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1014 results about "Signal synthesis" patented technology

The goal of exponential signal synthesis is to define a linear time-invariant (LTI) recursive system that produces an exponential signal in response to an input signal x(n).

Method of bandwidth extension for narrow-band speech

A system and method are disclosed for extending the bandwidth of a narrowband signal such as a speech signal. The method applies a parametric approach to bandwidth extension but does not require training. The parametric representation relates to a discrete acoustic tube model (DATM). The method comprises computing narrowband linear predictive coefficients (LPCs) from a received narrowband speech signal, computing narrowband partial correlation coefficients (parcors) using recursion, computing Mnb area coefficients from the partial correlation coefficient, and extracting Mwb area coefficients using interpolation. Wideband parcors are computed from the Mwb area coefficients and wideband LPCs are computed from the wideband parcors. The method further comprises synthesizing a wideband signal using the wideband LPCs and a wideband excitation signal, highpass filtering the synthesized wideband signal to produce a highband signal, and combining the highband signal with the original narrowband signal to generate a wideband signal. In a preferred variation of the invention, the Mnb area coefficients are converted to log-area coefficients for the purpose of extracting, through shifted-interpolation, Mwb log-area coefficients. The Mwb log-area coefficients are then converted to Mwb area coefficients before generating the wideband parcors.
Owner:NUANCE COMM INC

Method and apparatus for reducing noise in speech and audio signals

A method and apparatus are disclosed for enhancing, within a signal bandwidth, a corrupted audio-frequency signal. The signal which is to be enhanced is analyzed into plural sub-band signals, each occupying a frequency sub-band smaller than the signal bandwidth. A respective signal gain function is applied to each sub-band signal, and the respective sub-band signals are then synthesized into an enhanced signal of the signal bandwidth. The signal gain function is derived, in part, by measuring speech energy and noise energy, and from these determining a relative amount of speech energy, within the corresponding sub-band. In certain embodiments of the invention, the signal gain function is also derived, in part, by determining a relative amount of speech energy within a frequency range greater than, but centered on, the corresponding sub-band. In other embodiments of the invention, the sub-band noise energy is determined from a noise estimate that is updated at periodic intervals, but is not updated if the newest sample of the signal to be enhanced exceeds the current noise estimate by a multiplicative threshold (i.e., a threshold expressible in decibels). In still other embodiments of the invention, the value of the noise estimate is limited by an upper bound that is matched to the dynamic range of the signal to be enhanced.
Owner:INTEL CORP

Method of adaptive full duplex full frequency band echo cancellation

A method of adaptive full duplex full frequency band echo cancellation comprises the following steps of: carrying out filtration by a sub-band filter, carrying out sub-band echo cancellation by a sub-band echo canceller, carrying out weighted energy analysis and control on system signals, carrying out analysis and detection on double talk active state, carrying out coefficient updating on an echo filter, carrying out nonlinear processing on residual echo, and carrying out synthesis on signals of sub-bands. The method further comprises the step of maintaining reference signal and echo signal to be synchronous; after the nonlinear processing is carried out, noise reduction, automatic gain control and comfort noise technique can be added. Owing to adoption of the method of echo cancellation, signals are spilt into sub-bands through filtration, thus reducing correlation among signals of sub-bands, improving convergence problem of adaptive filter, reducing data process load of the system, improving processing efficiency of echo cancellation, realizing full duplex of conversation, improving frequency response of communication audio frequency, improving quality of communication and realizing echo cancellation of full frequency band response.
Owner:南京朗逸锐科电子科技有限公司

New balance detection bias control method for MZ external modulator

InactiveCN101800598AThe adjustment value is accurateRealize closed-loop controlTransmission monitoringElectromagnetic transmissionClosed loopDetection bias
The invention discloses a new balance detection bias control method for an MZ external modulator. The method comprises the following steps: sending RF (radio frequency) signals and pilot signals into a signal end of the MZ external modulator after synthesizing the RF signals and the pilot signals by a signal synthesizer, wherein modulated light signals pass through an optical splitter and part of the optical signals enter an photoelectric detector; converting the part of the optical signals into electric signals by the photoelectric detector; detecting the electric signals; detecting fundamental waves and secondary harmonics of the pilot signals or two or more harmonic components; performing division operation on a transmission function of the two harmonic components and obtaining an adjustment amount of a direct current bias according to a ratio function after the division operation; and obtaining a bias voltage according to the adjustment amount of the direct current bias and sending the bias voltage into the direct current bias end of the MZ external modulator to realize the closed-loop control of an optimal direct current bias point of the MZ external modulator. By using the method, the influence on the precision of a direct current bias control method caused by the output power of a laser and the loss of a link can be eliminated, so that the precision of a system is improved.
Owner:BEIJING INFORMATION SCI & TECH UNIV

