Abstract: An automatic attenuator for use in Sonobuoy Missile Impact Location System (SMILS) sonobuoys to separate re-entry which impact signatures from other acoustic phenomena is disclosed. The attenuator for the sonobuoy device is divided into a high gain, narrow band channel for detection of ping signals and a low gain, wide band channel for detection of impact signals. The output of the two channels are summed in a summing amplifier. A switch is provided to turn off the high gain channel whenever received signals are large enough to cause a comparator circuit to activate a time which turns off the switch for 15 seconds time. Thus, the stronger impact signals are distinguished from other random signals.

Abstract: 1. A fuze for exploding projectiles and the like in proximity to a target, omprising, means for generating radio frequency waves, means for propagating said generated waves through the space intervening between the projectile and the target, a portion of said propagated waves being reflected back by said target toward said propagation means, means connected to said propagation means for simultaneously detecting said generated waves and said reflected waves to provide a signal for firing said fuze, said detecting means being sensitive to said reflected waves only in the presence of said generated waves, a variable impedance connected to said wave generating means, and means for varying said impedance from a relatively high value to a relatively low value thereby terminating the operation of said wave generating means to render said detecting means insensitive both to reflected waves and to spurious waves.

Abstract: 1. A radio proximity fuze comprising, an oscillator for generating radio quency waves, an antenna for propagating said generated waves through space and for receiving waves reflected from a target and propagated through space toward said antenna, a detector for rectifying said generated waves and said received waves, an output connection to said detector for utilizing the detector output to fire said fuze, means for periodically supplying power to said radio frequency oscillator, said power means including a thyratron relaxation oscillator and a connection from said relaxation oscillator to said radio frequency oscillator, and means for rendering said detector insensitive to received waves during periods of non-operation of said oscillator whereby said fuze is afforded protection against jamming by remotely situated radio transmitters.