19results about How to "Improve demodulation accuracy" patented technology

The invention discloses an FPGA (Field Programmable Gate Array) implementation method of a DVB (Digital Video Broadcasting) high-speed demodulator. A digital signal enters a parallel DDC (Direct Digital Control) module and is re-adapted to multiple symbol rates; the parallel AGC module adjusts the power of the digital signal to a fixed power value; the method comprises the following steps: passing through Oamp; m algorithm: completing symbol synchronization; related peaks are extracted, and frame synchronization is completed; correcting the frequency to enable the frequency to reach participation frequency deviation; performing frequency compensation on the digital signal after loop filtering; after error information is calculated and filtered, the digital signal is compensated; and restoring the original information of the digital signal. According to the invention, by adopting the parallel processing module, the real-time performance and the parallelism degree of digital signal processing can be greatly improved, and the performance of the whole demodulator is enhanced. Each module is designed to be adaptive to the change of a digital signal, for example, the AGC module can dynamically adjust the power of the digital signal to ensure that the output digital signal is always kept at a fixed power level so as to adapt to different receiving conditions.

The utility model relates to a high-capacity wavelength division multiplexing fiber bragg grating sensing system in the field of fiber sensing. The high-capacity wavelength division multiplexing fiber bragg grating sensing system comprises a mode-locked fiber laser, a spectrum expansion module, a three-port optical circulator, a fiber bragg grating array, a dispersion module, a photoelectric detector, a data acquisition module and a data processing module. The spectrum expansion module is composed of an optical fiber amplifier, a nonlinear element and a polarization controller; the optical fiber amplifier is composed of an optical isolator, an erbium-doped optical fiber, a wavelength division multiplexer and a pump light source. According to the sensing system, the dispersion Fourier transform technology is applied, the offset of the center wavelength of the fiber bragg grating is mapped into the offset of time delay between time domain reflected light pulses, and the demodulation rate and precision of the fiber bragg grating sensing system are improved; and by adding a spectrum expansion module, the spectrum of pulse data output by the light source laser is expanded into a super-continuum spectrum by using a nonlinear effect, and the simultaneous measurement of hundreds of fiber bragg grating sensors can be theoretically supported.

The invention relates to the technical field of signal transmission, in particular to a wireless while-drilling pulse signal transmission system under a high-temperature condition. The system comprises a signal generation part, a signal transmission part and a signal receiving part, the signal generation part is used for sensing changes of temperature, pressure or vibration of an underground environment through a piezoelectric crystal, generating an initial electric signal, forming a mechanical signal and converting the mechanical signal into an initial pulse signal in an electric signal form again; the signal transmission part is used for performing mud pressure modulation on the initial pulse signal to obtain a phase change function; performing nonlinear correction to obtain a correction result; performing signal coding modulation based on the correction result; the modulation signal is sent to a signal receiving part at a far end; and the signal receiving part is used for receiving the modulation signal and demodulating the modulation signal to obtain a demodulated output signal. A complete, efficient and reliable solution is provided for wireless while-drilling pulse signal transmission under the high-temperature condition.

The invention discloses a high-order modulation iteration frequency offset phase correction method and device, and the method comprises the steps: carrying out the initial estimation of frequency offset and phase offset at a known position based on the known sequence or pilot frequency information, calculating the initial estimation of signal frequency offset and phase offset at a high-order modulation symbol position, and carrying out the compensation of the frequency offset and phase offset; demodulating the signal after initial correction, and extracting constellation point estimation of the high-order modulation signal; calculating estimated update values of frequency offset and phase offset through the high-order modulation signal estimated value; and correcting the received signal by using the estimated phase offset and frequency offset, and carrying out loop iteration in sequence until the preset precision or iteration times is reached. According to the iterative joint correction method and device, the frequency offset and the phase error can be gradually reduced, and the demodulation accuracy of the high-order modulation signal is improved.

The present invention belongs to the technical field of control circuits, and discloses an LVDT displacement sensor excitation generation and demodulation circuit, including a DSP control circuit, an excitation generation circuit, a frequency calibration circuit, a signal demodulation circuit, and a power supply circuit. The DSP control circuit outputs a driving signal to the excitation generation circuit, and the excitation generation circuit filters an AC signal for driving the LVDT sensor. At the same time, the AC signal is introduced into the calibration circuit to realize real-time monitoring and dynamic adjustment of the excitation signal. Finally, the electrical signal output by the LVDT displacement sensor is solved by the DSP control circuit to obtain the actual displacement value of the sensor. The present invention can flexibly and in real time change the output excitation frequency through the DSP control circuit, can adapt to the driving requirements of different LVDT displacement sensors, and can overcome the shortcomings of low precision of dedicated integrated chips by selecting high-precision configuration devices; in addition, compared with similar driving circuits, the present invention has the characteristics of strong noise suppression ability, good stability, wide application range, strong environmental adaptability, etc.

