Highway alert radio

A roadside-to-vehicle communications system, known as Hy-Com is proposed for bringing voice messages pertinent to driving conditions into moving vehicles. It fills the void left by visual aids which tend to lose their efficacy under conditions of darkness, inclement weather, heavy traffic and when driving at elevated speeds. Safer and more comfortable highway travel is Indicated. Also, the improvement in communications can help to increase the volume of traffic handled by existing facilities. The method proposed to transmit the message is through an amplitude-modulated magnetic induction field having a carrier frequency in the 10- 14 kc range. The use of an induction field makes it possible to control the coverage to include only that Traffic directly concerned. Interference to other services or other Hy-Com transmitters is avoided by the abruptness of the message field and thereby Permits all Hy-Coms to operate on one and the same frequency channel. The operation of Hy-Com is automatic once the ignition is turned on. It can share the audio output circuit and speaker with the standard broadcast radio in the car. The standard broadcast will be muted for the duration of the safety message and returned to normal after passing through the message field. If the radio is not on, the Hy-Com receiver will power the audio output stage so the message can be heard. Portable transmitters using ferrite rod-type antennas can be used for emergency applications. Single wire, loop antennas, buried beneath the shoulder surface, and transmitters kept in tamperproof concrete bunkers are proposed for permanent installations.