Abstract: A SDH receiver which comprises a first polarization beam splitter 11, a second polarization beam splitter 13, a first separator 15, a second separator 17, a third separator 19, a fourth separator 21, a first 90-degree polarization rotor 23, a second 90-degree polarization rotor 25, a first hybrid detector 31, a second hybrid detector 33, a third hybrid detector 35, a fourth hybrid detector 37, and a signal processor 39.

Abstract: A transmission apparatus including: a branch circuit that branches a signal including first data and second data superimposed on the first data into two signals; a limiting amplifier that amplifies one signal in the two signals; a linear amplifier that amplifies another signal in the two signals; a first detector that detects the first data from the amplified one signal; and a second detector that detects the second data from the amplified another signal and the amplified one signal.

Abstract: Methods and apparatus to realize high spectral efficiency in optical signals transmitted over long distances.

Abstract: An optical receiver that receives a wavelength-multiplexed optical signal is disclosed. The optical receiver implements two or more PD elements each receiving an optical signal contained in the wavelength-multiplexed optical signal, a switch that selects one of photocurrents output from the PD elements, an I/V converter that converts the photocurrent into a voltage signal by a variable resistor whose resistance is adjusted for respective photocurrent, and a digital-to-analog converter. The optical receiver estimates the power of the optical signals from look-up-tables correlating the power of the optical signals with the digitally converted photocurrents at the selected resistance of the variable resistor.

Abstract: A voltage controlled oscillator (“VCO”) circuit is disclosed. The VCO includes a switch module comprising a first transistor and a second transistor; a first LC-tank module, the first LC-tank module is operatively connected between the drain of the first transistor and the drain of the second transistor; and a second LC-tank module, the second LC-tank module is operatively connected between the gate of the first transistor and the gate of the second transistor, the source of the first transistor and the source of the second transistor are operatively connected.

Abstract: A method and apparatus for measuring a filtering characteristic, pre-equalizer and communication equipment. The apparatus for measuring a filtering characteristic includes: a first processing unit configured to determine a filtering characteristic of a receiving end according to an amplitude of a receiving signal obtained after a measurement signal passes through a transmitting end filtering module and a receiving end filtering module at provided different frequency offsets of a transmitting laser of a transmitting end and a local laser of the receiving end.

Abstract: Apparatus and method for transmitter alignment in an optical communication system are provided. In certain configurations, a method of correcting for transmitter skew is provided. The method includes generating an optical signal using a transmitter based on an in-phase (I) component and a quadrature-phase (Q) component of a transmit signal, the optical signal having a baud rate that is based on a timing tone. The method further includes receiving the optical signal as an input to a receiver, and generating a signal vector representing the optical signal using the receiver. The signal vector includes an I component and a Q component. The method further includes calculating a power of the timing tone based on processing the signal vector using a tone power calculator of the receiver, and correcting for a skew of the transmitter based on the calculated power.

Abstract: A power converter includes an energy transfer element and a circuit coupled to the input of the power converter. The circuit includes a switch and a control circuit capable of detecting whether an AC voltage source is coupled to the input, or uncoupled from the input within a first predetermined time. The control circuit is coupled to drive the switch in a first operating mode when the AC voltage source is coupled, drive the switch in a second operating mode when the AC voltage source is uncoupled, and is capable of discharging a capacitance coupled between input terminals of the power converter to a threshold voltage level through a discharge path and through the switch within a second predetermined time. An RC time constant of the discharge path is less than or equal to one second and the threshold voltage level is less than or equal to ten volts.

Abstract: A comparator includes a current mirror module, a comparison module and a buffering and outputting module. The current mirror module provides a bias current to the comparison module. The comparison module comprises a positive input end, a first negative input end and a second negative input end, the positive input end connects to an external terminal, the first negative input end and the second negative input end input a low threshold voltage and a high threshold voltage, respectively. The comparison module compares a voltage of the positive input end to the low threshold voltage and the high threshold voltage, and outputs a comparison result to the buffering and outputting module.

Abstract: Methods and systems for accurate gain adjustment of a transimpedance amplifier using a dual replica and servo loop is disclosed and may include, in a transimpedance amplifier (TIA) circuit comprising a first TIA, a second TIA, and a third TIA, each comprising a configurable feedback impedance, and a control loop, where the control loop comprises a gain stage with inputs coupled to outputs of the first and second TIAs and an output coupled to the configurable feedback impedance of the second and third TIAs: configuring a gain level of the first TIA by configuring its feedback impedance, configuring a gain level of the third TIA by configuring a reference current applied to an input of the first TIA, and amplifying a received electrical signal to generate an output voltage utilizing the third TIA. The reference current may generate a reference voltage at one of the inputs of the gain stage.

