374 results about "Matched filter" patented technology

The invention discloses an electromagnetic interference suppression method based on time-domain periodic phase modulation. The electromagnetic interference suppression method comprises the following steps: constructing a mathematical model of a radar echo signal which is modulated by a phase modulation surface of a target, namely is interfered; constructing a reference signal, and performing dechirp processing on the interfered radar echo signal by using the reference signal; performing frequency and duty ratio estimation on a frequency spectrum of a modulation signal, namely an interference signal, through a signal obtained after dechirping processing, and reconstructing the modulation signal at a receiving end according to an estimation result; carrying out time delay on the reconstructed modulation signal, and multiplying the reconstructed modulation signal with an interfered ground radar echo signal to obtain a demodulated signal; carrying out carrier removal processing on the demodulated signal, and then carrying out pulse pressure processing through a matched filter; and changing the time delay value of the reconstructed modulation signal, namely carrying out sliding window operation on the reconstructed modulation signal in the time domain, and determining the modulation starting time by utilizing the relationship between the maximum value of pulse pressure processing and the time delay, thereby recovering a real radar echo signal.

The invention relates to an optical cable monitoring and data analysis method and device, equipment and a medium. The method comprises the following steps: acquiring current state data of an optical fiber link, and dynamically generating adaptive pulse coding parameters and matched filter parameters based on the data by using a deep reinforcement learning agent, so as to generate and inject coded pulses into the optical fiber link; and then receiving an echo signal, performing matched filtering processing on the signal by using the generated matched filter parameter to obtain a filtering output signal, further calculating a performance index vector and a reward signal, and finally updating a strategy network of the intelligent agent by using the reward signal, thereby realizing continuous optimization of pulse coding and matched filtering parameters. Therefore, the system can automatically adapt to the dynamic change of an optical fiber link, the spatial resolution, the dynamic range and the signal-to-noise ratio are effectively improved, and the adaptive capability and the robustness of the system are enhanced at the same time.

The invention discloses an inter-Doppler interference suppression method based on a Gaussian learning factor particle swarm algorithm. The inter-Doppler interference suppression method comprises the following steps that pilot frequency and data symbols are coded to a resource grid of a two-dimensional time delay Doppler domain through orthogonal time-frequency space modulation; on a transmitter, mapping data on a time delay Doppler domain grid to a time-frequency domain through inverse symplectic finite Fourier transform to obtain a time-frequency domain signal; performing Hisenberg transformation on the time-frequency domain signal to obtain a time domain sending signal; obtaining a time domain receiving signal after the time domain sending signal passes through a wireless channel; performing Doppler compensation processing on the time domain receiving signal by using Doppler frequency shift to obtain a signal after Doppler compensation; then performing matched filtering on the signal after Doppler compensation and a received pulse, and sampling to obtain a matched filter output signal; and the matched filter output signal is subjected to the Sextile Fourier transform to obtain a time delay Doppler receiving signal. The method can realize suppression of inter-Doppler interference to a certain extent.

The invention relates to the technical field of radar communication, and discloses a detection identification method and system based on frequency modulation and pseudo-random coding, and the method comprises the steps: a detection device sets waveform parameters, and generates and transmits a Chirp signal to a target device through a radar transmitter; the target device performs frequency and phase modulation on the incident Chirp signal through the electromagnetic metasurface, and then reflects the modulated Chirp signal; and the detection equipment adopts a Chirp signal obtained in the same modulation mode as the target equipment as a matched filter, performs matched filtering on the received echo signal, calculates the code and the distance of the target equipment, and realizes radar detection and target identification. According to the invention, the target passively performs frequency and phase modulation on the incident radar signal through the electromagnetic metasurface, and the detection method can solve the target modulation coding information by knowing the target echo modulation mode so as to identify the target.

The invention discloses a foundation pit support deformation real-time monitoring method based on edge calculation, and aims to solve the problems of multi-node time synchronization and clock drift compensation caused by unavailability or poor quality of satellite navigation and precise time protocols in an underground or shielded environment. According to the method, through event dictionary learning, partition time slot scheduling and safety coding micro excitation time synchronization, matched filtering decoding, multi-scale arrival time estimation, paired time difference robust fusion, frequency priority and phase speed limit correction and network disconnection time holding, the time synchronization efficiency is improved; the technical effects that multi-source data alignment, deformation field reconstruction and graded early warning are completed on the unified virtual reference time scale, and high-precision synchronization and online drift compensation are obtained without depending on the external time service condition are achieved.

