Yuichi Kojima 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).
Abstract: In transmitting a residual signal determined by the difference between an input signal and a predictive signal, a comparative signal based on the input signal is applied to a plurality of predictors having different respective predictive functions or coefficients, the resulting predictive output signals from the predictors, respectively, are compared with the comparative signal to provide respective difference signals, and the predictor corresponding to the smallest of the difference signals with a predetermined time delay, for example, the next preceding sampling of the input signal, is employed as the source of the predictive signal to be subtracted from the input signal for determining the transmitted residual signal.
Abstract: A waveform shaping circuit for use with a digital signal transmission apparatus includes an N stage shift register having a digital data input terminal and first and second sets of output terminals, a pair of read only memories each having a plurality of address control terminals controlled by the output signal from the first and second sets of output terminals of the shift register and an output signal, an adder supplied with the output signals from the pair of read only memories so as to produce a digital output signal to be D/A (digital-to-analog)-converted.
Abstract: Apparatus for decoding BCH code can correct double errors using a modification of the Chien search method. This decoding apparatus comprises circuits to form syndromes S1 and S3; a circuit to form S1.sup.2 ; a circuit to form S1.sup.3 ; a circuit to form (S1.sup.3 +S3); and Chien search circuit, in which the error-location polynomial .sigma.(x)=(S1x.sup.2 +S1.sup.2 x+S1.sup.3 +S3) is solved, thereby correcting errors of two or less. With this apparatus, there is no need to perform a dividing process, and a high decoding processing speed can be realized without using any PLA or ROM.
Abstract: A method of recording a digital data signal, such as an audio PCM signal, onto a recording medium in the longitudinal direction thereof, together with an apparatus which is suitable for this recording method. Even-numbered words and odd-numbered words in a digital data signal are recorded on a first track group and a second track group, respectively, which are separated from each other in the widthwise direction of a recording medium, to prevent a series of words becoming error words because of, for example, a flaw in the recording medium in the longitudinal direction thereof. The data format is changed at the input and output of a recording encoder to enable an error correction code and a recording circuit to be used in common for digital tape recorders which have different numbers of tracks, e.g., n tracks and 2n tracks.
February 15, 1985
Date of Patent:
September 29, 1987
Eiichi Osawa, Masato Tanaka, Mamoru Yoshizawa, Jun Nakai, Yuichi Kojima
Abstract: A waveform shaping apparatus includes a shift register having a clock input terminal, data input terminals supplied with respective bits of a digital input signal and a plurality of data output terminals, and a plurality of coefficient multipliers connected to the respective data output terminals. A 2's-complement binary code offset within a predetermined range is used for representing the coefficient of each of the multipliers and such coefficient is controlled by manipulation of ON/OFF switches.
Abstract: A converted digital signal is provided in an NRZI (non-return to zero, inverted) code with a zero DC component and with a maximum predetermined number of bits between level transitions in the signal. The base digital signal is divided into m-bit base words, each of which is then converted into an n bit converted code word to form a converted digital signal suitable for recording. The n-bit converted code word is selected from a plurality of primary combinations or code words having a DC component substantially equal to zero when NRZI-coded and a plurality of secondary combinations or code words having a DC component with an absolute value of two when NRZI-coded. A variance of the DSV (digital sum variation) of each primary combination when NRZI-coded and a polarity of the DC component of each secondary combination when NRZI-coded are altered in response to the DSV at the exit of the preceding converted digital signal.
Abstract: A method for converting a digital data into an NRZI-coded digital signal is disclosed which is carried out by the steps of first detecting if the value of every even numbered bit of the digital data is digital zero, second detecting if two bits of the detected even numbered bits having digital zero value and a preceding odd numbered bit have a DC component, producing a detecting signal according to the result of the second detecting; and converting the digital data into the NRZI-coded digital signal by using the detecting signal.
Abstract: In the recording/reproducing of digital audio signals, errors are detected and corrected by using two parity words, one arranged at the center of the block formed of data words and the arranged at one end of the block. The probability that uncorrectable error will be present in the center of the block is relatively high, so placing the parity word there prevents loss of the more valuable data. Maximum correctable burst errors are determined by the length of the block, so placing the other parity word on the end of the block lengthens it and improves burst error correction. The parity words are arranged as indicated before adding a cyclic redundancy check (CRC) code to the data signal and then modulation coding the signal before recording. During playback, the reproduced signal is demodulated and the CRC code used to detect errors for which error pointers are generated.