Abstract: As is described above, an optical wavelength division multiplexing and transmission apparatus according to the present invention has the configuration in which a plurality of slave racks coupling to a master rack can be additionally installed one after another with the master rack. Therefore, in cases where it is desired to expand a function of a transmitter and a function of a receiver due to the increase of a quality of information to be transmitted, the additional installation of the slave rack can be performed without exerting influence on a communication means installed in advance and currently used. Accordingly, it can be expected that the optical wavelength division multiplexing and transmission apparatus is adapted for the optical communication service which is more and more increased in the future.

Abstract: Light signals of first to n-th bands amplified en bloc undergo proper attenuation through an adjustable optical attenuator in conformance with attenuation in an optical fiber connected to input of an optical amplifying repeater apparatus, whereon the light signals are demultiplexed or separated into individual bands and amplified by first to n-th fixed-gain optical amplifiers (#1, . . . , #n) each having a high fixed gain in the respective bands to be subsequently multiplexed by an optical multiplexer and then sent out onto a transmission line. A monitoring light branching device extracts a part of light power of a specific monitoring wavelength, which is then fed to an adjustable attenuator control circuit which controls the attenuation factor of the adjustable optical attenuator so that the light power of the specific wavelength remains constant. The gain of the optical amplifying repeater apparatus at the specific wavelength can thus be determined.

Abstract: The optical transmission apparatus has a Mach-Zehnder optical modulator, a light source for applying an optical signal of a continuous light to the optical modulator, a driving circuit for inputting a driving signal into the optical modulator, a branching filter for taking out a part of an output optical signal, a photodiode for converting the taken-out output optical signal into an electric signal, a band pass filter for extracting a frequency component of a driving signal included in this electric signal, an error signal generator circuit for generating an error signal of a bias voltage that minimizes a value of the extracted frequency component, and a bias voltage control circuit for applying a bias voltage added with this error signal to the optical modulator.

Abstract: In the multi-value modulation apparatus, one optical intensity detecting unit detects optical intensity of a modulation optical signal generated by one optical modulation signal generating unit and output from the variable optical attenuator. The detected optical intensity is provided to the comparator. Another optical intensity detecting unit detects optical intensity of a modulation optical signal output from another optical modulation signal generating unit. The attenuator attenuates the optical intensity detected by the another optical intensity detecting unit, and provides it to the comparator. The output of the comparator is provided to the optical variable attenuator as a control signal. The variable optical attenuator controls optical intensity of the modulation optical signal based on the control signal.

Abstract: The optical amplifier apparatus comprises an optical amplifier (3) which amplifies an input signal light, an output detecting unit (5) which detects an output level of the optical amplifier, an output control unit (6) which controls an output level of the optical amplifier according to an output level detected by the output detecting unit (5), a gain inclination detecting unit (7) which detects a gain inclination relating to a wavelength of the optical amplifier, and a gain inclination control unit (8) which controls a gain inclination of the optical amplifier (3) according to a gain inclination detected by the gain inclination detecting unit (7).

Abstract: The optical amplifier apparatus comprises an optical amplifier which amplifies an input signal light, an output detecting unit which detects an output level of the optical amplifier, an output control unit which controls an output level of the optical amplifier according to an output level detected by the output detecting unit, a gain inclination detecting unit which detects a gain inclination relating to a wavelength of the optical amplifier, and a gain inclination control unit which controls a gain inclination of the optical amplifier according to a gain inclination detected by the gain inclination detecting unit.

Abstract: An optical repeater is provided between a first optical fiber transmission path and a second optical fiber transmission path having a zero-dispersion wavelength different from the first optical fiber transmission path. This optical repeater wave-converts a wavelength division multiplex signal input from the first optical fiber transmission path with respect to respective wavelengths thereof, and outputs the wave-converted signal to the second optical fiber transmission path.

