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Digital Multifrequency Generator Using Sinusoidal Counters

IP.com Disclosure Number: IPCOM000049723D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Cukier, M: AUTHOR [+3]

Abstract

The figure illustrates a digital multifrequency generator (MFG) for telephone signaling purposes based on the use of a single stable oscilator and a couple of so-called sinusoidal counters, each directly providing the binary coded values of the samples of one of the sinewaves to be generated.

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Digital Multifrequency Generator Using Sinusoidal Counters

The figure illustrates a digital multifrequency generator (MFG) for telephone signaling purposes based on the use of a single stable oscilator and a couple of so-called sinusoidal counters, each directly providing the binary coded values of the samples of one of the sinewaves to be generated.

Referring to the figure, a single stable oscillator feeds two programmable frequency dividers (PFDs), Row PFD and Column PFD, controlled via a decode circuit from the telephone number generating means F REG. The Row PFD is used for the generation of the row group frequency (697, 770, 852 and 941 Hz) and the Column PFD is used for the generation of the column group frequency 1209, 1336 1477 and 1633 Hz). A Row Sinusoidal Counter driven by the Row PFD provides the binary coded values of the samples of the row group frequency, and a Column Sinusoidal Counter provides the binary coded value of the column group frequency.

The output from the Row Sinusoidal Counter is added to that from the Column Sinusoidal Counter, and the resulting binary values are converted into an analog signal by digital to analog converter DAC to yield a conventional MFG output. The Row Sinusoidal Counter is comprised of a combinatorial logic circuit and a set of D-type flip-flops (five in the example shown in the figure). The output from the row PFD is applied in parallel to the clock input (CK) of each of the flip-flops whose outputs feed the log...