Natchez is the county seat and only city of Adams County, United States. Natchez has a total population of 15,792. Located on the Mississippi River across from Vidalia in Concordia Parish, Natchez was a prominent city in the antebellum years, a center of cotton planters and Mississippi River trade. Natchez is some 90 miles southwest of Jackson, the capital of Mississippi, located near the center of the state, it is 85 miles north of Baton Rouge, located on the lower Mississippi River. Natchez is the 25th-largest city in the state; the city was named for the Natchez tribe of Native Americans, who with their ancestors, inhabited much of the area from the 8th century AD through the French colonial period. Established by French colonists in 1716, Natchez is one of the oldest and most important European settlements in the lower Mississippi River Valley. After the French lost the French and Indian War, they ceded Natchez and near territory to Spain in the Treaty of Paris of 1763.. After the United States acquired this area from the British after the American Revolutionary War, the city served as the capital of the American Mississippi Territory and of the state of Mississippi.
It predates Jackson by more than a century. The strategic location of Natchez, on a bluff overlooking the Mississippi River, ensured that it would be a pivotal center of trade and the interchange of ethnic Native American and African cultures in the region. In U. S. history, Natchez is recognized for its role in the development of the Old Southwest during the first half of the nineteenth century. It was the southern terminus of the historic Natchez Trace, with the northern terminus being Nashville, Tennessee. After unloading their cargoes in Natchez or New Orleans, many pilots and crew of flatboats and keelboats traveled by the Trace overland to their homes in the Ohio River Valley; the Natchez Trace played an important role during the War of 1812. Today the modern Natchez Trace Parkway, which commemorates this route, still has its southern terminus in Natchez. In the middle of the nineteenth century, the city attracted wealthy Southern planters as residents, who built mansions to fit their ambitions.
Their plantations were vast tracts of land in the surrounding lowlands along the river fronts of Mississippi and Louisiana, where they grew large commodity crops of cotton and sugarcane using slave labor. Natchez became the principal port from which these crops were exported, both upriver to Northern cities and downriver to New Orleans, where much of the cargo was exported to Europe. Many of the mansions built by planters before 1860 survive and form a major part of the city's architecture and identity. Agriculture remained the primary economic base for the region until well into the twentieth century. During the American Civil War Natchez was surrendered by Confederate forces without a fight in September, 1862. Following the Union victory at the Battle of Vicksburg in July, 1863, many refugees, including former slaves, freed by the Emancipation Proclamation, began moving into Natchez and the surrounding countryside; the Union Army officers claimed to be unable to provide for the refugees. The Army planned to address the situation with a mixture of paid labor for freed slaves on government leased plantations, the enlistment of able bodied males who were willing to fight in the Union Army and the establishment of refugee camps where former slaves could be provided with education.
However, as the war continued, the plan was never implemented and the leased plantations were poorly managed and raided by Confederate troops who controlled the surrounding territory. Hundreds of people living in Natchez, including many former slaves and refugees, died of hunger, disease or were killed in the fighting during this period. After the American Civil War, the city's economy revived due to Natchez having been spared the destruction visited upon many other parts of the South; the vitality of the city and region was captured most in the 80 years or so following the war by the photographers Henry C. Norman and his son Earl; the output of the Norman Studio between 1870 and 1950 documents this period in Natchez's development vividly. During the twentieth century, the city's economy experienced a downturn, first due to the replacement of steamboat traffic on the Mississippi River by railroads in the early 1900s, some of which bypassed the river cities and drew away their commerce. In the 20th century, many local industries closed in a restructuring that reduced the number of jobs in the area.
