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混合线圈是会议电话终端机、汇接设备和载波机等通信设备中的重要部件,作用是将二线电路转换为四线电路。 在会议电话电路中。混合线圈四线端一端接收信支路,一端接发信支路,二线端一端接实线线路,一端按平衡网络。 线路阻抗与平衡网络阻抗不匹配所造成的失配衰耗叫业务平衡衰耗,它表示在工作状态时的衰耗。 目前农村电话线路绝大部份是架空铁线线路,线路阻抗变化范围较大,混合线圈的平衡度却难以做到理想平衡,其业务平衡衰耗一般只能做到30分贝左右,致使发信输出漏到收信输入的信号较强。若收信支路的增益又大,就会形成回音增大或电路振鸣。因此,二线电路开放会议电话稳定性较差,尤其是在对讲时振鸣问题不易解决。
Hybrid Coils are important components in communications equipment such as conference phone terminals, tandem devices, and carrier computers. They are used to convert two-wire circuits to four-wire circuits. In the conference call circuit. One end of the four-wire end of the hybrid coil receives the signal branch, one end connects to the signal transmission branch, the second end is connected to the solid line, and the other end is balanced network. The mismatch loss caused by the mismatch between the line impedance and the balanced network impedance is called service balance loss, which indicates the attenuation in the working state. At present, the vast majority of rural telephone lines are overhead wire lines, and the line impedance has a wide range of variations. However, the balance of the hybrid coils is hard to achieve an ideal balance. The business balance loss generally can only be about 30 dB, Output leakage to the receiver input signal stronger. If the receiving branch of the gain is large, it will increase the echo or circuit vibration. Therefore, the stability of second-line circuit telephone conference call is poor, especially in the intercom vibration problem is not easy to solve.