18 results about "Amplitude demodulation" patented technology

The invention relates to the technical field of optical fiber sensing, in particular to a dual-channel information fusion vibration positioning device and method based on a dual-k method, and aims to improve a traditional single-channel amplitude demodulation phi-OTDR (AD-phi-OTDR) system to obtain a device with a dual-channel phase-sensitive optical time domain reflectometer module. Firstly, vibration signals are collected through a dual-channel amplitude demodulation phi-OTDR system, then the optimal sampling number is designed through the relation between the vibration frequency and the sampling period, the time consumed by system vibration positioning is shortened, the operation efficiency of the system is improved, then vibration positioning is conducted through a dual-k method, and finally vibration is judged through dual-channel information fusion. According to the invention, the authenticity of the signal is improved through dual-channel cross validation. And a dual-channel data fusion mechanism is used for effective discrimination, so that the anti-interference performance of the system is improved, and the reliability of vibration signal discrimination is further improved.

The invention provides a wind turbine generator rotating shaft fault monitoring method and system based on pulse amplitude modulation. The method comprises the steps that pulse amplitude modulation signals of a rotating shaft are collected through a pulse amplitude modulation measuring device installed on a target shaft section of the rotating shaft of a measured wind turbine generator; performing amplitude demodulation on the pulse amplitude modulation signal to obtain an eccentric compound vibration component of the rotating shaft; carrying out discretization processing to obtain a composite vibration component sequence of a discrete time domain, then carrying out Fourier transform on the sequence of the discrete time domain to obtain phase differences, and extracting vibration amplitudes and amplitude characteristic parameters of each vibration component under different frequencies; and monitoring a misalignment abnormal state of the rotating shaft according to the vibration amplitudes, the amplitude characteristic parameters and the phase differences of the vibration components under different frequencies. According to the technical scheme, signals are collected through the pulse amplitude modulation measuring device, and high-precision monitoring and accurate fault type identification of the misalignment of the rotating shaft of the wind turbine generator are realized in combination with amplitude demodulation and frequency domain analysis.

The application provides a method, device and storage device for inhibiting fading interference, selects a main lobe and two first-order side lobes, extracts three sub-bands by using a filter with the same width as the main lobe, adds the intensity of three curves obtained by performing inverse Fourier transform on the three sub-bands by using a rotation vector summation method to obtain a new signal, extracts the phase information of each vibration point on the new signal curve by amplitude demodulation, sets a threshold range according to the corresponding relationship between the amplitude and the phase of Rayleigh scattering, selects the phase, retains the phase outside the threshold range, averages the phase in the threshold range, thereby avoids the wrong phase point, and obtains the final phase demodulation image of the vibration point for eliminating fading interference. The application has the beneficial effects that: the coherent fading is eliminated without multiple frequency data, the detection times are reduced, the cost is reduced, the real-time demodulation speed is accelerated, and the wrong phase demodulation is avoided.

The invention relates to an anti-impact continuous self-adaptive PI control method and system for a micro-hemispherical resonator gyro, and the system comprises a micro-hemispherical resonator module, an amplitude demodulation module, an NCO module, a control variable calculation module, an impact index calculation module, a continuous self-adaptive PI control module, a saturation output detection module, and an amplitude modulation module. The micro-hemispherical resonance module is used for outputting a digital signal; the amplitude demodulation module is used for resolving a core characteristic quantity representing the motion state of the harmonic oscillator; the amplitude modulation module is used for modulating and forming a driving voltage; the NCO module is used for providing an original quantity for the control variable calculation module; controlling a variable calculation module to calculate core parameters; the impact index calculation module calculates a normalized impact index; the continuous self-adaptive PI control module calculates continuously changing proportional gain and integral gain; and the saturation output detection module outputs limited amplitude. According to the invention, the control performance in the impact environment is improved, the adaptability and stability of the system are enhanced, and the anti-saturation performance of the system is improved.