Despite its status as a popular destination for heritage tourism because of well-preserved antebellum architecture, Natchez has had a general decline in population since 1960. It remains the principal city of the MS -- LA Micropolitan Statistical Area. Natchez is located at 31°33'16" latitude, 91°23'15" longitude. According to the United States Census Bureau, the city has a total area of 13.9 square miles, of which 13.2 square
The National Broadcasting Company is an American English-language commercial terrestrial television network, a flagship property of NBCUniversal, a subsidiary of Comcast. The network is headquartered at 30 Rockefeller Plaza in New York City, with additional major offices near Los Angeles and Philadelphia; the network is one of the Big Three television networks. NBC is sometimes referred to as the "Peacock Network", in reference to its stylized peacock logo, introduced in 1956 to promote the company's innovations in early color broadcasting, it became the network's official emblem in 1979. Founded in 1926 by the Radio Corporation of America, NBC is the oldest major broadcast network in the United States. At that time the parent company of RCA was General Electric. In 1930, GE was forced to sell the companies as a result of antitrust charges. In 1986, control of NBC passed back to General Electric through its $6.4 billion purchase of RCA. Following the acquisition by GE, Bob Wright served as chief executive officer of NBC, remaining in that position until his retirement in 2007, when he was succeeded by Jeff Zucker.
In 2003, French media company Vivendi merged its entertainment assets with GE, forming NBC Universal. Comcast purchased a controlling interest in the company in 2011, acquired General Electric's remaining stake in 2013. Following the Comcast merger, Zucker left NBCUniversal and was replaced as CEO by Comcast executive Steve Burke. NBC has thirteen owned-and-operated stations and nearly 200 affiliates throughout the United States and its territories, some of which are available in Canada and/or Mexico via pay-television providers or in border areas over-the-air. During a period of early broadcast business consolidation, radio manufacturer Radio Corporation of America acquired New York City radio station WEAF from American Telephone & Telegraph. Westinghouse, a shareholder in RCA, had a competing outlet in Newark, New Jersey pioneer station WJZ, which served as the flagship for a loosely structured network; this station was transferred from Westinghouse to RCA in 1923, moved to New York City. WEAF acted as a laboratory for AT&T's manufacturing and supply outlet Western Electric, whose products included transmitters and antennas.
The Bell System, AT&T's telephone utility, was developing technologies to transmit voice- and music-grade audio over short and long distances, using both wireless and wired methods. The 1922 creation of WEAF offered a research-and-development center for those activities. WEAF maintained a regular schedule of radio programs, including some of the first commercially sponsored programs, was an immediate success. In an early example of "chain" or "networking" broadcasting, the station linked with Outlet Company-owned WJAR in Providence, Rhode Island. C. WCAP. New parent RCA saw an advantage in sharing programming, after getting a license for radio station WRC in Washington, D. C. in 1923, attempted to transmit audio between cities via low-quality telegraph lines. AT&T refused outside companies access to its high-quality phone lines; the early effort fared poorly, since the uninsulated telegraph lines were susceptible to atmospheric and other electrical interference. In 1925, AT&T decided that WEAF and its embryonic network were incompatible with the company's primary goal of providing a telephone service.
AT&T offered to sell the station to RCA in a deal that included the right to lease AT&T's phone lines for network transmission. RCA spent $1 million to purchase WEAF and Washington sister station WCAP, shut down the latter station, merged its facilities with surviving station WRC; the division's ownership was split among RCA, its founding corporate parent General Electric and Westinghouse. NBC started broadcasting on November 15, 1926. WEAF and WJZ, the flagships of the two earlier networks, were operated side-by-side for about a year as part of the new NBC. On January 1, 1927, NBC formally divided their respective marketing strategies: the "Red Network" offered commercially sponsored entertainment and music programming. Various histories of NBC suggest the color designations for the two networks came from the color of the pushpins NBC engineers used to designate affiliate stations of WEAF and WJZ, or from the use of double-ended red and blue colored pencils. On April 5, 1927, NBC expanded to the West Coast with the launch of the NBC Orange Network known as the Pacific Coast Network.
