Ultra high frequency

Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (one decimeter). Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF (very high frequency) or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, and numerous other applications.

The IEEE defines the UHF radar band as frequencies between 300 MHz and 1 GHz.[1] Two other IEEE radar bands overlap the ITU UHF band: the L band between 1 and 2 GHz and the S band between 2 and 4 GHz.

UHF TV Antenna 001
UHF television antenna on a residence. This type of antenna, called a Yagi-Uda antenna, is widely used at UHF frequencies.
Reflective array, bow tie, grid, or panel UHF television antenna,
Another antenna type common at UHF; a reflective array TV antenna consisting of two high-bandwidth "bow tie" dipoles in front of a flat reflector screen. The antenna is oriented so as to receive vertically-polarized radio waves, while most UHF TV stations transmit horizontally polarized waves.
Ultra high frequency
Ultra high frequency (ITU)
Frequency range
300 MHz to 3 GHz
Wavelength range
1 m to 1 dm
Related bands
Ultra high frequency (IEEE)
Frequency range
300 MHz to 1 GHz
Wavelength range
1 m to 3 dm
Related bands

Propagation characteristics

Binatone MR 200 radio 1
Walkie talkies which operate on the 446 MHz PMR (Professional Mobile Radio) band. The 67 cm wavelength permits them to use very short "Rubber Ducky" antennas.

Radio waves in the UHF band travel almost entirely by line-of-sight propagation (LOS) and ground reflection; unlike in the HF band there is little to no reflection from the ionosphere (skywave propagation), or ground wave.[2] UHF radio waves are blocked by hills and cannot travel far beyond the horizon, but can penetrate foliage and buildings for indoor reception. Since the wavelengths of UHF waves are comparable to the size of buildings, trees, vehicles and other common objects, reflection and diffraction from these objects can cause fading due to multipath propagation, especially in built-up urban areas. Atmospheric moisture reduces, or attenuates, the strength of UHF signals over long distances, and the attenuation increases with frequency. UHF TV signals are generally more degraded by moisture than lower bands, such as VHF TV signals.

Since UHF transmission is limited by the visual horizon to 30–40 miles (48–64 km) and often to shorter distances by local terrain, it allows the same frequency channels to be reused by other users in neighboring geographic areas (frequency reuse). Public safety, business communications and personal radio services such as GMRS, PMR446, and UHF CB are often found on UHF frequencies as well as IEEE 802.11 wireless LANs ("Wi-Fi"). The widely adopted GSM and UMTS cellular networks use UHF cellular frequencies. Radio repeaters are used to retransmit UHF signals when a distance greater than the line of sight is required.

Occasionally when conditions are right, UHF radio waves can travel long distances by tropospheric ducting as the atmosphere warms and cools throughout the day.

Antennas

Corner reflector TV antenna
Corner reflector UHF-TV antenna from 1950s

The length of an antenna is related to the length of the radio waves used. Due to the short wavelengths, UHF antennas are conveniently stubby and short; at UHF frequencies a quarter-wave monopole, the most common omnidirectional antenna is between 2.5 and 25 cm long. UHF wavelengths are short enough that efficient transmitting antennas are small enough to mount on handheld and mobile devices, so these frequencies are used for two way land mobile radio systems, such as walkie-talkies, two way radios in vehicles, and for portable wireless devices; cordless phones and cell phones. Omnidirectional UHF antennas used on mobile devices are usually short whips, sleeve dipoles, rubber ducky antennas or the planar inverted F antenna (PIFA) used in cellphones. Higher gain omnidirectional UHF antennas can be made of collinear arrays of dipoles and are used for mobile base stations and cellular base station antennas.

The short wavelengths also allow high gain antennas to be conveniently small. High gain antennas for point-to-point communication links and UHF television reception are usually Yagi, log periodic, corner reflectors, or reflective array antennas. At the top end of the band slot antennas and parabolic dishes become practical. For satellite communication, helical, and turnstile antennas are used since satellites typically employ circular polarization which is not sensitive to the relative orientation of the transmitting and receiving antennas. For television broadcasting specialized vertical radiators that are mostly modifications of the slot antenna or reflective array antenna are used: the slotted cylinder, zig-zag, and panel antennas.

