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Electrical Network Frequency Analysis
Electrical network frequency (ENF) analysis is an audio forensics technique for validating audio recordings by comparing frequency changes in background mains hum in the recording with long-term high-precision historical records of mains frequency changes from a database. In effect the mains hum signal is treated as if it were a time-dependent digital watermark that can help identify when the recording was created, detect edits in the recording, or disprove tampering of a recording. Historical records of mains frequency changes are kept on record, e.g., by police in the German federal state of Bavaria since 2010 and the United Kingdom Metropolitan Police since 2005. The technology has been hailed as "the most significant development in audio forensics since Watergate." However, according to a paper by Huijbregtse and Geradts, the ENF technique, although powerful, has significant limitations caused by ambiguity based on fixed frequency offsets during recording, and self-similarity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Forensics
Audio forensics is the field of forensic science relating to the acquisition, analysis, and evaluation of sound recordings that may ultimately be presented as admissible evidence in a court of law or some other official venue. Audio forensic evidence may come from a criminal investigation by law enforcement or as part of an official inquiry into an accident, fraud, accusation of slander, or some other civil incident. The primary aspects of audio forensics are establishing the ''authenticity'' of audio evidence, performing ''enhancement'' of audio recordings to improve speech intelligibility and the audibility of low-level sounds, and ''interpreting and documenting'' sonic evidence, such as identifying talkers, transcribing dialog, and reconstructing crime or accident scenes and timelines. Modern audio forensics makes extensive use of digital signal processing, with the former use of analog filters now being obsolete. Techniques such as adaptive filtering and discrete Fourier tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Recording
Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording. Sound recording is the transcription of invisible vibrations in air onto a storage medium such as a phonograph disc. The process is reversed in sound reproduction, and the variations stored on the medium are transformed back into sound waves. Acoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record (in which a stylus cuts grooves on a record). In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current, which is then converted to a v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mains Hum
Mains hum, electric hum, cycle hum, or power line hum is a sound associated with alternating current which is twice the frequency of the mains electricity. The fundamental frequency of this sound is usually double that of fundamental 50/60 Hz, ''i.e.''100/120Hz, depending on the local power-line frequency. The sound often has heavy harmonic content above 50/60Hz. Because of the presence of mains current in mains-powered audio equipment as well as ubiquitous AC electromagnetic fields from nearby appliances and wiring, 50/60Hz electrical noise can get into audio systems, and is heard as mains hum from their speakers. Mains hum may also be heard coming from powerful electric power grid equipment such as utility transformers, caused by mechanical vibrations induced by magnetostriction in magnetic core. Onboard aircraft (or spacecraft) the frequency heard is often higher pitched, due to the use of 400 Hz AC power in these settings because 400 Hz transformers are much smaller and ligh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mains Frequency
The utility frequency, (power) line frequency (American English) or mains frequency (British English) is the nominal frequency of the oscillations of alternating current (AC) in a wide area synchronous grid transmitted from a power station to the end-user. In large parts of the world this is 50 Hz, although in the Americas and parts of Asia it is typically 60 Hz. Current usage by country or region is given in the list of mains electricity by country. During the development of commercial electric power systems in the late-19th and early-20th centuries, many different frequencies (and voltages) had been used. Large investment in equipment at one frequency made standardization a slow process. However, as of the turn of the 21st century, places that now use the 50 Hz frequency tend to use 220–240 V, and those that now use 60 Hz tend to use 100–127 V. Both frequencies coexist today (Japan uses both) with no great technical reason to prefer one over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Watermark
A digital watermark is a kind of marker covertly embedded in a noise-tolerant signal such as audio, video or image data. It is typically used to identify ownership of the copyright of such signal. "Watermarking" is the process of hiding digital information in a carrier signal; the hidden information should,Ingemar J. Cox: ''Digital watermarking and steganography''. Morgan Kaufmann, Burlington, MA, USA, 2008 but does not need to, contain a relation to the carrier signal. Digital watermarks may be used to verify the authenticity or integrity of the carrier signal or to show the identity of its owners. It is prominently used for tracing copyright infringements and for banknote authentication. Like traditional physical watermarks, digital watermarks are often only perceptible under certain conditions, e.g. after using some algorithm.Frank Y. Shih: ''Digital watermarking and steganography: fundamentals and techniques''. Taylor & Francis, Boca Raton, FL, USA, 2008 If a digital watermark ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Register
