Phase accumulation dual tone multiple frequency generator

Details Phase accumulation dual tone multiple frequency generator Phase accumulation dual tone multiple frequency generator

1989-04-04

1991-07-23

Ng, Jin F.

Telephonic communications

Supervisory or control line signaling

Substation originated

379418, 328 14, 328128, 364721, H04M 100

Patent

active

050349775

ABSTRACT:
A method and apparatus for generating dual tone multiple frequency signals employing a low frequency quartz oscillator, wherein a phase accumulation dual tone multiple frequency generator is comprised of a low frequency quartz oscillator. Two phase selectors are connected to produce digital phase signals in response to a signal input. Two phase accumulators, each composed of an adder and a register, are connected to accumulate the phase signals. Two ROM based sine wave tables are addressed by the outputs of the accumulators. An adder adds the outputs of the ROMs, and a D/A converter produces an analog output from the output of the adder.

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IBM Technical Disclosure, vol. 15, No. 11, 4/73, Adams et al.
Wireless Word, vol. 87, No. 1551, 12/81, pp. 40-43, Dawson.
International PCT Publication WO83/00588, 2/83.

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