Applications

UHF television broadcasting fulfilled 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.

UHF spectrum is used worldwide 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.

Major telecommunications providers have deployed voice and data cellular networks in UHF/VHF range. This allows mobile phones and mobile computing devices to be connected to the public switched telephone network and public Internet.

UHF radars are said to be effective at tracking stealth fighters, if not stealth bombers.[3]

Examples of UHF frequency allocations

Australia

  • UHF citizens band(Land mobile service): 476–477 MHz
  • Television broadcasting uses UHF channels between 503 and 694 MHz
  • Fixed point-to-point Link 450.4875 - 451.5125 MHz
  • Land mobile service 457.50625 - 459.9875 MHz
  • Mobile satellite service: 406.0000 - 406.1000 MHz
  • Segment and Service examples: Land mobile for private, Australian, State and Territory Government, Rail industry and Mobile-Satellite [4]

Canada

  • 430–450 MHz: Amateur radio (ham – 70 cm band)
  • 470–806 MHz: Terrestrial television (with select channels in the 700 MHz band left vacant)
  • 1452–1492 MHz: Digital Audio Broadcasting (L band)[5]
  • Many other frequency assignments for Canada and Mexico are similar to their US counterparts

United Kingdom

  • 380–399.9 MHz: Terrestrial Trunked Radio (TETRA) service for emergency use
  • 430–440 MHz: Amateur radio (ham – 70 cm band)
  • 446.0–446.2 MHz : European unlicensed PMR service => PMR446
  • 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: Previously used for analogue TV channels 21–69 (until 2012).
    • Currently channels 21–35, 37 and 39–60 are used for Freeview digital TV.[6] Channel 36 is used for radar; channel 38 was used for radio astronomy but has been cleared to allow PMSE users access on a licensed, shared basis.
    • 791–862 MHz,[7] i.e. channels 61–69 inclusive were previously used for licensed and shared wireless microphones (channel 69 only), has since been allocated to 4G cellular communications.
  • 863 - 865 MHz: Used for licence-exempt wireless systems.
  • 863–870 MHz: Short range devices, LPWAN IoT devices such as NarrowBand-IoT.
  • 870–960 MHz: Cellular communications (GSM900 - Vodafone and O2 only) including GSM-R and future TETRA
  • 1240–1325 MHz: Amateur radio (ham – 23 cm band)
  • 1710–1880 MHz: 2G Cellular communications (GSM1800)
  • 1880–1900 MHz: DECT cordless telephone
  • 1900–1980 MHz: 3G cellular communications - mobile phone uplink
  • 2110–2170 MHz: 3G cellular communications - base station downlink
  • 2310–2450 MHz: Amateur radio (ham – 13 cm band)

United States

UHF channels are used for digital television broadcasting on both over the air channels and cable television channels. Since 1962, UHF channel tuners (at the time, channels 14-83) have been required in television receivers by the All-Channel Receiver Act. However, because of their more limited range, and because few sets could receive them until older sets were replaced, UHF channels were less desirable to broadcasters than VHF channels (and licenses sold for lower prices).

A complete list of US Television Frequency allocations can be found at North American Television Frequencies.

There is a considerable amount of lawful unlicensed activity (cordless phones, wireless networking) clustered around 900 MHz and 2.4 GHz, regulated under Title 47 CFR Part 15. These ISM bands – frequencies with a higher unlicensed power permitted for use originally by Industrial, Scientific, Medical apparatus – are now 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, adjacent to the frequencies allocated for Bluetooth network devices.

The spectrum from 806 MHz to 890 MHz (UHF channels 70–83) was taken away from TV broadcast services in 1983, primarily for analog 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 removed from TV broadcasting, making it available for other uses. Channel 55, for instance, was sold to Qualcomm for their MediaFLO service, which was later sold to AT&T, and discontinued in 2011. 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.[8]

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. The FCC did not include a wholesale condition, which would have required the owner of the band to resell bandwidth to third parties who could then service the end user. Google argued that the wholesale requirement would have stimulated internet competition. As of 2007, 96% of the country's broadband access was controlled by DSL and cable providers. A wholesale condition could have meant a third option for internet service.[9]