This invention discloses a multi-channel programmable miniaturized high-speed FBG demodulation system and method based on an AWG (Optical Fiber Optic Generator), belonging to the field of fiber optic sensing technology. The AWG-based multi-channel programmable miniaturized high-speed FBG demodulation system includes a high-stability broadband light source module, a low-loss isolation module, a miniaturized programmable fiber optic amplifier, a circulator, a two-stage miniaturized high-speed optical switch, a high-crosstalk AWG module, a photoelectric conversion module, a programmable A / D conversion module, and a core control module. The AWG-based multi-channel programmable miniaturized high-speed FBG demodulation method involves the optical signal entering an FBG sensor array, the FBG sensor reflecting the optical signal, the reflected optical signal entering the AWG module, and the output light undergoing photoelectric conversion to calculate the center wavelength of the FBG sensor. This invention, based on an AWG, improves demodulation accuracy while ensuring the demodulation range, achieving continuous wavelength demodulation within the AWG wavelength range.

According to the EFPI acoustic sensor demodulation system and method, three lasers provide three beams of lasers with different wavelengths, an optical fiber coupler is connected with the three lasers so as to combine the three beams of lasers with different wavelengths into one beam of light, a scanning laser carries out wavelength scanning, lasers with variable wavelengths are provided for the initial cavity length of an EFPI acoustic sensor, and the optical fiber coupler is connected with the three lasers. The optical switch is connected with the optical fiber coupler and the scanning laser, the wavelength division multiplexer receives reflected light of the EFPI acoustic sensor probe and divides the reflected light into light with three different wavelengths, the three photoelectric detectors are connected with the wavelength division multiplexer and collect light intensity signals of the light with the three different wavelengths, the computer carries out operation processing on the collected light intensity signals, and the EFPI acoustic sensor is obtained. Phase information of the interference light beams is obtained, and the real-time cavity length of the EFPI acoustic sensor is obtained through demodulation.

The invention relates to a low-resolution Brillouin frequency spectrum demodulation method based on an artificial neural network, and the method comprises the following steps: S1, adjusting the time domain and frequency domain sampling rates of a Brillouin optical time domain sensor in a model training stage, obtaining a low-resolution Brillouin frequency spectrum, and taking the low-resolution Brillouin frequency spectrum as a sample of a data training set; and meanwhile, changing an external physical quantity applying mode of the optical fiber to be measured, such as a heating or strain position and a temperature or strain amplitude, establishing quasi-continuous temperature or strain field distribution information under different parameter conditions, and taking the quasi-continuous temperature or strain field distribution information as a label of a data training set. The method breaks through the limitation of the time domain sampling rate on the spatial resolution, saves the data storage space, reduces the calculation time consumption of the temperature or strain field, and improves the demodulation precision of the physical quantity distribution information.

The application provides a kind of optical fiber pressure sensor demodulation method and device for sensing ship-bridge impact force, and relates to the field of optical fiber sensing technology.The method comprises: constructing an optical fiber pressure sensor demodulation system, an initial multi-modal model based on a double-branch radial basis function neural network, and using a hybrid optimization algorithm including an improved adaptive particle swarm global exploration and an enhanced sparrow search local optimization.In the global stage, a nonlinear adaptive PSO is used to obtain the global optimal solution, and in the local stage, the solution is fine-tuned by SSA and dynamic refocusing is achieved using multi-modal monitoring to obtain the optimal solution of the model.The characteristic vector is input into the model, the analytic signal is obtained by Hilbert transform, the envelope is extracted by extracting the modulus, and the real-time pressure prediction value is output by the weighted fusion layer.The application can significantly improve the convergence speed and accuracy of nonlinear spectral inversion, and meet the demand for real-time and high robustness monitoring of local high pressure in ship-bridge impact scenarios.

