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US 4,058,805 AGranted
Digital multitone generator for telephone dialing
AssigneeComdial Corporation
InventorDon W. Lake
Life of this patent
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AssigneeComdial Corporation
InventorDon W. Lake
Estimating the term…
A digital signal generator that produces multifrequency tones in the voice band range for use in telephone station sets utilizing multitone dialing. Amplitude information describing each of eight voice band frequencies is digitally encoded into a sequence of multi-bit words describing the amplitude at successive data points along the waveform. The eight frequencies so encoded are separated into four upper and four lower frequencies and stored in two solid state read-only memories. Upon command amplitude data words for one upper and one lower frequency are sequentially read out of the memory in time synchronization, added, and their sum applied to a digital delta modulation circuit. The delta modulator determines the change between two successive data word sums and describes the change by an output of either a binary one or a binary zero. The delta modulator output thus comprises a series of binary ones and/or zeros forming an aperiodic digital pulse train which is applied to an output module consisting of an integrating network to synthesize an approximation of a multitone dialing waveform which is compatible with the common carrier telephone network.
A digital signal generator for selectively constructing an analog waveform approximation from digitally encoded amplitude information representing a number of such waveforms comprising:
A digital signal generator for selectively providing a multitone waveform approximation representing the sum of at least two sinusoidal waveforms from digitally encoded amplitude information corresponding to each of said sinusoidal waveforms comprising:
The method of selectively generating a multitone waveform approximation from digitally encoded amplitude information representing a number of single-tone waveforms comprising the steps of:
A digital signal generator for selectively constructing an analog waveform approximation from digitally encoded amplitude information representing a number of such waveforms comprising:
A digital signal generator for selectively constructing an analog waveform approximation from digitally encoded amplitude information representing a number of such waveforms comprising:
The method of selectively generating a multitone waveform approximation from digitally encoded amplitude information representing a number of single-tone waveforms comprising the steps of:
The method of selectively generating a multitone waveform approximation from digitally encoded amplitude information representing a number of single-tone waveforms comprising the steps of:
Dependencies are inferred from the claim text.