  • 225–420 MHz: Government use, including meteorology, military aviation, and federal two-way use[10]
  • 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: Low-band TV channels 14–20 (shared with public safety land mobile 2-way radio in 12 major metropolitan areas scheduled to relocate to 700 MHz band by 2023[11])
  • 512–608 MHz: Medium-band TV channels 21–36
  • 608–614 MHz: Channel 37 used for radio astronomy and wireless medical telemetry[12]
  • 614–698 MHz: Mobile broadband shared with TV channels 38–51 auctioned in April 2017. TV stations will relocate by 2020.
    • 617–652 MHz: Mobile broadband service downlink
    • 652–663 MHz: Wireless microphones (higher priority) and unlicensed devices (lower priority)
    • 663–698 MHz: Mobile broadband service uplink
  • 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 high-band UHF TV channels 52–69)
  • 806–816 MHz: Public safety and commercial 2-way (formerly TV channels 70–72)
  • 817–824 MHz: ESMR band for wideband mobile services (mobile phone) (formerly public safety and commercial 2-way)
  • 824–849 MHz: Cellular A & B franchises, terminal (mobile phone) (formerly TV channels 73–77)
  • 849–851 MHz: Commercial aviation air-ground systems (Gogo)
  • 851–861 MHz: Public safety and commercial 2-way (formerly TV channels 77–80)
  • 862–869 MHz: ESMR band for wideband mobile services (base station) (formerly public safety and commercial 2-way)
  • 869–894 MHz: Cellular A & B franchises, base station (formerly TV channels 80–83)
  • 894–896 MHz: Commercial aviation air-ground systems (Gogo)
  • 896–901 MHz: Commercial 2-way radio
  • 901–902 MHz: Narrowband PCS: commercial narrowband mobile services
  • 902–928 MHz: ISM band, amateur radio (33 cm band), cordless phones and stereo, radio-frequency identification, datalinks
  • 928–929 MHz: SCADA, alarm monitoring, meter reading systems and other narrowband services for a company internal use
  • 929–930 MHz: Pagers
  • 930–931 MHz: Narrowband PCS: commercial narrowband mobile services
  • 931–932 MHz: Pagers
  • 932–935 MHz: Fixed microwave services: distribution of video, audio and other data
  • 935–940 MHz: Commercial 2-way radio
  • 940–941 MHz: Narrowband PCS: commercial narrowband mobile services
  • 941–960 MHz: Mixed studio-transmitter fixed links, SCADA, other.
  • 960–1215 MHz: Aeronautical radionavigation
  • 1240–1300 MHz: Amateur radio (23 cm band)
  • 1300–1350 MHz: Long range radar systems
  • 1350–1390 MHz: Military air traffic control and mobile telemetry systems at test ranges
  • 1390–1395 MHz: Proposed wireless medical telemetry service. TerreStar failed to provide service by the required deadline[13].
  • 1395–1400 MHz: Wireless medical telemetry service
  • 1400–1427 MHz: Earth exploration, radio astronomy, and space research
  • 1427–1432 MHz: Wireless medical telemetry service
  • 1432–1435 MHz: Proposed wireless medical telemetry service. TerreStar failed to provide service by the required deadline[13].
  • 1435–1525 MHz: Military use mostly for aeronautical mobile telemetry (therefore not available for Digital Audio Broadcasting, unlike Canada/Europe)
  • 1525–1559 MHz: Skyterra downlink (Ligado is seeking FCC permission for terrestrial use[14])
    • 1526–1536 MHz: proposed Ligado downlink
    • 1536–1559 MHz: proposed guard band
