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Charles Osgood

Charles Osgood

Charles Osgood (born January 8, 1933) is a radio and television commentator in the United States. His daily program, The Osgood File, has been broadcast on the CBS Radio Network since 1971. Osgood was born in New York. He graduated from Fordham University with a Bachelor of Science degree in 1954 with a major in economics. He was inducted into the Radio Hall of Fame in 1990. Osgood also writes a bi-weekly syndicated newspaper column, and has written four books. On television, Osgood hosts CBS Sunday Morning. He has also anchored the CBS Sunday Night News and the CBS Morning News. Among his personal trademarks are his bow tie and his propensity for delivering his commentaries in verse. In August 1967, he anchored the first morning drive shift for WCBS-AM after its conversion to an all-news format. The twist was that the first day of all-news programming actually aired on WCBS-FM after an airplane crashed into the AM station's transmitter on New York's High Island.

External links


- [http://www.radiohof.org/news/charlesosgood.html Radio Hall of Fame]
- [http://wcbs880.com/osgood/ Charles Osgood page] at WCBS AM web site Osgood, Charles

1933

1933 (MCMXXXIII) was a common year starting on Sunday (link will take you to calendar).

Events

January


- January 3 - Japanese troops occupy Shanghai
- January 5 - Construction of the Golden Gate Bridge begins in San Francisco Bay.
- January 15 - Political violence has caused almost 100 deaths in Spain
- January 17 - US Congress votes favorable for Philippines independence, against the view of president Hoover
- January 30 - Edouard Daladier forms a government in France
- January 30 - Adolf Hitler appointed Chancellor of Germany by Reich President Paul von Hindenburg.
- January 30 - The first airing of episode 1 of 2,956 episodes of the radio program The Lone Ranger.

February


- February 4 - Mutiny starts on the Dutch pantserschip Zeven Provincien.
- February 6 - The 20th Amendment to the United States Constitution goes into effect.
- February 6-7 - Officers on the USS Ramapo record 34 meters high sea-wave in the Pacific
- February 10 - The New York City-based Postal Telegraph Company introduces the first singing telegram.
- February 15 - In Miami, Florida Giuseppe Zangara attempts to assassinate President-elect Franklin D. Roosevelt, but instead kills Chicago, Illinois Mayor Anton J. Cermak.
- February 17 - The magazine Newsweek is published for the first time.
- February 17 - The Blaine Act ends Prohibition in the United States.
- February 27 - Germany's parliament building in Berlin, the Reichstag, is set on fire (see: Reichstag fire).

March


- March 1 - Kyriakos Varvaressos becomes Deputy Governor to the Bank of Greece
- March 3 - Mount Rushmore is dedicated.
- March 4 - American President Herbert Clark Hoover is succeeded by Franklin Delano Roosevelt, who in reference to the Great Depression, gives his "We have nothing to fear, but fear itself" inauguration speech.
- March 4 Frances Perkins becomes United States Secretary of Labor, first female member of the United States Cabinet.
- March 4 - The Parliament of Austria is suspended because of a quibble over procedure - Chancellor Engelbert Dollfuss initiates authoritarian rule by decree (see Austrofascism)
- March 5 - Great Depression: President Franklin D. Roosevelt declares a "bank holiday", closing all United States banks and freezing all financial transactions (the 'holiday' ended on March 13).
- March 5 - in German elections, National Socialists gain 43.9% of the votes
- March 9 - Great Depression: The U.S. Congress begins its first 100 days of enacting New Deal legislation.
- March 10 - Earthquake in Long Beach, California kills 117 people.
- March 12 - Great Depression: Franklin Delano Roosevelt addresses the nation for the first time as President of the United States. This was also the first of his "Fireside Chats".
- March 20 - Dachau, the first Nazi concentration camp, is completed - opened March 22
- March 23 - The Reichstag passes the Enabling Act, making Adolf Hitler dictator of Germany.
- March 27 - Japan leaves the League of Nations
- March 31 - The Civilian Conservation Corps is established with the mission to relieve rampant unemployment.

April


- April 1 - The recently elected Nazis under Julius Streicher organize a one-day boycott of all Jewish-owned businesses in Germany, ushering in the series of anti-Semitic acts that will be known as the Holocaust.
- April 3 - Anti-monarchist rebellion in Siam
- April 4 - US airship Akron crashes near New York - 74 dead
- April 5 - International court in the Hague decides that Greenland belongs to Denmark and condemns Norwegian landings on eastern Greenland. Norway submits to the decision
- April 11 - Aviator William Lancaster takes off in England in an attempt to make a speed record to Cape. He vanishes (body is found 1962 in Sahara)
- April 21 - Nazi Germany outlaws kosher ritual shechita
- April 23 - Japanese crown prince Akihito born
- April 26 - Gestapo established.
- April 26 - Editors of Harvard Lampoon steal the Sacred Cod of Massachusetts from the State House. It is returned two days later
- April 27 - Stahlhelm organizations joins the Nazi party
- May - Detection by Karl Jansky of radio waves from the centre of the Milky Way galaxy reported

May


- May 2 - First modern sighting of the Loch Ness Monster.
- May 2 - Gleichschaltung: Adolf Hitler bans trade unions.
- May 8 - Mohandas Gandhi begins a 3-week hunger strike because of the mistreatment of the lower castes
- May 10 - Censorship: In Germany, the Nazis stage massive public book burnings.
- May 10 - Paraguay declares war on Bolivia
- May 17 - Vidkun Quisling and Johan Bernhard Hjort form Nasjonal Samling - the national-socialist party of Norway.
- May 18 - New Deal: President Franklin Delano Roosevelt signs an act creating the Tennessee Valley Authority.
- May 26 - Nazi party in Germany introduces law to legalize eugenic sterilization
- May 27 - New Deal: The Federal Securities Act is signed into law requiring the registration of securities with the Federal Trade Commission.
- May 27 - The Century of Progress world's fair opens in Chicago, Illinois.

June


- June 5 - The U.S. Congress abrogates the United States' use of the gold standard by enacting a joint resolution (48 Stat. 112) nullifying the right of creditors to demand payment in gold.
- June 6 - The first drive-in theater opened in Camden New Jersey.
- June 17 - In Kansas City, Missouri, Pretty Boy Floyd kills four unarmed FBI agents and captured fugitive Frank Nash in a failed attempt to free Nash. This becomes known as the Union Station Massacre.
- June 21 - All non-Nazi parties forbidden in Germany
- June 25 - Wilmersdorfer Tennishallen delegate convention in Berlin

July


- July 4 - Mohandas Gandhi sentenced to prison
- July 14 - Forming new political parties forbidden in Germany.
- July 20 - 500.000 people demonstrate against anti-Semitism in Hyde Park, London
- July 22 - Wiley Post becomes first person to fly solo around the world, traveling 15,596 miles in 7 days, 18 hours, and 45 minutes.
- July 22 - "Machine-Gun" Kelly and Albert Bates kidnap Charles Urschel, an Oklahoma oilman, and demand $200.000 ransom

August


- August 14 - Loggers cause a forest fire in the Coast Range of Oregon, later known as the first forest fire of the Tillamook Burn. It is extinguished on September 5, after destroying 240,000 acres (971 km²).
- August 30 - Assassination of Theodore Lessing in Marienbad (Mariánské Lázně), Czechoslovakia
- August 30 - Air France begins operations with 250 planes.

