Vmx, Incorporated

Apple Inc.

Eatamar Drory

Clifford N Baumann

Robert J Machuta

Ron A Perry

A process for determining the presence of either speech or one of a plurality of expected single-frequency signals on a line includes the steps of measuring the total signal energy on the line; measuring the signal energy present in each one of a plurality of selected separate frequency bands and identifying the two frequency bands having the highest signal energies; determining whether the highest signal energy exceeds a first selected threshold value; determining whether the highest signal energy exceeds the second highest signal energy by greater than a second selected threshold value; determining the amount of out-of-band signal energy; and determining whether the highest signal energy exceeds the out-of-band signal energy by greater than a third selected threshold value. A process for determining the presence of two of a plurality of expected a single-frequency signals on a line includes the steps of measuring the total signal energy on the line; measuring the signal energy present in each one of a plurality of selected separate frequency bands and identifying the three frequency bands having the highest signal energies; determining whether the two highest signal energies exceed a first selected threshold value; determining whether the second-highest energy exceeds the third-highest energy by a second selected threshold value; determining the amount of out-of-band signal energy and determining whether the sum of the two highest signal energies exceeds the out-of-band energy by a third selected threshold value; and determining whether the ratio of the two highest signal energy values exceeds a fourth selected threshold value. A method for identifying expected call progression signals on a telephone line, comprises the steps of (1) sensing the presence of energy on the line and determining if the energy comprises speech; (2) identifying the frequency content and duration of the energy; 3) comparing the frequency content of the energy with stored information comprising the frequency content of expected signals and identifying the energy as one of the expected call progression signals if a match is found; (4) sensing the presence of silence on the line if no match is found; (5) identifying the duration of the silence; (6) repeating steps (1) through (5) for a predetermined number of times; and then (7) comparing the frequency content of the energy, the duration of the energy, and the duration of the silence with stored information comprising the frequency content of energy, the duration of energy, and the duration of silence for a plurality of expected call progression signals and identifying the energy as one of the expected call progression signals if a match is found.

Adaptive efficient single/dual tone decoder apparatus and method for

A method for real-time recognition of speech and call-progression tone energy includes the steps of digitizing an analog signal present on a signal line, correlating N neighboring portions of the digitized signal, performing FFT analysis on the digitized signal, identifying the three largest frequency-domain maxima, determining whether the two largest maxima are above a threshold frequency, and determining whether the ratio of the largest to the third largest maxima exceeds a predetermined value. According to the present invention, the steps of the method may be performed in real time using fixed-point hardware by approximating the correlation and FFT functions.

Apparatus and method for identifying speech and call-progression signals

A compression and expansion apparatus and method for compressing and expanding digital audio signals using adaptive differential pulse-coding-modulation for high fidelity music is described. The apparatus comprises a predictor, a first and second adder, a first and second adjuster, a quantizer, an inverse quantizer and a step-size adaptor. An input digital signal and predicted signal are added by the first adder, producing the difference between the two signals. The output of the first adder is coupled to the first adjuster which acts as a multiplier to alter the gain and normalize the signal. The signal is then quantized by the quantizer. The output of the quantizer is sent to both the inverse quantizer and the adaptor. The adaptor acts like an automatic-gain-control to control the gain provided by the first adjuster. After inverse quantization by the inverse quantizer, the signal is sent to the second adjuster to remove the effects of the first adjuster process, i.e. denormalize and remove gain. Then the signal is sent to the second adder to add back in the predicted signal removed by the first adder. Next the signal is outputted and sent to the predictor. The predictor uses the output signal to prepare another predicted signal for a subsequently inputted digital signal. Wherein, an inputted digital audio signal and a corresponding outputted digital audio signal are substantially similar.

Growing community of inventors

Santa Clara, CA, United States of America

Eatamar Drory