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    Digitally-tunable echo-cancelling analog front end for wireline communications devices
    1.
    发明授权
    Digitally-tunable echo-cancelling analog front end for wireline communications devices 有权
    用于有线通信设备的数字可调回波消除模拟前端

    公开(公告)号：US06542477B1

    公开(公告)日：2003-04-01

    申请号：US09281903

    申请日：1999-03-31

    申请人： Debajyoti Pal ,  Sujai Chari ,  Christopher Hansen ,  Chung-Li Lu

    发明人： Debajyoti Pal ,  Sujai Chari ,  Christopher Hansen ,  Chung-Li Lu

    IPC分类号： H04B320

    CPC分类号： H04B3/235 ,  H04B3/23

    摘要： The present invention, generally speaking, provides a digitally-tunable, echo-cancelling analog front end (AFE) for wireline digital communications. The analog front end is especially useful in a High-bit-rate Digital Subscriber Line (HDSL) or HDSL2 environment. An analog echo simulation path is provided capable of simulating echo from a wide variety of echo paths. Digitally controlled attenuators are provided in the transmission path and in the analog echo simulation path. Also provided is a digital-tunable equalizer stage. The equalizer stage is tuned to match the characteristics of the receive path. The same arrangement may be adapted for various DSL technologies, i.e., xDSL. There results an analog front end that is well-adapted to high-speed wireline communications.

    摘要翻译： 本发明一般地提供用于有线数字通信的数字可调谐回声消除模拟前端（AFE）。 模拟前端在高比特率数字用户线（HDSL）或HDSL2环境中特别有用。 提供了能够模拟来自各种回波路径的回波的模拟回波模拟路径。 数字控制衰减器设置在传输路径和模拟回波模拟路径中。 还提供了数字可调均衡器级。 调整均衡器级以匹配接收路径的特性。 相同的布置可以适用于各种DSL技术，即xDSL。 结果是模拟前端非常适合高速有线通信。

    Non-linear echo cancellation for wireless modems and the like
    2.
    发明授权
    Non-linear echo cancellation for wireless modems and the like 有权
    有线调制解调器等的非线性回波消除

    公开(公告)号：US06813311B1

    公开(公告)日：2004-11-02

    申请号：US09525452

    申请日：2000-03-14

    申请人： Debajyoti Pal ,  Chung-Li Lu ,  Sujai Chari

    发明人： Debajyoti Pal ,  Chung-Li Lu ,  Sujai Chari

    IPC分类号： H04B138

    CPC分类号： H04B3/23

    摘要： The present invention, generally speaking, provides for cancellation of non-linear distortions within the echo path of a communications system by characterizing the nonlinearity, performing digital processing of a data signal to cause substantially the same nonlinearity to be applied to the data signal, and inputting a resulting data signal to a non-linear echo-cancellation path. In an exemplary embodiment, the non-linear echo-cancellation path includes as a nonlinear echo canceller a transversal filter or the like. A separate linear echo cancellation path is also provided. Training of the nonlinear echo canceller follows training of the linear echo canceller. This technique is particularly applicable to cancelling the effects of DAC nonlinearity, which can be readily characterized. Using this technique, cancellation improvement of about 3dB can readily be obtained. Alternatively, instead of achieving a lower residual echo floor, the linearity requirements for the transmit DAC can be relaxed. A lower number of bits of precision allows for lower DAC power consumption. The technique is particularly applicable to DSL applications.

    摘要翻译： 本发明一般来说通过表征非线性来提供消除通信系统的回波路径内的非线性失真，执行数据信号的数字处理以使得基本上相同的非线性被应用于数据信号，以及 将得到的数据信号输入到非线性回波消除路径。 在示例性实施例中，非线性回波消除路径包括作为非线性回波消除器的横向滤波器等。 还提供了单独的线性回波消除路径。 非线性回波消除器的训练遵循线性回波消除器的训练。 该技术特别适用于消除DAC非线性的影响，可以很容易地表征。 使用这种技术，可以容易地获得约3dB的消除改善。 或者，代替实现较低的残余回波层，可以放宽发射DAC的线性要求。 较低数位的精度允许较低的DAC功耗。 该技术特别适用于DSL应用。