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178results about How to "Reduce nonlinear distortion" patented technology

Digital signal processor for audio extensions and correction of nonlinear distortions in loudspeakers

Digital filters for processing an input audio signal for extending the audio capabilities and reducing distortion of a loudspeaker. Such extension may include a general sound pressure level (SPL) extension or a more targeted low frequency (LF) extension. This may be accomplished by modifying an original frequency response of the loudspeaker to achieve a particular extension, and applying a digital linear filter based on the modified frequency response to the audio signal. A nonlinear digital filter may also be applied to the audio signal reduce nonlinear distortions of the loudspeaker. The nonlinear digital filter may be based on an inverse of an electro-mechanical model of the loudspeaker. In this manner, a loudspeaker may be driven close to its maximum theoretical power capability without increasing distortion in the loudspeaker output.
Owner:THE UNIV OF UTAH

Loudspeaker, video device, and portable information processing apparatus

A loudspeaker according to the present invention includes: a diaphragm that vibrates back and forth to emit a sound; a magnetic circuit that is provided on a rear side of the diaphragm and has a magnetic gap on a diaphragm side; a voice coil that is directly or indirectly joined to the diaphragm and disposed within the magnetic gap; a magnetic fluid that is loaded within the magnetic gap; and a plurality of first edge pieces that are provided at different positions in an outer circumferential portion of the diaphragm for vibratably supporting the diaphragm, each of the first edge pieces having a non-linear cross-sectional shape.
Owner:PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

Reduction in acoustic coupling in communication systems and appliances using multiple microphones

A system and method of digitally modeling and significantly reducing the direct coupling between a telephone appliance loudspeaker and microphone employs a handset microphone in a phone appliance, such as, for example, a speakerphone, as a reference channel along with the speakerphone microphone to reduce the direct coupling between the speakerphone loudspeaker and the speakerphone microphone. Using an analog adaptive echo cancellation scheme, the sensitivity and dynamic range of a telephone device microphone to speech from talkers in an enclosure but not from signals emitted by a telephone loudspeaker are enhanced. Nonlinear distortions produced by a telephone appliance loudspeaker are measured by a telephone appliance handset microphone and used in a feedback subsystem, e.g., network, to reduce nonlinear distortions in the telephone appliance loudspeaker and loudspeaker driving circuit.
Owner:AVAYA TECH CORP

Amplifier linearizer

The present invention provides an advanced adaptive predistortion linearization technique to dramatically reduce nonlinear distortion in power amplifiers over a very wide instantaneous bandwidth (up to 2 GHz) and over a wide range of amplifier types, input frequencies, signal types, amplitudes, temperature, and other environmental and signal conditions. In an embodiment of the invention, the predistortion linearization circuitry comprises (1) a higher-order polynomial model of an amplifier's gain and phase characteristics—higher than a third-order polynomial model; (2) an adaptive calibration technique; and (3) a heuristic calibration technique. The higher-order polynomial model is generated by introducing, for example, a plurality of multi-tone test signals with varying center frequency and spacing into the power amplifier. From the power amplifier's corresponding output, the nonlinearities are modeled by employing a higher-order curve fit to capture the irregularities in the nonlinear transfer function. Different distortion transfer functions can be implemented for different operating conditions. The adaptive calibration technique is based on a feedback analysis technique, which updates the applicable distortion transfer function by analyzing the error signal between the introduced input signal and the output signal in real-time. The heuristic calibration technique implements different distortion transfer functions based on historical operating conditions and optimal configurations of the power amplifier.
Owner:TM IP HLDG LLC

Wireless optical orthogonal multi-carrier communication method with low peak to average power ratio

The invention discloses a wireless optical orthogonal multi-carrier communication method with a low peak to average power ratio. The wireless optical orthogonal multi-carrier communication method comprises the following steps that at a transmitting end, firstly, modulated frequency domain signals are converted into a semi-positive definite planning convex optimization problem by adopting a tone injection algorithm via a relaxation method, and solving is carried out through general convex optimization and randomized methods; secondly, the frequency domain signals are symmetrically mapped to subcarriers in a conjugate mode, and a cyclic prefix is added after reverse fast Fourier transformation; at last, time domain transmission signals are added into direct-current offset to drive a light-emitting diode to emit light. At a receiving end, photovoltaic conversion is achieved through a photodiode; signals are removed from the cyclic prefix and conjugate symmetry parts after amplification, filtering, analog-digital conversion and fast Fourier transformation; the signals are modulated to be recovered in an original planisphere; at last, receiving symbols are obtained through demodulation. According to the wireless optical orthogonal multi-carrier communication method, the peak to average power ratio of a wireless optical communication PFDM system can be effectively reduced, requirements of a power amplifier and an LED for linear degrees are reduced, non-linear distortion is reduced, and receiving performance is improved.
Owner:SOUTHEAST UNIV

