104results about How to "Reduce echo" patented technology

A method and for optimizing bit rate throughput in a digital communication system is provided. The method includes establishing a relationship between signal to noise ratio and plural symbol rates for a particular constellation size. The method also includes determining noise power spectral density (N(f)), wherein N(f) is determined during a silent period of line probing; determining X_k(f), wherein X_k(f) is determined by turning on a remote station transmit signal, after N(f) has been measured and determining residual echo E_k(f), wherein E_k(f) is determined by turning on a central station echo canceller.

The present invention relates to a method for reducing an echo in a microphone signal generated by a microphone, comprising echo compensating the microphone signal by subtracting an estimated echo signal from the microphone signal to generate an echo compensated signal, detecting a speech activity of a local speaker on the basis of the microphone signal and the estimated echo signal and suppressing a residual echo in the echo compensated signal on the basis of the detected speech activity to obtain an output signal. The invention further relates to a system for processing a microphone signal generated by a microphone, comprising echo compensation filtering means configured to receive and echo compensate the microphone signal to output an echo compensated signal based on the received microphone signal, a speech activity detection means configured to detect speech activity of a local speaker by receiving and analyzing the echo compensated signal and to output a detection signal and a residual echo suppressing means configured to receive the detection signal and to receive and filter the echo compensated signal on the basis of the detection signal to output an output signal.

The present invention relates to a signal processing system, comprising a number of microphones and loudspeakers, a hands-free set configured to receive a telephone signal from a remote party and to transmit a microphone signal supplied by at least one of the microphones to the remote party; an in-vehicle communication system configured to receive a microphone signal supplied by at least one of the microphones; receive the telephone signal; amplify the microphone signal to obtain at least one first output signal; output the at least one first output signal and/or a second output signal corresponding to the telephone signal to at least one of the loudspeakers; and wherein the signal processing systems is configured to detect speech activity in the telephone signal and to control the in-vehicle communication system to reduce amplification of the microphone signal by a damping factor, if it is detected that speech activity is present in the telephone signal.

A packet voice transceiver adapted to reside at a first end of a communication network and to send an ingress communication signal comprising voice packets to, and receive an egress communication signal comprising voice packets from, a second packet voice transceiver residing at a second end of the communication network. The packet voice transceiver includes a far-end echo canceller that reduces echo that is present in the egress communication signal. The far-end communicates with other functional components of the transceiver system and adapts its behavior based on the activity of the other functional components.

An echo canceller (106) can include a first multi-band filter (152) which receives a first input signal (108) and generates a first plurality of sub-band signals (110, 111, 112), and a second multi-band filter (154) which receives a second input signal (122) and generates a second plurality of sub-band signals (156, 157, 158). The echo canceller also can include a plurality of double talk detectors (168, 169, 170) that each generate a double talk flag (182, 183, 184) based on at least a respective one of the first sub-band signals and a respective one of the second sub-band signals.

The present invention provides an echo reduction apparatus, system, and method that advantageously reduces echo when communicating over packet-switched networks. An echo reduction apparatus, including echo reduction circuit, operably couples a headset or handset device to an audio source that is capable of transmitting a sound signal. The echo reduction circuit receives the sound signal from the audio source and a transmit signal from the headset or handset device and provides an adjusted sound signal to the audio source. Advantageously, a variety of headsets and handsets may be used in accordance with the present invention with reduced caller echo and without the need to purchase new headsets or handsets.

A signal generation system suitable for use in a radar system comprises a local oscillator (LO) and an intermediate frequency IF oscillator, wherein the IF oscillator is a Direct Digital Synthesiser, and the LO is a free runn ing oscillator not itself locked to another oscillator but which acts as a c lock reference for the DDS and is the highest frequency oscillator in the sy stem. The LO may also act as a reference for a receive chain digitiser. The invention exploits phase noise advantages of a free running oscillator at so me distance from the carrier whilst maintaining coherency with other system components. The system typically finds application in FMCW radars.

