Abstract: Fast methods of tone detection and tone generation disclosed are particularly suitable for implementation in a digital signal processor. Chebyshev polynomials are employed to generate periodic waveforms and to detect such waveforms. In an alternative aspect of the invention, trigonometric formulae are employed to generate periodic waveforms which are representable as the sum of sine and cosine functions. Unlike analog techniques, the digital techniques do not entail long delays in the generation or detection of tones because a fast iterative recalculation is employed at each step. Accumulated error is avoided by restarting the procedure once a predetermined value is exceeded. Independent choice of a quality factor and a confidence level is provided by the digital tone detection technique.