Originally Posted by speedlaw
I have Cablevision. They pass HD signals as 2.1, 4.1, etc. They pass local channels too, (public access) but with intentionally bizarre numbers (99.124, 99.185). They come in clear QAM, only the OTA channels. So, even though analog is gone, and the Cable Co is using this to make sure you now have to rent a box for $8 per month forever per set, you will probably still get clear QAM for the OTA channels. Everything else is scrambled. If you get the HD with Cablecard, you get 702, 704, etc, but if you hook up the QAM tuner, you get them as 2.1, 4.1, etc. We cut all CATV service, keeping phone and internet....but we still get the OTA channels in clear QAM. I think the FCC requires this in most markets, save NYC and a few other cities.....sorry.
My TiVo won't work on the "free" QAM channels, because it can't match the guide and the 2.1 or 4.1, and you can't trick the guide into using the OTA guide.....whereas the Sony will do this.
Short answer, most folks will still get clear OTA via QAM even if they shut off cable, provided they still have some service to the home. I cut the cord last week, but with OTA (which is good for my sony boxes and the Tivos) and Hulu plus for the three cable shows I actually watched.
QAM is used for cable. OTA broadcast digital uses 8VSB modulation. the two are the same frequency from 2 - 13.
My Tivo Premiere Series 4 will perform manual recordings of clear QAM but the guide needs a cable card.
The 2.1 or 4.1 are probably PSIP virtual channels like your 700 and 704. Note that the 700 is a display issue and the clear QAM frequency is the physical location. You can verify a station's frequency with Wiki by using its call letters also. Sometimes they are the same.