Channel Usage
Channels T-7 through T-14 are sub-band channels and are not used for normal television channel distribution. These channels are used for sending video back to the cable television headend, such as by Public, educational, and government access (PEG) stations on a cable TV system. They are also used by cable modems for sending upstream data to the headend's CMTS.
Channel 1 frequency assignments, where provided, are non-standard. If a Channel 1 were inserted (A-8) between Channels 4 and 5, Channel 5 would need to move 2 MHz off-frequency, thereby pushing Channel 6 into spectrum needed for FM stereo radio by the same 2Mhz. Any assignment placing Channel 1 in its historical location before VHF Channel 2 would also be problematic, as the last cable reverse channel (T-14) now occupies frequencies from the defunct terrestrial Channel 1. Most systems that provide a (named) "Channel 1" will therefore either alias "1" to some higher converter channel (such as 101) or to a digital virtual channel.
Cable channels 2 through 13 operate on the same frequencies as broadcast television (the VHF band). They were assigned by the FCC. The other channels were assigned by cable television operators.
Cable channels 65 through 94 and 100 through 125 operate on approximately the same frequencies as broadcast television (the UHF band). Ultraband 65 and up will appear to be UHF TV 14 and up on most non-cable-ready analog television receivers; as each ultraband channel is exactly 2 MHz below a standard UHF TV channel, a slight fine-tuning of mechanical UHF tuners is all that is required to shift this block squarely onto the UHF dial.
Cable channels 57-60 fall over frequencies assigned for ham radio; this overlap is utilized for amateur television.
Cable channels 95 through 97 (90 - 108 MHz) operate on the same frequencies as FM radio, so cable companies offering FM radio will not show TV programming on these channels.
Cable channels 98 and 99 (A2 and A1, 108-120 MHz), if used, have appeared as channel 00 and 01 respectively on some converter boxes
Many cable providers currently don't distribute any video content above channel 139, or about 900 MHz. As of 2009, it is common for TVs in North America with built-in tuners to not search analog or digital channels above channel 139. Most TVs made before 2005 do not include a QAM tuner, and only have an analog cable tuner which often cannot tune beyond channel 125. With the addition of services such as premium HD content, cable providers such as Cox Communications and Insight Communications have begun to roll out digital cable services which use frequencies up to 1Ghz (analog channel 158), while also dropping the analog channel formats.
Read more about this topic: North American Cable Television Frequencies
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