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Old 04-15-2017, 01:12 AM
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old_tv_nut old_tv_nut is offline
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Join Date: Jul 2004
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There was a long, tortuous path to the VHF DTV problem, mainly due to the fact that the original coverage equations used by the FCC did not take into account the actual full amount of ambient noise in the spectrum at VHF, which apparently has only increased over the years. As a result, some stations chose VHF where they could because of the predicted wide coverage and the much lower transmitter power bill - the VHF signal does refract further over the horizon than UHF. So, signal levels at VHF are as predicted, but noise levels are higher than predicted. The solution would be for all VHF stations to increase power simultaneously, thereby overcoming atmospheric noise and keeping the co-channel ratios constant - BUT, since many of the stations were built to the predicted required power, such a simultaneous increase is just not practical. Hopefully this will be rectified with ATSC 3.0, both by coding gains and power increases; but with the need to co-exist with ATSC 1.0 for a time, the power increase may need to be phased in.
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