Frequency Envelope Traversal — A Progressive Experimental Validation Programme

This paper presents a progressive experimental validation programme for Frequency Envelope Traversal (FET), a continuity-based navigation framework developed within the Paton System. The programme translates the conceptual FET architecture into a staged and falsifiable engineering pathway. It begins with recorded-flight replay and mathematical reconstruction, progresses through hardware-in-the-loop testing and environmental qualification, and then advances toward passive sounding-rocket payload testing, limited active control, three-axis orientation control, independent free-flying sub-payload trials, and a propelled CubeSat orbital demonstration. The proposed architecture combines an Internal Reference Structure, environmental sensing, Frequency Envelope construction, compatibility and coherence assessment, admissibility gating, corrective-demand estimation, and traversal selection. FET does not introduce new physical forces, speculative propulsion or replacement dynamics. Propulsion, flight mechanics and environmental interactions remain governed by established physics. The proposed contribution lies in the decision architecture through which a vehicle evaluates whether its current configuration remains compatible with its changing environment and whether another admissible configuration may preserve smoother continuation with reduced corrective demand. The programme deliberately separates passive observation, calculated recommendation and active intervention. Early stages permit FET to operate without controlling the host vehicle, allowing its outputs to be compared against recorded vehicle behaviour and conventional navigation systems before any control authority is introduced. The paper defines the required sensing, processing, logging, telemetry, power, safety and experimental comparison architecture for each stage. It also establishes measurable success and failure conditions, including timing performance, state-estimation accuracy, admissibility compliance, correction demand, energy use, orientation stability and safe reversion to conventional operation. The result is a progressive technical pathway through which FET may be investigated without requiring immediate full-scale vehicle construction or unsupported claims of performance.