Alternating current supply line and current carrier modem coupling device for digital data transmission system, has band-pass filter connected between modem and amplifier circuit for passing filtered output signal to circuit

摘要

The device has an isolating transformer (7) whose two windings are connected to a power supply line (8) and a transmission signal injecting circuit, respectively. The circuit has a band-pass filter (12) connected to a transmission output terminal (2) of a modem (1), where an output signal of the filter passes to an amplifier circuit (13) that is connected to a hot point of one winding of the transformer.