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公开(公告)号：US5148427A
公开(公告)日：1992-09-15
申请号：US507595
申请日：1990-04-10
IPC分类号： H04B3/23
摘要： A method and apparatus for echo cancelling linear and nonlinear echo components from a received signal by temporally and spatially separating the overall echo canceller into a fast, transversal filter based linear echo canceller which quickly cancels the linear echoes and a slow, look-up table based nonlinear echo canceller which cancels the nonlinear echo components.
摘要翻译： 一种用于从接收信号中回波消除线性和非线性回波分量的方法和装置，其通过时间和空间将总体回波消除器分离成基于快速的基于横向滤波器的线性回波消除器，其快速消除线性回波和基于慢速查找表 非线性回波消除器消除非线性回波分量。
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公开(公告)号：US5581585A
公开(公告)日：1996-12-03
申请号：US327184
申请日：1994-10-21
CPC分类号： H04L25/03057 , H04L7/0058 , H04L7/0062 , H04L7/0083
摘要： A timing recovery apparatus for recovering the timing from sparse timing information in multi-level or partial response codes. The timing recovery apparatus includes a switch for sampling an incoming line code signal according to a selectable sample rate, a feed forward equalizer for filtering the sampled signal, a decision feedback equalizer for cancelling intersymbol interference in the filtered signal and for recovering the timing in the sampled signal. The timing recovery circuit creates a phase correction signal in response to a signal received from the feed forward equalizer and thereby control the sample rate of the sample switch so that the signal-to-noise ratio at the node before the decision is maximized. The voltage controlled crystal oscillator may be controlled within a certain frequency range by using a second phase detector which compares the phase of the signal controlling the sampling of the incoming line code with a reference clock.
摘要翻译： 一种定时恢复装置，用于从多级或部分响应码中的稀疏定时信息中恢复定时。 定时恢复装置包括用于根据可选采样率对输入线路码信号进行采样的开关，用于滤波采样信号的前馈均衡器，用于消除滤波信号中的码间干扰的判决反馈均衡器，以及用于恢复滤波信号中的定时 采样信号。 定时恢复电路响应于从前馈均衡器接收的信号创建相位校正信号，从而控制采样开关的采样率，使得决定之前的节点处的信噪比最大化。 通过使用第二相位检测器将压控晶体振荡器控制在一定频率范围内，该第二相位检测器将控制输入线路码的采样的信号的相位与参考时钟进行比较。
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公开(公告)号：US5084866A
公开(公告)日：1992-01-28
申请号：US507593
申请日：1990-04-10
申请人： Kenneth G. Buttle
发明人： Kenneth G. Buttle
IPC分类号： H04B3/23
摘要： A transversal filter apparatus having a shift register, an averaging circuit for averaging data stored in sequential shift registers, and a multiplier for multiplying the averaged data. Additionally, a method and apparatus for echo cancelling a transhybrid response having a well behaved portion by using a transversal filter based echo canceller wherein the data stored in adjacent registers of the shift register which correspond to the well behaved portion of the transhybrid response are averaged together prior to being applied to a multiplier. This apparatus and method makes possible a reduction in the amount of hardware required to achieve a given level of echo cancellation.
