Digital tone generator
AssigneeMotorola, Inc.
InventorsJohn M. Burgan, James H. Carlquist, John R. Oakley
Life of this patent
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Abstract
A digital tone generator (1110) includes a digital signal generator (1138) which generates a digital waveform data sequence which is representative of a tone having a predetermined waveform, and an adaptive duty cycle pulse-width modulator (1132) which is responsive to the digital waveform data sequence for generating an an adaptive duty cycle period characterized by a pulse-width modulated digital tone signal having a variable frequency and duty cycle which is generated by selecting a variable number of clock pulses of a predetermined reference clock (31).
Claims19
A digital tone generator, comprising:
- a digital signal generator for generating a digital waveform data sequence which is representative of a tone having a predetermined waveform;
- and
- an adaptive duty cycle pulse-width modulator which is responsive to the digital waveform data sequence being generated for generating an adaptive duty cycle period characterized by a pulse-width modulated digital tone signal having a variable frequency and duty cycle which is generated by selecting a variable number of clock pulses of a predetermined reference clock.
A digital DTMF tone generator, comprising:
- a first digital signal generator for generating a first digital waveform data sequence which is representative of a high DTMF tone having a predetermined waveform;
- a second digital signal generator for generating a second digital waveform data sequence which is representative of a low DTMF tone having a predetermined waveform;
- a digital adder for adding the first digital waveform data sequence and the second digital waveform data sequence to derive a composite DTMF tone data sequence;
- and
- an adapative duty cycle pulse-width modulator which is responsive to the composite DTMF tone data sequence being generated for generating a pulse-width modulated DTMF tone signal having a variable frequency and duty cycle which is generated by selecting a variable number of clock pulses of a predetermined reference clock frequency.
Dependencies are inferred from the claim text.