2399 results about "Square waveform" patented technology

The invention belongs to the technical field of permanent magnet synchronous motor position-sensorless control, and discloses a surface-mounted permanent magnet synchronous motor full-speed-domain position-sensorless control method and system. In a zero-low-speed area, a high-frequency square wave voltage injection method is adopted for motor rotor position identification, a simplified signal processing mode is adopted, use of a filter is omitted, and position estimation precision is improved; the improved sliding mode observer is adopted to identify the position of the motor rotor in a medium-high speed domain, and aiming at the problems of buffeting and phase delay of a traditional sliding mode observer, a piecewise square change switching function is adopted to replace a sign function to reduce system buffeting, and a synchronous reference system filter is adopted to replace a low-pass filter to reduce system buffeting. The problems of phase delay and amplitude attenuation caused by back electromotive force are avoided; and an improved weighted switching method with continuous and smooth proportionality coefficients is adopted in a switching speed domain to realize stable switching of the rotating speed. The method has the advantages of being capable of accurately estimating the motor rotating speed and the rotor position in the full-speed domain, fast in dynamic response and good in estimation precision.

Provided in the present application are a balanced charging method and apparatus for a battery pack, and a computer program product. Charging current control consists of two stages, i.e., a "pulse square-wave excitation" stage and a "multi-stage current-reduction charging" stage. During the pulse square-wave excitation stage, the parameter identification of an equivalent circuit model and the joint estimation of state variables are realized, thereby providing reliable battery parameters for a subsequent balancing process. During the multi-stage current-reduction charging stage, a flyback converter is used to control a balanced current of each battery cell, and the battery cells remain in a charging state throughout a balancing process, thereby effectively mitigating the impact of a hysteresis voltage.

The invention provides a repair circuit, a display panel and display equipment. The repairing circuit comprises a dedelay unit, an input end of which is connected with a grid electrode to-be-repaired signal and an output end of which is electrically connected with a first node; the input end of the shaping unit is electrically connected to the first node, and the output end is electrically connected to the second node; the input end of the inverting unit is electrically connected to the second node, and the output end is electrically connected to the third node. The de-delay unit is used for processing the grid signal to be repaired according to the clock signal and outputting a de-delay signal, so that the falling edge of the de-delay signal is consistent with the falling edge of the clock signal; the shaping unit is used for processing the rising edge waveform of the dedelayed signal and outputting a square wave signal opposite to the dedelayed signal in phase; and the inverting unit is used for performing inverting processing on the square wave signal and outputting a grid electrode repairing signal. The repairing circuit can effectively repair abnormal grid signals in the display panel, and the product yield is improved.

The invention discloses an arc fault detection method and device based on voltage time difference variation, and belongs to the technical field of low-voltage power distribution network fault protection, and the method comprises the steps: enabling an arc fault point to be equivalent to an arc voltage source, and employing an arc voltage change rate and an arc voltage effective value, establishing detection feature description of a fault waveform generated by the arc voltage source, wherein the fault waveform presents a square-wave-like waveform; sampling adjacent cyclic wave voltages of a load side monitoring point, performing feature identification on the tail end voltage difference between adjacent cyclic waves based on detection features, and identifying a first fault waveform; and after the first fault waveform occurs, performing continuous identification counting on the arc faults, realizing identification of the continuous arc faults by using the difference between the non-fault waveform before the fault occurs and the waveform to be identified, and confirming the occurrence of the arc faults. The detection method is good in reliability, clear in physical significance, high in detection sensitivity, not affected by line parameters, capable of achieving detection only through a single monitoring point and lower in cost.

The invention relates to a color electronic paper energy-saving driving design method and system based on optimized square wave driving, and belongs to the technical field of electronic paper display. The method comprises the following steps: firstly, based on a displacement time relation model of charged particles in the color electronic paper microcapsule, determining an optimal driving voltage interval of the particles, and generating a square wave driving waveform library; secondly, the environment temperature is monitored in real time, and square wave driving waveform parameters are dynamically adjusted; thirdly, analyzing statistical characteristics of the input image, dividing content complexity and distributing driving voltage grades; and finally, identifying an image change area through a frame difference algorithm, and performing local refreshing or global refreshing to realize image display. According to the color electronic paper energy-saving driving design method and system based on optimized square wave driving, an efficient and cooperative temperature compensation mechanism and a dynamic voltage adjusting strategy are combined, the display quality is maintained, meanwhile, the driving energy consumption of the color electronic paper is effectively reduced, and it is ensured that the color electronic paper is kept effective and stable in various temperature environments.

