A Low-Cost Wireless Multinode Vibration Monitoring System for Civil Structures

Table 1

Natural frequencies identified from the impulse vibration test.

System		Natural frequency (Hz)			Relative difference to high-grade system (%)
		1st mode	2nd mode	3rd mode	1st mode	2nd mode	3rd mode
High-grade		3.516	15.283	23.486		—	—
Low-cost	No interpolation	3.313	14.544	22.256	5.77%	4.84%	5.24%
	Linear	3.394	Not found	Not found	3.47%	—	—
	Spline	3.459	15.137	23.071	1.62%	0.96%	1.77%
	MAkima	3.459	15.137	23.071	1.62%	0.96%	1.77%
	NUFFT	3.459	15.137	23.031	1.62%	0.96%	1.94%

Frequencies marked with ^∗ are associated to modes identified with a manual peak selection.