55 results about "Spectral inversion" patented technology

An apparatus of processing a time domain synchronous orthogonal frequency-division-multiplexing (TDS-OFDM) signal is provided. The apparatus includes a receiving block and a demodulating block. The receiving block receives the TDS-OFDM signal, and generates a down-converted signal according to the received TDS-OFDM signal. The demodulating block is coupled to the receiving block, and demodulates the down-converted signal to generate a transport stream. The demodulating block has a transmission parameter signaling (TPS) decoder implemented for performing a TPS decoding operation to generate a TPS decoding result and verifying a spectrum direction of the received TDS-OFDM signal according to the TPS decoding result.

The invention discloses a method and device for rapidly measuring sidewall appearance of a micro-nano deep groove structure, which can simultaneously and rapidly measure the parameters of the sidewall appearance of the micro-nano deep groove structure, such as line width, groove depth, sidewall angle, sidewall roughness and the like. The method comprises the steps of: projecting elliptical polarized lights, which is obtained by polarizing light beams with the wavelengths ranging from near infrared waveband to middle infrared waveband, onto the surface of a structure to be measured; collecting zero-level diffraction signals on the surface of the structure to be measured, and calculating to obtain a measured infrared spectroscopic ellipsometry of the micro-nano deep groove structure; calculating theoretical spectroscopic ellipsometries in the near infrared waveband and the middle infrared waveband respectively by using a wavelength allocation modeling method, matching the theoretical spectroscopic ellipsometries with the infrared spectroscopic ellipsometry measured in the experiment by using a stepwise spectral inversion method, and sequentially extracting the groove structure parameter and the roughness parameter. The device comprises an infrared light source, first, second, third and fourth off-axis parabolic mirrors, a Michelson's interferometer, a planar reflector, a polarizer, a sample bench, an analyzer, a detector and a computer; and the method is a noncontact, nondestructive low-cost method for rapidly measuring the sidewall appearance.

The invention relates to SI (Spectrum Inversion)-based nonlinear fiber damage compensation method and device in an O-OFDM (Optical-Orthogonal Frequency Division Multiplexing) system, belonging to the field of optical communication and applied to the O-OFDM system for nonlinear fiber damage compensation. The whole compensation module is arranged in front of a receiver of the O-OFDM system and comprises an SI unit and an HNLF (Highly Non-Linear Fiber) which has a certain length and is arranged behind the SI unit, wherein SI is realized by an SOA (Semiconductor Optical Amplifier) based on FWM (Four Wave Mixing) effect.

The invention provides methods and apparatuses to detect spectrum inversion based on estimated frequency offset in carrier signal. In one embodiment, a receiver includes an I/Q swap module to output an in-phase component and a quadrature-phase component; a frequency offset estimator to determine an offset in carry frequency of the in-phase and quadrature-phase components; and a spectrum inversiondetector coupled to the frequency offset estimator and the I/Q swap module. The spectrum inversion detector is configured to signal the I/Q swap module to swap the in-phase component and the quadrature-phase component when an absolute value of the offset in carry frequency is above a predetermined threshold.

Disclosed herein is a modulator (50) for polarization-division multiplexing (PDM) transmission. The modulator (50) comprises first and second DP-MZMs (12, 28) associated with first and second polarizations, each DP-MZM (12, 28) having an input for an in-phase and a quadrature driving signal for modulating the in-phase and quadrature components of an optical signal according to respective transfer functions, and a detector (58) suitable for detecting light comprising at least a portion of the light outputted by the first DP-MZM (12) and a portion of the light outputted by the second DP-MZM (28). The modulator (50) is adapted to superimpose a first pilot signal on one of the in-phase and quadrature driving signals of the first DP-MZM (12) and on one of the in-phase and quadrature driving signals of the second DP-MZM (28), and a second pilot signal on the respective other of the in-phase and quadrature driving signals of the first and second DP-MZMs (12, 28). Further, the first and second pilot signals are chosen such that the signal detected by said detector (58) is indicative as to whether the slopes of the transfer functions are different for the in-phase and quadrature components of one of the first and second DP-MZMs (12, 28) and identical for the other of the first and second DP-MZMs (12, 28).

Disclosed herein is a reception apparatus including: a spectrum inversion detection section configured to detect the occurrence or absence of spectrum inversion in a received signal complying with the Digital Video Broadcasting-Terrestrial 2 standard known as DVB-T2, using a P1 signal constituting the received signal; a spectrum inversion section configured to perform a spectrum inversion process on the received signal if the occurrence of the spectrum inversion is detected at least by the spectrum inversion detection section; and a demodulation section configured to demodulate the received signal having undergone the spectrum inversion process if the occurrence of the spectrum inversion is detected by the spectrum inversion detection section, the demodulation section further demodulating the received signal yet to undergo the spectrum inversion process if the absence of the spectrum inversion is detected by the spectrum inversion detection section.

