Fujitsu Corporation

Kabushiki Kaisha Toshiba

Hiroyoshi Mori

Kazuhiro Sato

Yoshimi Iijima

Tadao Ishii

Susumu Akizuki

Kazunori Ishida

Shigetaka Sawa

Akihisa Ogino

In a routing control apparatus and method for a composite network, a decision is automatically made as to whether a connection to a public telephone network via a leased line is allowed, by examining the dial information entered from a calling party and judging the communications applicable to the receiving node, the type of communication requested, and other factors. A connection judging unit extracts, from the dial information entered by the calling party, a node identifier CC for specifying the receiving node and a connecting type identifier V/F for directing the initiation of judgment as to whether a connection to a public network via a leased line is allowed and for providing a parameter for determining the type of communication requested, and which judges, based on the extracted identifiers CC and V/F, whether a connection to a public telephone network accommodating the called party is allowed via a leased line destined for a receiving node. When it is judged that connection to the public telephone network via a leased line is allowed, the call form the transmitting node is connected via the receiving node to the public telephone network that accommodates the called party.

Apparatus and method for routing control for composite network

An RF modulator according to this invention is constructed so as to allow channel setting without a test pattern generator. Specifically, the RF comprises an A/D converter for digitizing the TV channel setting data, an oscillator control circuit for controlling both the audio carrier oscillation and the RF carrier oscillation on the basis of the channel setting data digitized by the A/D converter, a signal adder for combining the video signal amplitude-modulated at the frequency of the RF carrier oscillation with the audio signal frequency/amplitude-modulated at the frequency of the audio carrier oscillation, channel picking-up means for picking up a portion near the center of each channel in the channel setting data, and a clipper circuit for cutting of the video signal at both ends of each channel setting range that have not been picked up by the channel picking-up means.

RF modular requiring no test pattern generator

A call meter signal receiver is provided for a subscriber's private metering system operated by a call meter signal sent from a central office. The receiver is operable both by common mode and normal mode signals. The receiver is small sized and can be installed in a central office trunk of private branch exchanger equipment. The call meter signal receiver is composed of a frequency tuned receiver including two buffer circuits, the first one for receiving the common mode and the second one for receiving the normal mode signal. The first buffer circuit is connected to the input side of a hybrid circuit of the COT, and has a high impedance, while the second buffer circuit, for receiving the normal mode signal, is connected to one of the output terminals of the hybrid circuit, and has a high impedance for voice signals. The outputs of these buffer circuits are fed to the frequency tuned receiver composed of a phase locked loop, of which frequency is tuned to 50 Hz, 12 kHz or 16 kHz by switching an externally attached circuit composed of a capacitor and resistors.

Call meter signal receiver for subscriber's private metering of

A communications system for transmitting and receiving data and voice signals simultaneously on 2-wire signal lines, which superposes and extracts high frequency modulated data signals using a high frequency transformer which is coupled to the 2-wire signal line. The transformer has two windings which are short-circuited with respect to high frequency components, but which pass low frequency voice signals between the 2-wire signal line and a low frequency hybrid circuit.

Communications system for transmitting and receiving data and voice

An overcurrent protection circuit including a first transistor, a second transistor, and an integrator. The first transistor operates to control a current flow from a power source to a load. The second transistor is turned on when an overcurrent flows through the first transistor. The overcurrent is detected by watching the collector-emitter voltage of the first transistor. Thus, the second transistor operates to bypass the base current to be supplied to the first transistor with a certain delay time defined by a delay part, which enables an instantaneous overcurrent to be ignored.

Growing community of inventors

Yokohama, Japan

Hiroyoshi Mori