This was followed by the debut of the NBC Gold Network known as the Pacific Gold Network, on October 18, 1931. The Orange Network carried Red Network programming, the Gold Network carried programming from the Blue Network; the Orange Network recreated Eastern Red Network programming for West Coast stations at KPO in San Francisco. In 1936, the Orange Network affiliate stations became part of the Red Network, at the same time the Gold Network became part of the Blue Network. In the 1930s, NBC developed a network for shortwave radio stations, called the NBC White Network. In 1927, NBC moved its operations to 711 Fifth Avenue in Manhattan, occupying the upper floors of a building de
WPXT is a CW-affiliated television station licensed to Portland, United States, serving southern Maine and eastern and northern New Hampshire. It broadcasts a high definition digital signal on UHF channel 43 from a transmitter in South Gray along I-95/Maine Turnpike/Gold Star Memorial Highway. Owned by the Hearst Television subsidiary of Hearst Communications, it is part of a duopoly with Poland Spring-licensed ABC affiliate WMTW; the station signed-on September 14, 1986 as Maine's first independent station and the first new commercial station to launch in the Portland market in 32 years. After a few weeks as an independent, it became a charter affiliate with Fox on October 6. In 1996, the station's original owner, Bride Communications, entered bankruptcy and WPXT was sold to Pegasus Broadcasting. In 2001, WPXT switched to The WB due to a monetary dispute between Fox; this left Portland with no over-the-air Fox affiliate until early 2003, when Pax station WMPX-TV took the affiliation, becoming WPFO.
In the interim, programming from the network was provided on WFXT for those living on the New Hampshire side of the market, on Foxnet for Portland/Auburn-area cable subscribers. Pegasus declared bankruptcy in June 2004 over a dispute with DirecTV over marketing of the direct broadcast satellite service in rural areas; the Pegasus station group was sold in August 2006 to private investment firm CP Media, LLC of Wilkes-Barre, Pennsylvania for $55.5 million. CP Media formed a new broadcast company, New Age Media; as a WB affiliate, WPXT was branded on-air as "Maine's WB 51", but in 2004, changed to "Maine's WB" to reflect its status as the only over-the-air WB affiliate in the state. Although Bangor and Presque Isle had affiliates, they were only provided on cable through The WB 100+. On January 24, 2006, Time Warner and CBS Corporation announced that they would merge the broadcast operations of The WB and UPN to form The CW Television Network. On March 9, it was announced. On May 1, it was made public sister station WPME would affiliate with MyNetworkTV.
With the new affiliation, WPXT's branding became "The CW Portland". In 2007, WPXT changed its on-air branding to reflect its call letters rather than a city. WPXT ceased analog transmission August 2008 due to transmitter failure. On May 2, 2011, WPXT signed-on a new second digital subchannel to become the area's MeTV affiliate. On November 7, 2016, Escape was added to 51.3 subchannel slot. New Age Media announced in March 2012 that it would sell WPXT to Tyche Broadcasting for $75,000; the deal was contingent on WPME's concurrent sale from MPS Media to Triumph Broadcasting. On November 9, 2012, WPXT filed a non-consummation notice to the FCC, meaning the transaction is nulled and void. On February 13, 2013, New Age Media filed to sell WPXT to Ironwood Communications for $1,525,000; the FCC granted its approval of the sale on April 2. The sale was consummated on May 20. On March 22, 2018, MyNetworkTV, Escape and Laff programming was moved to the third and fifth subchannels of WPXT. Hearst Television announced its acquisition of WPXT on July 30, 2018.
The sale was approved on September 12 and was completed on September 21, 2018. With Hearst's preference for its main station in the market to carry the MeTV affiliation, MeTV and H&I exchanged places, with MeTV moving to WMTW-DT2 and H&I going to WPXT-DT2, Laff going from WPXT-DT2 to WMTW-DT3, with Escape going to WPXT-DT3; the syndicated programming on WPXT-DT3's "WPME" service was removed, MyNetworkTV programming now airs in place of H&I's primetime, or sometimes during the late night hours on WPXT-DT2, an arrangement similar to the setup for the third subchannel of sister station KCCI in Des Moines, Iowa. Syndicated programming on WPXT includes Divorce Court, The People's Court, How I Met Your Mother, Modern Family, Extra, TMZ on TV, Chicago P. D. among others. Throughout its history, WPXT has produced and aired several local programs. For many years, WPXT produced its own local newscasts. For a time, the station's nightly prime time news at 10 was simulcasted on sister station WPME. WPXT produced a weeknight broadcast at 7 on that station at one point but the show was canceled due to poor ratings and inconsistent viewership.
