Localised communications system for vehicles

摘要

The communications system has a transmitter unit (14) to convey messages to other radio locations (A to E) and a receiver unit (2, 12) to receive messages from other radio locations. The transmission characteristics of the transmitter unit and the receiving characteristics of the receiver unit are designed so that only a limited number of vehicles in the neighbouring area can be contacted by radio. The power of the transmitter and receiver units is limited so that signals are restricted to a limited area. Both the characteristics and the power of the transmitter and receiver units can be adjustable, and may be dynamically matched to the speed of the vehicle.