Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1979-04-09
1981-05-26
Atkinson, Charles E.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358135, G10L 100
Patent
active
042700256
ABSTRACT:
A sampled speech compression and expansion system, for two-dimensional prssing of speech or other type of audio signal, comprises transmit/encode apparatus and receive/decode apparatus.
The transmit/encode apparatus comprises a low-pass filter, adapted to receive an input signal, for passing through low-frequency analog signals. A converter is connected to the low-pass filter for converting the analog signal into a digital signal. A buffer memory, whose input is connected to the converting means, stores the digitized signals.
A correlator, having inputs from the A/D converter and the buffer memory, correlates the digital signal received directly from the converter with a delayed signal from the buffer memory. An "interval-select" circuit, whose input is connected to the output of the correlator, uses the autocorrelation value as a basis for comparison with subsequent peaks in the correlation value which are greater than a specified fraction of the autocorrelation value. The interval-select circuit has an output which is connected to the buffer memory, the value of the fractional peaks and their timing being stored in the buffer memory.
A transform circuit, whose input is connected to the buffer memory, performs an even discrete cosine transform (EDCT) of the stored signal. A first modulator, whose input is connected to the output of the EDCT means, differentially pulse code modulates (DPCM) its input signal. A second modulator, whose input is connected to the output of the interval select circuit, differentially pulse code modulates its input signal. A multiplexer, having an input connected to the output of the first and second modulating means, combines the two differentially pulse code modulated signals. A receiver/decoder has circuits which perform an inverse function to those of the transmitter/coder and are arranged in inverse order, from input to output, to those of the transmitter/coder.
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patent: 3952164 (1976-04-01), David et al.
patent: 3979557 (1976-09-01), Schulman et al.
patent: 4045616 (1977-08-01), Sloane
patent: 4076960 (1978-02-01), Buss et al.
patent: 4142066 (1979-02-01), Ahamed
Alsup James M.
Whitehouse Harper J.
Atkinson Charles E.
Johnston Ervin F.
Kemeny E. S.
Sciascia Richard S.
Stan John
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