Radio receiver with two different traffic information decoders

Abstract

An autombile radio capable of receiving VHF entertainment programs from a station in which traffic information signals are modulated in a 57 kHz subcarrier is equipped with two decoders for the 57 kHz subcarrier signals, one decoder for traffic information signals modulated in an analog fashion on the subcarrier and another decoder for digital signals modulated on that subcarrier by double-sideband suppressed-carrier modulation. The first decoder is for a system already in use in which traffic information, at least if urgent, is intended to override the entertainment program, and the receivier has the usual circuits for that override. The second decoder is for a system that is planned but not yet in use in which the received digital signals can call out one or more standard messages or message portions from a read-only memory and either the memory addresses or the memory outputs are storable. They are made audible by speech synthesizer and, because they are stored at least until the next message comes in, can be recalled if the user wishes. The receiver switch for turning on the traffic information feature is a selector switch with positions selecting either type of decoder and, in a modification designed for where both systems are available, the corresponding switching system gives priority to the presently existing system, since the output of the other system will not be lost and can be reproduced when the signals of the existing system have ceased.