Saw Tooth Bias in Digital Split Beam Trackers

Inaccurate dlpole spacing modeling causes Sawtooth bias in digital split-beam trackers. This paper presents a unified treatment of the generalized dipole spacing model for a complex array and discusses the parametric dependence in detail. The study conducted revealed that in addition to conventional array/beamformer parameters, the dipole spacing depended on "quadrature" angular offset from bore- sight and signal-to-noise ratio. The former resulted from an effective phase shading, induced by discrete beamformer delays. The latter occurred with clipped beamformer and appeared as an amplitude shading induced by the hydrophone beam pattern. The magnitude of these effects varied with signal spectrum.