The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 23, 1988
Filed:
May. 27, 1986
Jean-Claude Tarbouriech, Ville-La-Grand, FR;
Motorola, Inc., Schaumburg, IL (US);
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.