Very high frequency (VHF) is the radio frequency range from 30 MHz to 300 MHz. Radio frequency ( RF) is a Frequency or rate of Oscillation within the range of about 3 Hz to 300 GHz The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Frequencies immediately below VHF are denoted High Frequency HF, and the next higher frequencies are known as Ultra high frequency (UHF). High frequency (HF radio frequencies are between 3 and 30 MHz.
Common uses for VHF are FM radio broadcast, television broadcast (together with UHF), Amateur Radio, marine communications, air traffic control communications and terrestrial navigation systems (VOR in particular). See also Frequency modulation, FM band FM broadcasting is a broadcast Technology invented by Edwin Howard Armstrong that Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic Amateur radio, often called ham radio, is both a Hobby and a service in which participants called "hams" use various types of Radio communications Marine VHF radio is installed on all large ships and most motorized small craft Air traffic control ( ATC) is a service provided by ground-based controllers who direct Aircraft on the ground and in the air This article is about the radio navigation aid see VOR for other uses
VHF propagation characteristics are ideal for short-distance terrestrial communication, with a range generally somewhat farther than line-of-sight from the transmitter (see formula below). Radio propagation is a term used to explain how Radio waves behave when they are Transmitted, or are propagated from one point on the Earth Unlike high frequencies (HF), the ionosphere does not usually reflect VHF radio and thus transmissions are restricted to the local area (and don't interfere with transmissions thousands of kilometres away). VHF is also less affected by atmospheric noise and interference from electrical equipment than lower frequencies. Whilst it is more easily blocked by land features than HF and lower frequencies, it is less bothered by buildings and other less substantial objects than UHF frequencies.
Two unusual propagation conditions can allow much farther range than normal. The first, tropospheric ducting, can occur in front of and parallel to an advancing cold weather front, especially if there is a marked difference in humidities between the cold and warm air masses. TV DX and FM DX are two terms customarily grouped together that refer to long-distance reception of TV and FM Radio stations respectively A duct can form approximately 250 km (155 mi) in advance of the cold front, much like a ventilation duct in a building, and VHF radio frequencies can travel along inside the duct, bending or refracting, for hundreds of kilometers. For example, a 50 watt Amateur FM transmitter at 146 MHz can talk from Chicago, to Joplin, Missouri, directly, and to Austin, Texas, through a repeater. Chicago (ʃɪˈkɑːgoʊ is the largest City by population in the state of Illinois and the American Midwest of the United States. Joplin is a city in southern Jasper County and northern Newton County in the southwestern corner of the U In a July 2006 incident, a NOAA Weather Radio transmitter in north central Wisconsin was blocking out local transmitters in west central Michigan, quite far out of its normal range. NOAA All Hazards Weather Radio is a network of Radio stations broadcasting continuous weather information directly from a nearby National Weather Service (NWS The second type, much more rare, is called Sporadic E, referring to the E-layer of the ionosphere. Sporadic E or Es is an unusual form of Radio propagation utilizing characteristics of the earth's Ionosphere. A sunspot eruption can pelt the Earth's upper atmosphere with charged particles, which may allow the formation of an ionized "patch" dense enough to reflect back VHF frequencies the same way HF frequencies are usually reflected (skywave). Skywave is the propagation of electromagnetic waves bent (refracted back to the Earth's surface by the Ionosphere. For example, KMID (TV Channel 2; 54–60 MHz) from Midland, Texas was seen around Chicago, pushing out Chicago's WBBM-TV. KMID is the ABC affiliate in Midland - Odessa, Texas, owned and operated by Nexstar Broadcasting Group headquartered in Irving Midland is a city in and the County seat of Midland County located on the Southern Plains of the western area of the U Chicago (ʃɪˈkɑːgoʊ is the largest City by population in the state of Illinois and the American Midwest of the United States. WBBM-TV, channel 2 is the CBS owned and operated Television station in Chicago, Illinois. These patches may last for seconds, or extend into hours. FM stations from Miami, Florida; New Orleans, Louisiana; Houston, Texas and even Mexico were heard for hours in central Illinois during one such event. New Orleans (nʲuːˈɔrliənz nʲuːˈɔrlənz French: La Nouvelle-Orléans) is a major United States port city and the largest city in Louisiana The United Mexican States ( or commonly Mexico (ˈmɛksɪkoʊ () is a federal constitutional Republic in North America. The State of Illinois ( roughly ill-i-NOY is a state of the United States of America, the 21st to be admitted to the Union. Mid summer 2006 central Iowa stations were heard in Columbus, NE and blocking out Omaha radio and TV stations for several days. The State of Iowa ( is a state in the Midwestern region of the United States of America. Columbus is a city in Platte County, Nebraska, United States, 80 miles (148 km west by north of Omaha on the Loup River, a short