The invention provides a distributed optical fiber sensing vehicle signal enhancement method, device and equipment, and the method comprises the steps: carrying out the framing processing of a to-be-processed vehicle signal, and obtaining a time-frequency feature corresponding to the to-be-processed signal; the time-frequency characteristics comprise frequency distribution characteristics and time-domain characteristics; constructing a template signal based on the time-frequency characteristics, and designing a corresponding matched filter by using the template signal to obtain a target filter; the template signal at least comprises a principal component of the time-frequency characteristic; and matching the target filter with the to-be-processed vehicle signal filtered by the band-pass filter to obtain a target vehicle signal. By analyzing the time-frequency characteristics of the to-be-processed vehicle signal, the template signal capable of being matched with the vehicle vibration signal is found, and the template signal is matched with the to-be-processed vehicle signal after band-pass filtering, so that the influence of interference noise on the original vehicle signal is removed, and the enhancement of the vehicle signal under the condition of strong interference noise is realized.

The invention discloses a sparse polarization MIMO radar multi-parameter estimation method based on tensor decomposition, and the method comprises the steps: firstly constructing a dual-station MIMO radar system based on a polarized antenna, and calculating a covariance matrix of a receiving signal of a matched filter of a receiving end; then converting the covariance matrix into a tensor form, performing dimension transformation on the tensor, and obtaining a virtual covariance tensor of continuous virtual array elements in the difference joint array by using two transformation matrixes; dividing the virtual covariance tensor into a plurality of sub-tensors and connecting the sub-tensors along a fifth dimension and a sixth dimension; and finally, tensor decomposition is performed on the tensor obtained after connection, and multi-dimensional parameter estimation of the far-field target can be realized by using a matrix obtained through decomposition. The method has the advantages that joint estimation of the direction of arrival, the direction of departure and the polarization parameters is achieved under the underdetermined condition, and the estimation precision is high.

The invention discloses an LFM frequency hopping signal long-distance target echo detection method, terminal equipment and a storage medium, and the method comprises the steps: constructing the two-dimensional time-frequency features and one-dimensional matched filtering features of a target echo, extracting the two-dimensional time-frequency features through employing a CNN network, and extracting one-dimensional time sequence features through an SE-CNN-GRU network; carrying out weighted fusion on the multi-dimensional features through a self-adaptive weighted fusion module; a multi-head attention mechanism is introduced to enhance the fused features; and outputting a classification result through the full connection layer and the Softmax layer to obtain a detection result of the target echo. According to the method, one-dimensional matched filtering and a two-dimensional time-frequency graph are selected as input features of the artificial intelligence detection method, the advantages of different artificial intelligence networks are fully utilized to perform multi-dimensional feature mining, adaptive weighted fusion is performed through complementarity and correlation of the multi-dimensional features, and the fused features are further enhanced through an attention mechanism, so that the detection accuracy of the artificial intelligence detection method is improved. Therefore, the target echo detection capability is improved, and high detection accuracy and robustness can be realized in a low signal-to-noise ratio environment.

The invention discloses a device for realizing wireless high-precision time synchronization based on an FPGA (Field Programmable Gate Array), and also discloses a method for realizing wireless high-precision time synchronization based on the FPGA. According to the invention, a time sequence can be strictly controlled by adopting a method for recording a timestamp by adopting hardware at an FPGA end, and the sending time delay is eliminated; besides, the position for recording the sending timestamp is close to the radio frequency end, so that accumulated time delay caused by sending processing time delay can be reduced, and delay uncertainty caused by clock domain crossing of processing data can be reduced. And finally, a sequence detection method is adopted after the filter module is matched, and the arrival time of the timestamp of the receiving end is judged at the first time, so that the uncertainty time delay caused by an algorithm existing in receiving processing can be reduced.

The invention relates to the field of radar detection and signal processing, and particularly discloses a radar data technology system for monitoring a tiny target, and the system comprises a signal receiving and transmitting module which is used for generating and transmitting a linear frequency modulation signal based on a linear frequency modulation technology, and receiving an original echo signal reflected by the target; the pulse compression processing module is used for performing complex convolution operation on the original echo signal based on a matched filter to generate a compressed pulse signal; the multi-pulse coherent accumulation module is used for performing frequency domain energy accumulation on a plurality of compressed pulse signals of the same distance unit based on a discrete Fourier transform technology; and the Kalman filtering tracking module is used for processing the signals after multi-pulse coherent accumulation through a Kalman filtering algorithm, predicting and updating a target state in real time, and generating final trace point data. According to the invention, through key technologies of large-time wide-bandwidth pulse compression, multi-pulse coherent accumulation and the like, the detection capability of the radar on a tiny target is remarkably improved.