Abstract: Swept source optical coherence tomography (SS-OCT) systems and methods may employ down-conversion. Down-converter systems and methods may utilize a distribution element and a frequency down shifter. The distribution element may receive an output signal of a photo detection device, the output signal comprising a first frequency component at or below a maximum conversion frequency and a second frequency component above the maximum conversion frequency. The distribution element may send the first frequency component to an analog to digital (A/D) converter and send the second frequency component to a frequency down shifter. The frequency down shifter may down shift the second frequency component to a frequency at or below the maximum conversion frequency to form a down shifted second frequency component. The frequency down shifter may send the down shifted second frequency component to the A/D converter.

Abstract: A transceiver (4) comprising a receive part (70) configured to receive and detect a first signal carried on an optical carrier, wherein the signal is in a first part of a RF spectrum. The transceiver (4) further comprises a modulator (68) configured to modulate the same optical carrier with a second signal in a second part of the RF spectrum. The transceiver comprises a transmit part (60) configured to transmit the optical carrier modulated with the second signal. The first part of the RF spectrum is separate to the second part of the RF spectrum. The first signal and/or second signal are spectrally compressed signals.

Abstract: An Optical Line Termination (OLT) module and an OLT are disclosed. According to an embodiment of the OLT optical module, an optical signal receiver connects with a trans-impedance amplifier of which differential outputs connect with a limiting amplifier. An SD output of the limiting amplifier connects with a clock input of a D trigger and an input of a micro control unit. The D trigger connects with a control signal input of a first switch tube and may cause the first switch tube to be in conducting state when outputting high level. When the optical signal receiver detects an uplink burst signal, the limiting amplifier may generate the SD signal, the D trigger may output high level according to the SD signal and the first switch tube will be in conducting state, so that the micro control unit may detect the received optical power of the uplink burst signal.

Abstract: An optical network system comprising an optical line terminal (OLT) and an optical network unit (ONU) coupled to the OLT and configured to communicate with the OLT via an optical signal. At least one of the OLT or the ONU comprises a closed-loop gain controlled transimpedance amplifier (TIA) comprising a first amplifier configured to receive an input signal, generate a main output signal by amplifying the input signal according to a gain factor of the first amplifier, and generate an auxiliary output proportional to the input signal, an average detector coupled to the first amplifier and configured to receive the auxiliary output, and determine an average of the input signal according to the auxiliary output, and a feedback loop coupled to the first amplifier and the average detector and configured to control the gain factor of the first amplifier according to the average of the input signal.

Abstract: An optical data transmitter includes vertical cavity surface-emitting lasers and an all-optical spatial mode multiplexer. Each vertical cavity surface-emitting laser is configured to output a data modulated optical carrier at a center wavelength of less than one micrometer. The all-optical spatial mode multiplexer has an optical output and optical inputs. Each vertical cavity surface-emitting lasers is optically connected to one or more of the optical inputs of the all-optical spatial mode multiplexer. The all-optical spatial mode multiplexer is configured to cause at least two of the vertical cavity surface-emitting lasers to excite linearly independent combinations of one or more optical spatial propagating modes of an optical fiber in response to the optical output being coupled to a near end of the optical fiber.

Abstract: A method of controlling a parameter in the generation of a coherent optical signal, the method comprising the steps of: receiving a set of signal samples relating to detection of a coherent optical signal; transforming the set of signal samples into a set of spectrum samples in the frequency domain, the set of spectrum samples being an estimation of the spectrum of the coherent optical signal; calculating at least one feedback variable based on the spectrum samples; and adjusting the parameter based on the at least one feedback variable.

Abstract: A method for operating an electronic device is provided. The method includes converting received infrared into an electrical signal, amplifying the electrical signal and outputting an analog signal, converting the analog signal into digital data, determining whether the digital data is valid, and activating an application program in a freeze state to be in an unfreeze state.

Abstract: An optical receiver includes an APD that converts an input optical signal into a current signal, a TIA that converts the current signal output from the APD into a voltage signal, an LIA that shapes a waveform of the voltage signal output from the TIA, an AOC having a time constant switching function, the AOC automatically compensating for an offset voltage between differential outputs from the TIA, and a convergence-state detection circuit that outputs, after detecting convergence completion of the automatic compensation in the AOC, to the AOC, a time constant switching control signal for switching a time constant from a high-speed time constant to a low-speed time constant.

