KNEW

KNEW may mean:
- two broadcast stations in San Francisco:
- KNEW AM 990
- former KNEW-TV 32 (now KMTP-TV)
- ICAO airport code for New Orleans Lakefront Airport

Broadcast station

A broadcast station may be:
- a radio station
- a television station It does not include television networks or radio networks. See also: broadcasting

San francisco

: The City and County of San Francisco (2004 estimated population 744,230) is the fourth-largest city in the state of California, in the United States. A consolidated city-county, mainland San Francisco is located on the tip of the San Francisco Peninsula. Insular San Francisco includes several islands in the San Francisco Bay and the Golden Gate Strait, notably Alcatraz, Treasure Island, and the Farallon Islands 27 miles offshore in the Pacific Ocean and also most of the privately owned Red Rock Island near the Richmond-San Rafael Bridge. (See Islands of San Francisco Bay) The city is a focal point of the San Francisco Bay Area, and forms part of the greater San Jose-San Francisco-Oakland Combined Statistical Area (CSA), whose population is over 7 million. U.S. census data show that San Francisco has the highest population density of any major U.S. city aside from New York City. The first Europeans to settle in San Francisco were the Spanish, in 1776. With the advent of the California gold rush in 1848 the city entered a period of rapid growth. Devastated by the 1906 San Francisco earthquake, the city was quickly rebuilt. The phoenix on the city's flag represents San Francisco's "rebirth" from the ashes of the fire that resulted from the quake. Long enjoying a bohemian reputation the city became a counterculture magnet in the second half of the 20th century. It was a center of the dot-com boom and explosive growth of the internet at the end of the century. San Francisco has unique characteristics when compared to other major cities in the U.S., including its steep rolling hills, an eclectic mix of architecture including both Victorian style houses and modern skyscrapers, and unmatched physical beauty, surrounded by the Pacific Ocean and San Francisco Bay. San Francisco's famous hallmarks include its cable cars and the Golden Gate Bridge, which are recognized worldwide.
History
Golden Gate Bridge European visitors to the Bay Area were preceded 10,000 to 20,000 years earlier by Native Americans. When Europeans arrived, they found the area inhabited by the Yelamu tribe, belonging to a linguistic grouping later called the Ohlone (a Miwok Indian word meaning "western people") living in the coastal area between Point Sur and the San Francisco Bay. San Francisco's characteristic foggy weather and geography led early European explorers, including Juan Cabrillo and Sir Francis Drake (who would instead land a few miles north in Point Reyes), to pass by the Golden Gate and miss the San Francisco Bay. Eventually, a Spanish party, led by Don Gaspar de Portolà, discovered the bay in 1770, claiming it in the name of Spain. In 1776, Juan Bautista de Anza arrived and established the sites for the Presidio of San Francisco and Mission San Francisco de Asis (named for Saint Francis of Assisi and now popularly known as "Mission Dolores"). In 1792 British explorer George Vancouver set up a small settlement near the village of Yerba Buena (later downtown San Francisco) which became a small base for English, Russian, and other European fur traders, explorers, and settlers. Due to its distance from Mexico City and the decline of Spanish power, the area was isolated, remaining sparsely populated and undeveloped. It became part of an independent Mexico in 1821. Following the passing of the Secularization Act of 1833, effectively ending the Mission period, Mission San Francisco de Asis was abandoned. The local indigenous tribes of Ohlone and Miwok had became virtually extinct by this time due to disease and warfare with the European settlers. In addition to Spanish and European settlers, Russian colonists also visited the Bay area. From 1770, lasting through 1841, Russia colonized an area that ranged from Alaska south to Fort Ross in Sonoma County, California. The naming of San Francisco's Russian Hill neighborhood is attributed to the remains of Russian fur-traders and sailors found there. Serious development by non-Spanish speakers began in 1822, when William Richardson, an English whaler redeveloped a section of Yerba Buena in what is now Portsmouth Square in Chinatown. Yerba Buena remained a small town until the Mexican-American War broke out in 1846. The British Empire briefly entertained the idea of purchasing the bay from Mexico in 1841, claiming it would "Secure to Great Britain all the advantages of the finest port in the Pacific for her commercial speculations in time of peace, and in war for more easily securing her maritime ascendency". However little came of this, and San Francisco become a prize of United States continental imperialism rather than that of British thalassocratic power. A naval force under Commodore John D. Sloat claimed it in the name of the United States and renamed it "San Francisco" on January 30, 1847. Situated at the tip of a windswept peninsula without water or firewood, San Francisco lacked most of the basic facilities for a nineteenth century settlement. These natural disadvantages forced the town's residents to bring water, fuel and food to the site. The first of many environmental transformations was the city's reliance on filled marshlands for real estate. Much of the present downtown is built over the former Yerba Buena Cove, granted to the city by military governor Stephen Watts Kearny in 1847. Stephen Watts Kearny The California gold rush starting in 1848 led to a large boom in population, including considerable immigration. Between January 1848 and December 1849, the population of San Francisco increased from 1,000 to 25,000. This included many workers from China who came to work in the gold mines and later on the Transcontinental Railroad. The Chinatown district of the city became and is still one of the largest in the country; the city as a whole is roughly one-fifth Chinese, one of the largest concentrations outside of China. Many businesses founded to service the growing population exist today, notably Levi Strauss & Co. clothing, Ghirardelli chocolate, and Wells Fargo bank. Many famous railroad, banking, and mining tycoons or "robber barons" such as Charles Crocker, Mark Hopkins, Collis P. Huntington, and Leland Stanford settled in the city in its Nob Hill neighborhood. The sites of their mansions are now famous and expensive San Francisco hotels (Mark Hopkins Hotel and the Huntington Hotel). Huntington Hotel, 1856.]] As in many mining towns, the social climate in early San Francisco was chaotic. This was exacerbated by squabbling in the United States Senate, where the Compromise of 1850 was igniting a fierce fight over slavery. Committees of Vigilance were formed in 1851, and again in 1856, in response to crime and government corruption, but also had a strong element of anti-immigrant violence, and arguably created more lawlessness than they eliminated. This popular militia movement lynched 12 people, kidnapped hundreds of Irishmen and government militia members, and forced several elected officials to resign. The Committee of Vigilance relinquished power both times after it decided the city had been "cleaned up." This mob activity later focused on Chinese immigrants, creating many race riots. These riots culminated in the creation of the Chinese Exclusion Act in 1882 that aimed to reduce Chinese immigration to the United States by limiting immigration to males and reducing numbers of immigrants allowed in the city. The law was not repealed until 1943. Chinese Exclusion Act San Francisco County was one of the original counties of California, created in 1850 at the time of statehood. The parts of the county not in the city limits were split off to form San Mateo County in 1856. San Francisco became America's largest city west of the Mississippi River, until it lost that title to Los Angeles. It was also briefly the state capital in 1851, until San José received the title. (Sacramento is the current capital.) In autumn of 1855, a ship bearing refugees from an ongoing cholera epidemic in the far east (authorities disagree as to whether this was the S.S. Sam or the S.S. Carolina) docked in San Francisco. As the city's rapid gold-rush area population growth had significantly outstripped the development of infrastructure, including sanitation, a serious cholera epidemic quickly broke out. The responsibility for caring for the indigent sick had previously rested on the state, but faced with the San Francisco cholera epidemic, the state legislature devolved this responsibility to the counties, setting the precedent for California's system of county hospitals for the poor still in effect today. The Sisters of Mercy were contracted to run San Francisco's first county hospital at the height of the cholera epidemic, and in 1857, the order opened its own charity hospital, Mercy Hospital of San Francisco, which is still in operation today at its original location on Stanyan Street. By the 1890s, San Francisco was suffering from Boss politics and corruption, and was ripe for political reform. Adolph Sutro ran for mayor in 1894 under the auspices of the Populist Party and won handily without campaigning. Unfortunately, except for the Sutro Baths, Mayor Sutro substantially failed in his efforts to improve the city. The next mayor, James D. Phelan elected in 1896, was more successful, pushing through a new city charter that allowed for the ability to raise funds through bond issues. He was able to get bonds passed to construct a new sewer system, seventeen new schools, two parks, a hospital, and a main library. After leaving office in 1901, Phelan became interested in remaking San Francisco into a grand and modern Paris of the West. When the San Francisco Art Association asked him to draft a plan for the beautification of the city, he hired famed architect Daniel Burnham. Burnham and Phelan's plan was ambitious, envisioning a 50-year effort to transform the city with wide diagonal boulevards creating open spaces and squares as they crossed the orthogonal grid of existing streets. Some parts of the plan were eventually implemented, including an Opera house to the north of City Hall, a subway under Market Street, and a waterfront boulevard (The Embarcadero) circling the city. In 1900, a ship from China brought with it rats infected with bubonic plague. Mistakenly believing that interred corpses contributed to the transmission of plague, and possibly also motivated by the opportunity for profitable land speculation, city leaders banned all burials within the city. Cemeteries moved to the undeveloped area just south of the city limit, now the town of Colma, California. A fifteen-block section of Chinatown was quarantined while city leaders squabbled over the proper course to take, but the outbreak was finally