The invention provides a digital receiver circuit and a control method thereof. The digital receiver circuit comprises a frame synchronization detection module, a symbol synchronization detection module and a symbol decoding module, the frame synchronization detection module comprises a first matched filter and a first peak detection module; the first matched filter is used for performing convolution operation on a guide code sequence in the received synchronization signal to obtain a convolution operation result; the first peak value detection module is used for determining the position of a convolution peak value according to the convolution operation result; determining the end position of the guide code sequence according to the position of the convolution peak value; the symbol synchronization detection module is used for detecting positioning information of an end position of each symbol in effective data connected with the guide code sequence; according to the positioning information, determining a pulse sequence corresponding to a judgment moment of symbol decoding of the effective data; and the symbol decoding module is used for performing symbol decoding on the effective data according to the judgment time and the pulse sequence. The technology can improve the accuracy of signal detection and decoding.

The invention discloses a mangrove forest extraction method based on orthogonal matched filtering-weighted least square, and relates to the technical field of remote sensing and image processing. According to the method, through preprocessing and band expansion, the whitened orthogonal subspace projection and the whitened matched filter method are combined, and mangrove forest feature information is effectively enhanced; then, a weighted least square filtering technology is introduced, and the edge information of the mangrove forest image is further enhanced; and finally, carrying out adaptive threshold segmentation on the remote sensing image by using an Otsu method so as to realize target extraction of the mangrove forest region. The method has the advantages of low cost, high precision, short time and the like. The problems that in the prior art, the labor cost is high, the efficiency is low, a neural network method lacks enough representativeness and coverage, the mangrove forest cannot be effectively recognized and extracted under various complex backgrounds, and the adaptability and the accuracy are not high are solved.

The invention provides a low earth orbit satellite signal capturing method based on PMF-FFT. The low earth orbit satellite signal capturing method comprises the steps that firstly, low earth orbit satellite downlink signals are received and frequency mixing is carried out; carrying out adjustable parameter window adding processing on the frequency-mixed signal; inputting the windowed signal into a PMF module, and carrying out correlation calculation on the windowed signal and a local pseudo code to obtain PMF module output; carrying out adjustable parameter window adding processing on the output of each segmented matched filter in the PMF module; performing N-point FFT on the output result of the segmented matched filter; performing normalization processing on the FFT result of the # imgabs0 # point to obtain a normalized amplitude-frequency response; and performing threshold judgment according to the normalized amplitude-frequency response to realize capture. The method not only solves the problems of difficulty in broadband capture, long capture time and poor anti-Doppler effect of the traditional signal capture method, but also solves the problem that the traditional PMF-FFT method cannot break through a preset capture threshold and misses capture due to the fact that the normalized power spectral density at the target Doppler frequency shift is reduced due to energy loss under the condition of low signal-to-noise ratio. Therefore, the low-orbit satellite navigation signal can be quickly captured.

The invention discloses a multi-time slot MAMP receiver and coding method for an MIMO multicarrier modulation system, comprising a time domain linear estimation module gamma l (.) and a symbol domain nonlinear estimation module phi l (.), where l represents the number of iterations; the time domain linear estimation module adopts a matched filter to recover the received time domain signal to obtain an estimated value of the time domain signal; transforming the estimated value into a symbol domain through unitary transformation; and the symbol domain nonlinear estimation module calculates a log-likelihood ratio of each symbol and calculates an estimated value of each symbol through estimation of the symbol domain returned by the time domain linear estimation module. According to the method, the optimal MSE detection performance can be realized with extremely low complexity in a multi-time-slot transmission scene.

