 |
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2009) |
|
||||||||
|
Ultra-high frequency (UHF) designates the ITU radio frequency range of electromagnetic waves between 300 MHz and 3 GHz (3,000 MHz), also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres (10 cm to 1 metre). Radio waves with frequencies above the UHF band fall into the SHF (super-high frequency) and EHF (extremely high frequency) bands, all of which fall into the microwave frequency range. Lower frequency signals fall into the VHF (very high frequency) or lower bands. See Electromagnetic spectrum and Radio spectrum for a full listing of frequency bands.
Contents |
Characteristics, advantages, and disadvantages [link]
The point to point transmission and reception of TV and radio signals is affected by many variables. Atmospheric moisture; solar wind; physical obstructions, such as mountains and buildings; and time of day all affect the signal transmission and the degradation of signal reception. All radio waves are partly absorbed by atmospheric moisture. Atmospheric absorption reduces, or attenuates, the strength of radio signals over long distances. The effects of attenuation degradation increases with frequency. UHF TV signals are generally more degraded by moisture than lower bands, such as VHF TV signals. The ionosphere, a layer of the Earth's atmosphere, is filled with charged particles that can reflect some radio waves. Amateur radio enthusiasts primarily use this quality of the ionosphere to help propagate lower frequency HF signals around the world: the waves are trapped, bouncing around in the upper layers of the ionosphere until they are refracted down at another point on the Earth. This is called skywave transmission. UHF TV signals are not carried along the ionosphere but can be reflected off of the charged particles down at another point on Earth in order to reach farther than the typical line-of-sight transmission distances; this is the skip distance. UHF transmission and reception are enhanced or degraded by tropospheric ducting as the atmosphere warms and cools throughout the day.
The main advantage of UHF transmission is the physically short wave that is produced by the high frequency. The size of transmission and reception antennas is related to the size of the radio wave. The UHF antenna is stubby and short. Smaller and less conspicuous antennas can be used with higher frequency bands.
The major disadvantage of UHF is its limited broadcast range and reception, often called line-of-sight between the TV station's transmission antenna and customer's reception antenna, as opposed to VHF's very long broadcast range and reception, which is less restricted by line of sight.
UHF is widely used in two-way radio systems and cordless telephones, whose transmission and reception antennas are closely spaced. UHF signals travel over line-of-sight distances. Transmissions generated by two-way radios and cordless telephones do not travel far enough to interfere with local transmissions. Several public-safety and business communications are handled on UHF. Civilian applications, such as GMRS, PMR446, UHF CB, 802.11b ("WiFi") and the widely adapted GSM and UMTS cellular networks, also use UHF cellular frequencies. A repeater propagates UHF signals when a distance greater than the line of sight is required.
- See "Radio horizon".
Applications [link]
Television [link]
UHF television broadcasting fufilled the demand for additional over-the-air television channels in urban areas. Today, much of the bandwidth has been reallocated to land mobile, trunked radio and mobile telephone use. UHF channels are still used for digital television.
Radio [link]
UHF spectrum is used world-wide for land mobile radio systems for commercial, industrial, public safety, and military purposes. Many personal radio services use frequencies allocated in the UHF band, although exact frequencies in use differ significantly between countries.
Frequency allocation [link]
Australia [link]
- UHF Citizens Band: 300–3000MHz
Canada [link]
- 470–806 MHz: Terrestrial television (with select channels in the 700 MHz band left vacant)Now Verizon Wireless 4G network.
- 1452–1492 MHz: Digital Audio Broadcasting (L band)[1]
- Many other frequency assignments for Canada and Mexico are similar to their US counterparts
United Kingdom [link]
- 380–395 MHz: Terrestrial Trunked Radio (TETRA) service for emergency use
- 430–440 MHz: Amateur radio (ham – 70 cm band)
- 457–464 MHz: Scanning telemetry and telecontrol, assigned mostly to the water, gas, and electricity industries
- 606–614 MHz: Radio microphones and radio-astronomy
- 470–862 MHz: TV channels 21–69 (channel 36 used for radar, channel 38 used for radio astronomy, channel 69 used for licenced and licence exempt wireless microphones, channels 31–40 and 63–68 to be released and may be made available for other uses by Ofcom. Public consultation due December 2006)
- 1240–1316 MHz: Amateur radio (ham – 23 cm band)
- 1880–1900 MHz: DECT Cordless telephone
- 2310–2450 MHz: Amateur radio (ham – 13 cm band)
United States [link]
The Family Radio Service and General Mobile Radio Service use the 462 and 467 MHz areas of the UHF spectrum. There is a considerable amount of lawful unlicensed activity (cordless phones, wireless networking) clustered around 900 MHz and 2.4 GHz. These ISM bands – open frequencies with a higher unlicensed power permitted for use originally by Industrial, Scientific, Medical apparatus – are now becoming some of the most crowded in the spectrum because they are open to everyone.