eradicated by 1905. However, the problem of existing cemeteries and the shortage of land in the city remained. In 1912 (with fights extending until 1942), all remaining cemeteries in the city were evicted to Colma, where the dead now outnumber the living by more than a thousand to one. The above-ground Columbarium of San Francisco was allowed to remain, as well as the historic cemetery at the Mission Dolores Church and The San Francisco National Cemetery in the Presidio of San Francisco. On April 18 1906, a devastating earthquake resulted from the rupture of over 270 miles of the San Andreas Fault, from San Juan Bautista to Eureka, centered immediately offshore of San Francisco. The quake is estimated by the USGS to have had a magnitude of 7.8 on the Richter scale. Water mains ruptured throughout San Francisco, and the fires that followed burned out of control for days, destroying approximately 80% of the city, including almost all of the downtown core. Many residents were trapped between the water on three sides and the approaching fire, and a mass evacuation (similar to that of the later Battle of Dunkirk) across the Bay saved thousands. Refugee camps were also set up in Golden Gate Park, Ocean Beach, and other undeveloped sections of the city. The official death toll at the time was 478, although it was officially revised in 2005 to 3,000+. The initial low death toll was concocted by civic, state, and federal officials who felt that reporting the actual numbers would hurt rebuilding and redevelopment efforts, as well as city and national morale. Ocean Beach In 1915, the city hosted the Panama-Pacific Exposition, officially to celebrate the opening of the Panama Canal, but also as a showcase of the vibrant completely rebuilt city less than a decade after the Earthquake. After the exposition ended, all of its grand buildings were demolished except for the Palace of Fine Arts which survives today in an abbreviated form. The San Francisco-Oakland Bay Bridge was opened in 1936 and the Golden Gate Bridge in 1937. During World War II, San Francisco was the major mainland supply point and port of embarkation for the war in the Pacific. The War Memorial Opera House in San Francisco has been the site of some significant post World War II history. In 1945, the conference that formed the United Nations was held there, with the UN Charter being signed on June 26. Additionally the Treaty of San Francisco which formally ended war with Japan and established peaceful relations, was drafted and signed here six years later in 1951. After World War II, many American military personnel who fell in love with the city during leaving to or returning from the Pacific, settled in the city prompting the creation of the Sunset District and Visitacion Valley. During this period, Caltrans commenced an aggressive freeway construction program in the Bay Area. However, Caltrans soon encountered strong resistance in San Francisco, for the city's high population density meant that virtually any right-of-way would displace a large number of people. Caltrans tried to minimize displacement (and its land acquisition costs) by building double-decker freeways, but the crude state of civil engineering at that time resulted in construction of some embarrassingly ugly freeways which ultimately turned out to be seismically unsafe. In 1959, the Board of Supervisors voted to halt construction of any more freeways in the city, an event known as the Freeway Revolt. Although some minor modifications have been allowed to the ends of existing freeways, the city's anti-freeway policy has remained in place ever since. In 1989, the Loma Prieta earthquake destroyed the Embarcadero Freeway and portions of the so-called Central Freeway. Over the course of several referenda, San Francisco's residents elected not to rebuild either structure. The neighborhoods once covered by these freeways have been rebuilt, and the restoration of the Embarcadero, San Francisco's historic bay waterfront, as a public space has been especially successful. In the 1950s San Francisco hired Harvard graduate Justin Herman to head the redevelopment agency for the city and county. Justin Herman began an aggressive campaign to renew blighted areas of the city. Enacting eminent domain whenever necessary, he set upon a plan to tear down huge areas of the city and replace them with modern construction. Critics accused Herman of racism for what was perceived as attempts to create segregation and displacement of African-Americans. Many African-Americans were forced to move from their homes near the Fillmore jazz district to newly constructed projects such as the near the naval base Hunter's Point or even to cities such as Oakland. He began leveling entire areas in San Francisco's Western Addition and Japantown neighborhoods. His planning led to the creation of Embarcadero Center, the Embarcadero Freeway, Japantown, the Geary Street superblocks, and Yerba Buena Gardens. San Francisco has often been a magnet for America's counterculture. During the 1950s, City Lights Bookstore in the North Beach neighborhood was an important publisher of Beat Generation literature. Some of the story of the evolving arts scene of the 1950s is told in the article San Francisco Renaissance. During the latter half of the following decade, the 1960s, San Francisco was the center of hippie and other alternative culture. In 1966 the Church Of Satan opened their headquarters, and in 1967 thousands of young people poured into the Haight-Ashbury district during what became known as the Summer of Love. At this time, the "San Francisco sound" emerged as an influential force in rock music, with such acts as the Jefferson Airplane and the Grateful Dead achieving international prominence, blurring the boundaries between folk, rock and jazz traditions and further developing the lyrical content of rock. During the 1980s and 1990s San Francisco became a major focal point in the North American--and international-- punk, thrash metal, and rave scenes. On the rave scene, the city was the first to host the Love Parade outside its birthplace of Berlin, Germany in 2004. It was also a hot spot during the 1980's for comedians like Ellen DeGeneres and Robin Williams who got major career boosts thanks to the presence of the city's popular comedy clubs. San Francisco's frontier spirit and wild and ribald character caused it to become known as a gay mecca beginning in the nineteenth century. This reputation was enforced greatly during World War II, when thousands of gay male soldiers spent time in the City, while en route to and from the Pacific theater. The late 1960s also brought in a new wave of lesbians and gays who were more radical and less mainstream and who had flocked to San Francisco not only for its gay-friendly reputation, but for its reputation as a radical, left-wing epicenter. These new residents were the prime movers of Gay Liberation and often lived communally, buying decrepit Victorians in the Haight and fixing them up. When drugs and violence began to become a serious problem in the Haight, many lesbians and gays simply moved "over the hill", to the Castro replacing Irish-Americans who had moved to the more affluent and culturally homogenous suburbs. The Castro became known as a Gay Mecca, and its gay population swelled as significant numbers of gay people moved to San Francisco in the 1970s and 1980s. The growth of the gay population caused tensions with some of the established ethnic groups in the western part of the city. On November 27, 1978 Dan White, a former member of the Board of Supervisors and former police officer, assassinated the city's mayor George Moscone and San Francisco's first openly gay elected official, Supervisor Harvey Milk (see "Twinkie Defense"). The murders and the subsequent trial were marked both by candlelight vigils and riots within the gay community. In the 1980s, the AIDS virus wreaked havoc on the gay male community there. Today, the gay population of the city is estimated to be approximately 15%, and gays remain an important force in the city's life. San Francisco has a higher percentage of gays and lesbians than any other major US city. During the administration of Mayor Dianne Feinstein (1978-1988), San Francisco saw a development boom referred to as "Manhattanization." Many large skyscrapers were built — primarily in the Financial District — but the boom also included high-rise condominiums in some residential neighborhoods. An opposition movement gained traction among those who felt the skyscrapers ruined views and destroyed San Francisco's unique character. Similar to the freeway revolt in the city decades earlier, a "skyscraper revolt" forced the city to embed height restrictions in the planning code. For many years, the limits slowed construction of new skyscrapers, but recent (2000-2005) housing pressures have led to master plan changes which will allow new construction of high-rise structures along The Embarcadero and in the South of Market district. South of Market During the 1980s, homeless people began appearing in large numbers in the city, the result of multiple factors including the closing of state institutions for the mentally ill, and social changes which increased the availability of addictive drugs. Combined with San Francisco's attractive environment and generous welfare policies the problem soon became endemic. Mayor Art Agnos (1988-92) was the first to attack the problem, and not the last; it is a top issue for San Franciscans even today. Agnos allowed the homeless to camp in the Civic Center park, which led to its title of "Camp Agnos." The failure of this policy led to his losing the election to Frank Jordan in 1991. Jordan launched the "MATRIX" program the next year, which aimed to displace the homeless through aggressive police action. And it did displace them - to the rest of the city. His successor, Willie Brown, was able to largely ignore the problem, riding on the strong economy into a second term. Present mayor Gavin Newsom's policy on the homeless is the controversial "Care Not Cash" program, which calls for ending the city's generous welfare policies towards the homeless and instead placing them in affordable housing and requiring them to attend city funded drug rehabilitation and job training programs. On October 17, 1989, an earthquake measuring 7.1 on the Richter magnitude scale struck on the San Andreas Fault near Loma Prieta Peak in the Santa Cruz mountains, approximately 70 miles south of San Francisco, a few minutes before game 3 of the 1989 World Series. The quake severely damaged many of the city's freeway's including the Embarcadero Freeway and the Central Freeway. The damage to these freeways was so extensive that they were eventually demolished. The quake also caused extensive damage in the Marina District and the South of Market. Known in most of the United States as the "World Series Quake," but in California and by seismologists as the Loma Prieta earthquake, it caused significant destruction and