Hitachi, Ltd.

501 Hitachi, Ltd.

Masahiro Takahashi

Takuji Hamada

Seiichi Yasumoto

Sadao Mizokawa

Hitoshi Fushimi

Hiroshi Gotoh

Masaaki Takizawa

Yoji Shibata

Jun Furuya

Kiyoshi Ishida

Iwao Ishinabe

Kenji Yokoi

Katsumi Mikamo

Toshiaki Watanuki

Yoshinobu Matsubayashi

Takushi Yoshimaru

Masakazu Okada

Ken Onuki

Katsuhiko Yoneda

Kozo Nakamura

Kotaro Hirasawa

Jushi Ide

Yoshinori Ohkura

Norifumi Yanai

Hideaki Masuko

Toshihiko Uchiyama

Hiroshi Tomizawa

Masao Yanaka

Seizi Maruo

Shinichi Ueda

Radio relay system

A television telephone including a movable head section, a support section and a bottom section. The movable head section includes an imaging device for inputting images and a display for displaying images. The bottom section includes a communication controller for transmission and reception of encoded information of at least one of audio and visual signals to and from a communication network, and a telephone controller for controlling transmission and reception functions and including a key console unit. The support section serves for connecting the bottom section and the movable head section and for supporting the movable head section and includes an image encoder/decoder for encoding image input signals and for decoding received image signals.

Television telephone

In a telemeeting terminal for performing communication between remote locations by using multiple media, the other party of a meeting is identified in a display picture and thereafter switching to a principal picture for presenting and explaining materials meeting is performed. As a result, it is possible to keep materials used in the meeting secret.

Multimedia telemeeting terminal device, terminal device system and

In an annular transmitting system including a ring-like transmission path realized by interconnecting serially a plurality of transmission stations in an annular form, at least one of the transmissions stations generating repetitively a transmitting frame constituted by a plurality of transmission units referred to as time slots, the frame being circulated along the transmission path, wherein transmission of information among transmission stations is performed in such a manner in which each of the transmission stations having a request to send information inserts the information in the slots by dividing the information, which information is ultimately fetched by the transmission station destined to receive that information, a multi-slot access system in which each of the time slots is provided with an area indicating whether the associated time slot is 'free' or 'busy', wherein the transmission station having a request to send information determines that the sending of the information is enabled when it is detected that one time slot located at a particular position within the transmitting frame is 'free' or when it is detected that the time slot succeeding immediately to the 'busy' slot is 'free', to thereby set successively those usable time slots which succeed to the detected 'free' time slot to the 'busy' state and insert the information in these usable time slots.

Multi-slot access system

A ring network data transmission system includes a plurality of transmission apparatuses, at least one terminal connected to each of the transmission apparatuses and double ring transmission paths interconnecting the transmission apparatuses in a ring-like system configuration so that terminals can communicate with one another through the associated transmission apparatuses. When a transmission fault occurs in the network, the transmission apparatus which can serve as the master station issues to all of the other transmission apparatuses a command for searching the fault location. In response to the reception of the command, each of the other transmission apparatuses sends out a monitor signal containing its own address and at the same time checks monitor signal received. Through collation of the address contained in the received monitor signal with the address information arrayed in the order in which the transmission apparatuses are interconnected, the number of bypassed transmission apparatuses existing between each transmission apparatus and the transmission apparatus sending out the monitor signal is determined. By comparing this number with a predetermined maximum permissible number of the stages allowable to be bypassed, the faulty location is detected. With such an operation, automatic reconfiguration operation of double ring configuration can be stabilized.

Method and apparatus for detecting a fault in a ring network data

A loop transmission system having a plurality of data processor connected through respective transmission station with a common loop transmission line is disclosed. This system has a concentrator connected with a plurality of transmission stations through respective loop transmission lines. The concentrator changes the order of connection said loop transmission lines thereby to change the order of connected of said transmission stations on said loop transmission lines.

Loop transmission system having plural stations connected in a variable

A looped data transmission system has a pair of looped transmission lines forming two transmission systems having different transmission directions, and a plurality of stations including at least one control station connected to said transmission lines of the two transmission systems. If a fault occurs in the two transmission lines of the two transmission systems in the same section, a loopback configuration is established such that stations adjacent to the faulty section send signals from one system back to the other system. With the loopback configuration being established, the stations which have received supervisory signals sent from a loopback end station send them back to the transmission line of the other system. When one of the loopback end stations has received a supervisory signal from the direction of the faulty section, it is judged that a portion of the faulty section is recovered, and the result of the judgement is communicated to the control station.

Method of detecting recovery from fault in a data transmission system

A loop type data transmission system based on a token pass principle, wherein a station whose transmission of data is completed passes therethrough a token to the stations located downstream. The station demanding the transmission acquires the right of transmission when received the token, to perform data transmission with a given station. The token signal is classified into a free token representative of the freedom of the line and a busy token representative of occupation of the line. Among a plurality of stations, only one station is destined to execute detection of transmission failure and remedy thereof. This one station is adapted to convert the free token detected upon reconstitution and repeating of the received information into the busy signal and subsequently re-send the free token. The station having sent out the free token after the completed data transmission is transferred to the state for reconstituting and repeating the received information when the busy token returns to that station.

Loop type data transmission system

This invention discloses a loop-back control method for loop-type data transmission systems in which, when a trouble occurs on both transmission lines of two systems, two stations adjacent to the trouble region return signals toward a control station in response to a command from the control station, thereby to separate the trouble region and continue the operation. According to this invention, when the control station detects the occurrence of a trouble on the transmission lines of the two systems, it sends out a broadcast command to search for the trouble point to the transmission lines of both systems and thereafter a loop-back command is issued so that the stations adjacent to the trouble point can loop-back the transmission.

Reconfiguration control method for a loop-type data network

A dual loop type data highway system comprises a data highway having at least two loops for data transmission and reception, a plurality of data transmitting/receiving stations serially connected to the data highway and a control station serially connected to the data highway. The data transmitting/receiving stations each have means for detecting the beginning of a transmission cycle, one for each of the loops, and the control station has, one for each of the loops, means for detecting the end of the transmission cycle and means for permitting the transmission/reception of data between specified two of the data transmitting/receiving stations during the transmission cycle by polling, whereby an effective transmission rate is increased without considerable increase of hardware.

Dual loop type data highway system

The periodicity of an input signal is monitored by means of a re-triggerable one-shot multivibrator. When an input signal interruption is detected by the output of the multivibrator, the state of the input signal interruption is held to interrupt the transmission until a phase locked loop is demodulated. The transmission is not opened until the phase locked loop is brought into its synchronous state.

Loop type data highway system for data transmission

Various machines and apparatus equipped in an unattendet remote controlled station are associated with contact means through which the remote supervisory control for the operation of these machines and apparatus is carried out to a master station. Contact information provided by the individual contact means is assigned with an indication input type determined by a setting circuit provided for each of the indication input types. The contact information assigned any one of indication input types is stored in a memory circuit having a predetermined memory and holding function which is provided for each of the indication input types. Outputs from the memory circuits are ORed and thereafter converted into a predetermined transmission format, which is transmitted to the master station, thus completing an indication input signal processing. A predetermined number of the contact information is ganged into groups and all of the above-mentioned processes are carried out by processing the groups on a time division basis.

Indication input signal processing system for use in remote supervisory

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Hitachi, Japan

Masahiro Takahashi