There are many reasons for undetected defect such as unsuitable parameter selection of probe, the influence of interference wave and the unclear judgment of defect echo and burr echo.

The paper discusses the defect echo feature when applying different K value s probe detects different depth artificial reflectors in ultrasonic detection,and makes comparison among them,thus puts forward the significance of applying different K value probe on different detected parts,meanwhile it provides theoretical basis for practical detection work.

Reduction of noise in flaw signals based on independent component analysis;

In order to detect pipeline by technology of magnetic flux leakage testing it is necessary to analysis flaw signal.

A method combined with global and dynamic threshold image segmentation is proposed,and by which weak defect regions in the ultrasonic C-scan image of Cu-steel surfacing are segmented effectively.

Application of wavelet analysis in echo signal processing of the laser rapid scanning;

The result shows that in order to obtain the strong echo signal,a suitable selection of the ultrasonic transducer operating frequency is necessary.

Then the waveform design principle and the echo signal process in practice application are given.