The invention relates to a GMSK signal incoherent demodulation method and device. The method comprises the following steps: obtaining a state grid chart by utilizing multi-symbol detection; obtaining a matched filter according to the state grid chart; enabling the received baseband signal to pass through a matched filter to obtain a signal correlation value; obtaining a branch metric value of each state node in the baseband signal according to the signal correlation value; updating the path metric value of each state node according to the branch metric value; reserving a path corresponding to the maximum path metric value of each state node, and taking the path as a surviving path of each state node; and backtracking the survival path of each state node to obtain demodulation data of the baseband signal. According to the method provided by the invention, the state grid is obtained through multi-symbol detection, and multiple pieces of symbol information are combined, so that the problem of insufficient memory length in related technologies is solved, errors are prevented from spreading along the grid, and the error probability of symbol judgment during demodulation is reduced.

The invention discloses a target long-time accumulation method based on ADMF (Amplitude Dimethyl Formamide) under an FDA (Frequency Division Amplification) radar area array system, which mainly solves the problem of insufficient target detection capability caused by weak received target echo energy and low signal-to-noise ratio of received signals when the existing FDA system radar realizes wide-coverage wide-area target monitoring. According to the implementation scheme, the method comprises the following steps: establishing an area array echo model combined with an azimuth-dimension FDA and a pitch-dimension phased array; constructing a time-angle two-dimensional matched filter under a plane array system in which the azimuth FDA and the pitching phased array are combined, and performing matched filtering on echo signals; performing first-order KT conversion and Doppler fuzzy compensation on the echo signal after matched filtering to realize range walk correction; and carrying out distance dimension IFFT and slow time dimension FFT on the corrected signal to obtain a signal after phase-coherent accumulation. Through long-time coherent accumulation of the target, the echo energy of the FDA radar target can be improved, the signal-to-noise ratio can be reduced, the target detection probability can be improved, and the method can be used for detecting a weak high-speed moving target.

The invention discloses a cable defect identification and positioning method and device based on time-varying matched filtering. Relates to the power equipment state detection technology and the application field thereof. The method comprises the following steps: connecting a measured cable to measuring equipment through a connecting line; disconnecting the measured cable and the connecting line, injecting a pulse signal by the measuring equipment, and measuring a reflected signal vos (t) generated when the tail end of the connecting line is short-circuited; the measured cable and the connecting line are connected, the measurement equipment keeps setting parameters unchanged, and a reflection signal in the measured cable is obtained; designing a time-varying matched filter based on a reflection signal generated when the tail end of the connecting line is short-circuited, filtering the reflection signal in the tested cable to obtain a filtered reflection signal curve, and determining reflection time through an extreme point on the filtered reflection signal curve; and calculating the position lf of the cable defect according to the reflection time. According to the invention, the detection capability of the time domain reflection technology on small defects in the cable and in a noise environment is improved, and the method has a wide application prospect.

The invention belongs to the field of metasurface electromagnetic signal processing, and particularly relates to a deep learning aided design-based metasurface two-dimensional high-resolution signal source positioning method. The super-surface two-dimensional high-resolution signal source positioning method based on deep learning aided design comprises a matched filtering algorithm and an image denoising algorithm. The method comprises the following steps: firstly, performing principle analysis and mathematical modeling on a metasurface two-dimensional signal source positioning function based on a ray tracing method and metasurface physical parameters to obtain a matrix equation; secondly, performing matrix inverse operation on the equality by adopting a matched filtering algorithm, preliminarily estimating two-dimensional position information of the signal source, and outputting the two-dimensional position information in an image form; and finally, inputting image information into the image denoising deep neural network by adopting an image denoising algorithm, and finally realizing two-dimensional high-resolution signal source positioning. According to the high-resolution signal source positioning method, multiple times of simulation and experiments are carried out on the basis of the two-dimensional gradient programmable metasurface platform, and a large number of data results prove that the method has the advantages of high resolution, low complexity and the like.

The invention provides a distributed optical fiber sound wave sensing system and device based on a frequency shift ring. The distributed optical fiber sound wave sensing system comprises a narrow linewidth laser source module, a sweep frequency optical pulse generation module, a radio frequency signal generation module, a circulator, a coherent receiving and photoelectric conversion module and a signal acquisition and processing module. The sweep frequency optical pulse generation module comprises an acousto-optic modulator, a frequency shift ring, an optical fiber coupler and an optical amplifier, the acousto-optic modulator generates narrow-bandwidth sweep frequency optical signals, the frequency shift ring is composed of an acousto-optic frequency shifter, a time delay optical fiber and the optical amplifier, the acousto-optic frequency shifter achieves frequency shift, the time delay optical fiber achieves time delay of the optical signals, and the optical amplifier compensates loss of the optical signals. And the spliced optical pulse enters a sensing optical fiber, returned Rayleigh backscattered light and local light are subjected to beat frequency, a matched filter generated by deconvolution is used for processing a beat product signal, and a vibration signal is demodulated. According to the invention, the frequency-shift ring is spliced to obtain a wide-bandwidth sweep-frequency optical signal, and high-spatial-resolution vibration detection is realized.

