294 results about "Broadband noise" patented technology

A method of determining whether arcing is present in an electrical circuit includes sensing a change in current in the circuit and developing a corresponding input signal, analyzing the input signal to determine the presence of broadband noise in a predetermined range of frequencies, and producing a corresponding output signal, and processing the input signal and the output signal in a predetermined fashion to determine whether an arcing fault is present in the circuit. The processing includes determining a type of load connected to the electrical circuit, based at least in part upon the input signal and the output signal.

In an adaptive filter for cancelling common-mode noise in digital subscriber loops, a narrowband noise estimator is used to detect one or more noisy frequency bands of the common mode signal and derive therefrom a first noise estimation signal. A wideband noise estimator derives from the remainder of the common mode signal a second noise estimation signal. The first and second noise estimation signals are subtracted from the differential signal, The wideband noise estimator comprises a bandstop filter for removing the frequencies detected by the narrowband noise estimator, an analog-to-digital converter for digitizing the bandstopped signal, and an adaptive filter for deriving the second noise estimation signal from the digitized bandstopped signal and, in the process, compensating for phase and gain differences, especially attributable to the interference being injected at different points along the length of the channel.

A fan system, such as a turbofan, marine propeller, or a cooling fan, includes a fan noise control system for reducing noise generated by the fan system. The noise control system may be configured to reduce either broadband noise, blade-passage noise, or both. In particular, the fan noise control system suitably includes a pre-swirl generator configured to provide a layer of fluid upstream from the fan blades. The layer swirls in the direction of the fan's rotation, reducing the angular velocity differential between the fan blades and the incident fluid. In addition, the fan noise control system may also include a fluid seal generator configured to create a fluid barrier between the fan blade tips and the interior surface of the fluid flow channel. The fluid seal inhibits leakage flow between the fan blade tips and the interior surface as well as the formation of blade vortices. By minimizing the blade wake and the blade tip vortices without adding solid surfaces, noise tends to diminish.

A method and system for determining whether arcing is present in an electrical circuit includes sensing a change in an alternating current in the circuit and developing a corresponding input signal, analyzing the input signal to determine the presence of broadband noise in a predetermined range of frequencies, and producing a corresponding output signal, and processing the input signal and the output signal in a predetermined fashion to determine whether an arcing fault is present in the circuit. The processing includes determining a type of load connected to the electrical circuit, based at least in part upon the input signal and the output signal, and monitoring high frequency noise in a 20 KHz band for each 1/8 cycle of the alternating current.

A method and system for determining whether arcing is present in an electrical circuit. The methods includes sensing a change in an alternating current in the circuit and developing a corresponding input signal, analyzing the input signal to determine the presence of broadband noise in a predetermined range of frequencies, and producing a corresponding output signal. The method further includes determining a type of load connected to the electrical circuit, based at least in part upon the input signal and the output signal, incrementing one or more of a plurality of counters in a predetermined fashion in accordance with the input signal and the output signal and determining whether an arcing fault is present based at least in part on the states of one or more of a plurality of counters. The method also includes decrementing one or more of the plurality of counters based upon a secondary analysis.

The invention discloses an active noise control method for eliminating and reducing noise. An active noise control device is subjected to the operation in the following steps of: (1) identifying a transfer function between a secondary source and an error sensor by using a common LMS (Least Mean Square) algorithm to obtain a transfer function estimating value of a signal transmitting channel; (2) obtaining an output signal y1(n) of an FXLMS (Filtered-x Least Mean Square) algorithm self-adapting filter W(n) according to a primary noise source signal x(n); (3) obtaining an output signal y2(n) of a DFT-FSF (Discrete Forurier Transform-Fast Forurier Transform) algorithm self-adapting filter according to a filtering reference signal of the signal transmitting channel; (4) adding y1(n) and y2(n) to obtain y(n) and respectively obtaining an expected signal d(n) and an error signal e(n) at the error sensor position and an estimating value of d(n); and (5) updating the DFT-FSF algorithm self-adapting filter V(n) and adjusting the FXLMS self-adapting filter W(n); and repeating the steps (2) to (5) and gradually reducing e(n) to achieve the aim of noise reduction at the error sensor position. The invention has the advantage of combining and utilizing the favorable benefits that an FXLMS algorithm is suitable for narrowband noise reduction and a DFT-FSF algorithm is suitable for broadband noise reduction and greatly reduces computation burden.