''The Register'' is a British technology news website co-founded in 1994 by Mike Magee, John Lettice and Ross Alderson. The online newspaper's masthead sublogo is "''Biting the hand that feeds IT''." Their primary focus is information technology news and opinions. Situation Publishing Ltd is listed as the site's publisher. Drew Cullen is an owner and Linus Birtles is the managing director. Andrew Orlowski was the executive editor before leaving the website in May 2019. History ''The Register'' was founded in London as an email newsletter called ''Chip Connection''. In 1998 ''The Register'' became a daily online news source. Magee left in 2001 to start competing publications ''The Inquirer'', and later the ''IT Examiner'' and ''TechEye''.Walsh, Bob (2007). ''Clear Blogging: How People Blogging Are Changing the World and How You Can Join Them.'' Apress, In 2002, ''The Register'' expanded to have a presence in London and San Francisco, creating ''The Register USA'' at ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bavaria
Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total land area of Germany. With over 13 million inhabitants, it is second in population only to North Rhine-Westphalia, but due to its large size its population density is below the German average. Bavaria's main cities are Munich (its capital and largest city and also the third largest city in Germany), Nuremberg, and Augsburg. The history of Bavaria includes its earliest settlement by Iron Age Celtic tribes, followed by the conquests of the Roman Empire in the 1st century BC, when the territory was incorporated into the provinces of Raetia and Noricum. It became the Duchy of Bavaria (a stem duchy) in the 6th century AD following the collapse of the Western Roman Empire. It was later incorporated into the Holy Roman Empire, became an ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, and many smaller islands within the British Isles. Northern Ireland shares a land border with the Republic of Ireland; otherwise, the United Kingdom is surrounded by the Atlantic Ocean, the North Sea, the English Channel, the Celtic Sea and the Irish Sea. The total area of the United Kingdom is , with an estimated 2020 population of more than 67 million people. The United Kingdom has evolved from a series of annexations, unions and separations of constituent countries over several hundred years. The Treaty of Union between the Kingdom of England (which included Wales, annexed in 1542) and the Kingdom of Scotland in 170 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metropolitan Police
The Metropolitan Police Service (MPS), formerly and still commonly known as the Metropolitan Police (and informally as the Met Police, the Met, Scotland Yard, or the Yard), is the territorial police force responsible for law enforcement and the prevention of crime in Greater London. In addition, the Metropolitan Police is also responsible for some specialised matters throughout the United Kingdom; these responsibilities include co-ordinating and leading national counter-terrorism measures and the personal safety of specific individuals, such as the Monarch and other members of the Royal Family, members of the Government, and other officials (such as the Leader of the Opposition). The main geographical area of responsibilities of the Metropolitan Police District consists of the 32 London boroughs, but does not include the City of London proper — that is, the central financial district also known as the "Square Mile" — which is policed by a separate force, the City of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watergate Scandal
The Watergate scandal was a major political scandal in the United States involving the administration of President Richard Nixon from 1972 to 1974 that led to Nixon's resignation. The scandal stemmed from the Nixon administration's continual attempts to cover up its involvement in the June 17, 1972, break-in of the Democratic National Committee headquarters at the Washington, D.C., Watergate Office Building. After the five perpetrators were arrested, the press and the Justice Department connected the cash found on them at the time to the Committee for the Re-Election of the President. Further investigations, along with revelations during subsequent trials of the burglars, led the House of Representatives to grant the U.S. House Judiciary Committee additional investigative authority—to probe into "certain matters within its jurisdiction", and led the Senate to create the U.S. Senate Watergate Committee, which held hearings. Witnesses testified that Nixon had approved plans t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-similarity
__NOTOC__ In mathematics, a self-similar object is exactly or approximately similar to a part of itself (i.e., the whole has the same shape as one or more of the parts). Many objects in the real world, such as coastlines, are statistically self-similar: parts of them show the same statistical properties at many scales. Self-similarity is a typical property of fractals. Scale invariance is an exact form of self-similarity where at any magnification there is a smaller piece of the object that is similar to the whole. For instance, a side of the Koch snowflake is both symmetrical and scale-invariant; it can be continually magnified 3x without changing shape. The non-trivial similarity evident in fractals is distinguished by their fine structure, or detail on arbitrarily small scales. As a counterexample, whereas any portion of a straight line may resemble the whole, further detail is not revealed. A time developing phenomenon is said to exhibit self-similarity if the numerical v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Power
Electric power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Standard prefixes apply to watts as with other SI units: thousands, millions and billions of watts are called kilowatts, megawatts and gigawatts respectively. A common misconception is that electric power is bought and sold, but actually electrical energy is bought and sold. For example, electricity is sold to consumers in kilowatt-hours (kilowatts multiplied by hours), because energy is power multiplied by time. Electric power is usually produced by electric generators, but can also be supplied by sources such as electric batteries. It is usually supplied to businesses and homes (as domestic mains electricity) by the electric power industry through an electrical grid. Electric power can be delivered over long distances by transmission lines and used for applications such as motion, light or heat with high efficiency. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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