Abstract: 1. In a homing torpedo, in combination: means for providing a target search hase of torpedo operation wherein said torpedo is controlled to change depth between predetermined search floor and search ceiling depths and simultaneously controlled to circle in azimuth, whereby to execute helical search action; means for switching, in response to target acquisition at any time during a search phase of torpedo operation, to a target pursuit phase of torpedo operation; and means for switching, in the event of and in response to target loss continuing for a predetermined period in a target pursuit phase, to a modified search phase of torpedo operation wherein said torpedo is initially controlled to execute circle search action while maintaining depth position at substantially that at which target loss occurred, for a predetermined period accommodating at least a complete azimuth circling turn, then controlled to revert to helical search action.

Abstract: 2.

Abstract: A temperature sensor arrangement which utilizes high Q temperature sensitive resonators coupled to an acoustic waveguide. Several resonators, each resonant at a different frequency, are positioned at various locations in a system to be monitored and an acoustic signal is sent down the waveguide. Reflected acoustic energy is examined for the presence of the various resonant frequencies. Since the resonant frequency of each resonator is temperature sensitive, the detected signals provide an indication of temperature at the respective various locations.