Electronic sector scanning

A system of scanning, or swinging, the beam of an acoustic receiver by electronic means, while the transducer itself remains stationary, is described. The scanning may be very rapid, so that in a pulse echo-ranging system (e.g. asdic) the whole scanned sector may be covered within the duration of a pulse, giving effectively simultaneous reception over a sector which is shown to be approximately n times the 3-db width of the beam itself, n being the number of sections into which the array is divided. The more critical details of the design are discussed, and experimental results are given to confirm the theoretical analysis.