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公开(公告)号：US4807173A
公开(公告)日：1989-02-21
申请号：US57561
申请日：1987-06-03
CPC分类号： H03H21/00 , H03H21/0027
摘要： A frequency-domain block-adaptive digital filter (FDAF) having a finite impulse response of length N for filtering a time-domain input signal in accordance with the overlap-save method includes window means (11) for obtaining modifications (B(p;m)) of the 2N frequency-domain weighting factors (W(p;m)) from correlation products (A(p;m)). A known FDAF of this type contains five 2N-point FFT's, two of which are used in the window means (11). By utilizing a special time-domain window function which can be implemented very efficiently in the window means (11) with the aid of a frequency-domain convolution, a FDAF of this type containing only three 2N-point FFT's is obtained whose convergence properties are comparable to those of the known FDAF containing five 2N-point FFT's.
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公开(公告)号：US4835765A
公开(公告)日：1989-05-30
申请号：US002080
申请日：1987-01-12
CPC分类号： H04L5/1423 , H04B3/23
摘要： An arrangement for full-duplex data transmission over a two-wire circuit (1) comprises a transmit channel (2) connected to a baseband data transmitter (6) and including a smearing filter (18), a receive channel (3) connected to a baseband data receiver (9) and including a complementary smearing filter (19), a hybrid junction (4), an echo canceller (14) with an adaptive filter (15) and an adjusting circuit (16), and a combining circuit (17) inserted in the receive channel (3). Despite the application of the smearing filters (18, 19) the complexity of the echo canceller (14) is not increased as the arrangement comprises first and second delay means (20, 21) with a delay (D) corresponding to the signal delay of the cascade connection of the smearing filters (18, 19), the first delay means (20) having been inserted in a first signal path from the output of data transmitter (6) to the adjusting circuit (16) and the second delay means (21) having been inserted in a second signal path from the output of data transmitter (6) via the adaptive filter (15) and the combining circuit (17) to a point (P) in the receive channel (3) where the residual signal to be applied to the adjusting circuit (16) is tapped, and the complementary smearing filter (19) in the receive channel (3) has been inserted between the hybrid junction (4) and the tapping point (P) for the residual signal.
摘要翻译： 一种用于通过双线电路（1）进行全双工数据传输的装置包括连接到基带数据发射机（6）并包括拖尾滤波器（18）的发射信道（2），连接到 基带数据接收器（9），包括互补滤波器（19），混合结（4），具有自适应滤波器（15）和调整电路（16）的回波消除器（14）和组合电路 17）插入到接收通道（3）中。 尽管涂抹过滤器（18,19）的应用是回波消除器（14）的复杂度不增加，因为该装置包括第一和第二延迟装置（20,21），延迟装置（D）对应于信号延迟 拖尾滤波器（18,19）的级联连接，第一延迟装置（20）已被插入到从数据发射器（6）的输出到调节电路（16）的第一信号路径和第二延迟装置 21）从数据发送器（6）的输出经由自适应滤波器（15）和组合电路（17）插入到第二信号路径中，到达接收信道（3）中的点（P），其中剩余信号 被施加到调节电路（16）上，并且接收通道（3）中的互补拖尾滤波器（19）已经插入在混合结（4）和漏电点（P）之间用于残留信号。
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公开(公告)号：US4856026A
公开(公告)日：1989-08-08
申请号：US143914
申请日：1988-01-13
摘要： The transmitter (DTR) and the receiver (DRC) of a system for transmitting data signals at a given symbol rate 1/T comprise discrete-time smearing filters (SM and DSM) for combatting the effect of additive pulse-like disturbances (p'(t)) in the transmission channel (TCH). In many cases these disturbances (p'(t)) turn out to have a pronounced bandwidth-limited nature. By utilizing this feature the implementation of the smearing filters (SM and DSM) is simplfied and/or their performance level is improved in that the non-zero values of their impulse responses s(i) and d(j) only occur at the points of grids of the indices i and j recurring with a period of L, where L is an integer greater than 1 and where L is determined substantially by the ratio L.sub.0 of the symbol rate 1/T to twice the highest significant frequency f.sub.m of these disturbances (p'(t)).
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公开(公告)号：US4672633A
公开(公告)日：1987-06-09
申请号：US705779
申请日：1985-02-26
申请人： Theodoor A. C. M. Claasen , Gerardus F. M. Beenker , Petrus J. Van Gerwen , Johannes M. Meijer , Martinus L. N. Didden
发明人： Theodoor A. C. M. Claasen , Gerardus F. M. Beenker , Petrus J. Van Gerwen , Johannes M. Meijer , Martinus L. N. Didden
CPC分类号： H04B1/62
摘要： A data transmission system comprising a transversal smearing filter at the transmitting end and a transversal desmearing filter at the receiving end. To simplify the filters, at least the sequence of coefficients of the desmearing filter is formed by elements of the set {-1, 0, +1}, which results in an optimum smearing of noise pulses in the system compared with a system without such a filter.