The invention relates to the technical field of optical fiber ultrasonic sensing, and discloses an optical fiber ultrasonic sensor demodulation system based on LMM-EF. The demodulation system jointly uses a broadband light source and a dense wavelength division multiplexer to realize wavelength division multiplexing of two paths of narrowband optical signals, optimizes an ellipse fitting process through a Levenberg-Marquardt method, introduces an N-order unit matrix I and a damping coefficient alpha, updates the value of alpha according to the approximation degree of a Jacobian matrix and an elliptic equation, and finally achieves the purpose of narrowband optical signal demodulation. And the stability of the second derivative is improved to greatly reduce the occurrence of ill-conditioned problems in the fitting process, so that the fitting iteration mode is between the Newton method and the gradient descent method. Ellipse fitting of Lissajous figures of two interference signals is realized by minimizing the sum of squares of errors between data points and functions, the fitting precision of an ellipse fitting algorithm to short arc signals is improved, and the problem that a traditional dual-wavelength demodulation system based on the ellipse fitting algorithm is not suitable for weak sound signal solution is solved. And the detection range of the optical fiber F-P ultrasonic sensing technology is expanded.

The invention relates to the field of isolation switch driving control, in particular to a demodulation device for isolation switch driving control and a driving method of the demodulation device. Waveform shaping is carried out on an input modulation signal, the modulation signal is converted into a high-frequency square wave signal, high-frequency components are filtered out through a low-pass filter, and a stable digital signal is obtained; the method comprises the following steps: carrying out delay processing on a modulation signal containing logic jump to ensure that the delay width can cover the low level width of the signal, controlling a clock of a delay timer through a control logic module according to the low level part of the modulation signal to avoid generating a rising edge signal, and outputting a reset pulse signal and a driving low signal when a specific condition is met. When other conditions are detected, the register is triggered to sample a high-level signal and output a driving high signal, interference can be effectively filtered, the amplitude and the phase of the signal are kept stable, and low delay is achieved in the signal conversion process so as to ensure the accuracy of signal transmission.

This application provides an IQ imbalance calibration method, apparatus, signal transmitter, and zero-IF transceiver. The method includes: acquiring a reference baseband signal and a radio frequency (RF) signal output by the IQ modulation channel based on the reference baseband signal, and converting the RF signal into a modulation baseband signal; reconstructing the modulation baseband signal to generate a baseband feedback signal characterizing the distortion of the IQ modulation channel; obtaining pre-distortion parameters for compensating for IQ imbalance based on the reference baseband signal and the baseband feedback signal; performing pre-distortion processing on the reference baseband signal using the pre-distortion parameters to generate a baseband pre-distortion signal; and performing imbalance calibration on the IQ modulation channel based on the baseband pre-distortion signal. Because the IQ modulation channel is calibrated, the image rejection ratio and error vector amplitude performance of the output signal can be improved, thus increasing the calibration accuracy of the IQ modulation channel.

The invention discloses an optically integrated optical fiber current transformer, and belongs to the technical field of optical fiber sensing. The optical fiber current transformer comprises an integrated optical chip, a lambda / 4 wave plate, a sensing optical fiber ring, a reflecting mirror and a signal processing system, in the integrated optical chip, a light beam emitted by a superradiation light source passes through a first beam splitting / beam combining waveguide, then is subjected to mode filtering through a polarization / polarization waveguide, is split through a second beam splitting / beam combining waveguide and is modulated by a phase modulator in two paths, one path is modulated and then is subjected to mode conversion through a mode conversion waveguide, and the other path is modulated through a phase modulator. After being combined by the polarization beam combining / beam splitting waveguide, the light enters the optical fiber through the optical fiber waveguide coupler; the two beams of light pass through the lambda / 4 wave plate and the sensing optical fiber ring in the optical fiber, then are reflected by the reflector and return along the same path, the two beams of light interfere with each other in the integrated optical chip and then are combined to enter the photoelectric detector to form a photocurrent signal, and the photocurrent signal is input into the signal processing system to be demodulated. And miniaturization and integration of the optical fiber current transformer are realized.

The invention provides a fiber grating sensor demodulation system based on a dynamic peak searching algorithm, and the method comprises the steps: receiving a to-be-demodulated laser signal transmitted by a multi-channel photodiode, carrying out the moving average filtering of the to-be-demodulated laser signal, and obtaining a filtered laser signal, and judging whether peak candidate points greater than the laser signal threshold exist in the plurality of peak candidate points, and if yes, taking the peak candidate points greater than the laser signal threshold as a first set. A peak position is determined based on each peak candidate point in the first set and the corresponding first weight. If not, whether the number of the peak value candidate points is larger than the minimum peak value number or not is judged. And if yes, calculating a weighted average peak value position, and taking the weighted average peak value position as the peak value position of the laser signal to be demodulated. And demodulating the fiber grating sensor based on the peak position. According to the method provided by the invention, accurate peak searching can be carried out in the demodulation process of the fiber grating sensor.

