Gl. Jin et Dj. Tang, UNCERTAINTIES OF DIFFERENTIAL PHASE ESTIMATION ASSOCIATED WITH INTERFEROMETRIC SONARS, IEEE journal of oceanic engineering, 21(1), 1996, pp. 53-63
The differential phase technique has been widely used in various sonar
systems; however, uncertainties associated with the estimation of sca
tterer depths are not completely understood, Numerical simulations for
multiple bottom scatterers are performed, and they show that the unce
rtainties of depth measurements, in the absence of noise interferences
, are much greater than the amount explainable by the uncertainty asso
ciated with the signal-arrival-angle within an instantaneous insonifie
d area, The cause of the excess deviation is analyzed, particularly fo
r the two-scatterer case, This kind of error is referred to as ''basel
ine decorrelation'' which is related to the speckle phenomena and can
be considered as an equivalent noise source, Experimental data obtaine
d by a particular high-frequency (40 kHz) interferometric system, the
Benthic Acoustic Measurement System (BAMS) developed by the Applied Ph
ysics Laboratory, University of Washington, at a hat sandy bottom off
the coast of Panama City, FL, were analyzed, Both analytical formulas
and a numerical model are given to estimate the measurement uncertaint
y caused by the baseline decorrelation, as well as noise interferences
based on the parameters of the BAMS, in order to understand uncertain
ties of the differential phase estimation, It is found that baseline d
ecorrelation is the main source of error for the BAMS for grazing angl
es greater than 12 degrees, The measurement uncertainties at this graz
ing angle interval are in agreement with the theoretical predictions.