Abstract: A method and an apparatus for evaluating transmission impairments of a multiplexing converter. According to the method, impairments of a multiplexing converter are equivalent to the equivalent multiplicative noise and the equivalent additive noise, so as to allow evaluation of transmission impairments of the multiplexing converter, thereby to allow evaluation of the performance of a communication system. The multiplexing converter is a multiplexing analog-to-digital converter, or a multiplexing digital-to-analog converter. According to the present application, impairments of a multiplexing converter can be evaluated accurately, the performance evaluation of a communication system using the multiplexing converter is given, without being affected by an amplitude, a modulation format and a transmission rate of an input signal.

Abstract: A method, an apparatus and a system to measure nonlinear correlation parameters of a nonlinear device, a processor to, perform band-stop filtering on a signal to be measured to generate a notch signal, and calculate a first nonlinear correlation parameter of the nonlinear device when the signal to be measured is transmitted according to a first output signal of the nonlinear device after the notch signal is input into the nonlinear device; calculate gain compression correction coefficients according to a second output signal of the nonlinear device after the first input signal is input into the nonlinear. The first input signal and the signal to be measured may have identical power and different signal probability distribution. The processor is to correct the first nonlinear correlation parameter according to the gain compression correction coefficients to obtain a second nonlinear correlation parameter of the nonlinear device when the signal to be measured is transmitted.

Abstract: An apparatus and a method for monitoring an analog characteristic of an optical transmitter may include inputting a first signal to a first electro-optical converter to obtain a optical signal to-be-measured; inputting a second signal to a second electro-optical converter to obtain a modulated local signal, so that the second signal is determined according to the first signal and a to-be-monitored analog characteristic of the first electro-optical converter; performing correlation processing on the optical signal to-be-measured and the modulated local signal to obtain at least one correlation quantity; and estimating an analog characteristic of the first electro-optical converter according to the correlation quantity.

Abstract: An apparatus and a method for determining an optical phase difference of a sub-signal of an optical transmitter. The method including: inputting a first input signal to a first electro-optical conversion unit, to enable the first electro-optical conversion unit to modulate to-be-modulated light according to the first input signal to obtain a first output signal; inputting a second input signal to a second electro-optical conversion unit, to enable the second electro-optical conversion unit to modulate to-be-modulated light according to the second input signal to obtain a second output signal; where correlation of the second input signal and the first input signal is not 0. The method includes performing a coherent detection operation based on the first output signal and the second output signal to obtain a first output quantity and a second output quantity; and determining an optical phase difference.

Abstract: An apparatus and a method for determining signal correlation, the method including: inputting a first signal to a first electro-optical conversion unit, to enable the first electro-optical conversion unit to modulate to-be-modulated light according to the input first signal and to obtain a to-be-measured signal; inputting a second signal to a second electro-optical conversion unit, to enable the second electro-optical conversion unit to modulate to-be-modulated light according to the input second signal and to obtain a correlation signal; determining a product signal of the to-be-measured signal and the correlation signal via a photoelectric method or an optical method; and determining correlation of the to-be-measured signal and the correlation signal by performing an electrical average operation on the product signal. Therefore, correlation of two high-speed signals is obtained by only using a low-bandwidth electrical device without requiring use of a large-bandwidth multiplier.

Abstract: An apparatus and a method for real-time monitoring delay skew of a sub-signal of an optical transmitter may include inputting a first input signal to a first electro-optical conversion unit, modulating to-be-modulated light to obtain a first output signal; inputting a second input signal to a second electro-optical conversion unit, modulating to-be-modulated light to obtain a second output signal, the second input signal is a differential signal of the first input signal; performing correlation operation processing on the first output signal and the second output signal to obtain correlation of the first input signal and the second input signal; and determining delay skew between an output signal of the first electro-optical conversion unit and an output signal of the second electro-optical conversion unit according to the correlation and a pre-set corresponding relation between a correlation and the delay skew.

Abstract: A method and an apparatus for evaluating transmission impairments of a multiplexing converter. According to the method, impairments of a multiplexing converter are equivalent to the equivalent multiplicative noise and the equivalent additive noise, so as to allow evaluation of transmission impairments of the multiplexing converter, thereby to allow evaluation of the performance of a communication system. The multiplexing converter is a multiplexing analog-to-digital converter, or a multiplexing digital-to-analog converter. According to the present application, impairments of a multiplexing converter can be evaluated accurately, the performance evaluation of a communication system using the multiplexing converter is given, without being affected by an amplitude, a modulation format and a transmission rate of an input signal.

Abstract: The present disclosure provides an apparatus and method for measuring a nonlinear signal-to-noise ratio, and a test instrument. The method for measuring a nonlinear signal-to-noise ratio may include performing notch operation on at least one frequency point in a spectrum of an input signal in a symbol domain or a bit domain; performing spectrum measurement on an output signal after passing through a nonlinear system; and estimating a nonlinear signal-to-noise ratio of at least one frequency point of the nonlinear system according to a spectrum of the output signal. According to the embodiments of the present disclosure, when the notch operation is performed, internal structures of symbols or bits of the input signal may be retained, and an accuracy of the measurement of the nonlinear signal-to-noise ratio may be improved.

Abstract: A method, an apparatus and a system to measure nonlinear correlation parameters of a nonlinear device, a processor to, perform band-stop filtering on a signal to be measured to generate a notch signal, and calculate a first nonlinear correlation parameter of the nonlinear device when the signal to be measured is transmitted according to a first output signal of the nonlinear device after the notch signal is input into the nonlinear device; calculate gain compression correction coefficients according to a second output signal of the nonlinear device after the first input signal is input into the nonlinear. The first input signal and the signal to be measured may have identical power and different signal probability distribution. The processor is to correct the first nonlinear correlation parameter according to the gain compression correction coefficients to obtain a second nonlinear correlation parameter of the nonlinear device when the signal to be measured is transmitted.

