91 results about "Quadrature demodulation" patented technology

The invention relates to the technical field of ground resistance detection, in particular to a single-core cable ground resistance detection method capable of resisting strong power frequency interference. High-frequency signals are injected in a non-contact mode through a coupling type capacitor clamp, background voltage and current signals are collected firstly, and injection frequency far away from power frequency and harmonic waves is selected through Fourier analysis; cancelling background noise by adopting a normalized least mean square adaptive filter to generate an enhanced signal; the signal is down-converted to a base band through digital quadrature demodulation, a Kalman filter estimates the amplitude and the phase in real time, and the state and noise parameters are periodically calibrated through a compressed sensing algorithm; and finally, loop impedance is calculated according to the voltage and current amplitudes and the phase difference to obtain grounding resistance. The method has the advantages of being non-contact, high in safety, strong in anti-interference capability, high in measurement precision and the like, and is suitable for monitoring the grounding state of the cable in a complex electromagnetic environment.

The invention belongs to but is not limited to the technical field of signal extraction, and particularly relates to a gas storage wellbore leakage sound wave signal extraction method and system based on distributed optical fibers, and the method comprises the steps: S1, hardware platform construction: constructing a hardware platform based on a DAS technology; s2, data demodulation: a digital orthogonal demodulation technology is adopted in the demodulation process, and the collected data is decomposed into two mutually orthogonal components, so that phase information is extracted; and S3, shaft leakage sound wave signal extraction: performing algorithm processing according to the demodulated phase information. Compared with the originally collected wellbore leakage sound wave signal, the similarity between the extracted signal and the actual wellbore leakage sound wave signal is higher, and the similarity is mainly characterized in that the difference value of the average amplitude is reduced from 0.21 rad to 0.03 rad, the mean square error is reduced from 0.55 rad2 to 0.17 rad2, and the signal-to-noise ratio is increased by 16.9 dB.

The invention provides an anti-interference sound signal data extraction method based on energy data perception, and belongs to the technical field of underwater sound signal processing, and the method comprises the steps: carrying out the A / D sampling and digital orthogonal demodulation of a received sound signal, and obtaining a baseband signal; performing low-pass filtering and downsampling on the baseband signal to obtain a preprocessed signal; performing matched filtering on the pre-processed signal by using a reference signal; the key improvement lies in that a local energy estimation function of a preprocessed signal is calculated, and normalization processing is carried out on a matched filtering result and the energy estimation function to obtain a normalized detection signal. The method effectively suppresses the shielding effect of a strong interference signal on a weak target signal under a non-orthogonal reference signal and a strong near-end and weak far-end scene, remarkably reduces the misrecognition probability, and improves the accuracy and reliability of the extraction of a long-distance and low-signal-to-noise-ratio target beacon signal in a complex underwater acoustic environment. The method is suitable for underwater navigation, positioning and communication systems.

According to an embodiment, a circuit is proposed for generating rate and quadrature demodulation signals, incorporating unidirectional hysteresis for negative edges. The circuit features a preliminary stage that amplifies the differential sinusoidal signal from gyroscopic proof mass oscillations; a gain stage for boosting this signal with adjustable hysteresis levels; an output stage delivering a full-swing square wave output; and a customizable offset component to deepen the drop in the non-inverting compared to the inverting signal for the third signal's falling edge.

The invention provides an adaptive control method and system for an accelerator klystron, and electronic equipment, and the method comprises the steps: collecting a reverse wave signal in a microwave signal which is generated by an excitation source, is amplified by the klystron, and is inputted to an accelerating tube, and obtaining the current output frequency of the excitation source; performing I / Q orthogonal demodulation on the reverse wave signal to obtain an I / Q signal, and calculating the frequency deviation between the current resonant frequency of the accelerating tube and the current output frequency of the excitation source; and according to the frequency deviation, outputting a frequency control instruction to the excitation source so as to adjust the output frequency of the excitation source, and enabling the current output frequency of the excitation source to track the current resonant frequency of the accelerating tube. By calculating the frequency deviation and directly outputting the control instruction to adjust the output frequency of the excitation source, the technical problems of control object dislocation and response lag existing in a traditional automatic frequency control system are solved.

