Forum Archive Home -> Glossary -> QAM, QAM tuner
QAM, QAM tuner |
| Baldrick posted 2009 May 12 03:47 |
| In North American digital video, a QAM tuner is a device present in some digital televisions and similar devices which enables direct reception of digital cable channels without the use of a set-top box. QAM-based HD programming of local stations is sometimes available to analog cable subscribers, without paying the additional fees for a digital cable box. The availability of QAM HD programming is rarely described or publicized in cable company product literature. If cable providers provide rebroadcasts of locally aired programming, they must also carry rebroadcasts of high-definition digital locally aired programming, in an unencrypted form, that does not require the customer to use leased equipment, per FCC Sec. 76.630 and CFR Title 47, §76.901(a). These usually include the local affiliates for CBS, NBC, ABC, PBS, and FOX, and the cable providers comply by rebroadcasting them over QAM channels. The law does not require the cable provider to advertise their availability, and the cable customer service representatives are known to unequivocally (and incorrectly) insist to customers that a converter box is mandatory to view any HD channels.
wikipedia |
| jagabo posted 2009 May 12 06:55 |
| QAM can carry SD too. So you will likely get a mix of SD and HD programming.
Clear (unencrypted) QAM is usually limited to your local over-the-air broadcasts and a few other channels (maybe local access, weather, etc.). The rest of the digital cable channels will be encrypted QAM and not viewable without a set-top box. |
| filmboss80 posted 2009 May 12 09:14 |
| Yep. Comcast in the USA makes damn sure that every HD channel except the local ones are scrambled. You have to pay extra for the cable HD channels and use their box. I'm pretty sure it's also that way with Time-Warner.
I can get the QAM SD channels, but I'm not impressed. These cable systems tend to further compress the image. When it comes to high-motion sporting events, digital cable is inferior to the old analog broadcasts. |
| usually_quiet posted 2009 May 12 10:52 |
| The Wikipedia article doesn't provide complete information. There are exceptions to the must-carry rule requiring cable providers in the US to carry full-power digital broadcast stations, unencrypted, and in their original broadcast format and quality.
Commercial stations have the option to give up their must-carry status and enter into a retransmission consent agreement with a cable provider, which lasts three years, and determines how the staion's channels are carried. Also, if the cable provider is a small-time operation with limited resources, it can apply for a waiver from the FCC that allows it to carry only SD or analog versions of the must-carry channels instead of HD, or drop some of the subchannels entirely. If stations choose retransmission consent, they can demand payment, or ask for other considerations in exchange for carriage, but if the cable provider and the station can't reach an agreement, then the station is dropped from the channel line-up. If stations choose must-carry, the cable service does not give the station anything in exchange for carriage, but must provide the station's channels as described in the Wikipedia article. Many commercial stations choose retransmission consent over must-carry. Because of a retransmission consent agreement, my cable provider encrypts the HD subchannel for two out of the nine local broadcast stations they carry. To watch those, subscribers must pay for the HD package and rent converter boxes. Only the SD subchannel for those two stations is left unencrypted. |
| edDV posted 2009 May 12 11:10 |
| Also for "must carry" stations, only the primary channel is required to be carried in clearQAM. Subchannels don't have to be offered at all.
Exception is PBS where the cable industry as a whole has agreed to carry all PBS subchannels in clearQAM digital but only the primary channel needs to be carried in analog. |
| jagabo posted 2009 May 12 11:17 |
| And don't be surprised if your cable company shuffles the QAM channels around a lot. |
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