摘要翻译： 一种数据传输系统，包括在发送端的横向拖尾滤波器和在接收端的横向去污滤波器。 为了简化滤波器，至少滤波滤波器的系数序列由集合{-1,0，+1}的元素形成，这导致与没有这样的系统的系统中的噪声脉冲的最佳拖尾 一个过滤器
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公开(公告)号：US4903247A
公开(公告)日：1990-02-20
申请号：US210268
申请日：1988-06-23
CPC分类号： H04B3/237 , H04M9/082 , H04B3/234 , H04B3/238 , Y10S367/901
摘要： A digital echo canceller [1] with a good protection against double-talk comprises a first filter [9] for the echo cancellation proper, a second adaptive filter [11] for making continuously adapted filter coefficients available to the first filter [9] and gate means [15] which will only apply the adapted filter coefficients to the first filter [9] if certain conditions are satisfied. In the echo canceller [1] a specific filter combination is used, in which the first filter [9] is a time-domain programmable filter (TDPF) and the second filter [11] is a frequency-domain block-adaptive (FDAF), and further means [20,20(1)] are provided that are arranged in cascade with the gate means [15] for transforming the frequency-domain filter coefficients [W(p;m)] of the FDAF [11] into time-domain filter coefficients [w(i;m)] for the TDPF [9]. These measures result in the advantages of a negligible delay in the echo cancellation by the TDPF [9], and of the possibility to improve in a simple manner the convergence behavior of the FDAF [11] and considerably reduce its computational complexity.
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公开(公告)号：US5278900A
公开(公告)日：1994-01-11
申请号：US680485
申请日：1991-04-04
CPC分类号： H04B3/234
摘要： A digital echo canceller has a receive path (2) and a send path (3) and comprises combining apparatus (10) for forming a send output signal [r(k)] as the difference between the signal [z(k)] applied to the send input (SI) and a replica signal [e(t)] used for cancelling an additive echo signal [e(k)] at the send input (SI) that has developed in response to a receive input signal [x(k)] applied to the receive input (RI), which echo canceller at least includes transforming apparatus (13, 15) for transforming the receive input signal [x(k)] and the send output signal [r(k)]; transforming apparatus (14) for transforming the replica signal [e(k)]; a digital adaptive filter (9) which has a number of filter coefficients for generating the replica signal [e(t)] in response to the receive input signal [x(k)] and the send output signal [r(k)], adaptation apparatus (12) for determining for each block m, adaptation components [A(p;m)] for each of the filter coefficients [W(p;m)] in response to the receive input signal [x(k)] and the send output signal [r(k)]; controllable gate means (17) for selectively passing the adaptation components [A(p;m)] to the adaptive digital filter (9); control apparatus (25-28, 21-24, 16) for determining respective levels of the send output signal [r(k)] and the receive input signal [x(k)] and for generating a control signal for the gate apparatus (17) in response to the levels thus determined, which control signals depend in a predetermined manner on the difference between the levels concerned.
摘要翻译： 数字回声消除器具有接收路径（2）和发送路径（3），并且包括用于形成发送输出信号（r（k））的组合装置（10）作为施加的信号（z（k））之间的差 用于响应于接收输入信号而产生的发送输入（SI），用于消除加性回波信号（e（k））的发送输入（SI）和复制信号（e（t））（x（ k）），该回波消除器至少包括用于变换接收输入信号（x（k））和发送输出信号（r（k））的变换装置（13,15）; 变换装置（14），用于变换复制信号（e（k））; 响应于接收输入信号（x（k））和发送输出信号（r（k）），具有用于产生复制信号（e（t））的滤波器系数的数字自适应滤波器（9） 适应装置（12），用于响应于接收输入信号（x（k））为每个块m确定每个滤波器系数（W（p; m））的适应分量（A（p; m）），以及 发送输出信号（r（k））; 用于选择性地将自适应分量（A（p; m））传递到自适应数字滤波器（9）的可控门装置（17）; 控制装置（25-28,21-24,16），用于确定发送输出信号（r（k））和接收输入信号（x（k））的各个电平，并用于产生门装置的控制信号 17）响应于如此确定的电平，哪个控制信号以预定的方式取决于所涉及的电平之间的差异。
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公开(公告)号：US4768206A
公开(公告)日：1988-08-30
申请号：US40529
申请日：1987-04-20
申请人： Petrus J. Van Gerwen
发明人： Petrus J. Van Gerwen
CPC分类号： H04L25/497
摘要： In DAV (data above voice)-systems an analog speech signal is transmitted in the low-frequency portion of the spectrum of an encoded data signal. When a data signal encoded by the known WAL2 code is used, the high-pass filters, required for the separation of the two signals produce intersymbol interference extending over a large number of bit intervals, requiring complicated equalisers at the receive end for good detection. When encoding the data signal in accordance with the DAV-code, as illustrated in FIG. 2 this drawback is remedied. In addition, this DAV-code is advantageous in that the amplitude fractions, represented by a and b, can basically be chosen at will, allowing the low-frequency content of the code to be affected. When (a; b)=(11/16; 3/16) the encoded data signal can be generated very accurately and in a simple manner.
