Tokyo Shibaura Denki Kabushiki Kaisha

Tokyo Shibaura Electric Co., Ltd.

Takeo Fukuda

Kiyoshi Urui

Kazuhiko Hanawa

Isao Tashiro

Hideaki Murayama

Michiko Haseyama

Kazuaki Kawabata

Tadashi Murayama

Telephones are coupled with data terminal equipments through data lines. The data lines are used to transfer the terminal data between the data terminal equipments and the telephones. Speech signals are transferred between the telephones and a PCM telephone exchange through speech lines. Control lines are used for transferring a time-division-multiplexed signal made of telephone control signals such as lamp energizing signals, and the terminal data, and also used for transferring another time-division-multiplexed signal made of function signals such as function key actuation signals and the terminal data. With such a connection, a speech signal is transferred between telephones through the PCM telephone exchange and speech lines and the terminal data are transferred through the control lines and the PCM telephone exchange.

Automatic telephone exchange system for both speech signals and data

There is provided a telephone exchange including a switching network, a plurality of interface circuits whose corresponding transmit/receive paths are connected to the switching network, a data generator connected to the interface circuits to sequentially generate state information indicative of the states of the interface circuits, and a control circuit for controlling the switching network according to an output data from the data generator. The data generator generates state-variation information when the state of the interface circuit is varied and the control circuit is responsive to the state-variation information from the data generator to cause the switching network to be set to a state corresponding to the above-mentioned state information.

Interfacing circuit status detection arrangement in a telephone exchange

A telephone exchange comprises a plurality of central office trunk circuits, a plurality of line circuits, a plurality of switching circuits coupled to transmission paths of the trunk and line circuits, a plurality of switching circuits coupled to the reception paths of the trunk and line circuits, a variable attenuator having one end coupled commonly to the switching circuits that are coupled to the transmission path, a conference circuit coupled to the variable attenuator and the switching circuits that are coupled to the reception paths, a control circuit which controls both groups of switching circuits and the variable attenuator in time-sharing fashion thereby to provide speech paths in time-sharing fashion between selected ones of the central office trunk circuits and line circuits and which controls in time-sharing fashion the attenuation factor of the variable attenuator for each speech path established. The telephone exchange further comprises another variable attenuator which is coupled between the conference circuit and the switching circuits coupled to the reception paths and whose attenuation factor is controlled by the control circuit in time-sharing fashion.

Telephone exchange with time shared speech paths and selectively

Data transmitted from a local terminal to a remote terminal is converted into such a diphase data signal that a data bit of binary '0' is represented by a signal with two transitions, and a data bit of binary '1' is represented by a signal with one transition. Data transmitted from the remote terminal to the local terminal is modulated by the diphase data signal of the local terminal, and delivered to the local terminal in the form of a diphase data signal. In the local terminal, the coded diphase data signal from the remote terminal is demodulated by the diphase data signal of the local terminal, and regenerated into the transmission data of the remote terminal.

Data transmission system

A switching apparatus comprising a switching circuit provided with a plurality of input terminals and a plurality of output terminals; a plurality of regenerative repeaters connected between the prescribed ones of said plural input and output terminals, the number of the regenerative repeaters being less than that of circuits through which signals of high error rate are expected to pass; and means for conducting signals from the prescribed input terminals to the output terminals directly or through the regenerative repeaters.

Switching apparatus selectively utilizing a regenerative repeater

This digital telephone conference system provides improved cancellation of reflective signals which cause echo-singing problems, such as caused by hydrid mismatches, for any number of telephone sets. Each telephone set is sequentially sampled for time sharing, and alternate samples are given opposite polarity signs before being summed, thereby making approximately half of the signals of opposite phase, for any number of telephone sets, for effective cancellation. Also, each member of the conference receives a sum signal of all telephone sets except his own.

Digital type telephone system having a conference function

An integrator consisting of a high gain D.C. amplifier, a voltage-current converter such as a resistor, and a feed-back capacitor. An unknown analog input voltage to be converted and two known reference analog voltages which have the same polarity as that of the input voltage to be converted are supplied to the voltage-current converter in the integrator through a first switching circuit having three switches. The output voltage of the integrator is supplied to a comparator. The comparator compares the integrated voltage with a fixed reference voltage and produces an output signal when both voltages are equal. A second switching circuit including one switch, a third switching circuit including two switches, and two capacitors respectively connected to the switches in the third switching circuit are provided between an output terminal of the integrator and ground. A voltage-current converter such as a resistor or a transistor circuit is connected between the input terminal of the D.C. amplifier and the interconnecting point of the second and third switching circuits. Each switch in the first, second and third switching circuits, is controlled by a switch control circuit. The switch control circuit includes counters, flip-flops, calculating circuits and delay circuits. A voltage corresponding to one of the two known reference voltages is stored in one of the two capacitors connected to the ground and a voltage corresponding to the other known reference voltage is stored in the other capacitor connected to the ground. A combined voltage of the input voltage and the voltage stored in one of the two capacitors and a combined voltage of one of the reference voltages and the voltage stored in the other capacitor are respectively integrated by the integrator. As a result thereof, a digital quantity representative of the ratio of the unknown input voltage and the difference between the two reference voltages is obtained by the switch control circuit.

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Yokohama, Japan

Takeo Fukuda