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Global satellite locates systematic GPS reachs his to carry medium application i
From;    Author:Stand originally
[Summary] : The principle that article system introduced GPS and thirdly big subsystem, stress the application in introducing GPS system to be carried in traffic, the application in including to manage in navigation of civil engineer, car and traffic applies with etc

One, brief introduction of GPS of global location system

GPS of system of global satellite location is an U.S. Army be in at the beginning of 70 time " navigation of meridian instrument satellite locates " develop on the technology and rise have sex of global, all-round (terrestrial, marine, aviation and spaceflight) , the navigation fixed position of round-the-clock sex advantage, time, survey fast system. GPS forms by 3 big subsystem: Supervisory system of dimensional satellite system, ground, user receives a system.

The space defends galaxy interconnected system
Dimensional satellite system is formed by satellite of work of 24 when distributing to go up in 6 orbit plane equably fast track, the dip with flat to equator look of each orbit plane is 55 Ο , orbit plane span 60 Ο . Inside each orbit plane, each satellite rises angle of cut to be apart from difference 90 Ο , the satellite on either orbit is compared in the west the corresponding satellite lead on photograph adjacent orbit 30 Ο . In fact, the satellitic amount of dimensional satellite system should exceed 24, so that change in time the satellite of ageing or attaint, safeguard system works normally. This satellite system can make sure the either place in the earth offers 4 above to be able to inspect a satellite to the person that use.

Every satellite of dimensional system every 12 hours (when star) wind earthly a week along intimate circle orbit, hold handleless cup of high accuracy atom by the star (fundamental frequency F=10.23MHZ) control radio catapult is in " low noise window " (in radio window, the 2 frequency to 8 interval are dimensional telemetering and radio interference are measured a paragraph of lowest of area antenna noise preferential choose frequency paragraph) around emissive L1, L2 two kinds of carrier wave, receive a system to broadcast continuously to global user GPS navigation signal. Place of hour of either of whole world of safeguard of net of group of GPS job satellite, either can is opposite the satellite of 4 above has observation (can amount to 11 at most) , realize navigation of ground of successive, real time and fixed position.

The navigation text that GPS satellite sends to broad user is D of a kind of binary data code that does not clear (T) , the code leads Fd=50HZ. To save the satellitic electric energy, interference rejection sex that enhances GPS signal, confidential gender, realize distant satellitic communication, GPS satellite uses bogus noise code to pile up 2 class modulation to D, pile up D code modulation into bogus noise first namely (P code and C/A code) , pile up afore-mentioned two noise modulation to be on two carrier wave of L1, L2 again, form the GPS radio signal that transmits to the user. Accordingly, GPS signal includes two kinds of carrier (L1, L2) pile up with noise of two kinds of bogus (P code, C/A code) . The frequency of signal of these 4 kinds of GPS all results from 10.23MHZ (the fundamental frequency that the star carries atomic clock) fiducial frequency. Certain proportion exists between fiducial frequency and each signal frequency. Among them, p code is accurate code, the United States the interest for oneself, offer American army, government organization and the civil user that get American government is approved to use only, c/A code is thick code, its locate and time precision all is piled up under P, current, the civil client of the whole world all can be used freely unlimitedly.
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