The large technically and commercially valuable slice of the VHF spectrum taken up by television broadcasting has attracted the attention of many companies and governments recently, with the development of more efficient digital television broadcasting standards. Digital television (DTV is the sending and receiving of moving images and sound by discrete ( digital) signals in contrast to the analog signals used by In some countries much of this spectrum will likely become available (probably for sale) in the next decade or so (currently scheduled for 2009 in the United States). This article is about the year For the film see 2009 Lost Memories. The United States of America —commonly referred to as the
VHF transmission range is a function of transmitter power, receiver sensitivity, and distance to the horizon, since VHF signals propagate under normal conditions as a line-of-sight phenomenon. Line-of-sight propagation refers to Electro-magnetic radiation including light emissions traveling in a straight line
An approximation to calculate the line-of-sight horizon distance is:
The VHF TV band in Australia was originally allocated channels 1 to 10 - with channels 2, 7 and 9 assigned for the initial services in Sydney and Melbourne, and later the same channels were assigned in Brisbane, Adelaide and Perth. In Telecommunication, radio horizon is the locus of points at which direct rays from an antenna are tangential to the surface of the Earth Other capital cities and regional areas used a combination of these and other frequencies as available.
By the early 1960s it became apparent that the 10 VHF channels were insufficient to support the growth of television services. The 1960s decade refers to the years from the beginning of 1960 to the end of 1969 This was rectified by the addition of three additional frequencies - channels 0, 5A and 11. Older television sets required adjustment to enable tuning to the new channels.
Several TV stations were allocated to VHF channels 3, 4 and 5A, which were within the FM radio bands although not yet used for that purpose. A couple of notable examples were NBN Newcastle, WIN-4 Wollongong and ABC Illawarra on channel 5A. NBN Television is a Television station based in Newcastle New South Wales, Australia The Newcastle metropolitan area is the second most populated area in the state of New South Wales and includes most of the Newcastle and Lake Macquarie WIN Television is an Australian television network owned by the WIN Corporation that is based in Wollongong, New South Wales Australia The Australian Broadcasting Corporation, commonly abbreviated to the 'ABC' is Australia's national public broadcaster. The Illawarra is a region in the Australian state of New South Wales. Most TVs of that era were not equipped to receive these broadcasts, and so were modified at the owners' expense to be able to tune into these bands; otherwise the owner had to buy a new TV. Beginning in the 1990s, the Australian Broadcasting Authority began a process to move these stations to UHF bands to free up valuable VHF spectrum for its original purpose of FM radio. The 1990s collectively refers to the years between and including 1990 and 1999 In addition, by 1985 the federal government decided new TV stations are to be broadcast on the UHF band.
Two new VHF frequencies, 9A and 12, have since been made available and are being used primarily for digital services (eg. ABC in capital cities) but also for some new analogue services in regional areas. The Australian Broadcasting Corporation, commonly abbreviated to the 'ABC' is Australia's national public broadcaster.
In New Zealand, the four main Free-to-Air TV stations still use the VHF Television bands (Band I and Band III) to transmit their programmes to New Zealand households. Band II is the name of a Radio frequency range within the Very high frequency part of the Electromagnetic spectrum. Band III is the name of a Radio frequency range within the Very high frequency part of the Electromagnetic spectrum. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island Band I is the name of a Radio frequency range within the Very high frequency part of the Electromagnetic spectrum. Band III is the name of a Radio frequency range within the Very high frequency part of the Electromagnetic spectrum. Other stations, including a variety of pay and regional free-to-air stations, broadcast their programmes in the UHF band, since the VHF band is very overloaded with four stations sharing a very small frequency band. In some areas, the band is so overcrowded, that the fourth television channel is not available. C4 is a Television station operating in New Zealand and owned by MediaWorks NZ.
