Greetings. Today is analog television cutoff day in the U.S., and millions of viewers will be left with no television -- or degraded quality signals -- as a result, often through no direct fault of their own (economic circumstances, logistical issues, and so on). But we've discussed the gross mismanagement of the digital television (DTV) transition in the past, and that's water under the bridge. I have a copy here of NBC's L.A. O&O station KNBC "turning off" their analog programming -- I'll try post it when I have a chance (it didn't go entirely on cue ...)

But today, I want to warn you about one aspect of the DTV transition that has been little discussed but is of very significant importance.

Many (perhaps most) digital television and DTV converter boxes do not rescan for digital channel changes -- especially critical on today's transition day.

This means that when many stations alter their "internal" digital channels/frequencies (to which the familiar channel numbers you see are mapped) those channels (including any old or new digital "subchannels") may vanish from your TV set.

To make sure that you're getting all digital channels properly, it is usually necessary to manually order your TV or converter to "rescan" all channels. This is especially important to do today and tomorrow as many channels shift frequencies, and should continue to be done periodically to pick up changes on digital subchannels in particular. The exact procedure for rescanning will vary from unit to unit -- dig around in the "menu" features of your set or box if you don't have the appropriate documentation.

The DTV info programs that many stations are running on their analog channels for a period of time starting today should mention the rescanning issue, but it's an important aspect of the transition that is easy to miss, and a factor that can bring even more confusion to viewers in an already confusing situation.

So remember, if you seem to be missing digital channels that you should be receiving, rescan your TV or converter, and do so periodically (perhaps once every several weeks) from now on -- forever. Note that for televisions hooked up to cable or satellite, none of this is an issue.

Does this whole digital TV transition mess seem like it ended up being too complicated and expensive? Thank Congress -- this was basically all their idea.

--Lauren--