If you're hearing IBOC on 770, try LSB. It LSB is louder than USB, the
the IBOC is coming from 780. If USB is louder than LSB, the IBOC is coming
from 760.

(note opposite direction from what you'd expect.)

To check that (say) 780 is in fact IBOC, listen to 780 in LSB or USB.
If you hear a diesel rumble, IBOC is on.
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