There are two types of digital tuners:
- ATSC tuners allow reception of local digital television channels transmitted “over the air” by local broadcast stations in North America.
- QAM tuners allow reception of digital cable channels encoded and transmitted via cable television providers.
The Federal Communications Commission (FTC) requires that all televisions sold in the United States be able to receive "over the air" signals transmitted by local broadcasters (i.e. have at least an ATSC tuner) but does NOT require manufacturers to include QAM tuners.
While normally manufacturers will include both ATSC and QAM tuners, the highly competitive market of LCD/LED TV’s leads manufacturers to cut costs by limiting the number and types of inputs/outputs. Some manufacturers do not equip some (or any) of their models with QAM tuners in order to offer their product at a reduced cost.
NOTE: TVs with just an ATSC tuner will not receive digital cable channels.
The bottom line? Check the specifications carefully before purchasing a TV and make sure the model includes a QAM tuner.