Method of and apparatus for obtaining vehicle heading information
US5119101A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 20, 1991 |
| Grant date | Jun 2, 1992 |
| Priority date | — |
| Expiry date | May 20, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/60
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
When fewer than three of the satellites of a satellite global positioning system (GPS) such as NAVSTAR are visible to a user (15), the user cannot obtain independent positional information from the system. Since a satellite (11) in such a system is moving with respect to a user (15), its signals are received with a Doppler offset from their normal centre frequency and the frequency offset due to the satellite motion alone is calculable for a user at an approximate location from a given satellite. An additional Doppler frequency offset will result from any movement of the user. The magnitude of the additional frequency shift, in conjunction with the known speed (m) of the user, can be used to calculate the angle between the satellite motion (V.sub.1) and the user's motion and since the direction of the former is known, the user's heading from local North (N) can be calculated in instances where only one or two GPS satellites (11,12) are visible to a user.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.