The 2.45 GHz frequency is the standard for use by microwave ovens. The spectrum from 806 MHz to 890 MHz (UHF channels 70–83) was taken away from TV broadcast services in 1983, primarily for analogue mobile telephony. In 2009, as part of the transition from analog to digital over-the-air broadcast of television, the spectrum from 698 MHz to 806 MHz (UHF channels 52–69) was also no longer used for TV broadcasting. Channel 55, for instance, was sold to Qualcomm for their MediaFLO service, which is resold under various mobile telephone network brands. Some US broadcasters had been offered incentives to vacate this channel early, permitting its immediate mobile use.
The FCC's scheduled auction for this newly available spectrum was completed in March 2008.[2]
- 225–420 MHz: Government use, including meteorology, military aviation, and federal two-way use[3]
- 420–450 MHz: Government radiolocation and amateur radio (70 cm band)
- 433 MHz: Short range consumer devices including automotive, alarm systems, home automation, temperature sensors
- 450–470 MHz: UHF business band, General Mobile Radio Service, and Family Radio Service 2-way "walkie-talkies", public safety
- 470–512 MHz: TV channels 14–20 (also shared for land mobile 2-way radio use in some areas)
- 512–698 MHz: TV channels 21–51 (channel 37 used for radio astronomy)
- 698–806 MHz: Was auctioned in March 2008; bidders got full use after the transition to digital TV was completed on June 12, 2009 (formerly UHF TV channels 52–69)
- 806–824 MHz: Public safety and commercial 2-way (formerly TV channels 70–72)
- 824–851 MHz: Cellular A & B franchises, terminal (mobile phone) (formerly TV channels 73–77)
- 851–869 MHz: Public safety and commercial 2-way (formerly TV channels 77–80)
- 869–896 MHz: Cellular A & B franchises, base station (formerly TV channels 80–83)
- 902–928 MHz: ISM band, amateur radio (33 cm band), cordless phones and stereo, radio-frequency identification, datalinks
- 929–930 MHz: Pagers
- 931–932 MHz: Pagers
- 935–941 MHz: Commercial 2-way radio
- 941–960 MHz: Mixed studio-transmitter links, SCADA, other.
- 960–1215 MHz: Aeronautical Radionavigation
- 1240–1300 MHz: Amateur radio (23 cm band)
- 1452–1492 MHz: Military use (therefore not available for Digital Audio Broadcasting, unlike Canada/Europe)
- 1710–1755 MHz: AWS mobile phone uplink (UL) Operating Band
- 1850–1910 MHz: PCS mobile phone—order is A, D, B, E, F, C blocks. A, B, C = 15 MHz; D, E, F = 5 MHz
- 1920–1930 MHz: DECT Cordless telephone
- 1930–1990 MHz: PCS base stations—order is A, D, B, E, F, C blocks. A, B, C = 15 MHz; D, E, F = 5 MHz
- 2110–2155 MHz: AWS mobile phone downlink (DL) Operating Band
- 2300–2310 MHz: Amateur radio (13 cm band, lower segment)
- 2310–2360 MHz: Satellite radio (Sirius and XM)
- 2390–2450 MHz: Amateur radio (13 cm band, upper segment)
- 2400–2483.5 MHz: ISM, IEEE 802.11, 802.11b, 802.11g, 802.11n Wireless LAN, IEEE 802.15.4-2006, Bluetooth, Radio-controlled aircraft, Microwave oven, ZigBee
See also [link]
- All-Channel Receiver Act
- Australasian television frequencies
- Bluetooth
- Broadcast television systems
- Channel 37
- Digital Audio Broadcasting and its regional implementations
- Digital terrestrial television
- Knife-edge effect
- L-band
- North American broadcast and cable television frequencies
- Television channel frequencies
- Terrestrial television
- Thing (listening device)
- UHF CB
- Very high frequency
- Wi-Fi
References [link]
- ^ https://www.broadcasting-history.ca/stations/radio/Digital_Audio_Broadcasting.html
- ^ Going once, twice, the 700MHz spectrum is sold, NY Times, Mar 18 2008
- ^ https://www.raytheon.com/capabilities/rtnwcm/groups/ncs/documents/content/rtn_ncs_products_arc164_pdf.pdf
External links [link]
- U.S. cable television channel frequencies
- TVTower.com – Commercial Television Frequencies
- Tomislav Stimac, "Definition of frequency bands (VLF, ELF... etc.)". IK1QFK Home Page (vlf.it).
