Continuous transmission synthetic aperture sonar.

摘要

A synthetic aperture side scan sonar using continuous instead of pulsed transmission. The transmission is frequency coded to determine range. A continuous transmission frequency modulation (CTFM) sonar (4, 20) transmits and receives continuously as it moves underwater along a track at right angles to the transmitted sonar beam. The echoes received are demodulated by the sonar (4, 20) to produce a collection of frequencies with different phases at baseband where the value of the frequency represents the range of each echo producing underwater target. This spectral information is recorded on a tape recorder (6) as the sonar moves along a defined track. The tape recording is subsequently played back and the phase and amplitude information of the demodulated echoes is processed by a computer (7, 22) which produces an underwater map on a graphics printer (46) which appears to have been produced from a sonar having an aperture approximately the length of the underwater track traversed by the sonar.