The invention discloses a new energy automobile wireless power supply soft switching control system based on a segmentation strategy, and particularly relates to the technical field of new energy automobile wireless power supply, and the control system comprises a resonance current zero-cross detection module which detects a resonance current output square wave signal of a resonance network in real time; the segmented control decision module is used for selecting a strong control strategy or a weak control strategy according to a comparison result of the smoothed frequency difference value and a preset threshold value; the segmented control execution module is used for adjusting the inverter driving frequency by adopting a corresponding control algorithm according to the output of the segmented control decision module; according to the new energy automobile wireless power supply soft switching control system based on the segmentation strategy, the segmentation control logic and the model and algorithm of the special module are designed, so that the driving frequency of the new energy automobile is adjusted, and the driving frequency of the new energy automobile is adjusted to be within the preset frequency locking range. And wide-range frequency locking, rapid dynamic correction and high-precision steady-state control are realized.

The invention relates to the technical field of real-time kernel performance testing of special chips, in particular to a special chip real-time performance evaluation method based on an FPGA (Field Programmable Gate Array), which comprises the following steps: (1) aiming at a real-time system on an ASIC (Application Specific Integrated Circuit) chip, setting an external interrupt source and an interrupt service program through a hardware interrupt controller; (2) two tasks with the same priority are created, scheduling of the tasks is achieved through time slice rotation, and a real dynamic load scene is simulated; (3) configuring an external FPGA (Field Programmable Gate Array) to generate a square wave signal to trigger external interruption of the ASIC chip, receiving a feedback signal, and connecting the FPGA and the GPIO through an external physical connecting line to form a hardware interruption triggering-response closed loop; and (4) realizing nanosecond timestamp capture through a counter built in the FPGA, acquiring time delay data, calculating interrupt response time, and transmitting the time delay data to a PC (Personal Computer) through a UART (Universal Asynchronous Receiver / Transmitter) to calculate a maximum value, a minimum value, an average value and a data jitter range of test data. The method can effectively solve the problem that the traditional internal closed-loop test cannot reflect the real interruption randomness and the dynamic load.

The invention provides an implementation method of a novel low-distortion digital modulation direct drive power amplifier device, and relates to the field of plasma generation radio frequency power supplies, the method realizes acquisition of modulation waveform signals through a delta-sigma oversampling technology, and realizes further improvement of the sampling rate of the modulation waveform signals through a PDM pulse distribution unit interpolation filter. The exciter can generate multi-phase PDM modulation waveform pulses and carrier wave driving pulses, and directly drives the power amplifier module to complete carrier wave generation and waveform modulation. Multi-phase PDM modulation can achieve a better modulation waveform THD (Total Harmonic Distortion) index, it is ensured that a modulation waveform signal is basically subjected to distortion-free recovery, but in order to reduce the complexity of a system and give consideration to the modulation waveform total harmonic distortion index, the multi-phase PDM modulation is generally controlled within 12 phases. In addition, a modulation waveform signal is divided into a plurality of equal-amplitude PDM square wave signals by a multi-phase PDM modulation and superposition technology, so that the power amplifier works in an on-off state, and the efficiency of the power amplifier is improved.

The invention relates to the technical field of high-voltage power supply wiring terminal monitoring, in particular to a safety state monitoring method and system for a high-voltage power supply wiring terminal, and the method comprises the steps: obtaining the current data of a connection line of the high-voltage power supply wiring terminal and the temperature data of the wiring terminal; dividing a rising process, a falling process and a constant process to obtain a square wave impact current and a non-square wave impact current; the steep degree of current change in the rising and falling process and the deviation degree of current data in the constant process are analyzed, a current impact coefficient is obtained, a current impact temperature change consistency coefficient is constructed, a synchronous abnormal coefficient of each time period is obtained, and the state of the high-voltage power supply wiring terminal is monitored. According to the invention, the accuracy of monitoring the safety state of the high-voltage power supply wiring terminal is improved.

