I recently doing ultrasonic signal detection, the use of ultrasound probe to detect ultrasonic signal, met a seemingly very simple, but the phenomenon of troubling things
, card for a long time failed to solve, ask almighty god to the younger brother, Thanks! 
1, the scanning process
Sound source at the center of the scanning area, probe scanning to the other side, from one side of regional centres range 6 mm step (step length 50 microns, 120), as shown in figure 1:
2, question
Normally, the acquired signal (1) voltage amplitude should be driven by the changing process of weak, strong, weak, (2) signal in time (delay time) should be driven by long - short - long change process, clear, something strange happened: 1) no problem, (2) the change of signal delay time is monotone linear increase,
: the speak in figure 2 is the 60th columns of seven scanning signal:
Figure 3 for 60 all signal delay time on line diagram:
According to the normal logic, figure 3 curve should be close to the letter "V" shape,
Experiments confirm that the signal is the ultrasonic signal (distance calculated by the delay time is consistent with the actual probe to the acoustic source),
In the heart calls everyone a great god, may be where there is a problem, or what validation can also do? The younger brother grateful grateful!