loss of life throughout the greater Bay Area. During the dot-com boom of the 1990s, large numbers of entrepreneurs and computer software professionals moved into the city, followed by marketing and sales professionals, and changed the social landscape as once poorer neighborhoods became gentrified. The rising rents forced many people and businesses to leave, and this caused considerable tension in the city's politics. The resulting backlash resulted in a progressive majority winning control of the Board of Supervisors in the 2000 election. By 2001, the boom was over, and many people left San Francisco. South of Market, where many dot-com companies were located, had been bustling and crowded with few vacancies, but by 2002 was a virtual wasteland of empty offices and for-rent signs. Much of the boom was blamed for the city's "fastest shrinking population", reducing the city's population by 30,000 in just a few years. While the boom has helped put an ease on the city's apartment rents, the city remains expensive nonetheless. In February 2004, San Francisco became the first city in the United States to grant marriage to gay couples when Mayor Gavin Newsom, elected the previous year, ordered the City Clerks office to issue same-sex marriage licenses. The California Supreme Court later invalidated these licenses, holding that Newsom had acted without proper authority. In 2005 San Francisco hosted the United Nations annual World Environment Day conference, the first in the United States, and banned outdoor smoking in all city-owned parks, plazas and public sports venues. Also as of December 2005, the crime rate has gone up, with more than 90 killngs throughout the year. San Francisco is also facing serious budget deficits, and, for such a small city, the homeless problem is still one of the worst in America.
Geography and climate
banned outdoor smoking Landsat 7]] San Francisco lies near the San Andreas Fault and Hayward Fault, two major sources of earthquake activity in California. The most serious earthquake, in 1906, is mentioned above. Earlier significant quakes rocked the city in 1851, 1858, 1865, and 1868. The Daly City Earthquake of 1957 caused some damage. The Loma Prieta earthquake of 1989, which also did significant damage to parts of the city, is also famous for having interrupted a World Series baseball game between the Bay Area's two Major League Baseball teams, the San Francisco Giants and the Oakland Athletics. The threat of another major earthquake like the 1906 one plays a major role in the city's infrastructure development. New buildings must be built to very high structural standards, while many dollars must be spent to retrofit the city's older buildings and bridges. Entire neighborhoods of the city such as the Marina and Hunters Point were created and sit on man made landfill (made up of mud, sand, and rubble from past earthquakes) and other reclamation projects over the San Francisco Bay when flatland became scarce. Such land is extremely unstable during earthquakes; the resultant liquefaction during earthquakes causes extensive damage to property built upon it, as was evidenced in the Marina district during the 1989 Loma Prieta Earthquake. The most impressive example of an "infill neighborhood" is Treasure Island. It was constructed from material dredged from the bay as well as material resulting from tunnelling through Yerba Buena Island in the construction of the Bay Bridge. It was a site for the 1939 San Francisco World's Fair, and it was originally envisioned that Treasure Island would serve as the site for San Francisco's municipal airport, but it became a Navy base at the start of World War II. In 1997 Treasure Island was returned to the city and it provides a unique vantage point to view the San Francisco skyline. San Francisco is famous for its hills. A "Hill" in San Francisco, is an elevation that is over 100 ft (30 Meters). There are a total of 42 hills within city limits. Some of these hills are neighborhoods such as Nob Hill, Pacific Heights, Russian Hill, and Telegraph Hill, while some of these hills are public parks and open space such as Twin Peaks, Mt. Sutro, Mount Davidson, and Buena Vista Park. Near the geographic center of the city and away from the downtown area are a series of less populated hills. Dominating this area is Mount Sutro, which is the site of Sutro Tower, a large red and white radio transmission tower, that is a well known landmark to city residents. Nearby are the equally well known Twin Peaks, which are a pair of hills resting at one of the city's highest points. About 1.2km (1 mile) south of Mount Sutro is San Francisco's highest mountain, Mount Davidson, which is over 282 meters (over 925 feet) high. On top of Mount Davidson is a 31.4 meter (103 foot) tall cross built in 1934. Twin Peaks Not to be missed are the beautiful homes and area of the city known as Pacific Heights as well as victorians in the Haight-Ashbury and the "painted ladies" of Alamo Square and the Castro. San Francisco is also famous for its Cable cars (narrow gauge, 1067 mm (3'6")), which were designed to carry residents up those steep hills. It is still possible to take a cable car ride up and down Nob and Russian Hills. Along with New Orleans' streetcars, San Francisco's cable cars are one of only two mobile United States National Monuments. Coit Tower, a notable landmark dedicated to San Francisco's firefighters, is located at the top of Telegraph Hill.
Climate
Surrounded on three sides by water, San Francisco's climate is strongly influenced by the cool currents of the Pacific Ocean. The weather is remarkably mild all year round, with a so-called Mediterranean climate characterized by cool, foggy summers and relatively warm winters; average daily high temperatures in the summer typically range from the upper 60's to mid 70's (15-22 degrees Celsius), while in the winter it virtually never reaches freezing. Rain in the summer is quite rare, but winters are very rainy. Snow is very rare. The Pacific Ocean off the west coast of the city is particularly cold year round. The combination of cold ocean water and the high heat of the California mainland creates the city's characteristic foggy weather that covers the western half of the city in fog all day during the summer and early fall, as well as the rest of the San Francisco metropolitan area as far as 35-50 miles inland in overcast and fog. Thus, the summer temperatures are significantly lower in San Francisco than in other parts of inland California. The fog is less pronounced during the months of September & October and during the late spring, which is generally the warmest, most summer-like months of the year. In January, morning lows average 46 °F (8 °C) and afternoon highs average 58 °F (14 °C). In August, lows average 56 °F (13 °C) and highs average 72 °F (22 °C). San Francisco receives an average of 22.28 inches (56.6 cm) of precipitation annually with July and August being almost completely free of precipitation. According to the United States Census Bureau, the city and county has a total area of 600.7 km² (231.9 mi²). 120.9 km² (46.7 mi²) of it is land and 479.7 km² (185.2 mi²) of it is water. The total area is 79.86% water. The city proper is often reputed to be roughly a seven mile square, and in fact is only slightly smaller. The geographical center of the city is on the east side of Grandview Avenue between Alvarado and Twenty-third Streets. mi²
Neighborhoods in San Francisco
mi² San Francisco has a Japantown and Chinatown; both are among the largest and oldest in the US. It also boasts a budding Vietnamese community in the Tenderloin neighborhood, Filipinos in Crocker-Amazon and South of Market, an Italian community in North Beach, a French Quarter, and Irish and Russian communities in the Richmond District. The predominantly Hispanic Mission District is the oldest neighborhood in the city, being the site of Mission Dolores, established in 1776. Russian Hill is a residential neighborhood most famous for Lombard Street "the crookedest street in the world". Haight-Ashbury gained prominence during the "Summer of Love" 1960s for its counter-culture and concentration of hippies. The Castro neighborhood has the world's highest concentration of homosexuals. In addition to the predominantly gay Castro, there are significant concentrations of gays in NoeValley, Diamond Heights, Bernal Heights, Potrero Hill, Haight-Ashbury, Hayes Valley, and SOMA. (See The Castro for more gay demographics.) The Castro") at Alamo Square]] Current demographic and land use expansion is concentrated in the east and south. The South of Market neighborhood was an epicenter of the dot-com boom of the late 1990s. A new neighborhood, Mission Bay, is being redeveloped from an industrial area at the far eastern end of South of Market. The cornerstones of this development are the SBC Park baseball stadium and an extension of the University of California, San Francisco medical school.
Parks
The best-known, as well as biggest, park is Golden Gate Park which is 174 acres larger than New York's Central Park. Another notable park is The Presidio at the south edge of the Golden Gate. The Presidio is part of the Golden Gate National Recreation Area, which includes Alcatraz, and many other large local parks. Buena Vista Park located in the Haight-Ashbury, is the city's oldest, established in 1867, nearby Alamo Square is famous for its views of the city and the famous Victorian houses known as the Painted Ladies. A large fresh-water lake, Lake Merced, is located in the south west corner of the city near San Francisco State University and Fort Funston. San Francisco also contains many public beaches such as Baker Beach and Ocean Beach.
Demographics
Ocean Beach, Richmond District, and in Chinatown.]] As of the census of 2000, there are 776,733 people, 329,700 households, and 145,068 families residing in the city. The population density is 6,423.2/km² (16,634.4/mi²), making it the second densest city of 500,000 or more, as well as the fifth densest county, in the country [http://gislounge.com/features/aa041101c.shtml]. . There are 346,527 housing units at an average density of 2,865.6/km² (7,421.2/mi²). The racial makeup of the city is 49.66% White, 7.79% African American, 0.45% Native American, 30.84% Asian, 0.49% Pacific Islander, 6.48% from other races, and 4.28% from two or more races. 14.10% of the population are Hispanic or Latino of any race. The ethnic makeup is 19.6% Chinese, 8.8% Irish, 7.7% German, and 6.1% English. San Francisco has the largest Chinese population in America and the largest Asian population outside of Hawaii. The City has the highest percentage of gay families (as well as a large numbers of single gay people) of any American county or large city. Gay men outnumber lesbians, who are more concentrated in the suburban East Bay. There are 329,700 households out of which 16.6% have children under the age of 18 living with them, 31.6% are married couples living together, 8.9% have a female head of household with no husband present, and 56.0% are non-families. 38.6% of all households are made up of individuals and 9.8% have someone living alone who is 65 years of age or older. The average household size is 2.30 and the average family size is 3.22. In the city the population is spread out with 14.5% under the age of 18, 9.1% from 18 to 24, 40.5% from 25 to 44, 22.3% from 45 to 64, and 13.7% who are 65 years of age or older. The median age is 36 years. For every 100 females there are 103.4 males. For every 100 females age 18 and over, there are 103.1 males. The median income for a household in the city is $55,221, and the median income for a family is $63,545 one of the highest in the United States at 15th place overall and 3rd in a single large city. Males have a median income of $46,260 versus $40,049 for females. The per capita income for the city is $34,556 which is ranked as the 19th highest in the country. 11.3% of the population and 7.8% of families are below the poverty line. Out of the total population, 13.5% of those under the age of 18 and 10.5% of those 65 and older are living below the poverty line.
