Oki Electric Industry Co., Ltd.

Waseda University

Oki Electronics Co., Ltd.

Takuro Sato

Atsushi Fukasawa

Manabu Kawabe

Toshio Kato

Hiromi Ando

Kiyoki Sekine

Akiyoshi Kawahashi

Shinichi Sato

Yukio Suzuki

Kenichiro Hosoda

Haruhiko Akiyama

Yumi Takizawa

Yoshio Masuda

Jun Ashiwa

Tatumasa Yoshida

Tetsuya Kawanishi

Hiroki Sugimoto

Yoshihito Shimazaki

Haruhiro Shiino

Ryoichi Miyamoto

Kenji Horiguchi

Tatsumasa Yoshida

Yasuo Shoji

Seiji Nishi

Kiyohito Tokuda

Kazuhiko Tamesue

The first conductor plate has a groove portion that has a rectangular cross section and is formed in parallel with a first main surface such that the longitudinal direction becomes a first direction, and a first vertical tube portion formed in a direction away from the second conductor plate in a second direction orthogonal to the first direction and the first main surface, with a branch position in the groove as a starting point. The second conductor plate includes a reflection portion that is inserted into the groove portion in a manner protruding from a second main surface, which is a flat surface of the second conductor plate in contact with the first main surface, and has a reflection surface that reflects the radio wave, propagated along the groove portion, toward the first vertical tube portion.

Waveguide, method of manufacturing waveguide and antenna

A transmission device is disclosed in which user data are cross converted, at their base band, by the orthogonal transformers 31.about.34. Signaling data are collected at every integer which does not exceed the ratio of the user data to the signaling data and time division-like multiplexed by the multiplexer 20. The multiplexed data are crossly converted, at its base band, by the orthogonal transformer 35. The base band data cross converted by the orthogonal transformers 31.about.35 are added by the adder 40 and carrier modulated so as to be radio transmitted from the antenna 60.

CDMA communications system using multiplexed signaling data lines

To initiate communication, a first station generates a synchronization signal and sends the synchronization signal to a second station. When the second station detects the synchronization signal, the second station acquires synchronization and sends a synchronization-acquisition message back to the first station. The first station now reduces the power of the synchronization signal, while continuing to send the synchronization signal, and also begins sending a modulated data signal. The second station uses the synchronization signal to maintain synchronization for demodulating the data signal.

Method of controlling synchronization signal power in a communication

In a mobile radio communication system, at a transmitter side, when a sound-absent section is detected in sound data, transmission of the sound data is stopped, and instead, tail bits are transmitted. A transmission power is lowered to 0 (zero) or a given value other than 0 when the transmission of the tail bits is finished. The lowering of the transmission power is held until a sound-present section is detected. Convolutional encoding is effected to the sound data and the tail bits prior to transmission. At a receiver side, the variation in transmission power is monitored to control an operation of an associated component in response to the monitored power variation. Viterbi decoding is effected for decoding the convolutional code.

Mobile radio communication system

There is disclosed a spread code generation device for spread spectrum communication wherein an input data is modulated so as to be spread by a spread code having a first period. The device includes a long period PN code generator for generating a spread code having a second period longer than the first period, an initial state register for storing an initial phase of the spread code having the first period output from the long period PN code generator and for outputting the initial phase to the long period PN code generator, and a counter for receiving and computing the spread code output from the long period PN code generator and for outputting a trigger signal to the initial state register when the computed spread code reaches the first period. The initial state register outputs the initial phase to the long period PN code generation in response to the trigger signal from the counter. The long period PN code generator is reset to the initial phase when the initial phase is input to the long period PN code generator, whereby the spread code having the first period is output from the counter.

Spread code generation device for spread spectrum communication

A code-division multiple-access system has a downstream channel for transmission from a base station to a number of mobile stations, and an upstream channel for transmission from the mobile stations to the base station. On the downstream channel, each mobile station's spreading code is divided into two parts, which modulate data transmitted on in-phase and quadrature carriers, respectively, thereby enabling the length of the spreading code to be doubled without increasing the chip rate. On the upstream channel, as soon as a symbol is received from one mobile station, it is despread to estimate its value, then respread and canceled as interference with respect to the other mobile stations, these processes being iterated in a cyclic order of the mobile stations.

Code-division multiple-access system with improved utilization of

In a block-spreading code-division multiple-access communication system a demodulator stores received chip data in a separate memory area for each transmitting station. Each area has a capacity of at least two blocks. When a complete block is received from a transmitting station, all blocks of data stored in the corresponding memory area are correlated against a set of product codewords, which are obtained by spreading a set of orthogonal codewords by the transmitting station's spreading code, to find the codeword that gives the maximum correlation value. For the oldest block, this correlation value and information identifying the codeword are output. For all blocks, the maximum correlation value and corresponding product codeword are used to calculate interference correction data, which are subtracted from the data in other memory areas.

