Navigation space systems of the I generation
The first reasonable offer on the use of satellites for navigation was born during the investigation of the possible application of radio-astronomy technologies for aeronavigation headed by prof. V.S. Shebshaevich, in the Leningrad Military Engineering Academy of Mozhaiskii in 1957. Further investigations to increase the accuracy of navigation definitions, global support, daily application and independence from weather conditions, allowed to move to the development work over the first Soviet low-orbit system, later called " Cicada. " In 1967 the first navigation domestic satellite "Cosmos-192" was launched into orbit. Navigation satellites provided continuous radio navigation signal transmission at frequencies of 150 and 400 MHz.
In 1979 navigation system "Cicada" of four navigational satellites placed in circular orbits at 1000 km and an inclination of 83 ° and a uniform distribution of planes of the orbits along the equator was comissioned. It allowed the users to enter the radio contact with one of the satellites and determine the coordinates of the targets of their place in the length of the navigation session to 5-6 minutes every one or two hours. Navigation system "Cicada" used norequest range measurments between the user and navigation satellites.
Along the improving of onboard systems and shipborne navigational equipment, the developers paid serious attention to improve the accuracy of definition and predicting the parameters of the orbit navigation satellites.
Navigation space systems of the II generation
In the future "Cicada" satellites were equipped with the receiving instrumentation of the distress objects detecting. The satellite received these signals and relayed to a special ground station, where the computation of the exact coordinates of the emergency objects (ships, aircraft, etc.) was held.
Cicada satellites provided with the distress objects detection equipment formed Cospas system. Together with the US-French-Canadian system "Sarsat" they form an integrated search and rescue service, which numbers several thousand lives saved.
Successful operation of low-orbit satellite navigation systems by the marine users attracted widespread attention to satellite navigation. There was a need for a universal navigation system that satisfies the requirements of all potential users.
However, low-orbit systems could not comply with the requirements of all these classes of users, due to the principles laid in the foundation of the systems. Prospective navigation satellite system of the second generation should provide the user with the possibility of three spatial coordinates, velocity and precise time determination at any time. The structure of the satellite system was chosen - the height of the orbit navigation satellites was 20000 km and to guarantee the user visibility of at least four satellites, their number should be 18, in order to improve the accuracy their number had increased to 24.
Navigation space systems of the III generation
Flight tests of high altitude satellite navigation system, called GLONASS, were started in October 1982 with the launch of the Kosmos-1413. The GLONASS system was brought into operational testing in 1993. To 1995 the whole orbit group of 24 satellites was formed. The system provides continuous global navigation of all types of users with different levels of quality requirements for navigation support. Reduction in funding for space industry in 1990 led to degradation of the GLONASS constellation. The President and the Russian government approved a number of policy documents, including the federal program "Global Navigation System" to provide the systems safety and progress. It supports the creation of a global navigation field to determine the coordinates of the objects with a high degree of accuracy and reliability, the introduction of satellite navigation technologies into the information outline traffic management, improved security in road transport sector of the country, a significant reduction in operating costs, and denial from traditional ground-based navigation radio equipment in perspective.