Digital tone generator
AssigneeInternational Telephone and Telegraph Corporation
InventorHarry Place
Life of this patent
Estimating the term…
Abstract
A stable generator produces a reference square wave signal having a stable given frequency. Logic circuitry is coupled to the generator to provide a plurality of square wave signals each having a different predetermined frequency, each of the predetermined frequencies having a different predetermined relationship to the given frequency. A switching arrangement is coupled to the logic circuitry to select at least one of the plurality of square wave signals of the logic circuitry. A ring counter, resistor tone mixing circuit and filter are coupled to the logic circuitry to provide as an output signal of the digital tone generator a sine wave tone having a frequency equal to the predetermined frequency divided by a given factor of the selected one of the plurality of square wave signals.
Claims41
A digital tone generator comprising:
- first means to generate a reference square wave signal having a stable given frequency;
- second means coupled to said first means to provide a plurality of square wave signals each having a different predetermined frequency, each of said predetermined frequencies having a different predetermined relationship to said given frequency;
- third means coupled to said second means to select at least one of said plurality of square wave signals;
- and
- fourth means coupled to said second means responsive only to said selected one of said plurality of square wave signals to provide as an output signal of said generator one sine wave tone having a frequency equal to said predetermined frequency divided by a given factor greater than two of said selected one of said plurality of square wave signals.
Dependencies are inferred from the claim text.