September


- September 3 - Alejandro Lerroux forms a new government in Spain.
- September 12 - Leó Szilárd, waiting for a red light on Southampton Row in Bloomsbury, conceives the idea of the nuclear chain reaction.
- September 26 - Tornado destroys the town of Tampico in Mexico.

October


- October 1 - Failed assassination attempt against Englebert Dolfuss only injures him seriously.
- October 12 - The United States Army Disciplinary Barracks on Alcatraz is acquired by the United States Department of Justice, which plans to incorporate the island into its Bureau of Prisons as a federal penitentiary.
- October 16 - Germany announces intention to leave the League of Nations - officially
- October 17 - Albert Einstein arrived in the United States as a refugee from Nazi Germany. October 19

November


- November 4 - In Paris, a burglar tries to rob an antique store wearing an armor suit but is captured.
- November 8 - Great Depression: New Deal - US President Franklin D. Roosevelt unveils the Civil Works Administration, an organization designed to create jobs for more than 4 million of the unemployed.
- November 11 - Dust Bowl: In South Dakota, a very strong dust storm strips topsoil from desiccated farmlands (this is just one of a series of disastrous dust storms that year).
- November 16 - The United States and the Soviet Union establish formal diplomatic relations.
- November 16 - President of Brazil Getulio Vargas names himself dictator

December


- December 5 - The repeal of prohibition in the United States went into effect.
- December 24 - Train crash in Lagny, France - over 200 dead
- December 26 - The Nissan Motor Company was organized in Tokyo, Japan.
- December 26 - FM radio is patented.
- December 29 - Members of the Iron Guard assassinate Ion Gheorghe Duca, prime minister of Romania

Undated


- British Interplanetary Society founded
- The chocolate chip cookie is invented by Ruth Wakefield.
- The United States Federal Government ends Prohibition and outlaws marijuana.
- Failed coup against Franklin Delano Roosevelt in United States (see Smedley Butler)
- London Passenger Transport Board founded.
- Jimmie Angel becomes the first person to see the Angel Falls, they are named after him.
- Nazi Germany forms the Expert Committee on Questions of Population and Racial Policy under Reich Interior Minister Wilhelm Frick.
- Holodomor took place in Ukraine

Births

January


- January 6 - Oleg Makarov, cosmonaut (d. 2003)
- January 6 - Emil Steinberger, Swiss comedian, director, and writer
- January 8 - Charles Osgood, American journalist and commentator
- January 14 - Stan Brakhage, American filmmaker (d. 2003)
- January 16 - Susan Sontag, American author (d. 2004)
- January 17 - Dalida, French singer (d. 1987)
- January 17 - Sadruddhin Aga Khan, French UN High Commissioner for Refugees (d. 2003)
- January 18 - John Boorman, American film director
- January 23 - Chita Rivera, American actress and dancer
- January 25 - Corazon Aquino, President of the Philippines

February


- February 8 - Elly Ameling, Dutch soprano
- February 12 - Costa-Gavras, Greek-born director and writer
- February 13 - Kim Novak, American actress
- February 14 - Madhubala, Indian actress
- February 18 - Yoko Ono, Japanese-born singer and artist, wife of John Lennon
- February 21 - Nina Simone, American singer (d. 2003)
- February 22- Katharine, Duchess of Kent
- February 27 - Raymond Berry, American football player

March


- March 6 - Ted Abernathy, baseball player (d. 2004)
- March 14 - Michael Caine, English actor
- March 14 - Quincy Jones, American music producer and composer
- March 15 - Ruth Bader Ginsburg, U.S. Supreme Court Justice
- March 15 - Roy Clark, American musician
- March 16 - Sandy Weill, American financier and philanthropist
- March 19 - Philip Roth, American author
- March 22 - May Britt, Swedish actress

April


- April 1 - Claude Cohen-Tannoudji, French physicist, Nobel Prize laureate
- April 5 - Larry Felser, American sports columnist
- April 6 - Roy Goode, British legal academic
- April 12 - Montserrat Caballé, Catalan soprano
- April 12 - Ben Nighthorse Campbell, U.S. Senator
- April 15 - Elizabeth Montgomery, American actress (d. 1995)
- April 16 - Joan Bakewell, British broadcaster
- April 19 - Jayne Mansfield, American actress (d. 1967)
- April 25 - Jerry Leiber, American composer
- April 26 - Carol Burnett, American actress, singer, and comedienne
- April 26 - Arno Allan Penzias, German-born physicist, Nobel Prize laureate
- April 29 - Mark Eyskens, Prime Minister of Belgium

May


- May 3 - James Brown, American musician
- May 3 - Steven Weinberg, American physicist, Nobel Prize laureate
- May 7 - Johnny Unitas, American football player (d. 2002)
- May 10 - Barbara Taylor Bradford, English writer
- May 11 - Louis Farrakhan, American Black Muslim leader
- May 20 - Danny Aiello, American actor
- May 21 - Maurice André, French trumpeter
- May 23 - Joan Collins, English actress
- May 26 - Edward Whittemore, American writer and Central Intelligence agent (d. 1995)
- May 29 - Marc Carbonneau, Canadian terrorist
- May 29 - Helmuth Rilling, German conductor

June


- June 1 - Charles Wilson, American politician
- June 6 - Heinrich Rohrer, Swiss physicist, Nobel Prize laureate
- June 8 - Joan Rivers, American comedienne
- June 11 - Gene Wilder, American actor
- June 13 - Tom King, British politician
- June 17 - Harry Browne, American writer and Presidential candidate
- June 19 - Viktor Patsayev, cosmonaut (d. 1971)
- June 23 - Dave Bristol, baseball manager
- June 26 - Claudio Abbado, Italian conductor
- June 29 - John Bradshaw, American theologian and educator

July


- July 7 - Murray Halberg, New Zealand runner
- July 8 - Marty Feldman, English comedian, actor (d. 1982)
- July 15 - Julian Bream, English guitarist and lutenist
- July 15 - Guido Crepax, Italian comics artist (d. 2003)
- July 21 - John Gardner, American novelist (d. 1982)
- July 23 - Bert Convy, American game show host, actor, and singer (d. 1991)

