US 4,939,700 AGranted

Bathymetry using computational algorithm field and background of the invention

OwnerJ. Raymond Bretoninventor

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Abstract

A method and apparatus steers the returning beams of a receiver in a swath bathymetric system to an actual target based on prior steering angle information for the target and using an algorithm which demonstrates a linear relationship between the phase of the return beam and the steering angle therefor. The receiver comprises a plurality of transducing elements which each emit a signal. The array is divided into two groups of elements which are processed and combined to form beams for each group which are steered to the known steering angle for the target. Beams are then steered to a slightly offset angle to produce an offset beam. Using an equation to define each return beam according to phase and error between prior known and actual steering angles for the target, the error value can be reduced to zero to provide an accurate measurement of the actual steering angle for the target.

Claims7

Dependent claims

In a method of steering a return beam of receiver, to a target, the receiver receiving reflected energy from the target which has been illuminated by a transmitted beam of energy which is narrower in a first direction than in a second direction, the return beam being wider in the first direction than in the second direction, the receiver having a plurality of transmitting elements lying in an array extending in the second direction, and wherein a prior steering angle for the target is known, the improvement comprising a method of estimating the actual steering angle for the target comprising:

dividing the array into at least two parts for producing two groups of transducing element signals;
combining and processing the signals of each group to steer each group to the known prior steering angle to form an initial beam for each group;
measuring the phase of the initial beam for each group;
combining and processing the signal of each group to steer each group by a known offset angle from the known prior steering angle to form an offset beam for each group;
the phase of the initial and offset beams changing in a linear fashion with an error difference between an actual steering angle from the target and the known prior steering angle for the target;
and
finding an intersection of lines formed by plotting phase versus the error difference to find the phase at which the error difference is zero which represents an estimate of the actual steering angle for the target.

4 more elements

Dependencies are inferred from the claim text.