254results about How to "Reduce high frequency noise" patented technology

Glare is reduced by acquiring an input image with a camera having a lens and a sensor, in which a pin-hole mask is placed in close proximity to the sensor. The mask localizes the glare at readily identifiable pixels, which can then be filtered to produce a glare reduce output image.

In a method of imaging an object, for dental purposes, comprises:a) projecting a striped pattern on to the object to be imaged,b) recording the projected striped pattern as a basic image (Ri) with a camera, steps a) and b) being carried out at a number of different positions of the phase relationship of the striped pattern, andc) computing an image of the object from the plurality of mutually out-of-phrase basic camera images. Provision is made for suppression of periodic disturbances in that, in step c),c1) at least two groups of basic images (R1, R2, . . . , Rn; R2, R3, . . . , Rn+1) are formed from the basic camera images (R1, . . . , Rm),c2) a phase related image (Pj) of the object to be imaged (20) is computed from each group of basic images (R1, R2, . . . , Rn; R2, R3, . . . , Rn+1),c3) the computed phase related images (P1, P2) are averaged such that a phase related image (P) having a reduced amount of noise is formed, and thatc4) an image of the object is computed from the phase related image (P) having a reduced amount of noise.

A method of operating a metrology instrument includes generating relative motion between a probe and a sample at a scan frequency using an actuator. The method also includes detecting motion of the actuator using a position sensor that exhibits noise in the detected motion, and controlling the position of the actuator using a feedback loop and a feed forward algorithm. In this embodiment, the controlling step attenuates noise in the actuator position compared to noise exhibited by the position sensor over the scan bandwidth. Scan frequencies up to a third of the first scanner resonance frequency or greater than 300 Hz are possible.

An electric power steering apparatus includes a steering torque detector, a brushless motor PWM-driven with a three-phase alternating motor current, a target current setting section for setting a d-axis target current value and a q-axis target current value, motor current detectors for detecting motor current values supplied to the brushless motor, a three-phase AC / d-q coordinate transformation circuit, a first deviation calculation circuit for calculating a deviation of a current value of a q-axis detection signal from the q-axis target current value, a second deviation calculation circuit for calculating a deviation of a direct current value a d-axis detection current signal from the d-axis target current, a motor control section for controlling driving of the brushless motor through a vector control process on the basis of deviation signals outputted from the first and second deviation calculation circuits, and an attenuation device provided in a feedback transmission path of the q-axis detection current signal for attenuating a high frequency noise mixed in the q-axis detection current signal.

A charge pump for generating an input voltage for an operational amplifier includes a storage capacitor for storing a charge pump voltage and a flying capacitor configured to be charged during a first phase of operation and discharged during a second phase of operation. Discharging the flying capacitor charges the storage capacitor. A current source supplies the flying capacitor and a switching means switches current from the current source through the flying capacitor in a first direction during the first phase and in a second opposite direction during the second phase.

A rotor position detecting circuit includes a first position detecting circuit having a low-pass filter that shapes up phase voltage induced in a phase coil and a first comparator that compares the output voltage of the low-pass filter with a threshold level to form a first rotor position signal, and a second position detecting circuit having a second comparator that compares the phase voltage with a threshold voltage and a control unit that digitally processes the output voltage of the second comparator to form a second rotor position signal. The control unit corrects the first rotor position signal by the second rotor position signal to provide a final rotor position signal when the rotation speed of the brushless DC motor is in a measurable range.

The invention discloses a multi-parallel inverter motor speed regulating system and a control method of the multi-parallel inverter motor speed regulating system. The system is formed by connecting multiple inverter modules in parallel. The direct current sides of multiple inverter sub modules are directly connected with a direct current power supply with a direct current bus capacitor in parallel. The alternating current sides of the multiple inverter sub modules are connected with multiple sets of smoothing reactors respectively in series and then directly connected in parallel to drive an alternating current motor. By the adoption of the structure, modularization expansion of the motor speed regulating system is easily conducted, and the fault-tolerance performance of the motor speed regulating system is enhanced. By means of a random SVPWM method based on carrier phase shifting, switching frequency of parallel inverters is equivalently improved, switching subharmonic energy within narrow frequency bands is equalized, the harmonic performance of output currents of the parallel inverters is improved, and electromagnetic interference resistance of the motor speed regulating system is enhanced. By the adoption of a space vector synthetic technology for dynamically allocating SVPWM zero vectors, zero-sequence circulating currents between the parallel inverter modules are effectively eliminated, and normal operation of the system is guaranteed.

