Originally Posted by hdtvluvr
So what channels do you lose using the DTA vs directly wired for QAM? In other words, QAM has SD channels and HD equivalents of the locals. Do you still get the locals in HD using QAM? Do you get the non local HD channels using QAM? What actually changes and why would one need to use an X-Y switch?
You get all the locals including sub channels EXCEPT they are in "SD" -- analog, actually, because the digital is translated to analog channel 3 to feed your TV. Some channels will appear 4.3 pillarboxed. Some will appear 16:9 within 4:3 (black bands all four sides). Essentially, the DTA is a QAM tuner and decrypter. The problem is that the digital channel is then converted into analog (channel 3/4) and fed to your TV as if your TV was analog.
Supposedly, Channels 2-19 are going to remain unencrypted so you can still tune them with your QAM HDTV (no DTA). But I've read that the cable companies want permission to encrypt those channels, too. Once that happens, you will no longer be able to get anything with a bare TV. The cable company will then be able to charge you a fee for each TV in the house.
In th meantime, here is what I'm going to do with one of the TVs. I have a recent vintage VCR with an analog tuner and with component and HDMI outputs, but you could still do this with older model with composite outputs. I'm going to split the Comcast cable, feed one wire directly to RF on my HDTV. The other wire will go to the DTA which will feed the VCR, which will then feed the HDMI or whatever input on my HDTV. Thus, to watch all the expanded basic channels I'll watch the HDMI input, via the VCR+DTA. If I want full HD, I'll switch to the the RF input and tune QAM.
Boiling it down: The reason for this split cable + VCR nonsense is that DTAs only have RF-out and HDTVs generally have only ONE RF input, and if the DTA occupies that input (and blocks the digital streams), you are sunk. The VCR is used as a device to translate the DTA's RF output to something else your TV can accept - HDMI, Composite - so that you can still plug the cable into the TV's RF input and tune QAM.
1. Broadcast channels (2-13) come through in 4:3. Cable channels like CNN - if they are available in HD - come through as 16:9 panels within the 4:3 frame.
2. I don't know for certain whether QAM will still work after they complete the digital changeover - shutting off the analog signals and doing whatever reorg with the digital streams. Comcast literature seems to say that channels 2-20 (what is termed, "limited basic") will still be available via open QAM. So that's what I'm assuming. But the industry trend is to go even further: Encrypt everything.