Sunday, April 26, 2009
On the sea voyage home in 1832, Morse encountered Charles Thomas Jackson of Boston who was well schooled in electromagnetism. Witnessing various experiments with Jackson's electromagnet, Morse developed the concept of a single wire telegraph, and The Gallery of the Louvre was set aside. The original Morse telegraph, submitted with his patent application, is part of the collections of the National Museum of American History at the Smithsonian Institution. In time the Morse code would become the primary language of telegraphy in the world, and is still the standard for rhythmic transmission of data.
William Cooke and Professor Charles Wheatstone reached the stage of launching a commercial telegraph prior to Morse, despite starting later. In England, Cooke became fascinated by electrical telegraph in 1836, four years after Morse, but with greater financial resources. Cooke abandoned his primary subject of anatomy and built a small electrical telegraph within three weeks. Wheatstone also was experimenting with telegraphy and (most importantly) understood that a single large battery would not carry a telegraphic signal over long distances, and that numerous small batteries were far more successful and efficient in this task (Wheatstone was building on the primary research of Joseph Henry, an American physicist). Cooke and Wheatstone formed a partnership and patented the electrical telegraph in May 1837, and within a short time had provided the Great Western Railway with a 13-mile (21 km) stretch of telegraph. However, Cooke and Wheatstone's multiple wire signaling method would be overtaken by Morse's superior method within a few years.
Morse encountered the problem of getting a telegraphic signal to carry over more than a few hundred yards of wire. His breakthrough came from the insights of Professor Leonard Gale, who taught chemistry at New York University (a personal friend of Joseph Henry). With Gale's help, Morse soon was able to send a message through ten miles (16 km) of wire. This was the great breakthrough Morse had been seeking. Morse and Gale were soon joined by a young enthusiastic man, Alfred Vail, who had excellent skills, insights and money. Morse's telegraph now began to be developed very rapidly.
In 1838 a trip to Washington, D.C. failed to attract federal sponsorship for a telegraph line. Morse then traveled to Europe seeking both sponsorship and patents, but in London discovered Cooke and Wheatstone had already established priority. Morse would need the financial backing of Maine congressman Francis Ornand Jonathan Smith.
Morse made one last trip to Washington, D.C., in December 1842, stringing "wires between two committee rooms in the Capitol, and sent messages back and forth" to demonstrate his telegraph system.³ Congress appropriated $30,000 in 1843 for construction of an experimental 38-mile (61 km) telegraph line between Washington, D.C., and Baltimore, Maryland, along the right-of-way of the Baltimore and Ohio Railroad. An impressive demonstration occurred on May 1, 1844, when news of the Whig Party's nomination of Henry Clay for U.S. President was telegraphed from the party's convention in Baltimore to the Capitol Building in Washington.. On May 24, 1844, the line was officially opened as Morse sent his famous words "What hath God wrought" from the B&O's Baltimore station to the Capitol Building along the wire.In May 1845 the Magnetic Telegraph Company was formed in order to radiate telegraph lines from New York City towards Philadelphia, Boston, Buffalo, New York and the Mississippi.
Morse also at one time adopted Wheatstone and Carl August von Steinheil's idea of broadcasting an electrical telegraph signal through a body of water or down steel railroad tracks or anything conductive. He went to great lengths to win a lawsuit for the right to be called "inventor of the telegraph", and promoted himself as being an inventor, but Alfred Vail played an important role in the invention of the Morse Code, which was based on earlier codes for the electromagnetic telegraph.
Samuel Morse received a patent for the telegraph in 1847, at the old Beylerbeyi Palace (the present Beylerbeyi Palace was built in 1861-1865 on the same location) in Istanbul, which was issued by Sultan Abdülmecid who personally tested the new invention.
In the 1850s, Morse went to Copenhagen and visited the Thorvaldsens Museum, where the sculptor's grave is in the inner courtyard. He was received by King Frederick VII, who decorated him with the Order of the Dannebrog. Morse expressed his wish to donate his portrait from 1830 to the king. The Thorvaldsen portrait today belongs to Margaret II of Denmark.
The Morse telegraphic apparatus was officially adopted as the standard for European telegraphy in 1851. Britain (with its British Empire) remained the only notable part of the world where other forms of electrical telegraph were in widespread use (they continued to use the needle telegraph invention of Cooke and Wheatstone).
Friday, October 17, 2008
Amateur radio, often called ham radio, is both a hobby and a service in which participants, called "hams," use various types of radio communications equipment to communicate with other radio amateurs for public service, recreation and self-training.