An optical filter apparatus transmits less than 5% of light within a notch spectral range about a central line wavelength with a notch bandwidth, and transmits more than 90% of light within a transmission spectral range that extends over an adjacent pass band of longer and shorter wavelengths and excludes the notch. The apparatus has a first thin film interference filter and a second thin film interference filter in the path of incident light reflected from the first filter. The first and second thin film interference filters are each treated to transmit light of the notch spectral range and reflect light of the transmission spectral range and each have thin film layers formed on a substrate, including first layers having a first refractive index, and second layers having a higher second refractive index. The notch bandwidth at full width half transmission is less than 5% of the central line wavelength.

A system analyzer may generate an estimated frequency response of a device, system, communication medium, or combination thereof by utilizing a stimulus signal that is robust against IQ modulator impairments. A stimulus generator may be used to generate a plurality of discrete tones according to a frequency spacing and a frequency offset. The frequency spacing and the frequency offset cause spectrally inverted spurs (generated by impairments of the IQ modulator) to occur at frequencies other than frequencies of said modulated signal that are associated with said plurality of discrete tones. Additionally, by implementing a Discrete Fourier Transform (DFT) to possess a frequency resolution equal to the frequency offset, there is no leakage of power associated with the spectrally inverted spurs into frequency bins of the DFT associated with the desired frequency components. Likewise, leakage between the desired frequency components and leakage associated with the local oscillator may be avoided.

The invention relates to a real-time, convenient and reliable method for field rapid detection on the content of nitrogen and phosphorus substances in eutrophic water, and a low-cost field detection device mounted in an ocean wireless measurement and control network or an aquaculture Internet of Things. A simulation study on spectral inversion of the content of nitrogen and phosphorus substances in water is carried out, and the effect of spectral signals on chromatic aberration is fused effectively. On the basis, a relatively complete sample set of spectral characteristic information of eutrophication characterization parameters, such as soluble organic matters, chemical oxygen demand, total nitrogen and total phosphorus, is established as a reference image library; the reference image library contains prominent features, such as gray levels, image borders, outlines, surfaces and spectral lines. Finally, obtained images (including spectral information images) are compared with the reference image library and analyzed, sequentially, chromatic aberration of water eutrophication can be inversed and simulated, and the total content of nitrogen and phosphorus substances can be deduced.

Methods and systems may mitigate nonlinear noise (NLN) penalties for optical paths using spectral inversion in optical transport networks. Using a tunable dispersion compensator with an optical amplifier at each span in an optical path, the dispersion along the optical path may be modified to a normalized dispersion for each span. In this manner, the dispersion associated with NLN accumulation may be balanced by NLN compensation to reduce overall NLN levels for the optical path.

The invention relates to a phase screen modeling method for discrete raindrop media based on a spectral inversion method, and belongs to discrete raindrop medium phase screen modeling field. In order to overcome the shortcomings that the description of light field information is incomplete in a phase screen model of discrete raindrop media, the requirements of a virtual test is not satisfied, and the phase disturbance of raindrops to the light field is not considered, the invention proposes a phase screen modeling method for discrete raindrop media based on the spectral inversion method, the phase screen modeling method including the steps of obtaining scattering potential energy of raindrop particles; obtaining the scattering potential energy after Fourier transform; obtaining an approximate value of the scattering potential energy through the scattering potential energy after Fourier transform; expressing a second-order correlation moment three-dimensional power spectral function of a dielectric constant of the raindrop particles by a formula; expressing a dielectric constant power spectrum of the raindrops by a formula; expressing a second-order correlation moment power spectrum of a medium refractive index of the raindrops by a formula; and obtaining a phase screen model of mixed media on a transmission path according to the spectral inversion method. The invention is applicable to a simulation model of laser transmission in rain.

A WDM system includes a transmission station, a receiving station, a first optical path and a second optical path. The first optical path includes a first section and a second section, the second section being capable of compensating at least partially the dispersion accumulated by a series of optical channels along the first section. The series of channels includes at least a first plurality of channels having an average dispersion of the same sign in the first optical path. The system also includes at least a first conversion device, capable of inverting the spectrum and modifying the wavelength of at least the first plurality of channels, to produce a second plurality of channels having an average chromatic dispersion of the same sign in the second optical path.

