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Next: 2.3 Control Segment Up: II. Global Positioning System Previous: 2.1 Introduction

2.2 Space Segment

 21+3 space vehicles

 Orbital height about 20,200 km (12 sidereal hours, repeatibility of the constellation every day four minutes earlier in UT)

 Inclination of i=55 degrees, in six orbital planes (A-F), separated  degrees


 Three types of satellites: Block I (1978-1985, development, extincted), Block II (1989-1996, production, the most part of active now) and Block IIR (1997-...replenishment, the new ones).

 Block II: expected life is 7.5 years, 845 kg, the orbit changes usually last several weeks or months, ability to measure distance between satellites (Block IIR), two cesium and two rubidium frequency standard per satellite (accuracy of to .

Figure_2.01



  Two carrier frequencies in L-band derived from the fundamental frequency , L1: and L2: . C/A, P1 (Y1) codes and navigation data over L1 and P2 (Y2) and also navigation data over L2.



Manuel Hernandez Pajares
Thu Jun 4 14:25:37 GMT 1998