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Please don't treat this page as a doubt page for your questions about UHF in general. This page is meant for discussions about the article itself. Cheers. Unstudmaddu ( talk) 13:21, 7 July 2008 (UTC)
Many of the terms in the list of frequency allocations in the US need to be linked. What is an A&B Franchise, anyway? -- Beland 08:12, 27 Dec 2004 (UTC)
In this article we read: As well, the layer of the Earth's atmosphere called the ionosphere is filled with charged particles that can reflect radio waves. This can be helpful in transmitting a radio signal, since the wave bounces from the sky to the ground over and over, covering long distances. However, UHF benefits less from this effect than lower (VHF, etc.) frequencies. So, as I undestand it, UHF doesn't bounces alot. At least, it bounces less than VHF (as it benefits less etc.), so UHF transmisions is more likely to escape into space. But when I turn to the VHF article, I read: Unlike high frequencies (HF), the ionosphere does not usually reflect VHF radio and thus transmissions are restricted to the local area So, VHF transmissions are not bouncing at all. Is this a contradiction in these two articles, or the meaning is that both waves bounces very little? My question originate from the news that astronomers will look for tv transmissions in other planets. Do actually VHF and UHF waves can make it into space?
To work ISS, you wouldn't want the signal to be bounced back to the ground by a layer of the ionosphere - you would want it to go straight through and continue into space. To do this, you need to be above the maximum usable frequency for signals to bounce back down - so a VHF or UHF frequency would usually be suitable, while an HF frequency would be a poor choice. Basically, this is the opposite of the frequency choices made if you intended to CQ DX to a terrestrial station. -- 66.102.80.212 ( talk) 15:38, 20 December 2009 (UTC)
Well, I think this page should now be largely understandable to someone without a background in broadcast engineering. Removed cleanup-technical tag. Still don't know what A&B franchise is though -- I'll have to come back to it with a full copy of the US frequency allocation table. Wordie 19:04, 21 Jan 2005 (UTC)
I changed AMPS to Cellular on the USA chart, since the analog AMPS format was discontinued by the major national carriers on 18 Feb 2008 (some smaller carriers may still use it in remote rural areas). I also cleaned up some other minor inaccuracies on the United States chart. —Preceding unsigned comment added by 144.230.63.56 ( talk) 07:49, 16 June 2009 (UTC)
As a licenced ham i have become aware of the complexities of operating uhf on low power (qrp) from a distance eg i am able on just five watts output to access a repeater on Olivers Mount from approx 15 miles distance just be placing my car within distance of a PL (power line). Taking into consideration the topography between Brompton and Scarborough and i have proved that its not possible to access this repeater away from a power line so its my intention to learn just how far PLT can assist us Hams to work qrp from considerable distances on uhf.G6XCJ.
M3HSE. Chris 1127 12:10, 2 January 2006 (UTC)
SPACE: It may be of interest that using only 10w on 145.825Mhz simplex i am able to frequently have comms with Sats travelling at 1570MPH including the space station itself from a co-linear mounted just 6ft from ground! No problems.
EME:Is now my next venture but first i must talk to a lad who is in regular qso with ZL & VK. G6XCJ/G0CJM —Preceding unsigned comment added by 88.105.108.56 ( talk) 19:19, 4 August 2009 (UTC)
Anybody care to comment on what happened to channels 70-83 in the US a few years back? I don't know enough of the background to change the article.
I want to learn more about how video conferencing is carried out through mobiles.
One shouldn't need "digital technology" to be able to tune adjacent channels. The inability to do so was largely due to poor (or low-quality) tuner design in many of the earliest TV's. Any TV which can be connected directly to cable television would need to be able to handle adjacent channels of equal strength (originally on VHF, although some cable block converters did move midband/superband channels onto UHF so that "cable 15" could land somewhere around UHF 50). Nonetheless, the spacing of channels (six degrees of separation) continued through the 1980's and beyond (Kingston, Ontario got 32 and 38 as its two local UHF channels in the mid-1980's). The absurdly-wide frequency spacings between UHF channels in local communities should have been scrapped years ago, as pushing stations way up the dial to maintain UHF taboo spacings was making other problems (such as propagation over terrestrial obstacles) much worse. Yet this is only being abandoned now as part of digital television transition, as new tuners will be needed for digital TV in any case and the double conversion receivers used for the original DTV test had no issues with adjacent-channel or image-frequency rejection.
