question about non-digital cable channels

question about non-digital cable channels
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lhughes @ 30th Oct 08:11PM:
question about non-digital cable channels

OK this is probably a pretty basic/newbish question...

I have Comcast limited cable TV (in Seattle, WA). I don't have any kind of cable box. I don't have digital cable. I have a several-year-old cable-ready VCR that seems to tune in the channels I expect with limited cable and gives me a tolerable but not great picture.

I recently built my first HTPC and connected it to my home theater receiver. I installed an ATI 650 TV capture card in it, put a splitter on the cable line, and plugged the cable into the card/PC. I ran the software to scan for channels, and it found 35 channels. OK fine, but here begins my confusion...

The channels my ATI card found don't match up with the channels I can tune on my VCR. First of all, the VCR is old, so it only understands channels 5,6,7... and not anything like channel 5.1 or 5.2 which the capture card found. I don't get what that means, but it's generally been fine - I can usually find what I want to watch pretty easily - but I've just run into a snag: there's a channel (channel 21, called "The Seattle Channel") which my VCR tunes in just fine, but my ATI card & HTPC can't see. There's a show coming up on channel 21 that I wanted to record on my HTPC (and not on my VCR).

Aside from the problem of this particular show, I clearly just don't understand what is happening with my cable service and my HTPC, so I'm hoping someone here can help to lift some of my ignorance (thus dragging me out of the 1990's).
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Curlee @ 30th Oct 09:05PM:
Re: question about non-digital cable channels

I just checked, and here, The Seattle Channel comes in on channel 21 in analog (NTSC).

But channel 15 (was "KHCV", now "KPST") comes in as digital. As I recall, so does channel 20 (KTBW). So I suspect something similar may be happening with your channel 21.

I'm not familiar with the ATI-650, but its reporting channels as 5.1 etc. implies it has digital tuning capability. Are you running WinXP, Vista, or System 7?
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darcilicious @ 30th Oct 10:09PM:
Re: question about non-digital cable channels

You've got digital cable whether you realize it or not - that's what it means when your ATI HD 650 finds channels like 5.1, 5.2, etc. (You probably want to read up on the specs/capabilities of that capture card :) »ati.amd.com/products/tvwonder650/index.html )

Digital cable channels are in QAM format, while digital over-the-air (OTA) are in ATSC format.

As far as Channel 21 goes, it's probably still in analog but it's possible that your tuner will only do analog OR digital and not both (without rescanning for the other).

More generally, Comcast is in the process of dropping analog channels; eventually, there won't be any left, everything will be digital. In the process, many of the digital channels you're receiving now are not being encrypted, so your capture card is currently picking them up. HOWEVER, Comcast will be encrypted everything except your local channels so eventually that's all your capture card will be able to capture.

(More info: »Re: qam tuner)
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jasg @ 31st Oct 11:39AM:
Re: question about non-digital cable channels

To summarize, when you have 'limited cable' in Seattle (and other areas), you will find 4 types of unencrypted video being passed over the cable:

1. Analog SD (NTSC analog, standard definition) with analog channel numbers like 4,5,7... These are or soon will be limited to channels 2 to 29 and 71 to 99.

2. Digital SD (QAM signal, NTSC digitized standard definition) with QAM channel numbers like 80-2. Generally, these are what used to be Analog channels 30 to 70.

3. Digital HD (QAM signal, OTA high definition) with QAM channel numbers like 4-1, 5-1, 7-1. These are the ATSC broadcast channels from local stations.

4. Digital SD (QAM signal, OTA standard definition) with QAM channel numbers like 4-2, 5-2, 7-2. These are ATSC 'sub-channels' from local stations.

It is important to know that channels in group 2 above will eventually require a box from Comcast (a DTA) that converts them from Digital SD to Analog SD for use with old TVs.
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lhughes @ 3rd Nov 01:29AM:
Re: question about non-digital cable channels

thank you thank you thank you... very helpful replies.

So it turns out my tuner card can handle both digital and analog channels, I just had to attach a splitter and send the extra cable to the analog port/jack.

So now it detects several analog channels, including channel 21 which is the one I wanted to start all this, but unfortunately they all come in black and white. Pretty clearly this is an issue with my ATI TV Wonder card, since I can attach the same cable to my VCR and see the analog programming in color (yes, tried attaching the cable straight from the wall to the HTPC/card without a splitter).

I've posted this issue on the ATI & Visiontek forums but as I write this I haven't received any replies. I realize it's no longer a cable service question, but since you all have been so helpful I thought I'd keep ~~milking~~ asking questions here...

thanks again,
LH
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