PURPOSE: To prevent the malfunction of a modem from occurring by adjusting an input signal at the optimum signal level by a line specification to be connected.
CONSTITUTION: A line judging part 1 detects to which terminal out of connection terminals 6a-6n provided at every line specification a line is connected, and judges the specification of a connected line from detected connection terminals 6a-6n. An amplification value judging part judges an amplification value to amplify the input signal corresponding to the specification of the line judged by the line judging part 1. An input signal amplifying part 3 amplifies the input signal to a constant signal level fitting in the line specification by the amplification value judged by the amplification value judging part 2.
KAGAWA TETSUYA
SAYAMA KATSUMI
UCHIYAMA HIROKI
