# HDTV and QAM Tuning **URL:** \ **Category:** Factual Questions\ **Created:** [April 3, 2008, 7:31pm UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836 "2008-04-03T19:31:05Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Merijeek](https://avatars.discourse-cdn.com/v4/letter/m/f05b48/32.png) [@Merijeek](https://boards.straightdope.com/u/Merijeek)\ **Post date:** [April 3, 2008, 7:31pm UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836/1 "2008-04-03T19:31:05Z")
Hi all. I recently got myself a Toshiba Regza 47" 1080P LCD TV. Connecting up to Comcast, I get about 400 channels, a good chunk of which are, of course, music channels. Thing is, part of the auto-scan comes up with a bunch of channels located at 0. Is this typical? Strangely enough, I don’t get a CBS-HD feed, even though internet listings say I should be getting one at 13-1. Is all of this typical? Do I maybe have a bad tuner, or is this weirdness normal? -Joe ---
**Author:** ![3waygeek](https://avatars.discourse-cdn.com/v4/letter/3/e95f7d/32.png) [@3waygeek](https://boards.straightdope.com/u/3waygeek)\ **Post date:** [April 3, 2008, 7:45pm UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836/2 "2008-04-03T19:45:46Z")
13-1 is probably a broadcast channel number – if you were hooked up to an antenna, you’d get it. Also, the must-carry rule doesn’t seem to apply to HD channels; cable operators are apparently not required to carry the HD feed of local stations. I’m on Charter in metro Atlanta, and there are a couple of local stations whose HD feeds we don’t get, for reasons unknown to me. ---
**Author:** ![Merijeek](https://avatars.discourse-cdn.com/v4/letter/m/f05b48/32.png) [@Merijeek](https://boards.straightdope.com/u/Merijeek)\ **Post date:** [April 3, 2008, 7:47pm UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836/3 "2008-04-03T19:47:22Z")
[QUOTE=3waygeek] 13-1 is probably a broadcast channel number – if you were hooked up to an antenna, you’d get it. Also, the must-carry rule doesn’t seem to apply to HD channels; cable operators are apparently not required to carry the HD feed of local stations. I’m on Charter in metro Atlanta, and there are a couple of local stations whose HD feeds we don’t get, for reasons unknown to me. [/QUOTE] Well, thing is I get all the major channels in HD except for CBS. FoxHD comes in at the expected 40-1, etc. Just CBS doesn’t get found, for some reason. And the 0 channels are weird to me. -Joe ---
**Author:** ![Flander](https://avatars.discourse-cdn.com/v4/letter/f/8c91f0/32.png) [@Flander](https://boards.straightdope.com/u/Flander)\ **Post date:** [April 3, 2008, 7:52pm UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836/4 "2008-04-03T19:52:23Z")
Reported your duplicate OP. Otherwise, I’ve got nothing to add. ---
**Author:** ![Iggins](https://avatars.discourse-cdn.com/v4/letter/i/b9e5f3/32.png) [@Iggins](https://boards.straightdope.com/u/Iggins)\ **Post date:** [April 3, 2008, 8:03pm UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836/5 "2008-04-03T20:03:54Z")
Is this the Toshiba 46XF550? I bought one myself, but I didn’t try the QAM. I just tried ATSC, and I use FIOS TV and TiVo. Nothing helpful to add, except that I’m surprised that Comcast has that many QAM channels. ---
**Author:** ![Iggins](https://avatars.discourse-cdn.com/v4/letter/i/b9e5f3/32.png) [@Iggins](https://boards.straightdope.com/u/Iggins)\ **Post date:** [April 3, 2008, 8:16pm UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836/6 "2008-04-03T20:16:26Z")
A quick Google search turns up some instances of various channels not mapping properly to the correct QAM channel. Some at 13-1, some at others, and with various stations (ABC, CBS, etc.). I also saw a few references to several digital channels getting mapped to “0” at the same time. Maybe it’s related to how your decoder interprets the QAM information from Comcast. Again, not too helpful, but more information… ---
**Author:** ![3waygeek](https://avatars.discourse-cdn.com/v4/letter/3/e95f7d/32.png) [@3waygeek](https://boards.straightdope.com/u/3waygeek)\ **Post date:** [April 3, 2008, 8:26pm UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836/7 "2008-04-03T20:26:22Z")
Cable operators use QAM for most of their digital channels (i.e. everything past channel 99); most of these channels will be encrypted, so a non-cableCard tuner won’t pick them up. FCC rules require operators to use clear QAM for local HD channels (but allow an out for “significant levels of cable theft”, IIRC). My operator, Charter, has 3 or 4 digital cable channels (MTV/U and a couple others I can’t recall) that come in on clear QAM, but aren’t available through the cable box. Many operators place pay-per-view or OnDemand content on otherwise unused channels, using clear QAM, then send a command to the customer’s cable box mapping that QAM channel to a specific cable box channel. When I first set up my QAM tuner, I picked up a couple of pornos some of my neighbors had ordered :eek:. Re-tuning those channels a bit later, I got nothing. Note that it is not entirely legal to piggyback on others’ purchases this way, so don’t do it. I only mention it so you won’t be surprised if some channels you get during your set-up phase stop coming in later. ---
**Author:** ![Merijeek](https://avatars.discourse-cdn.com/v4/letter/m/f05b48/32.png) [@Merijeek](https://boards.straightdope.com/u/Merijeek)\ **Post date:** [April 3, 2008, 8:28pm UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836/8 "2008-04-03T20:28:38Z")
Of course, before I start saying something too stupid I need to see if I meant QAM or ATSC… (googles) Good. Yes, QAM=cable, ATSC=OTA. So, yes, that’s what I’m getting QAM. **Iggins** , did you find anything helpful on the stuff you dug or, or just people reporting it happening? -Joe ---
**Author:** ![Iggins](https://avatars.discourse-cdn.com/v4/letter/i/b9e5f3/32.png) [@Iggins](https://boards.straightdope.com/u/Iggins)\ **Post date:** [April 3, 2008, 10:49pm UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836/9 "2008-04-03T22:49:23Z")
[QUOTE=Merijeek] **Iggins** , did you find anything helpful on the stuff you dug or, or just people reporting it happening? -Joe [/QUOTE] Unfortunately just reports of problems. It seems that the problems eventually get fixed, just unpredictably. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [April 4, 2008, 12:08am UTC](https://boards.straightdope.com/t/hdtv-and-qam-tuning/443836/10 "2008-04-04T00:08:04Z")
[QUOTE=3waygeek] 13-1 is probably a broadcast channel number – if you were hooked up to an antenna, you’d get it. Also, the must-carry rule doesn’t seem to apply to HD channels; cable operators are apparently not required to carry the HD feed of local stations. I’m on Charter in metro Atlanta, and there are a couple of local stations whose HD feeds we don’t get, for reasons unknown to me. [/QUOTE] The reason is the local channel wants the cable carrier to pay for the HD broadcast. This is becoming a real sh\*t storm in some areas. There are some broadcasters who interpret that the Standard Definition signal is the “over the air” signal that falls under the must-carry rule, and that the HD channel, as well as any secondary channels are extras. Not surprisingly, the cable companies take the position that since the HD channels are broadcast over the air, the cable company should be able retransmit it without having to pay. Something tells me the FCC didn’t anticipate this when they came up with the digital TV regulations.