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公开(公告)号：EP1057259A1
公开(公告)日：2000-12-06
申请号：EP99973514.5
申请日：1999-11-10
发明人： DING, Heping
IPC分类号： H03H21/00
CPC分类号： H03H21/0012 , H03H21/0043 , H03H2021/0054
摘要： Stable adaptive filter and method are disclosed. The invention solves a problem of instability associated with Fast Affine Projection adaptive filters caused by error accumulation in an inversion process of an auto-correlation matrix. The Stable FAP provides updating of the adaptive filter coefficients by solving at least one system of linear equations, whose coefficients are the auto-correlation matrix coefficients, by using one of the descending iterative methods having an inherent stability of operation due to intrinsic feedback adjustment. The results of the solution are used to update the filter coefficients. The above approach is applicable for any value of a normalized step size ranging from zero to unity. It allows either direct determining of an updating part of the filter coefficients without determining an inverse auto-correlation matrix, or determining the inverse auto-correlation matrix by descending iterative methods.
摘要翻译： 公开了稳定的自适应滤波器和方法。 本发明解决了在自相关矩阵的反演过程中由误差积累引起的快速仿射投影自适应滤波器的不稳定性问题。 稳定FAP通过使用由于内在反馈调整而具有固有的操作稳定性的下降迭代方法中的一种，通过求解至少一个系数为自相关矩阵系数的线性方程组来提供自适应滤波器系数的更新。 解决方案的结果用于更新滤波器系数。 上述方法适用于范围从零到一的归一化步长的任何值。 它允许直接确定滤波器系数的更新部分而不确定逆自相关矩阵，或者通过下降的迭代方法来确定逆自相关矩阵。
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公开(公告)号：EP0795986A3
公开(公告)日：2000-11-22
申请号：EP97301456.6
申请日：1997-03-04
CPC分类号： H04L27/30
摘要： An adaptive Infinite Impulse Response (IIR) filter is provided that can adaptively detect the presence of one or more tones in its input stream. The tones to be detected may be of arbitrary frequency, subject only to a limitation that such tones fall within a frequency band consistent with accepted sampling principles ( e.g. , a maximum frequency of interest no greater than one-half the sampling frequency -- Nyquist sampling criteria). An IIR filter developed according to the method of the invention will adaptively locate the frequencies of tones to be detected, thereby allowing for frequency drift from nominal expected frequency values with no loss in accuracy. Such a filter will also process the input signal sample-by-sample, thereby avoiding the blocking problem of FFT-based filter approaches. With the filter of the invention, an application can identify the frequencies, associated power levels, SNR and duration of the tones. Thus, such an application can use a simple user specified library of tone parameters to decide if tones of interest are present in the input stream.
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公开(公告)号：EP0720799A4
公开(公告)日：2000-04-05
申请号：EP94929808
申请日：1994-09-15
申请人： TELCORDIA TECH INC
IPC分类号： H03H21/00 , H03H17/00 , H04B1/12 , H04B1/7103 , H04B3/06 , H04B7/005 , H04L27/30 , H04B1/10 , H04B1/707 , H04L1/00
CPC分类号： H04B1/7103 , H04B1/123
摘要： Circuitry and concomitant methodology for demodulating Direct-Sequence, Spread-Spectrum Code-Division Multiple-Access (DS/SS CDMA) channel signal using multiple samples per transmitted symbol and a minimum mean squared error criterion to suppress interference. In one embodiment, a bank of cyclically shifted filters (502) determined with reference to the conventional matched filter (401) for CDMA is used to demodulate the channel signal. In another embodiment, a bank of sub-filters (601, 602) determined with reference to the conventional matched filter (401) for CDMA is employed to demodulate the channel signal. In yet another embodiment, the output of a conventional matched filter is oversampled to demodulate the channel signal. Each embodiment utilizes a set of adaptive coefficients selected to minimize the mean square error between the transmitted symbol and detected symbol.
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64.发明公开
公开(公告)号：EP0956650A1
公开(公告)日：1999-11-17
申请号：EP96936374.0
申请日：1996-10-10
CPC分类号： H04L25/0305 , H03H21/0012 , H04B1/126 , H04L1/06 , H04L25/03038 , H04L25/03044 , H04L2025/0363 , H04L2025/03656
摘要： A method and apparatus for separating and removing distortion from interfering co-channel singals and suppressing adjacent-channel interfering signals of the Gaussian Minimum-Shift Keyed (GMSK) or other MSK type with filtering structures that exploit the cyclostationarity of the received GMSK or other MSK signals in order to accommodate a greater number (or the same number, but with greater quality) of transmitted signals received by one or more antennas than can be accommodated by existing filters. The parameters in these filtering structures are adapted by either of two adaptation apparatus that exploit both the known training sequence that is transmitted in most wireless communications systems, and the constant modulus property exhibited by each of the transmitted GMSK or other MSK signals.