Method for improving performance of feedforward narrow-band active noise control system

InactiveCN101976560AImprove performanceReduce residual noise energy impactSpeech analysisSound producing devicesNoise controlSteady state
The invention discloses a method for improving the performance of a feedforward narrow-band active noise control system, which relates to the field of active noise control, and aims at the situation that the reference signal frequency acquired by a non-acoustic sensor in the feedforward narrow-band active noise control system with a minor access road on-line identification function and the target noise actual frequency are imbalanced and the problem the auxiliary noise brought by the minor access road on-line identification seriously hinders the reduction of the residual noise energy of the system. The control system comprises a frequency compensation subsystem, a signal synthesis subsystem and a minor access road on-line identification subsystem; the frequency compensation subsystem comprises a second-order autoregression module and a least mean square (LMS) algorithm module; the frequency compensation subsystem transmits the cosine component and sinusoidal component of the adjusted reference signal of an ith frequency channel to the signal synthesis; when the frequency imbalance reaches above 50%, the target noise can still be effectively restrained; and when in a steady state, the residual noise energy of the system is reduced to an ideal level, so that the performance of the control system can be further improved and is closer to the practice.
Owner:HARBIN INST OF TECH

Satellite communication transceiving assembly and two-dimensional active phased-array antenna

The invention discloses a satellite communication transceiving assembly and a two-dimensional active phased-array antenna. The phased-array antenna comprises a dual-polarized antenna array, a transceiving assembly with a double-radio frequency channel polarization adjusting function, a transceiving feed network, a control and power supply layer, a support framework, a heat dissipation device and a structure accessory. According to the invention, independent polarization adjusting technology of dual-polarization antenna unit in the transceiving assembly is carried out; received N paths of horizontal polarization signals and received N paths of vertical polarization signals are adjusted into N paths of signals through polarization adjustment, and are changed into one path of signal after being subjected to signal synthesis; control of amplitude and phase of polarization adjustment signals is facilitated; and a disadvantage of inappropriate control on the amplitude and phase of signal after the signal is synthesized is overcome. In the phased-array antenna, multiple modules are connected with each other without cables, so space size is effectively used; and a system adopts a phased-array technology to carry out space wave beam scanning, so rapid communication with a satellite system is achieved.
Owner:NO 54 INST OF CHINA ELECTRONICS SCI & TECH GRP

Online aflatoxin detecting device and material sorting equipment adopting same

ActiveCN105044062AEliminate tumblingEliminate the effects of skipping, etc.Fluorescence/phosphorescenceSortingColor imageFluorescence
The invention provides an online aflatoxin detecting device. The online aflatoxin detecting device comprises multiple light source transmitting and signal receiving integration units distributed at the two sides of a material track, and an upper computer. Each illuminating system comprises an ultraviolet source and a rotating reflection mirror which reflects the ultraviolet source to generate a line light source in the material perpendicular direction. Each signal receiving integration unit receives signals of multiple fluorescence wavelengths of bounce light at the same position of the surface of the same material, and converts the signals into electrical signals. The upper computer selects the signals of any three paths to be synthesized into a color image. A sensor in each optical signal receiving device is a single-point photoelectric detector. The invention further discloses material sorting equipment adopting the detecting device. The detecting device has the advantages that the weak fluorescence signals on the surfaces of the materials are effectively detected, each detected material point is only detected by the corresponding single-point photoelectric detector once, signal superposition is avoided, influence of material rolling, jumping and the like is eliminated, and the materials contaminated by aflatoxin and the normal materials are effectively distinguished.
Owner:HEFEI MEIYA OPTOELECTRONICS TECH
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