80 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 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 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.

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 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.

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 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.

The invention discloses an acceleration sensing system and a measurement method thereof, and belongs to the technical field of optical acceleration sensing. Linearly polarized light is output to the transduction module through the laser light source module, the transduction module comprises an MEMS transduction structure and a metasurface unit, and the metasurface unit decomposes the incident linearly polarized light into left-handed circularly polarized light and right-handed circularly polarized light and introduces initial phase modulation related to displacement. The reflected light module reflects the two beams of circularly polarized light back to the metasurface unit, so that the two beams of circularly polarized light pass twice, multiplication of phase modulation is achieved, and the phase modulation amount is increased to 8 times of that of single pass. The photoelectric detection module converts emergent light into two paths of orthogonal electric signals, the signal processing unit eliminates non-ideal errors through an orthogonal compensation algorithm, displacement is calculated through an orthogonal demodulation algorithm, and then acceleration signals are obtained. The method has the advantages of high sensitivity, large dynamic range and excellent low-frequency response, and is suitable for precise measurement scenes such as micro-vibration monitoring.

A method including: scanning a sample over a period of time using an electro-magnetic radiation source, the period of time including a first time period and a second time period, a sample portion of the electro-magnetic radiation source being directed to the sample in a sample arm of an optical interferometric system, and a reference portion of the electro-magnetic radiation source being directed to a reference arm of the optical interferometric system; applying, using a phase modulator, a phase shift comprising a first phase shift and a second phase shift to at least one of the reference portion or the sample portion of the electro-magnetic radiation source, the first phase shift being applied during the first time period and the second phase shift being applied during the second time period, the second phase shift having a difference of 90 degrees from the first phase shift.

This invention discloses a method and system for calculating the ultra-fine spectrum of a sampled signal, belonging to the field of weak signal detection technology. Calculating the spectrum of signals with extremely long sampling times presents problems such as large data volume and high computer memory requirements. This method divides the sampled data sequence of an ultra-low bandwidth modulated signal into segments of equal duration. Each segment is then subjected to quadrature demodulation, filtering, and decimation concatenation. The processed segments are then sequentially concatenated, and finally, a time-frequency transformation is performed to obtain the signal spectrum with ultra-fine frequency resolution. This calculation method significantly reduces the amount of data required for time-frequency transformation, allowing the processing of massive amounts of sampled data to be completed on a conventionally configured computer, yielding signal spectra with frequency resolution at the millihertz or even microhertz level. This allows for the observation and understanding of the extremely low-frequency spectral structure or near-end phase noise of the signal. This calculation method has strong versatility.

The invention belongs to the technical field of radio signal tracking, and particularly relates to a high-dynamic non-coherent direct sequence spread spectrum signal high-precision tracking method. The method specifically comprises the following steps of: after a bit recovery module is arranged in a frequency-locked loop, connecting the frequency-locked loop with a phase-locked loop in series, and then connecting the frequency-locked loop with a code loop and a bit synchronization loop in parallel to form a three-path independent tracking structure; a bit recovery module is set to divide each branch sequence according to the bit hopping phase information to obtain a plurality of subsequences, so that bit hopping does not occur in each subsequence, and a data bit of each subsequence is estimated; and then multiplying the data bits by each branch sequence to obtain a bit recovery sequence, and outputting the bit recovery sequence to an orthogonal demodulation module of a phase-locked loop and a frequency-locked loop integral clearing module respectively.

The invention discloses a surface acoustic wave double-frequency reader structure for multi-level soil temperature and humidity detection and a detection method. Aiming at the condition that the number of levels is large and the device adopts combination of time division multiple access and frequency division multiple access of two frequency bands of 840-845 MHz and 920-925 MHz, a direct digital frequency synthesizer of a transmitting link is mixed with a phase-locked loop to obtain double-frequency excitation signals which comprise two mirror image frequencies of 842.5 MHz and 922.5 MHz, a receiving link constructs a double-frequency channel through two duplexers, and the receiving link is connected with the receiving link through the two duplexers. Meanwhile, echo pulse string signals of all the double-frequency surface acoustic wave devices are received, and the signals are processed in parallel through a double-frequency digital quadrature demodulator to obtain soil temperature and humidity values of all levels. Compared with polling emission of excitation signals with two frequencies and time-sharing information processing, the method has the advantages that real-time performance is good, mirror image frequency does not need to be eliminated, the reader structure is remarkably simplified, and time sequence control is very simple.

The application designs a Coriolis mass flowmeter signal processing method based on orthogonal demodulation; an orthogonal demodulation method CH-QD based on correlation operation and Hilbert transform is proposed, first, autocorrelation operation is carried out on any one sensor signal, and the obtained autocorrelation signal is used as the same frequency cosine reference signal of the sensor signal; the autocorrelation signal is subjected to Hilbert transform, and the obtained Hilbert transform signal is used as the same frequency sine reference signal of the sensor signal; according to the same frequency and orthogonal relationship between the autocorrelation signal and the Hilbert transform signal thereof, the instantaneous frequency of the signal is calculated by complex number and trigonometric function operation; the two sensor signals are respectively subjected to sine and cosine reference signal demodulation, the center frequency of the signal is moved to the double frequency of the original frequency, and the low frequency component carrying the signal phase information is contained in the signal; the high frequency component is filtered out through a multi-stage low pass filter, and the low frequency component is retained; the low frequency component is used to extract the phase difference of the two signals, and the high-precision density, mass flow and other information of the fluid are provided.

The invention discloses a capacitance accelerometer structure resistance error compensation method based on alternating constant current driving, which is characterized in that the separation of a structure capacitance component and a structure resistance component is realized through a capacitance accelerometer compensation circuit. The system establishes a reference channel and a detection channel under the excitation of a constant current source, the detection channel outputs a comprehensive response containing capacitance and resistance, two paths of signals are input into a digital processing unit through a compensation circuit and an analog-to-digital conversion module, and in-phase and orthogonal components are obtained through orthogonal demodulation. Through channel cooperative processing, capacitive components (real acceleration signals) and resistive components (loss and error sources) can be effectively distinguished, and errors introduced by the resistive components are filtered out. According to the method, the influence of resistance components on the capacitance detection precision is avoided, and high-precision capture of micro capacitance change is realized under a fixed amplitude condition, so that the sensitivity, the stability and the signal-to-noise ratio of the capacitance accelerometer are remarkably improved.