This invention relates to a symbol detection method for an orthogonal time-frequency spatial modulation system combining LMMSE and MRC, belonging to the field of mobile communication. Based on the orthogonal time-frequency spatial OTFS modulation system, linear minimum mean square error (LMMSE) detection is first performed in blocks in the time domain. The detection results are then combined and converted to the time-delay-Doppler domain for orthogonal amplitude demodulation. The demodulated results are then converted to the time-delay-time domain and used as the initial values ​​for the maximum ratio combining (MRC) detection algorithm in the time-delay-time domain, thereby improving the bit error rate performance of the MRC detection method. Simulation experiments verify the effectiveness of this invention. Compared with other initialization detection methods, this method has a lower bit error rate at high communication rates and also exhibits superior performance in high-speed mobile scenarios.

An amplitude demodulation implementation method applied to a secondary radar, the method comprising: performing frequency mixing on a reply signal to obtain an intermediate frequency signal; quantizing the intermediate frequency signal; performing quadrature demodulation on the quantized intermediate frequency signal to obtain a digital amplitude value, and using a piecewise linear calculation method to obtain a logarithmic digital amplitude. The logarithmic compression processing function of the secondary radar for a reply signal is implemented by an FPGA; after intermediate frequency digitization of the reply signal, a digital amplitude value is obtained via quadrature demodulation; and the digital amplitude value is processed in the FPGA by using a piecewise linear calculation method to approximate a logarithmic conversion characteristic, so as to obtain a logarithmic digital amplitude, which is very simple.

The invention discloses a distributed optical fiber sensing data processing method and system and a storage medium, and the method comprises the steps: carrying out the amplitude demodulation and phase demodulation of optical fiber sensing data at each spatial position, and obtaining a first amplitude demodulation result and a first phase demodulation result at each spatial position; unwinding the first phase demodulation result at each spatial position to obtain a second phase demodulation result at each spatial position; based on the second phase demodulation result at each spatial position, judging whether wrong unwrapping occurs at each spatial position; and if wrong unwrapping occurs at a certain spatial position, correcting the second phase demodulation result at the spatial position by using the first amplitude demodulation result at the spatial position. Therefore, distortion elimination of the phase signal can be realized, and the signal quality is improved.

The invention relates to the technical field of signal modulation, in particular to an analog orthogonal vector amplitude demodulation method and device. The method comprises the following steps of: firstly, performing orthogonal demodulation on a signal to be demodulated by combining an original reference signal VREF to obtain an in-phase signal VINX and an orthogonal signal VINY; and then amplitude demodulation is carried out on the in-phase signal VINX and the orthogonal signal VINY to obtain a final demodulation result VOUT. According to the invention, a first multiplication divider, a second multiplication divider and an addition unit are constructed for amplitude demodulation. According to the analog orthogonal vector amplitude demodulation method provided by the invention, two multiplication dividers and an addition unit are constructed, so that an implicit operation logic combining squaring, addition and feedback is realized, the dynamic range of a demodulation circuit is effectively expanded, and the demodulation efficiency is improved. The core problem that the analog demodulation dynamic range of a traditional explicit operation (direct extraction) structure is insufficient is solved.

The application relates to the fields of sensor technology and coagulation monitoring and relates to a QCM sensor coagulation detection method and system based on amplitude detection, which comprises the following steps: a DDS sweep source outputs a sweep signal; when blood coagulates on the surface of a quartz crystal, the resonance frequency of the quartz crystal changes; a QCM sensor monitors the sweep signal and reacts according to the signal amplitude change of the resonance frequency; the DDS sweep source gradually adjusts the frequency, and the QCM sensor monitors the signal amplitude change; an amplitude demodulation module detects the signal amplitude in real time and feeds back the signal to a single-chip microcomputer; the single-chip microcomputer controls the sweep parameters to control the sweep process of the DDS sweep source, processes the received signal, outputs a measurement result and completes coagulation function monitoring. According to the relationship between the load quality and the signal amplitude change, the amplitude fluctuation in the coagulation process is monitored in real time, so that the resonance frequency change curve of the quartz crystal under different coagulation functions is reflected, the detection precision and stability are improved, and the application prospect is wider.

