| Lp [cm] | Direct measurement | FFT [C] (|[A]-[C]|) [sec] | Lin’s regression [D] (|[A]-[D]|) [sec] | |
| at x = 5 cm [A] [sec] | at x = 10 cm [B] [sec] | |||
| 14.5* | 2.83 | 2.81 | 2.84 (0.01) | 3.47 (0.64) |
| 15* | 3.17 | 3.16 | 3.25 (0.08) | 3.60 (0.43) |
| 14.5 | 2.64 | 2.65 | 2.62 (0.02) | 3.47 (0.83) |
| 15 | 2.74 | 2.75 | 2.84 (0.10) | 3.60 (0.86) |
| 16 | 3.23 | 3.17 | 3.25 (0.02) | 3.88 (0.65) |
| 17 | 3.37 | 3.37 | 3.41 (0.04) | 4.17 (0.80) |
| 18 | 3.74 | 3.74 | 3.79 (0.05) | 4.50 (0.76) |
| 19 | 4.76 | 4.73 | 4.71 (0.05) | 4.86 (0.10) |
| 20 | 5.36 | 5.41 | 5.68 (0.32) | 5.26 (0.10) |
| 20.5 | 5.89 | 5.78 | 5.93 (0.04) | 5.48 (0.41) |