ABSTRACT
Itisalsoofinteresttodeterminetheestimatedvelocitiesandazimuths andtheiruncertaintiesunderthecoherencestructureestimatedatthearray. ThisrequiresestimatingthevarianceofthebeamformedestimatormaximizingB(9)undertheassumptionthatthereislessthanperfectcoherence usingEq.(36).Thiscanbecomparedtothevarianceofgeneralizedbeam maximizingGB(9),givenbyEq.(32).Bothequationsrequireestimatingthe NxNsignalspectralmatrix(;(v)andthenoisespectrumP11 (v).Inthecase ofthe0maximizingthebeamformingestimator,weusedEqns(51)-(53) andtheEMstepsIto5toobtainthemaximumlikelihoodestimatorsfor f~(v)andP11 (v),withfixedat0.Forthecaseof0".themaximizerofthe generalbeam,wesimplyusedtheECMalgorithm,followingSteps1-7as given.Figure5showstheresultsusingaslightlybroaderband(L=19)and wenotethattheestimatorsandtheirstandarderrorsarenearlythesame,a reflection,nodoubtoftherelativelyhighempiricalcoherencebetweenthe threesensorsinthiscase.
