Position determination and message transfer system employing satellites and stored terrain map
US4839656A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 16, 1984 |
| Grant date | Jun 13, 1989 |
| Priority date | — |
| Expiry date | Aug 16, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/913
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A radio position determination and message transfer system is implemented using a pair of satellites in geostationary orbit for relaying interrogation and reply signals between a ground station and a user-carried transceiver. The user position is calculated based on the arrival times of reply signals received at the ground station via the two satellites, the known transmission time of the interrogation signal from the ground station, and the user's elevation on the surface of the earth. The elevation is derived from a stored terrain map providing local terrain elevations at a plurality of points on the earth's surface. The stored terrain map allows accurate position fixes to be obtained for surface users regardless of the deviation of the local terrain from the spherical or ellipsoidal model of the earth's surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.