British television originally used VHF band I and band III. Band I is the name of a Radio frequency range within the Very high frequency part of the Electromagnetic spectrum. Band III is the name of a Radio frequency range within the Very high frequency part of the Electromagnetic spectrum. Television on VHF was in black and white with 405-line format (although there were experiments with all three colour systems—NTSC, PAL, and SECAM—adapted for the 405-line system in the late 1950s and early 60s). The 405-line Monochrome analogue Television broadcasting system was the first fully electronic television system to be used in regular broadcasting NTSC ( National Television System Committee) is the Analog television system used in the United States, Canada, Japan, Mexico PAL, short for Phase Alternating Line, is a colour -encoding system used in Broadcast television systems in large parts of the world SECAM, also written SÉCAM ( Séquentiel couleur à mémoire, French for "Sequential Color with Memory" is an analog color television system
British colour television was broadcast on UHF (channels 21–69), beginning in the late 1960s. The 1960s decade refers to the years from the beginning of 1960 to the end of 1969 From then on, TV was broadcast on both VHF and UHF (VHF being a monochromatic downconversion from the 625-line colour signal), with the exception of BBC2 (which had always broadcast solely on UHF). The last British VHF TV transmitters closed down on January 3, 1985. Events 1431 - Joan of Arc is handed over to the Bishop Pierre Cauchon. Year 1985 ( MCMLXXXV) was a Common year starting on Tuesday (link displays 1985 Gregorian calendar) VHF band III is now used in the UK for digital audio broadcasting. Band III is the name of a Radio frequency range within the Very high frequency part of the Electromagnetic spectrum. Digital Audio Broadcasting ( DAB) also known as Eureka 147, is a Digital radio technology for Broadcasting Radio stations used in
Unusually, the UK has an amateur radio allocation at 4 metres, 70-70. Amateur radio, often called ham radio, is both a Hobby and a service in which participants called "hams" use various types of Radio communications 5 MHz.
Frequency assignments between US and Canadian users are closely coordinated since much of the Canadian population is within VHF radio range of the US border. Certain discrete frequencies are reserved for radio astronomy. Radio astronomy is a subfield of Astronomy that studies celestial objects at radio frequencies. The general services in the VHF band are:
In some countries, particularly the United States and Canada, limited low-power license-free operation is available in the FM broadcast band for purposes such as micro-broadcasting and sending output from CD or digital media players to radios without auxiliary-in jacks, though this is illegal in some other countries. Amateur radio, often called ham radio, is both a Hobby and a service in which participants called "hams" use various types of Radio communications HAVE QUICK is a frequency-hopping system used to protect military UHF radio traffic A Compact Disc (also known as a CD) is an Optical disc used to store digital data, originally developed for storing digital audio This practice was legalised in the United Kingdom on 8 December 2006. 
87. 5-87. 9 MHz is a radio frequency which, in most of the world, is used for FM broadcasting. See also Frequency modulation, FM band FM broadcasting is a broadcast Technology invented by Edwin Howard Armstrong that In North America, however, this bandwidth is allocated to VHF television channel 6 (82-88 MHz). Very high frequency (VHF is the Radio frequency range from 30 MHz to 300 MHz. The audio for TV channel 6 is broadcast at 87. 75 MHz.
87. 9 MHz is normally off-limits except for displaced class D stations which have no other frequencies in the normal 88. 1-107. 9 MHz subband on which to move. So far, only 2 stations have qualified to operate on 87. 9 MHz: 10-watt KSFH in Mountain View, California and 34-watt translator K200AA in Sun Valley, Nevada. KSFH (879 FM) is a Radio station broadcasting a Active Rock format CSN International began broadcasting Christian radio over satellite on April 26th 1995 from KAWZ in Twin Falls, Idaho. Sun Valley is a Census-designated place (CDP in Washoe County, Nevada, USA