arXiv:2611.06192v1 Announce Type: new Abstract: Accurate likelihood-ratio (LR) construction is challenging when clutter statistics are unknown. Prespecified clutter models may not adequately describe the observed data, and evaluating target-present densities may require computationally expensive marginalization. This paper proposes a data-driven LR construction framework based on a Bernstein polynomial model (BPM) and a Bernstein induction operator (BIO). The BPM weights are estimated from clutter-only samples, whereas the target-induced responses of the Bernstein basis densities are approximated offline in the same basis to construct column-stochastic matrices. These matrices map clutter-density weights to target-present density weights at specified signal-to-clutter ratios (SCRs), and mixtures of the matrices account for target fluctuations. For a fixed target model and basis representation, the matrix library is independent of the clutter-density weights and can be reused across clutter distributions. The resulting LR construction avoids repeated online evaluation of the physical-induction integrals. Simulations under analytical clutter models show close agreement with the reference LRs and detection probabilities, with lower online computation times in the non-Gaussian cases considered. Experiments using synthetic target echoes embedded in measured sea clutter further show improved detection probabilities relative to the evaluated baselines in the weak-target regime.