The invention provides a carbon monoxide plume identification and quantification method based on a domestic hyperspectral satellite, and the method comprises the steps: carrying out the radiometric calibration and atmospheric correction of the data of a visible short-wave infrared hyperspectral camera AHS I carried by the domestic hyperspectral observation satellite (GF-5B, Gaofen-5 B satellite); generating a carbon monoxide unit absorption spectrum by using a medium-resolution atmospheric transmission model MODTRAN; inverting a carbon monoxide enhancement value by adopting a matched filtering method; generating a binary plume mask through threshold segmentation; and constructing a deep learning model based on a residual neural network ResNet network, and realizing plume pixel-level identification and carbon monoxide column concentration enhancement value prediction. The method can identify the carbon monoxide plume with high precision and high efficiency, and is suitable for atmospheric pollution monitoring and pollution source quantification.

The invention discloses an intermittent sampling and forwarding interference suppression method, which belongs to the technical field of radar anti-interference signal processing, and comprises the following steps of: after receiving an echo signal with interference, minimizing an interference suppression ratio and a generalized integral sidelobe ratio of a non-matched filter as a target, and taking signal-to-noise ratio loss as a constraint condition; constructing a non-matched filter optimization model; and constructing an augmented Lagrange function to solve the non-matched filter optimization model, and outputting an optimal non-matched filter. According to the non-matched filter optimization model, the signal-to-noise ratio loss is used as a direct constraint condition, the output result of the non-matched filter is more directly displayed, compared with other methods, multiple constraint terms are fused into the model, the constraint conditions are reduced, the optimal result is easier to achieve through a single constraint condition, and the optimization effect is better.

The invention relates to a long-time accumulation detection method based on a bistatic radar, and the method comprises the steps: firstly constructing a bistatic radar detection model, and receiving an echo signal generated by the reflection of an external radiation source signal through a target; pulse compression, distance dimension FFT, multiplication with a frequency response function generating a distance matched filter, conjugate multiplication with an exponential term causing distance migration, distance-Doppler dimension fast Fourier transform processing, Keystone linear frequency modulation Z transform processing and distance dimension IFFT processing are sequentially carried out on the echo signal, and a fifth echo signal is obtained; and carrying out peak detection on the fifth echo signal to detect the target and obtain the motion parameters of the target. Compared with the prior art, the method has the advantages of reducing energy accumulation loss caused by quantization errors when FFT processing is not interpolated in the distance dimension, effectively completing distance migration correction and pulse accumulation, reducing operation complexity caused by long-time accumulation and the like.

The invention relates to the technical field of noise filtering, in particular to an electronic circuit with a transmission line type noise filter, and the electronic circuit comprises a frequency determination device which is used for determining the working frequency and voltage of the electronic circuit; the device determining device is used for selecting a microstrip line as a transmission line and optimizing the filter by using a composite right / left hand transmission line and an open-circuit T-shaped structure; the impedance matching device is used for matching the impedance of the filter with the impedance of the transmission line; the matching measuring device is used for measuring the impedance matching effect by using a reflection coefficient and a VSWR (Voltage Standing Wave Ratio); and the software simulation device is used for simulating and optimizing the matched filter and transmission line by using simulation software. According to the invention, the impedance of the filter is matched with the impedance of the transmission line, so that the impedance change of the signal in the transmission process is reduced, the reflection of the signal is reduced, and the transmission quality and efficiency of the signal are improved.

The invention discloses a maneuvering target long-time coherent accumulation method, system and device and a medium, and relates to the technical field of radar signal processing, and the method comprises the steps: enabling a plane array to achieve the complete airspace coverage in the azimuth angle range dimension through the introduction of FDA; according to the planar array, three-dimensional information of a target is utilized, so that the target can obtain information with higher dimensionality than that of coherent FDA. Then, an azimuth angle-pitch angle-distance three-dimensional matching filter is designed, and rapid waveform matching is realized. The method aims at the influence of a maneuvering target phase-coherent accumulation process. And finally, compensating range migration and Doppler frequency migration in a high-altitude maneuvering target detection process by adopting a second-order Keysone transform-LVD algorithm to realize coherent accumulation of the target. The invention not only provides a novel radar array combining PA and FDA, but also is applied to the field of target detection, especially for complex detection conditions such as high-altitude maneuvering targets.

