BRIEF HISTORY OF GPS
GPS ( Global Positioning System) is a global navigation satellite system originally developed by the USA Defense Department. It is based on the first satellite navigational system called, Transit, used by the US Navy in 1960. The original system used just 5 satellites which were able to give their ships a navigational fix, once per hour. GPS relies on accurate clocks in space and this method was used from 1967 onwards with the development of the Timation satellite.
A few years later, in 1970s, the first world wide ground based radio navigation system called Omega, came into use. Those of you who have been boating for some years, may remember using Decca Navigator or Loran to navigate. Well GPS is based partly on that form of ground based systems. The other influence came from the Russian Sputnik in 1957. As the team of US scientists were monitoring Sputnik’s radio transmissions, they discovered a variation in the frequency being transmitted ( because of the Doppler effect). This enabled the team to pinpoint the exact postion of the satellite as it moved along its orbit by measuring the Doppler distortion.
Since then the GPS has moved out from US Navy only use to worldwide civilian applications. This was spurred on when in 1983 the USSR shot down a Korean aeroplane after it strayed into their airspace, by mistake. The then US President Ronald Reagan issued a directive allowing GPS to be available for civilian use.
Nowadays GPS systems uses a constellation of between 24 and 32 satellites to transmit signals to receivers that enable them to work out exact location, time and speed. This present system is called Navstar GPS and is managed by the USAF 50th Space Wing. It is used in map making, land surveys, scientific uses, traffic routes, and for marine navigation.
Garmin GPS marine systems are very popular in Britain with sailors and fishermen alike. Garmin GPS have both handheld receivers and fixed, mounted chartplotter units. Other popular makes are Lowrance, Magellan and Furuno. Remember to browse this website to find GPS systems for sale.