3 results about "Coherence factor" patented technology

This invention discloses a multi-echo detection method for a multi-beam echo sounding system with combined amplitude and phase features. The pre-detection step includes: segmenting the beam output signal; for each unit to be detected, obtaining an amplitude detection threshold using the unit average constant false alarm rate (CFAR) method based on background noise estimation from the reference units on the left and right sides; extracting the instantaneous phase from the signals of each receiving channel using Hilbert transform, and obtaining the phase coherence factor between each receiving channel from statistical characteristics; dynamically adjusting the amplitude detection threshold as an adaptive weight to construct a detection threshold for combined amplitude and phase features; initializing weighting coefficients based on echo intensity differences, and dynamically optimizing them in conjunction with the intensity value of the phase coherence factor to obtain an adaptive weighted amplitude and phase joint detection threshold; merging sampling points exceeding the adaptive weighted amplitude and phase joint detection threshold, removing interfering targets, and identifying and extracting multiple independent effective target intervals.

The application discloses an improved ultrasonic imaging method based on subarray coherence post-filtering, which comprises the following steps: 1. transmitting ultrasonic waves to an imaging area and recording echo signals reflected back; 2. performing delay and superposition processing on the echo signals in a receiving aperture to obtain an imaging vector; 3. calculating a coherence factor, a normalized amplitude standard deviation reciprocal and a subarray length based on the imaging vector; 4. calculating a covariance matrix based on the imaging vector and the subarray length; 5. calculating a weight vector in a feature space-based minimum variance beamformer based on the covariance matrix; 6. calculating a subarray zero-crossing coherence factor based on the imaging vector; 7. calculating a post-filtering result based on adaptive subarray coherence; and 8. multiplying the post-filtering result with a superposition result of the imaging vector and imaging. The application can improve the contrast and resolution of an image.

The invention relates to a non-linear compression and signal-to-noise ratio adaptive weighting full-focusing imaging method and device in the technical field of ultrasonic nondestructive testing. The full-focus ultrasonic imaging method comprises the following steps: calculating a delay correction signal Sij (x, z) of a focus point poi (x, z) on an imaging plane P; carrying out nonlinear transformation on Sij (x, z) through a symbol-reserved p-power root compression operator to obtain a compressed delay correction signal, and carrying out coherent superposition on the compressed delay correction signal to obtain a full focusing intensity value of poi (x, z); calculating a coherence factor CF (x, z) of poi (x, z); and constructing a pixel local area by taking poi (x, z) as a center, and calculating a signal-to-noise ratio SNRlocal (x, z). According to the method, a symbol-reserved nonlinear compression operator is introduced, and a dual optimization strategy of coherence factors and local SNR adaptive weighting is combined, so that effective reflection echoes are enhanced on the basis of improving signal coherence, structural noise can be effectively suppressed, and meanwhile, the integrity of defect signals can be kept; the detection sensitivity and the imaging quality of tiny defects in the coarse grain material are obviously improved.