The invention relates to a strong-robustness minimum-variance
ultrasonic beam forming method based on subspace
oblique projection, and belongs to the technical field of
ultrasonic imaging. The method comprises the following steps: performing spatial
smoothing and
diagonal loading
processing on echo signals received by an ultrasonic array to obtain a sample
covariance matrix, decomposing the characteristics of the sample
covariance matrix into a
signal subspace and an interference
noise subspace, and constructing a transition matrix according to characteristic vectors of the
signal subspace and corresponding characteristic values; calculating an
oblique projection operator in combination with the expected
direction vector and a pseudo-inverse matrix of the transition matrix, and projecting a weight obtained by minimum variance beam forming into a
signal subspace in which the expected
direction vector is located along a direction parallel to the interference
noise direction matrix by using the
oblique projection operator to obtain a new weight; performing weighted summation on the ultrasonic array echo signals by using the new weight to obtain a final adaptive beam forming signal; according to the method, the
algorithm robustness can be remarkably enhanced, the
image resolution is maintained,
background noise is suppressed, and the
ultrasonic imaging quality is improved on the whole.