The invention discloses a signal demodulation method and system based on an ion coherent vibration state, and belongs to the technical field of communication, and the method comprises the steps: obtaining coherent vibration state ions and standard signals of different modulation types, enabling the coherent vibration state ions to fluctuate along with the code element change of the standard signals, and obtaining standard fluctuation ions; measuring standard fluctuation ions to construct a modulation feature library; acquiring a to-be-demodulated signal, and enabling the coherent vibration state ions to fluctuate along with the code element change of the to-be-demodulated signal to obtain fluctuating ions; based on the modulation feature library, performing matching identification on the amplitude and the phase of the fluctuating ions to complete signal demodulation on the to-be-demodulated signal: when the amplitude jumps and the phase is unchanged, performing amplitude demodulation; when the amplitude and the phase jump at the same time and jump directions are opposite, phase demodulation is carried out; and when the jump of the amplitude and the phase presents a sine periodic rule, frequency demodulation is carried out. According to the method disclosed by the invention, the demodulation accuracy and applicability of the communication system can be improved.

The present invention is an Au-Ni-Pd-Pt-based noble metal alloy which contains from 1.5 at% to 47 at% (inclusive) of Au, from 4 at% to 57 at% (inclusive) of Ni, from 1 at% to 43.5 at% (inclusive) of Pd, and from 6 at% to 58.5 at% (inclusive) of Pt, and which further contains from 0.003 at% to 8 at% (inclusive) of B. The noble metal alloy according to the invention achieves high hardness by means of a modulated structure based on amplitude-modulated decomposition and / or an ordered phase based on ordering. According to the present invention, in addition to the aforementioned high hardness, the ductility of the recrystallized structure is improved by adding B. In addition, the noble metal alloy of the present invention may optionally contain Cu, an added metal alpha (In, Sn, Sb), and an added metal beta (Al, Ti, Zr, Hf).

The utility model discloses an eddy current flaw detection circuit for a steel rail. The eddy current flaw detection circuit comprises a control CPU, an excitation pulse generator, an excitation pulse voltage regulation module, an eddy current sensor and a signal demodulation module, wherein the control CPU is connected with the excitation pulse generator and executes commands issued by a computer, the excitation pulse generator generates excitation pulses, the excitation pulse generator is connected with the excitation pulse voltage adjusting module, and the amplitude value of the excitation pulses is adjusted through the excitation pulse voltage adjusting module. The excitation pulse voltage regulation module is connected with the eddy current sensor, and an alternating electromagnetic field generated by an excitation unit in the eddy current sensor acts on the steel rail; the eddy current sensor is connected with a signal demodulation module, a receiving unit in the eddy current sensor receives an electromagnetic signal fed back by the steel rail, the signal demodulation module carries out amplitude demodulation and phase demodulation, and an analog signal is output to reflect a defect characteristic value. The device is high in detection sensitivity and stability, and the type and frequency of excitation pulses can be flexibly set.

Embodiments of the present application provide a signal processing method, comprising: receiving, by a first device, a second signal from a second device, the second signal being generated based on time clipping and amplitude clipping of a first signal, the first signal being generated based on quadrature amplitude modulation mapping of a first bit sequence; performing, by the first device, quadrature amplitude demodulation mapping processing on the second signal to obtain a third signal, the third signal comprising time clipping noise and amplitude clipping noise; and performing, by the first device, time clipping noise and amplitude clipping noise processing on the third signal according to a successive interference cancellation algorithm to recover the first bit sequence. The method uses the successive interference cancellation algorithm, including decision-directed successive interference cancellation and coded-aided successive interference cancellation algorithm, to eliminate interference noise to recover the signal, which can reduce inter-carrier interference and amplitude clipping noise, and further improve system performance.