It made national headlines a week before the 2000 Presidential election when reporter Erin Fehlau revealed Republican candidate George W. Bush had been convicted for driving under the influence of alcohol 24 years earlier. On June 15, 2002, after shuttering its own news operation, WPXT entered into a news share agreement with Maine's two NBC affiliates, WCSH and WLBZ; this arrangem
Ultra high frequency
Ultra high frequency is the ITU designation for radio frequencies in the range between 300 megahertz and 3 gigahertz known as the decimetre band as the wavelengths range from one meter to one tenth of a meter. Radio waves with frequencies above the UHF band fall into the super-high frequency or microwave frequency range. Lower frequency signals fall into lower bands. UHF radio waves propagate by line of sight, they are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, numerous other applications. The IEEE defines the UHF radar band as frequencies between 1 GHz. 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. Radio waves in the UHF band travel entirely by line-of-sight propagation and ground reflection. 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 and other common objects and diffraction from these objects can cause fading due to multipath propagation in built-up urban areas. Atmospheric moisture reduces, or attenuates, the strength of UHF signals over long distances, the attenuation increases with frequency. UHF TV signals are 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 and to shorter distances by local terrain, it allows the same frequency channels to be reused by other users in neighboring geographic areas. Public safety, business communications and personal radio services such as GMRS, PMR446, UHF CB are found on UHF frequencies as well as IEEE 802.11 wireless LANs. The 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; when conditions are right, UHF radio waves can travel long distances by tropospheric ducting as the atmosphere warms and cools throughout the day.
The length of an antenna is related to the length of the radio waves used. Due to the short wavelengths, UHF antennas are conveniently short. 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, for portable wireless devices. Omnidirectional UHF antennas used on mobile devices are short whips, sleeve dipoles, rubber ducky antennas or the planar inverted F antenna 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 allow high gain antennas to be conveniently small. High gain antennas for point-to-point communication links and UHF television reception are 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 and turnstile antennas are used since satellites employ circular polarization, not sensitive to the relative orientation of the transmitting and receiving antennas. For television broadcasting specialized vertical radiators that are modifications of the slot antenna or reflective array antenna are used: the slotted cylinder, zig-zag, panel antennas. 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, public safety, military purposes. Many personal radio services use frequencies allocated in the UHF band, although exact frequencies in use differ 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. UHF citizens band: 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 and Territory Government, Rail industry and Mobile-Satellite 430–450 MHz: Amateur radio 470–806 MHz: Terrestrial television 1452–1492 MHz: Digital Audio Broadcasting Many other frequency assignments for Canada and Mexico are similar to their US counterparts 380–399.9 MHz: Terrestrial Trunked Radio service for emergency use 430–440 MHz: Amateur ra
Thomas Jefferson was an American statesman, lawyer and Founding Father who served as the third president of the United States from 1801 to 1809. He had served as the second vice president of the United States from 1797 to 1801; the principal author of the Declaration of Independence, Jefferson was a proponent of democracy and individual rights motivating American colonists to break from the Kingdom of Great Britain and form a new nation. Jefferson was of English ancestry and educated in colonial Virginia, he graduated from the College of William & Mary and practiced law, with the largest number of his cases concerning land ownership claims. During the American Revolution, he represented Virginia in the Continental Congress that adopted the Declaration, drafted the law for religious freedom as a Virginia legislator, served as the 2nd Governor of Virginia from 1779 to 1781, during the American Revolutionary War, he became the United States Minister to France in May 1785, subsequently the nation's first secretary of state under President George Washington from 1790 to 1793.
