In article Jerry Stuckle writes:

OK, you mean absolute power. Yes, they can lower the ERP - but that
does not necessarily lower the power for the signal. Remember at 1MW
the power was spread over 4.25 Mhz (assuming video only, of course).
Digital requires much less bandwidth, so they don't need as much power
to get the same effective signal. However, digital still requires a
stronger signal than analog, in the bandwidth provided. You need quite
a bit of noise before it becomes visible in analog. Digital, a single
noise pulse can cause the loss of several bits of information. Because
of the compression involved, this is more than one or two pixels.

Actually, if you look with a spectrum analyzer, the digital signal has
the power spread much more uniformly over the 6 MHz than analog did.

Digital stations here run substantially less power than their analog
versions did, and deliver much better results. The power is spread across
the 6 MHz channel - the signal uses the whole thing. By contrast, analog
had uneven distribution of the power across its spectrum.

The digital system has levels of error correction in the signal - wiping
out a few bits is unlikely to affect the demodulated result. Wiping out
a big burst of them is more likely to cause a problem.

Alan
wa6azp