Government and politics
As the official name implies, the City and County San Francisco is a metropolitan municipality, being simultaneously a charter city and charter county with a consolidated government. It is the only metropolitan municipality in California and the only California county with a mayor, who is also the county executive. San Francisco is the only California city with a board of supervisors, which is also the city council. San Francisco's unique status also makes it a municipal corporation and an administrative division of the state. It is in the latter capacity that San Francisco exercises jurisdiction over property that would otherwise be located outside of its corporation limit. San Francisco International Airport, for example, would be located within San Mateo County but for the fact it is owned and operated by the City and County of San Francisco. Because counties are administrative divisions of the state, it is legally impossible for two counties to occupy or exercise jurisdiction over the same piece of land. Thus, the airport, which is about 15 miles south of mainland San Francisco, is legally part of San Francisco because the municipality owns it. San Francisco exercises jurisdiction over the Hetch Hetchy Valley and watershed, in Yosemite National Park, pursuant to a perpetual leasehold granted by Act of Congress in 1913, the Raker Act. Under the current charter, the Government of San Francisco is constituted of two co-equal branches - the executive or administrative branch, which is headed by the mayor and includes other city-wide elected and appointed officials, and the civil service; and the legislative branch, which is constituted of the San Francisco Board of Supervisors, which exercises general oversight over all city and county functions. The mayor is elected every four years, in the odd-numbered year that precedes the U.S. presidential election. The current mayor, Gavin Newsom, was elected in December 2003 in a runoff competition against Matt Gonzalez (see also List of Mayors of San Francisco, California). Gonzalez was president of the Board of Supervisors, representing District 5, and Newsom was a member of the board representing District 2. If the mayor dies or resigns, the President of the Board of Supervisors assumes the office until a special election can be held. The eleven members of the Board of Supervisors (as of January 2005) are listed in the table at right by district number[http://www.sfgov.org/site/bdsupvrs_index.asp?id=4385]. The current president of the Board is Aaron Peskin, who represents District 3. How the Board of Supervisors shall be elected has been a bone of contention in recent San Francisco history. Throughout the United States, almost all cities and counties with populations in excess of 20,000 divide the jurisdiction into electoral districts (in cities, often called "wards") to ensure proportionate representation of the whole community and to evenly distribute the community interaction workload evenly among the members of the governing body (city council, county board of supervisors, etc.) But California has always been disinclined to follow examples set by the rest of the country; and San Francisco, notwithstanding a population of 0.7 million, has been no exception. Prior to 1977 and again from 1980 through 2000, the San Francisco Board of Supervisors was elected at-large. All candidates appeared together on the ballot. The person who received the most votes was elected President of the Board of Supervisors, and the next ten were elected to seats on the board. The first district-based elections in 1977 resulted in a radical change to the composition of the Board, including the election of Harvey Milk, only the third openly gay or lesbian individual (and the first who was male) elected to public office in the United States. Following the assassinations of Supervisor Milk and Mayor George Moscone a year later, by Supervisor Dan White who had just resigned, district elections were deemed divisive and San Francisco returned to at-large elections until the current system was implemented in 2000. Under the current system, Supervisors are elected by district to four-year terms. The terms are staggered so that only half the board is elected every two years, thereby providing continuity. Supervisors representing odd-numbered districts (1, 3, 5, 7, 9, and 11) are elected every fourth year counted from 2000 (so, 2000, 2004, 2008, etc.). Supervisors representing even-numbered districts (2, 4, 6, 8, and 10) were elected to transitional two-year terms in 2000, thereafter to be elected every fourth year (2002, 2006, 2010, etc.). The President of the Board of Supervisors, under the new system, is elected by the members of the Board from among their number. This is done by secret ballot, typically at the first meeting of the new session commencing after the general election. The Mayor and members of the Board of Supervisors are subject to term limits under the San Francisco Charter. None may serve more than two consecutive terms. As part of the change to district elections, however, this provision applies to supervisors only as of the first full term of election following its implementation in 2000. Thus, Tom Ammiano, who was elected to the Board of Supervisors in 1994 and 1998 under the old system, then again in 2000 under the new system, was able to run yet again in 2004 (and won). A single vote transfer system of elections was approved by the electorate and implemented in time for the 2004 general election. This system replaced the old, expensive system of run-off elections. Under this new ranked-choice system, whenever there are more than two candidates for an office, voters rank their choices in order of preference. If a candidate does not achieve a majority of votes cast when the first choice votes are counted, the candidate with the least number of votes is eliminated and the second choice votes on those ballots are tabulated and "transferred" to the remaining candidates. The process continues, as necessary, until one candidate achieves a majority of votes cast and is then declared the winner. Eyed warily by some and optimistically by others - in both cases owing to the belief that single-transfer voting might favour so-called "progressive" and "minority party" candidates over so-called "conservative" and "mainstream party" candidates - the 2004 general election results showed that belief to be unfounded, as all incumbent Supervisors were returned to office. Vacancies on the Board of Supervisors are filled by mayoral appointment, subject to special election (except as the Charter permits an appointee to remain in office until the general election for the seat is held). A person appointed or elected to fill a vacancy of less than two years is not deemed to have served a full term for purposes of term limits, whereas a person who fills a vacancy with more than two years remaining in the term is deemed to serve a full term and will be able to run for a consecutive term only once. The Mayor's 2005-2006 proposed budget forecasts general fund expenditures of $2.44 billion. As the largest city on the west coast before World War I, San Francisco became and remains the legal hub for the western United States. The Ninth Circuit U.S. Court of Appeals and the Federal District Court for Northern California are headquartered in San Francisco. The Supreme Court of California is also headquartered in San Francisco, making The City the de facto judicial capital of the state. California is the only U.S. jurisdiction whose highest court and judicial seat is not in the official state or territorial capital. The California Supreme Court also maintains branch offices in Los Angeles and Sacramento. In addition, the city is the seat of the First Appellate District of the State Courts of Appeals and the San Francisco County Superior Court.
City flag
The flag depicts a rising Phoenix, symbolic of the City's recovery from the 1906 fire. Underneath the phoenix it has a motto written in Spanish: "Oro en Paz, Fierro en Guerra," which translates into: "Gold in Peace, Iron in War."
City seal
The seal, which was adopted in the 1850s, depicts two working men, on one side a miner and on the other a sailor with a sextant. Above is a rising phoenix and behind is the bay with sailing ships. The Phoenix symbolizes the city's emergence from the ashes of several devastating fires in the early 1850's.
Economy
Because of the California gold rush, San Francisco became and remains the banking and financial center of the U.S. West Coast. It is the home of the twelfth district of the U.S. Federal Reserve as well as major production facilities for the U.S. Mint. The Pacific Exchange is located in the financial district. Many major American and international banks and venture capital firms have all set up their regional headquarters in the city. Fortune 500 rankings indicated in parenthesis. Companies headquartered in San Francisco are: Companies headquartered near San Francisco include:
Education
The city is served by San Francisco Unified School District. Despite its limited geographical space, San Francisco is home to a multitude of Universities and Colleges. Public universities include:
- University of California, San Francisco, primarily a Medical School, located north of Forest Hill
- San Francisco State University located in the southwest corner of the city near Lake Merced
- University of California, Hastings College of the Law located downtown at its Civic Center
- City College of San Francisco, one of the largest community colleges in the country is located in the Ingleside, with several extension campuses. Private universities:
- The Jesuit-run University of San Francisco, one of the first universities established west of the Mississippi, located in the center of the city
- Golden Gate University, a business and law school located downtown
-