Jefferson and James Madison organized the Democratic-Republican Party to oppose the Federalist Party during the formation of the First Party System. With Madison, he anonymously wrote the controversial Kentucky and Virginia Resolutions in 1798 and 1799, which sought to strengthen states' rights by nullifying the federal Alien and Sedition Acts; as president, Jefferson pursued the nation's shipping and trade interests against Barbary pirates and aggressive British trade policies. He organized the Louisiana Purchase doubling the country's territory; as a result of peace negotiations with France, his administration reduced military forces. He was reelected in 1804. Jefferson's second term was beset with difficulties at home, including the trial of former vice president Aaron Burr. American foreign trade was diminished when Jefferson implemented the Embargo Act of 1807, responding to British threats to U. S. shipping. In 1803, Jefferson began a controversial process of Indian tribe removal to the newly organized Louisiana Territory, he signed the Act Prohibiting Importation of Slaves in 1807.
Jefferson, while a planter and politician, mastered many disciplines, which ranged from surveying and mathematics to horticulture and mechanics. He was an architect in the classical tradition. Jefferson's keen interest in religion and philosophy led to his presidency of the American Philosophical Society. A philologist, Jefferson knew several languages, he corresponded with many prominent people. His only full-length book is Notes on the State of Virginia, considered the most important American book published before 1800. After retiring from public office, Jefferson founded the University of Virginia. Although regarded as a leading spokesman for democracy and republicanism in the era of the Enlightenment, Jefferson's historical legacy is mixed; some modern scholarship has been critical of Jefferson's private life, pointing out the contradiction between his ownership of the large numbers of slaves that worked his plantations and his famous declaration that "all men are created equal." Another point of controversy stems from the evidence that after his wife Martha died in 1782, Jefferson fathered children with Martha's half-sister, Sally Hemings, his slave.
Despite this, presidential scholars and historians praise his public achievements, including his advocacy of religious freedom and tolerance in Virginia. Jefferson continues to rank among U. S. presidents. Thomas Jefferson was born on April 13, 1743, at the family home in Shadwell in the Colony of Virginia, the third of ten children, he was of English, Welsh and was born a British subject. His father Peter Jefferson was a surveyor who died when Jefferson was fourteen. Peter Jefferson moved his family to Tuckahoe Plantation in 1745 upon the death of William Randolph, the plantation's owner and Jefferson's friend, who in his will had named him guardian of his children; the Jeffersons returned to Shadwell in 1752, where Peter died in 1757. Thomas inherited 5,000 acres of land, including Monticello, he assumed full authority over his property at age 21. Jefferson began his childhood education beside the Randolph children with tutors at Tuckahoe. Thomas' father, was self-taught, regretting not having a formal education, he entered Thomas into an English school early, at age five.
In 1752, at age nine, he began attending a local school run by a Scottish Presbyterian minister and began studying the natural world, for which he grew to love. At this time he began studying Latin and French, while learning to ride horses. Thomas read books from his father's modest library, he was taught from 1758 to 1760 by Reverend James Maury near Gordonsville, where he studied history and the classics while boarding with Maury's family. During this period Jefferson came to know and befriended various American Indians, including the famous Cherokee chief, who stopped at Shadwell to visit, on their way to Williamsburg to trade. During the two years Jefferson was with the Maury family, he traveled to Williamsburg and was a guest of Colonel Dandridge, father of Martha Washington. In Williamsburg the young Jefferson met and came to admire Patrick Henry, eight ye
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government created by statute to regulate interstate communications by radio, wire and cable. The FCC serves the public in the areas of broadband access, fair competition, radio frequency use, media responsibility, public safety, homeland security; the FCC was formed by the Communications Act of 1934 to replace the radio regulation functions of the Federal Radio Commission. The FCC took over wire communication regulation from the Interstate Commerce Commission; the FCC's mandated jurisdiction covers the 50 states, the District of Columbia, the Territories of the United States. The FCC provides varied degrees of cooperation and leadership for similar communications bodies in other countries of North America; the FCC is funded by regulatory fees. It has an estimated fiscal-2016 budget of US $388 million, it has 1,688 federal employees, made up of 50% males and 50% females as of December, 2017. The FCC's mission, specified in Section One of the Communications Act of 1934 and amended by the Telecommunications Act of 1996 is to "make available so far as possible, to all the people of the United States, without discrimination on the basis of race, religion, national origin, or sex, efficient and world-wide wire and radio communication services with adequate facilities at reasonable charges."