25% efficiency in frequency re-use between cities (so one city only had 3 of the 12 possible VHF channels) is common, though, and to be expected in anything other than a single-frequency network. You mention Rochester (8, 10, 13)? If it can't overlap Syracuse (3, 5, 9) Kingston/Watertown (6, 7, 11) Peterborough (12) Toronto/Hamilton (5, 9, 11) or Buffalo (2, 4, 7) - all situated around Lake Ontario - then those three are all that's left. All too typical, much like colouring a political map without giving two adjacent regions the same colour requires a minimum of four colours, covering a region with TV requires four times as many possible channels as actual networks to be carried. Two adjacent cities can't use the same full-power channels without short-spacing problems (13 Albany to 13 Newark NJ is short-spaced, for instance). Ottawa (4, 9, 13) has used low-power stations (6, 11) which otherwise would be short-spaced to Montréal and Kingston (respectively) but the results leave much to be desired. An underpowered analogue station is very snowy very quickly. -- 66.102.80.212 ( talk) 20:21, 28 December 2008 (UTC)
There is info in other articles, SECAM perhaps, regarding the switch from 828-line VHF to 625-line UHF images for TV in France. Should any of this be referenced, or at least linked, from this article? -- carlb 02:31, 17 March 2006 (UTC)
authors have it hidden. — Preceding unsigned comment added by 5.12.37.48 ( talk) 22:27, 20 December 2020 (UTC)
There's a section entitled "advantages", should there be one entitled "disadvantages"? or would this merely repeat info such as the line-of-sight propagation pattern which is already described elsewhere here? -- carlb 02:34, 17 March 2006 (UTC)
The GPS also works in the UHF range, specifically at 1575.42 MHz and 1227.6 MHz.
At the moment, there is a notation that US TV Channel 34 is reserved for radar use, with a "citation needed" mark. I haven't found definite proof either way, but a quick [ Google] shows at least two stations on or approved for channel 34, KNIC-CA and KMCC. The [ spectrum chart] from the Department of Commerce does note the special use for channel 37, but has no special notation for channel 34. 70.185.217.138 10:46, 15 June 2007 (UTC)
should it be mentioned how the us has made it illegal to sell scanners with tunable cell phone frequencies but that it is not illegal to own one or bring one in from another country? This is the only part of the electromagnetic spectrum that is restricted in this way. --Great Zarquon
Clarins are selling a new facial spray called Expertise 3P, which claims to protect the skin from the harmful effects of electromagnetic waves, specifically those "produced by different types of domestic communications equipment". They claim to have grown skin cells in the lab and exposed them to 900 MHz (signal strength not given) and seen changes in the skin cells. The ingredients in this spray are claimed to reduce the changes. Unfortunately this is not published yet but is it remotely plausible that our skin is being damaged daily by mobile phone and TV signals etc?! —The preceding unsigned comment was added by Purple ( talk • contribs) 17:22, 20 February 2007 (UTC).
Drat; I was unclear about Image frequency rejection, so now someone who knows no radio theory has turned it upside down. Making it a link would help some, but that's a rather theory-heavy little article and I am unable to find an article that explains in simple terms what a double-conversion superheterodyne radio tuner does for UHF television. So, it looks like I'll have to write that explanation as a paragraph or two in one of the articles that have to do with Intermediate frequency and then link from this UHF article to that one. Or maybe write a brand new UHF Taboo article. Moan, groan, always there's more stuff to explain to a world that doesn't know television is radio. Jim.henderson 22:14, 26 June 2007 (UTC)
Back in the 1970s, TV Guide ran an article on how UHF came into the American broadcast system. The FCC put a freeze on new construction permits for TV stations in 1948, and began studying how to provide communities across the country with a choice of local television services. They were interested in seeing if so-called "upstairs broadcasting" could be part of the system. The freeze dragged on for four years.
During the freeze, some broadcasters, including Dr. Allen B. DuMont, pleaded for "non-intermixture" - some areas would be all VHF, others all UHF, in order to allow equal opportunity between stations in a single market. That, however, would have meant some pioneer VHF stations would have to change, and station owners opposed being forced to change after pioneering a medium that was belittled by their contemporaries in the 1940s.
When the FCC lifted the freeze in 1952, they ignored DuMont and others who made the same case, and issued a mix of channel allocations, though smaller cities tended to have more UHF channels than VHF. At the time, VHF-Lo stations were limited to 100 kW and VHF-Hi stations to 325 kW. The FCC allowed UHF stations a maximum of 1,000 kW, but nobody knew how to build a transmitter that powerful.
When the freeze was lifted, new applications poured in for TV stations, going after the VHFs where available, but quickly oversubscribed. Where VHFs were filled, the applicants went for UHF channels. Stations were built and went onto the air, but the UHFs generally got into trouble if they had to compete with VHF stations. One station only lasted three months before giving up, though one of the first, KPTV Portland, lasted 12 years before a merger moved the call sign to a VHF station.
The FCC tried some patchwork fixes. They boosted the maximum power to 5,000 kW, and changed corporate ownership rules: previously an entity could only own 5 TV stations (and 5 AMs and 5 FMs); the FCC raised it to 7 TV stations, as long as no more than 5 were VHF. NBC and CBS each bought two UHF affiliates, found them clobbered in the ratings (NBC bought WBUF Buffalo, running against WGR 2 and WKBW 7, for example) and shut them down.