The invention provides a frame header synchronization method based on a CPM constant envelope spread spectrum sequence, and belongs to the technical field of satellite-borne satellite communication. A traditional recursive feedback type structure based on a phase-locked loop (PLL) is optimized, and a matched filter, a resampling module and a delay locked tracking loop (DLL) module are added after frame header pulse detection and frequency offset estimation are completed by utilizing the differential self-correlation characteristic of a synchronous sequence. The single symbol rate timing error estimation result serves as negative feedback and is fed back to the matched filter for resampling operation, the optimal resampling point is continuously adjusted, the symbol synchronization establishment time is greatly shortened, and then frame header synchronization of LINK20 received signals is achieved. The method has the advantages of being easy to implement, low in complexity and high in real-time performance and synchronization precision.

A method and an apparatus for determining information regarding the location of energy deposition of an ion beam, in particular a proton beam, in an absorptive medium, such as in the tissue of a patient undergoing radiation therapy.

Systems and methods for anatomical identification using ultrasonic imaging and acoustic shadow detection methods are provided. At least some embodiments of the disclosure comprise the following steps: acquiring ultrasound image; detecting shadow region; extracting shadow profile; filtering shadow profile with matched filter; identifying anatomical landmarks within shadow; extracting features of anatomical landmarks; classifying anatomy, and determining with a high degree of confidence that the target anatomy is depicted in the image. A determination is made as to the degree of confidence that the target anatomy is depicted in the image. Conditionally, graphics indicating presence and position of target anatomy is displayed including disposition, location and orientation thereof.

The invention discloses a strabismus mode ground interference source positioning method and system based on a satellite platform, a storage medium and electronic equipment, and the method comprises the following steps: firstly, carrying out the range pulse compression of a received interference signal according to the related parameters estimated by the prior information of an orbit and the time-frequency relation; constructing a matched filter, realizing linear range migration correction, and eliminating a first-order component of range migration in a range frequency domain-azimuth time domain; a CTF search algorithm is used, and under different search distances, distance direction search is achieved through a cooperation mechanism of global search and step length constraint local optimization; constructing matched filters at different distances to realize quadratic term range migration correction, and eliminating a range migration quadratic term in a two-dimensional frequency domain; azimuth distance compression is carried out at different distances, so that signals are focused; and obtaining a two-dimensional positioning position opposite to the interference source through coordinate transformation. According to the invention, the problem of signal defocusing caused by the distance-orientation strong coupling effect is solved in the squint mode, and the interference source positioning precision is significantly improved.

The present invention discloses a signal form and detection method for Barker code modulation of an incoherent laser radar. The steps are: 1: modulating the incoherent laser radar pulses into "0" and "1" signals according to the Barker code rule; 2: transmitting the laser radar signal, reflecting it from a target, and then receiving and processing it by the radar to obtain a corresponding digital signal; 3: applying a certain amount of bias to the digital signal within a pulse repetition period, where the bias value is the average value of the digital signal obtained by receiving and processing the current background light; 4: matching filtering the biased digital signal using the Barker code modulated pulse signal; and 5: further processing the matched filtered signal to detect the target and estimate its parameters. In a low-cost incoherent laser radar system, the application of Barker code modulation to the transmitted signal can achieve a significant improvement in the signal-to-noise ratio through digital pulse compression technology, thereby improving the detection performance and ranging accuracy of the incoherent laser radar.

The audio device comprises a receiver (201) arranged to receive a set of input audio signals. An audio beamformer (101) performs beamforming by combining the outputs of the filters. The feedback circuit (103) comprises a set of matched filters having a complex conjugate frequency response, and the beamforming adapter (105) adapts the filters in response to a comparison of the input audio signal and the feedback audio signal. An adaptation coefficient processor (207) determines decorrelation coefficients for a set of spatial decorrelation filters that generate a decorrelated output signal from an input audio signal, where the decorrelation coefficients are adapted based on the input signal. A set of spatial filters (205, 301, 401) is arranged to apply spatial filtering to the input audio signal or the feedback signal, wherein the set of spatial filters has coefficients determined from the decorrelation coefficients.