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公开(公告)号：EP0951798A1
公开(公告)日：1999-10-27
申请号：EP97915587.0
申请日：1997-04-02
CPC分类号： H04M9/082 , H03H21/0043 , H04R3/02
摘要： In a video conference facility, an echo cancelling device is provided which comprises an adaptive finite impulse response filter (38) operable to sample the input signal to a loudspeaker (30) and to model, on the basis of that signal, the signal fed back to a microphone (32). The echo cancelling device further comprises a combiner (36) for subtracting the model feedback signal from the microphone output signal to provide a corrected microphone output signal, and a microprocessor (40) programmed to read the corrected and uncorrected microphone output signal and to compute updates to the weights of the filter (38), the computation including a multiplication by a variable scaling factor which varies in accordance with the ratio of a first value indicative of the long-term average power of the sound being fed back to a second value indicative of the short-term average power of the sound being fed back. In this way, undesirable fluctuations in the modelled output signal which cause unnatural sounding echoes at the other video conference site are reduced.
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公开(公告)号：EP0659312A4
公开(公告)日：1999-08-04
申请号：EP94921222
申请日：1994-06-01
CPC分类号： H04L25/061 , H04L25/064 , H04L25/066
摘要： A decision feedback equalizer is suitable for use with a bipolar return-to-zero receiver. The equalizer determines an output Y(n) (160) based on a compensated received value X(n) (104) and a correction factor, D(n) (141). After receiving X(n), the equalizer then forms an equalized received value X'(n) (107) based on combining X(n) with D(n). The equalizer then determines the output value Y(n) based on comparing X'(n) with a positive threshold, V1 and a negative threshold, V2. When Y(n) is determined to be zero, the equalizer adjusts the stored correction value D(n) by a predetermined value, DELTA , based on whether X'(n) is positive or negative.
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67.发明授权NEURONALE FILTERARCHITEKTUR ZUR NICHTLINEAREN ADAPTIVEN STÖRINTERFERENZBESEITIGUNG 失效神经滤波器架构非线性自适应STÖRINTERFERENZBESEITIGUNG
公开(公告)号：EP0607393B1
公开(公告)日：1998-12-16
申请号：EP93917527.9
申请日：1993-08-06
发明人： TRESP, Volker, Dr.
IPC分类号： H03H21/00
CPC分类号： H03H21/0016
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公开(公告)号：EP0755141A3
公开(公告)日：1998-10-21
申请号：EP96302841
申请日：1996-04-23
发明人： BORAY GIRIDHAR K
CPC分类号： H04L25/03057
摘要： A digital communication system and corresponding feedback equalization method are described for use in reducing multi-path distortions, such distortions being diminished by employment of an adaptive conjugate gradient algorithm wherein weight coefficients of feed-forward and feedback filter taps are updated recursively during transmission of each data symbol. Weight coefficients are updated based on converging transmission error values, the weight coefficients being updated until either a predetermined number of updates are made, or until the current transmission error value is less than or equal to a predetermined percentage of the initial transmission error value for the given symbol.
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公开(公告)号：EP0870366A1
公开(公告)日：1998-10-14
申请号：EP96943800.0
申请日：1996-12-23
申请人： ERICSSON INC.
CPC分类号： H03H21/0012
摘要： An extended coefficient resolution range is provided in an adaptive filter arrangement by utilizing several filters, in combination, to represent the extended resolution range. The coefficients of a first filter represents a high portion of the extended range, while the coefficients of the second filter represent low portions of the extended range. The two filters operate in parallel to filter an input signal, and the outputs of the filters are combined to produce the filtered signal. A low portion of the coefficients of the first filter overlap an upper portion of the coefficients of the second filter. The coefficients of the first filter are periodically updated from the overlapping portions of the coefficients of the second filter, after which the overlapping portions of the coefficients of the second filter are reset. In accordance with another aspect of the invention, the amount of overlap may be adjusted to dynamically change the resolution range of the filter. The coefficients of the first and second filters are capable of variably overlapping to expand or contract the resolution range in response to changes in the system being monitored. The degree of overlap can also be adjusted to provide an appropriate resolution range corresponding to when the system is stable. An adaptive process is used to up date filter coefficients.
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公开(公告)号：EP0870365A1
公开(公告)日：1998-10-14
申请号：EP96943799.0
申请日：1996-12-23
申请人： ERICSSON INC.
CPC分类号： H03H21/0012 , G10L21/0208 , G10L2021/02082
摘要： A measure of a degree of convergence in an adaptive filter arrangement is derived from the comparison of an amount of adaptation occurring in the adaptive filter arrangement, over a predetermined period of time, with a normalizing value accumulated for the same period. Supplemental signal processing may be invoked, modified or withdrawn based upon the degree of convergence indicated.
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