Amplitude modulation
Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. (Contrast this with frequency modulation, in which the frequency of the carrier is varied; and phase modulation, in which the phase is varied.) AM is commonly used at radio frequencies and was the first method used to broadcast commercial radio. The term "AM" is sometimes used generically to refer to the AM broadcast (mediumwave) band (see AM radio).
Applications in radio
AM radio A basic AM radio transmitter works by first DC-shifting the modulating signal, then multiplying it with the carrier wave using a frequency mixer. The output of this process is a signal with the same frequency as the carrier but with peaks and troughs that vary in proportion to the strength of the modulating signal. This is amplified and fed to an antenna. An AM receiver consists primarily of a tunable filter and an envelope detector, which in simpler sets is a single diode. Its output is a signal at the carrier frequency, with peaks that trace the amplitude of the unmodulated signal. Unlike other modulation techniques, this is all that is needed to recover the original audio. In practice, a capacitor is used to undo the DC shift introduced by the transmitter and to eliminate the carrier frequency by connecting the signal peaks. The output is then fed to an audio amplifier. The fact that signals can be decoded using very simple equipment is one of the primary advantages of amplitude modulation. This was especially important in the early days of commercial radio, when electronic components were still quite expensive. This simplicity and affordability helped make AM one of the most popular methods for sending voice and music over radio during the 20th century. the 20th century, with the recovered audio fed directly to an earphone.]] AM radio's main limitation is its susceptibility to atmospheric interference, which is heard as static from the receiver. The narrow bandwidth traditionally used for AM broadcasts further limits the quality of sound that can be received. Since the 1970s wideband FM has been preferred for musical broadcasts, due to its higher audio fidelity and noise-suppression characteristics.
Forms of AM
In its basic form, amplitude modulation produces a signal with power concentrated at the carrier frequency and in two adjacent sidebands. Each sideband is equal in bandwidth to that of the modulating signal and is a mirror image of the other. Thus, most of the power output by an AM transmitter is effectively wasted: half the power is concentrated at the carrier frequency, which carries no useful information (beyond the fact that a signal is present); the remaining power is split between two identical sidebands, only one of which is needed. To increase transmitter efficiency, the carrier can be removed (suppressed) from the AM signal. This produces a reduced-carrier transmission or double-sideband suppressed carrier (DSSC) signal. If the carrier is only partially suppressed, a double-sideband reduced carrier (DSRC) signal results. DSSC and DSRC signals need their carrier to be regenerated (by a beat frequency oscillator, for instance) to be demodulated using conventional techniques. Even greater efficiency is achieved—at the expense of increased transmitter and receiver complexity—by completely suppressing both the carrier and one of the sidebands. This is single-sideband modulation, widely used in amateur radio due to its efficient use of both power and bandwidth. A simple form of AM often used for digital communications is on-off keying, a type of amplitude-shift keying by which binary data is represented as the presence or absence of a carrier wave. This is commonly used at radio frequencies to transmit Morse code, referred to as continuous wave (CW) operation.
Example
Suppose we wish to modulate a simple sine wave on a carrier wave. The equation for the carrier wave of frequency $\omega_c$ , taking its phase to be a reference phase of zero, is : $c(t) = C \sin(\omega_c t)$ . The equation for the simple sine wave of frequency $\omega_m$ (the signal we wish to broadcast) is : $m(t) = M \sin(\omega_m t + \phi)$ , with $\phi$ its phase offset relative to $c(t)$ . Amplitude modulation is performed simply by adding $m(t)$ to $C$ . The amplitude-modulated signal is then : $y(t) = (C + M \sin(\omega_m t + \phi)) \sin(\omega_c t)$ The formula for $y(t)$ above may be written : $y(t) = C \sin(\omega_c t) + M \frac - M \frac$ The broadcast signal consists of the carrier wave plus two sinusoidal waves each with a frequency slightly different from $\omega_c$ , known as sidebands. For the sinusoidal signals used here, these are at $\omega_c + \omega_m$ and $\omega_c - \omega_m$ . As long as the broadcast (carrier wave) frequencies are sufficiently spaced out so that these side bands do not overlap, stations will not interfere with one another.
A more general example
:This relies on knowledge of the Fourier Transform. The discussion of the figure may prove more useful for a quicker understanding. Consider a general modulating signal $m(t)$ , which can now be anything at all. The same basic rules apply: : $\,y(t) = [C + m(t)]\cos(\omega_c t)$ . Or, in complex form: : $y(t) = [C + m(t)]\frac$ Taking Fourier Transforms, we get: : $|Y(\omega)| = \piC\delta(\omega - \omega_c) + \fracM(\omega - \omega_c) + \piC\delta(\omega + \omega_c) + \fracM(\omega + \omega_c)$ , where $\delta(x)$ is the Dirac delta function — a unit impulse at $x$ — and capital functions indicate Fourier Transforms. This has two components: one at positive frequencies (centered on $+\omega_c$ ) and one at negative frequencies (centered on $-\omega_c$ ). There is nothing mathematically wrong with negative frequencies, and they need to be considered here — otherwise one of the sidebands will be missing. Shown below is a graphical representation of the above equation. It shows the modulating signal's spectrum on top, followed by the full spectrum of the modulated signal. spectrum This makes clear the two sidebands that this modulation method yields, as well as the carrier signals that go with them. The carrier signals are the impulses. Clearly, an AM signal's spectrum consists of its original (2-sided) spectrum shifted up to the carrier frequency. The negative frequencies are a mathematical nicety, but are essential since otherwise we would be missing the lower sideband in the original spectrum! As already mentioned, if multiple signals are to be transmitted in this way (by frequency division multiplexing), then their carrier signals must be sufficiently separated that their spectra do not overlap. This analysis also shows that the transmission bandwidth of AM is twice the signal's original (baseband) bandwidth — since both the positive and negative sidebands are 'copied' up to the carrier frequency, but only the positive sideband is present originally. Thus, double-sideband AM is spectrally inefficient. The various suppression methods in Forms of AM, can be seen clearly in the figure — with the carrier suppressed there will be no impulses and with a sideband suppressed, the transmission bandwidth is reduced back to the original, baseband, bandwidth — a significant improvement in spectrum usage. An analysis of the power consumption of AM reveals that DS-AM with its carrier has an efficiency of about 33% — very poor. The forms of AM with suppressed carriers are found to be 100% power efficient, since no power is wasted on the carrier signal which conveys no information.
Modulation index
As with other modulation indices, in AM, this quantity indicates by how much the modulated variable varies around its 'original' level. For AM, it relates to the variations in the carrier amplitude and is defined as: : $h = \frac$ . So if $h=0.5$ , the carrier amplitude varies by 50% above and below its unmodulated level, and for $h=1.0$ it varies by 100%.
See also

