Abstract: An emergency call system for vehicles using the public highways is described. The system includes a radio transmitter located in each of one or more vehicles. This vehicle transmitter is provided with an output of predetermined information which is selectively operable by the vehicle operator or the passengers. Spaced at predetermined distances along the highway are a plurality of road receivers each having an input tuned to the output frequency of the vehicle transmitter and a coded-signal generator. The coded-signal generator has an output indicative of the road receiver and of the information output of the vehicle transmitter as it is received by the road receiver. This coded-signal is transmitted to a registering means remote from the receiver which decodes and displays the coded signal. As a result of which assistance and/or rescue can be promptly dispatched to the vehicle as a result of the known location of the road receiver.

Abstract: In an emergency call system for vehicles on public roads, in which the vehicle is provided with a radio transmitter adapted to selectively emit a signal in a plurality of modes, a testing system having a receiver for the emitter signal, and an attenuator for suppressing and blocking spurious and unwanted interfering noise connected to the input of the receiver. The output of the receiver is fed to at least one filter by which the mode of the signal is determined. The output of the filter is connected to the input of a plurality of switching circuits adapted to operate signal lamps corresponding to the transmitted signal mode.