The invention relates to a permanent magnet synchronous motor rotor position estimation method based on high-frequency signal injection, and the method comprises the following steps: carrying out the amplitude modulation of a preset high-frequency voltage carrier signal through an orthogonal rotation modulator, and obtaining an injection signal vector; performing voltage excitation on a stator winding of the permanent magnet synchronous motor based on the injection signal vector to obtain a high-frequency current response signal; performing harmonic separation on the high-frequency current response signal through a comb filter bank to obtain a rotor position modulation current component; orthogonal demodulation is carried out on the rotor position modulation current component through a complex demodulator, and a position-dependent phase difference value is obtained; non-linear mapping processing is carried out on the position-dependent phase difference value through an adaptive state observer, a real-time rotor position angle value is obtained, and the key problem of how to effectively extract information related to the rotor position from a high-frequency current response signal is solved.

The invention discloses an optical fiber sensor high-speed demodulation device based on a cascaded Mach-Zehnder interferometer, which adopts a two-stage cascaded Mach-Zehnder interferometer structure, and obtains four-channel output with equal central wavelength intervals by accurately aligning two-stage central wavelengths. And the four-channel signal is utilized to carry out orthogonal demultiplexing on a spectral signal of the optical fiber sensor. In a digital domain, an orthogonal demodulation algorithm for phase demodulation of an optical fiber sensor is provided, and the demodulation speed is only limited by a digital sampling rate. Compared with a traditional spectrum demodulation algorithm, the scheme has the advantages of being high in demodulation speed, wide in working frequency band, easy to implement and the like.

The invention provides a breast cancer tissue anomaly detection method based on multi-frequency electrical impedance dynamic analysis, and the method comprises the steps: generating a multi-frequency electrical excitation signal covering a preset low frequency to a high frequency, applying the multi-frequency electrical excitation signal to a to-be-detected breast tissue through an electrode array, and synchronously collecting a response voltage signal. Orthogonal demodulation is carried out on the collected voltage signals, real and imaginary components of each frequency point are separated, a complex impedance value is calculated, and a multi-frequency impedance spectrum is generated. Feature vectors including amplitude-frequency characteristic slope, phase-frequency characteristic extreme point position, high-frequency-band impedance attenuation rate and the like are extracted from the impedance spectrum, a pre-trained dynamic judgment model is input to calculate a tissue anomaly index, and finally whether the mammary gland tissue is abnormal or not is judged according to a comparison result of the anomaly index and a preset threshold value. The accuracy of early detection of breast cancer can be improved, and the stability and reliability of detection are enhanced.

This invention discloses a global phase quadrature demodulation method and apparatus for fiber optic sensing data. The method includes: acquiring initial fiber optic sensing IQ data; determining the corresponding direct phase value based on the initial fiber optic sensing IQ data; performing a light source phase correction operation on the direct phase to obtain first processed data; performing a receiver point initial phase correction operation on the first processed data to obtain second processed data; performing a light source linear phase correction operation on the second processed data to obtain third processed data; performing a receiver point linear phase correction operation on the third processed data to obtain fourth processed data; and performing phase dewinding processing and near-DC component removal processing on the fourth processed data to obtain globally phase demodulated data. By analyzing various influencing factors of the initial fiber optic sensing IQ data and adopting corresponding data optimization processing methods, the problems existing in the acquisition process of fiber optic sensing data are overcome, and the accuracy of fiber optic sensing data is improved.

According to an embodiment, a circuit is proposed for generating rate and quadrature demodulation signals, incorporating unidirectional hysteresis for negative edges. The circuit features a preliminary stage that amplifies the differential sinusoidal signal from gyroscopic proof mass oscillations; a gain stage for boosting this signal with adjustable hysteresis levels; an output stage delivering a full-swing square wave output; and a customizable offset component to deepen the drop in the non-inverting compared to the inverting signal for the third signal's falling edge.

