47results about How to "Reduce noise power" patented technology

Techniques for direct modulation of a switching-mode power amplifier with adaptive digital predistortion are disclosed. A baseband digital modulated signal is decomposed into an amplitude signal and a phase signal in polar coordinates. The amplitude signal is used to modulate supply voltages of the power amplifier. The phase signal is used to modulate a voltage-controlled oscillator (VCO) of a phase-locked loop (PLL), which generates a phase-modulated radio-frequency (RF) carrier coupled to the input of the power amplifier. The digital predistortion is implemented by using a feedback demodulator, which regenerates the baseband amplitude and phase information from the output of the power amplifier. The VCO drift and other non-linear effects of the power amplifier are compensated. High power efficiency and high linearity for different modulation standards are achieved.

An analog to digital converter comprising an Nth analog to digital converter and an N+1th analog to digital converter arranged in series such that a residue signal from the Nth analog to digital converter is provided as an input to the N+1th analog to digital converter, characterised in that a bandwidth control means is provided in a signal path for the residue signal and the bandwidth control means is controlled so as to have a first bandwidth during a first period following generation of a conversion result from the Nth analog to digital converter, and a second bandwidth less than the first bandwidth in a second period following the first period.

The invention provides a UV detector and a preparation method thereof. The UV detector comprises a substrate. The substrate is successively provided with an n-type layer, an i-type superlattice multiplication layer, an i-type photosensitive absorption layer and a p-type layer. The n-type layer is provided with an n-type Ohmic electrode, the p-type layer is provided with a p-type Ohmic electrode, and the i-type superlattice multiplication layer is a superlattice of group-III nitrides. According to the invention, the problem of difficulty in detecting weak ultraviolet light due to UV detector insensitivity caused by similar ionization coefficients of electrons and cavities by use of a conventional UV detector in the prior art is solved.

In various embodiments, the invention provides a clock generator and/or a timing and frequency reference, with multiple operating modes, such power conservation, clock, reference, and pulsed modes. The various apparatus embodiments include a resonator adapted to provide a first signal having a resonant frequency; an amplifier; a temperature compensator adapted to modify the resonant frequency in response to temperature; and a process variation compensator adapted to modify the resonant frequency in response to fabrication process variation. In addition, the various embodiments may also include a frequency divider adapted to divide the first signal having the resonant frequency into a plurality of second signals having a corresponding plurality of frequencies substantially equal to or lower than the resonant frequency; and a frequency selector adapted to provide an output signal from the plurality of second signals. The output signal may be provided in any of various forms, such as differential or single-ended, and substantially square-wave or sinusoidal.

The invention discloses a two-way multi-order related detection method for a dual-polarization weather radar. The method comprises the following steps: obtaining I/Q (in-phase/quadrature) data of an H (horizontal) channel and a V (vertical) channel; calculating the coherent integration quantities of the H channel and the V channel; calculating the zero-order self-correlation, first-order self-correlation and zero-order cross-correlation quantities of the H channels and the V channels; calculating the weight sum of the multi-order correlation quantity; comparing the weight sum with a threshold value, judging if a weather echo is generated, and if so, calculating the signal-to-noise ratio of the H channel; calculating reflectivity factors under different signal-to-noise ratios; and controlling the quality according to the reflectivity factors, and outputting results. According to the method, the weight sum of the multi-order correlation quantity is introduced in combination with horizontal and vertical polarization echo signals to change a conventional method which simply takes the signal-to-noise ratio of the H channel as a detection factor so as to achieve the purposes of reducing the background noise power and increasing the weak signal detection level, and reduce the loss of the signal-to-noise ratio of an echo wave in a double-transceiver mode.

A wireless communication system for geographically controlling a communication area includes an access point for communicating with a terminal in a first area, and a jammer for generating noise for intercepting communication between the access point and a terminal in a second area. A jamming boundary for dividing an area in which the terminal can communicate with the access point and an area in which the terminal cannot communicate with the access point in an area in which the first area and the second area are overlapped is formed, and the jamming boundary is formed by a ratio between power of a signal transmitted to the terminal by the access point and power of a signal of the noise.

A noise attenuation device for testing a jet engine.

A sampling frequency offset estimation apparatus of an orthogonal frequency division multiplexing (OFDM) system according to an aspect of the invention may include: a first differential operation unit performing complex conjugate multiplication of scattered pilots of complex symbols subjected to a fast Fourier transform (FFT) in an OFDM receiver; an interpolation unit repeating an operation of obtaining a median complex symbol between two consecutive symbols among complex symbols having first phase difference information from the first differential operation unit by a predetermined number; a second differential operation unit performing complex conjugate multiplication of two consecutive median complex symbols among median complex symbols from the interpolation unit; and a sampling frequency offset estimation unit estimating sampling frequency offset using complex symbols having second phase difference information from the second differential operation unit.

