Multispectral UCA: Frequency-Division for Simultaneous 1/f Channels

We extend the UCA encoder (Beyer 2026f/g) with multispectral capability: multiple simultaneous messages in orthogonal frequency bands, each preserving the global 1/f amplitude profile. Four findings: (1) deep frequency bands are more robust due to higher 1/f amplitude; (2) optimal band count is 4–8 for capacity-robustness trade-off; (3) priority encoding possible — critical messages in deep bands; (4) telecom audio fix: shift carriers into bandpass range (891–10105 bins). Multispectral preserves C≈0.745 globally and is the natural FDM extension of the AU principle.