The invention discloses a headset communication method under a strong-noise environment and a headset. The method comprises: using earplugs to reduce medium and high frequency noises entering an ear canal, using an external connection cavity in parallel connection with the ear canal to divert medium and low frequency noises; using an internal microphone to pick up the sound in the ear canal and an environmental noise signal entering the ear canal, using an external microphone to pick up the environmental noise signal, and taking the external microphone signal as reference signals to eliminate the noise element in the internal microphone signal and remain the voice element to obtain transmitting terminal signals of the headset; using sound dynamic compression technology to cut down and compensate the signals picked up by the external microphone in terms of sound pressure level such that the sound pressure range is compressed to a range acceptable by human ears and the signals picked up by the external microphone and the receiving terminal signal received by the headset are broadcast together through a receiver of the headset. By means of the technical scheme of the present invention, the functions of protecting hearing, enhancing voice and monitoring a three-dimensional environment can be achieved comprehensively under strong-noise environments.

An error voltage Verr, being a difference between DC output voltage Vout and output reference voltage Vref, and an input voltage Vin are multiplied to produce first threshold voltage signal Vth1 in phase with and similar to input voltage Vin and proportional to Verr. Second threshold voltage signal Vth2 is produced from first threshold voltage signal Vth1. The input current is detected as a current detection signal Vi across a resistor 12, whether it is between the threshold value signals is detected by a current range detecting circuit, and accordingly, the timing of turning on or off switching device is controlled so that at least one of an duration on and an off duration of the switching device is limited to enhance a power factor. Unfixed off duration disperses a noise spectrum to prevent an increase in switching frequency, to reduce noise.

The invention provides an inverse Q filtering method for a seismic wave signal. The method comprises the following steps: extracting a quality factor Q value from the seismic wave signal collected from a seismic channel; performing time-frequency transformation on the collected seismic wave signal so as to acquire a seismic wave frequency spectrum shown in the specification, wherein tau is a travel-time and omega is an angular frequency; and performing inverse Q filtering on the seismic wave frequency spectrum by utilizing the following formula shown in the specification, so as to acquire the seismic wave frequency spectrum U (tau, omega) after inverse Q filtering, wherein gamma is equal to 1 / (phiQ); omega h is the highest frequency within the seismic bandwidth; sigma 2 is a stable factor; i is an imaginary part unit; tau' in exponential terms is an integration variable, and the value range of the integration variable is within an integrating range from omicron to tau; and the quality factor Q is related to the integration variable tau'. The high-frequency component is not pressed in the stabilizing treatment process in the inverse Q filtering method provided by the invention, so the inverse Q filtering method has the advantages that the resolution ratio is increased but the high-frequency noise is not increased, and the signal to noise ratio (SNR) is increased.

An electrical connector includes an insulating housing, a plurality of conductive terminals, a shielding plate and a ground element. The insulating housing has a base portion, and a tongue portion protruded frontward from a front surface of the base portion. The conductive terminals are received in the insulating housing, and front ends of the conductive terminals are exposed to the tongue portion. The shielding plate is received in the insulating housing. The ground element is for being connected between the shielding plate and ground. The ground element is received in the insulating housing. The ground element has a touch portion contacting the shielding plate.

CT imaging is enhanced by adaptively filtering x-ray attenuation data prior to image reconstruction. Detected x-ray projection data are adaptively and anisotropically filtered based on the locally estimated orientation of structures within the projection data from an object being imaged at a plurality of rotation positions. The detected x-ray data are uniformly low pass filtered to preserve the local mean values in the data, while the high pass filtering is controlled based on the estimated orientations. The resulting filtered data provide projection data with smoothing along the structures while maintaining sharpness along edges. Image noise and noise induced streak artifacts are reduced without increased blurring along edges in the reconstructed images. The enhanced image allows reduced x-ray dose while maintaining image quality.

