Ilc Data Device Corporation

Other

Leonard F Shepard

Abram N Spanel

Apparatus for imparting a delay to an input signal utilizing counter means comprised of a plurality of binary coded decimal counter stages connected in cascade. The high frequency input signal applied to the counter undergoes a divide-by 10.sup.N operation wherein N equals the number of binary coded decimal stages. Preferably, the least significant stage is adapted to be selectively and periodically preset to a binary coded decimal value different from its normal reset state to either increase or reduce the number of pulses required to cause the counter stage to read a terminal count to selectively either advance or retard the phase of the reduced frequency output signal developed at the output of the counter relative to the phase of the input signal applied to the counter in accordance with a preprogrammed value set into said counter stage. The number of advance or retard phase offsets may be adjusted over a wide range through the employment of a rate multiplier which sets the aforementioned presettable decade stage a predetermined number of times over a given time interval. The rate at which the said presettable decade stage is set is controlled by an adjustable rate generator which drives the rate multiplier. The number of times which the digital time incrementer is preset over the aforesaid interval is controlled by the setting of the adjustable rate multiplier. Input means are provided for substituting one high frequency input source for another without imposing any additional delay in the signal undergoing a phase adjustment due to the substitution. The digital time incrementer is advantageously incorporated into a microphase stepper capable of providing extremely small precision changes in phase as between an input and an output frequency wherein the output frequency is either equal to or a multiple or submultiple of the input frequency.

Microphase stepper employing improved digital timing incrementer

A telephone adapter for hands-free telephony, adapted for use with a telephone handset having structure including an earpiece, comprising: a transmit signal path comprising, in series, a microphone, amplification means, disabling means and a transducer; a receive signal path having means for amplifying sound energy from said earpiece, said receive path comprising, in series, a coupler, amplification means, disabling means and speaker means; bias means for maintaining said transmit path in an active state when no signals are present; and, means for interrupting said circuit paths in a complementary manner.

Electroacoustical telephone adapter

Method and apparatus for comparing and/or adjusting the frequency output of a frequency source, which method and apparatus is greatly simplified, and permits adjustment within a relatively short time interval and at a precision whose known difference is less than five parts in the 10.sup.12. The rubidium-controlled oscillator employed by the major networks to produce the 3.58 MHz subcarrier signal is utilized as a standard. Offsets made available at regular intervals by the National Bureau of Standards are utilized to indicate the frequency differences between the network standards and the United States Frequency Standard (USFS). The method employs two phase locked loops each having divide by N dividers to electronically perform the mathematical operations represented by the formula ##EQU1## WHEREBY THE DIVISION RATIOS FOR SATISFYING THE VALUES OF THE APPROPRIATE X, X+1, AND X-1 TERMS OF THE EQUATION ARE APPROPRIATELY ADJUSTED TO OBTAIN AN OFFSET WHICH APPROXIMATES THE PUBLISHED OFFSET WITH THE KNOWN DIFFERENCE OF LESS THAN FIVE PARTS IN 10.sup.12. The technique may be employed to adjust a local generator by offsetting its value so as to bring it into phase synchronism with a network standard or, alternatively, the network standard may be adjusted by the offset to the United States frequency standard and then compared with the local oscillator, thus removing almost all of the offset value to thereby bring the frequency of the calibrated oscillator to a value extremely close to the standard where the difference is smaller than that obtainable in any conventional method. Alternatively, the method and apparatus of the present invention permits the use of the oscillator in a standard color television receiver as a high precision frequency source for use in scientific, laboratory, industrial and other applications. Also, primary (i.e. cesium) standards may be offset by use of the electronic offset described herein arranged in multiple unit cascaded fashion.

Growing community of inventors

Dover, DE, United States of America

Leonard F Shepard