The Act furthermore provides that the FCC was created "for the purpose of the national defense" and "for the purpose of promoting safety of life and property through the use of wire and radio communications."Consistent with the objectives of the Act as well as the 1999 Government Performance and Results Act, the FCC has identified four goals in its 2018-22 Strategic Plan. They are: Closing the Digital Divide, Promoting Innovation, Protecting Consumers & Public Safety, Reforming the FCC's Processes; the FCC is directed by five commissioners appointed by the President of the United States and confirmed by the United States Senate for five-year terms, except when filling an unexpired term. The U. S. President designates one of the commissioners to serve as chairman. Only three commissioners may be members of the same political party. None of them may have a financial interest in any FCC-related business. † Commissioners may continue serving until the appointment of their replacements. However, they may not serve beyond the end of the next session of Congress following term expiration.
In practice, this means that commissioners may serve up to 1 1/2 years beyond the official term expiration dates listed above if no replacement is appointed. This would end on the date that Congress adjourns its annual session no than noon on January 4; the FCC is organized into seven Bureaus, which process applications for licenses and other filings, analyze complaints, conduct investigations and implement regulations, participate in hearings. The Consumer & Governmental Affairs Bureau develops and implements the FCC's consumer policies, including disability access. CGB serves as the public face of the FCC through outreach and education, as well as through their Consumer Center, responsible for responding to consumer inquiries and complaints. CGB maintains collaborative partnerships with state and tribal governments in such areas as emergency preparedness and implementation of new technologies; the Enforcement Bureau is responsible for enforcement of provisions of the Communications Act 1934, FCC rules, FCC orders, terms and conditions of station authorizations.
Major areas of enforcement that are handled by the Enforcement Bureau are consumer protection, local competition, public safety, homeland security. The International Bureau develops international policies in telecommunications, such as coordination of frequency allocation and orbital assignments so as to minimize cases of international electromagnetic interference involving U. S. licensees. The International Bureau oversees FCC compliance with the international Radio Regulations and other international agreements; the Media Bureau develops and administers the policy and licensing programs relating to electronic media, including cable television, broadcast television, radio in the United States and its territories. The Media Bureau handles post-licensing matters regarding direct broadcast satellite service; the Wireless Telecommunications Bureau regulates domestic wireless telecommunications programs and policies, including licensing. The bureau implements competitive bidding for spectrum auctions and regulates wireless communications services including mobile phones, public safety, other commercial and private radio services.
The Wireline Competition Bureau develops policy concerning wire line telecommunications. The Wireline Competition Bureau's main objective is to promote growth and economical investments in wireline technology infrastructure, development and services; the Public Safety and Homeland Security Bureau was launched in 2006 with a focus on critical communications infrastructure. The FCC has eleven Staff Offices; the FCC's Offices provide support services to the Bureaus. The Office of Administrative Law Judges is responsible for conducting hearings ordered by the Commission; the hearing function includes acting on interlocutory requests filed in the proceedings such as petitions to intervene, petitions to enlarge issues, contested discovery requests. An Administrative Law Judge, appointed under the Administrative Procedure Act, presides at the hearing during which documents and sworn testimony are received in evidence, witnesses are cross-examined. At the co
Very high frequency
High frequency is the ITU designation for the range of radio frequency electromagnetic waves from 30 to 300 megahertz, with corresponding wavelengths of ten meters to one meter. Frequencies below VHF are denoted high frequency, the next higher frequencies are known as ultra high frequency. Common uses for radio waves in the VHF band are FM radio broadcasting, television broadcasting, two way land mobile radio systems, long range data communication up to several tens of kilometers with radio modems, amateur radio, marine communications. Air traffic control communications and air navigation systems work at distances of 100 kilometres or more to aircraft at cruising altitude. In the Americas and many other parts of the world, VHF Band I was used for the transmission of analog television; as part of the worldwide transition to digital terrestrial television most countries require broadcasters to air television in the VHF range using digital rather than analog format. Radio waves in the VHF band propagate by line-of-sight and ground-bounce paths.
