Patent application number | Description | Published |
20100172653 | Optical Transmission System, Optical Transmitter for Optical Transmission System, and Optical Receiver for Optical Transmission System - An optical transmission system is provided in which the optimum operating point of a Mach-Zehnder interferometer, matched to the optical frequency of the light source on the transmitting side, can be set. The optical receiver ( | 07-08-2010 |
20110262136 | OPTICAL DIGITAL TRANSMISSION SYSTEM - An optical digital transmission system of the present invention newly defines one second negative stuff byte in an overhead area for accommodation of the client signals with multiplexing into the OTU frame, newly defines one third positive stuff byte in a corresponding tributary slot in a payload area for accommodation of client signals with multiplexing, newly defines stuff control bits that is used for decision of the use of the second negative stuff byte and the third positive stuff byte in three different places in the overhead area for client signal accommodation with multiplexing, performs control by using the newly defined stuff control bits when accommodation of the client signal with the third positive stuff byte or the second negative stuff byte is required, and performs stuff control without using the newly defined stuff control bits when accommodation of the client signal by the third positive stuff byte and the second negative stuff byte is not required. | 10-27-2011 |
20130004168 | CLIENT SIGNAL ACCOMMODATING MULTIPLEXING APPARATUS AND METHOD - In an apparatus for accommodating and multiplexing asynchronous client signals in which an idle signal is defined, the transmission side transmits client signals after synchronizing the client signals by inserting or removing, with reference to a specific client signal, an idle signal to/from the same type of another client signal, and in the receiving side, a PLL part is shared by recovering a clock from a client signal and distributing the clock for another client signal. | 01-03-2013 |
20130259481 | CLIENT SIGNAL MAPPING CIRCUIT AND MAPPING METHOD - A client signal mapping circuit for accommodating a client signal in a transmission frame, including: a buffer unit configured to temporarily store the client signal; a buffer used amount monitoring unit configured to report a used amount of the buffer unit; a stuff processing determination unit configured to compare the used amount of the buffer unit with a predetermined reference value, and a pseudo random sequence signal and the comparison result; an overhead insertion unit configured to add an overhead to the client signal read from the buffer unit to form a transmission frame; and a reading control unit configured to perform control for reading the client signal from the buffer unit based on determination by the stuff processing determination unit. | 10-03-2013 |
20130343749 | WAVELENGTH DISPERSION AMOUNT ESTIMATION METHOD, WAVELENGTH DISPERSION COMPENSATION CIRCUIT, AND RECEPTION DEVICE - A wavelength dispersion amount estimation method, a wavelength dispersion compensation circuit, and a receiving device which rapidly estimate and set a wavelength dispersion amount to compensate with high accuracy at the receiving device which compensates waveform distortion at an optical fiber transmission path. The wavelength dispersion compensation circuit includes an analog-digital converter which converts an optical analog waveform received from the optical fiber transmission path to a digital signal, a digital signal processor which compensates waveform distortion of the digital signal output from the analog-digital converter due to wavelength dispersion at the optical fiber transmission path with a dispersion compensation amount estimated with the wavelength dispersion amount estimation method, and a symbol clock extractor which extracts a symbol arrival timing clock of received data contained in the digital signal output from the analog-digital converter and outputs strength of the symbol arrival timing clock as the clock detection value. | 12-26-2013 |
20140016929 | METHOD FOR ESTIMATING AMOUNT OF WAVELENGTH DISPERSION, WAVELENGTH DISPERSION COMPENSATION CIRCUIT, AND RECEIVING DEVICE - A wavelength dispersion amount estimation method, a wavelength dispersion compensation circuit, and a receiving device which rapidly estimate and set a wavelength dispersion amount to compensate with high accuracy at the receiving device which compensates waveform distortion at an optical fiber transmission path. A wavelength dispersion compensation circuit includes an analog-digital converter which converts an optical analog waveform received from the optical fiber transmission path to a digital signal, a digital signal processor which compensates waveform distortion of the digital signal output from the analog-digital converter due to wavelength dispersion at the optical fiber transmission path with a dispersion compensation amount estimated with the wavelength dispersion amount estimation method, and a symbol clock extractor which extracts a symbol arrival timing clock of received data contained in the digital signal output from the analog-digital converter and outputs strength of the symbol arrival timing clock as the clock detection value. | 01-16-2014 |
20150333838 | OPTICAL RECEIVING DEVICE AND PHASE CYCLE REDUCTION METHOD - An optical receiving device receives an optical signal that has been modulated by means of phase modulation or quadrature amplitude modulation, converts the received optical signal into an electrical signal using coherent detection, and performs phase compensation on the converted received signal, and includes: a carrier phase estimation unit that estimates carrier phase errors in a received symbol string obtained from the received signal; a gain adjustment unit that performs gain adjustment on symbols input into the carrier phase adjustment unit; a phase cycle slip reduction unit that, by performing statistical processing on an output from the carrier phase estimation unit, detects general noise that causes a phase cycle slip, and reduces the phase cycle slip; and a phase compensation circuit that compensates carrier phase errors contained in the received signal using an output from the carrier phase estimation unit. | 11-19-2015 |
20150341138 | COHERENT COMMUNICATION SYSTEM, COMMUNICATION METHOD, AND TRANSMISSION METHOD - The estimation of an amount of chromatic dispersion using a training signal sequence is possible. A transmission method includes: a training signal sequence generation step of generating, as training signal sequences, a plurality of signal sequences having power concentrated in a plurality of frequency bands, the power concentrated at different frequency bands; a training signal sequence selection step of selecting at least one training signal sequence from among the plurality of training signal sequences generated in the training signal sequence generation step, a signal multiplexing step of generating a signal sequence obtained by time-division multiplexing the training signal sequence selected in the training signal sequence selection step with a transmission data sequence, and an electrical-to-optical conversion step of transmitting the signal sequence generated in the signal multiplexing step as an optical signal. | 11-26-2015 |