Table 7.

Comparison of DoA (in degrees) estimation performance between two designed arrays (Figure 5) for measurements affected by a coherent edge reflection due to an IS (see the $I{S}_1$ in the Figure 10), and a incoherent spurious signal due to a second IS of a previous impact/defect with a random DoA within the range [169–180] (see the $I{S}_2$ in the Figure 10). AS and ISs band: [30–40] [kHz]; (Impact distance d = 40 [cm]; Cluster distance from the edge $d_c$ = 17 [cm]; Structure length $l_s$ = 1.1 [m]).

			Disks	DCSs				Disks	DCSs
			GM-GCC	GM-GCC				GM-GCC	GM-GCC
AS DoA	IS DoA	IS-2 DoA	Estimated DoA	Estimated DoA	AS DoA	IS DoA	IS-2 DOA	Estimated DoA	Estimated DoA
0	180	178	16.66	−2.03	50	160.27	171	69.3	49.85
5	178.24	179	7.62	5.42	55	157.7	179	28.44	58.49
10	176.48	171	17.76	10.07	60	154.91	179	116.24	58.91
15	174.68	179	32.01	15.4	65	151.87	175	20.26	68
20	172.86	176	29.71	20.23	70	148.51	178	83.38	73.16
25	170.98	171	30.2	25.38	75	144.77	171	83.52	73.62
30	169.04	172	23.41	28.9	80	140.56	174	27.38	81.15
35	167.02	175	25.85	34.42	85	135.8	179	17.65	79.78
40	164.9	179	61.1	40.15	90	130.36	178	110.89	92.33
45	162.66	179	92.82	46.87	-	-		SD 31.49 ME 67.35	SD 2.03 ME 5.22