Block-spreading code-division multiple-access demodulator with improved

A code-division multiple-access spread-spectrum communication system uses pairs of spreading codes with rates of N/2 chips per data symbol to provide a capacity equivalent to that obtained in a conventional system with N chips per symbol. In the transmitter, identical input data are spread in parallel by both spreading codes, then used to modulate two orthogonal carrier signals, and the resulting radio-frequency signals are combined for transmission from an antenna. In the receiver, the received signal is demodulated by parallel multiplication with the two carrier signals, the resulting baseband signals are correlated with the two spreading codes, and the results are added.

Code-division multiple-access communication system providing enhanced

A demodulator for code-division multiple-access spread-spectrum communications stores received chip data in a separate memory area for each transmitting station. Each area has a capacity of at least two symbols. When a complete symbol is received from a transmitting station, all chip data stored in the corresponding memory area are correlated with the corresponding spreading code, and estimated symbol values are derived from the correlated values. The correlated or estimated value of the oldest symbol is output as a demodulated value. The difference between each estimated symbol value and the previous estimate for the same symbol is multiplied by the spreading code to generate remaining interference values, which are subtracted from all chip data stored in memory areas for other transmitting stations, thereby updating those data.

Code-division multiple-access demodulator with improved interference

A three-dimensional image generator generates a random signal which it filters in two dimensions generate a realistic three-dimensional image of a natural object such as ocean waves or clouds. By performing the filtering operation repeatedly on overlapping intervals of the random signal, related images can be obtained to generate moving scenes at real-time rates. Two or more partial image generators can be connected in parallel to generate different directions of motion, or different parts of a complex scene. Within each partial image generator, two or more space filters can be connected in parallel to generate superimposed patterns, such as small ripples superimposed on large waves. This image generator is much faster than previous, fractal image generators.

Three-dimensional image generator

An LPC analyser calculates LPC coefficients using signals bandlimited to half the sampling frequency of the LPC coefficients to be calculated. Thef calculated LPC coefficients are continuous in time scale and free from aliasing distortion. A bandlimiting circuit suitable for use in the LPC analyser is also disclosed.

Linear predictive coding analysing apparatus and bandlimiting circuit

A circuit for pattern matching on the frequency axis which inlcudes a first transformation section having an adaptive filter which is generally identical to an adaptive finite impulse response filter, but with its delay elements having been replaced by all-pass filters. The first transformation section performs frequency transformation on an input signal and is characterized by utilizing as tap coefficients for the adaptive filter, linear predictive analysis coefficients of the input speech signal. The first transformation section outputs linear predictive analysis coefficients of the frequency transformed input signal. A second transformation section is similar to the first transformation section but the tap coefficients of its adaptive filter are linear predictive analysis coefficients of a reference speech signal. A control section calculates a distance between the respective linear predictive analysis coefficients output from the first and second transformation sections, calculates controlling parameters of the filters of the all-pass filters of the transformation sections so as to minimize this distance, and generates a pattern matching residual output on the frequency axis.

Pattern matching system

In a method of compressing text data including codewords of characters, an input word each composed of a series of codewords of one or more characters is extracted from the text data, a dictionary containing, as entries, words made up of characters is provided, a codeword is stored in association with each word, occurrence counts of respective words are also stored, the dictionary is searched to find whether or not the input word matches any of the words, the codeword assigned to the word which the input word has been found to match is produced, the occurrence count of the word which the input word has been found to match is updated; and when the input word is not found to match any of the words, the input word is introduced as a new word.

Data compression method

An error control encoding method and a mobile data communication system using the method in a moving body communication system such as mobile telephone for effecting data communication through a fading channel dominated by a burst error, upon receiving data transmitted from the transmitting side on the receiving side, detects any error involved in said received data as a frame error rate involved in block data or a bit error rate in the block data and thereby changes the frame length in response to the detected error rates. The mobile data communication system employs the error control encoding method wherein a frame length employed in the transmitting part is changed in response to the extent of any involved error in the received data detected by the remote receiving part.

Error control encoding system

An error correcting encoding method and a vehicle data communication apparatus based on the same for use in data communication via fading communication channels dominated by burst errors in the data communication among vehicles such as automobiles are disclosed. The error correction encoding method detects, as data sent from a transmitting side is received by a receiving side, any error contained in the received data as a frame error rate of error frames involved in block data or a bit error rate of error bits involved in the block data and selects an error correcting code in response to the frame error rate for encoding. The vehicle data communication apparatus according to the present invention profitably employs the method, and changes an error correcting code to be used on the transmitting side in response to the extent of errors involved in the received data detected by the receiving side of a remote apparatus.

Growing community of inventors

Tokyo, Japan

Takuro Sato