Blind Recovery of Hidden Periodic Second-Order Structure in Real Radio-Telescope Baseband Backgrounds: A Frozen-Detector Injection/Recovery Generalization Study.

This study presents a frozen-detector injection/recovery experiment for blind detection of hidden periodic second-order structure in real radio-telescope baseband data. Detector v0.1 was evaluated without retuning across seven independent Arecibo and Green Bank Telescope observations, including ON/OFF targets, a pulsar, and M31. The results demonstrate reproducible recovery of injected OFDM-like temporal structure across heterogeneous real backgrounds while explicitly separating architecture recovery from claims of extraterrestrial or technological origin.