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公开(公告)号：US4130806A
公开(公告)日：1978-12-19
申请号：US799884
申请日：1977-05-23
CPC分类号： H04L27/06 , H03D3/007 , H03D5/00 , H03D2200/0047 , H03D2200/0056 , H03D2200/006 , H03D2200/0082 , H03D7/165
摘要： A digital filter and demodulation arrangement for passband signals, whose corresponding baseband signal has a bandwidth limited to a given maximum frequency. The passband signals are filtered according to two bandpass characteristics which, apart from their asymmetrical distortion relative to their central frequency, are versions from one another shifted 90.degree. in phase. The filtered passband signals are demodulated with an in-phase carrier and a quadrature carrier and the demodulated signals are combined to a baseband signal.In the digital filtering process the sampling frequency is reduced from a value higher than twice the highest frequency in the passband signals to a value which is not higher than twice said maximum frequency in the baseband signal and in the digital demodulation and combination processes the reduced sampling frequency is also used so that a considerable reduction in the internal processing speed is obtained.
摘要翻译： 用于通带信号的数字滤波器和解调装置，其相应的基带信号的带宽限制在给定的最大频率上。 根据两个带通特性对通带信号进行滤波，除了相对于它们的中心频率的不对称失真之外，它们的相位是相位相差90°。 滤波后的通带信号用同相载波和正交载波进行解调，解调后的信号与基带信号组合。
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9.发明授权Arrangement for correcting pulse distortion in homochronous data transmission 失效用于校正同步数据传输中的脉冲失真的布置
公开(公告)号：US4464746A
公开(公告)日：1984-08-07
申请号：US342984
申请日：1982-01-26
CPC分类号： H04L25/03038 , H04B3/231 , H04L25/03057
摘要： In the duplex transmission of data signals over two-wire transmission paths the phenomenon of echo-signals is encountered, while simultaneously intersymbol interference occurs between the data symbols themselves. In order to reduce the influence of both the echo signals, and the intersymbol interference, the arrangement comprises a random access memory (16) which produces a correction value (c(i)) at each sampling instant to correct the received data signal. The memory is addressed from registers (13, 14) and a counter (15), the contents of the registers being determined by the data ssymbols transmitted last and the data symbols received last, respectively. A D-A converter (19) converts the correction value into a correction signal (c(t)), which in a difference producer (20) is subtracted from the received data signal. A sampling arrangement (21) samples the corrected received data signal. After D-A conversion (22) and multiplication (17) by a predetermined factor .alpha. each sample furnishes a number by which the correction value is changed to match it to the value of the pulse distortion at the sampling instant.
摘要翻译： 在通过双线传输路径的数据信号的双工传输中，遇到回波信号的现象，同时在数据符号本身之间同时发生符号间干扰。 为了减少回波信号和符号间干扰的影响，该装置包括在每个采样时刻产生校正值（c（i））的随机存取存储器，以校正接收到的数据信号。 存储器从寄存器（13,14）和计数器（15）寻址，寄存器的内容分别由最后发送的数据符号和最后接收的数据符号确定。 D-A转换器（19）将校正值转换成从接收到的数据信号中减去差分产生器（20）的校正信号（c（t））。 采样装置（21）对经校正的接收数据信号进行采样。 在D-A转换（22）和乘法（17）乘以预定因子α之后，每个样本提供校正值改变的数量，使其与采样时刻的脉冲失真值相匹配。
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公开(公告)号：US4349889A
公开(公告)日：1982-09-14
申请号：US168211
申请日：1980-07-10
申请人： Hendricus C. van den Elzen , Petrus J. Van Gerwen , Wilfred A. M. Snijders , Nicolaas A. M. Verhoeckx
发明人： Hendricus C. van den Elzen , Petrus J. Van Gerwen , Wilfred A. M. Snijders , Nicolaas A. M. Verhoeckx
CPC分类号： H04L25/03038
摘要： Arrangement having a non-recursive filter and means for weighting a sequence of delayed versions of the input signal in accordance with a sequence of coefficients which are each adjusted iteratively by positive and negative correction steps, respectively, with variable step-sizes, the step-size parameter being selected for each iteration and for each coefficient by means of a run-length detector to which the sign of each correction step is applied and which selects a larger or a smaller step-size parameter depending on the number of correction steps having the same sign and preceding the relevant iteration.Use: echo canceller, equalizer.
摘要翻译： 具有非递归滤波器的装置和用于根据系数序列对输入信号的延迟版本序列进行加权的装置，该系列序列分别通过具有可变步长的正和负校正步骤反复地进行调整， 通过使用每个校正步骤的符号的游程长度检测器对每个迭代选择每个系数的大小参数，并且根据具有该校正步骤的校正步骤的数量来选择更大或更小的步长参数 相同的符号，并在相关迭代之前。 使用：回波消除器，均衡器。
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