Sanyo Electric Co., Ltd.

Satoshi Nishimura

Kenichi Sato

Youji Sugiura

Takehiko Asano

Tetsuo Shimizu

In a frequency conversion apparatus, the input signal is sampled and stored at one clock frequency, then read out at another clock rate and passed through a filter whose attenuation characteristics are a function of the second clock rate.

Sound signal processing apparatus

A circuit for demodulating either an MFM (modified frequency modulated) or an FM (frequency modulated) self-clocking-information signal is adapted to measure a time period corresponding to a signal reversion period and quantize the measured time period, whereby the quantized output determines a signal reversion period. Pulses of the number corresponding to the quantized output are generated and clock pulses for demodulating the original data are regenerated based on the above described pulses. In the case where the self-clocking-information signal is MFM, the original data is demodulated by reading the data regenerated based on the said pulses of the number corresponding to the quantized output based on the regenerated clock pulses. In the case where the self-clocking-information signal is FM, the original data is demodulated by reading the specified quantized output based on the above described regenerated clock pulses.

Demodulating circuit for self-clocking-information

A frequency region split type noise reducing apparatus, comprising a compressor and an expander; the compressor (or the expander) including a plurality of frequency region splitting filters for splitting the frequency range of the signal into a plurality of frequency regions, a plurality of level sensors for detecting the levels of the signals in the respective frequency regions split by the plurality of filters, a plurality of voltage controlled amlifiers responsive to the level detected outputs of the corresponding level sensors for linearly compressing (or expanding) in terms of a logarithmic scale the dynamic range of the signal, and an adder for adding the outputs as compressed by the voltage controlled amplifiers for providing a composite signal, and the expander (or the compressor) including an amplifier and a switch circuit for connecting the compressor (or expander) to the amplifier to form a negative feedback circuit, whereby the expander (or the compressor) is implemented by a negative feedback amplifier including the amplifier and the negative feedback circuit.

Noise reducing apparatus

An analog sound signal the time axis of which is compressed is sampled responsive to a write clock signal and the sampled output is stored in an analog shift register having a given capacity, whereupon the stored signal is read out from the analog shift register responsive to a read clock signal the frequency of which is smaller than that of the write clock signal. The above described operation is alternately repeated, whereby the output signal read out from the analog shift register is compiled for sound synthesization. The synthesizing junction of the sound signal is controlled by a microcomputer. The microcomputer is adapted to evaluate the similarity of the data concerning the waveform at the trailing end portion of a preceding sound element stored in the random-access memory and the data concerning the waveform at the leading end portion of the succeeding sound element stored in the random-access memory. Evaluation of similarity of the waveforms is effected by evaluating a mean square error or a mutual correlation function of two sets of data. The shift amount of the leading end of the succeeding sound element to be joined to the trailing end portion of the preceding sound element is determined based upon the result of the evaluation, whereby a read circuit is controlled to correct the time axis of the succeeding sound element, thereby to achieve continuity of the waveform at the synthesizing junction of the preceding and succeeding sound elements.

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Kagamigahara, Japan

Satoshi Nishimura