bk4819_eval_receiver reports RSSI above any sane squelch threshold on every poll, and
a scan halts when it finds a busy channel -- so the S-meter work could plausibly have
stopped scanning dead on its first step. Measured: it does not, 6 distinct tunings
over 6 samples.
The check compares the framebuffer rows holding the frequency digits rather than
counting distinct frames. Frame comparison would pass on a completely parked radio,
because RSSI varies every poll and the meter redraws constantly -- an initial run
scored 8/8 distinct frames and proved nothing. Narrowing to pages 1-2 answers the
actual question: did the radio retune.
Incidentally established that page 4 is not the meter row: it was byte-identical
across all six samples while the frequency changed.
