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CCIR (selcall)
There are many types and formats of CCIR Selcall. For exampleCCIR 493-4is a standard format for HSelcallfor Land Mobile applications. CCIR (Consultative Committee on International Radio) functions have largely been taken over by ITU-R. One common type of CCIR selcall used in VHF and UHF FM two-way radio communications, is a 5-tone selective calling system mainly found in some European countries and used by the Swedish Police and the Turkish Police. The tone duration of a 5 tone CCIR selcall is 100 millisecond A millisecond (from '' milli-'' and second; symbol: ms) is a unit of time in the International System of Units (SI) equal to one thousandth (0.001 or 10−3 or 1/1000) of a second and to 1000 microseconds. A unit of 10 milliseconds may be ca ...s (± 10 ms) and the tones are transmitted sequentially. References * {{refend Radio technology Telephony signals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency Modulation
Frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. The technology is used in telecommunications, radio broadcasting, signal processing, and Run-length limited#FM: .280.2C1.29 RLL, computing. In Analog signal, analog frequency modulation, such as radio broadcasting, of an audio signal representing voice or music, the instantaneous frequency deviation, i.e. the difference between the frequency of the carrier and its center frequency, has a functional relation to the modulating signal amplitude. Digital data can be encoded and transmitted with a type of frequency modulation known as frequency-shift keying (FSK), in which the instantaneous frequency of the carrier is shifted among a set of frequencies. The frequencies may represent digits, such as '0' and '1'. FSK is widely used in computer modems, such as fax modems, telephone caller ID systems, garage door openers, and other low-frequency transmissions. R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-way Radio
A two-way radio is a radio that can both transmit and receive radio waves (a transceiver), unlike a radio broadcasting, broadcast receiver which only receives content. It is an audio (sound) transceiver, a transmitter and radio receiver, receiver in one unit, used for bidirectional person-to-person voice communication with other users with similar radios. Two-way radios are available in stationary (base station), mobile radio, mobile (installed in vehicles), and hand-held portable models. Hand-held two-way radios are often called walkie-talkies, handie-talkies or hand-helds. Two-way radios are used by groups of geographically separated people who need to keep in continuous voice communication, such as aircraft pilots and air traffic controllers, ship captains and harbormasters, emergency services personnel like firefighters, police officers, and ambulance paramedics, taxi and delivery services, soldiers and military units, fast food and warehouse employees, and radio amateurs. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swedish Police
The Swedish Police Authority ( sv, Polismyndigheten) is the national police force (''Polisen'') of the Kingdom of Sweden. The first modern police force in Sweden was established in the mid-19th century, and the police remained in effect under local government control up until 1965, when it was nationalized and became increasingly centralized, to finally organize under one authority January 1, 2015. Concurrent with this change, the Swedish Security Service formed its own agency. The new authority was created to address shortcomings in the division of duties and responsibilities, and to make it easier for the Government to demand greater accountability. The agency is organized into seven police regions and eight national departments. It is one of the largest government agencies in Sweden, with more than 28,500 employees, of which police officers accounted for approximately 75 percent of the personnel in 2014. It takes two and a half years to become a police officer in Sweden, includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turkish Police
The General Directorate of Security ( tr, Emniyet Genel Müdürlüğü) or Turkish Police Service ( tr, Türk Polis Teşkilatı) is the national civilian police force responsible for law enforcement of the Republic of Turkey, which is affiliated with the Ministry of Interior. Structure In the provinces, it operates under the command of governors ( tr, vali) and district governors ( tr, kaymakam). Civil administrators ( tr, mülki amir) are responsible for the security and well being of towns and districts. The Turkish National Police (TNP) operates within the network of the civil administration system and carries out its duties under the command and control of the civil authority. Town governors and heads of district administrations supervise the force. The TNP is organised as follows: *Central organisation *Provincial organisation **81 Directorates of Provincial Police **751 Police Directorates of Towns affiliated to Provinces **22 Border Gates Police Directorates **18 Free-Zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Millisecond
A millisecond (from '' milli-'' and second; symbol: ms) is a unit of time in the International System of Units (SI) equal to one thousandth (0.001 or 10−3 or 1/1000) of a second and to 1000 microseconds. A unit of 10 milliseconds may be called a centisecond, and one of 100 milliseconds a decisecond, but these names are rarely used. To help compare orders of magnitude of different times, this page lists times between 10−3 seconds and 100 seconds (1 millisecond and one second). ''See also'' times of other orders of magnitude. Examples The Apollo Guidance Computer used metric units internally, with centiseconds used for time calculation and measurement. *1 millisecond (1 ms) – cycle time for frequency 1 kHz; duration of light for typical photo flash strobe; time taken for sound wave to travel about 34 cm; repetition interval of GPS C/A PN code *1 millisecond - time taken for light to travel 204.19 km in a single mode fiber optic cable for a wav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Technology
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by another antenna connected to a radio receiver. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing, and other applications. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking, and satellite communication, among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