Amplifier linearizer

The present invention provides an advanced adaptive predistortion linearization technique to dramatically reduce nonlinear distortion in power amplifiers over a very wide instantaneous bandwidth (up to 2 GHz) and over a wide range of amplifier types, input frequencies, signal types, amplitudes, temperature, and other environmental and signal conditions. In an embodiment of the invention, the predistortion linearization circuitry comprises (1) a higher-order polynomial model of an amplifier's gain and phase characteristics—higher than a third-order polynomial model; (2) an adaptive calibration technique; and (3) a heuristic calibration technique. The higher-order polynomial model is generated by introducing, for example, a plurality of multi-tone test signals with varying center frequency and spacing into the power amplifier. From the power amplifier's corresponding output, the nonlinearities are modeled by employing a higher-order curve fit to capture the irregularities in the nonlinear transfer function. Different distortion transfer functions can be implemented for different operating conditions. The adaptive calibration technique is based on a feedback analysis technique, which updates the applicable distortion transfer function by analyzing the error signal between the introduced input signal and the output signal in real-time. The heuristic calibration technique implements different distortion transfer functions based on historical operating conditions and optimal configurations of the power amplifier.
Owner:TM IP HLDG LLC

Amplifier Linearizer

The present invention provides an advanced adaptive predistortion linearization technique to dramatically reduce nonlinear distortion in power amplifiers over a very wide instantaneous bandwidth (up to 2 GHz) and over a wide range of amplifier types, input frequencies, signal types, amplitudes, temperature, and other environmental and signal conditions. In an embodiment of the invention, the predistortion linearization circuitry comprises (1) a higher-order polynomial model of an amplifier's gain and phase characteristics—higher than a third-order polynomial model; (2) an adaptive calibration technique; and (3) a heuristic calibration technique. The higher-order polynomial model is generated by introducing, for example, a plurality of multi-tone test signals with varying center frequency and spacing into the power amplifier. From the power amplifier's corresponding output, the nonlinearities are modeled by employing a higher-order curve fit to capture the irregularities in the nonlinear transfer function. Different distortion transfer functions can be implemented for different operating conditions. The adaptive calibration technique is based on a feedback analysis technique, which updates the applicable distortion transfer function by analyzing the error signal between the introduced input signal and the output signal in real-time. The heuristic calibration technique implements different distortion transfer functions based on historical operating conditions and optimal configurations of the power amplifier.
Owner:TM IP HLDG LLC

Dynamic compensation method for reducing LED (Light Emitting Diode) nonlinear distortion of visible light Flip-OFDM (Orthogonal Frequency Division Multiplexing) communication system

The invention relates to a dynamic compensation method for reducing LED (Light Emitting Diode) nonlinear distortion of a visible light Flip-OFDM (Orthogonal Frequency Division Multiplexing) communication system. The method comprises the following steps: segmenting a modulated subcarrier data vector into a plurality of non-overlapped subsequences; multiplying by a corresponding weighting coefficient, extending to be a hermitian symmetric sequence and then performing IFFT (Inverse Fast Fourier Transform); selecting a weighting coefficient for keeping the negative signal amplitude of a combined signal to be minimum; decomposing the polarity of the combined signal into a Flip-OFDM positive signal and a flip negative signal and limiting the amplitude; carrying an end cut signal of the positive signal at a zero signal position corresponding to the flip negative signal as a compensation signal; restoring the positive signal by a receiving end through the compensation signal. By using the method, PAPR (Peak to Average Power Ratio) in the Flip-OFDM system can be effectively suppressed, and the LED nonlinear distortion is reduced, so that the usability and the reliability of the system are greatly improved.
Owner:THE PLA INFORMATION ENG UNIV

Compensated peak-to-average ratio non-linear distortion new algorithm based on compression perception technology

InactiveCN106506430ASuppresses and compensates for nonlinear distortionReduce complexityMulti-frequency code systemsNonlinear distortionCommunications system
A compensated peak-to-average ratio non-linear distortion new algorithm based on a compression perception technology belongs to the communication technology field. The algorithm comprises the following steps of (1) based on a CS theory, using an empty carrier wave to carry out peak-to-average ratio amplitude limiting compensation; and (2) carrying out OMP error tolerance value estimation based on an LS algorithm. The algorithm has advantages that (1) a receiver can accurately recover an amplitude of a signal before amplitude limiting; (2) generation of an amplitude limiting noise is greatly reduced, and simultaneously non-linear distortion of a linear amplifier is reduced so that system performance is effectively increased; and (3) algorithm complexity is low and an obvious improvement effect is possessed for an aspect of amplitude limiting noise reduction. The improved amplitude limiting algorithm based on compression perception is better than a common amplitude limiting algorithm, certain practicality is possessed and a certain reference value is possessed for a high-speed real-time OFDM underwater sound communication system.
Owner:HEILONGJIANG UNIVERSITY OF SCIENCE AND TECHNOLOGY

