Abstract: A target simulator system that may be suspended in the ocean to simulate a oving target to a homing weapon. The system includes a receiving transducer for receiving an acoustic signal transmitted by the homing weapon. The acoustic signal is then amplified, doppler shifted, filtered and then retransmitted by a transmitting transducer to the homing weapon. The doppler shift may be selected to have the retransmitted signal simulate a target that is moving towards or away from the homing weapon. The system includes a power compensating circuit and a monitor circuit to assure that the target simulator system is operating within acceptable amplification limits.