HDTV Tuner and Cable
May 21, 2005 3:12 PM   Subscribe

Do standard “QAM” HDTV tuners work over conventional cable?

I recently purchased a front projector (Infocus 4805) for watching DVDs in the living room. As a consequence, I have moved the old tube TV out to storage. The problem is, the projector doesn’t have a TV tuner. When looking around at the price of standard TV tuners I found that it is just as cheap to purchase a HDTV tuner, which supposedly also have the ability to decode standard television signals. I also read that they include “QAM” reception, which is supposed to allow the reception of unscrambled HDTV over basic cable without any additional cable boxes or payments to the cable company. In fact Has anyone done this and does it work? I’d like to take a look at HDTV just for kicks, and this looks like a cheap way to do it.
posted by phatboy to Technology (6 answers total)
IIRC, it is possible for your cable company to send QAM over cable, but that's the catch--they have to intentionally do it, and I believe most use a different scheme.

Have you looked into setting up a regular antenna? Depending on your location, you might even be able to get away with rabbit ears on top of your receiver. Even if you can't, getting an antenna installed isn't that hard, particularly if you pay someone to do it.

Use antennaweb to help figure out which category you fall into. You're looking for the "-DT" channels.

Oh, and generally one would use a cheap VCR as a TV tuner--have HDTV receivers really dropped that far?
posted by trevyn at 7:16 PM on May 21, 2005

Response by poster: HDTV tuners seem to run about 100$ on ebay, which is comparible to what you see for a standard tuner. I actually have a cheapo VCR hooked up now, but the picture quality is pretty bad.

Unfortunately I get absolutly no reception OTA. My only hope for TV is cable.
posted by phatboy at 7:49 PM on May 21, 2005

Best answer: Your cable company almost certainly does use QAM for their digital channels (not the lower-numbered analog tier). There are several levels of QAM, like 16QAM, 64QAM and 256QAM. It's like the old days of dialup modems when they got faster and fast, going from 9600 to 14400 to 28800 to higher speeds.

Further, the de facto standard for HD transmission on digital cable in the US is now 256QAM, which allows for two HD programs in one 6 MHz slot (38.8 Mbps). So that tuner you get better be able to do 256QAM.

However, the key is "unencrypted". I'd expect that most cable companies encrypt (CA protect) all of their channels, and selectively authorize all receivers downstream to receive it. I dunno, though, maybe they do transmit those in the clear. Note: I'm talking about the digital channels; analog is completely different and yes often in the clear.
posted by intermod at 10:03 PM on May 21, 2005

Actually, that's a good point--why can't you just get an HD receiver and service direct from your cable company? Prohibitively expensive?
posted by trevyn at 2:16 AM on May 22, 2005

Best answer: You may be able to find some more anecdotal reports from customers of your actual cable company on http://www.avsforum.com/ (closed for a site upgrade as of this writing, should be back by afternoon). None of the major cable companies have made it a standard to broadcast using 256QAM "in the clear", but there are a decent number of local operators of those national chains that do. If you already cable, plug it into the ANT input of your HD Tuner (I have the HDTV Wonder from ATI and love it), and run a channel scan.
posted by Merdryn at 5:17 AM on May 22, 2005

Response by poster: trevyn:

Digital cable is something like 50$ a month, which I can't justify. We have the bare minimum service (10$/month) that the cable companies are forced to provide by the state government.

I more interested in the what I can get for free. I'm not actually that interested in watching the TV, I'm more interested in the technology.

I'll try looking for a cheap 256 QAM tuner.
posted by phatboy at 11:25 AM on May 22, 2005

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