The invention relates to a double-T-shaped framework elastic hinging flexible suspension direct driving radial steering frame, which comprises a steering frame framework, a shaft box device (4) and two permanent magnet direct driving motors (3), wherein the shaft box device (4) is used for positioning wheel pairs (5); the permanent magnet direct driving motor (3) is used for driving the wheel pairs (5); the steering frame framework is a double-T-shaped elastic hinging framework with the flexible function; each of the two permanent magnet direct driving motors (3) is arranged on a steering frame framework through a three-point type suspension mechanism, and respectively drives one wheel pair (5). Compared with the prior art, the double-T-shaped framework elastic hinging flexible suspension direct driving radial steering frame has the advantages that the flexible function of the steering frame is good; the adapting route twisting capability is high; the unsprung mass is light; the operation noise is low; the active radial function is realized, and the like.

A flat-panel display unit is provided which includes: a PDP 10; an aluminum chassis 2 that is attached to the PDP 10; an upper data driver substrate 6 and a signal processing substrate 7 that are attached to the aluminum chassis 2; and a flexible cable 8 that connects the substrates 6, 7 electrically. Between the substrates 6, 7, a pressing plate 9 fixes at least one part of the flexible cable 8, so that the space between the flexible cable 8 and the aluminum chassis 2 remains unchanged. Thereby, a stray capacitor can be stably formed using the insulating material of the flexible cable 8, and a high-frequency noise can be effectively reduced.

The invention discloses an eye fundus image quality evaluation method based on a human vision system, which comprises the following steps: selecting a part of eye fundus images in a data set as original data samples, preprocessing the original data samples, removing a background part, and extracting an interested region part; calculating a saliency map of the fundus image; training the convolutional neural network by using the fine-tuning deep neural network, and migrating network parameters of the natural image to the training of the medical image network; extracting features of the fundus image and saliency features in the saliency map, and carrying out feature fusion; and constructing a feature matrix of the sample for the fused features, training a support vector machine classifier byutilizing the feature matrix, and classifying the quality of the fundus image. Supervision information based on a convolutional neural network and non-supervision information based on a saliency map are fused, a fusion information training classifier is utilized to classify the image quality, and a transfer learning principle is utilized to improve the performance of the image quality classification by using a method of finely adjusting the deep convolutional neural network.

The invention discloses a riding mower with a noise reduction measure and hydraulic stepless speed change. The riding mower comprises a steerable front axle, a drivable rear axle with hydraulic stepless speed change, a frame with a double-protection lever, a mowing device with noise reduction, an engine with a noise elimination groove, a head housing with noise reduction, a noise elimination air filtering net, a saddle with noise reduction and a grass collection box with noise reduction, wherein the front axle is connected with two front wheels; the drivable rear axle is ocnencted with two rear wheels; the frame is arranged above the four wheels; the mowing device is arranged below the frame; the engine is arranged above the frame close to the front side; the saddle is arranged on the middle part above the frame close to the rear side; the grass collection box is arranged behind the mower; in addition, for personal protection of a riding operator, accessories such as earplugs, sound-proof cotton, ear muffs and a sound-proof helmet are arranged. The invention also introduces a heightening quadrilateral structure, diagrammatic design of a mowing part, a preferable thinking method and a comprehensive application method of the noise reduction measure to the entire mower.

A correlated double sampling circuit has a sampling capacitor equally divided into a plurality of portions. In the correlated double sampling circuit, an input signal is sampled at a plurality of sampling points and an averaging switch is closed to obtain an average value of a plurality of sampling values obtained by sampling. High frequency noise superimposed on the input signal is thus reduced and a difference between the average values of the plurality of sampling values obtained by sampling is output.

