QAM tuner

From Wikipedia, the free encyclopedia

A QAM tuner is present in some new digital televisions and similar devices. It enables direct reception of digital cable channels without the use of a set-top box. QAM stands for "quadrature amplitude modulation," the format by which digital cable channels are encoded and transmitted via cable. QAM tuners can be likened to the cable equivalent of an ATSC tuner which is required to receive over-the-air (OTA) digital channels broadcast by local television stations. Many new digital televisions contain both and are labeled "with ATSC/QAM Tuner". Unlike the case with ATSC tuners there is no FCC requirement that QAM tuners be included in new television sets. However, there is a loophole and a television can still be sold without any tuner, if it is labeled as a monitor and not advertised as a television.

An integrated QAM tuner allows the free reception of unscrambled digital programming sent "in the clear" by cable providers, usually local broadcast stations; however most digital channels are scrambled because the providers consider them to be extra-cost options and not part of the "basic cable" package. Which channels are scrambled varies greatly from location to location, and can change over time. In the United States a television that is labeled digital cable ready can have a CableCARD installed by the cable provider to unscramble the protected channels, allowing subscribers to tune all authorized digital 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.