The invention relates to the technical field of microscopic imaging, and particularly provides a stimulated Raman scattering microscopic imaging system capable of simultaneously scanning double Raman frequency shift spectrums, which comprises a laser light source driving and modulating unit and a signal detecting and data processing unit, the laser light source driving and modulating unit comprises a dual-channel laser synchronous excitation module, a light beam polarization regulation and power distribution module, a pulse broadening and spectrum focusing module, a dual-channel dual-phase modulation module, a common-path different-time dual-frequency difference module and a laser scanning and telecentric focusing module; and the signal detection and data processing unit comprises a dual-channel orthogonal demodulation module and a scanning driving and signal synchronous acquisition module. Compared with the prior art, the dual-Raman frequency shift spectrum scanning stimulated Raman microimaging device has the advantages that dual-Raman frequency shift spectrum scanning stimulated Raman microimaging with higher acquisition speed, high resolution and wide spectrum coverage range is realized, and the problem of long time consumption for acquiring the complete spectrum of the to-be-tested sample by the traditional single-frequency resonance spectrum scanning stimulated Raman microimaging is solved.

The application discloses a kind of digital frequency tracking and synchronous sampling control system for resonant gyro, including self-excitation oscillation and automatic gain control device, preamplifier circuit and digital signal processor, digital signal processor includes first A / D conversion unit, second A / D conversion unit, frequency error detection unit FD, phase error detection unit PD, digital control oscillator NCO, sampling frequency generator and quadrature demodulation unit, the vibration signal of drive channel is handled after device output to first A / D conversion unit, conversion obtains the vibration signal after conversion, FD obtains frequency difference by frequency error detection, PD obtains phase difference by phase error detection, NCO is adjusted the frequency and phase of sampling frequency generator according to frequency difference and phase difference in real time, until the resonant frequency and phase of drive channel are tracked;The vibration signal of detection channel is handled after circuit output to second A / D conversion unit, obtains the vibration signal after conversion, and quadrature demodulation unit carries out quadrature demodulation and obtains speed signal.

The application discloses a laser phase noise measurement method based on delay self-heterodyne and digital demodulation, and relates to the technical field of laser measurement, and comprises the following contents: after being adjusted by a variable optical attenuator, to-be-measured laser is divided into a frequency shift arm and a delay arm, the frequency shift arm is frequency-shifted by an acousto-optic modulator, the delay arm is delayed by a delay optical fiber, and original electric beat frequency signals are obtained by a balanced photoelectric detector after the two arms are coupled; homologous and synchronous quadrature demodulation is carried out on the original electric beat frequency signals, envelope credibility judgment and abnormal sample repair are combined, and a continuous differential phase sequence is obtained; actual optical time delay is determined according to the beat frequency spectrum characteristics and the continuous differential phase sequence, and a differential phase power spectral density is formed; then, transmission relationship conversion is carried out according to the actual optical time delay, bounded spectrum compensation is implemented on a zero point neighborhood and a low credibility frequency point, and an intrinsic phase noise power spectral density is obtained. The application can improve the stability, continuity and result credibility of phase noise measurement under the condition of short delay.

This invention provides a low-crosstalk signal demodulation device and method for fiber optic laser communication, belonging to the field of fiber optic communication technology. The device includes a fiber optic signal input port, an optical circulator, a polarization beam splitter / combiner module, a balanced photodetector unit, a low-noise amplification and quadrature demodulation module, an adaptive crosstalk cancellation unit, a MIMO equalization and decision unit, and a digital signal output port, connected in series according to the signal flow direction. It also includes a crosstalk monitoring and feedback unit bidirectionally connected to the low-noise amplification and quadrature demodulation module, the adaptive crosstalk cancellation unit, and the MIMO equalization and decision unit. This invention, employing the aforementioned low-crosstalk signal demodulation device and method for fiber optic laser communication, overcomes the limitations of traditional single-domain crosstalk suppression. Through the synergistic effect of optical path, circuit, and algorithm layers, it effectively suppresses crosstalk caused by multi-channel multiplexing, polarization mode dispersion, and backscattering, significantly improving demodulation accuracy, anti-interference capability, and system stability.

A system and method for using quadrature demodulation to detect an event associated with a substrate. The method includes receiving an ultrasound signal associated with a substrate. The method includes performing quadrature demodulation of the ultrasound signal to generate an in-phase signal and a quadrature signal. The method includes detecting an event associated with the substrate based on the in-phase signal and the quadrature signal. The method includes providing a notification indicating the event.

