Fig. 15

Comparisons of estimated phase velocities obtained through DSPAC method with those obtained through conventional methods in case of noise-free synthetic data. The array shape is the most-flattened triangle (R1-R6-R7), except for “FK (6 RCVRs)”. The legend is the same as that in Fig. 12. The DSPAC method is applied for two types of the termination of series expansion, such as terms until \(n=1\) (shown as \(J_2\)) and \(n=2\) (shown as \(J_4\)). Only the DSPAC (\(J_4\)) method provides a good estimation in the wide frequency range. To avoid spatial aliasing in the analysis of the FK method, we searched over a limited range of phase velocities, which resulted in the misalignment with the target value in the frequency range above 12 Hz.