Fujitsu Corporation

Tadayuki Takada

Katsumi Fukumitsu

Masato Nagayama

Katsuji Yamaguchi

Haruki Watanabe

Kenichi Shinmura

A terminal apparatus by which, even where BER data, for example, of an optical signal of an existing wavelength cannot be utilized, the optical output powers of the existing wavelength and an extension wavelength can be adjusted in a short period of time while eliminating quality degradation of the existing circuit. The terminal apparatus includes a level controlling section for controlling a total optical output power of an existing wavelength signal light and an extension wavelength signal light to a fixed level, a monitoring unit capable of monitoring the optical output power for each wavelength, and a controller for controlling the optical output power of the extension wavelength signal light so that the optical output power of the existing wavelength signal light monitored by the monitoring unit may not be lower than a minimum permissible optical output power.

Terminal apparatus and controlling method for optical output power

For wavelength division multiplexing transmission, a standby-system processor capable of handling all wavelengths is included in relation to a plurality of working system processors associated with different wavelengths. If any of the plurality of working system processors fails, the wavelength of a light wave to be processed by the standby-system processor is controlled according to the wavelength being handled by a current- system processor that has failed. A switching unit switches the working system processor that has failed to the standby-system processor.

Wavelength division multiplexing transmitter receiver, optical

In a synchronizing system searching for k sub-frame patterns respectively distributed in k sub-frames in one frame of data transmitted via a transmission line where k is an integer, a frame pattern detection unit sequentially detects one of the k sub-frame patterns with a predetermined period. A control unit causes the pattern detection unit to detect an (i+1)th sub-frame pattern at the predetermined frame period after the pattern detection unit detects an ith sub-frame pattern where i=1, 2, . . . , k.

Hunting sub-frame patterns distributed in sub-frames of a transmission

An error counting circuit is adapted to count a number of code errors of a main signal in an external apparatus which is coupled to an optical transmission path. The error counting circuit includes an error counter which counts error pulses received from the external apparatus and indicative of the number of code errors of the main signal in response to clock pulses having a predetermined period and outputting a counted value for each the predetermined period, and a mechanism for stopping a counting operation of the error counter when a power failure of the external apparatus occurs, so that an erroneous counting operation of the error counter is prevented.

Error counting circuit

In a word synchronous system for a word interleave method in a digital communication system, the word synchronous system includes a line demultiplexing unit that receives a higher order signal for demultiplexing lower order signals therefrom; a window generating unit operatively connected to the line demultiplexing unit for generating windows to demultiplex the lower order signals from the higher order signal in the line demultiplexing unit; and a plurality of sub-demultiplexing units operatively connected to the line demultiplexing unit for receiving corresponding lower order signals from the line demultiplexing unit; wherein the window generating unit receives any one of lower order signals from the line demultiplexing unit and performs the detection of frame synchronous words from said lower order signal, when the window generating unit detects any one of frame synchronous words, the window generating unit performs a bit shift operation for the window in such a way that the bits are immediately shifted to the frame synchronous word to obtain synchronization with the window.

Growing community of inventors

Kawasaki, Japan

Tadayuki Takada