An apparatus for analyzing the broadband noise content of a digital image comprising the following: a means of automatically identifying regions of originally constant color in the image by analysis of the variance of pixel values of regions of the image; a means of automatically detecting and discarding regions deemed to be unrepresentative of the true noise content of an image, including under- and over- exposed regions; a means of allowing the user to manually select some or all required constant color regions if desired; and, a means of analyzing such constant color regions to generate a parametric or non-parametric model of the noise in the image, including frequency characteristic within and between channels and other characteristics such as phase which might describe structured noise.

An arc fault circuit interrupter includes separable contacts, an operating mechanism and an arc fault detector structured to detect an arc fault condition operatively associated with the contacts. The arc fault detector includes a tuned current sensor structured to sense broadband noise of a current flowing through the contacts, a compression circuit including an input of the sensed broadband noise and an output. The compression circuit compresses the dynamic range of the sensed broadband noise. A minimum detector includes an input of the compression circuit output and an output of the minimum value of the minimum detector input. A processor includes a number of inputs and an output. One of the inputs is the output of the minimum value of the minimum detector. A trip mechanism cooperates with the output of the processor and the operating mechanism to trip open the contacts responsive to the detected arc fault condition.

A system for determining whether arcing is present in an electrical circuit in response to a sensor signal corresponding to current in the circuit includes a circuit for analyzing the sensor signal to determine the presence of broadband noise in a predetermined range of frequencies, and producing a corresponding output signal. A controller processes the sensor signal and the output signal to determine current peaks and rise times and to determine, using the current peaks and rise times and the presence of broadband noise, whether an arcing fault is present in the circuit, by comparing data corresponding to the current peaks and rise times and broadband noise with preselected data indicative of an arcing fault. The circuit for analyzing and the controller are integrated onto a single application specific integrated circuit chip.

The invention belongs to the technical field of ultrasonic cavitation detection and signal analysis, and relates to a method and a device for separating and detecting focused ultrasonic cavitation signals. An ultrasonic transducer of a device emits cavitation detecting signals in a pulse-inversion mode, and another ultrasonic transducer receives acoustic signals diffused by ultrasonic cavitation and movement of microbubbles; a transducer of another device generates cavitation signals in the pulse-inversion mode; for each cavitation detecting experiment, the detection method extracts background signals when the cavitation does not happen, respectively calculates power spectrums of the acquired cavitation acoustic signals and the background signals, calculates the subtracted power spectrum estimation and phase position estimation, and converts the power spectrum estimation and the phase position estimation into time domain signals to filter noise of a system; and an ICA method separates target signals such as broadband noise component, subharmonic and the like in cavitation acoustic signals from other signal components and extracts characteristic parameters of the cavitation acoustic signals. The detection method has high sensitivity and can perform quantitative analysis.

The invention relates to a carrier-borne full-coherent phased-array radar calibrator which comprises a local oscillator module, upper and lower frequency mixing modules, an intermediate frequency processing module, a target distance, a speed simulation module, a broadband noise generating module, a master control platform and the like, wherein the local oscillator module is divided into first and second local oscillator modules; the upper frequency mixing module is divided into first and second upper frequency mixing modules; the lower frequency mixing module is divided into first and second lower frequency mixing modules; the master control platform comprises a CPCI (Compact Peripheral Component Interconnect) motherboard, a power supply, a keyboard, a display, an external interface and a clock and delay control circuit; and each module and each component of the master control platform are supplied with power and carry out data exchange by the CPCI motherboard. According to the invention, a radar echo signal synthesized by overlaying a target and a broadband noise power can be vividly simulated and the detection capacity of the target under the noise interference of a carrier-borne full-coherent phased-array radar can be tested. The carrier-borne full-coherent phased-array radar calibrator has good application prospect in the technical field of calibration and checking of the phased-array radar.

