DTv Transition

[vod2117]

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[bicker]

A bit of confusion came up in another thread that had to do with what do we actually get out of the digital television transition, beyond the obvious.

First, the obvious: The digital transition clears off a large block of channels (everything from 52 up). This bandwidth is therefore going to be available for other uses, most notably, better communications for emergency service workers. Also, a good bit of this bandwidth will be auctioned off to commercial wireless service providers so that they can provide new, advanced services. Also, the move from analog to digital will help put an end to snowy television reception: With digital, you either get a crystal clear picture, or no picture at all. Finally, more folks will be receiving viewable television reception with digital, after the transition, that is received with analog, before the transition (89% vs. 11%).

Second, the not so obvious:

One television channel uses up 6 MHz of bandwidth. It doesn't really matter what that means; what is important is that there is a certain amount of MHz (think of it as "space") available for television stations, and each one takes up 6 MHz. They take up that space for their local area, and for all surrounding areas, due to the potential for interference. (In some areas, interference can go pretty far, like from Chicago all the way to Dallas -- an unfortunate reflection of the laws of physics).

An analog television channel used up the entire 6 MHz. One channel. With digital, a channel can contain enough data to present to you a number of different channels. So on a channel that used to show a standard-definition (SD), sometimes a little snowy CBS affiliate, can now ride enough data to show a crystal clear, high-definition (HD) CBS affiliate, plus a couple of clear, SD side channels, like a 24 hour a day weather report, plus a 24 hour a day, SD old movies channel.

How many channels can ride on one channel depends on a lot of things, including how much the broadcaster is willing to trade-off resolution quality for more programming. Generally 1 HD channel + 2 SD channels can fit comfortably without any real noticeable degradation of any. 1 HD + 3 SD channels seems to be very common (with some very minor degradation of the SD channels typically apparent, but not necessarily any degradation of the HD channel). Cable service providers manage to get 2 HD channels on one channel with very little degradation, but I don't see any over-the-air broadcasters trying that.

This ability to have several channels riding on the same channel, with digital television, is why the channel numbers look different. Before, you'd turn on "Channel 4" for WBZ here in Boston -- now you tune in "Channel 4-1". That's because there might be sub-channels, riding along with the main WBZ channel, i.e., there might be a "Channel 4-2".

So bringing this back to the original point of this message: Around here, a few channels use the 1 HD channel + 3 SD channel arrangement. Typically, the main channel, i.e., the "#-1" channel, is the HD channel, with most of the best programming. The sub-channels ("#-2", "#-3", etc.) typically provide less popular programming.

In one case, here, the side channels are a kid's channel on #-2, a lifestyles-type channel on #-3, and a religious channel on #-4. (For those reading this message because they following the link I posed in the other thread, this is what I was talking about in that other thread... that program we were talking about was broadcast here in Boston, last night, on "Channel 68-4", the religious sub-channel of "Channel 68".)

 

[2x_dis_dad]

Thanks for the info. I have dish network so the changeover wont affect me. I just cant wait till all the commercials about it are gone.

 

[happygirl]

I really hate it. I have Direct TV. I can;t get local channels with them. So when the change over takes over I will lose my local channels

 

[Morganpics]

I have my converter box and antenna. BUT, if the weather is crappy, like tonight, forget it. Nothing comes in. We have Directv with local channels, but they are from an area of the state we don't want to watch from. I was really hoping with the box we would be able to keep the locals we prefer. Not really sure now.

 

[bicker]

My understanding is that all recent DirecTV tuners, that can get local analog broadcast channels, can tune in local digital broadcast channels as well.