Abstract: The optical amplifier apparatus comprises an optical amplifier which amplifies an input signal light, an output detecting unit which detects an output level of the optical amplifier, an output control unit which controls an output level of the optical amplifier according to an output level detected by the output detecting unit, a gain inclination detecting unit which detects a gain inclination relating to a wavelength of the optical amplifier, and a gain inclination control unit which controls a gain inclination of the optical amplifier according to a gain inclination detected by the gain inclination detecting unit.

Abstract: Light signals of first to n-th bands amplified en bloc undergo proper attenuation through an adjustable optical attenuator in conformance with attenuation in an optical fiber connected to input of an optical amplifying repeater apparatus, whereon the light signals are demultiplexed or separated into individual bands and amplified by first to n-th fixed-gain optical amplifiers (#1, . . . , #n) each having a high fixed gain in the respective bands to be subsequently multiplexed by an optical multiplexer and then sent out onto a transmission line. A monitoring light branching device extracts a part of light power of a specific monitoring wavelength, which is then fed to an adjustable attenuator control circuit which controls the attenuation factor of the adjustable optical attenuator so that the light power of the specific wavelength remains constant. The gain of the optical amplifying repeater apparatus at the specific wavelength can thus be determined.

Abstract: The optical transmitter comprises a light source which inputs continuous optical signal and a driving circuit which inputs driving signal to an optical modulator of Mach-Zehnder type. A photo coupler separates a part of the output of the optical modulator. A photo diode converts this part into electric signal. A band-pass filter and a pre-amplifier extract a frequency component of the driving signal contained in the electric signal. A mixer conducts synchronous detection between the driving signal and the extracted frequency component. Finally, a bias voltage control circuit controls a bias voltage based on a result of the phase comparison.

Abstract: An AWG (arrayed-waveguide grating/10A) divides input ports (11A1 to 11An+1−1) into 1 number of groups, each group comprising m number of input ports, and combines optical signals belonging to each of the groups. For example, the optical signals of wavelengths &lgr;1 to &lgr;m are input from the input ports (11A1 to 11Am) and output from an output port (12A1) as multiplex light. The multiplex light output in each of the groups in the above manner is input into a wave combination coupler (18A) and output to a transmission line (19A) as multiplex light of the optical signals of the wavelengths &lgr;1 to &lgr;n.

Abstract: Because the phase comparison of the light signal data row and the light clock signal, and the coding of the light signal by the light signal, are simultaneously conducted, the influence of the phase variation in the signal path is not affected in principle, and the optimum phase condition is automatically established/maintained, and thereby, the present invention operates as an all-light type light receiver by which the light data and light clock are reproduced. Further, because the electric signal used herein exists in the range from the DC to the frequency of the difference between the light signal data row and the light clock signal, problems peculiar to the high speed electric signal can be avoided.

Abstract: An optical receiver includes a soft-decision deciding means (7) for deciding an electric received signal according to a plurality of decision levels so as to output a multivalued decision signal, a demultiplexing means (5) for serial-to-parallel converting the multivalued decision signal so as to output a multivalued parallel signal, a soft-decision error correction decoding means (8) for making an error correction to the multivalued parallel signal based on reliability information so as to output an error-corrected parallel received signal and decision results indicating the decision of the electric received signal according to the plurality of decision levels, a probability density distribution estimation means (9) for estimating probability density distributions based on distributions of the decision results indicating the decision of the electric received signal according to the plurality of decision levels, and a decision level control means (10) for controlling the plurality of decision levels in the so

Abstract: Light signals of first to n-th bands amplified en bloc undergo proper attenuation through an adjustable optical attenuator in conformance with attenuation in an optical fiber connected to input of an optical amplifying repeater apparatus, whereon the light signals are demultiplexed or separated into individual bands and amplified by first to n-th fixed-gain optical amplifiers (#1, . . . , #n) each having a high fixed gain in the respective bands to be subsequently multiplexed by an optical multiplexer and then sent out onto a transmission line. A monitoring light branching device extracts a part of light power of a specific monitoring wavelength, which is then fed to an adjustable attenuator control circuit which controls the attenuation factor of the adjustable optical attenuator so that the light power of the specific wavelength remains constant. The gain of the optical amplifying repeater apparatus at the specific wavelength can thus be determined.

