From a practical point of view, I totally agree. The Channel Master 777x is great. Might I add a little something here? If you are going to purchase a CM pre-amp, make it 7777. This is the VHF/UHF version. My reasoning is that, in the future, many of the UHF digital channels will revert to their old VHF channels. An example of this is that KGO in San Francisco which has it's analog on channel 7 and it's digital on channel 24 will revert to channel 7 as the digital channel when they shut off the analog signal.
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The signal does not become digital until it is demodulated. Before then it is an analog signal embedded in a sea of thermal noise, thunderstorm noise, appliance noise, galactic noise, planet Jupiter noise, and a few others. But for UHF, most of the noise originates in the first transistor.
My reading of the FCC web site is that none of the VHF frequencies will be reclaimed. Thus in 2007 nearly all stations with a VHF channel will abandon UHF.
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I understand the transmission is of course analog. I'm talking about the relevance to the end result on a persons TV screen. Doesn't "noise" affect an analog TV but not a "digital" TV - or NOT ? I don't understand your last sentence on the post.
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In 2007 (allegedly) they will "abandon" UHF for VHF...Well please educate me, WHY ??? What does VHF offer that UHF doesn't? It seems that UHF channels tend to come in better where I live, both analog and digital. Is VHF "better", why? Why would someone who runs a TV station spend money to go from UHF to VHF?
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Mike: This noise does not show up in the image, but it will cause dropouts and ultimately determines whether you can receive a station. The experiment I settled on was to put an accurately calibrated variable attenuator between the antenna and the amplifier, and adjust it to where dropouts just began. Then I would replace the amplifier with a 7775 and do it again. The difference in attenuator settings told which was better and by how much.
When the FCC first proposed abandoning VHF they thought the broadcasters would be pleased because UHF is much less affected by appliance noise than VHF. But the stations complained. The advantage of VHF is that it bends around corners better than UHF. Because of this the FCC allows UHF transmitters to have much higher power, but the stations say it is not enough.
If you live on a hilltop you will find UHF signals are very strong because of the higher power. But if you live behind a substantial hill you are much more likely to be successful getting VHF. There are some nice illustrations of this effect at http://www.hdtvprimer.com/ANTENNAS/siting.html .
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>>BobbyC - I thought the majority of DTV stations will use UHF<<
That may well be true, but the facts are the facts. KGO is planning on going back to channel 7 for their digital feed. An unsubstantiated thread that I've read is that channels 2-6 are not good prospects for digtial feeds but everything above that is fine. So, if your local station exists on channels 7-13, you may well see the digital feed transition back to the original analog channel.
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To supplement Ken's comments on VHF vs UHF I found the folowing link a month ago when I was trying to find out how far our CBS station could broadcast on Ch 19 using only 5Kw. Those of you with fringe reception might be interested in getting your station's broadcast parameters and see how far out you can expect to receive them according to FCC. Also I know very little about transmitters, but am interested. I found the calculator interesting.
Go to the Calculators which use the FCC propagation curves. Just to give one example:
Using a height of 1000 ft, a power of 1000Kw, a field of 60 dbu, and curve F(50,50) the following results on distance come out(the 2 decimals are just math, not reality):
Low VHF (2-6) = 59.85 miles
High VHF (7-13) = 60.84 miles
UHF (14-69) = 47.84 miles
This confirms that it takes more electrical power to reach a given distance in UHF than VHF which is an extra operating cost. I am sure there are other factors too including hills, trees and buildings.
I think the formula must use some middle channel in each group, as I think there is a frequency effect that, at a fixed power, distance drops as frequency goes up, especially in the UHF band
Ken?.
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There is a calculator at fcc.gov that does the same thing. The two give completely different results. Both calculators look useless to me, at least for a TV owner. They assume every receiving antenna is behind an average hill and average obstacles. They assume you know how many millivolts your TV needs. I am at a loss to explain why the FCC thinks VHF-high goes farther than VHF-low. It might be because of interference to VHF-low from electrical machinery or the occasional ionospheric propagation.
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I have a ChannelMaster 7777 (UHF/VHF) am because the company that I bought it from was out of the UHF only amps and gave me the same price (UHF gain was the same). I have a local station that will be broadcasting HD on channel 5 (yes, FIVE), so I might have to put up a VHF antenna in addition to my UHF CM 4228 to get all local HD stations. I still haven't decided if it's worth the effort since they don't have the decency to transmit on UHF. With Tropical Storm Bill coming in, I probably won't have a good enough signal to get much of anything for the next few days!! I hope it doesn't kill my new HD channels from DirecTV!
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Decency on UHF has nothing to do with the station, the FCC tells them what channel they are allowed to transmit on. You might have a pleasant surprise coming with your CM 4228. It picks up VHF reasonably well. I get channel 11 (digital)on mine (with the 7777) from 90 miles away. However, my picture on our local channel 5 (analog in the SF Bay Area) is very snowy unlike 7 (analog) which is pretty clean. Both of those channels are on the same tower.
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Yep, I know about 48-2, it holds up better than 12-1 for me and serves as a good back-up.
I'm thinking about the channel 3 dilemma in Chicago. It seems that the FCC doled out channel 3 for a station that broadcasts their analog on channel 4 and it has caused nothing but heartache for both the viewers and the station. The station says that the FCC mandated that channel and they could do nothing about it.
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The FCC for the first time is allowing adjacent channel TV stations, figuring that receivers are now good enough for that. But stations are learning that adjacent channels don’t work when there is a 10:1 power difference. I don’t know who is responsible for the fiasco in Chicago, but I thought it was the station for not buying a bigger transmitter. Their channel 3 is just 2500 watts. I am sitting beside my own 1500-watt transmitter.
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