- AM radio
- Mediumwave
- Modulation, for a list of other modulation techniques
References

- Newkirk, David and Karlquist, Rick (2004). Mixers, modulators and demodulators. In D. G. Reed (ed.), The ARRL Handbook for Radio Communications (81st ed.), pp. 15.1–15.36. Newington: ARRL. ISBN 0-87259-196-4. Category:Radio modulation modes ko:진폭 변조 ja:振幅変調

KNEW-TV

KQEC-TV, Channel 32 in San Francisco, California, was a member station of the Public Broadcasting System (PBS). The station began in 1954 with an erratic broadcast history as commercial KSAN-TV. Its next owner, Metromedia returned it to the air on June 17, 1968 as independent KNEW-TV. 1968 was a year that had been fruitful for San Francisco Bay Area television broadcasting: KBHK, channel 44, KEMO, (now today's KBWB) channel 20 and KUDO, channel 38 (now KCNS), all started in that year. In 1970 Metromedia donated KNEW-TV to non-commercial KQED, one of the first public television stations in the United States, becoming sister station KQEC. The KQED organization gave up its FCC license to KQEC in 1991. The broadcasting slot of channel 32 in San Francisco was granted to the Minority Television Project, which adopted the call letters "KMTP." Category:PBS member stations

KMTP-TV

KMTP, the San Francisco non-commercial station operated by the Minority Television Project, airs programming in several non-English Asian languages, and in German. It also broadcasts the English language programming of Deutsche-Welle TV (DWTV) and the Classic Arts Showcase. The station on channel 32 began commercially as one of the first UHF TV stations in the United States in 1958 as KSAN-TV, owned by the Patterson family, operators of KSAN(AM) radio, showing an amalgam of boxing and wrestling matches, medical conferences, and old movies. The TV station was purchased by Metropolitan Television (aka Metromedia) in 1966, when the callsign was moved to an FM station and the station re-christened KNEW-TV, to match its co-owned KNEW AM station. KNEW-TV ran the syndicated Metromedia talkshows and variety programming of such stars as shock-talker Joe Pyne, Merv Griffin, and others. This format was unsuccessful, and by 1969 channel 32 was given to leading public broadcaster KQED and re-christened once again, this time as KQEC. KQED held onto it until 1991 when the FCC ruled that it had been off the air too much to remain in the hands of the KQED ownership. KQED gave the station to Minority Television Project, one of the challengers of the KQEC license.

