During the Phase II project of NSRL, a turn by turn BPM (Beam Position Monitor) system is proposed for storage ring diagnostics which engages log-ratio electronics circuit to measure machine properties of the HLS (Hefei Light Source) storage ring. The log-ratio processor works at 408MHz, twice the RF frequency of HLS. Modern logarithmic amplifiers with wide dynamic range, great bandwidth, good logarithmic conformance, and low cost are attractive for beam position measurements. Injection kicker and the stripline-electrode resonant exciting methods are used to excite beam for nonlinear beam dynamics and phase space studies of stored beam. Up to 2 seconds of data acquisition is ensured. In this paper we present the performance of each component and preliminary test results of the turn-by-turn BPM system.