Relationships among Vernier-method and other direction-of-arrival estimators

Interferometry is a powerful method to estimate direction of arrival (DOA) in seafloor mapping. Its main difficulty derives from a 2π-ambiguity in phase, complicated by the presence of noise. Here, the Vernier method is explained and its performance is analyzed. This performance is compared against that of three other DOA estimators, namely the multiple signal classification (MUSIC) algorithm and two maximum likelihood estimators (MLEs) for real data derived from measurements with a dual-baseline sidescan sonar operating at 455 kHz. It is shown that the performance of all four estimators is impacted by a quantity that is treated explicitly within the Vernier method.