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WSJT (amateur Radio Software)
WSJT-X is a computer program used for weak-signal radio communication between amateur radio operators. The program was initially written by Joe Taylor, K1JT, but is now open source and is developed by a small team. The digital signal processing techniques in WSJT-X make it substantially easier for amateur radio operators to employ esoteric propagation modes, such as high-speed meteor scatter and moonbounce. Additionally WSJT is able to send signal reports to spotting networks such as PSK Reporter. History WSJT, the predecessor to WSJT-X, was originally released in 2001 and has undergone several major revisions. Communication modes have been both added and removed from the software over the course of its development. Since 2005, the software has been released as open source software under the GNU General Public License. This licensing change required substantial rewrites and took several months to complete. Although Joe Taylor was the original developer (and still acts a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Hooton Taylor Jr
Joseph Hooton Taylor Jr. (born March 29, 1941) is an American astrophysicist and Nobel Prize laureate in Physics for his discovery with Russell Alan Hulse of a "new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation." Early life and education Taylor was born in Philadelphia to Joseph Hooton Taylor Sr. and Sylvia Evans Taylor, both of whom had Quaker roots for many generations, and grew up in Cinnaminson Township, New Jersey. He attended the Moorestown Friends School in Moorestown Township, New Jersey, where he excelled in math. He received a B.A. in physics at Haverford College in 1963, and a Ph.D. in astronomy at Harvard University in 1968. After a brief research position at Harvard, Taylor went to the University of Massachusetts Amherst, eventually becoming Professor of Astronomy and Associate Director of the Five College Radio Astronomy Observatory. Taylor's thesis work was on lunar occultation measurements. About the time ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Würzburg
Würzburg (; Main-Franconian: ) is, after Nuremberg and Fürth, the Franconia#Towns and cities, third-largest city in Franconia located in the north of Bavaria. Würzburg is the administrative seat of the Regierungsbezirk Lower Franconia. It spans the banks of the Main (river), Main river. Würzburg is situated approximately 110 km west-northwest of Nuremberg and 120 km east-southeast of Frankfurt, Frankfurt am Main. The population as of 2019 is approximately 130,000 residents. Würzburg is famous for its partly rebuilt and reconstructed old town and its Würzburger Residenz, a palace that is a List of World Heritage Sites in Germany, UNESCO World Heritage Site. The regional dialect is East Franconian German. History Early and medieval history A Bronze Age Europe, Bronze Age (Urnfield culture) refuge castle, the Celtic Segodunum, and later a Roman Empire, Roman fort, stood on the hill known as the Leistenberg, the site of the present Fortress Marienberg. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-synchronizing Code
In coding theory, especially in telecommunications, a self-synchronizing code is a uniquely decodable code in which the symbol stream formed by a portion of one code word, or by the overlapped portion of any two adjacent code words, is not a valid code word. Put another way, a set of strings (called "code words") over an alphabet is called a self-synchronizing code if for each string obtained by concatenating two code words, the substring starting at the second symbol and ending at the second-last symbol does not contain any code word as substring. Every self-synchronizing code is a prefix code, but not all prefix codes are self-synchronizing. Other terms for self-synchronizing code are synchronized code or, ambiguously, comma-free code. A self-synchronizing code permits the proper framing of transmitted code words provided that no uncorrected errors occur in the symbol stream; external synchronization is not required. Self-synchronizing codes also allow recovery from uncor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Character Code
Character encoding is the process of assigning numbers to graphical character (computing), characters, especially the written characters of human language, allowing them to be stored, transmitted, and transformed using computers. The numerical values that make up a character encoding are known as code points and collectively comprise a code space or a code page. Early character encodings that originated with optical or electrical telegraphy and in early computers could only represent a subset of the characters used in written languages, sometimes restricted to Letter case, upper case letters, Numeral system, numerals and some punctuation only. Over time, character encodings capable of representing more characters were created, such as ASCII, the ISO/IEC 8859 encodings, various computer vendor encodings, and Unicode encodings such as UTF-8 and UTF-16. The Popularity of text encodings, most popular character encoding on the World Wide Web is UTF-8, which is used in 98.2% of surve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baud
In telecommunications and electronics, baud (; symbol: Bd) is a common unit of measurement of symbol rate, which is one of the components that determine the speed of communication over a data channel. It is the unit for symbol rate or modulation rate in symbols per second or pulses per second. It is the number of distinct symbol changes (signalling events) made to the transmission medium per second in a digitally modulated signal or a bd rate line code. Baud is related to '' gross bit rate'', which can be expressed in bits per second (bit/s). If there are precisely two symbols in the system (typically 0 and 1), then baud and bits per second are equivalent. Naming The baud unit is named after Émile Baudot, the inventor of the Baudot code for telegraphy, and is represented according to the rules for SI units. That is, the first letter of its symbol is uppercase (Bd), but when the unit is spelled out, it should be written in lowercase (baud) except when it begins a sentence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiple Frequency-shift Keying
