Abstract: A monitor for a communication system injects a shaped pulse into the communication system at a first point. The shaped pulse has a short time duration to enable the integrity of the communication system to be monitored in a short amount of time. The shaped pulse also has a narrow frequency spectrum to avoid interference with live signals present in the communication system. The monitor includes a source generating a carrier signal having an adjustable frequency, a modulator receiving the carrier signal and modulating the carrier signal to provide the shaped pulse. Alternatively, the monitor includes a signal source directly providing the shaped pulse. A receiver within the monitor detects the shaped pulse at one or more second points in the communication system. The shaped pulse is below live signals within the communication system by a predesignated threshold at a predetermined frequency offset from the frequency of the carrier signal.