114results about How to "Suppress high frequency noise" patented technology

A dust collection unit for a vacuum cleaner includes a first filtering chamber filtering relatively large foreign objects, a second filtering chamber filtering relatively small foreign objects when air exhausted from the first filtering chamber is introduced into the second filtering chamber, an exhaust member disposed above the filtering chambers to guide airflow, a storing chamber disposed under the filtering chambers to store the foreign objects filtered in the filtering chambers, a sealing member sealing bottoms of the filtering chambers, and a rectifying unit formed on an exhaust side of the second filtering chamber to rectify airflow, thereby reducing noise generated by the airflow.

A electrical connector structure includes ground terminals formed in two rows, which are fixed into two bases respectively, in which each of the ground terminals includes a contact portion, a soldering portion and a main body is connected to the contact portion and the soldering portion, and each main body is fixed into the bases, and each soldering portion extends out of the bases; and a ground member including two ground plates, in which the ground plates covering surfaces of the bases, respectively, and a surface of each ground plate has a plurality of contact arms protruding, the contact arms are electrically contacted to the ground terminals, respectively, in which two ends of each contact arm contact the ground plates, respectively.

The invention relates to a system for measuring a physical variable using a plurality of measuring sensors (20). Said system is characterized in that an inverting measuring signal amplifier (17; 17.1, 17.2) is connected downstream of every measuring sensor (20), one output of a sensor (20) each being connected to an inverting input of the measuring signal amplifier (17; 17.1, 17.2) connected downstream of the measuring sensor (20).

The invention provides a blasting vibration predicting method, which comprises the following steps of: firstly, determining a reference blasting hole and a plurality of vibration measuring points, and placing vibration meters on each vibration measuring point; blasting the reference blasting hole to obtain blasting vibration waveforms having different distance points; and finally, executing a blasting vibration waveform predicting process. In the prediction process, actual blasting vibration test data is obtained firstly, the blasting vibration waveforms and migration stacked delay time of each blast hole on a predicting target point are then calculated according to distance from the predicting target point to the each blast hole and the reference blasting hole, and the vibration waveform of the predicting target point can be obtained based on a vibration wave stacking principle. A blasting vibration predicting result which is obtained by adoption of the method really shows an influence of a topographic condition of a field on blasting vibration, and the integral vibration waveform of the predicting target point can be obtained; a predicted vibration velocity peak value of waveform particles is quite approximate to an actually-measured vibration velocity peak value, and a time difference between the predicted vibration velocity peak value and the actually-measured vibration velocity peak value is also quite small; and an analysis result is accurate and reliable, so that adjustment of a blasting scheme can be better guided.

The invention discloses a microseismic signal noise reduction filtering method based on a VMD and a wavelet packet and belongs to the signal processing technology field. In the invention, a mode of combining the VMD and the wavelet packet is adopted; adaptivity of a VMD decomposition method and characteristics of a high mathematical theory basis, high frequency noise suppression and the like in the algorithm are used; and the wavelet packet has the characteristics of carrying out multilevel division on a frequency band, further decomposing a high frequency portion which is not subdivided in multiresolution analysis, and adaptively selecting a frequency band according to a characteristic of an analyzed signal so that a time frequency resolution is increased. In the invention, based on a condition of maintaining randomness, non-stationary performance and a burst transient characteristic of a microseismic signal, the microseismic signal is filtered. The algorithm is simple and easy and an effect is ideal. Effective noise reduction filtering can be performed on a mine noisy microseismic signal. And a good technical value and an application prospect are possessed.

The invention discloses a five-phase inverter random SVPWM modulation method, and belongs to the technical field of multi-phase inverter drive control. In every sampling cycle, the sampling cycle is kept constant, a PWM pulse is delayed randomly, to achieve random change of a switch cycle, at the same time, two vector action time obtained through an NFV-SVPWM algorithm are randomly allocated, and double-random of switch frequency and zero vector action time is achieved. According to the five-phase random SVPWM modulation method, on the condition of not influencing low frequency-band harmonic performance, the amplitude of higher harmonic is drastically lowered, harmonic originally concentrated on the switch frequency and around the integral multiple switch frequency is dispersed into a wider frequency spectrum range, thus a more consecutive and even frequency spectrum is obtained, electromagnetic interference and high frequency noise are effectively inhibited, and the electromagnetic compatibility of the system is improved.

