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TV Detector Van
TV detector vans are vans, which, according to the BBC, contain equipment that can detect the presence of television sets in use. The vans are operated by contractors working for the BBC, to enforce the television licensing system in the UK, the Channel Islands and on the Isle of Man. History When television broadcasts in the UK were resumed after a break due to World War 2, it was decided to introduce a television licence fee to finance the service. When first introduced on 1 June 1946, the licence covering the monochrome-only single-channel BBC television service cost £2 (equivalent to £ as of ). The licence was originally issued by the General Post Office (GPO), which was then the regulator of public communications within the UK. Since it was not possible to stop people without a licence from buying and operating a TV, it was necessary to find ways of enforcing the TV licence system. One of the methods used to identify TV use without a licence was TV detection equipment moun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BLW TV Detector Van , Luzon, Philippines
{{Disambiguation ...
BLW or blw may refer to: * Baby-led weaning, an approach to adding complementary foods to a baby's diet of breast milk or formula * Baldwin Locomotive Works, a defunct American manufacturer of railroad locomotives * BLW, the IATA code for Beledweyne Airport, Somalia * BLW, the Indian Railways station code for Balawali railway station, Uttar Pradesh, India * blw, the ISO 639-3 code for Balangao language Balangao or Balangaw (also called Balangao Bontoc) is an Austronesian language spoken in northern Luzon, Philippines. It is spoken in the central area of Mountain Province, and into Tanudan municipality of Kalinga Province ; tl, Lalawigan ng Ka ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oscilloscope
An oscilloscope (informally a scope) is a type of electronic test instrument that graphically displays varying electrical voltages as a two-dimensional plot of one or more signals as a function of time. The main purposes are to display repetitive or single waveforms on the screen that would otherwise occur too briefly to be perceived by the human eye. The displayed waveform can then be analyzed for properties such as amplitude, frequency, rise time, time interval, distortion, and others. Originally, calculation of these values required manually measuring the waveform against the scales built into the screen of the instrument. Modern digital instruments may calculate and display these properties directly. Oscilloscopes are used in the sciences, medicine, engineering, automotive and the telecommunications industry. General-purpose instruments are used for maintenance of electronic equipment and laboratory work. Special-purpose oscilloscopes may be used to analyze an automotive ign ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Band II
Band II is the range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum from 87.5 to 108.0 megahertz (MHz). Radio Band II is primarily used worldwide for FM radio broadcasting. Broadcast television Usage in Russia and in other former members of OIRT In the former Soviet Union and other countries-members of OIRT, frequencies from 76 MHz to 100 MHz were designated for broadcast television usage. Considering 8 MHz channel bandwidth used by the Russian analog television system (System D), the following television channels had been defined: Broadcast television channels 1 and 2 are assigned to VHF I band, channels 6 to 12 are assigned to VHF III Band III is the name of the range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum from 174 to 240 megahertz (MHz). It is primarily used for radio and television broadcasting. It is also called high- ... band. Starting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Band I
Band I is a range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum. The first time there was defined "for simplicity" in Annex 1 of "Final acts of the European Broadcasting Conference in the VHF and UHF bands - Stockholm, 1961". Band I ranges from 47 to 68 MHz for the European Broadcasting Area, and from 54 to 88 MHz for the Americas and it is primarily used for television broadcasting in compliance with ITU Radio Regulations (article 1.38). With the transition to digital TV, most Band I transmitters have already been switched off. Television broadcasting usage Channel spacings vary from country to country, with spacings of 6, 7 and 8 MHz being common. In the UK, Band I was originally used by the BBC for monochrome 405-line television; likewise, the French former 455-line (1937-1939) then 441-line (1943-1956) transmitter on the Eiffel Tower in Paris, and some stations of the French monochrome 819-line system used Band I. Both 405-lin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
405-line Television System
The 405-line monochrome analogue television broadcasting system was the first fully electronic television system to be used in regular broadcasting. The number of television lines influences the image resolution, or quality of the picture. It was introduced with the BBC Television Service in 1936, suspended for the duration of World War II, and remained in operation in the UK until 1985. It was also used between 1961 and 1982 in Ireland, as well as from 1957 to 1973 for the Rediffusion Television cable service in Hong Kong. Sometimes called the Marconi-EMI system, it was developed in 1934 by the EMI Research Team led by Isaac Shoenberg. The figure of 405 lines had been chosen following discussions over Sunday lunch at the home of Alan Blumlein. The system used interlacing; EMI had been experimenting with a 243-line all-electronic interlaced system since 1933. In the 405 system the scanning lines were broadcast in two complementary fields, 50 times per second, creating 25 frame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superheterodyne Receiver
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was long believed to have been invented by US engineer Edwin Armstrong, but after some controversy the earliest patent for the invention is now credited to French radio engineer and radio manufacturer Lucien Lévy. Virtually all modern radio receivers use the superheterodyne principle; except those software-defined radios using ''direct sampling''. History Heterodyne Early Morse code radio broadcasts were produced using an alternator connected to a spark gap. The output signal was at a carrier frequency defined by the physical construction of the gap, modulated by the alternating current signal from the alternator. Since the output frequency of the alternator was generally in the audible range, this produces an audible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Independent Television Authority
