Acoustic imaging system

Claim 1

An acoustic imaging system comprising: a transmission rectangular array of M transmitting transducers such as E K , where 1≦k≦M; a receiving rectangular array having N lines of P hydrophones H i ,j, where 1≦i≦P and 1≦j≦N, said lines being parallel to the lines of said transmission array of M transmitting transducers, the distances between adjacent hydrophones in the lines and in the columns being respectively d 1 and d 2 , wherein the distances between adjacent said transmitting transducers are Nd 1 and Pd 2 respectively in the lines and in the columns in said transmission rectangular array; energizing circuit means for energizing said transmitting transducers by supplying code modulated signals with the same central frequency, each said transmitting transducer E k transmitting with a different code, said codes being orthogonal one to the other; M processing circuits receiving the output of said hydrophones and including a correlation means receiving and decoding said code modulated signals in order to provide decoded signals and outputting signals X i ,jl, . . . X i ,j,k, . . . X i ,j,M and Y i ,j,l . . . Y i ,j,k, . . . Y i ,j,m for respectively the real and imaginary components of each of said decoded signals ; multiplexing means for receiving said decoded signals and multiplexing separately said real and imaginary components, and providing a multiplexing sequence of signals corresponding to the signals of a hydrophone line j in succession, for the transmitters of the same line 1; and a carrier being supplied with said multiplexing sequences of signals and outputting signals U j ,i which are applied to a two-dimensional Fourier transform analog device.