Global Navigation Satellite System
Et globalt navigationssatellitsystem, eller på engelsk global navigation satellite system, forkortet GNSS, er en generel betegnelse for et globalt dækkende system af satellitter beregnet til navigation.[1] Det amerikanske GPS, det russiske GLONASS og det europæiske Galileo er konkrete eksempler på globale navigationssatellitsystemer. I satellitterne findes nogle uhyre præcise atomure, der via udsendte radiosignaler fra satellitterne kan bruges af enheder på jorden til at bestemme enhedens præcise position inden for få meters nøjagtighed.
I 2019 var GPS og GLONASS de eneste fuldt udbyggede globale navigationssatellitsystemer.[kilde mangler] Kina er ved at udvide BeiDou-navigationssatellitsystemet, så det dækker hele jorden, og EU er ved at udvikle Galileo.
Eksterne henvisninger
- The International GNSS Service (IGS), hjemmeside (engelsk) Arkiveret 17. december 2009 hos Wayback Machine
Fodnoter
- ^ Møllerhøj, Jakob (2013-04-07). "Positionssatellitterne strammer nettet". Ingeniøren.
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A simulation of the original design of the GPS space segment, with 24 GPS satellites (4 satellites in each of 6 orbits), showing the evolution of the number of visible satellites from a fixed point (45°N) on earth (considering "visibility" as having direct line of sight).
The parameters used to simulate the orbits are: eccentricity (e) 0.05, inclination (i) 55° and a separation between orbits of 60° in the right ascension of the ascending node. Within each orbit, the four satellites are evenly spaced (the instant of pass through perihelion being arbitrary for the first satellite in each orbit). The orbital period of the satellites was taken to be 12 hours. The earth was considered a perfect sphere with a radius of 6400 km.
The time in the animation is running about 2880 times faster than real time (half a minute representing 24 hours), as clearly seen in the rotation of earth. The simulation was created using MATLAB and converted to animated gif format using Adobe ImageReady.