The influence of parameters measurement error on demodulation performance of PGC arctangent algorithm in optical fiber hydrophone

Abstract

ABSTRACT The phase generated carrier (PGC) arctangent algorithm needs to be compensated when the carrier modulation depth C deviates from 2.63 rad. Parameters measurement error can induce an incomplete compensation in the arctangent algorithm. The demodulation distortion due to parameters esti mation error is analyzed quantitatively in this paper. The relative amplitude error (RAE) and harmonic suppression ratio (HSR) are considered, which indicate a linear distortion and a nonlinear one separately. Theoretical analysis shows that the fluctuation ra nge of RAE has a linear relation with an absolute value of / C which is the estimation error of the modulation depth C . The fluctuation range of RAE also has a square relation with / o1 , / o2 which are the estimation error of the phase delay ' o 1 ' o 2 of fundamental and second harmonic carriers respectively. Similarly, minimum HSR decr eases by 6dB along with a doubled absolute value of / C and by 12dB with that of / o1 . Experimental results are presented to corroborate the theory. Keywords: optical fiber hydrophone, phase generated carrier(PGC), arctangent demodulation algorithm , relative amplitude error(RAE), harmonic suppression ratio(HSR),modulation depth, carrier phase delay, parameter estimation