External links

- [http://www.kmtp.org KMTP Homepage]
-

KIOI (FM)

KIOI FM ("Star 101.3") is a radio station which has San Francisco as its city of license. Originally founded as KLX-FM by the Oakland Tribune newspaper, the station was sold in 1958 to radio engineers, James Gabbert, Gary Geilow, and newscaster Jerry Jensen, when it was moved to the San Francisco Peninsula and became KPEN. As KPEN, the station became the first FM stereo broadcaster in California (and the third in the country), raised its effective radiated power to 120,000 watts, and went after an adult demographic. In 1980, in an effort to link the dial position of 101.3 with the callsign, the station changed its callsign to KIOI-FM in order to look like its K101 moniker, ushering in today's common practice of calling stations by dial positions and slogans rather than strictly by callsigns. Also in that year, KIOI got away from block music programming and changed its format to a more contemporary sound. For years, KIOI was one of the highest-billing and most-listened to FM radio stations in the San Francisco Bay Area. KIOI dropped the -FM suffix in 1984, and is now owned by Clear Channel Communications. Its current 125kW power is grandfathered-in, as the FCC no longer allows FM stations over 50kW in the region, or 100kW anywhere. KIOI FM has two booster stations: KIOI-FM1 in Walnut Creek since 1989, and KIOI-FM2 in Pleasanton since 1998.

External links

-
- [http://www.star1013fm.com Star 101.3 official site] Category:Clear Channel radio stations IOI

Frequency modulation

Frequency modulation (FM) is a form of modulation which represents information as variations in the instantaneous frequency of a carrier wave. (Contrast this with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant.) In analog applications, the carrier frequency is varied in direct proportion to changes in the amplitude of an input signal. Digital data can be represented by shifting the carrier frequency among a set of discrete values, a technique known as frequency-shift keying. FM is commonly used at VHF radio frequencies for high-fidelity broadcasts of music and speech (see FM broadcasting). Normal (analog) TV sound is also broadcast using FM. A narrowband form is used for voice communications in commercial and amateur radio settings. The type of FM used in broadcast is generally called wide-FM, or W-FM. In two-way radio, narrowband narrow-fm (N-FM) is used to conserve bandwidth. In addition, it is used to send signals into space. FM is also used at intermediate frequencies by most analog VCR systems, including VHS, to record the luminance (black and white) portion of the video signal. FM is the only feasible method of recording to and retrieving from magnetic tape without extreme distortion, as video signals have a very large range of frequency components -- from a few hertz to several megahertz. FM is also used at audio frequencies to synthesize sound. This technique, known as FM synthesis, was popularized by early digital synthesizers and became a standard feature for several generations of personal computer sound cards.

Applications in radio

sound card Edwin Armstrong presented his paper: [https://michael.industrynumbers.com/fm.pdf "A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation"], which first described FM radio, before the New York section of the Institute of Radio Engineers on November 6, 1935. Frequency modulation requires a wider bandwidth than amplitude modulation by an equivalent modulating signal, but this also makes the signal more robust against interference. Frequency modulation is also more robust against simple signal amplitude fading phenomena. As a result, FM was chosen as the modulation standard for high frequency, high fidelity radio transmission: hence the term "FM radio" (although for many years the BBC insisted on calling it "VHF radio", which is quite logical, since commercial FM broadcasting uses a well-known part of the VHF band; in certain countries, expressions referencing the more familiar wavelength notion are still used in place of the somewhat mysterious modulation technique name). FM receivers inherently exhibit a phenomenon called capture, where the tuner is able to clearly receive the stronger of two stations being broadcast on the same frequency. Problematically, however, frequency drift or lack of selectivity may cause one station or signal to be suddenly overtaken by another on an adjacent channel. Frequency drift typically constituted a problem on very old or inexpensive receivers, while inadequate selectivity may plague any tuner. An FM signal can also be used to carry a stereo signal: see FM stereo. However, this is done by using multiplexing and demultiplexing before and after the FM process, and is not part of FM proper. The rest of this article ignores the stereo multiplexing and demultiplexing process used in "stereo FM", and concentrates on the FM modulation and demodulation process, which is identical in stereo and mono processes.

Theory

If the signal to be transmitted is :

x_m(t)\,

which is restricted in amplitude to be :

\left| x_m(t) \right| \le 1 \,

and the sinusoidal carrier is :

x_c(t) = A \cos (2 \pi f_c t)\,

where f_c is the carrier's base frequency in hertz and A is an arbitrary amplitude, the carrier will be modulated by the signal as in :

x_c(t) = A \cos \left( 2 \pi \int_^ f(\tau)\, d \tau \right) = A \cos \left( 2 \pi \int_^ \left[ f_c + f_\Delta x_m(\tau) \right] \, d \tau \right)

:where,

f(t) = f_c + f_\Delta x_m(t)

In this equation, f(t) is the instantaneous frequency of the oscillator and f_Δ is the frequency deviation, which represents the maximum shift away from f_c in one direction, assuming x_m(t) is limited to the range ±1. Although it may seem that this limits the frequencies in use to f_c ± f_Δ, this neglects the distinction between instantaneous frequency and spectral frequency. The frequency spectrum of an actual FM signal has components extending out to infinite frequency, although they become negligibly small beyond a point. For a simplified case, the harmonic distribution of a sine wave signal modulated by another sine wave signal can be represented with Bessel functions - this provides a basis for a mathematical understanding of frequency modulation in the frequency domain. A rule of thumb, Carson's rule states that nearly all the power of a frequency modulated signal lies within a bandwidth of :

2(f_\Delta +f_m)\,

where f_Δ is the peak deviation of the instantaneous frequency f(t) from the center carrier frequency f_c (assuming x_m(t) is in the range ±1) and f_m is the highest modulating frequency of x_m(t). Note that frequency modulation can be regarded as a special case of phase modulation where the carrier phase modulation is the time integral of the FM modulating signal. Frequency-shift keying refers to the simple case of frequency modulation by a simple signal with only discrete states, such as in Morse code or radio-teletype applications. Manchester encoding may be regarded as a simple version of frequency shift keying, where the high and low frequencies are respectively double and the same as the bit rate, and the bit transitions are synchronous with carrier transitions. When used in supervisory signaling in telephony, the term frequency-change signaling has been used to describe frequency modulation. The phrase frequency-modulated, an adjective, should have a hyphen when used attributively.

Modulation Index

As with other modulation indices, in AM this quantity indicates by how much the modulated variable varies around its unmodulated level. For FM, it relates to the variations in the frequency of the carrier signal: :

h = \frac = \frac \

With a tone-modulated FM wave, if the modulation frequency is held constant and the modulation index is increased, the (non-negligible) bandwidth of the FM signal increases, but the spacing between spectra stays the same. If the frequency deviation is held constant and the modulation index increased, the bandwidth stays roughly the same, but the spacing between spectra decreases.

