Abstract: A cycle-modulating DTMF generator for generating a DTMF signal; the generator comprises a programmable time-pulse generator, counters or up/down counters, a memory unit for storing data, a digital adder, and a digital-to-analog converter. The circuit of such generator is substantially a digital circuit so as to overcome the problem of signal distortion, which usually exists in an analog circuit.

Abstract: A cost effective waveform-generating apparatus that generates accurate and precise waveforms is disclosed. The present waveform-generating apparatus includes a memory for storing a sequence of sampled amplitudes of a waveform, said sampled amplitudes constituting at least two periods of said waveform; a counting circuit, electrically connected to the memory, responsive to a clock signal for generating counting signals; a controlling circuit, electrically connected to the memory and the counting circuit, responsive to the counting signals for controlling the memory to output the sampled amplitudes recurrently; and a digital to analog converter, electrically connected to the memory, for converting the recurrent sampled amplitudes into an analog output.