FCC decided it had made a mistake and, in the words of the TV Guide article, decided to unscramble the egg by changing to de-intermixture. Several VHF stations would have to convert to UHF. The station owners put pressure on their congressmen, who put pressure on the FCC. Congress produced a compromise in 1962, the All Channel Law that came effective in 1964. All TV sets would now be required to have a built-in UHF tuner, although it ended up almost always being a radio-style tuner (inner knob coarse tuning, outer ring finer tuning) rather than clicking into individual channel positions as the VHF tuners (inner knob clicking to a channel, outer ring used for fine tuning). UHF stations started up in the mid to late 1960s tended to be more successful, though still relegated to the minor leagues and having to innovate by providing niche programming: sports, foreign language, business news, movies, etc.
By the early 1970s, manufacturers were required to provide click-type tuning for UHF, and this took different forms - miniature position click tuning, or a mechanical digital display (1-8 on the 10s disc, 0-9 on the 1s disc) where the knob turned numerous rotations as the tuner was worked from 14 to 83, but not directly between 83 and 14 (unlike 13 to 2 on the VHF dial). The final point of convenience for consumers, making the distinction invisible and making stations more-or-less equal (except in terms of signal reach and quality), started with Magnavox's "Random Access Tuning System", STAR, which allowed set users to simply push a two-digit sequence on their remote control, like dialing a two-digit phone number. This method of channel selection has become universal.
Some VCRs in the 1980s had push button channel positions (14 or 16, usually), and you would open a panel, select a band (VHF-Lo, VHF-Hi or UHF), then rotate a knob to move through the channels to find the one you wanted at a specific button, then change small plastic tabs to show the channel lit up in the tuner panel. This is probably the last vestige of distinction between television broadcast bands. GBC ( talk) 08:54, 2 November 2008 (UTC)
Much as I strive for correctness in the use of diacritical marks, I don't think we can justify the use of the spelling "México" in an English text, as this is essentially not merely a variant spelling, but rather a different name for the country altogether, one that we don't use in English. The country's English name is "Mexico", without the accent, and pronounced IPA: [ˈmeksɪkɜʊ]. "México", on the other hand, is the country's Spanish name, pronounced IPA: [ˈmexiko]. I have therefore removed the two instances of the name "México" and replaced them with "Mexico". Kelisi ( talk) 01:57, 16 February 2009 (UTC)
I notice that this article is dominated by television's use of the UHF band. I propose that UHF television be broken off into a separate article, with this article going into some high-level overview of the technical merits, historical discovery, and overall use of the UHF band around the world. Dinjiin ( talk) 00:08, 12 December 2009 (UTC)
I notice that a user has covered this page in maintenance tags; when I attempted to address the issue on his talk page he reverted me. The tags raised questions about intermixture and about HDTV. My understanding is that:
The article states that high channels were auctioned off. However, from a lay viewpoint, stations that used to be on, say, channel 60, now are on digital channel 60-1 without problem. The article should mention where on the spectrum high digital channels were reallocated to. This information is also missing from North American broadcast television frequencies, television channel frequencies, and frequency allocation. Were they required to use virtual channels? And, if so, where are they most commonly reallocated, or is it on a case-by-case basis? Calbaer ( talk) 19:07, 25 March 2010 (UTC)
The article mentions "UHF islands" mid sized markets located close to major cities where most/all local stations were UHF. However given their inherently longer range wouldnt VHF signals from the cities have overspilled into these markets ? How much of a problem did this cause for the (often newly established) local UHF stations attempting to compete with the (often longer established) big city stations. Particularly those which were affiliated to networks and therefore carrying largely similar programming ? 86.112.65.115 ( talk) 12:05, 8 August 2010 (UTC)
What is the transition's effect on UHF signals? I believe digital TV uses less UHF signals, but does it still use some UHF signals? Thanks for any responses.-- Wyn.junior ( talk) 04:10, 1 March 2014 (UTC)
Signal range is the actual distance the UHF signal travels. I would consider that most important.
Frequency range | 0.3 to 3 GHz |
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Wavelength range | 1 to 0.1 m |
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-- Wyn.junior ( talk) 04:07, 2 March 2014 (UTC)
User:Dr Greg deleted this sentence from the that I added: "UHF is used for digital television stations in the US."
His response for the deletion was: "copy edit last edit"
What would it matter if I made this edit or something similar to another page? Uf this info is true, then it is very significant and should be in the lede. And actually, I believe UHF is the standard for digital tv, not only in the US.
Thanks-- Wyn.junior ( talk) 16:06, 2 March 2014 (UTC)
"The FCC has allowed Americans to connect any device and any application to the 22 MHz of radio spectrum that people are calling the 700 MHz band. " I'm not entirely sure what this is trying to say, but "people are calling" is definitely not proper encyclopedic language. -- Khajidha ( talk) 14:59, 30 March 2020 (UTC)