摘要翻译： 一种具有移位寄存器的横向滤波器装置，用于平均存储在顺序移位寄存器中的数据的平均电路和用于乘以平均数据的乘法器。 另外，一种用于通过使用基于横向滤波器的回波消除器来回波消除具有良好行为部分的逆混合响应的方法和装置，其中存储在移位寄存器的相邻寄存器中的对应于跨杂交响应的良好行为部分的数据被平均化 在被应用于乘数之前。 该装置和方法使得实现给定回声消除水平所需的硬件量减少成为可能。
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公开(公告)号：US5157690A
公开(公告)日：1992-10-20
申请号：US605735
申请日：1990-10-30
申请人： Kenneth G. Buttle
发明人： Kenneth G. Buttle
CPC分类号： H04L25/03057 , H03H21/0012 , H03H2021/007 , H03H2021/0074 , H04L2025/0349 , H04L2025/03585
摘要： An adaptive convergent decision feedback equalizer apparatus and method is disclosed for reducing intersymbol interference (ISI) in a data communication system. ISI is cancelled by generating and subtracting an estimation of the interference from a received signal. the estimation is generated by a N-tap transversal filter in which individual delayed received signals stored in the taps are multiplied by the respective adaptable tap coefficient and summed to form a digital representation of the ISI present. The present invention takes two steps to reduce the probability of coefficient adaptation from diverging. First, the DFE performs a coefficient modification only when the delayed received signal is a particular filter tap is a maximum or minimum level of the selected line code. A second step to eliminate divergence addresses the start up coefficient determination and errors in ISI estimation as the filter coefficients grow in size. On start up, only the first P number of DFE taps are chosen for modification and the remaining taps are held at zero. P is a number of taps for which the sum of the uncancelled ISI and the voltage error of an incorrect ISI estimation yields less than 0.5 probability of an error. After a minimum time (t.sub.min) which insures convergence, the remaining taps (N-P) are enabled.
摘要翻译： 公开了一种用于减少数据通信系统中的符号间干扰（ISI）的自适应收敛判决反馈均衡器装置和方法。 通过从接收到的信号产生和减去干扰的估计来取消ISI。 该估计由N抽头横向滤波器产生，其中存储在抽头中的各个延迟的接收信号乘以相应的适应抽头系数，并相加以形成存在的ISI的数字表示。 本发明需要两个步骤来降低系数自适应的发散概率。 首先，仅当延迟接收信号是特定滤波器抽头是所选行代码的最大或最小电平时，DFE才执行系数修改。 消除散度的第二步是解决ISI估计中的启动系数确定和误差，因为滤波器系数随尺寸的增加而变化。 在启动时，仅选择第一个P数量的DFE抽头进行修改，剩余的抽头保持为零。 P是多个抽头，其中未经校正的ISI和不正确ISI估计的电压误差的总和产生小于0.5的误差概率。 在确保收敛的最小时间（tmin）之后，剩余的抽头（N-P）被使能。
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公开(公告)号：US5461661A
公开(公告)日：1995-10-24
申请号：US281770
申请日：1994-07-28
申请人： Kenneth G. Buttle
发明人： Kenneth G. Buttle
摘要： A circuit for comparing transmitted and received data frames containing appropriate stuff symbols to detect when a channel is disconnected. Transmit data symbols consisting of frames of user data, each with a constant number of symbols, are separated by a sequence of symbols known as the frame pattern. At the end of each data frame, just before the next frame pattern, a small number of stuff symbols are added into the frame. The stuff symbols injected in the transmit signal are chosen to be identical to the last scrambled data symbol in the frame of user data. Stuff symbols in a recovered receive signal are chosen to look identical to data symbols which were scrambled at the remote transceiver. A frame-by-frame comparison between the transmit stuff symbols and the next received stuff symbols is carried out on a continual basis. When the two sets of symbols are equal in each frame for a number of consecutive frames N, then the circuit indicates that only the transmit signal is being received and channel disconnection is detected.
摘要翻译： 用于比较包含适当填充符号的发送和接收数据帧以检测信道何时断开的电路。 由具有恒定数目的符号的用户数据帧组成的发送数据符号被称为帧模式的符号序列分隔开。 在每个数据帧的结尾，恰好在下一个帧模式之前，少量的填充符号被添加到帧中。 在发送信号中注入的填充符号被选择为与用户数据帧中的最后一个加扰的数据符号相同。 选择恢复的接收信号中的信号符号与在远程收发器上加扰的数据符号相同。 在连续的基础上进行发送填充符号和下一个接收的填充符号之间的逐帧比较。 当两组符号在多个连续帧N的每帧中相等时，则该电路指示只有发送信号正在被接收并且检测到信道断开。
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