★ This program has added a failure case in anchor cable detection on June 1, 2018: 2 times of excitation
3.4.4 Failure case in anchor cable detection: 2 excitations
In the anchor cable detection, whether it is a manual or a mechanical or electromagnetic excitation device without a reaction device, it is easy to generate two excitations, resulting in completely erroneous detection results. The following picture shows some typical 2 excitation cases:
Figure 3-4-7 More obvious two-time excitation field test case diagram
The signal of 2 excitations has the following characteristics:
(1) The signal quality is very good, while the real reflected signal is often weak. It is precisely this point that is most deceptive and deceptive;
(2) The signal is very similar to the first excitation signal and also contains more high frequency components. However, due to the dispersion of the true reflected signal, the similarity with the excitation signal is lower, especially the high frequency component is less;
(3) The position of each signal is different. Since the interval between the two excitations is affected by many factors, it is not a fixed value, and the time of the real reflection signal is basically the same. Therefore, this feature is the most effective way to discern whether it is 2 excitations.