Abstract: A method for detecting a dispersed pulse in a received signal that has been dispersed by a dispersive medium includes obtaining an input array of cells, each indicating an intensity of a frequency component of the signal at a representative time. A fast dispersion measure transform (FDMT) is applied to concurrently sum the cells of the input array that lie along different dispersion curves, each curve defined by a known non-linear functional form and being uniquely characterized by a time coordinate and by a value of the dispersion measure. Application of FDMT includes initially generating a plurality of sub-arrays, each representing a frequency sub-band and iteratively combining pairs of adjacent sub-arrays in accordance with an addition rule until all of the initially generated plurality of sub-arrays are combined into an output array of the sums, in which a cell of the output array that is indicative of a transmitted pulse is identified.

Abstract: An optical transmitter includes an optical modulator to modulate light having a predetermined wavelength into an optical signal based on a data signal, a memory, and a processor coupled to the memory and the processor configured to modulate an input signal into a multi-carrier signal so as to generate the data signal, the multi-carrier signal including a plurality of subcarriers each to which a transmission capacity is allocated, acquire a first frequency distribution of an intensity of the multi-carrier signal, acquire a second frequency distribution of an intensity of the optical signal, control the modulating of the input signal into the multi-carrier signal to change a number of subcarriers of the multi-carrier signal, and control the optical modulator to adjust a modulation characteristic of the optical modulator so that a divergence between the first frequency distribution and the second frequency distribution is equal to or less than a predetermined value.

Abstract: An apparatus comprises a polarization-diversity optical hybrid that converts an optical signal into a plurality of optical signals comprising a first polarization component and a second polarization component orthogonal to the first polarization component, one or more detectors that convert the plurality of optical signals into a plurality of first analog electrical signals, DC blocking elements that remove DC signal components to output a plurality of second analog electrical signals, analog to digital converters (ADCs) coupled to the DC blocking elements that convert the plurality of second analog electrical signals into a plurality of digital signals, and a digital signal processing (DSP) unit coupled to the ADCs. The DSP is configured to perform a fiber dispersion compensation on the plurality of digital signals and add DC offsets to output a plurality of DC-restored compensated digital signals.

Abstract: Methods and systems for a distributed optoelectronic receiver are disclosed and may include an optoelectronic receiver having a grating coupler, a splitter, a plurality of photodiodes, and a plurality of transimpedance amplifiers (TIAs). The receiver receives a modulated optical signal utilizing the grating coupler, splits the received signal into a plurality of optical signals, generates a plurality of electrical signals from the plurality of optical signals utilizing the plurality of photodiodes, communicates the plurality of electrical signals to the plurality of TIAs, amplifies the plurality of electrical signals utilizing the plurality of TIAs, and generates an output electrical signal from coupled outputs of the plurality of TIAs. Each TIA may be configured to amplify signals in a different frequency range. One of the plurality of electrical signals may be DC coupled to a low frequency TIA of the plurality of TIAs.

Abstract: Embodiments of the present disclosure disclose a coherent receiver, including: a frequency offset estimation unit and a frequency offset compensation unit, where the frequency offset estimation unit is configured to receive signal light and local oscillator light, where the signal light is received by a first photoelectric detector, and a first intensity value is obtained, the signal light is received by a second photoelectric detector, and a second intensity value is obtained, the local oscillator light is received by a third photoelectric detector, and a third intensity value is obtained, and the local oscillator light is received by a fourth photoelectric detector, and a fourth intensity value is obtained; and the frequency offset compensation unit is configured to obtain a frequency offset value between the signal light and the local oscillator light according to a difference between a first ratio and a second ratio.

Abstract: An optical module is disclosed. According to one implementation, the optical module comprises an optical receiver, a diode, a first resistor, a first capacitor, a comparator, and a control chip. The diode anode connects electrically with a triggering signal output end of the optical receiving module, the cathode of the diode connects with one end of the first capacitor and one input end of the comparator. Another end of the first capacitor connects with the ground; the first resistor is connected in parallel with both ends of the first capacitor. A pre-set reference voltage is connected with another input end of the comparator. The optical receiver generates a first triggering signal in response to a burst mode optical signal. After inputting the first triggering signal into the diode anode, the comparator outputs a second triggering signal from the output end, triggering the control chip to generate a reset signal input into the optical receiver.