The Independent Television Authority (ITA) was an agency created by the Television Act 1954 to supervise the creation of "Independent Television" (ITV (TV network), ITV), the first commercial television network in the United Kingdom. The ITA existed from 1954 until 1972. It was responsible for determining the location, constructing, building, and operating the transmission stations used by the ITV network, as well as determining the exclusive franchise areas and awarding the franchises for each regional commercial broadcasting, broadcaster. The Authority began its operations on 4 August 1954, a mere four days after the Television Act received Royal Assent, under the Chairmanship of Sir Kenneth Clark. The Authority's first Director General, Robert Fraser (ITV), Sir Robert Fraser was appointed by Clark a month later on 14 September. The physics of Very high frequency, VHF broadcasting meant that a comparatively small number of transmitters could cover the majority of the population ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CW Radio
Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimental technologies for transmitting telegraph signals without wires. In radiotelegraphy, information is transmitted by pulses of radio waves of two different lengths called "dots" and "dashes", which spell out text messages, usually in Morse code. In a manual system, the sending operator taps on a switch called a telegraph key which turns the transmitter on and off, producing the pulses of radio waves. At the receiver the pulses are audible in the receiver's speaker as beeps, which are translated back to text by an operator who knows Morse code. Radiotelegraphy was the first means of radio communication. The first practical radio transmitters and receivers invented in 1894–1895 by Guglielmo Marconi used radiotelegraphy. It continued to be the only type of r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beat Frequency Oscillator
In a radio receiver, a beat frequency oscillator or BFO is a dedicated oscillator used to create an audio frequency signal from Morse code radiotelegraphy ( CW) transmissions to make them audible. The signal from the BFO is mixed with the received signal to create a heterodyne or beat frequency which is heard as a tone in the speaker. BFOs are also used to demodulate single-sideband (SSB) signals, making them intelligible, by essentially restoring the carrier that was suppressed at the transmitter. BFOs are sometimes included in communications receivers designed for short wave listeners; they are almost always found in communication receivers for amateur radio, which often receive CW and SSB signals.Larry Wolfgang, Charles Hutchinson (ed), ''The ARRL Handbook for Radio Amateurs Sixty Eighth Edition'', ARRL, -9, pages 12-29,12-30 The beat frequency oscillator was invented in 1901 by Canadian engineer Reginald Fessenden. What he called the "heterodyne" receiver was the first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Wave Radio
In radio, longwave, long wave or long-wave, and commonly abbreviated LW, refers to parts of the radio spectrum with wavelengths longer than what was originally called the medium-wave broadcasting band. The term is historic, dating from the early 20th century, when the radio spectrum was considered to consist of longwave (LW), medium-wave (MW), and short-wave (SW) radio bands. Most modern radio systems and devices use wavelengths which would then have been considered 'ultra-short'. In contemporary usage, the term ''longwave'' is not defined precisely, and its intended meaning varies. It may be used for radio wavelengths longer than 1,000 m i.e. frequencies up to 300 kilohertz (kHz), including the International Telecommunication Union's (ITU's) low frequency (LF, 30–300 kHz) and very low frequency (VLF, 3–30 kHz) bands. Sometimes the upper limit is taken to be higher than 300 kHz, but not above the start of the medium wave broadcast band at 520&nbs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commercial Off-the-shelf
Commercial off-the-shelf or commercially available off-the-shelf (COTS) products are packaged or canned (ready-made) hardware or software, which are adapted aftermarket to the needs of the purchasing organization, rather than the commissioning of custom-made, or bespoke, solutions. A related term, Mil-COTS, refers to COTS products for use by the U.S. military. In the context of the U.S. government, the Federal Acquisition Regulation (FAR) has defined "COTS" as a formal term for commercial items, including services, available in the commercial marketplace that can be bought and used under government contract. For example, Microsoft is a COTS software provider. Goods and construction materials may qualify as COTS but bulk cargo does not. Services associated with the commercial items may also qualify as COTS, including installation services, training services, and cloud services. COTS purchases are alternatives to custom software or one-off developments – government-funded dev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delco Ignition System
The Delco ignition system, also known as the Kettering ignition system, points and condenser ignition or breaker point ignition, is a type of inductive discharge ignition system invented by Charles F. Kettering. It was first sold commercially on the 1912 Cadillac and was manufactured by Delco. Over time, it was used extensively by all automobile and truck manufacturers on spark ignition, i.e., gasoline engines. Today it is still widely used in coil-on-plug, coil-near-plug and in coil packs in distributorless ignitions. An alternative system used in automobiles is capacitor discharge ignition, primarily found now as aftermarket upgrade systems. Electronic ignition was a common term for Kettering inductive ignition with the points (mechanical switch) replaced with an electronic switch such as a transistor. Operation Power Source On initial starting, a storage battery is connected through the ignition switch (called "Contactor" in the figure above). Once the engine is running, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
