Quote:
Originally Posted by NN5I
Thank you; now I understand a bit better. When you meant North American TV you wrote terrestrial TV instead. Naîve of me to suppose you would use the word that meant what you were trying to say. Forgive me; I'm a follower of Mark Twain, who once wrote "The difference between the right word and the almost-right word is the difference between the lightning and the lightning-bug." But actually I was uncertain whether NTSC and PAL were still in use anywhere. I still don't know. The only non-terrestrial TV I ever knew about was sent from the Moon by Apollo crews. I watched in awe when it was retransmitted via terrestrial (North American, NTSC) TV.
As for power cost comparisons between UHF and VHF TV, I understand you to say that, to achieve an equal footprint, one must run higher power than on VHF. I didn't know that, but have no reason to doubt it, and your explanation in terms of noise makes sense and is probably correct. Thanks for teaching. But first I had translate your use of noise to the standard engineering term spectral noise density, sometimes written noise spectral density with the same meaning. The second usage seems more precise to me but is a bit less common.
When, in your discussion of Channel 11, you refer to "the CW" I have no clue what you are talking about. That's not clearly enough expressed for old EEs like me.
Incidentally, you wrote "since you ask" but if you read it again you may see that I didn't ask. Careful reading is as important as careful writing, if communication is to be clear.
Cheers! Maybe we can talk about this stuff over a pizza some time. I'll buy. It'll be fun, because each of us knows stuff the other doesn't know.
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Terrestrial - means that it is broadcast through the air.
In today's world less then 30% of all television reception is done via terrestrial reception - due to the cable television and satellite television reception being the norm.
The type of digital broadcast is irrelevant - since we are not going to go to Europe or Japan to watch television in our motor homes.
Truthfully - the European standard was a much better type then the type we use in the USA - these decisions are made by the telecommunications Union - which the USA and Canada are a part of.
NTSC - never the same color twice - was an ancient way of broadcasting television. It was very inefficient - only allowed you to have one signal per a band - 6 Mhz of bandwidth..
The analog television transmitter was effectively two transmitters.
The video used a form of Vestigial Sideband ( 8VSB ) ( AM ) where most of the power was forced up into the one side band.
The audio was FM at a much lower power level, since FM did not have to over come the noise like the video did.
It's now possible to fit 5 channels into the same bandwidth as the one analog signal.
The CW is a television Broadcast Network, like Fox, NBC, ABC , CBS , ION etc.
http://www.cwtv.com/
http://en.wikipedia.org/wiki/Television_station
VHF stations often have very tall antennas due to their long wavelength, but require much less effective radiated power (ERP), and therefore use much less transmitter power output, also saving on the electricity bill .
In North America, full-power stations on band I (channels 2 to 6) are generally limited to 45 kW digital ERP.
Stations on band III (channels 7 to 13) can go up by 5dB to 160 kW digital.
UHF, by comparison, has a much shorter wavelength, and thus requires a shorter antenna, but also higher power.
North American stations can go up to 1000 kW digital.
Low channels travel further than high ones at the same power, but UHF does not suffer from as much electromagnetic interference and background "noise" as VHF, making it much more desirable for TV.
Digital television transmission more efficiently uses the available bandwidth and can easily integrate other digital services.
Digital television has the potential for resolutions and sound fidelity far higher than those of analogue broadcasts.
t is also possible to offer far more channels by way of digital multiplexing, and subchannels, distinct simulcast programming, from the same broadcaster.
The amount of sub channels a station provides and the quality of the primary channel, has an impact on the quality of the remaining sub channels.
Decreasing the bandwidth available to the existing channel(s) meaning overall lower picture quality due to compression artifacts and non-proportional anamorphic widescreen digital scaling.