Abstract: A module for a hybrid fiber coax network includes a quad-output amplifier module that can include a port to couple to upstream devices, four ports to couple to downstream devices, and a configured port. The configured port can optionally couple to one of a radio frequency (RF) pre-amplifier or one or more optical transmitter modules or receiver modules. The module is initially provided in a default configuration as an optical node module. However, it can be pre-configured as a RF amplifier. When the configured port is coupled to the one or more optical transmitter modules or receiver modules in the default configuration, the module is operable as an optical node module. When the configured port is coupled to the RF pre-amplifier, the module is transformed to be operable as an RF amplifier.

Abstract: When necessary process times in a reception apparatus for a determination on a change area, a determination on the color of the change area, and a decoding of bit data stream exceed a predetermined time from a frame acquiring timing, and a process delay would occur, an image generator acquires a frame. In addition, a decoder temporarily stores the frame in a memory, and thereafter at a predetermined timing performs the determination on the change area, the determination on the color of the change area, and the decoding of the bit data stream.

Abstract: An heterodyne apparatus and method for measuring performance parameters of a coherent optical receiver at RF frequencies is disclosed. Two coherent lights are launched into signal and LO ports of the receiver with an optical frequency offset f. One of the lights is modulated in amplitude at two phase-locked modulation frequencies F1 and F2. COR performance parameters are determined by comparing two frequency components of the COR output. The group delay variation (GDV) information is obtained by comparing phases of two time-domain traces corresponding to frequency components of the COR output signal at the two modulation frequencies shifted by the optical frequency offset f.

Abstract: In an embodiment, method of controlling an illumination device by an output signal of a DC-DC converter is disclosed. The output signal is controlled by a PWM signal. The method includes receiving a feedback signal corresponding to variation in the output signal with respect to a pre-determined output signal, and determining a target duty cycle of the PWM signal based on the feedback signal. The PWM signal of the target duty cycle is capable of enabling the DC-DC converter to generate the pre-determined output signal. The method includes providing the PWM signal of an effective duty cycle equal to the target duty cycle over N switching pulses of the PWM signal to the DC-DC converter. The method provides the PWM signal by providing M switching pulses of a first PWM signal of a first duty cycle, and N?M switching pulses of a second PWM signal of a second duty cycle.

Abstract: An optical receiver includes an equalizer to generate a plurality of equalization coefficients corresponding to a plurality of frequencies of an optical signal received by the optical receiver. The equalizer zeroes out a first subset of the equalization coefficients corresponding to a first subset of the plurality of frequency components and applies a second subset of non-zero equalization coefficients to the first signal. The optical receiver may also include a chromatic dispersion compensator to generate inverse chromatic dispersion coefficients corresponding to the plurality of frequency components, and to zero out a first subset of the inverse chromatic dispersion coefficients corresponding to the first subset of the plurality of frequency components and further to apply a second subset of non-zero inverse chromatic dispersion coefficients to a second optical signal.

Abstract: Disclosed herein are methods, structures, and devices that provide multi-range frequency domain compensation of chromatic dispersion within optical transmission systems that offer significant operational power savings. More specifically, a method of operating frequency domain filtering structures and circuits including FFT, frequency-domain filter multiplication and iFFT functions at a lower duty cycle for shorter overlap such that significant power savings is realized.

Abstract: A method and a system for pilot-aided feedforward data recovery are provided. The method and system include a receiver including a strong local oscillator operating in a free running mode independent of a signal light source. The phase relation between the signal light source and the local oscillator source is determined based on quadrature measurements on pilot pulses from the signal light source. Using the above phase relation, information encoded in an incoming signal can be recovered, optionally for use in communication with classical coherent communication protocols and quantum communication protocols.

Abstract: In a coherent optical receiver, a received signal and an oscillator-generated signal, having frequency difference such that the receiver operates under intradyne conditions, are made to beat in a 3×3 optical coupler. A polarizing beam-splitter splits one of the signals into components with orthogonal polarization which are applied to inputs of the coupler, which receives the other of the received or oscillator-generated signal. After photoelectric conversion, the signals are fed to analog processing devices generating an electrical signal representing the received signal that is fed to a low pass filter before being demodulated. The frequency difference between the signals and the passband of the filter are such that a component of the electrical signal, oscillating at a frequency depending on the frequency difference and having amplitude and phase depending on the instant state of polarization of the received signal, is suppressed. A method is also provided.