The invention discloses a method for restoring interference pattern data spectra based on wavelet analysis. The method comprises the steps of applying the fitting interpolation method based on the wavelet analysis to non-uniform sampling interference pattern reconstruction, and conducting spectral inversion; firstly applying the fitting method based on the wavelet analysis to conduct fitting on non-uniform sampling interference data to obtain a fitted interference data curve, and then conducting uniform interpolation sampling to obtain uniformly-sampled interference data; conducting the FFT on the uniformly-sampled interference data on the basis of the interference spectroscopy theory to obtain a resorted spectral pattern. According to the result of a simulation experiment, it can be seen that the method is more suitable for the characteristics that the interference data change severely at the positions with zero optical path difference and change slowly at the positions with larger optical path differences, and the interference data curve is better fitted. After the uniform sampling, the FFT is carried out to obtain the spectral inversion pattern. The method has the advantages of being capable of exquisitely fitting the interference pattern data, better reflecting the characteristics of the interference pattern data and being lower in fitting error.

The invention discloses a method for eliminating spectrum inversion. The method comprises the following steps of: detecting whether a received signal has a spectrum inversion problem or not; if the received signal has the spectrum inversion problem, checking whether a frequency point index value FFT_IDX of fast Fourier transform is 0 or not; if the frequency point index value FFT_IDX is 0, adopting an orthogonal inphase frequency domain signal of the 0th sub-carrier of the received signal as an inphase orthogonal frequency domain signal of the 0th sub-carrier of an output signal; and if the frequency point index value FFT_IDX is not 0, adopting the orthogonal inphase frequency domain signal of the (N-FFT_IDX)th sub-carrier of the received signal as the inphase orthogonal frequency domain signal of the (N-FFT_IDX)th sub-carrier of the output signal, wherein N is the number of sampling points of the fast Fourier transformer, and the frequency point index value FFT_IDX is an integer ranged from 0 to N-1.

A process of correction of the spectral inversion for a receiver in a digital communication system: the process allows the reception in the receiver of a training sequence presumably known according to a modulation of type π/2 BPSK or MDP2. The process includes the following steps: Demodulating of the training sequence; Calculating of the differential correlation on a set of N received samples (R_n) and presumably sent (S_n) to generate a result; Using the result to detect the beginning of the frame and to order a spectral inversion in the chain of reception of the aforementioned receiver before launching the detection of the beginning of the frame. A receiver to process automatically the spectral inversion is also described.

The invention discloses a gas detection method based on hyperspectral infrared image processing. The gas detection method based on the hyperspectral infrared image processing comprises the following steps of (a), collecting the infrared spectral data of a target area by adopting a hyperspectral infrared imaging system; (b), reducing the noise of the infrared spectral data and image noise of each wave band by utilizing a nonlinear wave filter; (c), calculating the infrared absorption spectral curve of a gas by adopting a gas spectral inversion algorithm; (d), carrying out normalization on the spectral data processed in step (b) and special data obtained through calculation in step (c), so as to reduce the influence of a direct component in a spectral line, and afterwards, judging the type and the concentration of the gas by adopting a feature weighting based generalized angular similarity measuring method. According to the gas detection method based on the hyperspectral infrared image processing, the noise of the infrared spectral data and the image noise of each wave band are reduced by utilizing the nonlinear wave filter; afterwards, the noise reduction, the dimensionality reduction and the spectral inversion operation are carried out on a collected hyperspectral image; the processed hyperspectral image is compared with data in a gas infrared absorption spectrum library; thus, the type of the gas can be identified and the concentration of the gas can be estimated.

The invention provides a frequency spectrum inversion judging device which comprises a differential motion correlator and a judging module. The differential motion correlator is used for applying odd-order differential motion correlation operation on an input signal and a known signal so as to generate a differential motion relevant result. When the input signal is judged as a target signal corresponding to the known signal, the judging module judges whether frequency spectrum inversion exists in the input signal according to the phase of the differential motion relevant result.

The invention belongs to the technical field of geological exploration, and particularly relates to a mineral content spectral inversion method based on a deep neural network. According to the mechanism and inversion characteristics of the rock mineral spectrum, a neural network model capable of rapidly and accurately inverting the mineral content of the surface rock soil is established, and the mineral content of the surface rock soil can be determined, analyzed and evaluated by using hyperspectral data.

Methods and systems are provided for wavelength shift elimination during spectral inversion in optical networks. The method includes receiving an input optical signal, and generating a combined optical signal by combining, by Bragg scattering, the input optical signal having an input wavelength with a first pump signal having a first wavelength. The method further includes converting the combined optical signal into an output optical signal, by phase-conjugation, using a second pump signal having a second wavelength. The output optical signal has the same wavelength as the input optical signal.