August


- August 1 - Dom DeLuise, American actor and comedian
- August 10 - Doyle Brunson, American poker player
- August 14 - Richard R. Ernst, Swiss chemist, Nobel Prize laureate
- August 16 - Stuart Roosa, astronaut (d. 1994)
- August 21 - Janet Baker, English mezzo-soprano
- August 23 - Robert Curl, American chemist, Nobel Prize laureate
- August 29 - Arnold Koller, Swiss Federal Councilor

September-October


- September 1 - Ann Richards, Governor of Texas
- September 2 - Mathieu Kérékou, President of Benin
- September 9 - Michael Novak, American philosopher and author
- September 10 - Yevgeny Khrunov, cosmonaut (d. 2000)
- September 17 - Dorothy Loudon, American actress (d. 2003)
- September 15 - Rafael Frübeck de Burgos, Spanish conductor
- September 25 - Hubie Brown, American basketball coach and broadcaster
- October 9 - Peter Mansfield, British physicist, recipient of the Nobel Prize in Physiology or Medicine

November


- November 3 - Michael Dukakis, American politician and Presidential candidate
- November 3 - Amartya Sen, Indian economist, Nobel Prize laureate
- November 19 - Larry King, talk show host
- November 23 - Krzysztof Penderecki, Polish composer

December


- December 2 - Michael Larrabee, American athlete (d. 2003)
- December 3 - Paul J. Crutzen, Dutch chemist, Nobel Prize laureate
- December 6 - Henryk Górecki, Polish composer
- December 9 - Morton Downey, Jr., American television personality (d. 2001)
- December 20 - Jean Carnahan, American politician
- December 23 - Emperor Akihito of Japan
- December 26 - Ugly Dave Grey, Australian television personality

Deaths

January-March


- January 1 - Harriet Brooks, Canadian physicist (b. 1976)
- January 3 - Jack Pickford, Canadian-born actor (b. 1896)
- January 5 - Calvin Coolidge, 30th President of the United States (b. 1872)
- January 7 - Bert Hinkler, Australian pioneer aviator (b. 1892)
- January 31 - John Galsworthy, English writer, Nobel Prize laureate (b. 1867)
- February 12 - Henri Duparc, French composer (b. 1848)
- February 15 - Pat Sullivan, Australian-born director and producer of animated films (b. 1887)
- February 18 - James J. Corbett, American boxer (b. 1866)
- March 6 - Anton Cermak, Mayor of Chicago (assassinated) (b. 1873)
- March 14 - Balto, American sled dog
- March 26 - Eddie Lang, American musician (b. 1902)

April-June


- April 3 - William A. Moffett, U.S. admiral (sinking of the USS Akron) (b. 1869)
- May 24 - Percy C. Mather, missionary
- May 26 - Jimmie Rodgers, American country singer (b. 1897)
- June 2 - Frank Jarvis, American athlete (b. 1878)

July-December


- July 3 - Hipólito Yrigoyen, President of Argentina (b. 1852)
- July 15 - Irving Babbitt, American literary critic (b. 1865)
- July 15 - Freddie Keppard, American jazz musician (b. 1890)
- October 5 - Renée Adorée, French actress (b. 1898)
- November 30 - Arthur Currie, Canadian military leader (b. 1875)
- December 4 - Stefan George, German poet (b. 1868)
- December 8 - Karl Jatho, German airplane pioneer (b. 1873)
- December 25 - Francesc Macià, President of the Generalitat (autonomous government of Catalonia) (b. 1859)

Nobel Prizes


- Physics - Erwin Schrödinger, Paul Adrien Maurice Dirac
- Chemistry - not awarded
- Physiology or Medicine - Thomas Hunt Morgan
- Literature - Ivan Alekseyevich Bunin
- Peace - Sir Norman Angell (Ralph Lane) Category:1933 ko:1933년 ms:1933 ja:1933年 simple:1933 th:พ.ศ. 2476

Radio

Radio is the wireless transmission of signals, by modulation of electromagnetic waves with frequencies below those of light.

Radio waves

Radio waves are a form of electromagnetic radiation, created whenever a charged object (e.g. an electron) accelerates with a frequency that lies in the radio frequency (RF) portion of the electromagnetic spectrum. In radio, this acceleration is caused by an alternating current in an antenna. Radio frequencies occupy the range from a few tens of hertz to a few hundred gigahertz. Other types of electromagnetic radiation, with frequencies above the RF range are infrared, visible light, ultraviolet, X-rays and gamma rays. Since the energy of an individual photon of radio frequency is too low to remove an electron from an atom, radio waves are classified as non-ionizing radiation.
non-ionizing radiation
Radio transmission diagram and electromagnetic waves.
Electromagnetic radiation travels (propagates) by means of oscillating electromagnetic fields that pass through the air and the vacuum of space equally well, and does not require a medium of transport (such as the aether). When radio waves pass an electrical conductor, the oscillating electric or magnetic field (depending on the shape of the conductor) induces an alternating current and voltage in the conductor. This can be transformed into audio or other signals that carry information. Although the word 'radio' is used to describe this phenomenon, the transmissions which we know as television, radio, radar, and cell phone are all classed as radio frequency emissions.

History and invention

The identity of the original inventor of radio, at the time called wireless telegraphy, is contentious. The controversy over who invented the radio, with the benefit of hindsight, can be broken down as follows: :Q1: Who invented 'wireless transmission of data' (spark-gap radio)? :A1: Alexander Popov, Guglielmo Marconi, Nikola Tesla (possibly in that order). :Q2: Who invented amplitude-modulated (AM) radio, so that more than one station can send signals (as opposed to spark-gap radio, where one transmitter covers the entire bandwidth of the spectrum)? :A2: Reginald Fessenden [http://www.invent.org/hall_of_fame/59.html] and Lee de Forest. :Q3: Who invented frequency-modulated (FM) radio, so that an audio signal can avoid "static," that is, interference from electrical equipment and atmospherics? :A3: Edwin H. Armstrong and Lee de Forest. Early radios ran the entire power of the transmitter through a carbon microphone. While some early radios used some type of amplification through electric current or battery, through the mid 1920s the most common type of receiver was the crystal set. In the 1920s, amplifying vacuum tubes revolutionized both radio receivers and transmitters.

Discovery and development

The theoretical basis of the propagation of electromagnetic waves was first described in 1873 by James Clerk Maxwell in his paper to the Royal Society A dynamical theory of the electromagnetic field, which followed his work between 1861 and 1865. In 1878 David E. Hughes was the first to transmit and receive radio waves when he noticed that his induction balance caused noise in the receiver of his homemade telephone. He demonstrated his discovery to the Royal Society in 1880 but was told it was merely induction. It was Heinrich Rudolf Hertz who, between 1886 and 1888, first validated Maxwell's theory through experiment, demonstrating that radio radiation had all the properties of waves (now called Hertzian waves), and discovering that the electromagnetic equations could be reformulated into a partial differential equation called the wave equation. William Henry Ward was issued on April 30, 1872. Mahlon Loomis was issued on July 30, 1872. Landell de Moura, a Brazilian priest and scientist, conducted experiments after 1893 (but at least by 1894). He did not publicize his achievement until 1900. Claims have been made that Nathan Stubblefield invented radio before either Tesla or Marconi, but his device seems to have worked by induction transmission rather than radio transmission.