The embodiment of the invention provides an excitation signal generation method and system and a digital eddy current sensor, and the method comprises the steps: outputting a square wave signal through a pulse width modulation assembly of a microcontroller unit, and enabling the frequency and resolution of the square wave signal to be adaptive to eddy current probes with different inductance values; inputting the square wave signal into a low-pass filter for filtering, and setting the cut-off frequency of the low-pass filter, the suppression times of higher harmonics and the attenuation slope so as to output a sine wave signal with a target total harmonic distortion range; the amplitude of the sine wave signal is collected in real time, and the pulse width modulation duty ratio and the passband gain of a low-pass filter are dynamically adjusted in combination with a digital control algorithm, so that the sine wave signal is subjected to self-adaptive adjustment and correction and is output; and taking the sine wave signal as an excitation source of an eddy current probe, and driving the eddy current probe to carry out nondestructive testing. According to the invention, the excitation signal which gives consideration to high-frequency signal generation, deep harmonic suppression and digital adaptive adjustment can be generated.

The invention provides a closed-loop electrical stimulation system and a control method.The closed-loop electrical stimulation system comprises an equipment main control system, a trigger and control system, an electrical stimulation system and an electrical signal collection system.The equipment main control system is used for receiving square wave trigger signals from external equipment and processing the square wave trigger signals through electrical stimulation work instructions; the electrical stimulation work instruction and the processed square wave trigger signal are transmitted to the trigger and control system; the trigger and control system is used for receiving the square wave trigger signal and the electrical stimulation work instruction, and responding to the square wave trigger signal by using a square wave generator included in the trigger and control system to generate a square wave signal; the electrical stimulation system comprises a plurality of signal channels and is used for generating a plurality of paths of electrical stimulation signal outputs; the electric signal acquisition system comprises a plurality of signal channels and is used for acquiring the current on the tested body bearing the multi-path electric stimulation signal output to obtain multi-path electric signal acquisition output, and the multi-path electric signal acquisition output is used for adjusting the parameters of the multi-path electric stimulation signal output.

The invention relates to a high-adaptability fused salt heat storage system in-situ monitoring method, which is characterized in that current and potential signals correspond to the concentration of impurity ions in fused salt through an electrochemical analysis method, and the current value of a characteristic peak corresponds to the concentration of impurities in the fused salt, so that sampling and chemical analysis are not needed; according to the method, the real-time concentration of the impurities can be obtained only by acquiring the characteristic peak current value through electrochemical scanning, the fused salt component analysis process is greatly simplified, the real-time monitoring of the ion concentration through the square wave voltammetry is an automatic and continuous process, and compared with a traditional analysis method, the method has the advantages of being high in sensitivity and analysis speed and suitable for popularization and application. And analyzable response can be generated to tiny concentration change. According to the invention, in-situ and continuous measurement of the concentration of the marker impurities in the molten salt can be realized, and timely and accurate feedback can be provided for changes of components and heat storage performance of the molten salt.

The invention provides a transformer partial discharge positioning method and device based on bushing CT acquisition. The method comprises the following steps: acquiring a high-frequency partial discharge pulse signal of a current transformer at a transformer bushing; background noise of the pulse signal is removed, amplitude correction is carried out, and a corrected pulse signal is obtained; judging whether the partial discharge belongs to external interference or internal partial discharge based on the polarity distribution rule of the corrected pulse signal; if the interference is external interference, comparing the amplitudes of the correction acquisition signals corresponding to the bushings, and taking the position corresponding to the current transformer with the maximum amplitude as an interference source injection position; if partial discharge occurs in the transformer, calculating the distance proportion from the partial discharge position to the head end of the winding according to the attenuation characteristic of the pulse signal propagating in the winding and the pre-injected calibration square wave signal so as to determine the discharge position. According to the method, the method for determining the partial discharge position of the transformer is simplified, external interference and internal partial discharge signals can be quickly identified, and misoperation of a protection device is avoided.

