System for bidirectional data transmission between a plurality of stationary units and a vehicle
First Claim
1. A system for bidirectional, electromagnetic transmission of data signals between a plurality of stationary units which have respective effective ranges that at least partially overlap, and a corresponding vehicle unit, wherein the stationary units transmit encoded data signals (ASK) to the vehicle unit (downlink mode), and the vehicle unit transmits encoded data signals (FSK) to the station units by a semi-passive transponder mode, characterized in that at least two stationary units are provided, which operate at predetermined frequency spacings and that in the downlink mode synchronously transmit the same data, and that the reception unit of the vehicle unit is adapted to receive the transmission frequencies of the stationary transmitting units.
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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.
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Citations
10 Claims
- 1. A system for bidirectional, electromagnetic transmission of data signals between a plurality of stationary units which have respective effective ranges that at least partially overlap, and a corresponding vehicle unit, wherein the stationary units transmit encoded data signals (ASK) to the vehicle unit (downlink mode), and the vehicle unit transmits encoded data signals (FSK) to the station units by a semi-passive transponder mode, characterized in that at least two stationary units are provided, which operate at predetermined frequency spacings and that in the downlink mode synchronously transmit the same data, and that the reception unit of the vehicle unit is adapted to receive the transmission frequencies of the stationary transmitting units.
Specification