Wireless age

In 1893 in St. Louis, Missouri, Tesla made devices for his experiments with the electricity. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association, he described and demonstrated in detail the principles of their work. [http://www.ieee-virtual-museum.org/collection/people.php?taid=&id=1234597&lid=1] They contained all the elements that were later incorporated into radio systems before the development of the vacuum tube. He initially experimented with magnetic receivers, unlike the coherers used by Marconi and other early experimenters. [http://www.teslasociety.com/teslarec.pdf]. Tesla is usually considered the first to apply the mechanism of electrical conduction to wireless practices. On 19 August 1894, British physicist Sir Oliver Lodge demonstrated the reception of Morse code signalling using radio waves using a detecting device called a coherer, a tube filled with iron filings which had been invented by Temistocle Calzecchi-Onesti at Fermo in Italy in 1884. Edouard Branly of France and Popov of Russia later produced improved versions of the coherer. Alexander Popov, who was the first to develop a practical communication system based on the coherer, is usually considered to have been the inventor of radio. In 1894 he built a coherer and presented it to the Russian Physical and Chemical Society on May 7 1895 [http://www.ieee.org/organizations/history_center/milestones_photos/popov.html]. In March 1896, he effected transmission of radio waves between different campus buildings in Saint Petersburg, but didn't care to apply for a patent. The Indian physicist, Jagdish Chandra Bose, during the years 1894-1900, performed pioneering research on radio waves and created waves as short as 5 mm. [http://www.ieee-virtual-museum.org/collection/people.php?taid=&id=1234735&lid=1] In November 1894 J.C. Bose ignited gunpowder and rang a bell at a distance using electromagnetic waves, confirming that communication signals can be sent without using wires. But he was not interested in patenting his work too. In 1896 Marconi was awarded what is sometimes recognised as the world's first patent for radio with British Patent 12039, Improvements in transmitting electrical impulses and signals and in apparatus there-for. In 1897 he established the world's first radio station on the Isle of Wight, England. The same year in the U.S., some key developments in radio's early history were created and patented by Tesla. The U.S. Patent Office reversed its decision in 1904, awarding Marconi a patent for the invention of radio, possibly influenced by Marconi's financial backers in the States, who included Thomas Edison and Andrew Carnegie. Some believe this was made for financial reasons, allowing the U.S. government to avoid having to pay the royalties that were being claimed by Tesla for use of his patents. In 1909, Marconi, with Karl Ferdinand Braun, was also awarded the Nobel Prize in Physics for "contributions to the development of wireless telegraphy". However, Tesla's patent (number 645576) was reinstated in 1943 by the U.S. Supreme Court, shortly after his death. This decision was based on the fact that prior art existed before the establishment of Marconi's patent. Some believe the decision was also made for financial reasons, to allow the U.S. government to avoid having to pay damages that were being claimed by the Marconi Company for use of its patents during World War I.

"Wireless" factories and vacuum tubes

Marconi opened the world's first "wireless" factory in Hall Street, Chelmsford, England in 1898, employing around 50 people. Around 1900, Tesla opened the Wardenclyffe Tower facility and advertised services. By 1903, the tower structure neared completion. Various theories exist on how Tesla intended to achieve the goals of this wireless system (reportedly, a 200 kW system). Tesla claimed that Wardenclyffe, as part of a World System of transmitters, would have allowed secure multichannel transceiving of information, universal navigation, time synchronization, and a global location system. The next great invention was the vacuum tube detector, invented by a team of Westinghouse engineers. On Christmas Eve, 1906, Reginald Fessenden (using his heterodyne principle) transmitted the first radio audio broadcast in history from Brant Rock, Massachusetts. Ships at sea heard a broadcast that included Fessenden playing O Holy Night on the violin and reading a passage from the Bible. The world's first radio news program was broadcast August 31, 1920 by station 8MK in Detroit, Michigan. The world's first regular wireless broadcasts for entertainment commenced in 1922 from the Marconi Research Centre at Writtle near Chelmsford, England.

20th century

Developments in the early 20th century (1900-1959):
- Aircraft used commercial AM radio stations for navigation. This continued through the early 1960s when VOR systems finally became widespread (though AM stations are still marked on U.S. aviation charts).
- In the early 1930s, single sideband and frequency modulation were invented by amateur radio operators. By the end of the decade, they were established commercial modes.
- Radio was used to transmit pictures visible as television as early as the 1920s. Standard analog transmissions started in North America and Europe in the 1940s.
- In 1954, Regency introduced a pocket transistor radio, the TR-1, powered by a "standard 22.5V Battery". Developments in the latter half of the 20th century (1960-1999):
- In 1960, Sony introduced their first transistorized radio, small enough to fit in a vest pocket, and able to be powered by a small battery. It was durable, because there were no tubes to burn out. Over the next twenty years, transistors displaced tubes almost completely except for very high power, or very high frequency, uses.
- In 1963 color television was commercially transmitted, and the first (radio) communication satellite, TELSTAR, was launched.
- In the late 1960s, the U.S. long-distance telephone network began to convert to a digital network, employing digital radios for many of its links.
- In the 1970s, LORAN became the premier radio navigation system. Soon, the U.S. Navy experimented with satellite navigation, culminating in the invention and launch of the GPS constellation in 1987.
- In the early 1990s, amateur radio experimenters began to use personal computers with audio cards to process radio signals. In 1994, the U.S. Army and DARPA launched an aggressive, successful project to construct a software radio that could become a different radio on the fly by changing software.
- Digital transmissions began to be applied to broadcasting in the late 1990s.

