Waveform generators
First Claim
1. A waveform generator for synthesizing a waveform by stepwise approximation, comprising programmable means for providing a signal representing the duration of each of a series of steps forming the waveform, and an up/down counter coupled to said programmable means so as to provide an output voltage whose amplitude is incremented by a single predetermined value at the end of the duration of each step in response to the said signal and whose output thus represents a waveform in stepwise approximation in which the amplitude of each step is constant but where the durations of the steps are varied.
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Accused Products
Abstract
A stepwise approximation of a sinewave is generated by inputting different values representing different points on the waveform from a ROM (6) to a step duration counter (5). At the end of each step, a step counter (7) is incremented causing the ROM to input the next value. An up/down counter (3) is also incremented at the end of each step and caused to count in the opposite direction after a preset number of steps. The counter (3) produces an output representing the sinewave where the amplitude of all of the steps are equal but where their duration varies to produce the sinewave shape and this output is then passed to a D/A converter (9). An oscillator (1) is used to provide clock pulses to the step duration counter (5) and also to the up/down counter (3). Two such sinewave generators can be used in a dualtone multifrequency dialling circuit. The amplitude of one of the sinewaves can easily be varied by adjusting the step count so as to pre-emphasize one of the sinewaves and the two sinewaves are digitally mixed by the up/down counter.
28 Citations
27 Claims
- 1. A waveform generator for synthesizing a waveform by stepwise approximation, comprising programmable means for providing a signal representing the duration of each of a series of steps forming the waveform, and an up/down counter coupled to said programmable means so as to provide an output voltage whose amplitude is incremented by a single predetermined value at the end of the duration of each step in response to the said signal and whose output thus represents a waveform in stepwise approximation in which the amplitude of each step is constant but where the durations of the steps are varied.
Specification