Patents by Inventor Yohtaro Yatsuzuka

Yohtaro Yatsuzuka has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5128625
    Abstract: A phase lock loop for a digital input signal has a phase detector, a loop filter, a digital voltage controlled oscillator (VCO), an initial phase difference calculator, a center frequency difference calculator and an input buffer memory. In an initial training mode prepared in the PLL operation, an optimum initial phase and an optimum center frequency of the VCO to complete a lock-in state is searched for the input signal stored in the buffer memmory. By estimating the initial phase difference and the center frequency difference between the input signal and the VCO output with repetative kick-offs in calculators, optimum values mentioned above are obtained.
    Type: Grant
    Filed: September 12, 1990
    Date of Patent: July 7, 1992
    Assignee: Kokusai Denshin Denwa Co., Ltd.
    Inventors: Yohtaro Yatsuzuka, Takuro Muratani
  • Patent number: 5113448
    Abstract: An input speech signal is encoded by an adaptive quantizer device (16). The adaptive quantizer device quantizes the predicted residual signal produced by removing correlations from the digital input signal by predictors devices (6, 10). A coefficient or weighting factor, called a leakage, at the predictor device (6) is adaptively adjusted by a leakage selector device (47) depending upon a prediction gain. The prediction gain indicates the accuracy of the prediction. The value of leakage is in the range between 0 and 1, depending upon whether the speech signal is voiced sound or unvoiced sound.
    Type: Grant
    Filed: December 15, 1989
    Date of Patent: May 12, 1992
    Assignee: Kokusai Denshin Denwa Co., Ltd.
    Inventors: Takahiro Nomura, Yohtaro Yatsuzuka, Shigeru Iizuka, Hideki Honma
  • Patent number: 4811396
    Abstract: A speech signal coding system comprises a prediction filter coupled with an output of a quantizer for prediction of a signal. A subtractor provides the difference between an input signal and an output of the prediction filter. A quantizer quantizes the residual signal, which is the difference provided by the subtractor. The quantizer is improved by adaptively adjusting step size for quantization. Thus, the coded outputs, according to the present invention, are the parameter information of the prediction filter, quantized output of the residual signal, and step information for quantization. The quantization step is determined according to the fundamental step size which provides the statistical variance, equal to one, to the quantized signal, and/or the power of the residual signal. Because of an efficient encoding with an adaptive control of the quantization step, the bandwidth for transmission of the coded signal in a communication system or transmission rate of coded speech signal is minimized.
    Type: Grant
    Filed: November 28, 1984
    Date of Patent: March 7, 1989
    Assignee: Kokusai Denshin Denwa Co., Ltd.
    Inventor: Yohtaro Yatsuzuka
  • Patent number: 4757517
    Abstract: A system for transmitting a voice signal is disclosed, in which an input voice signal is predivided into low- and high- frequency residual signals. The low-frequency residual signal is transmitted in the form of waveform codes with higher possible fidelity and lower possible quality deterioration through utilization of the Adaptive Predicture Coding (APC) system or Multi Pulse Excited Coding (MPEC) system, while information on the short-time high-frequency spectrum is extracted from the high-frequency residual signal and is transmitted as information for use in the reproduction of the voice signal on the receiving side.
    Type: Grant
    Filed: March 27, 1987
    Date of Patent: July 12, 1988
    Assignee: Kokusai Denshin Denwa Kabushiki Kaisha
    Inventor: Yohtaro Yatsuzuka
  • Patent number: 4470146
    Abstract: A robust ADPCM encoder with a modified leaky quantizer and a pair of parallel predictors is provided. A large leakage is initially inserted into the quantization scale adaptation by utilizing a number of most recent multipliers in a modified leaky Jayant quantizer. Using a dual predictor feedback loop, inside predictor coefficients are updated by the step size having unit variance instead of by the quantized prediction error.
    Type: Grant
    Filed: April 30, 1982
    Date of Patent: September 4, 1984
    Assignee: Communications Satellite Corporation
    Inventors: Yohtaro Yatsuzuka, Henri G. Suyderhoud
  • Patent number: 4369523
    Abstract: In an optical digital communication system having a plurality of optical repeaters inserted in an optical fiber cable, and a pair of terminal stations installed at the extreme ends of the optical fiber cable, the designation of the particular repeater from the terminal station is performed by the remote control signal which has the pulse pattern with the period designated to each repeater. Each repeater may have a plurality of switches for switching lasers for improving the operational reliability of the same by the redundant technique, and the control and/or the designation of the particular switch is also performed by said remote control signal by selecting the particular period and/or the repetition numbers of the period of the pulse pattern.
    Type: Grant
    Filed: June 10, 1980
    Date of Patent: January 18, 1983
    Assignee: Kokusai Denshin Denwa Co., Ltd.
    Inventors: Norio Seki, Yohtaro Yatsuzuka, Haruo Sakaguchi
  • Patent number: 4341438
    Abstract: The operational reliability of a light source in an optical communication system has been increased by an improved redundant arrangement of light sources and the switching arrangement of the same. The present light source arrangement comprises a plurality of light sources each of which provides a different wavelength from one another, an electrical switch for actuating the selected one of the light sources, said electrical switch being arranged to replace the actuated light source when there is something wrong with the light source in operation, and an optical multiplexer the input of which is coupled to the outputs of the light sources, and the output of the optical multiplexer is connected to an optical fiber cable.
    Type: Grant
    Filed: May 28, 1980
    Date of Patent: July 27, 1982
    Assignee: Kokusai Denshin Denwa Co., Ltd.
    Inventors: Norio Seki, Yohtaro Yatsuzuka, Haruo Sakaguchi
  • Patent number: 4303803
    Abstract: A digital speech interpolation system is combined with an adaptive differential PCM (ADPCM), employing a speech detector for detecting speech signals and for discriminating voiced and unvoiced sounds. An adaptive quantization bit assignment to the speech is adopted to cope with any freeze-out condition. And further PCM speech signals with 8 KHz sampling are applied to ADPCM after shifted 250 Hz down and then converted into 6 KHz sampling frequency, thereby attaining a total gain of about 7 without degrading speech quality.
    Type: Grant
    Filed: August 30, 1979
    Date of Patent: December 1, 1981
    Assignee: Kokusai Denshin Denwa Co., Ltd.
    Inventor: Yohtaro Yatsuzuka