Uses of radio

software radio software radio Many of radio's early uses were maritime, for sending telegraphic messages using Morse code between ships and land. One of the earliest users included the Japanese Navy scouting the Russian fleet during the Battle of Tsushima in 1905. One of the most memorable uses of marine telegraphy was during the sinking of the RMS Titanic in 1912, including communications between operators on the sinking ship and nearby vessels, and communications to shore stations listing the survivors. Radio was used to pass on orders and communications between armies and navies on both sides in World War I; Germany used radio communications for diplomatic messages once its submarine cables were cut by the British. The United States passed on President Woodrow Wilson's Fourteen Points to Germany via radio during the war. Broadcasting began to become feasible in the 1920s, with the widespread introduction of radio receivers, particularly in Europe and the United States. Besides broadcasting, point-to-point broadcasting, including telephone messages and relays of radio programs, became widespread in the 1920s and 1930s. Another use of radio in the pre-war years was the development of detecting and locating aircraft and ships by the use of radar (RAdio Detecting And Ranging). Today, radio takes many forms, including wireless networks, mobile communications of all types, as well as radio broadcasting. Read more about radio's history. Before the advent of television, commercial radio broadcasts included not only news and music, but dramas, comedies, variety shows, and many other forms of entertainment. Radio was unique among dramatic presentation that it used only sound. For more, see radio programming. There are a number of uses of radio:

Audio


- AM broadcast radio sends music and voice in the Medium Frequency (MF—0.300 MHz to 3 MHz) radio spectrum. AM radio uses amplitude modulation, in which louder sounds at the microphone causes wider fluctuations in the transmitter power while the transmitter frequency remains unchanged. Transmissions are affected by static because lightning and other sources of radio add their radio waves to the ones from the transmitter.
- FM broadcast radio sends music and voice, with higher fidelity than AM radio. In frequency modulation, louder sounds at the microphone cause the transmitter frequency to fluctuate farther, the transmitter power stays constant. FM is transmitted in the Very High Frequency (VHF—30 MHz to 300 MHz) radio spectrum. FM requires more radio frequency space than AM and there are more frequencies available at higher frequencies, so there can be more stations, each sending more information. Another effect is that shorter VHF radio waves act more like light, travelling in straight lines, hence the reception range is generally limited to about 50-100 miles. During unusual upper atmospheric conditions, FM signals are occasionally reflected back towards the Earth by the ionosphere, resulting in Long distance FM reception. FM receivers are subject to the capture effect, which causes the radio to only receive the strongest signal when multiple signals appear on the same frequency. FM receivers are relatively immune to lightning and spark interference.
- FM Subcarrier services are secondary signals transmitted "piggyback" along with the main program. Special receivers are required to utilize these services. Analog channels may contain alternative programming, such as reading services for the blind, background music or stereo sound signals. In some extremely crowded metropolitan areas, the subchannel program might be an alternate foreign language radio program for various ethnic groups. Subcarriers can also transmit digital data, such as station identification, the current song's name, web addresses, or stock quotes. In some countries, FM radios automatically retune themselves to the same channel in a different district by using sub-bands.
- Aviation voice radios use VHF AM. AM is used so that multiple stations on the same channel can be received. (Use of FM would result in stronger stations blocking out reception of weaker stations due to FM's capture effect). Aircraft fly high enough that their transmitters can be received hundreds of miles (kilometres) away, even though they are using VHF.
- Marine voice radios can use AM in the shortwave High Frequency (HF—3 MHz to 30 MHz) radio spectrum for very long ranges or narrowband FM in the VHF spectrum for much shorter ranges.
- Government, police, fire and commercial voice services use narrowband FM on special frequencies. Fidelity is sacrificed to use a smaller range of radio frequencies, usually five kilohertz of deviation (5 thousand cycles per second), rather than the 75 used by FM broadcasts and 25 used by TV sound.
- Civil and military HF (high frequency) voice services use shortwave radio to contact ships at sea, aircraft and isolated settlements. Most use single sideband voice (SSB), which uses less bandwidth than AM. SSB sounds like ducks quacking on an AM radio. Viewed as a graph of frequency versus power, an AM signal shows power where the frequencies of the voice add and subtract with the main radio frequency. SSB cuts the bandwidth in half by suppressing the carrier and (usually) lower sideband. This also makes the transmitter about three times more powerful, because it doesn't need to transmit the unused carrier and sideband.
- TETRA, Terrestrial Trunked Radio is a digital cell phone system for military, police and ambulances.
- Commercial services such as XM and Sirius offer digital Satellite radio.

Telephony


- Cell phones transmit to a local cell transmitter/receiver site, which connects to the public service telephone network through an optic fiber or microwave radio. When the phone leaves the cell radio's area, the central computer switches the phone to a new cell. Cell phones originally used FM, but now most use various digital encodings.
- Satellite phones come in two types: INMARSAT and Iridium. Both types provide world-wide coverage. INMARSAT uses geosynchronous satellites, with aimed high-gain antennas on the vehicles. Iridium provides cell phones, except the cells are satellites in orbit.

Video


- Television sends the picture as AM, and the sound as FM, on the same radio signal.
- Digital television encodes three bits as eight strengths of AM signal. The bits are sent out-of-order to reduce the effect of bursts of radio noise. A Reed-Solomon error correction code lets the receiver detect and correct errors in the data. Although any data could be sent, the standard is to use MPEG-2 for video, and five CD-quality (44.1 kHz) audio channels (center, left, right, left-back and right back). With all this, it takes only half the bandwidth of an analog TV signal because the video data is compressed.

Navigation


- All satellite navigation systems use satellites with precision clocks. The satellite transmits its position, and the time of the transmission. The receiver listens to four satellites, and can figure its position as being on a line that is tangent to a spherical shell around each satellite, determined by the time-of-flight of the radio signals from the satellite. A computer in the receiver does the math.
- Loran systems also used time-of-flight radio signals, but from radio stations on the ground.
- VOR systems (used by aircraft), have a antenna array that transmits two signals simultaneously. A directional signal rotates like a lighthouse at a fixed rate. When the directional signal is facing north, an omnidirectional signal pulses. By measuring the difference in phase of these two signals, an aircraft can determine its bearing from the station. An aircraft can get readings from two VORs, and locate its position at the intersection of the two beams.
- Radio direction-finding is the oldest form of radio navigation. Before 1960 navigators used movable loop antennas to locate commercial AM stations near cities. In some cases they used marine radiolocation beacons, which share a range of frequencies just above AM radio with amateur radio operators.

Radar


- Radar detects things at a distance by bouncing radio waves off them. The delay caused by the echo measures the distance. The direction of the beam determines the direction of the reflection. The polarization and frequency of the return can sense the type of surface.
- Navigational radars scan a wide area two to four times per minute. They use very short waves that reflect from earth and stone. They are common on commercial ships and long-distance commercial aircraft
- General purpose radars generally use navigational radar frequencies, but modulate and polarize the pulse so the receiver can determine the type of surface of the reflector. The best general-purpose radars distinguish the rain of heavy storms, as well as land and vehicles. Some can superimpose sonar data and map data from GPS position.
- Search radars scan a wide area with pulses of short radio waves. They usually scan the area two to four times a minute. Sometimes search radars use the doppler effect to separate moving vehicles from clutter.
- Targeting radars use the same principle as search radar but scan a much smaller area far more often, usually several times a second or more.
- Weather radars resemble search radars, but use radio waves with circular polarization and a wavelength to reflect from water droplets. Some weather radar use the doppler to measure wind speeds.

