PARTIAL FIELD DECOMPOSITION IN NEARFIELD ACOUSTICAL HOLOGRAPHY BY THE USE OF SINGULAR VALUE DECOMPOSITION AND PARTIAL COHERENCE PROCEDURES

摘要

The nearfield acoustical holography procedure requires the identification of coherent hologram data. Thisprocedure thus requires that a partially coherent field which is generated by several incoherent noise sourcesoperating simultaneously should first be decomposed into a set of coherent partial fields. Here, decompositiontheory was investigated, and the derivation of the relevant equations was presented in detail. It was suggested thatan eigen analysis be. used to determine the number cf sources and thus the number of reference signals required.The reference selection procedure was based on the MUSIC algorithm. Also, conventional decomposition methodssuch as SVD and partial coherence were investigated and compared. To mitigate their drawbacks, a new residualdecomposition method was introduced and was shown to he successful.