The invention provides a loudspeaker array sound reinforcement system for inhibiting howling. The system comprises an input signal processing module (1), a filter module (2), a multichannel power amplifier (3) and a loudspeaker array (4); the filter module (2) comprises a parameter setting unit (201), a filter group generation unit (202) and a filter group processing unit (203); the filter group generation unit (202) is used for calculating convolution matrixes Hm and Hn formed by time domain impulse response at each control point of the loudspeaker array (4) according to parameters set by the parameter setting unit (201); calculating matrixes Rb and Rd accordingly; calculating a matrix Q according to an average amplitude response fluctuation parameter expression of an equilibrium control point in a sound reinforcement target area; solving a vector w according to Rb, Rd and Q to ensure a maximum value of time domain acoustic energy contrast control of single point equilibrium; converting the vector w into a filter form; and acquiring filter parameters of the filter group processing unit (203).

The invention provides a fly ash glass bead-ferrite compound microwave absorbing material and a preparation method thereof. The compound microwave absorbing material comprises fly ash glass beads andferrite coating the surface of the fly ash glass beads, wherein the ferrite is selected from one or more of barium ferrite BaFe12O19, barium cobalt ferrite BaCox1Fe(12-x1)O19, nickel barium ferrite BaNix2Fe(12-x2)O19 and manganese ferrite MnFe12O19, wherein x1 is 0.5-1, and x2 is 0.5-1. The compound microwave absorbing material has excellent microwave absorbing performance by coating the fly ash glass beads with a specific type of ferrite, has light weight and certain sound absorption effect. The compound microwave absorbing material has a density of 0.6-1g/cm<3>, and has a sound absorption coefficient of 0.34-0.66 and echo reduced by 5-8dB in 1-5kHz.

A method and system to compensate for a drift between a first signal (110) and a second signal (120) is disclosed. The system includes a drift estimator (600) and a resampler (602). The drift estimator (600) receives, as input, for a predetermined amount of time, a first data set containing information related to a sample rate of the first signal (110) and a second data set containing information related to a sample rate of the second signal (120), and produces a one-time estimate of a drift between the first signal (110) and the second signal (120) based on the first data set and the second data set during the predetermined amount of time. The resampler (602) resamples the first signal (110) according to the estimated drift to compensate for the drift between the first signal (110) and the second signal (120).

The invention discloses an axisymmetric double-engine low-scattering carrier for RCS testing and an application method, and belongs to the field of RCS testing of aero-engines. The axisymmetric double-engine low-scattering carrier comprises a carrier body with a smooth curved surface in appearance, wherein the carrier body is divided into a carrier front half section and a carrier rear half section in the axial direction; the carrier is in the shape of a flat cone; two ports are symmetrically formed in the tail end of the rear half section of the carrier by taking the central axis as the center axis and are used for mounting a double-engine spray pipe during an electromagnetic test; and a tail cone is arranged between the two ports, and horizontal tails are symmetrically arranged on the outer sides of the two ports. Horizontal tails on the two sides and a tail cone in the middle are introduced to simulate the layout of an aircraft afterbody, the interior of a nozzle cavity is shielded when radar waves enter from the side direction, and radar echoes are reduced. In addition, the relation between single-engine and double-engine backward RCSs can be researched by testing the scattering characteristics of the double-nozzle backward radar.

The invention discloses a method for improving IP phone echo. At least one audio channel is contained in the method, wherein each audio channel comprises a recording thread, a receiving thread and a playing thread; the recording thread performs audio processing on microphone sound acquired each time through an echo cancellation module and transmits the processed audio data to the opposite side; the echo cancellation module contains a multiband-based echo delay determination method, a least mean square self-adaptive filtering method based on free step length, a single side band nonlinear filterbased on a multiphase structure, a comfort noise generator and a double-talk detection algorithm; and the receiving thread processes audio data sent by the opposite side and then sends the audio datato a buffer zone, and the playing thread processes the audio data in the buffer zone and plays the processed audio data. The method has the benefits as follows: the voice call quality is improved byreducing the echo phenomenon of an IP phone in a call, the internet phone practicability can be improved, the application range of the internet phone is enlarged, and the enterprise cost is reduced.

