Abstract: A multi-frequency electronic signal transmitter includes apparatus for transmitting an electronic signal on each of a plurality of transmission frequencies in succession such that the signal is detectable substantially without interruption by a compatible receiver within range of the signal, which is tuned to any one of the transmission frequencies. Direct digital synthesis circuitry is responsive to digital data representing the amplitude of respective discrete portions of a sinusoidal waveform for generating an analog signal corresponding thereto. Frequency control circuitry is provided for controlling the direct digital synthesis circuitry to generate the analog signal on each of the selected frequencies in succession. In one embodiment, the transmission frequencies correspond to selected frequencies in an amplitude modulated (AM) radio broadcast band. In another embodiment, the transmission frequencies correspond to selected frequencies in a frequency modulated (FM) radio broadcast band.