The utility model relates to an anti-pinch detection circuit and a motor device, the anti-pinch detection circuit comprises a sampling circuit, a differential amplification circuit, a ripple signal conversion circuit, a low pass filter circuit and a controller, the sampling circuit samples a ripple current signal of a vehicle window motor to obtain a corresponding voltage sampling signal, and the voltage sampling signal is sent to the differential amplification circuit; the differential amplification circuit carries out differential amplification on the voltage sampling signal to obtain a voltage amplification signal, the voltage amplification signal is divided into two paths, one path is converted into square wave signals through the ripple signal conversion circuit, the controller determines the position of a car window according to the number of the square wave signals, and the other path is subjected to low-pass filtering through the low-pass filtering circuit to obtain the voltage amplification signal. If the position of the car window is located in the preset anti-pinch area, the controller determines whether the car window is locked or blocked or not according to the amplitude of the low-frequency ripple signal. The anti-pinch detection circuit adopts two-path detection, so that the influence of environment or other factors on the ripple current signal is avoided, further anti-pinch misjudgment is avoided, and the anti-pinch detection accuracy is improved.

The invention discloses an eddy current displacement sensor sine constant current source excitation method, and belongs to the technical field of sensor measurement and control. The method comprises the following steps: S1, generating positive and negative symmetric reference voltages through a reference voltage source circuit; s2, outputting a square wave control signal with adjustable frequency by the control chip, and driving a switching circuit to generate a square wave taking the positive and negative reference voltage as a level; s3, processing the square wave through a filter circuit to obtain a standard sine wave voltage signal; and S4, converting the sine voltage signal into sine constant current source excitation through a Howland current source circuit, and outputting the sine constant current source excitation to a sensor probe coil. According to the invention, through combination of digital control and analog conversion, the circuit structure is simplified, the cost is significantly reduced, and convenient adjustment of the output frequency and high stability and precision of the output current are realized at the same time.

The invention provides a method for setting a relationship between conduction voltage drop and junction temperature of a power device in a large-current on-off state, and the method enables a tested device to work in the on-off state, and the large current flowing through the device is a square wave current with a fixed amplitude and a fixed duty ratio. The operation junction temperature and the reference point temperature are set by controlling the operation condition of the circuit and the temperature of the radiator; after the device runs to a thermal steady state, measuring the conduction voltage drop and the reference point temperature of the device, then cutting off a large current, and injecting a constant small current into the measured device to measure the junction temperature of the measured device; the equivalent temperature of the packaging material is represented by the reference point temperature, and a linear relation among the conduction voltage drop, the reference point temperature and the junction temperature under the large current is fitted. According to the invention, the self-heating and external heating conditions of the whole timer can be flexibly controlled, and the influence of the temperature of the packaging material on the conduction voltage drop is considered, so that the accuracy of predicting the junction temperature by using the conduction voltage drop under large current is improved.

The invention discloses a current transformer residual magnetism detection method based on a high-frequency square wave, and the method comprises the steps: controlling a magnetism detection voltage unit to output a high-frequency square wave through an upper computer, and achieving the bidirectional depth saturation of a current transformer in a single magnetism detection period; the data acquisition unit detects the secondary side current of the current transformer and transmits current data to the upper computer; the upper computer processes the collected current signal, and obtains the size and direction of a second harmonic by using FFT (Fast Fourier Transform); and according to the transfer function of the secondary harmonic and the transformer residual magnetism, calculating to obtain the magnitude and direction of the transformer residual magnetism. According to the method, bidirectional deep symmetric saturation of the iron core in a single period is achieved, harmonic signals exist in a secondary side loop, the harmonic signals are extracted and analyzed, and the residual magnetism condition of the iron core can be obtained. According to the invention, high residual magnetism detection precision can be realized, the residual magnetism direction can be discriminated, the residual magnetism condition can be obtained in a short time, and the method has the characteristic of high efficiency.

According to an embodiment, an LLC resonant converter includes a switching bridge having a plurality of power switches. The switching bridge is configured to receive a DC voltage input and generate a square waveform based on a pulse-modulated frequency (PFM) signal at the switching bridge. The LLC resonant converter further includes a resonant tank circuit coupled to the switching bridge. The resonant tank circuit includes a resonant inductor. The resonant tank circuit is excited in response to receiving the square waveform. The PFM signal is adjusted such that an elapsed time between a rising edge of a Drain-Source Voltage of a power switch and a zero-crossing point of current flowing through the resonant inductor falls within a predetermined range corresponding to the resonant tank circuit operating at its resonant frequency.

