Roadside beacon system
US4823138A · kind A · utility
13Cited by
3References
12Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 15, 1987 |
| Grant date | Apr 18, 1989 |
| Priority date | — |
| Expiry date | Dec 15, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S1/14
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A roadside beacon system having improved reliability in the face of multi-path fading and the presence of large vehicles or the like which shield or scatter the received signal. The roadside antenna is of the split beam type. In the navigation system on the vehicle, the received signal is divided into two parts. The first part is smoothed and its level detected to determine when the vehicle is approaching an antenna. The remaining signal is then employed directly to detect the null in the transmitted beam when the vehicle passes directly in front of the antenna.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.