Abstract: A performance estimation apparatus and method for a nonlinear communication system and an electronic device. The nonlinear communication system is equated with by an equivalent model including an equivalent linear model and an equivalent additive noise model, and the equivalent additive noise outputted by the equivalent additive noise model is mathematically uncorrelated to the signal inputted into the equivalent model. Performances of the nonlinear communication system of different modulation formats at different baud rates may be accurately estimated.

Abstract: The present disclosure provides an apparatus and method for measuring a nonlinear signal-to-noise ratio, and a test instrument. The method for measuring a nonlinear signal-to-noise ratio may include performing notch operation on at least one frequency point in a spectrum of an input signal in a symbol domain or a bit domain; performing spectrum measurement on an output signal after passing through a nonlinear system; and estimating a nonlinear signal-to-noise ratio of at least one frequency point of the nonlinear system according to a spectrum of the output signal. According to the embodiments of the present disclosure, when the notch operation is performed, internal structures of symbols or bits of the input signal may be retained, and an accuracy of the measurement of the nonlinear signal-to-noise ratio may be improved.

Abstract: A method and apparatus for generating a signal. The method includes: by taking a reference signal as a standard, cyclically performing isoprobabilistic processing and isospectral processing, or cyclically perform isoprobabilistic processing, perturbation processing and isospectral processing, on an input signal, until an obtained signal satisfies both a requirement on a target probability distribution and a requirement on a target spectrum, where a probability distribution of the reference signal satisfying the requirement on a target probability distribution, the isoprobabilistic processing referring to processing that makes the probability distribution of an output signal identical to the probability distribution of the reference signal. Therefore, a signal that satisfies both the requirement on the specific probability distribution and the requirement on the spectrum can be generated, and the degree of compliance is higher.

Abstract: This disclosure provides a signal generation device and an equalization processing device. The signal generation device generates a pilot sequence and payload, the pilot sequence and the payload having identical or similar amplitude probability characteristics. Hence, nonlinear interference may be resisted, and performance of the communication system may be improved.

Abstract: A performance estimation apparatus and method for a nonlinear communication system and an electronic device. The nonlinear communication system is equated with by an equivalent model including an equivalent linear model and an equivalent additive noise model, and the equivalent additive noise outputted by the equivalent additive noise model is mathematically uncorrelated to the signal inputted into the equivalent model. Performances of the nonlinear communication system of different modulation formats at different baud rates may be accurately estimated.

Abstract: A method and apparatus for monitoring the change of state of polarization and a receiver. The method for monitoring the change of state of polarization includes: extracting a matrix of equalization filter tap coefficients of a receiver; performing an FFT operation of N taps on each path of equalization filter tap coefficients of the matrix to obtain a converted matrix, a sum of each path of equalization filter tap coefficients of the converted matrix being a value of non-zero frequency; and estimating an amount of change of state of polarization by using at least one path of equalization filter tap coefficients of the converted matrix. Thus, as the sum of the tap coefficients is shifted in the frequency domain from the zero frequency to a higher frequency (non-zero frequency), an effect of imperfection of the transmitter on a monitoring result of the change of state of polarization may be avoided.

Abstract: An inter-channel linear crosstalk estimation method and apparatus and a communication system are disclosed.

Abstract: A method and apparatus for monitoring the change of state of polarization and a receiver. The method for monitoring the change of state of polarization includes: extracting a matrix of equalization filter tap coefficients of a receiver; performing an FFT operation of N taps on each path of equalization filter tap coefficients of the matrix to obtain a converted matrix, a sum of each path of equalization filter tap coefficients of the converted matrix being a value of non-zero frequency; and estimating an amount of change of state of polarization by using at least one path of equalization filter tap coefficients of the converted matrix. Thus, as the sum of the tap coefficients is shifted in the frequency domain from the zero frequency to a higher frequency (non-zero frequency), an effect of imperfection of the transmitter on a monitoring result of the change of state of polarization may be avoided.

Abstract: Embodiment of the present disclosure provide an apparatus and method to monitor a change of a polarization state resulted from an optical link and an optical receiver, in which by obtaining a change matrix of response matrices at two moments, and determining a parameter characterizing a change of a polarization state resulted from an optical link according to feature values of a change matrix in a Stokes space corresponding to the response matrices. The change of the polarization state resulted from the optical link is dynamically monitored in a real-time manner, independent of a polarization state of an input signal of the optical link, and no extra hardware and control may be needed.

Abstract: Embodiments of this disclosure provide a phase noise compensation apparatus and method and a receiver, in which modified signals are determined according to estimated values of an imperfection parameter of a transmitter and training sequence signals in transmission signals, and phase noises of the received signals are determined according to the modified signals, hence, an effect of the imperfection parameter of the transmitter on the phase noise is taken into account, and the phase noise may be accurately estimated, thereby performing compensation on the phase noise, and ensuring a transmission efficiency and performance of the system.

Abstract: Embodiment of the present disclosure provide an apparatus and method to monitor a change of a polarization state resulted from an optical link and an optical receiver, in which by obtaining a change matrix of response matrices at two moments, and determining a parameter characterizing a change of a polarization state resulted from an optical link according to feature values of a change matrix in a Stokes space corresponding to the response matrices. The change of the polarization state resulted from the optical link is dynamically monitored in a real-time manner, independent of a polarization state of an input signal of the optical link, and no extra hardware and control may be needed.