Amateur radio operators enjoy personal (and often worldwide) wireless communications with each other and are able to support their communities with emergency and disaster communications if necessary, while increasing their personal knowledge of electronics and radio theory. An estimated six million people throughout the world are regularly involved with amateur radio.
The term "amateur" is not a reflection on the skills of the participants, which are often quite advanced; rather, "amateur" indicates that amateur radio communications are not allowed to be made for commercial or money-making purposes.
Though its origins can be traced to at least the late 1800s, amateur radio, as practiced today, did not begin until the early 1900s. The first listing of amateur radio stations is contained in the First Annual Official Wireless Blue Book of the Wireless Association of America in 1909. This first radio callbook lists wireless telegraph stations in Canada and the United States, including eighty-nine amateur radio stations. As with radio in general, the birth of amateur radio was strongly associated with various amateur experimenters and hobbyists. Throughout its history, amateur radio enthusiasts have made significant contributions to science, engineering, industry, and social services. Research by amateur radio operators has founded new industries, built economies, empowered nations, and saved lives in times of emergency.
Activities and Practices
Radio amateurs use various modes of transmission to communicate. Voice transmissions are most common, with some such as frequency modulation (FM) offering high quality audio, and others such as single sideband (SSB) offering more reliable communications when signals are marginal and bandwidth is restricted.
Radiotelegraphy using Morse code is an activity dating to the earliest days of radio. Technology has moved past the use of telegraphy in nearly all other communications, and a code test is no longer part of most national licensing exams for amateur radio. Many amateur radio operators continue to make use of the mode, particularly on the shortwave bands and for experimental work such as EME (communications), with its inherent signal-to-noise ratio advantages. Morse, using internationally agreed code groups, also allows communications between amateurs who speak different languages. It is also popular with homebrewers as CW-only transmitters are simpler to construct. A similar "legacy" mode popular with home constructors is amplitude modulation (AM), pursued by many vintage amateur radio enthusiasts and aficionados of vacuum tube technology.
For many years, demonstrating a proficiency in Morse code was a requirement to obtain amateur licenses for the high frequency bands (frequencies below 30 MHz), but following changes in international regulations in 2003, countries are no longer required to demand proficiency. As an example, the United States Federal Communications Commission phased out this requirement for all license classes on February 23, 2007.
Modern personal computers have encouraged the use of digital modes such as radioteletype (RTTY), which previously required cumbersome mechanical equipment. Hams led the development of packet radio, which has employed protocols such as TCP/IP since the 1970s. Specialized digital modes such as PSK31 allow real-time, low-power communications on the shortwave bands. Echolink using Voice over IP technology has enabled amateurs to communicate through local Internet-connected repeaters and radio nodes, while IRLP has allowed the linking of repeaters to provide greater coverage area. Automatic link establishment (ALE) has enabled continuous amateur radio networks to operate on the high frequency bands with global coverage. Other modes, such as FSK441 using software such as WSJT, are used for weak signal modes including meteor scatter and EME (communications) communications.
Fast scan amateur television has gained popularity as hobbyists adapt inexpensive consumer video electronics like camcorders and video cards in home computers. Because of the wide bandwidth and stable signals required, amateur television is typically found in the 70 cm (420 MHz–450 MHz) frequency range, though there is also limited use on 33 cm (902 MHz–928 MHz), 23 cm (1240 MHz–1300 MHz) and higher. These requirements also effectively limit the signal range to between 20 and 60 miles (30 km–100 km), however, the use of linked repeater systems can allow transmissions across hundreds of miles.
These repeaters, or automated relay stations, are used on VHF and higher frequencies to increase signal range. Repeaters are usually located on top of a mountain, hill or tall building, and allow operators to communicate over hundreds of square miles using a low power hand-held transceiver. Repeaters can also be linked together by use of other amateur radio bands, landline or the Internet.
Communication satellites called OSCARs (Orbiting Satellite Carrying Amateur Radio) can be accessed, some using a hand-held transceiver (HT) with a stock "rubber duck" antenna. Hams also use the moon, the aurora borealis, and the ionized trails of meteors as reflectors of radio waves. Hams are also often able to make contact with the International Space Station (ISS),as many astronauts and cosmonauts are licensed as Amateur Radio Operators.
Amateur radio operators use their amateur radio station to make contacts with individual hams as well as participating in round table discussion groups or "rag chew sessions" on the air. Some join in regularly scheduled on-air meetings with other amateur radio operators, called "Nets" (as in "networks") which are moderated by a station referred to as "Net Control". Nets can allow operators to learn procedures for emergencies, be an informal round table or be topical, covering specific interests shared by a group.