Extra channels- Olevia vs. Polaroid

[pualzennon]

I just bought an Olevia 37" 237T LCD tv, and after the initial scanning I saw a few channels that I have not seen before from my standard cable service (Time Warner). E.g. 85-3 and 120-12. They are local broadcast network channels like Fox & PBS etc. But they do look sharper than the regular 3 to 11 feed. And the display info show either 720p or 1080i. Could these be actually HD, even though I have not subscribed to HD, and is not using any cable box?
My 1-year old Polaroid FLM 3232 (32" LCD) cannot pick up any of these extra channels. What makes the difference? Looking at the specs, the only relevant difference is 1080i for the Olevia, an 720p for the Polaroid.
What part of the spec would tell me a TV can pick up those extra channels?

[jagabo]

Cable companies in the USA are required to carry the local broadcast HD stations in unecrypted QAM. Yes, you are seeing HD broadcasts. Your other HDTV probably doesn't have a QAM tuner -- different than the ATSC tuner used for over-the-air HD which has been required on TV's for a while now.

[edDV]

Your local digital ATSC broadcast stations can transmit one program or several subchannels. These can be 704x480 SD or HD. Most major network stations are transmitting their primary channel in 720p or 1080i with SD programs upscaled. 4:3 aspect programs will have side bars. Some stations have secondary channels showing news or weather. PBS stations usually have multiple subchannels.

The cable companies receive these programs from the broadcasters and remodulate them as digital cable channels with QAM modulation. These are normally not encrypted and are available with even basic cable service. All that you need is a digital TV or VCR with a QAM tuner. If the TV is a HDTV, these channels will be received in high definition.

Some digital TV sets with QAM tuner directly tune the cable channel numbers like yours. In that case the numbers will look like n.m where n is the actual cable channel and m is the MPeg2 multiplex subchannel (e.g. 86.7 or 112.3). Cable companies often offer a virtual ID that some digital QAM tuners display instead of the raw number. This might look like "4-1" or "KXYZ-DT1" or "KXYZ-HD" or some variation. Many cable systems offer the additional subchannels as well like "KXYZ-DT2".

Bottom line, if you are on cable and want a new TV, make sure it has a QAM tuner. Otherwise a cable box is required to get these digital stations. Analog versions of the primary channel will also be made available in NTSC but the quality will be less.


PS: Digital TV sets with QAM tuners will do three scans.

The first scan will be for the analog NTSC tuner. Analog broadcast channels will be disappearing over the air on Feb17,2009 but will remain available on cable until at least 2012. Additional two digit analog cable channels will be found.

The second scan is for ATSC over the air digital broadcast channels. For a cable connection, none will be found.

The third scan is for QAM digital cable channels. At a minimum you will get the local digital broadcast stations. Some cable systems offer additional channels without encryption. TV sets that have "cablecard" and a subscription can receive encrypted QAM channels according to the subscription plan. All this without a cable box.

[pualzennon]

Thanks for the helpful info. Would DVD recorders have this QAM tuner available also? My Panasonic DMR-ES15 doesn't seem to have. If I buy a new recorder with a QAM tuner and record HD programs, would the quality be better than SD, even though it is only a NON-HD recorder?

[edDV]

Thanks for the helpful info. Would DVD recorders have this QAM tuner available also? My Panasonic DMR-ES15 doesn't seem to have. If I buy a new recorder with a QAM tuner and record HD programs, would the quality be better than SD, even though it is only a NON-HD recorder?

Some DVD recorders have QAM as well as ATSC tuners. Like a SD digital TV, DVD recorders downscale 720p or 1080i channels to letterbox* 704x480i for recording. Pass through to output is also 704x480i.

Some DVD recorders allow anamorphic (full height horizontally squeezed) 480i recording for 16:9 source. This is a highly desirable feature. An LG recorder I tested a few months ago had this feature.

You should get better quality recording from the QAM digital channel vs. the analog NTSC channel.