A transmitter receivable by broadcast band receivers in nearby vehicles, comprising a first signal generator for simultaneously providing a plurality of selectively spaced carriers having frequency spacings corresponding to the individual channels of the band to be covered and selectively providing amplitude modulation when used for the AM broadcast band, and a second signal generator providing an FM modulated signal, which when combined with the signal from the first signal generator, covers various portions of the FM broadcast band to provide complete coverage thereof. A plurality of signals are generated in a portion of a selected band and modulated, according to the selected band mode, with a pre-stored and selectable voice alarm message.