  • 1559–1610 MHz: Radio Navigation Satellite Services (RNSS) Upper L-band
    • 1563–1587 MHz: GPS L1 band
    • 1593–1610 MHz: GLONASS G1 band
    • 1559–1591 MHz: Galileo E1 band (overlapping with GPS L1[15])
  • 1610–1660.5 MHz: Mobile Satellite Service
    • 1610–1618: Globalstar uplink
    • 1618–1626.5 MHz: Iridium uplink and downlink[14]
    • 1626.5–1660.5 MHz: Skyterra uplink (Ligado is seeking FCC permission for terrestrial use[14])
      • 1627.5–1637.5 MHz: proposed Ligado uplink 1
      • 1646.5–1656.5 MHz: proposed Ligado uplink 2
  • 1660.5–1668.4 MHz: Radio astronomy observations. Transmitting is not permitted.
  • 1668.4–1670 MHz: Radio astronomy observations. Weather balloons may utilize the spectrum after an advance notice.
  • 1670–1675 MHz: Geostationary Operational Environmental Satellite transmissions to three earth stations in Wallops Island, VA; Greenbelt, MD and Fairbanks, AK. Nationwide broadband service license in this range is held by a subsidiary of Crown Castle International Corp. who is trying to provide service in cooperation with Ligado Networks.[16]
  • 1675–1695 MHz: Meteorological federal users
  • 1695–1780 MHz: AWS mobile phone uplink (UL) operating band
    • 1695–1755 MHz: AWS-3 blocks A1 and B1
    • 1710–1755 MHz: AWS-1 blocks A, B, C, D, E, F
    • 1755–1780 MHz: AWS-3 blocks G, H, I, J (various federal agencies transitioning by 2025[17])
  • 1780–1850 MHz: exclusive federal use (Air Force satellite communications, Army's cellular-like communication system, other agencies)
  • 1850–1920 MHz: PCS mobile phone—order is A, D, B, E, F, C, G, H blocks. A, B, C = 15 MHz; D, E, F, G, H = 5 MHz
  • 1920–1930 MHz: DECT cordless telephone
  • 1930–2000 MHz: PCS base stations—order is A, D, B, E, F, C, G, H blocks. A, B, C = 15 MHz; D, E, F, G, H = 5 MHz
  • 2000–2020 MHz: lower AWS-4 downlink (mobile broadband)
  • 2020–2110 MHz: Cable Antenna Relay service, Local Television Transmission service, TV Broadcast Auxiliary service, Earth Exploration Satellite service
  • 2110–2200 MHz: AWS mobile broadband downlink
    • 2110–2155 MHz: AWS-1 blocks A, B, C, D, E, F
    • 2155–2180 MHz: AWS-3 blocks G, H, I, J
    • 2180–2200 MHz: upper AWS-4
  • 2200–2290 MHz: NASA satellite tracking, telemetry and control (space-to-Earth, space-to-space)
  • 2290–2300 MHz: NASA Deep Space Network
  • 2300–2305 MHz: Amateur radio (13 cm band, lower segment)
  • 2305–2315 MHz: WCS mobile broadband service uplink blocks A and B
  • 2315–2320 MHz: WCS block C (AT&T is pursuing smart grid deployment[18])
  • 2320–2345 MHz: Satellite radio (Sirius and XM)
  • 2345–2350 MHz: WCS block D (AT&T is pursuing smart grid deployment[18])
  • 2350–2360 MHz: WCS mobile broadband service downlink blocks A and B
  • 2360–2390 MHz: Aircraft landing and safety systems
  • 2390–2395 MHz: Aircraft landing and safety systems (secondary deployment in a dozen of airports), amateur radio otherwise
  • 2395–2400 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 (strictly for spread spectrum use), microwave ovens, ZigBee
  • 2483.5–2495 MHz: Globalstar downlink and Terrestrial Low Power Service suitable for TD-LTE small cells[19]
  • 2495–2690 MHz: Educational Broadcast and Broadband Radio Services[20]
  • 2690–2700 MHz: Receive-only range for radio astronomy and space research