Abstract: The present invention relates to a display apparatus, a marker signal making process, a marker signal detector circuit, and a control signal generator circuit that are suitable for use when making a display in which a display screen is divided into a plurality of areas and images whose picture qualities are different at every area are displayed. Thus, in the present invention, image signals (R/G/B) from input terminals 1R, 1G, 1B are supplied to a preamplifier IC 3, e.g. to respective sharpness improving circuits 32R, 32G, 32B therein. Image signals derived from the preamplifier IC 3 are subjected to DC voltage conversion by a cutoff adjusting amplifier 6 and then supplied, e.g. to a cathode ray tube 7 as a display means. A microcomputer 40 which is present within this apparatus and controls various kinds of functions forms first and second DC voltage data for controlling, e.g. the sharpness.

Abstract: Light signals of first to n-th bands amplified en bloc undergo proper attenuation through an adjustable optical attenuator in conformance with attenuation in an optical fiber connected to input of an optical amplifying repeater apparatus, whereon the light signals are demultiplexed or separated into individual bands and amplified by first to n-th fixed-gain optical amplifiers (#1, . . . , #n) each having a high fixed gain in the respective bands to be subsequently multiplexed by an optical multiplexer and then sent out onto a transmission line. A monitoring light branching device extracts a part of light power of a specific monitoring wavelength, which is then fed to an adjustable attenuator control circuit which controls the attenuation factor of the adjustable optical attenuator so that the light power of the specific wavelength remains constant. The gain of the optical amplifying repeater apparatus at the specific wavelength can thus be determined.

Abstract: The optical amplifier apparatus comprises an optical amplifier (3) which amplifies an input signal light, an output detecting unit (5) which detects an output level of the optical amplifier, an output control unit (6) which controls an output level of the optical amplifier according to an output level detected by the output detecting unit (5), a gain inclination detecting unit (7) which detects a gain inclination relating to a wavelength of the optical amplifier, and a gain inclination control unit (8) which controls a gain inclination of the optical amplifier (3) according to a gain inclination detected by the gain inclination detecting unit (7).

Abstract: Light signals of first to n-th bands amplified en bloc undergo proper attenuation through an adjustable optical attenuator in conformance with attenuation in an optical fiber connected to input of an optical amplifying repeater apparatus, whereon the light signals are demultiplexed or separated into individual bands and amplified by first to n-th fixed-gain optical amplifiers (#1, . . . , #n) each having a high fixed gain in the respective bands to be subsequently multiplexed by an optical multiplexer and then sent out onto a transmission line. A monitoring light branching device extracts a part of light power of a specific monitoring wavelength, which is then fed to an adjustable attenuator control circuit which controls the attenuation factor of the adjustable optical attenuator so that the light power of the specific wavelength remains constant. The gain of the optical amplifying repeater apparatus at the specific wavelength can thus be determined.

Abstract: In the multi-value modulation apparatus, one optical intensity detecting unit detects optical intensity of a modulation optical signal generated by one optical modulation signal generating unit and output from the variable optical attenuator. The detected optical intensity is provided to the comparator. Another optical intensity detecting unit detects optical intensity of a modulation optical signal output from another optical modulation signal generating unit. The attenuator attenuates the optical intensity detected by the another optical intensity detecting unit, and provides it to the comparator. The output of the comparator is provided to the optical variable attenuator as a control signal. The variable optical attenuator controls optical intensity of the modulation optical signal based on the control signal.

Abstract: In a network computer system wherein the type of keyboard at a managing terminal is different from the type of keyboard at a managed terminal, keyboard scan code data from the keyboard at the managing terminal is first converted to virtual scan code data. Next, the virtual scan code data is converted to keyboard scan code data that is compatible with the keyboard at the managed terminal. This conversion, which uses two conversion tables that are selected from a plurality of conversion tables by detecting the different types of keyboards at the managing and managed terminals, permits the keyboard at the managing terminal to be of a different type than that at the managed terminal.