Echo correlation system for submarine detection using active sounding devices

Claim 3

A system as claimed in claim 1 wherein said N-1 storage means each comprise a further delay device and a memory device, the outputs of said memory devices being connected to an OR circuit whose output forms a said input to said coincidence gate.

Claim 4

A system as claimed in claim 2 wherein said delay devices and said memory devices comprise shift registers whose clock inpuTs are connected to receive the same clock signals.

Claim 5

A system as claimed in claim 1 wherein said first means comprises first and second shift registers each providing a delay of a duration B, and wherein said first storage means of said second means comprises a shift register providing a delay of duration 2 Delta and said N-1 further storage means comprises two further storage means respectively comprising a shift register providing a storage time of duration 2 Delta connected in series with a shift register providing a delay of duration Delta , and a shift register providing a storage time of duration 4 Delta , where Delta 2R/c B, where R is the maximum possible total radial, c is the speed of propagation of sound waves in water and B is the duration of a sweep and the total radial is defined as the algebraic sum of the velocity of the target providing the echoes and the velocity of the sounding device.

Claim 6

A system as claimed in claim 4 wherein a clock frequency, H, is produced by means comprising frequency oscillator for providing clock pulses of a frequency kH, a counter-divider for dividing the output of said oscillator by k and a second counter-divider for dividing by p, where p is the number of stages of the shift registers providing a total delay of duration B.

Claim 7

A system as claimed in claim 1 further comprising a plurality of further coincidence gates, the outputs of said N storage means being connected in all possible combinations taken two at a time to the inputs of said further coincidence gates, and logic circuit means connected to the output of said N-input coincidence gate and to the outputs of said further coincidence gates, said logic circuit being connected to receive a manual command signal and comprising an OR gate, connected to the output thereof, for providing, responsive to a first said command signal, the correlation of N echoes taken together and for providing, responsive to a second said command signal, one of the correlations of N echoes taken two at a time.

Claim 8

A system as claimed in claim 6 wherein said command signal comprises a binary command signal X and said OR gate providing correlation of N echoes taken together for X 1 and one of the correlations of N echoes taken two at a time for X 0.

Claim 9

A system as claimed in claim 3 wherein said N-1 storage means comprise two storage means, each including supplemental shift registers, the delay provided by one of said supplemental shift registers being twice that provided by the other, said supplemental shift registers being controlled by a clock input having a frequency proportional to the speed of the vessel carrying the active sounding device and inversely proportional to the approximate cosine of the angle of the path to the target producing said echoes relative to the forward path of the vessel, said path to the target being taken among the forward paths.

Claim 10

A system as claimed in claim 3 wherein said N-1 storage means comprise two storage means, and wherein a supplemental shift register is connected in series with each said delay device of said first means, said supplemental shift registers providing equal delay relative to each other and being controlled by a clock input having a frequency proportional to the speed of the vessel carrying the active sounding device and inversely proportional to the approximate cosine of the angle of position of the path to the target producing said echoes relative to the aft path of the vessel, said path to the target being taken among the aft paths.