See also

References

  1. ^ "IEEE 521-2002 - IEEE Standard Letter Designations for Radar-Frequency Bands". Standards.ieee.org. Retrieved 17 December 2017.
  2. ^ Seybold, John S. (2005). Introduction to RF Propagation. John Wiley and Sons. pp. 55–58. ISBN 0471743682.
  3. ^ MINNICK, WENDELL (22 November 2014). "China's Anti-Stealth Radar Comes to Fruition". Defensenews.com. Gannett. Retrieved 25 November 2014.
  4. ^ https://www.acma.gov.au/-/media/Spectrum-Engineering/Information/pdf/Radiocommunications-Assignment-and-Licensing-Instruction-RALI-MS22-400-MHz-Plan.pdf
  5. ^ "Digital Audio Broadcasting (DAB) - History of Canadian Broadcasting". Broadcasting-history.ca. Retrieved 15 October 2017.
  6. ^ UK Digital Terrestrial Television Transmitter Frequency and Site Data, Ofcom, retrieved 16 October 2013
  7. ^ "800 MHz & 2.6 GHz Combined Award". The Office of Communications. Retrieved 2014-11-21.
  8. ^ Hansell, Saul. "Going Once…Going Twice…The 700 Mhz Spectrum is Sold". Bits.blos.nytimes.com. Retrieved 15 October 2017.
  9. ^ FCC opens up US wireless spectrum, The Register, 1 August 2007, Cade Metz
  10. ^ [1]
  11. ^ "T-Band Report" (PDF). Npstc.org. Retrieved 17 December 2017.
  12. ^ "Wireless Medical Telemetry Service (WMTS)". Fcc.gov. Retrieved 17 December 2017.
  13. ^ a b "TerreStar Corporation Request for Temporary Waiver of Substantial Service Requirements for 1.4 GHz Licenses" (PDF). the FCC. 2017-10-10. Retrieved 2017-10-11.
  14. ^ a b c "Ligado Ex Parte re Iridium Analysis (PUBLIC 11-2-2016)" (PDF). Ecfsapi.fcc.gov. Retrieved 17 December 2017.
  15. ^ "Galileo Signal Plan". Navipedia.net. Retrieved 17 December 2017.
  16. ^ "REQUEST FOR WAIVER AND PUBLIC INTEREST STATEMENT". FCC. 2016-06-04. Retrieved 2018-04-02.
  17. ^ "AWS-3 Transition". Ntia.doc.gov. Retrieved 17 December 2017.
  18. ^ a b "AT&T Mobility Petition for Limited Waiver of Interim Performance Requirement for 2.3 GHz WCS C and D Block Licenses" (PDF). Ecfsapi.fcc.gov. Retrieved 17 December 2017.
  19. ^ "Globalstar Overview" (PDF). Globalstar.com. Retrieved 17 December 2017.
  20. ^ "Broadband Radio Service & Education Broadband Service". The FCC. Retrieved 2018-06-05.

External links

Adcock antenna

The Adcock antenna is an antenna array consisting of four equidistant vertical elements which can be used to transmit or receive directional radio waves.

The Adcock array was invented and patented by British engineer Frank Adcock in 1919 as British Patent No. 130,490, and has been used for a variety of applications, both civilian and military, ever since. Although originally conceived for receiving low frequency (LF) waves, it has also been used for transmitting, and has since been adapted for use at much higher frequencies, up to ultra high frequency (UHF).In the early 1930s, the Adcock antenna (transmitting in the LF/MF bands) became a key feature of the newly created radio navigation system for aviation. The low frequency radio range (LFR) network, which consisted of hundreds of Adcock antenna arrays, defined the airways used by aircraft for instrument flying. The LFR remained as the main aerial navigation technology until it was replaced by the VOR system in the 1950s and 1960s.

The Adcock antenna array has been widely used commercially, and implemented in vertical antenna heights ranging from over 130 feet (40 meters) in the LFR network, to as small as 5 inches (13 cm) in tactical direction finding applications (receiving in the UHF band).

Band IV

Band IV is the name of a radio frequency range within the ultra high frequency part of the electromagnetic spectrum.Sources differ on the exact frequency range of the band. For example, the Swiss Federal Office of Communications, the Broadcast engineer's reference book and Ericsson India Ltd all define the range of Band IV from 470 to 582 MHz. An EICTA paper defines the range as 474 to 602 MHz, whilst the BBC define the range as 470 to 614 MHz. Band IV is primarily used for analogue and digital (DVB-T, ATSC and ISDB) television broadcasting, as well as services intended for mobile devices such as DVB-H.

Band V

Band V (meaning Band 5) is the name of a radio frequency range within the ultra high frequency part of the electromagnetic spectrum. It is not to be confused with the V band in the extremely high frequency part of the spectrum.

Sources differ on the exact frequency range of UHF Band V. For example, the Broadcast engineer's reference book and the BBC define the range as 614 to 854 MHz. The IPTV India Forum define the range as 582 to 806 MHz and the DVB Worldwide website refers to the range as 585 to 806 MHz. Band V is primarily used for analogue and digital (DVB-T & ATSC) television broadcasting, as well as radio microphones and services intended for mobile devices such as DVB-H. With the close-down of analog television services most countries have auctioned off frequencies from 694 MHz and up to 4G cellular network providers.