The embodiment of the invention discloses an aero-engine rotating speed measuring device which is characterized by comprising a tachogenerator module, a hardware conditioning module, a high-speed A / D conversion module, a data picking and buffering module, a digital signal processing module, a rotating speed measuring module, a power supply module, an operation control module and a communication module which are connected in sequence. The tachogenerator module converts an acquired engine rotating speed signal into a sine-wave-like alternating-current voltage signal of which the frequency and the amplitude are positively correlated with the rotating speed. The hardware conditioning module is used for conditioning the sine-like signal with a relatively wide amplitude range into a signal meeting the amplitude range requirement of the high-speed A / D conversion module; the high-speed A / D conversion module performs high-speed sampling on the conditioned sinusoidal-like signal and converts the conditioned sinusoidal-like signal into a digital signal; the data picking and buffering module is used for picking and buffering the digital signals subjected to A / D conversion; the digital signal processing module is used for converting the digital signal into a digital square wave signal; the rotating speed measuring module is used for monitoring the frequency of the digital square wave signal and calculating the rotating speed of the engine through the frequency; and the communication module is used for uploading the engine rotating speed measurement result to the flight control computer. The technical scheme of the invention solves the problem.

The invention belongs to the induction type oil abrasive dust sensor technology, and particularly discloses a non-ferromagnetic oil abrasive dust high signal-to-noise ratio induction type detection method and system, and the method comprises the following steps: a microcontroller carries out the control, and sends an instruction to two waveform generation chips through the microcontroller; dual-signal generation: generating two waveform and phase-adjustable periodic signals based on two waveform generation chips; the square wave frequency mixing is used for introducing a square wave as a parameter control signal to carry out frequency mixing operation; and frequency mixing difference adjustment: the optimal signal-to-noise ratio of different non-ferromagnetic chip signals is obtained by adjusting the frequency mixing difference. The frequency mixing difference between the induction signal and the reference signal can be accurately controlled, especially for non-ferromagnetic chips, different frequency mixing differences are adopted to improve the chip signal-to-noise ratio, meanwhile, square waves are introduced to serve as the reference signal to improve the chip signal amplitude, the phase shift process is simplified, the stability of the circuit is improved, and reliable data are provided for subsequent chip signals.

The invention discloses a laser radar transmitting circuit with pulse width compensation and a control method thereof. The circuit comprises an optical pulse transmitting circuit and a pulse width sampling control signal feedback circuit. The method comprises the following steps: generating a starting pulse signal and exciting an optical pulse transmitting circuit to output a laser pulse signal according to the starting pulse signal; comparing the laser pulse signal with a reference voltage, and outputting a square wave pulse signal; capturing the square wave pulse signal to obtain time interval data; carrying out calculation according to the time interval data to obtain the pulse width of the laser pulse current and carrying out output voltage regulation processing to obtain a signal feedback quantity; and performing feedback regulation on the output voltage of the optical pulse transmitting circuit according to the signal feedback quantity. According to the embodiment of the invention, pulse width acquisition and adjustment of the optical pulse current can be realized, so that the pulse width stability of the optical pulse current is improved. The laser radar transmitting circuit can be widely applied to the technical field of laser radar transmitting circuits.

The invention provides an automatic frequency locking circuit based on a time-to-voltage converter and a phase-locked loop, and relates to the technical field of phase-locked loops, a first frequency-halving unit and a second frequency-halving unit respectively carry out frequency-halving processing on a reference signal and a frequency division signal of a current comparison period to obtain a first square wave signal and a second square wave signal; the first square wave signal and the second square wave signal are transmitted to the time-to-voltage converter; the time voltage converter comprises a phase generation unit, a first charge pump and a second charge pump, the phase generation unit generates an enable signal according to the first square wave signal and the second square wave signal, and the first charge pump and the second charge pump respond to control of the enable signal and collect single pulse signals from the first square wave signal and the second square wave signal respectively so as to supply power to the input end of the comparator; the comparator compares power supply voltages of the two input ends to achieve frequency comparison of the reference signal and the frequency division signal. And selection in a plurality of phase signals is not needed, and required digital circuit modules are reduced, so that the delay of the reference signal and the frequency division signal in the conversion process is reduced.