A system and method for using quadrature demodulation to detect an event associated with a substrate. The method includes receiving an ultrasonic signal associated with a substrate. The method includes performing quadrature demodulation of the ultrasonic signal to generate an in-phase signal and a quadrature signal. The method includes detecting an event associated with the substrate based on the in-phase signal and the quadrature signal. The method includes providing a notification indicating the event.

The application discloses a kind of dual-frequency modulation transfer spectroscopy laser frequency stabilization device and method, construct the dual-frequency modulation signal including first frequency component and second frequency component, according to dual-frequency modulation signal driving fiber electro-optic phase modulator to laser is carried out dual-frequency electro-optic phase modulation;Photoelectric detector carries out detection to the polarized beam splitter output light and obtains saturated absorption signal, to saturated absorption signal in turn carries out quadrature demodulation and low-pass filter processing and obtains first error signal and second error signal, first error signal and second error signal are superimposed to obtain dual-frequency error signal;Further, tunable laser is carried out closed-loop feedback control, realizes laser frequency stabilization.The application obtains two different frequency components error signal using dual-frequency modulation transfer spectroscopy detection technology, improves slope and intensity by adding operation, improves frequency discrimination sensitivity and anti-interference ability, is conducive to peak search determination and realizes the precision locking of laser frequency to rubidium absorption peak, with good practicability.

The invention discloses an in-phase and quadrature demodulation phase modulation optical heterodyne frequency stabilization system for suppressing RAM, and relates to the technical field of laser frequency stabilization, comprising a laser, an electro-optic modulator, a circulator, an optical resonant cavity, a photodetector, a phase shifter, a mixer, an adder, a low-pass filter, a signal generator and a signal acquisition and processing module; laser light emitted by the laser enters the circulator after being modulated by the electro-optic modulator, the circulator receives the reflected light of the optical resonant cavity and emits it into the photodetector, and all error signals are obtained through the mixer and the low-pass filter, all error signals are added through the adder, and then input into the signal acquisition and processing module and fed back, so that the frequency of the laser light emitted by the laser is locked to the resonant frequency of the optical resonant cavity; the frequency stabilization system modulates the laser phase in the electro-optic modulator by introducing multiple modulation frequencies, so as to suppress the influence of RAM noise on the frequency stabilization.

Device comprising: a quadrature demodulator configured to receive an input signal, a first reference signal, and a second reference signal in quadrature with the first reference signal, the quadrature demodulator further configured to produce a plurality of output signals from the input signal and the first and second reference signals, the plurality of output signals indicative of the amplitude and phase of the input signal; one or more inverting circuits, the inverting circuits having a first and a second programmable output polarity, the plurality of output signals being output by the quadrature demodulator when the inverting circuits are set to the first programmable output polarity, the plurality of output signals being inverted and output by the quadrature demodulator when the inverting circuits are set to the second programmable output polarity, and a controller (508) coupled to the quadrature demodulator, the controller (508) being configured to determine the amplitude and phase of the input signal according to the plurality of output signals, the one or more inverting circuits being configured to be coupled to the controller (508), the controller (508) further being configured to set the inverting circuits to the first programmable output polarity while determining first values ​​of the plurality of output signals, set the inverting circuits to the second programmable output polarity while determining second values ​​of the plurality of output signals, and determine one or more error values ​​from the first and second values ​​of the plurality of output signals, the controller (508) further being configured toto determine the error values ​​by subtracting the first values ​​of the plurality of output signals from the second values ​​of the plurality of output signals, wherein determining comprises subtracting the second values ​​of the plurality of output signals from respective ones of the first values ​​of the plurality of output signals to produce the one or more error values.

