Does a hopping token actually decode? Probe 01 proved the hardware hears ultrasound. This measures whether a detector can read it — per-symbol margin, symbol error rate, and token decode rate against capture time.
Dwell is the experiment. Short dwell = more hops, more null protection, less coherent gain. Long dwell = the reverse. Both phones must be set the same or the listener will never lock.
Loops the token continuously. A 4 kHz control blip sounds once every 8 cycles — audible on purpose, it is what proves the listener's mic path works.
| cycles | capture s | token decode |
|---|---|---|
| no lock yet | ||
Majority vote per symbol position across R cycles. This is the number the product lives on: did the whole token decode, and how long did it take?
| tone | median dB | p10 dB | errors |
|---|---|---|---|
| no lock yet | |||
Margin is measured against the never-emitted guard band (22.5 / 23.0 / 23.5 kHz) using the identical Goertzel window — like-for-like by construction, so it cannot inflate the way Probe 01's peak-hold-vs-mean did. A tone sitting far below its neighbours is a room null, not a broken phone.