What criteria does the the Loss-of-Signal circuitry use when determining presence of a valid SDI signal?
The LOS register section states:
"The LOS register reports an open inputs fault condition for each of the inputs. The following table shows the register mapping... Reading a [0] from the bit D[0] indicates an open inputs fault condition on the IN0. A [1] indicates presence of a valid signal" (pg.17).
Since the inputs are AC-coupled, it can't be looking for a simple open circuit, and the "presence of a valid signal" seems to indicate something more sophisticated than a merely detecting voltage at the input.
Any further information or clarification on this point would be appreciated.