The present application relates to the technical field of precision phase measurement and digital signal processing, and particularly relates to a method and system for suppressing spectral aliasing and nonlinear distortion. The beat frequency signal is preprocessed and spectrum is constructed to obtain a normalized spectrum; peak value search is performed in a preset target frequency range to identify beat frequency, side frequency and pilot frequency signals to form an effective spectrum line set; nonlinear parasitic components are calculated to obtain folded parasitic spectrum lines, and the parasitic spectrum lines to be evaluated are obtained through constraint screening; branch processing is realized through suppression standard judgment, and selective narrowband notch suppression is performed on the parasitic spectrum lines meeting the conditions; digital heterodyne quadrature demodulation and low-pass filtering are performed on the signals before and after processing; and the suppression effect quantitative evaluation is completed according to the phase error and phase noise index, and the parameters are dynamically adjusted to realize the working condition adaptive optimization. The advantage lies in: accurately predicting and suppressing the composite interference, protecting the integrity of the effective signal, significantly improving the phase measurement accuracy and robustness, and widely applying to various scenes.

Method and system for automatic modulation classification (AMC) use time-series voltage signals representative of radio frequency (RF) signal envelope and frequency components as input features to a deep learning-based neural network, which enables classification of both modulation type and symbol rate without requiring in-phase and quadrature (IQ) demodulation. A feature extraction circuit captures RF signal envelope amplitude and frequency using stub-based sensing, and a Long Short-Term Memory (LSTM) neural network processes these features in a digitized form to classify the modulation and symbol rate with high accuracy and minimal latency.

The application provides an anti-interference acoustic signal data extraction method based on energy data sensing, and belongs to the technical field of underwater acoustic signal processing. The method comprises the following steps: A / D sampling and digital quadrature demodulation are performed on a received acoustic signal to obtain a baseband signal; low-pass filtering and down-sampling are performed on the baseband signal to obtain a pretreated signal; the pretreated signal is matched filtered by using a reference signal; a key improvement lies in that a local energy estimation function of the pretreated signal is calculated, and the matched filtering result is normalized with the energy estimation function to obtain a normalized detection signal. Through energy sensing normalization, the application effectively suppresses the shielding effect of strong interference signals on weak target signals due to non-quadrature reference signals and the "near-end strong and far-end weak" scene, significantly reduces the false recognition probability, and improves the accuracy and reliability of extracting a long-distance and low signal-to-noise ratio target beacon signal in a complex underwater acoustic environment. The application is suitable for underwater navigation, positioning and communication systems.

This application discloses a fully digital magnetic field measurement device and method, relating to the field of magnetic field measurement technology. The device generates a constant AC-DC superimposed current signal with adjustable frequency and amplitude, and outputs it to a Hall sensor placed in the magnetic field to be measured. It acquires the Hall voltage generated by the Hall sensor and performs analog-to-digital conversion to obtain a digital Hall signal. The digital Hall signal is quadrature demodulated to extract the in-phase and quadrature components. The magnetic field strength amplitude and phase are calculated based on the in-phase and quadrature components. The current is sampled in real time, and a closed-loop control signal is generated based on the deviation between a preset target current value and the actual sampled value to adjust the AC-DC superimposed current amplitude. Through a fully digital signal processing architecture and closed-loop control and output, high-precision, high-speed, and low-noise measurement of magnetic field strength and direction is achieved.

The utility model provides a frequency hopping zero intermediate frequency receiver circuit, which is characterized in that a radio frequency amplification circuit is connected with the input end of a power distribution circuit through a controllable attenuation circuit, the output end of the power distribution circuit is respectively connected with the input ends of two orthogonal demodulation circuits, the output end of a first PLL circuit is connected with the local oscillation end of a first orthogonal demodulation circuit, and the output end of a second PLL circuit is connected with the local oscillation end of a second orthogonal demodulation circuit. The output end of the second PLL circuit is connected with the local oscillation end of the second orthogonal demodulation circuit; two outputs of the first orthogonal demodulation circuit are respectively connected with the input end of the first baseband pre-amplification circuit, and two outputs of the second orthogonal demodulation circuit are respectively connected with the input end of the second baseband pre-amplification circuit; the two output ends of each baseband pre-amplification circuit are respectively connected with the input end of the electronic switch circuit, and the output end of the electronic switch circuit is connected with the final-stage amplification circuit through the baseband filter circuit. The PLL load is not changed at the switching moment of the electronic switch, the influence of PLL load traction can be obviously relieved, and the frequency switching time is reduced by more than 80% compared with that of a traditional ping-pong phase-locked loop.