Emergency services


- emergency position-indicating rescue beacons (EPIRBs), emergency locating transmitters or personal locator beacons are small radio transmitters that satellites can use to locate a person or vehicle needing rescue. Their purpose is to help rescue people in the first day, when survival is most likely. There are several types, with widely-varying performance.

Data (digital radio)


- The oldest form of digital broadcast was spark gap telegraphy, used by pioneers such as Marconi. By pressing the key, the operator could send messages in Morse code by energizing a rotating commutating spark gap. The rotating commutator produced a tone in the receiver, where a simple spark gap would produce a hiss, indistinguishable from static. Spark gap transmitters are now illegal, because their transmissions span several hundred megahertz. This is very wasteful of both radio frequencies and power.
- The next advance was continuous wave telegraphy, or CW, in which a pure radio frequency, produced by a vacuum tube electronic oscillator was switched on and off by a key. A receiver with a local oscillator would "heterodyne" with the pure radio frequency, creating a whistle-like audio tone. CW uses less than 100Hz of bandwidth. CW is still used, these days primarily by amateur radio operators (hams). Strictly, on-off keying of a carrier should be known as "Interrupted Continuous Wave" or ICW.
- Radio teletypes usually operate on short-wave (HF) and are much loved by the military because they create written information without a skilled operator. They send a bit as one of two tones. Groups of five or seven bits become a character printed by a teletype. From about 1925 to 1975, radio teletype was how most commercial messages were sent to less developed countries. These are still used by the military and weather services.
- Aircraft use a 1200 Baud radioteletype service over VHF to send their ID, altitude and position, and get gate and connecting-flight data.
- Microwave dishes on satellites, telephone exchanges and TV stations usually use quadrature amplitude modulation (QAM). QAM sends data by changing both the phase and the amplitude of the radio signal. Engineers like QAM because it packs the most bits into a radio signal. Usually the bits are sent in "frames" that repeat. A special bit pattern is used to locate the beginning of a frame.
- Systems that need reliability, or that share their frequency with other services may use "corrected orthogonal frequency-division multiplexing" or COFDM. COFDM breaks a digital signal into as many as several hundred slower subchannels. The digital signal is often sent as QAM on the subchannels. Modern COFDM systems use a small computer to make and decode the signal with digital signal processing, which is more flexible and far less expensive than older systems that implemented separate electronic channels. COFDM resists fading and ghosting because the narrow-channel QAM signals can be sent slowly. An adaptive system, or one that sends error-correction codes can also resist interference, because most interference can affect only a few of the QAM channels. COFDM is used for WiFi, some cell phones, Digital Radio Mondiale, Eureka 147, and many other local area network, digital TV and radio standards.
- Most new radio systems are digital, see also:Digital TV, Satellite Radio, Digital Audio Broadcasting.

Heating

Radio-frequency energy generated for heating of objects is generally not intended to radiate outside of the generating equipment, to prevent interferance with other radio signals.
- Microwave ovens use intense radio waves to heat food. (Note: It is a common misconception that the radio waves are tuned to the resonant frequency of water molecules. The microwave frequencies used are actually about a factor of 10 below the resonant frequency.)
- Diathermy equipment is used in surgery for sealing of blood vessels.
- Induction furnaces are used for melting metal for casting.

Mechanical Force


- Tractor beams: Radio waves exert small electrostatic and magnetic forces. These are enough to perform station-keeping in microgravity environments.
- Conceptually, Spacecraft propulsion: Radiation pressure from intense radio waves has been proposed as a propulsion method for an interstellar probe called Starwisp. Since the waves are long, the probe could be a very light-weight metal mesh, and thus achieve higher accelerations than if it were a solar sail.

Other

solar sail
- Amateur radio is a hobby where enthusiasts who purchase or build their own equipment and use radio for their own enjoyment. They may also provide an emergency and public-service radio service. This has been of great use, saving lives in many instances. Radio amateurs are able to use frequencies in a large number of narrow bands throughout the radio spectrum. Radio amateurs use all forms of encoding, including obsolete and experimental ones. Several forms of radio were pioneered by radio amateurs and later became commercially important, including FM, single-sideband AM, digital packet radio and satellite repeaters.
- Personal radio services such as Citizens' Band Radio, Family Radio Service, Multi-Use Radio Service and others exist in North America to provide simple, (usually) short range communication for individuals and small groups, without the overhead of licensing. Similar services exist in other parts of the world.
- Wireless energy transfer: A number of schemes have been proposed that transmit power using microwaves, and the technique has been demonstrated. (See Microwave power transmission). These schemes include, for example, solar power stations in orbit beaming energy down to terrestrial users.
- Radio remote control: Use of radio waves to transmit control data to a remote object as in some early forms of guided missile, some early TV remotes and a range of model boats, cars and aeroplanes. Large industrial remote-controlled equipment such as cranes and switching locomotives now usually use digital radio techniques to ensure safety and reliability.

See also


- Satellite radio
- Radio propagation and ionosphere
- Radio programming
- Old-time radio
- Music radio
- International broadcasting
- Amateur radio
- Army No. 11 set
- Shortwave
- Mediumwave
- Longwave
- Near Vertical Incidence Skywave
- Transistor radio
- Crystal radio receiver
- Software radio
- Internet radio
- Types of radio emissions
- Dead air
- Radio astronomy
- Tuner (radio)
- Long distance FM reception (FM DX)
- VFO
- Lists
  - Radio network
  - List of radio stations
  - List of Internet stations

External links


- [http://www.satelliteradionews.net/ Satellite Radio News.Net] Everything you need to know about Satellite Radio.
- Horzepa, Stan, "[http://www.arrl.org/news/features/2003/10/10/1/ Surfin': Who Invented Radio]?". Arrl.org. 10 October 2003.
- IAteacher: [http://www.iateacher.com/Lesson%206/L6P1-Title.htm Interactive Explanation of Radio Receiver Construction]
- U.S. Supreme Court, "[http://caselaw.lp.findlaw.com/scripts/getcase.pl?court=us&vol=320&invol=1 Marconi Wireless Telegraph co. of America v. United States]". 320 U.S. 1. Nos. 369, 373. Argued 9 April-12, 1943. Decided 21 June 1943.
- Radio Locator: [http://www.radio-locator.com/ Find a radio station in your area]
- On The Radio.Net: [http://www.ontheradio.net/ Find phone numbers and websites for commercials you heard on the radio!]
- [http://www.ovrc.org/ Ottawa Vintage Radio Club of Canada]
- [http://www.xmradio.com XM Satellite Radio]
- [http://www.oldradio.com The Broadcast Archive - Radio History on the Web!]
- [http://ndaeuro.online.fr/gargot/index.htm Radiozone]
- Directories
  - [http://www.looksmart.com/eus1/eus317828/eus317855/eus52445/ LookSmart - Radio]
  - [http://dmoz.org/Arts/Radio/ Open Directory Project - Radio]
  - [http://dir.yahoo.com/News_and_Media/Radio/ Yahoo! - Radio] Category:Radio Category:Sound ja:放送 simple:Radio th:วิทยุ