The invention belongs to the technical field of sensor signal amplification, and discloses a vibration cylinder pressure sensor signal amplification circuit and a vibration cylinder pressure sensor.The vibration cylinder pressure sensor signal amplification circuit comprises a filter circuit, a gain adjusting circuit, a phase adjusting circuit, an amplitude limiting circuit, a frequency detection circuit and a temperature detection circuit; amplitude adjustment of a certain gain is achieved through a gain adjusting circuit, a gain amplification signal VB is obtained and input to a phase adjusting circuit and a frequency detection circuit, the phase adjusting circuit outputs a square wave signal VC and inputs the square wave signal VC to an amplitude limiting circuit, and the amplitude limiting circuit outputs an amplitude limiting square wave signal VD and loads the amplitude limiting square wave signal VD to a vibration cylinder; a gain amplification signal VB output by the gain adjusting circuit passes through the frequency detection circuit, a square wave frequency signal VO is output, a closed-loop control system is formed to achieve driving and detection of the resonance cylinder pressure sensor, and the actual frequency of the vibration cylinder body depends on the sensed pressure.

The invention discloses a low-power-consumption winch sensor based on a tunneling magnetoresistance effect. The low-power-consumption winch sensor comprises a measurement module, a signal conversion unit, a shell, a mandrel, a magnetic rotary disc and a detection assembly. The magnetic turntable and the mandrel are connected and rotate synchronously, the detection assembly comprises a TMR sensing element and N magnets, and the magnetic turntable is provided with mounting blind holes for embedding the magnets; the TMR sensing element is arranged on the shell and comprises a mounting plate and two sensing units, the magnetic domain directions of the two sensing units are perpendicular to the rotation axis, magnetic resistance signals of the two sensing units are converted through the signal conversion unit and input into the measuring module, the horizontal distance between the centers of the two sensing units and the magnet and the rotation axis is R, and the center distance L of the two sensing units is smaller than R * sin (180 degrees / N); the sensor is based on the TMR tunneling magnetoresistance effect, is high in detection sensitivity and low in energy consumption, outputs square wave signals with phase differences, can be used for a measurement module to accurately analyze and calculate the rotating speed and the rotating direction of a winch roller, is simple in overall structure, small in radial size and easy to install, and the installation precision is controlled.

The invention discloses a transformer-based analog quantity isolation transmission device and method. The transformer-based analog quantity isolation transmission device comprises an analog quantity input module, a symmetric square wave transformation module, a transformer module, a rectifier module and an analog quantity output module, the analog quantity input module is used for inputting analog quantity; the symmetrical square wave conversion module is used for converting the input analog quantity into symmetrical alternating-current square waves; the transformer module is used for transmitting the converted alternating-current square wave from the primary side of a transformer to the secondary side of the transformer, and isolation of analog quantity is achieved through the transformer; the rectifier module is used for rectifying the alternating-current square wave isolated by the transformer to realize analog quantity reduction; and the analog quantity output module is used for outputting analog quantity. According to the invention, the analog quantity can be directly transmitted based on the transformer.

The invention discloses a high-voltage direct-current line EM lightning arrester valve plate shunting non-uniformity test system and method, and belongs to the technical field of lightning arrester performance test.The method comprises the steps that S1, a high-voltage direct-current power transmission system simulation model is established, and the discharge current of an EM lightning arrester under the severe working condition of single-pole line short circuit is evaluated based on the high-voltage direct-current power transmission system simulation model; adopting square-wave pulse approximate discharge current, and determining the total amplitude and square-wave pulse width of long-wave discharge current of the EM lightning arrester; s2, applying the square wave pulse to the tested EM lightning arrester resistor discs through a shock wave test platform, and testing the current magnitude and the total current of each resistor disc of the EM lightning arrester under the working condition; the total amplitude and the square wave pulse width of the preset square wave pulse are the same as the total amplitude and the square wave pulse width of the long wave of the discharge current of the EM arrester; and S3, according to the current of each resistor disc and the total current, calculating a current non-uniform coefficient and the current range of the resistor discs. According to the invention, the current distribution non-uniformity of the multi-column parallel lightning arrester can be tested and evaluated more reasonably and comprehensively.