Broadband over power lines

Broadband over power lines (BPL) is a method of power line communication (PLC) that allows relatively high-speed digital data transmission over the public electric power distribution wiring. BPL uses higher frequencies, a wider frequency range and different technologies from other forms of power-line communications to provide high-rate communication over longer distances. BPL uses frequencies which are part of the radio spectrum allocated to over-the-air communication services therefore the prevention of interference to, and from, these services is a very important factor in designing BPL systems.

Cellular frequencies

Cellular frequencies are the sets of frequency ranges within the ultra high frequency band that have been assigned for cellular-compatible mobile devices, such as mobile phones, to connect to cellular networks. Most mobile networks worldwide use portions of the radio frequency spectrum, allocated to the mobile service, for the transmission and reception of their signals. The particular bands may also be shared with other radiocommunication services, e.g. broadcasting service, and fixed service operation.

Don-2N radar

The Don-2N radar (Russian: Дон-2Н, NATO: Pill Box) is a large missile defense and early warning passive electronically scanned array radar outside Moscow, and a key part of the Russian A-135 anti-ballistic missile system designed for the defense of the capital against ballistic missiles. Located in the Pushkino district of Moscow it is a quadrangular frustum 33 metres (108 ft) tall with sides 130 metres (427 ft) long at the bottom, and 90 metres (295 ft) long at the top. Each of its four faces has an 18 metres (59 ft) diameter Ultra high frequency band radar giving 360 degree coverage. The system is run by an Elbrus-2 (Russian: Эльбрус-2) supercomputer.It has a range of 3,700 km for targets the size of a typical ICBM warhead.Under the 1972 Anti-Ballistic Missile Treaty both the United States and the Soviet Union had to designate one area to protect from missile attack. The USA chose North Dakota and the Soviet Union chose Moscow. The Don-2N radar is designed to be the control centre of the system and can operate autonomously if connection is lost to its command and control centre.

The 1998 SIOP targeted this radar facility with 69 consecutive nuclear weapons.

Duophonic Records

Duophonic Ultra High Frequency Disks Limited (also known as Duophonic Records or Duophonic Super 45s) is a British independent record label formed by English-French rock band Stereolab in 1991. The label has two imprints: Duophonic Ultra High Frequency Disks for UK Stereolab releases licensed to various labels worldwide, and Duophonic Super 45s for releases of other artists and certain Stereolab UK-only releases. Duophonic's first release was Stereolab's debut EP Super 45 (1991), limited to 880 copies; of these, forty copies had handmade covers that were produced by Martin Pike in his father's garage.

Bands that have released records on Duophonic include Broadcast, the High Llamas, Labradford, Tortoise, Pram, Yo La Tengo, the Notwist, and Apparat Organ Quartet. Daft Punk, one of the most successful electronic bands of the 1990s, released their first songs under the name Darlin' on the 1993 Duophonic compilation Shimmies in Super 8. Duophonic's most successful release is Stereolab's Emperor Tomato Ketchup (1996), which was licensed to Elektra Records outside the UK and has sold over 60,000 copies worldwide.

Duophonic is managed by Martin Pike, and is owned by Tim Gane (34%), Laetitia Sadier (34%), and Pike (32%). Although founded in 1991, the label did not become a limited company until 25 August 1993, when Pike relocated from Horsham, West Sussex, to East Dulwich in the London Borough of Southwark. From there, Pike also runs Associated London Management [2008] Ltd, a company dedicated to the management of bands such as Stereolab, Broadcast, Deerhunter, Atlas Sound, and the High Llamas.

Filter capacitor

Filter capacitors are capacitors used for filtering of undesirable frequencies. They are common in electrical and electronic equipment, and cover a number of applications, such as:

Glitch removal on Direct current (DC) power rails

Radio frequency interference (RFI) removal for signal or power lines entering or leaving equipment

Capacitors used after a voltage regulator to further smooth dc power supplies

Capacitors used in audio, intermediate frequency (IF) or radio frequency (RF) frequency filters (e.g. low pass, high pass, notch, etc.)

