Friday, January 8, 2010

Comcast's new DTA box and standard QAM channels

When during the time of last year's government mandated switch to digital broadcasting Comcast assured its customers that there is nothing to worry about as long as you have cable -- well, that was not entirely truthful. Just a few months later Comcast customers were forced to aquire inconvenient digital to analog boxes. As of now, in most locations you can no longer watch "high channels" without such a box or some other kind of Comcast receiver. The absolute worst thing is that most of these DTA boxes have a single coaxial output. This means that high-def channels transmitted without encryption can no longer be watched, unless you do something creative. It has been very unfortunate for Comcast not to be able to scramble those channels to begin with, because legally they cannot do it. These channels are available off-the-air and as a result they must be available to Comcast customers with basic cable service at no charge. The channels are still available, but Comcast found a way to make watching them as inconvenient as possible. The hope is, of course, that people will want to subscribe to Comcast's high-def service. If you don't want to do that there are several things you can do.

First of all, you probably will have to split the cable signal. Then you can send one line directly into the QAM-enabled TV and the other line will go into the DTA box. (Instead of a splitter you can use an A-B switch. There are even some that come with a remote, but you will have to spend over $40 on that.) From the DTA box you can send the converted signal to some tuner device. An old VCR would work just fine, if it has a tuner. Then use RCA cables (yellow, white and blue) to connect the VCR to the television. Set the VCR to channel 3 (or 4 in needed). Now you will have QAM channels trough the TV's digital tuner and all the high analog channels can be easily accessed on the AV input (controlled by the DTA remote).

Update

Turns out (unsurprisingly) that Comcast uses standard QAM channels to transmit digital signals. It means that all the "higher" channels are still available on any TV that can receive QAM. They are assigned to various channels in the 70-90 range. All the DTA does is simply modulating the signal into analog form and assigning the same channel numbers as before. The only problem that I seem to notice is that the audio is not in sync on some channels. The DTA must be doing something to rectify this, but many channels look just fine and the sync problem is negligible. In fact, syncing problems are commonplace with QAM, in my experience. So, just run a channel scan on your digital TV and see if you are satisfied with the results. If you only have an analog tuner then the box is actually a good thing, because you will be getting better quality picture.

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