Signal limiting circuit

摘要

The disclosed signal limiting circuit is bridged on to a bidirectional communication path (T, R) and functions to selectively attenuate excessive signals (2VA) being transmitted in a predetermined direction on the bidirectional communication path. This is accomplished by a signal discriminator circuit (100) which separates the excessive signal (2VA) from the plurality of signals appearing on the communication path (T, R). The signal discriminator circuit (100) also inverts the isolated excessive signal, passes it through an attenuator (102) to a signal injection circuit (103) which injects a controlled amount of the 180 degrees out-of-phase isolated excessive signal back on the communication path (T, R) to cancel out a portion of the excessive signal, thereby providing selective attenuation of the excessive signal.