External links

- http://www.rfcafe.com/references/electrical/frequency_modulation.htm
- http://www.fas.org/man/dod-101/navy/docs/es310/FM.htm Category:Radio modulation modes ko:주파수 변조 ja:周波数変調

ICAO airport code

The ICAO airport code is a four-letter alphanumeric code designating each airport around the world. These codes are defined by the International Civil Aviation Organization. The ICAO codes are used by air traffic control and airline operations such as flight planning. They are not the same as the IATA codes encountered by the general public, which are used for airline timetables, reservations, and baggage handling. ICAO codes are also used to identify weather stations, whether or not they are located at airports. Unlike the IATA codes, the ICAO codes have a regional structure. In general, the first letter is allocated by continent and represents a country or group of countries within that continent. The second letter generally represents a country within that region, and the remaining two are used to identify each airport. The exception to this rule are larger countries that have single-letter country codes, where the remaining three letters identify the airport. In the United States and Canada, most airports which have been assigned three-letter IATA codes use the same code with leading "K" or "C" as their ICAO code (or P, in the case of Alaska and Hawaii); e.g., YYC (Calgary International Airport, Calgary, Alberta) and CYYC, IAD (Dulles International Airport, Chantilly, Virginia) and KIAD. These codes are not to be confused with radio call signs, even though both countries use four-letter callsigns starting with those letters. A list of airports, sorted by IATA code, is available.

Prefixes

AG = Solomon Islands AN = Nauru AY = Papua New Guinea BG = Greenland BI = Iceland C = Canada DA = Algeria DB = Benin DF = Burkina Faso DG = Ghana DI = Côte d'Ivoire DN = Nigeria DR = Niger DT = Tunisia DX = Togolese Republic EB = Belgium ED = Germany (Civil) EE = Estonia EF = Finland EG = United Kingdom of Great Britain and Northern Ireland EH = Netherlands EI = Ireland EK = Denmark EL = Luxembourg EN = Norway EP = Poland ES = Sweden ET = Germany (Military) EV = Latvia EY = Lithuania FA = South Africa FB = Botswana FC = Republic of the Congo FD = Swaziland FE = Central African Republic FG = Equatorial Guinea FH = Ascension Island FI = Mauritius FJ = British Indian Ocean Territory FK = Cameroon FL = Zambia FM = Comoros, Madagascar, Mayotte, Réunion FN = Angola FO = Gabon FP = São Tomé and Príncipe FQ = Mozambique FS = Seychelles FT = Chad FV = Zimbabwe FW = Malawi FX = Lesotho FY = Namibia FZ = Democratic Republic of the Congo GA = Mali GB = The Gambia GC = Canary Islands (Spain) GE = Ceuta and Melilla (Spain) GF = Sierra Leone GG = Guinea-Bissau GL = Liberia GM = Morocco GO = Senegal GQ = Mauritania GS = Western Sahara GU = Guinea GV = Cape Verde HA = Ethiopia HB = Burundi HC = Somalia HD = Djibouti (also HF) HE = Egypt HH = Eritrea HK = Kenya HL = Libya HR = Rwanda HS = Sudan HT = Tanzania HU = Uganda K = United States of America (Continental) LA = Albania LB = Bulgaria LC = Cyprus LD = Croatia LE = Spain LF = France (including Saint-Pierre and Miquelon) LG = Greece LH = Hungary LI = Italy LJ = Slovenia LK = Czech Republic LL = Israel LM = Malta LN = Monaco LO = Austria LP = Portugal (includes Azores) LQ = Bosnia and Herzegovina LR = Romania LS = Switzerland LT = Turkey LU = Moldova LV = Gaza Strip LW = Macedonia LX = Gibraltar LY = Serbia and Montenegro LZ = Slovakia MB = Turks and Caicos Islands MD = Dominican Republic MG = Guatemala MH = Honduras MK = Jamaica MM = Mexico MN = Nicaragua MP = Panama MR = Costa Rica MS = El Salvador MT = Haiti MU = Cuba MW = Cayman Islands MY = Bahamas MZ = Belize NC = Cook Islands NF = Fiji, Tonga NG = Kiribati (Gilbert Islands), Tuvalu NI = Niue NL = Wallis and Futuna NS = Samoa NT = French Polynesia NV = Vanuatu NW = New Caledonia NZ = New Zealand OA = Afghanistan OB = Bahrain OE = Saudi Arabia OI = Iran OJ = Jordan and the West Bank OK = Kuwait OL = Lebanon OM = United Arab Emirates OO = Oman OP = Pakistan OR = Iraq OS = Syria OT = Qatar OY = Yemen PA = United States of America (Alaska) PB = Baker Island PC = Kiribati (Canton Airfield, Phoenix Islands) PF = Fort Yukon, Alaska PG = Guam, Northern Marianas PH = United States of America (Hawaii) PJ = Johnston Atoll PK = Marshall Islands PL = Kiribati (Line Islands) PM = Midway Island PO = Oliktok Long Range Radar Station, Alaska PP = Point Lay, Alaska PT = Federated States of Micronesia, Palau PW = Wake Island RC = Taiwan RJ = Japan (most of country) RK = South Korea RO = Japan (Okinawa Prefecture and Yoron) RP = Philippines SA = Argentina SB = Brazil (also SD, SN, SS, and SW) SC = Chile SE = Ecuador SF = Falkland Islands SG = Paraguay SK = Colombia SL = Bolivia SM = Suriname SO = French Guiana SP = Peru SU = Uruguay SV = Venezuela SY = Guyana TA = Antigua and Barbuda TB = Barbados TD = Dominica TF = Guadeloupe TG = Grenada TI = U.S. Virgin Islands TJ = Puerto Rico TK = Saint Kitts and Nevis TL = Saint Lucia TN = Netherlands Antilles, Aruba TQ = Anguilla TR = Montserrat TT = Trinidad and Tobago TU = British Virgin Islands TV = Saint Vincent and the Grenadines TX = Bermuda U = Russia (except UA, UB, UG, UK, UM and UT) UA = Kazakhstan, Kyrgyzstan UB = Azerbaijan UG = Armenia, Georgia UK = Ukraine UM = Belarus UT = Tajikistan, Turkmenistan, Uzbekistan VA = India (also VE, VI, and VO) VC = Sri Lanka VD = Cambodia VE = India (also VA, VI, and VO) VG = Bangladesh VH = Hong Kong VI = India (also VA, VE, and VO) VL = Laos VM = Macao VN = Nepal VO = India (also VA, VE, and VI) VQ = Bhutan VR = Maldives VT = Thailand VV = Vietnam VY = Myanmar WA = Indonesia (also WI, WQ, and WR) WB = Malaysia (also WM), Brunei WI = Indonesia (also WA, WQ, and WR) WM = Malaysia (also WB) WP = Timor-Leste WQ = Indonesia (also WA, WI, and WR) WR = Indonesia (also WA, WI, and WQ) WS = Singapore Y = Australia Z = People's Republic of China (except ZK and ZM) ZK = North Korea ZM = Mongolia

Some examples

References

- [http://www.homepages.mcb.net/bones/06airfields/icao.htm ICAO World Airfield Catalogue]
- [http://www8.landings.com/cgi-bin/get_file?APT/icao_prefix.html ICAO airport code prefixes]
- [http://www.faa.gov/ATPUBS/LID/LIDHME.htm IATA location identifiers] Category:Geocodes ja:空港コード

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