Fujitsu Corporation

Hitachi, Ltd.

Oki Electric Industry Co., Ltd.

Nippon Electric Co., Ltd.

Nippon Telegraph and Telephone Public Corporation

Takuhito Kojima

Hiroshi Ishikawa

Yasuo Satake

Toru Masuda

Eiji Minamitani

Susumu Ohara

Yoshitsugu Watanabe

Shinichiro Yoshida

Yuji Hayano

An electronic exchange of the time division system type or the space division system type, employing electronic contacts, in which a U-junctor is connected to the switching network of the electronic exchange. The switching network program for controlling the connection of the switching network regards the U-junctor as a combination of an outgoing and an incoming trunk. The connection between the trunks, between subscribers or between each subscriber and each trunk in a special calling service is controlled by using the U-junctor and the switching network.

Network connection system

A digital pad switch inserted in each highway of a time-division speech network in which there are disposed on the backward side of the speech network time switches, each time switch reading out speech information from a speech memory in the order of the memory cell address, assigning a memory cell address by the output from a channel counter. The digital pad switch is arranged so that it may send out, under the control of a common control unit, a selected converted input signal corresponding to an input signal from the input to the digital pad switch, the converted input signal respectively having been attenuated as compared the input signal by predetermined amounts and also sending out a converted input signal corresponding to a zero level signal regardless of the magnitude of the input signal. When cutting off a speech path set up in the time-division speech network, the digital pad switch is controlled by the common control unit so that the digital pad switch sends out the zero level signal as a signal of the speech path passing through the digital pad switch, and after writing the zero level signal in the speech memory of the time switch on the backward side, the speech path is cut off. A continuous tone signal passing through the time-division speech network is inputted into the digital pad switch. The digital pad switch is controlled by the common control unit to selectively send out the zero level signal for a desired period of time, thereby turning ON and OFF the tone signal. When sending out a howler tone, the amount of attenuation of the tone signal is decreased under the control of the common control unit in a stairstep manner. When testing a multi-frequency signal receiver, a multi-frequency signal transmitter and the multi-frequency signal receiver under test are connected to the backward and the forward side of the time-division speech network, respectively. A path is set up between them and then a signal on the path is attenuated variously by the digital pad switch in order to vary the level of the input signal to the multi-frequency signal receiver. Thus, the present invention permits efficient use of the digital pad switch.

Digital audio signal control system for a timedivision switching system

A line concentrator for a time division data switching exchange. Asynchronous and synchronous data signals generated at asynchronous and synchronous data terminals are subjected to known multi-point and synchronous sampling to become a train of bit-multiplexed first asynchronous and synchronous data channel signals. Responsive to a train of bit-interleaved read-in pulse groups timed relative to the respective synchronous data signals, an arithmetic unit stores the data channel signals in an octet memory according to the asynchronous and synchronous data terminals. Responsive to a train of read-out pulses appearing for the respective data terminals, the arithmetic unit reproduces groups of uninterleaved data channel signals for each data terminal and composes the reproduced data channel signals into a train of second asynchronous and synchronous data channel signals given by a common and uninterleaved bit format. The line concentrator is readily modified for decomposition of a train of asynchronous and synchronous data channel signal groups of the bit format into replicas of the original data signals.

Line concentrator for dealing with asynchronous and synchronous data

Growing community of inventors

Yamato, Japan

Takuhito Kojima