Abstract—The newly released Distributed System Interface 3 (DSI3) Bus Standard specification defines 3 modulation levels form which 16 valid symbols are coded. This complex structure is best decoded with symbol pattern recognition. In order to simplify the pattern recognition correlation calculation, the received differential current is quantized back to 3 levels. This paper describes how the thresholds are estimated and adapted for the most optimum quantization. The complete system was simulated in Matlab script. It will be shown that after 24 symbols, the estimated threshold is 6% away from the optimum thresholds when the initial currents are 35% off the expected nominal thresholds. This proves fast convergence to the optimal threshold and a small residual error in a system that includes the major distortions and inaccuracies.