The invention discloses a target location extraction method applicable to through-the-wall radar imaging, belongs to the technical field of image processing, and particularly relates to through-the-wall radar imaging techniques. According to an image formed by a back wave of through-the-wall radar, firstly, high-frequency noisy points in the image are inhibited through a two-dimensional low pass filter, then, a plurality of detection thresholds with reasonable layouts are adopted, binaryzation detection is carried out on the target image, then, connected domains in the image after the detection are searched and used as possible target areas, the connected domains under the various thresholds are classified according to target subordinating relations, finally, occurrence numbers of the corresponding connected domains of various targets are arrayed, the corresponding connected domains with large numbers are selected, and statistical averages of all pixel unit locations in the connected domains are used as target location coordinates. According to the target location extraction method applicable to the through-the-wall radar imaging, accurate location coordinates of a plurality of targets comprising adjacent targets and dim targets can be steadily extracted in the target image with a low through-the-wall signal to clutter ratio and a low through-the-wall signal to noise ratio, and accurate target location based on the through-the-wall radar imaging is achieved.

The invention discloses a loop circuit compensating circuit used for a Buck converter, and belongs to the technical field of electronics. The loop circuit compensating circuit used for the Buck converter comprises a leading phase compensating circuit and a full-differential low-pass filter circuit. The leading phase compensating circuit generates a zero point and two high-frequency poles to provide leading phase compensating; the full-differential low-pass filter circuit provides a pole and high lower-frequency gain; the output voltage of the leading phase compensating circuit and the output voltage of the full-differential low-pass filter circuit are added in a linear mode to acquire a voltage signal required by III-type compensating; because the high lower-frequency gain and two lower-frequency zero points are acquired, the defects that lower-frequency gain is low and steady-state errors are large in leading phase compensating are overcome. According to the loop circuit compensating circuit used for the Buck converter, because full-differential input and output structures are adopted in the leading phase compensating circuit and the low-pass filter circuit respectively, power supply rejection ratio (PSRR) is increased, the crosstalk problem among DC-DC converters in all paths of a PMU can be effectively solved.

The invention discloses a circuit board for a low-noise mobile phone and a method for reducing noise of a mobile phone system. A differential wiring mode is taken as a wiring mode of an audio signal wire of an audio module of the circuit board; the wiring mode is strong in anti-jamming capability; magnetic beads are serially connected to an input end and an output end of the audio module; the magnetic beads are specially used for restraining high-frequency noise and peak interference on a signal wire and a power line, have a capability of absorbing a static pulse and are capable of excellently reducing related noise; the output end of the audio module is connected to a related capacitor; and the capacitor can be used for efficiently filtering noise and restraining coupling interference between the capacitor and the output end.

The invention relates to a design method for a linear active-disturbance-rejection controller based on a prediction tracking differentiator, and the method comprises the following steps: a, designingthe prediction tracking differentiator, and performing the filtering of an obtained state signal through the prediction tracking differentiator to obtain a filter value; b, obtaining an extension state of the system through an extension state observer based on the filter value; c, correcting a PD control law through the extension state to obtain the linear active-disturbance-rejection controller.The method provided by the invention can inhibit the impact on the closed-loop characteristics of a system from the noise pollution, can effectively inhibit the phase delay phenomenon caused by the filtering, solves a problem of noise pollution amplification caused by a high-gain observer, and improves the robustness of a controller. The method improves the robustness of the active-disturbance-rejection controller to the high-frequency noise, and has the engineering practicality.

The invention discloses a high-speed fully-differential noise reduction device for CMOS optical receivers. The noise reduction device comprises a low-noise trans-impedance amplifier which is used for converting a current signal output by a photoelectric detector into a voltage signal and preliminarily amplifying the voltage signal and has low equivalent input noise current, a single-ended to differential circuit which is used for realizing conversion from single-ended to differential output, increasing the circuit bandwidth, amplifying the voltage signal, effectively reducing equivalent input noise current introduced by a back-end circuit and eliminating common-mode noise introduced by a power supply and the like, a two-stage three-order differential limiting amplifier which adopts a staggered active feedback and capacitance degeneration circuit and is used for amplifying the voltage signal to a voltage level needed for a digital processing unit, and an output buffer stage which is used for converting an output differential voltage signal into a single-ended output voltage signal. On the premise of keeping the overall gain and bandwidth of the circuit, the introduced noise is reduced, and the sensitivity of optical receivers is improved.