Noninvasive Remote Sensing Techniques for Infrastructures Diagnostics

Table 4

Oscillation frequencies of the beam under the four direct impacts measured by Ground-based microwave radar interferometer.

Drop	First frequency (Hz)	Secondary frequency (Hz)
1	1.6	4.8
2	1.6	4.6
3	1.4	4.5
4	1.4	3.8