Abstract: An apparatus includes a decision feedback equalizer configured to receive a parallel signal generated based on a first clock. The decision feedback equalizer includes a first equalization block configured to receive a first symbol of a first set of parallel symbols provided by the parallel signal during a first clock cycle of the first clock. A decision feedback equalization is performed by the first equalization block to the first symbol to provide a first decision to a second equalization block. The second equalization block is configured to receive a second symbol of the first set of parallel symbols and perform a decision feedback equalization to the second symbol using the first decision received from the first equalization block to provide a second decision during the first clock cycle.

Abstract: A utility meter device (1002) including a communications receiver (110) for receiving file fragments for the device, a processing means (150), eg microprocessor, microcontroller, and programmable non-volatile memory means (120), eg flash, EEPROM, for building and storing application and date files from the fragments, and executing a meter application of the device by processing at least one application file and associated data identified by configuration instructions in at least one of the fragments to provide data for reconfiguring a meter through a control interface (1016).

Abstract: A communication device is included in a daisy chain connection. A receiver receives a first signal from a preceding device in the daisy chain connection. A transmitter transmits the first signal received in the receiver to a succeeding device in the daisy chain connection. An acceptor accepts a second signal starting from the communication device. The transmitter transmits the second signal accepted in the acceptor to the succeeding device at a transmission rate higher than a transmission rate of the first signal received in the receiver.

Abstract: An analog-to-digital converting system includes at least one first main analog-to-digital converting unit, at least one second main analog-to-digital converting unit, at least one auxiliary analog-to-digital converting unit, and a calibration unit. Each first main analog-to-digital converting unit is located on a first channel. The first channel includes sample period. Each first main analog-to-digital converting unit receives a first sampling value. Each first sampling value includes a first sample clock. An analog-to-digital converting method calibrates timing-skew of the analog-to-digital converters by delaying a time difference on the sampling value.

Abstract: An optical receiver comprises an optical port configured to receive an encoded optical signal, and a demodulation block indirectly coupled to the port and comprising a multiplexer, wherein the multiplexer is configured to receive an encoded electrical signal, wherein the encoded electrical signal is associated with the encoded optical signal, and wherein the encoded electrical signal is encoded using a code division multiple access (CDMA) scheme, receive a code associated with the scheme, perform a dot multiplication of the encoded electrical signal and the code, and generate a differential voltage based on the dot multiplication.

Abstract: The laser driver including a difference amplifier, a target potential circuit, an adjusting circuit, and bypass circuit is disclosed. The differential amplifier outputs a driving signal and a reverse driving signal having a phase opposite to a phase of the driving signal. The bypass circuit outputs an output current in response to the driving signal for generating a driving current for a semiconductor laser element that emits an optical signal in response to the driving signal. The adjusting circuit controls average potential of the driving signal and the reverse driving signal, so that the average potential becomes substantially equal to a target potential provided by the target potential circuit. The target potential corresponds to average optical power of the optical signal. When amplitude of the driving signal is changed for adjusting an extinction ratio of the optical signal, the adjusting circuit maintains the average optical power in a constant value.

Abstract: An optical transmitter transmits a dual polarization optical Nyquist frequency domain multiplexed signal. The signal includes a first polarization component and a second polarization component. Each component comprises multiple subchannels, possibly having different subchannel bandwidths and different modulation schemes. An optical receiver receives the signal and recovers transmitted data.

Abstract: To enable signal position detection, frequency offset compensation, clock offset compensation, and chromatic dispersion amount estimation in a communication system based on coherent detection using an optical signal, even on a signal having a great offset in an arrival time depending on a frequency due to chromatic dispersion. An optical signal transmitting apparatus generates specific frequency band signals having power concentrated on two or more specific frequencies and transmits a signal including the specific frequency band signals. An optical signal receiving apparatus converts a received signal into a digital signal, detects positions of the specific frequency band signals from the converted digital signal, estimates frequency positions of the detected specific frequency band signals, and detects a frequency offset between an optical signal receiving apparatus and an optical signal transmitting apparatus.

Abstract: In one embodiment, a method for receiving optical signals includes receiving a first set of one or more signals and a second set of one or more signals, determining a block length used to process the first set of signals, and processing the first set of signals using the block length. The first set of signals and the second set of signals are separated by a guard band. The block length is based upon the width of the guard band.

