understood as the I.D. code of satellites in the system (JA-GPS.com).

In order to understand how each message is communicated with the almanac and ephemeris data and the pseudo-random code, one can take the following simplified version for instance:

This is satellite number "ABC," at position "M," communicating the requested information at time "N."

Advantages of the Global Positioning Satellites System

Global Positioning Satellites System is one of the greatest, unbelievable services that humankind has been able to invent. This system has many advantages over the older navigational systems that were based on land. Of these, the greatest is the fact that the global positioning satellites system and its transmissions are independent of weather conditions, operating at similar efficiency in all weathers. This is because this navigational system is well beyond the earth's crust, atmosphere and the gravitational field; in space.

Even if the receptor of its signals is in a bad weather condition, the ideal orbital path and radius from earth's center keeps the global positioning satellites system disseminating transmission perfectly. Thus, at every moment of need, the system is there to respond to the need, telling exactly where the application is (PBS, 1998).

This way, global positioning satellites play a part in the history in conjunction with the advancement of the maritime chronometer that became the forerunner to the population resettlement upsurge in the nineteenth century. Just as the chronometer made it possible for seamen to mark their marine routes to great precision levels, highly promoting seafaring activities, global positioning satellites affect the lifestyle of the generations to follow. In addition to these, innumerable applications of global positioning satellites exist, realized and unrealized, which have their collective as well as individual benefits accruing to mankind.