| 摘要 |
<p>PURPOSE:To attain matching considerably well for many lines by approximating a balancing network of a subscriber's circuit, which is connected to a line having a line length different by subscriber terminal, to the characteristic of the line impedance. CONSTITUTION:When a subscriber's terminal TEL is connected to the far end of the line and the impedance of the line viewed from a subscriber's circuit LN is approximated as a synthesizing circuit of a resistance RL and a capacitor CL, the value of the resistance RL is increased from the resistance value of the subscriber's terminal in accordance with the line length and approximates gradually to a certain value, and the value of the capacitor CL is increased from a minute value to approximate gradually to a certain value, and a duty D of a switching pulse is increased in accordance with a sum RDC of a DC line resistance proportional to the line length and a certain resistance of the subscriber's terminal or the like and is saturated for 100%. The switching pulse is used to control the balancing network, and the circuit constant of the balancing network BN1 is approximated to the line impedance thereby, thus preventing detouring in a two wire-four wire converting circuit.</p> |
