Victor Company of Japan, Limited

Mitsuaki Tanaka

Masatsugu Kitamura

Hiroyuki Takekura

Hidetsugu Suzuki

In a data compression system, a digital signal comprising a series of digital samples and a sampling datum indicating the sampling interval of the digital samples are written into a read-write memory (M2). The digital samples and the associated sampling datum are read out of the memory into first and second digital-to-analog converters (DAC1, DAC2), respectively. The output of the first digital-to-analog converter is applied to a variable frequency low-pass filter (5) to remove the components having frequencies higher than a presettable frequency limit value which is variable as a function of the output of the second digital-to-analog converter so that the cut-off frequency is lower than one-half the sampling frequency to eliminate quantum noise.

Method and system for decoding a digital signal using a variable

A data compression system comprises an analog-to-digital converter for quantizing the analog signal at a first sampling frequency into a series of digital samples and a memory for storing the digital samples. A control circuit generates a sampling datum indicating a variable sampling frequency lower than the first sampling frequency as a function of the instantaneous frequency of the analog signal for selecting digital samples from the memory, reads the selected digital samples out of the memory means in response to the sampling datum, and forms the sampling datum and the selected digital samples into a data set. A series of data sets may be transmitted to a receiving end of the system or stored in a recording medium. The sampling datum is used to indicate the point at which the digital sample is converted to a corresponding analog value.

Method and system for data compression by variable frequency sampling

In a data compression system, a digital signal comprising a series of digital samples and a sampling datum associated with each digital sample is received by a decoder. The sampling datum indicates the sampling interval of the associated digital sample. The decoder includes a microcomputer for storing the digital signal into a memory (M2) and reading each digital sample and the associated sampling datum. The digital sample is divided by the sampling datum to derive a quotient which indicates the slope of the signal to be recovered. The quotient is integrated by an integrator (6b) to provide interpolation between successive sampling points, so that the original signal is approximated by a plurality of line segments.

Method and system for translating digital signal sampled at variable

According to a first aspect of the invention, a diffraction compensation circuit is employed to relatively raise the level of an input electrical audio signal at low frequencies. A speaker is driven in response to the output signals of the diffraction compensation circuit, thereby offsetting a diffraction characteristic inherent in a speaker enclosure. According to a second aspect of the invention, the radiation surface of the vibrating member of a speaker is made flat. The speaker is installed in an enclosure in such a manner that the flat surface of the vibrating member is flush with the exterior surface of the enclosure, thereby reproducing an audio signal with high fidelity.

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Fujisawa, Japan

Mitsuaki Tanaka