Arc suppression, such as across the contact breaker or 'points' in a spark-ignition engineFilter capacitors are not the same as reservoir capacitors, the tasks the two perform are different, albeit related.

John Grist Brainerd

John Grist Brainerd (1904 – February 1, 1988) was an American electrical engineer who served as principal investigator on the project to build ENIAC, the first general-purpose electronic digital computer. Later, he was dean of the Moore School of Electrical Engineering at the University of Pennsylvania.

Brainerd was born in 1904; he earned a bachelor's degree in electrical engineering from the University of Pennsylvania in 1925, and a Ph.D. in 1929. He became an instructor in the Moore school in 1925, and directed the school from 1954 to 1970. In 1970 he retired, as emeritus University Professor.Brainerd's most famous contribution, with J. Presper Eckert, John Mauchly, and others, was the creation of ENIAC, the first general-purpose electronic digital computer. Although Eckert and Mauchly were the chief designers of ENIAC, Brainerd was selected as principal investigator of the ENIAC project, which took place between 1943 and 1946 at the Moore school. He also helped found the graduate program in electrical engineering at Penn, in 1927, and wrote two textbooks, High Frequency Alternating Currents (1931) and Ultra-High Frequency Techniques (1942). After retiring, he became president of the Society for the History of Technology.Brainerd was the recipient of the IEEE Founders Medal in 1975 "for his leadership in electronics in fields encompassing computer technology, high frequency techniques, engineering education, and national and international electrical standardization."

Joint Communications Unit

The Joint Communications Unit (JCU) is a unit of the Joint Special Operations Command charged to standardize and ensure interoperability of the communication procedures and equipment of JSOC and its subordinate units. JCU was activated at Ft. Bragg, NC in 1980, after the failure of Operation Eagle Claw. JCU has earned the reputation of "DoD's Finest Communicators".The JCU prides itself in its ability to conduct operations and exercises on a variety of platforms including, but not limited to ships, aircraft, vehicle and field conditions. The JCU has positions for active duty Army, Air Force, Navy, Marine Corps, and DoD civilian personnel in a variety of communications, automation, electronics maintenance and logistic specialties. The JCU is an "Airborne" unit; however, attendance to the United States Army Airborne School is voluntary. Because of the JCU's deployment status, unit personnel receive a wide range of training, including: ultra high frequency and super high frequency satellite systems, local area networks, wide area networks, servers, active directories, networking, voice over IP, videotelephony, video distribution, fiber system installation, and advanced tactical communication scenarios on various air, land, and sea platforms.

Mobile User Objective System

The Mobile User Objective System is a narrowband military communications satellite system that supports a worldwide, multi-Service population of users in the ultra high frequency band. The system provides increased communications capabilities to newer, smaller terminals while still supporting interoperability with legacy terminals. MUOS is designed to support users who require greater mobility, higher bit rates and improved operational availability.

Radio noise

In radio reception, noise is unwanted random electrical signals always present in a radio receiver in addition to the desired radio signal. Radio noise is a combination of natural electromagnetic atmospheric noise ("spherics", static) created by electrical processes in the atmosphere like lightning, manmade radio frequency interference (RFI) from other electrical devices picked up by the receiver's antenna, and thermal noise present in the receiver input circuits, caused by the random thermal motion of molecules. The level of noise determines the maximum sensitivity and reception range of a radio receiver; if no noise were picked up with radio signals, even weak transmissions could be received at virtually any distance by making a radio receiver that was sensitive enough. With noise present, if a radio source is so weak and far away that the radio signal in the receiver has a lower amplitude than the average noise, the noise will drown out the signal.

The limiting noise source in a receiver depends on the frequency range in use. At frequencies below about 40 MHz, particularly in the mediumwave and longwave bands and below, atmospheric noise and nearby radio frequency interference from electrical switches, motors, vehicle ignition circuits, computers, and other man-made sources tends to be above the thermal noise floor in the receiver's circuits. These noises are often referred to as static. Conversely, at very high frequency and ultra high frequency and above, these sources are often lower, and thermal noise is usually the limiting factor. In the most sensitive receivers at these frequencies, radio telescopes and satellite communication antennas, thermal noise is reduced by cooling the RF front end of the receiver to cryogenic temperatures. Cosmic background noise is experienced at frequencies above about 15 MHz when highly directional antennas are pointed toward the sun or to certain other regions of the sky such as the center of the Milky Way Galaxy.

