This research proposes a carrier recovery method for subcarrier-coded backscatter links using a fractional, less than one-symbol, delayed detection. The fractional delayed detection extends the permissible subcarrier frequency errors, but results in an unbalanced distribution of delayed symbols. This paper reveals the contribution of the fractional detection in RFID sensing system, particularly the system with a FDMA backscatter to collect streaming data. The unbalanced symbol distribution problem is resolved using a principal component analysis (PCA) of delayed symbols. The fractional delayed detection was evaluated both with a MATLAB simulation, and a combination of a soft-ware defined interrogator and a prototype wireless sensor. Both evaluations showed the effectiveness of the proposal.