The invention relates to a test method and device for examining broadband measurement performance of a capacitor voltage transformer. The method comprises the following steps: frequency response test: acquiring sine wave voltage signals and first output voltage signals output by the capacitor voltage transformer to be tested for multiple times; processing the signals at different frequency points to obtain gain, phase characteristics and steady-state response capability at each frequency point; a square wave signal transmission test: collecting a square wave voltage signal and a second output voltage signal output by the capacitor voltage transformer to be tested; carrying out signal time-frequency domain analysis to obtain rapid voltage change transient response capability and broadband measurement accuracy; an operation / lightning impulse transmission test: collecting a transient operation / lightning impulse wave voltage signal and a third output voltage signal output by the capacitor voltage transformer to be tested; signal processing is carried out, and the response capability and high-frequency measurement accuracy of the transient high-frequency voltage signal are obtained; and the broadband measurement performance is obtained. Compared with the prior art, the method has the advantages of comprehensively examining the broadband measurement performance of the capacitor voltage transformer and the like.

The invention discloses an active pen and touch screen interaction system resistant to common-mode interference and a signal demodulation method. The system comprises a signal receiving terminal and a signal transmitting terminal. The signal transmitting terminal modulates data to be transmitted by adopting a differential binary phase shift keying modulation method, and transmits a generated modulation signal to the signal receiving terminal; the analog front-end receiving module is coupled with the signal transmitting terminal, receives the modulation signal and outputs a digital square wave signal after fidelity extraction processing; and the digital demodulation processing module performs differential coherent digital demodulation on the digital square wave signal based on the prior characteristics of the modulation signal, inhibits residual noise and recovers data to be sent. The analog front end focuses strong common-mode noise suppression and analog filtering, the digital demodulation algorithm performs secondary digital purification by using signal time sequence characteristics, and the two constructs an efficient anti-interference pipeline. Meanwhile, the regular square wave signals can be directly processed through differential coherent demodulation, and the requirements for performance and power consumption of a rear-end processor are lowered.

The invention discloses an ophthalmic high-frequency magnetic field stimulator and an eye nursing method. The ophthalmic high-frequency magnetic field stimulator comprises a controller and a head ring detachably connected with the controller through a cable, the head ring comprises an adjustable head ring telescopic belt and at least two magnetic stimulation actuators, and each magnetic stimulation actuator comprises an iron core formed by overlapping multiple layers of sheet metal and a conductive coil wound outside the iron core. The controller comprises a power supply module connected with a conductive coil of the magnetic stimulation actuator, the power supply module comprises a power supply for supplying direct current, the direct current is supplied through the power supply of the power supply module, a magnetic field is generated after the conductive coil is electrified, the waveform of current output by the controller is square wave, and the frequency is 1k-200kHz.

The invention provides a flow measurement method of an external clamping type ultrasonic flowmeter using a synchronous acquisition mode, which comprises the following steps of: simultaneously driving an upstream transducer and a downstream transducer to transmit signals by current signals from a function generator, and recording received signals of the transducers on the same time window; after ultrasonic signals synchronously collected by the transducer are subjected to time domain and frequency domain analysis, filtering processing and amplification processing, a function generator is used for converting and outputting square waves, and then the square waves are output to different channels after being digitalized through a multi-channel oscilloscope; by analyzing the digital square waves, ultrasonic forward and reverse flow propagation time and time difference are calculated, and then the flow is calculated by combining a time difference method measurement principle with measurement pipeline section parameters. According to the external clamping type ultrasonic flowmeter, an active synchronous acquisition mode is used, the two transducers are driven at the same time and receive signals, ultrasonic waves pass through fluid with the same temperature and flow profile, and therefore the time difference measurement deviation and the flow calculation error of the external clamping type ultrasonic flowmeter are reduced.