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Old 10-31-2017, 11:06 PM
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old_tv_nut old_tv_nut is offline
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Join Date: Jul 2004
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This issue has come up on video karma multiple times, and I will now give the same answers I have before:

1) The FCC planning factors did not take into account the level of environmental noise present in the VHF bands
2) at low VHF antennas are less efficient than they could be due to size limitations
2a) at low VHF antennas are less directional and more susceptible to ghosts
2c) the ATSC 1.0 system depends on the capability of the receiver equalizer to handle ghosts, especially moving ones. ATSC 3.0, like DVB, will have a specific ghost immunity (guard band) depending on the particular choice of coding parameters for a subchannel; the broadcaster will determine at what delay range / level of ghosting the viewer will lose signal
3) During the transition from analog, the power could not be boosted due to interference with analog co-channel stations. Power could be boosted now, but in order for the more tightly packed digital co-channels not to interfere with each other, they would all have to boost simultaneously. Practically impossible both technically and economically.
4) Near the Canadian and Mexican borders (read, the complete tiers of northern and southern states), power cannot be changed without international agreement.
5) Because of antenna size problems, cell phones must use UHF. The cell phone providers have much more money and clout than the broadcasters these days, (there are many more cell phone customers producing much more revenue than the advertising that supports OTA TV customers, plus many people today are completely unaware that you can get OTA, but they all want mobile phones) so the spectrum negotiations go in favor of mobile.
6) Maybe ATSC 3 allocations and repacking will be a chance to raise VHF power, and maybe broadcasters will use more robust, more highly coded, (but lower bit rates) for at least some of their services; or some combination of the above. It remains to be seen.
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