The old method of transmission of TV broadcast over the air is being stopped on June 12.  Older TVs will not be able to receive any signal at all without a digital to analog converter.

If you have cable or a satellite dish or a newer TV, the unit has a digital to analog converter built in.  Otherwise, you need to get a converter or a new TV.

Its that simple.  But ...  (There's always a but.)

During the planning stages of the switch, it was realized the channels the stations were assigned to were already occupied by their own analog channel.  So a scheme was incorporated into the standard for a station to broadcast on a new channel, but still be referred to by their old number, so people wouldn't get confused.  But now, on June 12, their old channel will become unoccupied and the stations will switch the digital channel back to their old channel.

Because of this, when June 12 arrives, stations will stop transmitting on their analog channel and move their digital channels to that channel.  This will require TVs and converters to rescan the channels and figure out who's broadcasting where.  The information is all there, in their signals, but the TV has to check them all and switch things around.

Why are they doing this?

The old channels were terribly inefficient, both in terms of space, and in terms of power usage.  Far less space is now required for many more channels. This frees up some prime "real-estate" on the dial. This space, channels 52 to 69, will be auctioned off by the feds. Some have already been auctioned, for some 20 billion dollars, for new services. Channels 54, 55 and 59 were sold and in some areas are already being used for broadcasting and Internet access. For example Qualcomm in 2007 started using Channel 55 for broadcasting TV to cell phones in New York City, San Diego and elsewhere. Watch for other new wireless systems to be rolled out after the June 12 deadline.

What do I care?

In the past, one of the primary reasons people subscribed to cable TV or satellite service was to get a nice clear picture.  If you're one of them, you can save a big sum of money now, because digital transmissions are always nice and clear, if you have good reception.

Here in the Spring Hill / Brooksville area, we are on the fringes of the broadcast area, but good digital reception is possible.  For a couple hundred dollars, you can have a good outdoor antenna installed, or you may already have one.  It will allow you to receive a large number of channels.  I have a 30-year-old outdoor antenna that was here when I moved in.  TV reception was not good, because I had been used to cable or satellite.  But, since we had been traveling in an RV for several years, we had only a portable TV.

We bought a new digital TV, the cheapest one I could find, and hooked it up to the old antenna.  Voila!  29 channels, all crystal clear with no "snow" or other interference.  Some of them are in Spanish, or are otherwise of no interest, but still, we get around 20 distinct channels, including 2 weather channels, an oldies channel, a movie channel, a news channel, and all the regular networks.

There is also a program guide, produced by the newer TVs or by the converter box from information contained in the new signals and provided by the stations.  It tells what's on now and what is scheduled for each station that provides the information.

Alas, there's no ESPN.  But how much can a few sporting events a month be worth?  Not that much, to me.

How about HDTV?

HDTV is digital TV, only more so.  Most sets sold today are HDTVs, and most network programming is HDTV.  Old reruns and movies are not. There's a lot to know about HDTV.  The new broadcast standard, which replaces the old one on June 12, allows for one "high definition" channel to occupy the space formerly used by one old-style channel.  It also allows for up to 4 "standard definition" channels to occupy that space on the dial.  So many broadcasters are choosing to broadcast more than one channel where they used to have only one.

In additon to the picture quality, HDTV can also accomodate full surround sound, like at a movie theater, or with a DVD player and sound system.

The shape of the picture is variable.  HDTV's are now all 16 units of measure wide and 9 units of measure high, called 16x9.  It looks more like a rectangle than the former standard, which was more square at 4 units wide and 3 units high, called 4x3.  A broadcaster can choose to show a program in either of these two shapes, called "aspect ratio."

In order to handle the foreseeable future, the new standard allows for even higher definition.  Nobody is broadcasting in this higher definition, but "Blu-Ray" DVD players can produce signals at this higher definition.  For very large TVs, greater than about 40" perhaps, the difference is noticeable, but not otherwise: your eyes cannot see well enough!

Summary

There are several digital "content delivery" vehicles: broadcast, cable, satellite, DVD, and Blu-Ray DVD.  They all differ in their nitty-gritty details, but they all deliver far superior picture and sound.

Cable is probably the lowest definition, since cable providers (except fiber optic ones, like Verizon FIOS), must "compress" the signal in order to get more channels down the wire.  They have been doing this for many years, since the advent of "digital cable."  Their advertising always says "digital quality" picture and sound.  This is meaningless, since digital can be of any quality they choose.  Notice they don't say "highest" quality.

Satellite is in a similar boat.  They have a limited amount of "space" in their transmissions, and they must compress the signals to get more of them.

Broadcast can, but often does not, deliver the highest quality for normal sized TVs.  Its better than DVDs.

DVDs can, but sometimes do not, deliver the next highest quality for normal sized TVs.

Blu-Ray can, and usually does, deliver the highest quality for any sized TVs.

I happen to know quite a bit about this kind of thing.  So if you have any questions, I can either answer them of my own knowledge, or find out for you.  Ask away, below: