| 摘要 |
<p>This interface circuit between a bidirectional line (Lg) and a telephone exchange includes a high frequency transformer (Tr) whose secondary (N2) is connected to said line through a detector circuit (DET) and whose primary (N1) is connected to the switching network of said telephone exchange and to a high frequency carrier source. The circuit further includes means for adjusting the impedances seen across the points where the telephone line is connected to the exchange, so as to meet specified values applicable to the particular location of the exchange. The impedance adaptation means include means (A1) for amplifying the line current variations seen at the center tap (K) of the high frequency transformer (Tr), addition means ( SIGMA 1) for adding the output from (A1) to the voice signal to be sent to the telephone line (Lg), and second amplification means (A2) responsive to the output from ( SIGMA 1) to drive said center tap (K).</p> |
