Accession Number : AD0700039

Title :   CHARACTERISTICS OF A SATELLITE NAVIGATION SYSTEM OPERATED IN CONJUNCTION WITH A USER INERTIAL SYSTEM.

Descriptive Note : Rept. for 1965-Jul 69,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF SYSTEMS ENGINEERING OPERATIONS

Personal Author(s) : Leonard,B. P. ; Woodford,J. B.

Report Date : 30 JAN 1970

Pagination or Media Count : 14

Abstract : A hybrid satellite/inertial navigation system possessing many unique and desirable features is defined. A set of four satellites placed in 24-hour inclined, elliptical orbits can be made so that three satellites form a stationary, circular ground trace with the fourth satellite moving in a smaller, closed path at the center. Three or four such constellations can provide nearly global coverage. The system works on the following principle: Each satellite contains a clock, a transmitter, and a receiver. A master ground station (with associated calibration stations) periodically checks and updates the satellite clocks and ephemerides. The satellites are constantly transmitting a signal modulated with a time code. The user simultaneously receives all four signals, which contain range, time, and satellite position data. With four such measurements the user can both adjust his clock to that of the satellites and compute a three-dimensional fix. Correspondingly, with range rate data, he can establish a three-dimensional velocity. It is important to note that the satellite system described is not self-contained. However, if the user combines this system with an inertial navigation system, many of the advantages of a totally self-contained system can be achieved. The satellite system would be used to position-update, align, and failure-monitor the inertial system and calibrate the accelerometer. (Author)

Descriptors :   (*INERTIAL NAVIGATION, *NAVIGATION SATELLITES), SYNCHRONOUS SATELLITES, INCLINED ORBIT TRAJECTORIES, RANGE(DISTANCE), TIME, CORRECTIONS, CALIBRATION

Subject Categories : Unmanned Spacecraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE