Kokusai Denshin Denwa Co., Ltd.

Secretary of Agency of Industrial Science and Technology

National Institute of Advanced Industrial Science and Technology

Yoshikazu Ikeda

Masanobu Fujioka

Yoichi Taguchi

Akihiro Oishi

Nobuo Furuya

Takashi Masuda

Ken-ichi Fujita

Hiromichi Mori

Atsushi Ito

Yasushi Wakahara

Kazuo Nakayama

Jun Matsumoto

Yutaka Ishigami

Hikaru Yagi

Tatsuo Maruyama

Hisae Nakahara

Shinichi Kinugasa

Nagao Ogino

Disclosed is a novel, high molecular weight aliphatic polyester having excellent mechanical strengths such as breaking strain and containing a copolymer structure with 3-alkoxy-1,2-propane diol and a method of producing the aliphatic polyester in an industrially advantageous manner. The aliphatic polyester is a biodegradable high molecular weight aliphatic polyester having an ester structure derived from 3-alkoxy-1,2-propane diol.

Biodegradable high molecular weight polyester and method of preparing same

Biodegradable aliphatic copolyester and method of preparing same

A process of producing a polyester or copolyester, wherein at least one cyclic lactone of the following formula (I):

Aliphatic polyester and process for the production thereof

A service processing system has a plurality of service processing nodes each having a single local data base, and a plurality of exchanges each of which is coupled user terminals. Said service processing nodes are coupled with one another through communication lines. A query by a user terminal is transferred to a local data base through an exchange to which the user terminal belongs. When a response to the query is stored in that data base, said response is directly given to the exchange from said local data base. On the other hand, when the local data base does not store the response the query of the user terminal is transferred to another service processing node which is designated by the local data base through the communication line between the service processing nodes. The response obtained in said other service processing node returns to the first local service processing node. Thus, the service to a user terminal is carried out by using a plurality of distributed data bases, each of which stores only local data.

Service processing system with distributed data bases

In a communication system which handles both a demand call, and a reservation call which appoints the start time and the end time of the communication, the reservation call must be connected at the desired time even if the circuits are full of the demand calls. The service process node which has a data base storing the information of the reservation calls, tries to connect the reservation call repetitively until the scheduled end time of the reservation call in every predetermined pause, if the circuits are full of the demand calls. Also, when it is anticipated that the circuits would be full at the desired time, the service process node suggests to the subscriber the alternative time for reservation.

Quasi reservation-based communication service process system

A local communication system among ISDN terminal equipment in a user's premises are connected to a local passive bus of the LSDN basic-access interface. The present system can establish the local communication through a network termination unit among ISDN termination equipment. In order to establish such a local communication, a multiframing scheme is taken on a passive bus forming multiframes by combining together the predetermined number of frames which are as defined in the I.400 series of CCITT recommendations. The network termination unit has a switching device for coupling two circuit-switched type communication channels (B1, B2) on the passive bus in one direction of transmission with the two other channels (B2, B1) in the other direction to establish local communication. Alternatively, the switching device couples the two channels on the passive bus with those on the subscribed line to establish external communication. Each of the terminal equipments has a device for requesting the local communication when required.

Local communication system among ISDN terminal equipments

The ISDN user-network interface is defined in the CCITT D-channel protocol recommendation (I-400 series recommendations), in which many kinds of communication terminals (e.g. faximile, telephone, teletex, etc.) can communicate through a subscriber line. The user-network interface is improved from the view point of effectiveness of terminal usage, provision of communication service, and, flexibility of system configuration, by providing a control terminal in the subscriber. The control terminal doubles as ordinary terminal equipment, and has a global control function for controlling other subscriber terminal equipment. The control terminal establishes and/or releases a local control phase in which a control terminal controls ordinary terminal equipment in the same subscriber to have them correspond to the communication with another subscriber using the means which belong to the ordinary terminal equipment inherently. The control terminal operates as an ordinary terminal apparatus when it is not in local control phase.

ISDN subscriber terminal control system

A PCM signal calculator for non-linear encoded PCM signals in the A-law system or .mu.-law system having a sign bit and a plurality of absolute value bits with three bits of segment number and four bits of step numbers within segment comprises; (a) a pair of input terminals for receiving the input PCM signals; (b) a signal or plurality of calculation means for providing the addition, subtraction and/or multiplication between the absolute values of two input PCM signals; (c) means for providing sign bit of the calculated result from the sign bits of the input PCM signals and/or the output of said calculation means; (d) an output terminal for providing the sign bit of the result from said means (c) and the absolute value of the result from said means (d). Said calculation means is either a table memory storing the result of each calculation according to the address designated by the input signals or combination of electronic components operating input PCM signals with segment number and step number within segment like a floating point number. Thus, the calculation of PCM signals encoded with non-linear encoding system like A-law and/or .mu.-law is performed without converting the PCM signals to linear signals.

PCM Signal calculator

An apparatus for detecting a tone signal in a telephone switching system is provided in which a calculation, in particular, multiplication is performed by a table look-up process in a digital memory, instead of using a conventional complicated multiplier. A tone signal of a particular frequency in a telephone line is detected through a discrete Fourier transform process (DFT), by the calculation of s(i)=x(iT).times.sin(i2.pi.fT), c(i)=x(iT).times.cos(i2.pi.fT), S=.SIGMA.s(i), C=.SIGMA.c(i), and P=S.sup.2 +C.sup.2. In the above calculation, the multiplication (x(iT).times.sin(i2.pi.fT), and x(iT).times.cos(i2.pi.fT)) is performed by a table look up method in a read only memory (ROM). Thus, the calculation is simplified. Further, the ROM has cells for only the discrete particular levels of multiplicands and/or the multipliers to reduce the capacity of the ROM, and the ROM is referred to by the multiplicand and/or the multiplier through the conversion of the same by a coefficient number generator.

Signal processing system using a digital technique

In a telephone switching system having a main-speech-path switch, connected to a plurality of subscribers and a plurality of board trunks, the connection in the main-speech-path switch is controlled as follows. In the first mode, the connection between a calling channel and one of the board trunks and the connection between a called channel and the board trunk are established through the main-path-switch, so as to selectively enable speech between an operator connected to said board trunk and one of a calling subscriber and a called subscriber. In the second mode, the connections between the calling channel and the called channel is directly established in the main-speech-path switch, while simultaneously connecting the two channels to the board trunk through the main-speech-path switch, so as to enable to monitor the speech between the calling subscriber and the called subscriber by the telephone operator. In the third mode, the main-speech-path switch effects only the connection between the calling channel and the called channel, while clearing the connection between said two channels and said board trunk. Thus, the main-speech-path switch is free from the board trunk except for the monitoring and the initial connection operation, and can increase the exchange capability.

Call processing system with an operator assistance in a telephone

In a transmission station, the information from each channel is sampled and encoded to a PCM form having a predetermined length of bits. The group of said bits together with line number bits is called a signal block. Only significant signal blocks from all the channels are transmitted to a receiving station through a buffer memory provided at a transmission station and a common transmission line. The receiving station receives the signal blocks through a buffer memory provided at the receiving station and inserts an idle signal to the portion where the transmission station removes a signal block due to an insignificant signal block. The received signal blocks are distributed to each receiving channel, thus, the original signal is reproduced at the receiving station.

Growing community of inventors

Tokyo, Japan

Yoshikazu Ikeda