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 high-precision capacitive displacement sensor based on double ADC switch proportional demodulation. According to the high-precision capacitance displacement sensor based on double-ADC switch proportional demodulation, the analog front-end circuit is used, a refined circuit model is established, modulation noise can be reduced, and the capacitance resolution of analog modulation can be improved; by using the double-ADC switch proportion measurement circuit, secondary alternate acquisition and reconstruction of modulation signals and carrier signals can be realized, so that gain fluctuation caused by carrier generation modules such as ADCs and DACs is inhibited; by using the digital quadrature demodulation circuit, the phase error introduced in the demodulation process can be reduced or eliminated; the bad influence of the DAC carrier gain and the ADC gain on the finally output baseband signal is small, the included phase error introduced in the demodulation process is small, and high-precision displacement detection can be achieved. The displacement sensor is widely applied to the technical field of displacement sensors.

The invention discloses a quadrature demodulation method, system, device and medium, and relates to the technical field of decoding, and the quadrature demodulation method comprises the following steps: processing a sinusoidal signal and a cosine signal through a quadrature DSM modulator, and carrying out down-conversion processing on a signal output by the quadrature DSM modulator to obtain an intermediate frequency signal; obtaining an orthogonal tracking signal, and calculating an intermediate frequency conjugate signal corresponding to the intermediate frequency signal and an orthogonal conjugate signal corresponding to the orthogonal tracking signal; determining a first product of the intermediate frequency signal and the orthogonal conjugate signal, and determining a second product of the orthogonal tracking signal and the intermediate frequency conjugate signal; and taking the difference between the first product and the second product as an orthogonal demodulation result. The technical scheme of the invention aims to solve the technical problem of low signal-to-noise ratio of useful signals in the existing demodulation technology.

The present disclosure relates to an ultrasonic sensing device. A system and method for detecting events associated with a substrate using orthogonal demodulation. The method includes receiving an ultrasonic signal associated with a substrate. The method includes performing quadrature demodulation on the ultrasound signal to generate an in-phase signal and a quadrature signal. The method includes detecting an event associated with the substrate based on the in-phase signal and the quadrature signal. The method includes providing a notification indicative of an event.

The application discloses a nonlinear fitting method and system of an impedance equivalent model, voltage and current data are collected at configured frequency points through a frequency sweeping hardware system, corresponding impedance values are obtained through orthogonal demodulation for the data at each frequency, a matched impedance model is selected from a plurality of preset impedance equivalent circuits, a plurality of initial model parameters are predicted through a multi-physical field coupling initial value prediction algorithm, the initial model parameters are combined with a parameter physical constraint optimization strategy, and an optimal solution is obtained through nonlinear least square fitting, so that the algorithm has the advantages of accelerating the convergence speed and reducing the requirement for computing power, model parameters are automatically adjusted in the algorithm operation process, errors between model prediction values and actual measurement values are minimized, and the model parameters are continuously adjusted, so that accurate fitting of the equivalent model is realized.

The invention discloses a chaos incoherent underwater acoustic communication demodulation method, a chaos incoherent underwater acoustic communication demodulation system and a chaos incoherent underwater acoustic communication demodulation product based on channel weighting. The method comprises the following steps: 1, receiving a training sequence of an underwater acoustic chaos incoherent signal, and adaptively performing underwater acoustic channel estimation through an affine projection algorithm in combination with a copy signal to obtain a frequency domain channel response value; step 2, calculating energy of the underwater acoustic channel in a narrow band with a frequency modulation point to be demodulated as a center, and taking the energy as a demodulation weighted value; step 3, in an incoherent demodulation stage, calculating energy of each frequency point to be demodulated based on an orthogonal demodulation method, and then multiplying the energy by the demodulation weighted value calculated in the step 2 to obtain a demodulation energy value of each frequency point; and step 4, obtaining a final demodulation result of each frequency modulation point to be demodulated through hard decision. According to the invention, the chaotic incoherent signal is adopted, the influence of the underwater acoustic Doppler effect is less, and the confidentiality is better; and the influence of a channel on signal demodulation is fully considered, and compared with a traditional demodulation method, the method has better robustness.