Waveform generators

Details Waveform generators Waveform generators

1986-05-27

1988-02-23

Dwyer, James L.

Telephonic communications

Supervisory or control line signaling

Substation originated

379418, 328 14, 328 27, H04M 126

Patent

active

047275707

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.

REFERENCES:
patent: 3787836 (1974-01-01), Hagelbarger
patent: 3941942 (1976-03-01), Nash
patent: 3982460 (1976-09-01), Obayashi et al.
patent: 4132871 (1979-01-01), Lake
patent: 4142184 (1979-02-01), Lake
patent: 4185532 (1980-01-01), Hiyoshi et al.

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