On the basis of the analysis of the depolarization effect of Polarization Mode Dispersion(PMD) on the measurement of the polarization-nulling method
a simple configuration that provides OSNR information using polarization scrambling and orthogonal polarization detection is proposed and demonstrated.The polarization scrambler that can scramble the input polarization state to cover the Poincare sphere is shared by many Wavelength Division Multiplexing(WDM) channels.After the demultiplexer
the desired channel will be split into two arms using a Polarization Beam Splitter(PBS) and OSNR are obtained from interaction terms between two orthogonal polarization arms.The veracity of the improved scheme is verified by simulation.