Accession Number : ADD013090

Title :   Method for Determining the Magnitude of Earth's Gravity.

Descriptive Note : Patent, Filed 27 Feb 84, patented 5 Nov 85,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Evans,Alan G

Report Date : 05 Nov 1985

Pagination or Media Count : 9

Abstract : An improved method is described that directly and continuously determines the magnitude of the earth's gravity in relation to a user platform at one or more selected points on or above the earth's surface. An improved Global Positioning System (GPS) is used to carry out the method and is made up of plurality of twenty-four (24) continuously orbiting GPS satellites that are arranged into three groups of eight satellites with each group or constellation being disposed in its respective plane of a series of three longitudinal planes. Each plane is arranged in predetermined angular and spatial relation to the earth's equatorial plane and the other planes of the series. Any GPS satellite continuously transmits a pair of encoded RF signals at predetermined L-band frequencies. By virtue of this global arrangement of the 24 satellites, the antenna field of view of a user platform is capable of receiving at any time the encoded signals of at least six satellites. A geodetic receiver on the platform together with a receiver microprocessor, a navigation microprocessor, and a microcomputer progressively and continuously process signals received from the satellites for the ultimate purpose of comparing GPS determined vertical acceleration (that is normal to the earth's modeled ellipsoid) with its platform measured gravimeter acceleration (that is normal to the earth's geoid) so as to determine, with greater accuracy, the gravity at one or more selected points.

Descriptors :   *PATENTS, *GLOBAL POSITIONING SYSTEM, GRAVITATIONAL FIELDS, POSITION FINDING, SATELLITE TRACKING SYSTEMS, NAVIGATION SATELLITES, MICROPROCESSORS, ACCURACY

Subject Categories : Navigation and Guidance
      Spacecraft Trajectories and Reentry

Distribution Statement : APPROVED FOR PUBLIC RELEASE