False-state suppression for OFDR via decision-layer continuity judgment

Optical frequency domain reflectometry (OFDR) enables high-spatial-resolution distributed strain sensing based on Rayleigh backscattering. However, local normalized cross-correlation (NCC)-based demodulation can become unreliable when competing correlation peaks lead to high-correlation but spatially inconsistent shift candidates. Such candidates may be incorrectly accepted, introducing false states into the demodulated shift sequence. This paper proposes a rule-based continuity judgment strategy for decision-layer false-state suppression in NCC-based OFDR strain demodulation. The method combines correlation-magnitude gating, spatial-continuity-constrained acceptance, and sequential transition confirmation to prevent isolated false candidates from being directly accepted as the current shift state. Experimental evaluation over a 90 m OFDR sensing range with an effective spatial resolution of 1.290 cm shows that, under the tested 500 μ ε loading condition, the proposed method reduces the abrupt jump count from 523 to 2 relative to unconstrained NCC while preserving the localized strain response. These results indicate that the proposed continuity judgment strategy improves the stability of NCC-based OFDR strain demodulation when high-correlation false candidates occur, without requiring hardware modification or data-driven training.