What is "Clear QAM" - AVS Forum
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post #1 of 13 Old 12-16-2008, 04:30 PM - Thread Starter
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Hi all,

I've had directv forever but I'm trying to help someone with cable TV. I have some questions, this is the first one.

Thanks

Bob
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post #2 of 13 Old 12-16-2008, 04:34 PM
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Read this and let us know if you have any questions:

http://en.wikipedia.org/wiki/QAM_tuner

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post #3 of 13 Old 12-16-2008, 04:38 PM - Thread Starter
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Is the opposite of "Clear QAM" encrypted QAM?

Bob
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post #4 of 13 Old 12-16-2008, 04:53 PM
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Quote:
Originally Posted by rbmcgee View Post

Is the opposite of "Clear QAM" encrypted QAM?

Correct. To get the encrypted stuff you need:

1. A cable box from the cable company; or
2. A TV with cableCARD; or
3. A DVR with cableCARD; or
4. A pre-built HTPC with cableCARD.

There was talk of allowing consumers to buy their own cable box and put a cableCARD in it, but I don't know if this has happened.

See here for more info:

http://en.wikipedia.org/wiki/CableCARD

Typically the cable companies broadcast the main networks (ABC, NBC, FOX, etc.) in the clear.

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post #5 of 13 Old 12-16-2008, 04:58 PM - Thread Starter
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My friend can hook a digital TV to the raw cable outlet (gets Charter Digital) with no cable box in the mix and receive channels. Does that mean that all those channels that can be tuned are clear QAM?

Bob
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post #6 of 13 Old 12-16-2008, 05:00 PM
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Quote:
Originally Posted by rbmcgee View Post

Is the opposite of "Clear QAM" encrypted QAM?

Yes - Clear QAM broadcasts are unencrypted.
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post #7 of 13 Old 12-16-2008, 05:04 PM
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Quote:
Originally Posted by sneals2000 View Post

Yes - Clear QAM broadcasts are unencrypted.

That's not necessarily true. Your friend could be looking analog content. How to tell the difference?

Digital channels have a decimal: 5.1 instead of 5
Digital looks better.

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post #8 of 13 Old 12-16-2008, 05:14 PM - Thread Starter
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This is where I get confused. The relevants:

Subscribes to Charter Digital cable

Hooks up a digital tuner TV to the raw cable and receives channels, tuned by the TV. No channels are .1 channels however many, many of them are "cable" channels (ESPN, etc).

Looks like analog to me.

Question, if they are analog, will those channels go away after 2/09? Or, do cable companies grab the digital signals, convert them to analog and then still pump it to your house? The cable company claims no problem getting the signals after the conversion date. Seems odd to me.

Bob
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post #9 of 13 Old 12-16-2008, 05:30 PM
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Quote:
Originally Posted by rbmcgee View Post

Question, if they are analog, will those channels go away after 2/09? Or, do cable companies grab the digital signals, convert them to analog and then still pump it to your house? The cable company claims no problem getting the signals after the conversion date. Seems odd to me.

It is only analogue OTA channels that are legislated to disappear in the US after 2/09.

Analogue cable channels can continue as apart from rebroadcasts of OTA channels (which if sourced from analogue currently will need to switch to a digital received version if to continue), almost everything else on analogue cable (including pay-TV stuff like ESPN) is distributed to the cable companies via a digital distribution system (off-air satellite or fibre AIUI)

However the OP was asking about QAM - which is the digital modulation system used for digital cable - with clear QAM being unencrypted, and pay-TV cable using encryptio. Analogue cable uses NTSC-M modulation AIUI.
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post #10 of 13 Old 12-16-2008, 05:32 PM
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Quote:
Originally Posted by chris5977 View Post

That's not necessarily true. Your friend could be looking analog content. How to tell the difference?

Digital channels have a decimal: 5.1 instead of 5
Digital looks better.

??? Analogue broadcasts use NTSC not QAM. The OP was asking about Clear QAM (which is a digital standard) not NTSC (which is analogue)?
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post #11 of 13 Old 12-16-2008, 05:32 PM
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Quote:
Originally Posted by sneals2000 View Post

Yes - Clear QAM broadcasts are unencrypted.

Quote:
Originally Posted by chris5977 View Post

That's not necessarily true.

sneals2000 is correct. All clear QAM broadcasts are unencrypted. If they are encrypted, then they are not "clear".
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post #12 of 13 Old 01-13-2009, 07:50 PM
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This is Clear QAM. Then Charter is clear QAM, at least in central MN. My parents recently bought a 32' HDTV and a 23' HDTV/Monitor and when I auto programmed the channels, the extended basic cable included these channels.
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post #13 of 13 Old 01-13-2009, 08:23 PM
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Quote:
Originally Posted by ryoushi View Post

This is Clear QAM. Then Charter is clear QAM, at least in central MN. My parents recently bought a 32' HDTV and a 23' HDTV/Monitor and when I auto programmed the channels, the extended basic cable included these channels.

A cable company can have both clear and encrypted channels on their system. "Clear" QAM is a per digital channel designation. It is possible to have 5.1 in clear QAM (unencrypted) and have 5.2 encrypted (not clear).

Channel 5 would be analog but the 5.1, 5.2, etc would be QAM. If your TV can pick them up without a cable box, then they are Clear QAM. Also, channel 5.1 could actually be on the frequency for physical channel 71. The reason this is possible is due in part to the Digital Transition. Broadcasters needed to keep transmitting their analog and you couldn't have a digital and analog channel on the same frequency. So your analog channel 5 could be broadcast on physical channel 17. They used the digital virtual channel to reassign the number that everyone would recognize (5.1).
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