cvoptimus

bicker

It is a bit more complex than this, but essentially, some stations made choices that resulted in weaker signals because it will save them money.

Now for the more detailed answer:

The vast majority of channels were broadcasting on UHF prior to June 12. UHF channels require a couple of orders of magnitude more power to transmit over the same distance as VHF channels require. A UHF channel broadcasting at 1000 kW ERP reaches just about as far as a VHF channel broadcasting at 30 kW ERP. So many channels elected to move back to their old VHF channel, once they turned off their analog signals, to reduce their electricity bill by 97%.

The problem with that is that digital signals are subject to a lot more interference on VHF, and are generally less reliable. Furthermore, the FCC was very conservative in authorizing higher power allocations on VHF, to try to keep co-channel interference to a minimum.

There is hope. The FCC is already working with some of the channels that made this bone-headed decision to go back to VHF, to see if they grant them a little bit more power or otherwise authorize some other construction that will alleviate the problem a bit.

However, personally, I think those channels should admit they were wrong, and file for a permit to move back to UHF, before all the slots available are issued to other broadcasters.

Mr. Know it all

Actually Bicker is wrong

Most channels - 2 - 13 was VHF

VHF is very easy to pick up, but changes in frequency as it goes higher in range.

VHF TELEVISION FREQUENCIES

BAND CH # FREQUENCY BAND CH # FREQUENCY

VHF LOW 02 54-60 Mhz VHF HIGH 07 174-180 Mhz

VHF LOW 03 60-66 Mhz VHF HIGH 08 180-186 Mhz

VHF LOW 04 66-72 Mhz VHF HIGH 09 186-192 Mhz

VHF LOW 05 76-82 Mhz VHF HIGH 10 192-198 Mhz

VHF LOW 06 82-88 Mhz VHF HIGH 11 198-204 Mhz

VHF HIGH 12 204-210 Mhz

VHF HIGH 13 210-216 Mhz

UHF is line of sight and usually requires a outside antenna and also a televison aerial rotor because you have to have your antenna pointed in the right direction to receive it properly.

Mr. Know it all

Channel 2 - 6 were the easiest to receive because they were the lowest in frequency.

More than likely, you will need a UHF antenna to continue to receive all the local television stations with a antenna.

bicker

Welcome to DTVUSA.

I'm not sure where you got your impressions, but unfortunately you're incorrect. Most of the digital channel frequency changes last Friday were from UHF to VHF.

Again, I'm sorry, but you're mistaken.

HTNut

cvoptimus

Thanks Mr. Know it All, but I already have a UHF antenna. My antenna is designed for both UHF/VHF. Remember, I was receiving all the local digital channels with few problems until Saturday. So, what's the variable? My equipment hasn't changed, so it must be the way the channels are broadcast. So bicker's explanation seems to make sense.
And thank you HTNut, your map confirms what I have found on other sites. I should be receiving a strong, easy to capture signal from all the local channels and more (Even with the missing stations I get 45-50 OTA channels). The government site (DTV.gov) has a helpful map that will even show the direction the signals are transmitted from to my address. All the local stations in my area come from the same direction.
That lends even more weight to bicker's hypothesis. If all the local channels are transmitting from the same direction and only two channels vanished after the transition, two channels owned and operated by the same affiliate, it must have something to do with the strength of their signals.
I can only hope that the problem is widespread enough that the local affiliate will feel obligated to do something about it.
How about it readers? Anyone else in L.A. who's lost KTTV and KCOP after the transition?

alrightypewriter

Yep, I lost both KTTV and KCOP. I had my converter box and a UHF/VHF antenna for months now and I was receiving both channels without a problem until the transition on Friday. I am still getting all of the channels I had before and these are the only 2 that disappeared. I'm in Glendale.

Piggie

This is what I called the "Hidden Transition". People that thought they were digital ready got a rude surprise Friday when stations that temporarily digital on UHF cut back to their old VHF channel on June 12th for the permanent digital channel.

KTTV went from 1000 KW on UHF CH66 to thinking 12 or so was enough on VHF. Doesn't work that way. They have applied for 112 KW which should match their old UHF range then some back on Ch11. When they get approved I bet they will try and up the power ASAP.

KCOP went from 371 KW on UHF Ch65 to thinking 12 KW on a temp auxilary tower was enough but have been granted a construction permit back to their main tower at 120 KW.

Both stations were forced to move of channels in the 60's that are no longer TV channels after Friday.

You will have to contact the station to find when they will be at full post transition power. And it appears KTTV has yet to get FCC approval where KCOP does have approval to construct.

__________________
The more I understand, the less I know.

Piggie

Most now agree that 40 KW is a minimum VHF power, but closer to 50 to 60 KW is better.

Most VHF stations have an over all gain of about 5 db, so if they want 50 KW they need a TPO of about 16KW to get 50KW ERP

Most UHF stations are at least 8 to 10 db of system gain. This means they need a TPO of 100 to 160 KW to achieve 1000 KW ERP.

That gives a savings of a 85 to 92 % savings in power, still significant, including the fact that at UHF transmitters are not as efficient as at VHF.

In many places such as Los Angeles there are no more UHF channels. NE corridor of the US is in the same boat. No more channels. They can't move back in some area's to their UHF.

The example above they can't move back to channels 65 and 66 as those are no longer even TV channels.

__________________
The more I understand, the less I know.