Multiple frequency-shift keying (MFSK) is a variation of frequency-shift keying (FSK) that uses more than two frequencies. MFSK is a form of M-ary orthogonal modulation, where each symbol consists of one element from an alphabet of orthogonal waveforms. M, the size of the alphabet, is usually a power of two so that each symbol represents log2 M bits. * M is usually between 4 and 64 * Error correction is generally also used Fundamentals In a M-ary signaling system like MFSK, an "alphabet" of M tones is established and the transmitter selects one tone at a time from the alphabet for transmission. M is usually a power of 2, so each tone transmission from the alphabet represents log2 M data bits. MFSK is classed as an M-ary orthogonal signaling scheme because each of the M tone detection filters at the receiver responds only to its tone and not at all to the others; this independence provides the orthogonality. Like other M-ary orthogonal schemes, the required Eb/N0 ratio for a giv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contact (amateur Radio)
An amateur radio contact, more commonly referred to as simply a "contact", is an exchange of information between two amateur radio stations. The exchange usually consists of an initial call, a response by another amateur radio operator at an amateur radio station, and a signal report. A contact is often referred to by the Q code QSO. It is often limited to just a minimal exchange of such station IDs. Stations who have made a contact are said to have ''worked'' each other. An operator may also say that he has ''worked'' a certain country. Amateurs use the slang A slang is a vocabulary (words, phrases, and linguistic usages) of an informal register, common in everyday conversation but avoided in formal writing and speech. It also often refers to the language exclusively used by the members of pa ... expression ''ragchew'' or ''ragchewing'' to refer to an extended, informal conversation, a variation of the common idioms "chewing the fat" and "chewing the rag". Sometime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteor
A meteor, known colloquially as a shooting star, is a glowing streak of a small body (usually meteoroid) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere, creating a streak of light via its rapid motion and sometimes also by shedding glowing material in its wake. Although a meteor may seem to be a few thousand feet from the Earth, meteors typically occur in the mesosphere at altitudes from . The root word ''meteor'' comes from the Ancient Greek, Greek ''meteōros'', meaning "high in the air". Millions of meteors occur in Earth's atmosphere daily. Most meteoroids that cause meteors are about the size of a grain of sand, i.e. they are usually millimeter-sized or smaller. Meteoroid sizes can be calculated from their mass and density which, in turn, can be estimated from the observed meteor trajectory in the upper atmosphere. Meteors may occur in meteor shower, showers, which arise when Earth passes throu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteor Scatter
Meteor burst communications (MBC), also referred to as meteor scatter communications, is a radio propagation mode that exploits the ionized trails of meteors during atmospheric entry to establish brief communications paths between radio stations up to apart. There can be forward-scatter or back-scatter of the radio waves. How it works As the Earth moves along its orbital path, millions of particles known as meteoroids enter the Earth's atmosphere every day, a small fraction of which have properties useful for point-to-point communication. When these meteoroids begin to burn up, they create a glowing trail of ionized particles (called a meteor) in the E layer of the atmosphere that can persist for up to several seconds. The ionization trails can be very dense and thus used to reflect radio waves. The frequencies that can be reflected by any particular ion trail are determined by the intensity of the ionization created by the meteor, often a function of the initial size of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth–Moon–Earth Communication
Earth–Moon–Earth communication (EME), also known as Moon bounce, is a radio communications technique that relies on the propagation of radio waves from an Earth-based transmitter directed via reflection from the surface of the Moon back to an Earth-based receiver. History The use of the Moon as a passive communications satellite was proposed by W.J. Bray of the British General Post Office in 1940. It was calculated that with the available microwave transmission powers and low-noise receivers, it would be possible to beam microwave signals up from Earth and reflect them off the Moon. It was thought that at least one voice channel would be possible. Radar reflections off the moon were received and recognized as such in 1943 during German experiments with radio measurement equipment, as reported by Dr. Ing. W. Stepp in ''Der Seewart'' magazine. Stepp noted a "perturbation", which "appeared, had a duration of several impulses, and larger impulse strength than the stronges ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RadCom
''RadCom'' is the monthly magazine published by the Radio Society of Great Britain and is provided to all corporate members of the society. Typically 100 pages, it includes a mixture of news, theory, construction and technical articles of interest to the amateur radio community. ''RadCom'' is the largest circulation amateur radio-related magazine in the United Kingdom. History From its inception in 1913 until the end of 1924, the official journal of the Radio Society of Great Britain was the independent publication ''Wireless World and Radio Review''. Due to a change in proprietorship of that magazine, the honour was withdrawn and bestowed instead on ''Experimental Wireless and the Wireless Engineer''. In July 1925, it was decided by members of the Society's Transmitting and Receiving (T & R) Section to produce its own monthly publication "written by and for the radio amateur". This was entitled ''T & R Bulletin''. The magazine changed its name to ''RSGB Bulletin'' in July 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Spectrum
The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU). Different parts of the radio spectrum are allocated by the ITU for different radio transmission technologies and applications; some 40 radiocommunication services are defined in the ITU's Radio Regulations (RR). In some cases, parts of the radio spectrum are sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for exampl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