United States

:For alternative meanings, see the disambiguation page for US, USA, United States, or American. The United States of America is a federal democratic republic situated primarily in central North America. It comprises 50 states and one federal district, and has several territories. It is also referred to, with varying formality, as the United States, the U.S., the U.S.A., the States, or simply and most commonly, America. The official founding date of the United States is July 4, 1776, when the Second Continental Congress—representing thirteen British colonies—adopted the Declaration of Independence. However, the structure of the government was profoundly changed in 1788, when the states replaced the Articles of Confederation with the United States Constitution. The date on which each of the fifty states adopted the Constitution is typically regarded as the date that state "entered the Union" (became part of the United States). Since the mid-20th century, following World War II, the United States has emerged as a dominant global influence in economic, political, military, scientific, technological, and cultural affairs.

Geography and climate

The United States shares land borders with Canada (to the north) and Mexico (to the south), and territorial water boundaries with Canada, Russia, the Bahamas, and numerous smaller nations. It is otherwise bounded by the Pacific Ocean and the Bering Sea, in the west; the Arctic Ocean, in the northernmost areas; and the Atlantic Ocean, the Gulf of Mexico, and the Caribbean Sea, in the eastern and southeastern areas. Forty-eight of the states are in the single region between Canada and Mexico; this group is referred to, with varying precision and formality, as the continental or contiguous United States, sometimes abbreviated CONUS, and as the Lower 48. Alaska, which is not included in the term contiguous United States, is at the northwestern end of North America, separated from the Lower 48 by Canada. The archipelago of Hawaii is in the Pacific Ocean. The capital city, Washington, District of Columbia is a federal district located on land donated by the state of Maryland. (Virginia also donated land, but it was returned in 1847.) The United States also has overseas territories with varying levels of independence and organization. When inland water is included in the total area, only Russia and Canada are larger than the United States; if inland water is excluded, China ranks third and the U.S. ranks fourth. The United States' total area is 3,718,711 square miles (9,631,418 km²), of which land makes up 3,537,438 square miles (9,161,923 km²) and water makes up 181,273 square miles (469,495 km²). The United States' landscape is one of the most varied among those of the world's nations: among its many features are temperate forestland and rolling hills, on the east coast; mangrove, in Florida; the Great Plains, in the center of the country; the Mississippi–Missouri river system; the Great Lakes, four of the five of which are shared with Canada; the Rocky Mountains, west of the Great Plains; deserts and temperate coastal zones, west of the Rocky Mountains; and temperate rain forests, in the Pacific northwest. Alaska's tundra, and the volcanic, tropical islands of Hawaii add to the geographic diversity. Hawaii The climate varies along with the landscape, from tropical in Hawaii and southern Florida to tundra in Alaska and atop some of the highest mountains. Most of the North and East experience a temperate continental climate, with warm summers and cold winters. Most of the South experiences a subtropical humid climate with mild winters and long, hot, humid summers. Rainfall decreases markedly from the humid forests of the Eastern Great Plains to the semi-arid shortgrass prairies on the high plains abutting the Rocky Mountains. Arid deserts, including the Mojave, extend through the lowlands and valleys of the southwest, from westernmost Texas to California and northward throughout much of Nevada. Some parts of California have a Mediterranean climate. Rainforests line the windward mountains of the Pacific Northwest from Oregon to Alaska.

History

American history started with the migration of people from Asia across the Bering land bridge approximately 12,000 years ago following large animals that they hunted into the Americas. These Native Americans left evidence of their presence in petroglyphs, burial mounds, and other artifacts. It is estimated that 2-9 million people lived in the territory now occupied by the U.S. before European contact, and the subsequent introduction of foreign diseases such as small pox that greatly diminished the native populations. Some advanced societies were the Anasazi of the southwest, who inhabited Chaco Canyon, and the Woodland Indians, who built Cahokia, located near present-day St Louis, a city with a population of 40,000 at its peak in AD 1200. Vikings first visited North America around 1000, but did not settle permanently. Following the discovery voyages of Christopher Columbus around 1492, other Europeans began to explore and settle there. During the 1500s and 1600s, the Spanish settled parts of the present-day Southwest and Florida, founding St. Augustine, Florida in 1565 and Santa Fe (in what is now New Mexico) in 1607. The first successful English settlement was at Jamestown, Virginia, also in 1607. Within the next two decades, several Dutch settlements, including New Amsterdam (the predecessor to New York City), were established in what are now the states of New York and New Jersey. In 1637, Sweden established a colony at Fort Christina (in what is now Delaware), but lost the settlement to the Dutch in 1655. This was followed by extensive British settlement of the east coast. The British colonists remained relatively undisturbed by their home country until after the French and Indian War, when France ceded Canada and the Great Lakes region to Britain. Britain then imposed taxes on the 13 colonies, widely regarded by the colonists as unfair because they were denied representation in the British Parliament. Tensions between Britain and the colonists increased, and the thirteen colonies eventually rebelled against British rule. British Parliament, George Washington (1789-1797).]] In 1776, the 13 colonies split from Great Britain and formed the United States, the world's first constitutional and democratic federal republic, after their Declaration of Independence of that year, and the Revolutionary War (1775 to 1783). The original political structure was a confederation in 1777, ratified in 1781 as the Articles of Confederation. After long debate, this was supplanted by the Constitution in 1789, forming a more centralized federal government. Prior to all these was the Albany Congress in 1754, in which a union was first seriously proposed. From early colonial times, there was a shortage of labor, which encouraged unfree labor, particularly indentured servitude and slavery. In the mid-19th century, a major division occurred in the United States over the issue of states' rights and the expansion of slavery. The northern states had become opposed to slavery, while the southern states saw it as necessary for the continued success of southern agriculture and wanted it expanded to the territories. Several federal laws were passed in an attempt to settle the dispute, including the Missouri Compromise and the Compromise of 1850. The dispute reached a crisis in 1861, when seven southern states seceded1 from the Union and formed the Confederate States of America, leading to the Civil War. Soon after the war began, four more southern states seceded. During the war, Abraham Lincoln issued the Emancipation Proclamation, mandating the freedom of all slaves in states in rebellion, though full emancipation did not take place until after the end of the war in 1865, the dissolution of the Confederacy, and the Thirteenth Amendment took effect. The Civil War effectively ended the question of a state's right to secede, and is widely accepted as a major turning point after which the federal government became more powerful than state governments. Thirteenth Amendment). The title of the painting, from a 1726 poem by Bishop Berkeley, was a phrase often quoted in the era of Manifest Destiny, expressing a widely held belief that civilization had steadily moved westward throughout history. [http://americanart.si.edu/t2go/1lw/1931.6.1.html (more)] ]] During the 19th century, many new states were added to the original 13 as the nation expanded across the continent. Manifest Destiny was a philosophy that encouraged westward expansion in the United States. As the population of the Eastern states grew and as a steady increase of immigrants entered the country, settlers moved steadily westward across North America. In the process, the U.S. displaced most American Indian nations. This displacement of American Indians continues to be a matter of contention in the U.S. with many tribes attempting to assert their original claims to various lands. In some areas American Indian populations were reduced by foreign diseases contracted through contact with European settlers, and US settlers acquired those emptied lands. In other instances American Indians were removed from their traditional lands by force. Though some would say the U.S. was not a colonial power until the Spanish-American War when it acquired Puerto Rico, Guam and the Philippines, the dominion exercised over land in North America the United States claimed is essentially colonial. The Philippines became independent in 1946. During this period, the nation also became an industrial power. This continued into the 20th century, which has been termed "the American Century" because of the nation's overriding influence on the world. The US became a center for innovation and technological development; major technologies that America either developed or was greatly involved in improving include the telephone, television, computer, the Internet, nuclear weapons, nuclear power, aviation, and aeronautics. In addition to the Civil War, another major traumatic experience for the nation was the Great Depression (1929 to 1939). The nation has also taken part in several major foreign wars, including World War I and World War II (in both of which the US later joined the Allies). During the Cold War, the US was a major player in the Korean War and Vietnam War, and, along with the Soviet Union, was considered one of the world's two "superpowers". With the collapse of the Soviet Union, the US emerged as the world's leading economic and military power. Beginning in the 1990s, the United States became very involved in police actions and peacekeeping, including actions in Kosovo, Haiti, Somalia and Liberia, and the first Persian Gulf War driving Iraq out of Kuwait. After attacks on the World Trade Center and the Pentagon on September 11, 2001, the United States and other allied nations found themselves involved in what has come to be called the "War on Terrorism," which has primarily encompassed military actions in both Afghanistan and Iraq.

