LINE CIRCUIT FOR COMPENSATION OF INSERTION ATTENUATION DISTORTION

PURPOSE:To keep the service quality at a high level, by compensating distortion of attenuation for the signal supplied from a channel through an input amplifier and at the same time transmitting the signal to a 4-wire channel. CONSTITUTION:The output of an output amplifier Ta is connected to a series part of impedances ZA and ZAL as well as to a series part of impedances ZA and ZAL'. If ZAL is equal to ZAL', the delivered signal gives the same level to both ZAL and ZAL' and is completely canceled during operation through an input amplifier and the signal never to return to a 4-wire channel. While the signal arrived from a circuit emerges at the impedance ZAL and not at ZAL' accordingly the signal from the channel passes an input amplifier Ra and is sent to the 4-wire channel while compensating the distortion of attenuation. For a line circuit B1 which is connected to a line circuit A1 via the 4-wire channel, the distortion of insertion attenuation is compensated by the combination of the circuits A1 and B1 since the circuit B1 has a circuit constitution in that A is exchanged to B.