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Radio Orienteering In A Compact Area
Radio Orienteering in a Compact Area is a variation of Amateur Radio Direction Finding. ROCA is a timed race in which individual competitors use a topographic map and a magnetic compass to navigate through diverse, wooded terrain while searching for radio transmitters. Description ROCA is a sport that requires less athletic skill and more technical radio direction finding skills than ARDF. In a ROCA course, the radio transmitters put out very little power, typically 10 to 200 mW, and can be received over only very short distances. Transmitters may identify themselves in Morse code or with voice recordings, and only transmit for ten seconds during every minute of the competition. The transmitters are physically small, and marked with a control card that is no larger than a typical postcard with a unique number identification. Decoy control cards may be placed in the competition area, as well, to force competitors to locate the actual transmitting devices. Because of the l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postcard
A postcard or post card is a piece of thick paper or thin cardboard, typically rectangular, intended for writing and mailing without an envelope. Non-rectangular shapes may also be used but are rare. There are novelty exceptions, such as wooden postcards, copper postcards sold in the Copper Country of the U.S. state of Michigan, and coconut "postcards" from tropical islands. In some places, one can send a postcard for a lower fee than a letter. Stamp collectors distinguish between postcards (which require a postage stamp) and postal cards (which have the postage pre-printed on them). While a postcard is usually printed and sold by a private company, individual or organization, a postal card is issued by the relevant postal authority (often with pre-printed postage). Production of postcards blossomed in the late 19th and early 20th centuries. As an easy and quick way for individuals to communicate, they became extremely popular. The study and collecting of postcards is terme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orienteering
Orienteering is a group of sports that require navigational skills using a map and compass to navigate from point to point in diverse and usually unfamiliar terrain whilst moving at speed. Participants are given a topographical map, usually a specially prepared orienteering map, which they use to find control points. Originally a training exercise in land navigation for military officers, orienteering has developed many variations. Among these, the oldest and the most popular is foot orienteering. For the purposes of this article, foot orienteering serves as a point of departure for discussion of all other variations, but almost any sport that involves racing against a clock and requires navigation with a map is a type of orienteering. Orienteering is included in the programs of world sporting events including the World Games (see Orienteering at the World Games) and World Police and Fire Games. History The history of orienteering begins in the late 19th century in Swede ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiosport
Radiosport (or radio sport) is formal competition among amateur radio operators in any of three amateur radio activities, ARDF, DXing, and Contesting. The Friendship Radiosport Games is an international multi-sport event that includes all three types of radiosport. Since 1977, the International Amateur Radio Union has sponsored the IARU HF World Championship (originally named the IARU Radiosport Championship). The World Radiosport Team Championship is another international competition. Amateur radio contesting The most common use of the term ''radiosport'' is as a synonym for amateur radio contesting (ham radio contesting). Contesting is an activity where amateur radio stations attempt to make as many two-way contacts with other stations as possible, following certain defined parameters of the competition, to maximize a score. At least two specific contests have used the term ''radiosport'' in their event names; the IARU HF World Championship, a worldwide contest sponsored ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
People's Republic Of China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and borders fourteen countries by land, the most of any country in the world, tied with Russia. Covering an area of approximately , it is the world's third largest country by total land area. The country consists of 22 provinces, five autonomous regions, four municipalities, and two Special Administrative Regions (Hong Kong and Macau). The national capital is Beijing, and the most populous city and financial center is Shanghai. Modern Chinese trace their origins to a cradle of civilization in the fertile basin of the Yellow River in the North China Plain. The semi-legendary Xia dynasty in the 21st century BCE and the well-attested Shang and Zhou dynasties developed a bureaucratic political system to serve hereditary monarchies, or dyna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Francisco Bay
San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland. San Francisco Bay drains water from approximately 40 percent of California. Water from the Sacramento and San Joaquin rivers, and from the Sierra Nevada mountains, flow into Suisun Bay, which then travels through the Carquinez Strait to meet with the Napa River at the entrance to San Pablo Bay, which connects at its south end to San Francisco Bay. It then connects to the Pacific Ocean via the Golden Gate strait. However, this entire group of interconnected bays is often called the ''San Francisco Bay''. The bay was designated a Ramsar Wetland of International Importance on February 2, 2017. Size The bay covers somewhere between , depending on which sub-bays (such as San Pablo Bay), estuaries, wetlands, and so on are included in the measurement. The main part of the bay meas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Navigation
Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation, marine navigation, aeronautic navigation, and space navigation. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks. All navigational techniques involve locating the navigator's position compared to known locations or patterns. Navigation, in a broader sense, can refer to any skill or study that involves the determination of position and direction. In this sense, navigation includes orienteering and pedestrian navigation. History In the European medieval period, navigation was considered part of the set of '' seven mechanical arts'', none of which were used for long voyages across open ocean. Polynesian navigation is probably the earliest form of open-ocean navigation; it was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morse Code
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one of the inventors of the telegraph. International Morse code encodes the 26 basic Latin letters through , one accented Latin letter (), the Arabic numerals, and a small set of punctuation and procedural signals ( prosigns). There is no distinction between upper and lower case letters. Each Morse code symbol is formed by a sequence of ''dits'' and ''dahs''. The ''dit'' duration is the basic unit of time measurement in Morse code transmission. The duration of a ''dah'' is three times the duration of a ''dit''. Each ''dit'' or ''dah'' within an encoded character is followed by a period of signal absence, called a ''space'', equal to the ''dit'' duration. The letters of a word are separated by a space of duration equal to three ''dits'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Racing
In sport, racing is a competition of speed, in which competitors try to complete a given task in the shortest amount of time. Typically this involves traversing some distance, but it can be any other task involving speed to reach a specific goal. A race may be run continuously to finish or may be made up of several segments called heats, stages or legs. A heat is usually run over the same course at different times. A stage is a shorter section of a much longer course or a time trial. Early records of races are evident on pottery from ancient Greece, which depicted running men vying for first place. A chariot race is described in Homer's ''Iliad''. Etymology The word ''race'' comes from a Norse word. This Norse word arrived in France during the invading of Normandy and gave the word ''raz'' which means "swift water" in Brittany, as in a mill race; it can be found in "Pointe du Raz" (the most western point of France, in Brittany), and "''raz-de-marée''" (tsunami). The word rac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watt
The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Watt (1736–1819), an 18th-century Scottish inventor, mechanical engineer, and chemist who improved the Newcomen engine with his own steam engine in 1776. Watt's invention was fundamental for the Industrial Revolution. Overview When an object's velocity is held constant at one metre per second against a constant opposing force of one newton, the rate at which work is done is one watt. : \mathrm In terms of electromagnetism, one watt is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potential difference of one volt (V), meaning the watt is equivalent to the volt-ampere (the latter unit, however, is used for a different quantity from the real power of an electrical circuit). : ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Direction Finding
Direction finding (DF), or radio direction finding (RDF), isin accordance with International Telecommunication Union (ITU)defined as radio location that uses the reception of radio waves to determine the direction in which a radio station or an object is located. This can refer to radio or other forms of wireless communication, including radar signals detection and monitoring (ELINT/ESM). By combining the direction information from two or more suitably spaced receivers (or a single mobile receiver), the source of a transmission may be located via triangulation. Radio direction finding is used in the navigation of ships and aircraft, to locate emergency transmitters for search and rescue, for tracking wildlife, and to locate illegal or interfering transmitters. RDF was important in combating German threats during both the World War II Battle of Britain and the long running Battle of the Atlantic. In the former, the Air Ministry also used RDF to locate its own fighter group ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
