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公开(公告)号：US5974137A
公开(公告)日：1999-10-26
申请号：US711682
申请日：1996-09-04
申请人： Laurence L. Sheets , Stanley Chmura
发明人： Laurence L. Sheets , Stanley Chmura
摘要： The present invention provides a two-wire line conditioning apparatus having an improved calibration and cancellation circuit and provides an improved calibration method using a multitone calibration signal. The output is monitored by an AGC circuit which controls the output, and prevents hard clipping. This is particularly important for DTMF receivers. Additionally, the apparatus automatically adjusts an electronic hybrid as part of a calibration procedure so as to eliminate undesirable echo effects when calls are placed along the line. The electronic hybrid balancing process and echo cancellation circuitry may also be utilized in a circuit for converting four-wire communications systems to two-wire communications systems. The line conditioning device of the present invention utilizes a multitone signal to simulate the voice frequency spectrum between approximately 500 Hz and 3500 Hz to probe the line side with a plurality of tones (e.g., 500, 1500 and 3500 Hz; or 500, 1000, 1500, 2000, 2500, 3000, 3500 Hz). The amplitude of the tones are weighted to reflect the transmissibility in the voice band. The value of Z.sub.var considered to be optimal is that value which minimizes the power of the echo of the weighted multitone signal. Embodiments are presented that require intervention by a technician for the calibration procedure, and embodiments that automatically perform calibration using dial tone without manual intervention.
摘要翻译： 本发明提供一种具有改进的校准和消除电路的双线调节装置，并提供使用多音校准信号的改进的校准方法。 输出由控制输出的AGC电路监控，并防止硬限幅。 这对于DTMF接收机尤其重要。 此外，该设备自动调整电子混合动力作为校准过程的一部分，以便当沿着线路放置呼叫时消除不期望的回声效应。 电子混合平衡处理和回波消除电路也可以用于将四线通信系统转换成两线通信系统的电路中。 本发明的线路调节装置利用多音信号来模拟大约500Hz到3500Hz之间的语音频谱，以多个音调（例如，500,1500和3500Hz;或500,1000Hz）探测线路侧， 1500,2000,2500,3000,3500Hz）。 音调的幅度被加权以反映语音频带中的传输性。 被认为是最佳的Zvar的值是使加权多音信号的回波功率最小化的值。 呈现需要技术人员进行校准过程的干预的实施例，以及在没有手动干预的情况下使用拨号音自动执行校准的实施例。
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