|
|||||||||||||||||
|
|||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||
https://wn.com/Ultra_high_frequency
UHF (song)
"UHF" is an original song by "Weird Al" Yankovic in the key of E major and based on several different riffs. It is the theme song from the film UHF. It is a style parody of themes that are played to advertise television stations. The video parodies other artists and music videos popular during the 1980s, including Guns N' Roses, George Michael, Robert Palmer, Prince, Talking Heads, Peter Gabriel, ZZ Top, Billy Idol, The Beatles, INXS and Randy Newman.
Track listing
7" single
The following tracks are on the 7" single:
The promo single only contains "UHF".
CD single
The following tracks are on the CD single:
The promo single only contains "UHF".
Music video
The "UHF" music video features pastiches of several other music videos, intermixed with clips from the film. The videos parodied in the "UHF" video are:
UHF (Portuguese band)
UHF is a Portuguese rock band formed in the late 1970s in Almada by António Manuel Ribeiro (vocals, guitar and keyboard), Renato Gomes (guitar), Carlos Peres (bass) and Zé Carvalho (drums).
They were the driving force behind the Portuguese rock boom of the early 1980s. At this time very few rock bands had success singing in Portuguese.
UHF already had released their first single, "Jorge morreu" ("George died"), about a death by Overdose, when Rui Veloso, considered by many people as "the father of Portuguese rock", released his monumental first album Ar de rock ("Looks like Rock", a pun on "Hard rock", which is how it sounds in Portuguese). After Veloso's success, a second single, "Cavalos de corrida" ("Racing horses"), was released, followed by three very successful albums in Portugal: À flor da pele, Estou de passagem, and Persona non grata. The group has celebrated 35 years of existence in 2014, with the only member from the original formation being António Manuel Ribeiro, the leader and frontman of the band, and considered to be one of the best rock poets in the history of Portuguese Rock.
Tua
Tua may refer to:
See also
TUA
TUA may stand for:
See also
Cama
Cama is the Spanish/Portuguese word for "bed". It may refer to:
cama is the Fijian term for an ama, or outrigger float, on watercraft.
CAMA is an abbreviation for:
See also
References
Cama, Switzerland
Cama is a municipality in the district of Moesa in the Swiss canton of Graubünden.
History
Cama is first mentioned in 1219 as Camma.
Between 1907 and 1978, Mesocco was linked to Bellinzona and the Gotthard railway to the south, and Mesocco to the north, by the Bellinzona–Mesocco railway. The section between Cama and Castione-Arbedo station, on the Gotthard line, remained open for freight until 2003, and is now operated as a tourist railway.
Geography
Cama has an area, as of 2006, of 15.1 km2 (5.8 sq mi). Of this area, 4.2% is used for agricultural purposes, while 60.1% is forested. Of the rest of the land, 2.7% is settled (buildings or roads) and the remainder (33.1%) is non-productive (rivers, glaciers or mountains).
The municipality is located in the Moesa district in the Roveredo sub-district, along both banks of the Moesa river. It consists of the village of Cama and the sections of Al Pont and Norantola.
Lago di Cama is located in the municipality.
Demographics
Cama has a population (as of 31 December 2014) of 573.As of 2008, 13.6% of the population was made up of foreign nationals. Over the last 10 years the population has grown at a rate of 3%.
