| 摘要 |
A waveform encoder has an input (12), a clock generator (30, 34) and respective detectors (14, 18, 26) for detecting maxima, minima and zeros in the waveform. During encoding, values of alternate maxima and minima are combined with associated timing information, and stored as a digital signal in a memory (42, 46). The waveform generator includes a variable wavefunction generator (55, 56, 62, 64, 76, 78, 50, 48, 72, 80, 70, 82) for generating segments of a predetermined wavefunction of period determined by the timing information and of amplitude determined by values of consecutive maxima and minima. The wavefunction can be a cosine wave. The output waveform is generated by joining together consecutive segments. The wavefunction segments are produced in the wavefunction generator by output DACs (70, 72) fed from PROMS (78, 76) containing values of sampled points representing the predetermined wavefunction. Reference DACs (64, 66) are fed alternately with amplitude levels between which the segments extend, and the reference DACs control the output levels of the output DACs. |
