Von Mises/Tikhonov-based distributions for systems with differential phase measurement

The von Mises/Tikhonov probability density function (pdf) is examined to use as an approximation for the differential phase in presence of Gaussian noise in systems with differential phase measurement (DPM). It is shown that this approximation is the best fit for the phase difference between two vectors with equal signal-to-noise ratios (SNRs). The strategy is proposed to derive the approximate pdf for the case of infinite SNR in one of the vectors. Two approximating pdfs are derived for the differential phase diversity with different and equal SNRs. An application is given for the error probability in passive wireless remote SAW sensing with DPM.