Abstract: Provided is a light-emitting diode driving apparatus, including: a switching transistor which becomes an on-state or an off-state in response to a pulse width modulation signal; a light-emitting diode electrically connected with a second terminal of the switching transistor; a first comparison circuit which outputs a first voltage depending on a comparison result between a first input voltage corresponding to a voltage applied to the light-emitting diode and a first threshold voltage; a second comparison circuit which outputs a second voltage depending on a comparison result between a second input voltage corresponding to a voltage applied to the light-emitting diode and a second threshold voltage; and a signal processing circuit which detects a failure in the light-emitting diode on the basis of an output state of the pulse width modulation signal, the first voltage, the second voltage and a third voltage on the second terminal side of the switching transistor.

Abstract: The invention inter alia relates to a method of receiving an optical-duo-binary, ODB, signal (S), which has a predefined ODB-transmission bit-rate (B), using a photoreceiver, said method comprising the step of filtering the ODB signal using a filter (10) which provides a frequency peak in the photoreceiver's frequency response located in the spectral range between 30% and 70% of the predefined ODB-transmission bit-rate.

Abstract: An optical communication system includes an optical transmitter, and an optical receiver connected via a transmission line to the optical transmitter, in which system the optical transmitter transmits a continuous-wave light signal that enables beat detection when combined with a local oscillator signal in the optical receiver, and the optical receiver acquires a beat waveform through digital sampling by detecting the light signal using the local oscillator signal, performs frequency analysis on digitally sampled data having the beat waveform prior to demodulation, and controls the local oscillator frequency based upon the beat frequency.

Abstract: A receiver includes an interface for translating an optical signal into two differential electrical signals for a first amplifier. The first amplifier modifies the two differential electrical signals to produce a first signal that is the amplitude of difference between the two differential electrical signals, which contains the information from the optical signal. A variable gain track and hold amplifier (VGTHA) receives the first signal and a clock signal and provides a conditioned analog signal for digital processing. A clock source provides the clock signal, which is aligned with the peak amplitude of the first signal.

Abstract: A method of detecting a signal in an optical receiver is described. The method includes converting a received optical signal to a digital electrical signal comprising a plurality of samples, applying a predetermined phase rotation to said samples to obtain amplitude and phase components of phase range adjusted sample values, and performing a first detection process based on the amplitude and phase components of the phase range adjusted sample values.

Abstract: An optical transceiver converts a received optical signal to an electric signal and converts the electric signal to a digital signal, and has an adaptive equalizer to adaptively equalize the digital signal, a synchronization part to synchronize a first polarized wave and a second polarized wave contained in the adaptively equalized digital signal and having polarization axes perpendicular to each other, and a symbol offset determination part to determine an amount of symbol offset between the first polarized wave and the second polarized wave based upon symbol synchronization information of the first polarized wave and the second polarized wave supplied from the synchronization part, the symbol offset determination part being configured to repeat determination of the amount of symbol offset and restart the adaptive equalizer until the symbol offset is minimized.

Abstract: A source-synchronous communication system in which a first integrated circuit (IC) conveys a data signal and concomitant strobe signal to a second IC. One or both ICs support hysteresis for the strobe channel that allows the second IC to distinguish between strobe preambles and noise, and thus prevent the false triggering of data capture. Hysteresis may also be employed to quickly settle the strobe channel to an inactive level after receipt of a strobe postamble.

Abstract: An optical receiver includes a feedback circuit that applies a feedback signal to a front-end circuit prior to the front-end circuit converting an optical signal into an analog electrical signal. In particular, the optical receiver includes a digital slicer that determines a digital electrical signal from the analog electrical signal based on a reference voltage that specifies a decision threshold and a clock that specifies sampling times. The feedback circuit determines the feedback signal at least one previous bit preceding a current bit in the analog electrical signal that is provided by the digital slicer and an impulse response of a communication channel. Moreover, the feedback signal has a pulse width that is less than a bit time of the clock. In this way, the optical receiver can cancel post-cursors of the current bit, even when the communication channel includes a low-pass filter.

Abstract: The present technique relates to a demodulation device, a demodulation method and a program capable of realizing a demodulation process at a rate equivalent to a case where I and Q channel signals are not inverted, even when the I and Q channel signals are inverted. A frequency correction unit establishes synchronization of a frequency and clock based on a signal from a frequency synchronization unit. A channel inversion detection unit of a frame synchronization unit detects presence or absence of inversion of I and Q channel signals, and supplies, as a detection result, a channel inversion detection result to the channel inversion control unit. The channel inversion control unit switches the I and Q channel signals if the inversion has occurred, based on the channel inversion detection result. This technique can be applied to a demodulation device.