The invention relates to the field of wireless signal positioning technology and specifically relates to a virtual multi-station TDOA positioning method and device applicable to a complex environment.The method is characterized in that two to three receivers used for receiving data sent by a positioning transmitting device are arranged; by utilizing a property of the receivers of continuous movement during a positioning process, TDOA data collected by the receivers passing a geographic position is taken as TDOA data collected by a virtual receiver at the geographic position, so that the two to three receivers simulate multiple receivers and multi-station positioning having a station number greater than actual receiver station number is formed for acquiring data information, and proper positioning points are judged by utilizing data relevance; when working, the receivers receive signals transmitted by a transmission device to be positioned through an antenna and send the signals to a processor through a wireless uploading method for process, so that positioning of the transmission device to be positioned is realized. Compared with the prior art, the positioning precision is improved.

Provided is a motor controller for controlling a motor system including a power converter, a smoothing capacitor and a three-phase AC motor. The motor controller includes a generation unit configured to generate a modulation signal by adding a third harmonic signal to a phase voltage command signal, and a control unit configured to control an operation of the power converter using the modulation signal. The third harmonic signal includes a first signal component that causes an absolute value of a signal level of the modulation signal to be greater than an absolute value of a signal level of the phase voltage command signal at a timing in which an absolute value of a signal level of a phase current becomes minimum in each phase

The invention provides a digital decimation filter. The digital decimation filter comprises a cascade integral comb filter, a cascaded Lagrange half-band filter and an FIR filter, which are orderly connected. The digital decimation filter has the advantages of less pass band dropping, small quantized noise power after filtering, and less power consumption.

The invention discloses a coaxial photoelectric component, which includes a tube base and a lens tube cap installed on the tube base, and a transimpedance amplifier and a PIN diode are arranged in the lens tube cap, and the top of the transimpedance amplifier PINA pads, PINK pads and pin pads are arranged on the surface, the bottom surface of the transimpedance amplifier is pasted on the surface of the tube base, the PIN diode is pasted on the top surface of the transimpedance amplifier, and the PIN diode The positive and negative poles of the electrode are respectively connected to the PINA pad and the PINK pad through wires, and the pin pads are connected to the pins on the surface of the socket through wires. Avoid the lead wires connecting the transimpedance amplifier and the PIN diode close to the lead wires connecting the transimpedance amplifier and the tube socket to prevent electrical crosstalk between the leads, reduce noise power, and improve sensitivity.

The invention discloses a direction-of-arrival angle detection method which includes the steps: S1, receiving data signals s (t); S2, converting the data signals s (t) received by a vector array for the t time into a vector form by a vibration velocity sensor and outputting the data signals s (t); S3, projecting output of the vibration velocity sensor in a formula of the step S2 to a certain observation direction to obtain a synthetic vibration velocity expression of the received signals; S4, multiplying a sound pressure matrix with a synthetic vibration velocity matrix to obtain a sound pressure and vibration velocity cross covariance matrix; S5, performing Unitary transformation for the cross covariance matrix to generate a matrix R'=PHRfbP; S6, performing eigenvalue decomposition for the matrix R' after Unitary transformation to obtain an equivalent noise subspace Un'=PUn; S7, generating a polynomial F (z)=zM-1QT (1/z) (Un') (Un') HQ (z) by the equivalent noise subspace, extracting the root of the F (z) and identifying the generated root to obtain a direction-of-arrival angle. By the aid of the technical scheme, detection complexity is reduced, and detection precision is improved.

A method for preparing a vehicle-mounted RFID electronic tag, comprising the following steps: (1) adding a radio frequency amplifier outside the RFID receiver, and using a microstrip line to perform impedance matching on the input end and the output end in order to reduce reflection; An external antenna is added to the outside of the receiver, and the antenna adopts a specific light and small four-arm helical antenna; (3) The baseband digital signal of the receiver is oversampled and filtered, and the data obtained by oversampling can be extracted with a CIC filter to increase the data rate. Return to the normal level, then cascade the FIR filter for band-pass filtering, further reduce the noise power and improve the signal-to-noise ratio; (4) Perform DC offset correction processing on the receiver baseband digital signal, and filter the signal through capacitive AC coupling The DC part is used to reduce the interference of the DC offset; (5) Perform coherent detection data decoding processing on the receiver baseband digital signal.

The flywheel of all internal combustion engine comprises a support and a ring gear. The outer peripheral end of the support has a radial surface and the inner peripheral end of the ring gear has a complementary radial surface. An element of viscoelastic material is situated between the radial surface and the complementary radial surface in such a manner as to put under compression stress in the radial and axial directions.

The invention provides a method for improving the noise of an idle audio channel, which is applied to an audio receiving system of a mobile phone. The method comprises the following steps: generatingan audio signal; and inputting the audio signal to a Sigma-Delta modulator for noise reshaping so as to remove the noise in the audio signal out of a preset tested frequency band. The method can reduce the noise power of the tested frequency band in the audio receiving system of the mobile phone, so the audio receiving system of the mobile phone is endowed with a signal to noise ratio meeting therequirement of a protocol 3GPP TS 26.131. The invention also provides the audio receiving system of the mobile phone.

A data converter comprises a discrete-time sigma delta modulator e.g. for driving a Class-D power amplifier. The low-pass filter of the sigma delta modulator is modified by adding a suitably positioned pole to lower the oscillation frequency (limit cycle) of the sigma delta modulator in order to obtain increased clustering of the pulses applied to the output of the data converter.