The invention discloses a method for inhibiting precipitation clutter in radar echo, which comprises the following steps of: firstly, inputting a radar echo image, carrying out mode matching on the radar echo image according to a precipitation noise distributing formula and recognizing the distributing areas of different signals; secondly, marking a suspected target in a dye spot way according tothe distributing characteristics of clutter in different signal areas; then, separating a suspected precipitation clutter signal by a filter and carrying out precipitation clutter recognition on the separated suspected precipitation clutter signal; after carrying out secondary scanning separation on a hidden small target in the precipitation clutter, transmitting a non-precipitation clutter smalltarget to the radar echo image in which the target signal is located; meanwhile, filtering the recognized precipitation clutter; and finally, after properly strengthening the target signal in the processed radar echo image, inputting the target signal into a display system. The invention can carry out effective clutter removal on the radar echo image in severe weather, such as precipitation, and the like.

An echo canceler includes an adaptable filter that is updated during double-talk and far-end talk. The echo canceler receives a microphone signal that includes a near-end signal and echoes resulting from a far-end signal. The echo canceler whitens the far-end signal and decorrelates the microphone signal. The whitening and decorrelating is done as a preprocessing step for the one-unit blind source separation algorithm. A criterion of measure is used to emphasize the statistical independence of the echo canceled signal and the far-end signal. The echo cancellation problem is cast as a one-unit blind source separation problem. A one-unit blind source separation algorithm such as negentropy maximization can be used to extract the echo canceled signal.

The invention discloses a buffering noise reduction ball mill. The buffering noise reduction ball mill comprises a chassis, supporting frames, bearing seats, a cylinder body, a discharge port, a feeding port, a driven gear, a motor seat, a motor, a speed reducer, a driving gear and a sound-proof cover. The supporting frames are vertically welded to the left and right ends of the chassis. The bearing seats are fixed to the tops of the supporting frames. The cylinder body is arranged between the two bearing seats. The discharge port and the feed port are formed in the left and right ends of thecylinder body correspondingly. The driven gear is fixed to the left end of the cylinder body. The motor is mounted at the top of the motor seat. An output shaft of the motor is mounted with the speedreducer. An output shaft of the speed reducer is mounted with the driving gear. The driving gear is engaged with the driven gear. The outer side of the cylinder body is provided with the sound- proofcover. Impact force applied to a lining plate by a steel ball is reduced, the service life of the lining plate is prolonged, the influence of noise in the cylinder body on people is reduced, eardrumsof the people are protected against being damaged, and workers can communicate normally.

The present invention discloses an echo elimination device and method for a miniature hands-free voice communication system. The system comprises a receiver, a primary transmitter and an auxiliary transmitter, a distance from the primary transmitter to the receiver being greater than that from the auxiliary transmitter to the receiver. The device comprises an array echo elimination unit, a self-adaptive echo elimination unit and a residual echo elimination unit, which are structurally cascaded in turn. The array echo elimination unit, with inputs being a signal of the primary transmitter and a signal of the auxiliary transmitter, performs array filtering to obtain one path of output signals; the self-adaptive echo elimination unit, with the input signals being a signal of the receiver, the output signal of the array echo elimination unit and a signal of the auxiliary transmitter, performs self-adaptive filtering to obtain two paths of output signals; the residual echo elimination unit, with the input signals being the two paths of output signals of the self-adaptive echo elimination unit, performs voice probability estimation and echo matching to obtain an echo-eliminated voice signal. Thus, the duplex performance can be enhanced, and the phase consistency of the transmitters is not strictly required.

The present disclosure relates to an audiovisual apparatus, which includes an audiovisual capturing unit, an audiovisual broadcast unit, and a transmission cable module. The two ends of the transmission cable module are respectively connected to the audiovisual capturing unit and the audiovisual broadcast unit. The transmission cable module has a video cable group for transmitting video signals and an audio cable group for transmitting audio signals suitable for reducing echo. The audio cable group includes a cable for providing a digital clock for the audio signal, a cable for providing a clock for the left right channel switching audio signal, a cable for inputting serial audio signal, and a cable for outputting serial audio signal. With this arrangement, the audio signals captured by the audiovisual capturing unit and transmitted by the transmission cable module to the audiovisual broadcast unit can be effectively removed of echo.