Government

Iraq of the United States.]]

Republic and suffrage

The United States is an example of a constitutional republic, with a government composed of and operating through a set of limited powers imposed by its design and enumerated in the United States Constitution. Specifically, the nation operates as a presidential democracy. There are three levels of government: federal, state, and local. Officials of each of these levels are either elected by eligible voters via secret ballot or appointed by other elected officials. Americans enjoy almost universal suffrage from the age of 18 regardless of race, sex, or wealth. There are some limits, however: felons are disenfranchised and in some states former felons are likewise. Furthermore, the national representation of territories and the federal district of Washington, DC in Congress is limited: residents of the District of Columbia are subject to federal laws and federal taxes but their only Congressional representative is a non-voting delegate.

Federal government

The federal government is the national government, comprising the Legislative Branch (led by Congress), the Executive Branch (led by the President), and the Judicial Branch (led by the Supreme Court). These three branches were designed to apply checks and balances on each other. The Constitution limits the powers of the federal government to defense, foreign affairs, the issuing and management of currency, the management of trade and relations between the states, and the protection of human rights. In addition to these explicitly stated powers, the federal government—with the assistance of the Supreme Court—has gradually extended these powers into such areas as welfare and education, on the basis of the "necessary and proper" clause of the Constitution.

The Congress

necessary and proper The Congress of the United States is the legislative branch of the federal government of the United States. It is bicameral, comprising the House of Representatives and the Senate. The House of Representatives consists of 435 members, each of whom represents a congressional district and serves for a two-year term. House seats are apportioned among the states by population; in contrast, each state has two Senators, regardless of population. There are a total of 100 senators, who serve six-year terms. The powers of Congress are limited to those enumerated in the Constitution; all other powers are reserved to the states and the people. The Constitution also includes the necessary-and-proper clause, which grants Congress the power to "make all laws which shall be necessary and proper for carrying into execution the foregoing powers."

The President

necessary-and-proper clause At the top level of the executive branch is the President of the United States. The President and Vice-President are elected as 'running mates' for four-year terms by the Electoral College, for which each state, as well as the District of Columbia, is allocated a number of seats based on its representation (or ostensible representation, in the case of D. C.) in both houses of Congress (see U.S. Electoral College). The relationship between the President and the Congress reflects that between the English monarchy and parliament at the time of the framing of the United States Constitution. Congress can legislate to constrain the President's executive power, even with respect to his or her command of the armed forces; however, this power is used only very rarely—a notable example was the constraint placed on President Richard Nixon's strategy of bombing Cambodia during the Vietnam War. The President cannot directly propose legislation, and must rely on supporters in Congress to promote his or her legislative agenda. The President's signature is required to turn congressional bills into law; in this respect, the President has the power—only occasionally used—to veto congressional legislation. Congress can override a presidential veto with a two-thirds majority vote in both houses. The ultimate power of Congress over the President is that of impeachment or removal of the elected President through a House vote, a Senate trial, and a Senate vote. The threat of using this power has had major political ramifications in the cases of Presidents Andrew Johnson, Richard Nixon, and Bill Clinton. The President makes around 2,000 executive appointments, including members of the Cabinet and ambassadors, which must be approved by the Senate; the President can also issue executive orders and pardons, and has other Constitutional duties, among them the requirement to give a State of the Union address to Congress once a year. Although the President's constitutional role may appear to be constrained, in practice, the office carries enormous prestige that typically eclipses the power of Congress: the Presidency has justifiably been referred to as 'the most powerful office in the world'. The Vice President is first in the line of succession, and is the President of the Senate ex officio, with the ability to cast a tie-breaking vote. The members of the President's Cabinet are responsible for administering the various departments of state, including the Department of Defense, the Justice Department, and the State Department. These departments and department heads have considerable regulatory and political power, and it is they who are responsible for executing federal laws and regulations. George W. Bush is the 43rd President, currently serving his second term.

The Courts

George W. Bush The highest court is the Supreme Court, which consists of nine justices. The court deals with federal and constitutional matters, and can declare legislation made at any level of the government as unconstitutional, nullifying the law and creating precedent for future law and decisions. Below the Supreme Court are the courts of appeals, and below them in turn are the district courts, which are the general trial courts for federal law. Separate from, but not entirely independent of, this federal court system are the individual court systems of each state, each dealing with its own laws and having its own judicial rules and procedures. A case may be appealed from a state court to a federal court only if there is a federal question; the supreme court of each state is the final authority on the interpretation of that state's laws and constitution.

State and local governments

supreme court of each state. Note that Alaska and Hawaii are shown at different scales, and that the Aleutian Islands and the uninhabited Nort