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US 3,949,299 AGranted
Signal coding for telephone communication system
AssigneeNorth Electric Company
InventorChing-Long Song
Life of this patent
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AssigneeNorth Electric Company
InventorChing-Long Song
Estimating the term…
A telephone communication system reversibly converts input signals into adaptive delta modulated (hereafter ADM) signals and then into pulse code modulated signals. In one embodiment, an encoder of a telephone communication system receives analog signals, for example voice signals, in a comparator which also receives an analog signal from an integrator for periodically providing ADM signals. The ADM signals are provided to a pattern detector responsive to predetermined patterns of the ADM signals to supply a step size increase or decrease signal to the integrator which then generates the analog signal compared with the input signal for forming the ADM signals. Each signal from the pattern detector is a linear pulse code modulated (hereafter LPCM) signal representing a signal increment corresponding to that represented by the ADM signal. Each LPCM signal increment is then added to the total of each preceding LPCM signal increment to form LPCM signals representing the input analog signal. The LPCM signals are then periodically sampled and each sampled LPCM signal converted into a corresponding compressed pulse code modulated (hereafter CPCM) signal for switching and further transmission. In a receiving path of the embodiment, a converter converts input CPCM signals into LPCM signals. Each LPCM signal together with a locally generated signal representing the preceding LPCM signal is provided to a digital comparator which forms an ADM signal encoded in response to the relative magnitudes of the input and generated LPCM signals. The ADM signals are then provided to further means controlled by patterns of the ADM signals for providing a pattern controlled signal to an integrator which integrates the pattern controlled signal into an analog signal corresponding to the CPCM signal input to the receiving path of the embodiment.
In a telephone communication system having a plurality of transmission lines over which voice signals are transmitted in digital form using pulse code modulation;
An encoder for a pulse code modulation telephone system, said encoder comprising input means over which analog signals are received, adaptive delta modulation means connected to said input means and operative to convert said analog signals to adaptive delta modulation signals, and digital converter means coupled to said adaptive delta modulation means and operative to convert said adaptive delta modulation signals to pulse code modulation signals;
An encoder for a pulse code modulation telephone system, said encoder comprising input means over which signals are received in analog format, adaptive delta modulation means, and a linear pulse code modulation converter;
A decoder for a pulse code modulation telephone system, said decoder comprising digital input means over which digital signals comprising pulse code modulated words are received, receiving digital converter means coupled to said digital input means to convert said digital signals to adaptive-delta-modulated pulse signals, and adaptive-delta-modulation to analog converter means coupled to said receiving digital converter and operative to convert said adaptive-delta-modulated pulse signals to analog output signals;
In an encoder for a pulse code modulation telephone system, said encoder comprising input means over which analog signals are received, a signal processing path including an analog to adaptive delta modulation converter circuit including a comparator circuit having a first and a second input, means connecting the received analog signals to said first input of said comparator circuit, and an adaptive delta modulation step controller connected to the output of said comparator circuit for providing pulse coded step size signals representing the increment between samples of the analog signals including path detection means connected to the output of said comparator circuit, an up/down counter connected to the output of said pattern detection means, and a decoder connected to the output of said up/down counter, digital step accumulator means connected to the output of said decoder in said adaptive delta modulator step controller for converting said adaptive delta modulation signals to linear pulse code coded modulated signals, and means connected to a predetermined point in said signal processing path for providing analog signals representative of the signals at such point in the path to the second input of said comparator circuit.
Dependencies are inferred from the claim text.