Talk:Very high frequency

Ireland

Ireland uses VHF I believe. Can anyone add a few lines about this, if Im right?--Richy 20:03, 28 May 2005 (UTC)

Every one uses VHF, it is found in many devices you use every day.

OP is probably referring to VHF television broadcasting which was used in Ireland (and most of Europe) until 2012. The UK however discontinued its VHF television service in 1985. 81.151.248.58 (talk) 20:35, 21 November 2021 (UTC)

Line of Sight?

What do the line of sight equations have to do with VHF? I'll delete in the morning if no explanation comes up. MooCreature 03:56, 14 February 2006 (UTC)

VHF range is line-of-sight, so the equations are directly relevant, giving the range available for a given antenna height. Do not delete. If anything, a word of explanation is all that is needed. Graham 03:54, 14 February 2006 (UTC)

Doesn't the formula for line of sight evaluate in nautical miles, not miles?

Line of Sight

Points to note

When using height in feet, the range will be in nautical miles. The formula shown for range is a rule of thumb and is also incorrect. It shows the square root of (1.5 x height). It is in fact 1.5 x (sqrt of transmitter height). The more accurate formula is 1.25 x (sqrt of transmitter height + sqrt of receiver height)

Neil Gascoigne 15 Aug 2006

Given that the radius of the earth is 6373 km, and a mile is 5280 feet or 1609.344 metres, the asymptotically correct formula for the distance to the horizon in miles is sqrt(2 × 6373/1.609344 × height in feet/5280), or sqrt(1.50000 × height in feet). A remarkable coincidence, based on the fact that 5280²×2.54×12×3/4 = 637300224. The distance in km to the horizon is sqrt(12.746 × height in metres). Eric Kvaalen (talk) 07:15, 24 July 2009 (UTC)

The formulas in this article give the same distance to the horizon as the formula in the Horizon article. The VHF horizon is not the same as the visual horizon due to slight bending by the atmosphere. http://www.moonraker.com.au/techni/vhfrange.htm modifies these formulas to be 1.415 x sqrt(height in feet) and 4.124 x sqrt(height in metres).--Spuzzdawg (talk) 06:48, 28 July 2013 (UTC)

When?

When did the Sporadic-E event happen in Central Illinois? I'm sure that was a surprise to many living there. --66.153.178.253 23:36, 23 October 2006 (UTC)

I don't think it was specifically mentioned that it was Sporadic_E_propagation, it may very well have been TV_and_FM_DX#Tropospheric_ducting --Kielhofer (talk) 08:32, 23 October 2008 (UTC)

88-92 non-commercial???

it says that FM 88-92 are reserved for non-commerical stations in the United States but i live in the detroit area and there are commercial stations that broadcast in this range. Can someone please provide an explanation of a non-commercial station or edit the page accordingly? —The preceding unsigned comment was added by 68.248.43.122 (talk) 06:19, 5 January 2007 (UTC).

The FCC has set aside certain frequencies for noncommercial educational FM broadcasting.

The whole list can be found in 47 CFR 73.501. The frequencies range from 88.1 to 91.9 with the decimal portion being an odd number (e.g. 88.1, 88.5, 90.3).--Kielhofer (talk) 08:23, 23 October 2008 (UTC)

Perhaps the stations the OP hears are pirates or Canadian ? 81.151.248.58 (talk) 20:36, 21 November 2021 (UTC)

move paragraph

I think the paragraph that is in the introduction about the ducts should be moved to the actual content, under its own heading. It doesn't add much to the introduction, which is supposed to give a general overview about the subject...

TV channel 6 over fm radios

Can someone who is knowledgeable about this add something (hopefully sourced) about how TV VHF channel 6 audio can be heard on the low end (~ 88 MHz) of FM radios. As anyone else experienced this? THis was the origin of TV on the Radio's band name, I presume as well. THis sentence is a good start: (but more could be put in.) "In North America, however, this bandwidth is allocated to VHF television channel 6 (82-88MHz). The audio for TV channel 6 is broadcast at 87.75 MHz." Thanks. --Rajah 21:49, 31 July 2007 (UTC)

Subsection 'United States, Canada, and North America'

Could someone please have a look at this subsection title and make sure it's correct? To me it looks like it could be worded better (as far as I know, the only country in North America besides the US and Canada is Mexico), but I might be missing some fine cultural differences between European and North American approach so I'll leave it to the North Americans to decide. —Preceding unsigned comment added by 203.173.228.64 (talk) 03:11, 22 March 2008 (UTC)

North America actually contains all the countries down through Panama as well, including most of the islands in the Caribbean. But yes, this headline is very redundant and almost stupid-sounding since the US and Canada are in North America. = ∫_t^c 5th Eye 00:51, 9 May 2008 (UTC)

72-76 MHz

Actually 75 MHz is reserved worldwide as an aeronautical navigation frequency for use as Marker_beacon.

Normally the "guard"band for this frequency goes from 74.8 - 75.2 MHz to keep the marker beacons free from interference.

In the US frequencies in the 72-76 MHz band, excluding the guard band, has been used for low power paging and GPS based Slave_clock.

Kielhofer 20:56, 30 July 2010 (UTC)

VHF Line of Sight Calculation

This doesn't work any more in the United States: the FCC is admitting it messed up because many people are having difficulty picking up even channels 7-13. Channels 2-6 are even worse. This article needs a section on VHF problems in the digital TV era.Vchimpanzee · talk · contributions · 17:45, 24 June 2009 (UTC)

Okay, someone feels the source doesn't say that. Will rewording help?Vchimpanzee · talk · contributions · 17:48, 23 September 2009 (UTC)

Wavelength

What is the wavelength of these frequencies; in the Ultra high frequency page; it conveniently says right in the beginning. Daniel Christensen (talk) 13:28, 3 November 2009 (UTC)

Find out the info, dear sir, and add it. That's what wikipedia is about. To my humble understanding, at least. Wishing you every success, Jan olieslagers (talk) 21:23, 18 June 2010 (UTC)

Aviation use

The current version suggests that the use of VHF frequencies for voice communication and navaids is limited to North America; however these frequencies are used all round the globe. How to best improve the page to this effect? Jan olieslagers (talk) 20:18, 18 June 2010 (UTC)

87.9 MHz

The article mentions 87.9 MHz is normally off-limits for FM audio broadcasting except for displaced class D stations. What exactly does this class D mean? — Preceding unsigned comment added by A-v-S (talk • contribs) 15:39, 24 May 2011 (UTC)

Line of sight calculation

Is that the calculation of the antenna's length, or it's tip's distance from the ground(as in surface, not electrical). 72.79.135.3 (talk) 19:30, 12 July 2014 (UTC)

A_f is the height of the antenna above the ground. --Chetvorno^TALK 19:56, 12 July 2014 (UTC)

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VHF television

There appears to be a serious error in this section.

I don't know about other countries. However, in the USA, only VHF channels 2 through 6, the low band with frequencies lower than the FM band were eliminated for TV use. Channels 7 through 13 are still used for digital broadcast TV. I receive ABC on channel 9.

Someone needs to fix this error.

Tyrerj (talk) 00:50, 31 October 2016 (UTC)

Wavelength range in infobox

Is it just me, or does anyone else think that putting the wavelength range in reverse order is not useful? When it's written as a conversion like "30 MHz to 300 MHz (10 to 1 m)" for instance then it makes sense. But in the infobox where they are two separate fields then it is just confusing. SpinningSpark 14:08, 30 July 2021 (UTC)