Thomson Marconi Sonar, S.a.s.

Marc Pinto

A method of readjusting sonar images using sub-antennae. For each point of the bottom, a sub-antenna is constructed of a given size at one end of the physical antenna. A first channel is constructed over a short time slice centered on the point. A sub-antenna is also constructed upon recurrence No. 2 of the same size as the first one, but at the opposite end of the physical antenna. With the second sub-antenna, a plurality of second channels is formed over a sector which is sufficiently wide to contain the point. These second channels are intercorrelated with the first channel so as to adopt the one which maximizes the intercorrelation peak. This procedure is repeated for different sub-antenna sizes and one is adopted which produces the maximum of the preceding intercorrelations. The best estimate of the position of the point in the second sonar image is deduced from the azimuth shifts between the first channel and the best second channel, from the intercorrelation delay between these channels and from the best sub-antenna size.

Method of resetting sonar images using secondary antenna

A synthetic-antenna side sonar device. Two transmission transducers which operate in interferrometric mode are fixed to the two ends of a physical antenna of a sonar. The forward speed of the sonar is chosen so that the zeros of the physical reception antenna coincide with one out of two of the side lobes of the radiation diagram of the synthetic antenna. Also the speed is chosen so that the zeros of the physical diagram of the interferrometric transmission antenna coincide with the other side lobes. This arrangement increases the range and thus the hourly coverage of a sonar for a given speed.

Growing community of inventors

Brest, France

Marc Pinto