The invention discloses a device and a method for expanding speech bandwidth based on G.711.1. The method of the invention comprises the steps of: further compressing the high frequency speech code stream in a G.711.1 protocol, embedding the compressed data in the encoded code stream of narrow band speech by a lowest significant digit watermark embedding algorithm, and synthesizing the high frequency part of the wide band speech by the extracted high frequency code stream at a decoding end so as to obtain wide band speech. The invention provides a novel scheme of layered encoding of creating a hidden channel in the narrow band speech transmission for transmitting the encoded code stream of high frequency signals in the layered encoding protocol, thereby not only utilizing the advantages of good vision effect of wide band speech obtained by layered encoding, but also not changing the transmission rate of the current network. As shown in a simulation test, the high frequency noise introduced by the wide band speech obtained by the method is small, and the vision effect has small difference with the original wide band speech.

An LED power-source circuit includes an input filter circuit including noise prevention capacitors and a line filter, a diode bridge connected to the input filter circuit, a smoothing capacitor connected to an output of the diode bridge and having a capacitance of 1 μF or less, a DC-DC conversion circuit connected to the smoothing capacitor, and an LED assembly connected to an output of the DC-DC conversion circuit. Grounding capacitors are coupled to ground from an input power line between the line filter and the diode bridge. The total capacitance from the input power line to ground is set to be 1 / 200 or less of that of the smoothing capacitor.

Eye prescriptions may be determined by providing a simple, easy to use, portable device with a specially configured targeting light source that aligns the eye, mitigates accommodation, and provides accurate results. Unlike stationary, closed view autorefractors, this device typically is portable, self-usable, relatively inexpensive, enabling more widespread use across the world.

The invention provides an optical comb system for implementing wideband carrier enveloped offset frequency control with electro-optic crystal. After femtosecond pulse generated by a femtosecond laser source is coupled into an optical fiber by an optical fiber coupler, the output power is divided into three portions by an optical fiber beam splitter, wherein one portion is transmitted to an fr detection device to obtain an fr signal, the other portion enters an fceo generation and detection device to obtain an fceo signal, and another portion is used as the output of the optical comb system; the fr signal and the fceo signal are respectively mixed with an external reference signal and then output to a corresponding phase-locked loop circuit, fr and fceo feedback control signals are respectively obtained by phase discrimination and proportional integral processing, and then the femtosecond laser source is driven by the fr and fceo feedback control signals to lock fr and fceo to a stable external reference source. The optical comb system can realize wideband locking of an optical comb fceo, so that the control bandwidth of fceo reaches the magnitude of megahertz, and then a high-precision optical comb system is obtained.

Disclosed herein is a linear vibration motor. The motor includes a stator and a vibrator. The stator includes a magnet. The vibrator includes a coil facing the magnet. A weight is coupled to the coil. A PCB is connected to the coil and the stator. An elastic member is coupled to stator and the coil. A damper is provided on the weight at a position facing the elastic member. The damper may be provided between the elastic member and the weight or between the elastic member and the inner surface of a casing. The damper can mitigate metallic high frequency noise attributable to friction between the elastic member and the weight or between the elastic member and the casing. Furthermore, the spatial utilization is increased, thereby enhancing the degree of freedom in designing the linear vibration motor.

In a DC power supply including a transformer, for making a semiconductor switch operate with a high frequency, an auxiliary circuit that reduces switching loss and a countermeasure circuit for a surge voltage generated in a rectifier diode are provided. In a DC power supply in which a DC power source 101 and a transformer T are connected via a power conversion circuit and a secondary winding of the transformer T is connected to a load RL via a rectifier diode bridge and a filter circuit to supply power to the load RL, a resonance reactor Lz is provided on an output side of the transformer T, a resonant switch circuit 103 including a parallel circuit of a diode Dz and a semiconductor switch Qz and a resonant capacitor Cz is connected in parallel to the rectifier diode bridge and a snubber circuit including a snubber capacitor Cs, a snubber diode Ds1 and a diode Ds2 for discharge is connected to a serial resonant circuit including the resonance reactor Lz and the resonant capacitor Cz in the resonant switch circuit 103 to absorb a surge voltage.