Nippon Telegraph and Telephone Corporation

Akihiro Tanabe

Toshiaki Shitaba

Tomoaki Yoshida

Takashi Mitsui

Kengo Horikoshi

Yoichi Fukada

Hisao Yoshinaga

A signal converting apparatus includes a conversion unit, a measurement unit, and a control unit. The conversion unit performs FM batch conversion on an input signal containing a plurality of carrier signals, to generate an FM signal. The measurement unit measures the carrier levels of the plurality of carrier signals contained in the input signal, and the maximum frequency of the input signal. The control unit calculates the frequency deviation amount of the entire input signal, on the basis of the measured carrier levels of the respective carrier signals. Using the calculated frequency deviation amount and the measured maximum frequency, the control unit calculates a center frequency for the FM signal, and controls the conversion unit so that the center frequency of the FM signal to be generated by the FM batch conversion becomes equal to the calculated center frequency.

Signal converting apparatus and signal converting method

An apparatus includes a reception processing unit configured to output a frequency division multiplexed signal obtained from a transmission signal transmitted over the wired communication network, an output control unit configured to output, in a case that apparatus identifying data matches signal specifying data, a frequency band specifying data indicating a frequency band corresponding to the signal specifying data, the apparatus identifying data being for requesting signal quality degradation, and the signal specifying data specifying a carrier signal requesting signal quality degradation among a plurality of carrier signals included in the frequency division multiplexed signal, a disturbing signal generation unit configured to generate a disturbing signal in a frequency band corresponding to the frequency band specifying data output by the output control unit, and a multiplexing unit configured to multiplex the frequency division multiplexed signal and the disturbing signal to output.

Communication network terminating device, communication system, signal jamming method and signal jamming program

In an optical transmission system including a plurality of optical transmitting units and a relay device, the plurality of optical transmitting units include a frequency modulation conversion unit that converts an input signal into a frequency modulation signal through frequency modulation conversion processing, a multiplexing unit that multiplexes monitoring signals with different frequencies with the frequency modulation signal, and an optical modulation unit that converts the frequency modulation signal that is an electric signal in which the monitoring signals are multiplexed into optical signals having different wavelengths, and the relay device includes a photoelectric conversion unit that acquires a combined signal obtained by combining optical signals having different wavelengths from each other and converts the combined signal into an electric signal, and a measuring unit that measures transmission quality of the plurality of monitoring signals included in the electric signal.

Optical transmission system and transmission quality monitoring method

An optical transmission apparatus includes an input unit, a demultiplexing unit, a measurement unit, and a switching unit. The input unit inputs a first multiplexed signal and a second multiplexed signal each obtained by multiplexing a plurality of optical signals having different wavelengths. The demultiplexing unit demultiplexes the first multiplexed signal and the second multiplexed signal by wavelength. The measurement unit measures qualities of a plurality of optical signals obtained by demultiplexing the first multiplexed signal and qualities of a plurality of optical signals obtained by demultiplexing the second multiplexed signal. The switching unit performs switching between the first multiplexed signal and the second multiplexed signal to be output to a subsequent stage based on a result of measurement by the measurement unit.

Optical transmission apparatus and optical transmission method

An optical transmission apparatus of an embodiment is an apparatus for redundantly transmitting a multiplexed signal obtained by multiplexing N (N is an integer of 2 or greater) optical signals having different wavelengths, the apparatus including: a first demultiplexing unit to which a first multiplexed signal is input, the first demultiplexing unit configured to demultiplex the input first multiplexed signal into the N optical signals; N first detection units to which the N optical signals demultiplexed by the first demultiplexing unit are respectively input, each of the N first detection units configured to detect presence or absence of deterioration of a corresponding input optical signals of the input optical signals based on a signal level of the corresponding input optical signal; a second demultiplexing unit to which a second multiplexed signal is input, the second demultiplexing unit configured to demultiplex the input second multiplexed signal into the N optical signals; N second detection units to which the N optical signals demultiplexed by the second demultiplexing unit are respectively input, each of the N second detection units configured to detect presence or absence of deterioration of a corresponding input optical signal of the input optical signals based on a signal level of the corresponding input optical signal; and a selection unit configured to select, based on the detection result of presence or absence of deterioration of each of the optical signals by the first detection units and the second detection units, N optical signals having different wavelengths from either the optical signals demultiplexed by the first demultiplexing unit or the optical signals demultiplexed by the second demultiplexing unit.

An optical transmission system includes: a first optical transmitting unit for transmitting a first optical signal having a first wavelength; a second optical transmitting unit for transmitting a second optical signal having a second wavelength; an output adjustment unit for acquiring the first optical signal and the second optical signal, adjusting signal intensities of the acquired optical signals, and outputting the optical signals; a multiplexer for multiplexing the first optical signal and the second optical signal that have been subjected to signal intensity adjustment and outputting a multiplexed signal; an amplifier for amplifying the multiplexed signal; a first optical receiving unit for receiving the amplified first optical signal; and a second optical receiving unit for receiving the amplified second optical signal. The output adjustment unit adjusts the signal intensities of the first optical signal and the second optical signal such that the signal intensity of the first optical signal received by the first optical receiving unit is larger than or equal to a first predetermined value, and the signal intensity of the second optical signal received by the second optical receiving unit is larger than or equal to a second predetermined value.

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Musashino, Japan

Akihiro Tanabe