Wine bucket shaped loudspeaker box

The invention discloses a wine bucket shaped loudspeaker box, comprising a loudspeaker box body and a loudspeaker box bracket; the loudspeaker box body comprises a wine bucket shaped box body and a loudspeaker arranged at the front end surface of the box body, a phase-reversing tube is arranged in the box body, a phase-reversing hole is arranged at the rear end surface of the box body, one end of the phase-reversing tube is arranged at the position of the phase-reversing hole and is vertically and fixedly connected with the rear end surface of the box body, the loudspeaker is electrically connected with an external sound source by a loudspeaker wiring terminal, wave mode sound absorption wool is arranged on the inner wall of the box body, the wine bucket shaped loudspeaker box eliminates the harmonic distortion and resonance of tone quality, caused by flat box body surfaces and edge corners of a common resonance, increases low-frequency diving power and reduces nonlinear distortion of audio frequency, the design of the wine bucket shaped box body changes the disadvantage that the common loudspeaker box has poor shock resistance, promotes the mechanical property of the loudspeaker box structure and can support high audio-frequency power; in addition, the wine bucket shaped appearance design of the loudspeaker box is artistic and elegant, and the function and the decoration are perfectly combined.
Owner:王强

Radar and Communication (RadCom) system based on OFDM and carrier joint optimization

The invention belongs to the technical field of communication, and relates to an OFDM-based Radar and Communication (RadCom) system. The method is based on the traditional OFDM system, and is characterized in that at a transmitting end, bit streams to be sent are modulated into data symbols, local waveform retention designing is carried out according to a data bandwidth ratio through the data symbols and a random phase sequence to obtain RadCom frequency domain signals, the signals are then mapped into the time domain through IFFT, Cyclic Prefix (CP) addition is carried out on the mapped signals, and signals obtained through the CP addition are sent to a channel through a radio frequency front end; at a receiving end, CP removal is carried out on the received signals, signals obtained through the CP removal are mapped into the frequency domain through FFT, the mapped signals are equalized to compensate for channel distortions, symbol extraction is carried out on the equalized symbols according to the data bandwidth ratio, and bit information is finally obtained through symbol demodulation; and meanwhile, the frequency domain signals at the transmitting end and the receiving end areused for radar processing. The system provided by the invention has the advantages that the partly retention loop algorithm is introduced, so that the bandwidth can be flexibly allocated under the premise that the advantages of a communication system are maintained, the PAPR can be effectively reduced, and the spectrum utilization efficiency can be improved.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA

Micro-transducer with improved perceived sound quality

The typical micro-transducer dedicated for mobile phones and headphones produces at high output in small back enclosure significant distortion in the acoustical output. These typical micro-transducers are designed for very high sensitivity and their mechanical suspension compliances are designed for worst case scenario, free air environment or a very large back enclosure (were the air stiffness from the back enclosure is much lower than the mechanical transducer suspension stiffness). This leads to poor low frequency response, high distortion, non-linear SPL characteristic and unnecessary high system resonance fre-quency when the transducer is placed in a small back enclosure. The Soft Suspension Long throw (SSL) micro-transducer has been designed with an improved non-circular shaped magnetic system, a low density / high Young's modulus thermal conducting diaphragm, a large-area non-circularly shaped diaphragm area, a non-circular shaped voice coil and a soft long-throw suspension which has been designed so that the SSL micro-transducer only functions properly when mounted in a small back enclosure. The combination of these inventions leads to a transducer architecture offering significant improvements in overall distortion, high RMS power handling, extended bass reproduction, also in compact volumes, and an overall flat frequency response. The combined result of several inventions is a significant overall improvement in perceived sound quality.
Owner:BANG & OLUFSEN ICEPOWER

X-waveband power amplifier based on GaN

The invention discloses an X-waveband power amplifier based on GaN. The X-waveband power amplifier comprises MIN capacitors, a filter capacitor, a thin-film resistor, a stable resistor, a spiral inductor, a microstrip transmission line, a T-shaped connector and a GaN-based HEMT. A signal input end (RFIN) is connected with an input end (1) of the GaN-based HEMT (H) through the first MIN capacitor (C1), the microstrip transmission line (W) and the T-shaped connector (T). A drain electrode control end (Vds) is connected with an output end (2) of the GaN-based HEMT through the microstrip transmission line (W) and the T-shaped connector (T). The microstrip transmission line (W) is a 100-micrometer high-impedance microstrip transmission line. A 100-microfarad electrolytic capacitor is selected as the filter capacitor. The GaN-based HEMT (H) is an NRF01-02a HEMT tube core. The thin-film resistor is made of NiCr material. The X-waveband power amplifier is matched with the input end in a conjugate mode through a load traction method so as to solve the problem that negative resistance occurs at the port of the transistor; the X-waveband power amplifier is stable in work, has the bandwidth of 3.6 GHz to 8.0 GHz, the maximum gain of 11.04 dB, the maximum output power of 33 dBm and the maximum PAE of 29.2%, and is small in voltage standing wave ratio.
Owner:WUXI YANAO ELECTRONICS TECH
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