A device 20 includes a receiver 21 for receiving and processing signals at least in a first frequency band and an antenna 216 which is connected to the receiver 21. In order to improve the performance of such a receiver, the device 20 in addition includes a tuning component 217 for shifting a frequency response of the antenna 216 from the first frequency band to a second frequency band. Further, the device 20 includes a controlling portion 221 causing the tuning component 217 to shift the frequency response of the antenna 216 from the first frequency band to the second frequency band, in case a wideband noise is expected in the first frequency band. A corresponding method is shown as well.

The invention provides a real-time frequency domain super-resolution direction estimation method and a device, and the method comprises the following steps: 1) dividing a linear array for obtaining M1sub-arrays; 2) respectively carrying out beamforming on a time-space two-dimensional signal of each sub-array for obtaining an output beam of each sub-array on the scanning direction; 3) carrying outsynthesis treatment on the output beams of various sub-arrays on the scanning direction for obtaining a multi-sub-array synthetic beam; and 4) and obtaining the target direction according to the multi-sub-array synthetic beam obtained by the step 3). The invention provides the real-time frequency domain super-resolution direction estimation device. The method and the device have the following technical effects: (1) the calculation is highly efficient, the speed is fast, the DSP engineering is convenient to realize, and the real-time treatment can be realized; (2) the method and the device areapplicable to broadband noise target direction finding; (3) the high-resolution beam can be obtained; and (4) compared with the frequency domain beamforming algorithm in the prior art, the method andthe device can obtain beam output with even narrow main lobe and even weak strength of a side lobe, thereby obtaining the target direction estimation with higher resolution.

Embodiments of the disclosure are directed to optical dark section conditioning. An embodiment generates at least one of a broadband noise or signal at the head end of a section for a first module of the section; and operates all other modules of the section in gain control mode.

The invention discloses a high-linearity broadband stacking low noise amplifier based on a gain compensation technology. The high-linearity broadband stacking low noise amplifier comprises a two-stacking low noise amplification network, an interstage matching network and a two-stacking gain expansion amplification network which are connected in sequence; and a first power supply bias network and a second power supply bias network which are connected with the two-stacking low noise amplification network and the two-stacking gain expansion amplification network. According to the high-linearity broadband stacking low noise amplifier, a serial stacking structure is realized through adoption of two transistors with different sizes and ultra wide band noise and impedance matching are realized through combination of an RLC feedback network; through utilization of the gain compression compensation technology, the gain compression property of the two-stacking low noise amplification network is cancelled within a certain bias range through the two-stacking gain expansion amplification network and a linearity index of the amplifier is improved, so the whole low noise amplifier has good broadband, linearity, low power consumption and low noise amplification capability; and moreover, the low breakdown voltage property of an integrated circuit technology is avoided and the stability and reliability of a circuit are improved.

The invention discloses a centrifugal pump flow induction noise numerical prediction method which is used for computing the sound source feature of flow noise on the basis of the test results of a centrifugal pump performance test. The method can well overcome the shortcomings that in a traditional computing method, the influence from a pump body structure on acoustic propagation is not considered, and eddy broadband noise is ignored. Centrifugal pump inner flow analysis and far-field noise value computing results are used in centrifugal pump low-noise waterpower design, test frequency can be reduced, the development cycle can be shortened, development cost can be saved, the design quality of a centrifugal pump can be effectively improved, an interpolation method is used between a fluid mesh and an acoustics mesh, sound source information of flow field calculation can be reserved to the maximum degree, GREEN analysis is used, the contribution degree on noise from different parts of a shell body can be obtained, such study is carried out, and early design or later modifying of the shell body can be optimized.