Patent ID: 6825714
Filing Date: 2004-11-30
Classification: G01D,H04J,H04L

Abstract:
Apparatus for reducing sign uncertainty in a coherent phase generated carrier demodulator in an interferometric acoustic sensor system, comprising:an optical signal source that provides a phase generated carrier signal to the interferometric acoustic sensor system so that the multi-channel acoustic sensor system produces an acoustic signal that is superimposed on the phase generated carrier signal, the interferometric acoustic sensor system being arranged to provide an optical signal output that includes the phase generated carrier signal and the acoustic signal; a photodetector arranged to receive the optical signal output from the interferometric acoustic sensor system; a downconverter connected to the photodetector, the downconverter being arranged to separate an in-phase component I and a quadrature component Q of the acoustic signal from the phase generated carrier signal; and a coordinate transformer connected to the downconverter, the coordinate transformer being arranged to function as a rectangular to polar converter and provide signals indicative of a polar phase angle between the in-phase component I and the quadrature phase component Q of the acoustic signal.