Fujitsu Corporation

Kosugi, Toru

Miyaou, Hirohisa

Furukawa, Takahiro

Toru Kosugi

Takahiro Furukawa

Yoshitaka Taki

Hirohisa Miyaou

Masayuki Tanaka

Katsuichi Ohara

Minoru Ishikawa

Katsutoshi Miyaji

Isao Chiku

Takenao Takemura

Satoshi Ohwada

Makoto Aoki

Yuichi Hashimoto

Yoshihiro Yatagai

Tamio Oonuma

Kouichi Sugama

A method for a path trace check reducing a load on a computer, raising the speed of the check, and easily enabling an increase of nodes to be added. On a sender side, a first computer simply generates path trace data, adds a specific code CR to this, multiplexes this to the transmission data, then transmits the same to a transmission line. On a receiver side, a second computer simply generates an expected value of the path trace data, autonomously compares this expected value and the actual path trace data extracted from the received transmission data by using the specific code, and determines coincidence of the two.

Method and apparatus for path trace check

A digital communication network has a first end office which includes a first multiplexer unit and a second end office which includes a second multiplexer unit. The network performs transmission and reception of multiplexed signals between the first end office and the second end office. A monitor unit is provided within the first end office. Monitoring is performed of the accuracy of the signal received by the second end office from the first end office, signal accuracy information with regard to the received signal being included as subsignalling information in the input signal Sin which is input to the first end office from the second end office. The subsignalling information is extracted by the monitor unit from the input signal, so as to enable monitoring of the signal accuracy of the input signal. The result is a significant improvement in the improvement of transmission quality monitoring service provided in the digital communication network.

Transmission quality monitoring system for a digital communication

A digital cross connect system includes reception interface parts for converting an input line signal into a VT signal having a VT frame format in conformance with synchronous optical network (SONET) standards, a switching part for cross connecting the VT signal received from the reception interface parts, and transmission interface parts for converting the cross connected VT signal received from the switching parts into a line signal. The reception interface part inserts a frame synchronizing signal within a reserved path overhead part of the VT signal, and the transmission interface part achieves frame synchronization of the VT signal in response to the frame synchronizing signal.

Digital cross connect system

A zero string error detection circuit which detects a specified number of zeros occurring in succession in bipolar data. The detection circuit has a relatively small gate size achieved by making the shift registers in the B8ZS or B6ZS code conversion circuit serve also for zero string monitoring. The zero string error detection circuit includes a pair of shift registers which receive serial bipolar data and convert it to parallel data composed of a specified number of bits, a code detector which, upon detecting a specific code from the parallel outputs of the shift registers, issues a reset signal to the shift registers to make the outputs of the shift registers zero, a zero string monitor which issue a zero string error detection signal when the outputs of the shift registers become zero, and a gate which inhibits the zero string monitor from issuing the zero string error detection signal during a specific period when the code detector issues a reset signal.

Zero string error detection circuit

A B8ZS.B6ZS coding circuit commonly used for a B8ZS coding or a B6ZS coding, generating a B8ZS violation signal or a B6ZS violation signal at a same start timing, and formed by a smaller circuit. The B8ZS.B6ZS coding circuit includes a first eight-bit shift register, receiving the input unipolar signal and shifting the same in response to a clock signal, the last two flip-flops in the shift register being reset under the B6ZS mode, a first gate outputting a first consecutive zero detection signal when all flip-flops in the first shift register are reset, a second seven-bit shift register, the last two flip-flops in the shift register being reset under the B6ZS mode, a second gate outputting a second consecutive zero detection signal when all flip-flops in the second shift register are reset, a third gate outputting an exclusive OR signal of the first and the second consecutive zeros detection signals, an inverter and outputting an inverted signal of the output from the third gate, a fourth gate receiving outputs from a sixth flip-flop in the first shift register, first, second, fourth and fifth flip-flops in the second shift register, and outputting a first original coded signal, and a fifth gate receiving outputs from the sixth flip-flop in the first shift register, the inverter, and the first, fourth and fifth flip-flops in the second shift register, and outputting a second original coded signal.

Bipolar with eight-zeros substitution and bipolar with six-zeros

A digital data multiple conversion system which can be used in a digital data communication network and recover lost clock pulses. The system includes a memory unit storing input data having N bits, a first frequency divider frequency-dividing an input clock having a first frequency at N to output a first frequency-divided signal, a first pulse width expansion circuit connected to receive m frequency divided pulses from the first frequency divider, where m indicates the number of lost pulses of the input clock plus one receiving the input clock, and outputting a first pulse width expanded signal of the input clock having an m+1 pulse width, a circuit outputting a read clock having a second frequency near to the the first frequency and stuffing the read clock, a second frequency divider frequency-dividing the read clock at N to output a second frequency-divided signal, a second pulse width expansion circuit connected to receive n frequency divided pulses from the second frequency divider, where n indicates the number of lost pulses of the read clock plus one, receiving the read clock, and outputting a second width expanded signal of the read clock having an n+1 pulse width; a phase detector outputting a phase detection signal when the phases of both pulse width expanded signals coincide, and a stuffing request circuit outputting a stuffing request signal to the stuffing circuit. The stuffing circuit stuffs the read clock in response to the stuffing request signal.

Digital data multiple conversion system for converting data having a

A system for controlling a change of sequence order of channel data for a telecommunication terminal device including: a plurality of channel boards provided to a terminal device and each having transmitting and receiving portions; a multiplexing portion for multiplexing data sent from the channel boards so as to generate transmission data; a demultiplexing portion for demultiplexing reception data so as to send it to the channel boards; and a sequence order address signal generator for generating a sequence order address signal to a memory. The system includes a memory for receiving the sequence order signal and capable of rewriting data for changing a sequence order of channel data; a memory wire control portion for controlling data write access for the memory; and a channel pulse conversion portion for receiving data read out from the memory and for generating a channel pulse corresponding to the data read out from the memory, in which a data communication sequence order between the channel boards and the multiplexing portion is determined by the channel pulse.

Growing community of inventors

Yokohama, Japan

Toru Kosugi