System for bidirectional data transmission between a plurality of stationary units and a vehicle
US5444742A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 28, 1993 |
| Grant date | Aug 22, 1995 |
| Priority date | — |
| Expiry date | Apr 28, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L5/143
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system is proposed for bidirectional electromagnetic transmission of data signals between at least two stationary units and one vehicle unit. The stationary units in the downlink mode synchronously transmit the data signals to the vehicle unit and have different carrier frequencies. In the uplink mode, the data signals are transmitted from the vehicle unit to the stationary units by the semipassive transponder principle. In the process, the data signals of the vehicle unit are frequency-modulated to the various carrier frequencies of the stationary units. This arrangement improves the reliability of bidirectional data transmission. A preferred application is data exchange for traffic control systems between stationary beacon units and moving vehicles.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.