GB1330351A

GB1330351A - Sonar systems

Info

Publication number: GB1330351A
Authority: GB
Original assignee: British Aircraft Corp Ltd
Current assignee: British Aircraft Corp Ltd
Priority date: 1971-09-15
Filing date: 1971-09-15
Publication date: 1973-09-19

Abstract

1330351 Sonar apparatus BRITISH AIRCRAFT CORP Ltd 15 Sept 1971 [15 Sept 1970] 44073/70 Heading H4D Sonar pulses are transmitted by energizing from a single source a line of transducers with a phase difference between successive transducers to produce a narrow beam pulse wherein the phase differences are varied for each pulse to swing the beam across a wider sector. In a ship mounted sonar system the transducer array comprises nine horizontal strips containing sixtyfour transducers. In each strip the transducers are energized at a prf which is varied to swing the beam in azimuth and the relative timing of the energization of each strip moves the beam in elevation. Unit 10 receives inputs at the transmitter prf (1 Hz) and the beam stepping frequency (5 KHz) and produces an azimuth demand signal at the transmitter prf which comprises sixty six-bit digital words each word corresponding to a particular azimuth appearing at the beam stepping frequency. A left/right command signal is also produced which commands the transducers to be energized in the opposite direction after one-half of the required sector has been swept out-thus enabling a smaller range of phase differences to be utilized. In the unit 12 a counter is started at a time selected by the required beam elevation and the counter output is compared with the instantaneous azimuth demand. At equality a comparator produces a pulse which resets the counter and advances a six-bit counter. Thus the six-bit counter is clocked at a frequency dependent on the azimuth demand. The six-bit counter output is passed to a gate control which specifies the direction in which the transducers are to be energized. The gate control output is passed to the transducer drive circuits which decode the output and fire each transducer in turn, the repetition rate being dependent on the azimuth demand. As the unit 10 changes the azimuth demand, the rate and direction of energizing the transducers is varied to sweep the beam across the required sector.