tested said:
Several years ago the FCC allowed KCEN in the Waco-Temple-Killeen market to run its digital signal on channel 9 which overlaps with WFAA's digital signal in the southern part of the DFW viewing area. (KFWD will get channel 9 when the transition is complete) I also notice that the FCC has allowed KSWO-DT in Lawton/Wichita Falls to operate on channel 11. It appears this signal will overlap with KTVT in the northwestern part of the DFW area when they move back to channel 11 after the transition.
Can someone explain why the FCC would allow such obvious technical nightmares to happen? I would assume there was some protest over this by both KTVT and WFAA. I'm just curious what reason the FCC gave to grant these applications.
In analog TV, the vast majority of VHF stations are using the maximum power for their channel (100kw chs. 2-6, 316kw chs. 7-13). And the FCC requires stations on the same channel be spaced some minimum distance regardless of the power used. KWAB-4 Big Spring has to be at least 190 miles from KDFW-4 Dallas, even though KWAB is only running 13 kilowatts at about 450 feet. Directional antennas can be used to avoid wasting power over unpopulated areas, but you can't use them to short-space an analog TV station closer to another analog station than would otherwise be allowed.
They're treating digital differently. They seem to be allowing closer spacing if one or both of the stations involved are running less than maximum power, or if one or both use directional antennas. Looking at 73.622 (
http://edocket.access.gpo.gov/cfr_2007/octqtr/47cfr73.622.htm) it looks like most of the stations cited in this thread fall into these categories:
KSWO & KTVT: KSWO at 138kw/327m seems to be at maximum facilities for DTV channel 11. KTVT, on the other hand, should be able to run as much as roughly 47kw at their antenna height.
WLUK & WMSN: WLUK should be allowed roughly 100kw at 384m - their authorized power is 17.2kw. WMSN should be allowed roughly 60kw - their authorized power is 15kw and they have a directional antenna.
WMTV, WGN, and WHOI: At 645kw/453m WGN seems to be at maximum allowable power. (they do have a directional antenna though that may be to avoid wasting power over Lake Michigan) WMTV, 155kw/415m, should be able to get roughly 800kw. WHOI, at less than 300m HAAT, should be able to get the full 1000kw - but their authorized power is 195kw. And, they're directional.
I can't evaluate the two California stations because their HAATs are so high, they don't appear on the charts in 73.622 and I don't have time to run the numbers through the formula...
I'm not going to say any of these are a good idea, but I do see how they got through the Commission.
Seriously, there's a 20 mile swath from the middle of Ellis County to the northern part of McLennan County where the two overlap. I suppose if you live there you can point your antenna to whichever station you want to get, but I suspect many or most of the people there get a confused receiver that decides to give them no picture at all.