Hardware Topics of an MF-AM Traffic Information Broadcasting Service

Topics related to an Auto-Radio-Information (ARI) Service are considered. As it is well known, such a service is devoted to an instantaneous message distribution to all traffic-participants: at MF-AM and/or VHF-FM via stereo/mono broadcasting services. When using MF-AM transmission this service is automatically identified by two tones located in the subaudio baseband. One of them is the program identification (PI) signal and the other one is the message-in-progress (ME) signal. In order to be compatible to the usual MF-AM stereo/mono broadcasting requirements, a signalization which uses two tones coherent with the stereo pilot-tone is proposed. In the case of the MF-AM mono transmission, the signalization problem is solved by using internally generated (but not transmitted) mythic tones It only serves as a basic signal in the generation process of higher harmonics which are then used as real signalization tones. The application aspects are examined briefly, giving the experimental results and some possible suggestions for future modifications of the MF-AM stereo/mono broadcasting systems, already in use.