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Why did some TV stations move from VHF to UHF in the DTV transition?

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Nelson
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Why did some TV stations move from VHF to UHF in the DTV transition?

Post by Nelson » Wed Nov 14, 2018 3:51 pm

Out of curiosity, why did some stations permanently move from VHF to UHF during the DTV transition? I don't see what the advantage is to UHF, especially in rural areas. Two examples that come to mind in northern Michigan are WPBN moving from 7 to 47 and WCML moving from 6 to 24.



Deleted User 14803

Re: Why did some TV stations move from VHF to UHF in the DTV transition?

Post by Deleted User 14803 » Wed Nov 14, 2018 7:24 pm

Because TV stations in the low vhf channel 2-6 are subject to more interference due to lower wavelengths and it would cause more problems with digital transmission more pixelated and drop outs .UHF is much better for digital transmission the only problem with HD TV over the air is signal coverage is not as large as analog.Techs are saying that when the new digital format comes out in a few years called ATSC 3.0 over the air TV reception inside your house and buildings will be more robust and not subject to as much interference



Arthur Mometer
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Re: Why did some TV stations move from VHF to UHF in the DTV transition?

Post by Arthur Mometer » Wed Nov 14, 2018 11:47 pm

A couple of other factors.

VHF ERPs allowed are too low due to flaws in the modeling and testing.

Most antenna elements used are too short for efficiently receiving VHF 7-13, and way to short for efficiently receiving VHF 2-6.

UHF cannot possibly bend over hills and the earth's curvature, which effectively obstructs signals like hills do, as well as VHF does. It's Physics, and cannot be changed, regardless of how the signal is sent, or detected, or the virtual channel number. Higher UHF ERP can improve this, if it overcomes noise levels, but literally only a few miles. The testimonials here and elsewhere as to how great their reception is are people at high receiver altitudes and LOS service with unblocked Fresnel Zones, or in very flat areas of terrain.

If they start using VHF 2-6 a lot, invest in Reynolds Aluminum.


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Arthur Mometer
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Re: Why did some TV stations move from VHF to UHF in the DTV transition?

Post by Arthur Mometer » Thu Nov 15, 2018 1:16 am

Forgot WPBN-TV on 7. This was due to WLS-TV, WOOD-TV, and WPBN-TV all ending up on Channel 7. WPBN-TV was prevented from using more than 500 watts nondirectional from the Harrietta site, so they had to go to UHF and a translator in Traverse City. WOOD-TV was originally analog Channel 7, but went to Channel 8 to relieve short spacing to WBKB, now WLS-TV. That opened up Channel 7 for Traverse City. It became a problem when all three were on Channel 7.


"I'm meteorologist Arthur Mometer."

"Those of you who think you know everything are very annoying to those of us who do."

"Lies have to be repeated and repeated to be believed. Truth stands on its own merit."

innate-in-you
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Re: Why did some TV stations move from VHF to UHF in the DTV transition?

Post by innate-in-you » Thu Nov 15, 2018 10:04 am

During the DTV transition phase (1998-2009), Telecasters simulcast analog and digital television services.
WOOD-TV analog was on channel 8, so it obviously could not transmit in ATSC on 8 (the two transmissions would jam each other), so WOOD-DT started on channel 7 (an ATSC signal is spread out over the whole channel and looks like snow, and power levels are lower, so interference to WPBN and WLS was not as bad as one would assume).
When WOOD-TV did the analog shutoff, that left channel 8 available to WWMT.
Since WPBN was co-channel to WOOD-TV, and both were DTV, it produced a conflict. WPBN was hit with a power level of 500w. WPBN was essentially robbed of its channel by WOOD-TV, and wound up moving its transmitter to Kalkaska, and to the UHF band.

It would have made sense for WOOD to take a UHF channel and have WPBN on channel 7 with tens of kilowatts of power (as WOOD has more urban viewers, and WPBN has more rural viewers - with all-channel outdoor antennas).



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