The present invention relates to the technical field of eddy current sensors, and proposes a digital signal processing circuit, method, and eddy current displacement sensor device, as well as a device for reducing the temperature drift of a differential eddy current sensor over a wide temperature range using the signal processing method of the present invention. Specifically, the design of a differential probe is utilized to offset the temperature drift of the measured metal, coil, and cable in the system, and a symmetrical high-speed analog-to-digital sampling circuit and a dual-correlation demodulation algorithm are utilized to replace the traditional amplitude demodulation method to digitally demodulate the signal output by the displacement sensor and reduce noise, thereby avoiding the influence of the temperature characteristics of the analog device on the demodulation result. The device can greatly improve the temperature stability of the eddy current sensor and effectively suppress the temperature drift of the eddy current sensor.

The invention belongs to the field of rubidium optical pump magnetometer control, and relates to a terrestrial magnetism measurement rubidium optical pump magnetometer control system and a terrestrial magnetism measurement rubidium optical pump magnetometer control method. The system comprises a 795nm pump laser, a 780nm detection laser, an alkali metal atom gas chamber, a non-magnetic heating module, a magnetic field coil, a photoelectric detector, a signal amplification conditioning module, an amplitude demodulation module, a high-speed frequency discrimination module, a phase error extraction module, a PID (Proportion Integration Differentiation) controller, a DDS (Direct Digital Synthesizer) reference signal and a high-precision constant current source, a magnetic field coil is arranged on the outer side of the non-magnetic heating module, light output by a 795nm pump laser and light output by a 780nm detection laser are emitted into an alkali metal atom gas chamber in an orthogonal mode, and light emitted by the alkali metal atom gas chamber enters a photoelectric detector and a signal amplification conditioning module. A frequency difference value is calculated according to the phase error through a PID controller and is fed back to a high-precision constant current source, and the high-precision constant current source outputs a current drive to a magnetic field coil to realize closed-loop stable control of the rubidium optical pump magnetometer.

The application provides a microwave distance measuring device, which can be applied to the technical field of precision measurement. The microwave distance measuring device comprises: a microwave distance measuring optical path configured to modulate laser light by using a microwave sweep signal to form reference light and signal light; the signal light is sent to a target to be measured, and measurement light formed by reflection of the signal light by the target to be measured is received; based on the reference light and the measurement light, an interference signal with distance information of the target to be measured is formed; a photoelectric detector is configured to convert the interference signal into an electrical signal; a low-pass filter circuit is configured to perform low-pass filtering on the electrical signal; a signal acquisition circuit is configured to perform amplitude demodulation on the filtered electrical signal to obtain an amplitude characteristic signal; and a processor is configured to determine the distance information of the target to be measured based on the amplitude characteristic signal.

This invention discloses a method for estimating the envelope spectrum of ship radiated noise based on spectral whitening, belonging to the field of underwater acoustic signal processing. The method first determines the main frequency band containing the modulation characteristics of the target signal through cyclic modulation spectrum analysis; then, it processes the background noise spectrum within the main frequency band using smoothing, and calculates a spectral shaping factor based on the median of the smoothed spectrum to construct a conjugate symmetric whitening filter; finally, it performs weighted shaping of the target signal spectrum in the frequency domain, and restores the whitened spectrum to the time domain for amplitude demodulation and power spectrum analysis. This invention effectively improves the signal-to-noise ratio (SNR) of broadband envelope spectrum estimation by introducing a spectral whitening mechanism, providing a reliable guarantee for accurately extracting physical characteristics such as the number and rotational speed of ship propellers. Experiments show that this method can improve the average SNR of the envelope spectrum by approximately 7 dB, demonstrating strong engineering practical value.