US 4,794,574 AGranted

Broad band interference sonar having compressed emission

AssigneeThomson-CSF

InventorGeorges Grall

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Abstract

A system of emission array with several pairs of emitting transducers to emit simultaneously and covering contiguous frequency sub-bands of a band B. The sub-bands have a width which is less than or at most equal to the width inducing an acceptable displacement of the directivity lobes of the emission pattern of a pair of arrays. The emitters of a single pair are spaced by a distance of L.sub.i and emit signal pulses at frequency f.sub.i and of duration .tau..sub.e 1/.DELTA.f, the products L.sub.i f.sub.i being equal for all the pairs of emitters. The emission patterns of the various pairs of emitters accordingly coincide precisely, and, as the emitters are supplied with signals emerging from the oscillators which are in phase at the center of the pulse of duration .tau..sub.e, the pulse resulting from the superposition of the emitted signals is compressed in time.

Claims8

Dependent claims

A broad band interference sonar transducer array exhibiting compressed emission, comprising an emission system having two spaced emitters associated with emission control circuits and a reception system associated with reception circuits, wherein each emitter is constituted by a group of N pairs of elementary emitters (E.sub.1).sub.i and (E.sub.2).sub.i, where i is an integer between -(N-1)/2 and (N-1)/2 for odd N and i is between -N/2 and + N/2 and different from O for even N, one elementary emitter (E.sub.1).sub.i being spaced from the corresponding elementary emitter (E.sub.2).sub.i by a length L.sub.i, these two elementary emitters including means for supplying a common signal of frequency f.sub.i, wherein the products L.sub.i f.sub.i of the N pairs of elementary emitters defined in this manner are equal, and wherein all the emitters are supplied simultaneously, during recurrent pulses, with signals of frequencies f.sub.i in phase at the center of the pulses.

Dependencies are inferred from the claim text.