They do not follow the contour of the Earth as ground waves and so are blocked by hills and mountains, although because they are weakly refracted by the atmosphere they can travel somewhat beyond the visual horizon out to about 160 km. They can penetrate building walls and be received indoors, although in urban areas reflections from buildings cause multipath propagation, which can interfere with television reception. Atmospheric radio noise and interference from electrical equipment is less of a problem in the band than at lower frequencies; the VHF band is the first band at which efficient transmitting antennas are small enough that they can be mounted on vehicles and portable devices, so the band is used for two-way land mobile radio systems, such as walkie-talkies, two way radio communication with aircraft and ships. When conditions are right, VHF waves can travel long distances by tropospheric ducting due to refraction by temperature gradients in the atmosphere. For analog TV, VHF transmission range is a function of transmitter power, receiver sensitivity, distance to the horizon, since VHF signals propagate under normal conditions as a near line-of-sight phenomenon.
The distance to the radio horizon is extended over the geometric line of sight to the horizon, as radio waves are weakly bent back toward the Earth by the atmosphere. An approximation to calculate the line-of-sight horizon distance is: distance in nautical miles = 1.23 × A f where A f is the height of the antenna in feet distance in kilometers = 12.746 × A m where A m is the height of the antenna in meters. These approximations are only valid for antennas at heights that are small compared to the radius of the Earth, they may not be accurate in mountainous areas, since the landscape may not be transparent enough for radio waves. In engineered communications systems, more complex calculations are required to assess the probable coverage area of a proposed transmitter station; the accuracy of these calculations for digital TV signals is being debated. VHF is the first band at which wavelengths are small enough that efficient transmitting antennas are short enough to mount on vehicles and handheld devices, a quarter wave whip antenna at VHF frequencies is 25 cm to 2.5 meter long.
So the VHF and UHF wavelengths are used for two-way radios in vehicles and handheld transceivers and walkie-talkies. Portable radios use whips or rubber ducky antennas, while base stations use larger fiberglass whips or collinear arrays of vertical dipoles. For directional antennas, the Yagi antenna is the most used as a high gain or "beam" antenna. For television reception, the Yagi is used, as well as the log-periodic antenna due to its wider bandwidth. Helical and turnstile antennas are used for satellite communication since they employ circular polarization. For higher gain, multiple Yagis or helicals can be mounted together to make array antennas. Vertical collinear arrays of dipoles can be used to make high gain omnidirectional antennas, in which more of the antenna's power is radiated in horizontal directions. Television and FM broadcasting stations use collinear arrays of specialized dipole antennas such as batwing antennas. Certain subparts of the VHF band have the same use around the world.
Some national uses are detailed below. 50–54 MHz: Amateur Radio 6-meter band. 108–118 MHz: Air navigation beacons VOR and Instrument Landing System localizer. 118–137 MHz: Airband for air traffic control, AM, 121.5 MHz is emergency frequency 144–148 MHz: Amateur Radio 2-meter band. The VHF TV band in Australia was allocated channels 1 to 10-with channels 2, 7 and 9 assigned for the initial services in Sydney and Melbourne, the same channels were assigned in Brisbane and Perth. Other capital cities and regional areas used a combination of these and other frequencies as available; the initial commercial services in Hobart and Darwin were allocated channels 6 and 8 rather than 7 or 9. By the early 1960s it became apparent that the 10 VHF channels were insufficient to support the growth of television services; this was rectified by the addition of th