Electromagnetic noise can interfere with electronic equipment in general, causing malfunction, and in recent years standards have been laid down for the levels of electromagnetic radiation that electronic equipment is permitted to radiate. These standards are aimed at ensuring what is referred to as electromagnetic compatibility (EMC).

Scepter Records

Scepter Records is an American record company founded in 1959 by Florence Greenberg.

Truth Channel

Truth Channel, formerly known as Ang Dating Daan Television (ADDTV) is a Philippine religious television network.

It is the flagship television network of the Members Church of God International (MCGI), together with UNTV News and Rescue, the network's carrier on free-to-air digital terrestrial television (DTT). It broadcasts 24 hours a day on Ultra High Frequency (UHF) Channel 38 (617.143 MHz) in Metro and Mega Manila, Rizal, Bulacan, Pampanga, Laguna, Cavite and some parts of Tarlac.

Its studios in the Philippines are located at the UNTV Building, 907 Brgy. Philam, EDSA Quezon City and at the ADD Convention Center, Brgy. Sampaloc, MacArthur Highway Apalit, Pampanga.

It also has a broadcast facility in South America, a garage transformed into a makeshift studio in Florianópolis, Sta. Catarina, Brazil, shared with MCGI's own international TV channels TV Verdade, TV La Verdad and The Truth Channel.Its digital transmitter is located at Emerald Hills, Sumulong Highway in Antipolo, Rizal. The 16-storey UNTV Broadcast Center along EDSA Philam is currently under construction to serve as its new headquarters by 2018.

Truth Channel is known for its broadcast of Itanong mo kay Soriano, a talk show in Bible Exposition format popularized by Ang Dating Daan (ADD), the longest-running religious program in the Philippines, hosted by international radio and television evangelist Eliseo Soriano, the Overall Servant to the Members Church of God International (MCGI) together with broadcast journalist and UNTV CEO Daniel Razon.

The segment has spontaneous question and answer format where live audience ask questions to the host. The religious program airs in four languages namely Filipino, English, Portuguese and Spanish with English subtitles.

UHF Television Yamanashi

Ultra high frequency Television Yamanashi, Inc. (株式会社テレビ山梨, Kabushiki-gaisha TV Yamanashi), also known as UTY, is a Japanese broadcast network affiliated with the JNN. Its headquarters are located in Kōfu, Yamanashi.

UHF connector

The UHF connector is a dated name for a threaded RF connector.

The connector design was invented in the 1930s for use in the radio industry, and is a shielded form of the "banana plug". It is a widely-used standard connector for HF transmission lines on full-sized radio equipment, with BNC connectors predominating for smaller, hand-held equipment.The name "UHF" is a source of legitimate confusion, since the name of the connectors did not change when the frequency ranges were renamed. The design was named during an era when "UHF" meant frequencies over 30 MHz. Today Ultra high frequency (UHF) instead refers to frequencies between 300 MHz and 3 GHz and the range of frequencies formerly known as UHF is now called "VHF". Further adding to the confusion, the so-called "UHF" connectors are only well suited for the lower-VHF range and lower; they perform poorly for the higher modern UHF region. A more appropriate name would be "HF" connectors.

There is no active specification or standard governing the mechanical and electrical characteristics of the so-called "UHF" connector system making it effectively a deprecated design..

Ultra High Frequency (band)

Ultra High Frequency was a Long Island, New York based alternative rock band.

WTAP-TV

WTAP-TV is an NBC-affiliated television station licensed to Parkersburg, West Virginia, United States and serving the Mid-Ohio Valley. It broadcasts a high definition digital signal on ultra high frequency (UHF) channel 49 (or virtual channel 15.1 via PSIP) from a transmitter in Independence Township, Ohio. The station can also be seen on Suddenlink channel 4 and CAS Cable channel 3. Owned by Gray Television, WTAP is sister to two low-powered stations: Fox affiliate WOVA-LD (channel 22) and CBS affiliate WIYE-LD (channel 47). The three stations share studios on Market Street (official address is One Television Plaza) in downtown Parkersburg.

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