DETERMINATION OF PSEUDO RANGE FROM EARTH ORBIT SATELLITE

摘要

PURPOSE: To determine a pseudo range even without a knowledge about the modulation code sequence being carried on a signal by intercepting the modulated radio frequency signal having a predetermined frequency component transmitted from a satellite at a user station. CONSTITUTION: A user is located at a point 16 on the ground surface. In a global coordinate having an origin at the center 18 of the globe, the user point 16 is represented by → R and the position of a satellite 10 is represented by →ρs. The point 16 exists in an observation horizontal plane 20 intersecting a radial line 22 passing the center 18 perpendicularly. The satellite 10 located oppositely to the globe 12 on the plane 20 at a part of the orbit 14 shown by a solid line can be determined visually by a user at the point 16. User at the point 16 can intercept a radio signal from the satellite so long as the satellite 10 can be seen. Owing to a Doppler frequency shift, frequency fM being measured at the point 16 is maximized when the satellite 10 rises over the plane 20, minimized when goes below the blane 20 and equalized to a receiving frequency fT when the satellite 10 comes to a closest point.