| 摘要 |
<p>A bidirectional transmission line is coupled to unidirectional transmission and reception lines by voltage amplifiers to permit transmission of signalling information between telephone exchanges using symmetrical line circuits. A bidirectional transmission line (1) carries information from a transmission line to a reception line. Terminals permit connection of the lines to a coupling network comprising pairs of voltage amplifier. Star networks (RES1, 2, 3, 4) which comprise resistor star circuits are connected to the amplifier outputs. A resistor representing line impedance of the bidirectional line is connected to two of the star networks (RES1, 4) to provide line balancing.</p> |