The wavelength assignment method of the optical fiber sensing spectrum detection module based on scanning light source disclosed in the present invention belongs to the field of optical fiber sensing. The optical fiber sensing spectrum detection module is an optical fiber sensing spectrum detection module based on diffraction grating spectrometry and array detector. The present invention outputs a narrowband wavelength covering the entire C+L working band of the assigned spectrum detection module in a scanning manner, and utilizes the characteristic that the output wavelength interval of the high-precision scanning light source is much higher than the sampling rate of the spectrum detection module to form a series of center wavelength positioning arrays for each pixel, and then uses the zero-crossing point of the linear fitting function to locate the center wavelength, which is used to assign wavelengths to the pixels of the optical fiber sensing spectrum detection module based on diffraction grating spectrometry and array detector. The present invention can solve the problem of a small number of standard light sources in the working band, and can improve the problem of spectral profile broadening caused by pixel width leading to peak position blur, thereby improving the assignment accuracy of the full band range.

The invention belongs to the technical field of optical fiber temperature measurement, and particularly relates to an overhead line composite optical fiber temperature measurement method, device and equipment and a medium. The method comprises the following steps: firstly, acquiring Brillouin gain spectrum data along the axial direction of an optical fiber; then, the Brillouin frequency shift is directly calculated by adopting a gravity center method, iterative fitting is not needed, and the processing speed is remarkably improved; further, an error estimation formula is obtained through theoretical derivation, and the measurement error is rapidly evaluated according to the sweep frequency center frequency, the frequency shift value and the line width; and finally, temperature distribution is demodulated based on the linear relationship between the frequency shift and the temperature, and a temperature measurement error is calculated in combination with a frequency shift error. The method solves the problem that the traditional method is difficult to balance among speed, precision and efficiency, realizes rapid and reliable temperature measurement with an evaluable result, and is suitable for occasions needing real-time monitoring, such as overhead lines.

The application discloses a kind of enhanced deep residual neural network receiving methods for non-orthogonal superimposed pilot transmission, belong to wireless communication technical field.For the coupling interference problem caused by pilot and data high overlap in non-orthogonal superimposed pilot system, a receiver architecture based on physical feature reconstruction and residual network optimization is proposed.The method comprises: extracting the amplitude and phase characteristics of the received signal and the pilot by amplitude-phase conversion operator, respectively, and splicing to construct a multi-dimensional input feature map;Nonlinear mapping is carried out using a cascaded 6-layer enhanced residual convolutional network, wherein the frequency coherence between subcarriers is captured by expanding the time-frequency domain receptive field using dilated convolution, and the key features are adaptively weighted using squeezing and excitation modules;Finally, the bit-level log-likelihood ratio estimate is output, and the original bits are recovered by decoding.The application is suitable for high-speed dynamic scenarios, has less parameters and low complexity, can efficiently demodulate under complex interference multi-stream transmission, and meets the demand of 6G high spectral efficiency.

The invention relates to a PGC-Atan demodulation method and system for directly calculating phase modulation depth, and belongs to the technical field of sensor phase demodulation, the method is based on the corresponding relation between the phase change caused by laser modulation and the interference light intensity, and the phase modulation depth is calculated by monitoring the intensity change of interference signals under different laser modulation parameters. And the phase modulation depth is directly calculated. The demodulation system carries out high-frequency modulation on a laser light source by adopting an internal modulation mode, and eliminates the influence of associated amplitude modulation by utilizing synchronous A / D (Analog to Digital) acquisition. The obtained interference signals are mixed and multiplied with carrier frequency-doubled sine signals, carrier frequency-doubled cosine signals and carrier frequency-doubled cosine signals respectively, and a pair of orthogonal signals containing the phase of the signal to be measured is obtained through low-pass filtering and signal processing. And performing arc tangent operation and high-pass filtering on the orthogonal signal to realize accurate demodulation of the signal to be measured. According to the invention, accompanying amplitude modulation elimination and direct calculation and compensation of carrier modulation depth and phase difference are carried out, and the demodulation accuracy is obviously improved.

The invention discloses a signal demodulation method, device and equipment, a medium and a product. The method comprises the following steps: acquiring an echo signal, and a local oscillator signal and a synchronization signal corresponding to the echo signal; coherent frequency mixing is carried out on the echo signal and the local oscillator signal, and a beat frequency combination is determined; constructing a beat frequency signal set in the demodulation area according to the demodulation area corresponding to the synchronization signal and the beat frequency combination; determining an actual beat frequency based on the echo signal and the beat frequency signal set; and demodulating the target information based on the actual beat frequency. A demodulation area is determined through a synchronization signal, a beat frequency signal set in the demodulation area is constructed, and the actual beat frequency is determined through an echo signal. Accurate determination of the beat frequency signal frequency is realized, and the demodulation accuracy of the target information is further improved.