Rather, I don't think the data channel was actually down-shifted, but that it wasn't filtered out (probably due to a broken analog filtering circuit after the fall), so it was still outside of the audible spectrum but available to the sound card and hence visible in her software spectrum analyzer. It also sounded like she was seeing some aliasing effect, i.e. that the data signal was probably out of band for the sound card ADC, but "folded" down into the sampler frequency range due to Nyquist folding "magic" (which is maybe what you meant with "down-shifting", now that I think about it?).
sriram_malhar|1 year ago