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Inter RF Subsystem Interface
Project 25 (P25 or APCO-25) is a suite of standards for interoperable Land Mobile Radio (LMR) systems designed primarily for public safety users. The standards allow analog conventional, digital conventional, digital trunked, or mixed-mode systems. P25 was originally developed for public safety users in the United States but has gained acceptance for public safety, security, public service, and some commercial applications worldwide. P25 radios are a replacement for analog UHF (typically FM) radios, adding the ability to transfer data as well as voice for more natural implementations of encryption and text messaging. P25 radios are commonly implemented by dispatch organizations, such as police, fire, ambulance and emergency rescue service, using vehicle-mounted radios combined with repeaters and handheld walkie-talkie use. Starting around 2012, products became available with the newer Phase II modulation protocol. The older protocol known as P25 became P25 Phase I. P25 Phas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P25 Hand-held Radios
P, or p, is the sixteenth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''pee'' (pronounced ), plural ''pees''. History The Semitic Pê (mouth), as well as the Greek Π or π ( Pi), and the Etruscan and Latin letters that developed from the former alphabet all symbolized , a voiceless bilabial plosive. Use in writing systems English In English orthography, represents the sound . A common digraph in English is , which represents the sound , and can be used to transliterate ''phi'' in loanwords from Greek. In German, the digraph is common, representing a labial affricate . Most English words beginning with are of foreign origin, primarily French, Latin and Greek; these languages preserve the Proto-Indo-European initial *p. Native English cognates of such words often start with , since English is a Germanic language and thus has undergone Grimm' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambulance
An ambulance is a medically-equipped vehicle used to transport patients to treatment facilities, such as hospitals. Typically, out-of-hospital medical care is provided to the patient during the transport. Ambulances are used to respond to medical emergencies by emergency medical services (EMS), and can rapidly transport paramedics and other first responders, carry equipment for administering emergency care, and transport patients to hospital or other definitive care. Most ambulances use a design based on vans or pickup trucks, though others take the form of motorcycles, buses, hearses, aircraft and boats. Ambulances are generally considered emergency vehicles authorized to be equipped with emergency lights and sirens. Generally, vehicles count as an ambulance if they can transport patients. However, it varies by jurisdiction as to whether a non-emergency patient transport vehicle (also called an ambulette) is counted as an ambulance. These vehicles are not usual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Congress
The United States Congress is the legislature, legislative branch of the federal government of the United States. It is a Bicameralism, bicameral legislature, including a Lower house, lower body, the United States House of Representatives, U.S. House of Representatives, and an Upper house, upper body, the United States Senate, U.S. Senate. They both meet in the United States Capitol in Washington, D.C. Members of Congress are chosen through direct election, though vacancies in the Senate may be filled by a Governor (United States), governor's appointment. Congress has a total of 535 voting members, a figure which includes 100 United States senators, senators and 435 List of current members of the United States House of Representatives, representatives; the House of Representatives has 6 additional Non-voting members of the United States House of Representatives, non-voting members. The vice president of the United States, as President of the Senate, has a vote in the Senate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Communications Commission
The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, internet, wi-fi, satellite, and cable across the United States. The FCC maintains jurisdiction over the areas of broadband access, fair competition, radio frequency use, media responsibility, public safety, and homeland security. The FCC was established pursuant to the Communications Act of 1934 to replace the radio regulation functions of the previous Federal Radio Commission. The FCC took over wire communication regulation from the Interstate Commerce Commission. The FCC's mandated jurisdiction covers the 50 states, the District of Columbia, and the territories of the United States. The FCC also provides varied degrees of cooperation, oversight, and leadership for similar communications bodies in other countries in North America. The FCC is funded entirely by regulatory fees. It has an estimated fiscal-2022 budg ... [...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] |
Public Security
Public security or public safety is the prevention of and protection from events that could endanger the safety and security of the public from significant danger, injury, or property damage. It is often conducted by a state government to ensure the protection of citizens, persons in their territory, organizations, and institutions against threats to their well-being, survival, and prosperity. The public safety issues that a municipality, county, regional, or federal jurisdiction may handle include crimes (ranging from misdemeanors to felonies), structure fires, conflagrations, medical emergencies, mass-casualty incidents, disasters, terrorism, and other concerns. Public safety organizations are organizations that conduct public safety. They generally consist of emergency services and first responders such as law enforcement, fire services, emergency medical services, security forces, and military forces. They are often operated by a government, though some private p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Data
Digital data, in information theory and information systems, is information represented as a string of Discrete mathematics, discrete symbols, each of which can take on one of only a finite number of values from some alphabet (formal languages), alphabet, such as letters or digits. An example is a text document, which consists of a string of alphanumeric characters. The most common form of digital data in modern information systems is ''binary data'', which is represented by a string of binary digits (bits) each of which can have one of two values, either 0 or 1. Digital data can be contrasted with ''analog data'', which is represented by a value from a continuous variable, continuous range of real numbers. Analog data is transmitted by an analog signal, which not only takes on continuous values but can vary continuously with time, a continuous real-valued function of time. An example is the air pressure variation in a sound wave. The word ''digital'' comes from the same sour ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Mobile Radio
Digital Mobile Radio (DMR) is a digital radio Technical standard, standard for voice and data transmission in non-public Radio network, radio networks. It was created by the European Telecommunications Standards Institute (ETSI), and is designed to be low-cost and easy to use. DMR, along with Project 25#Phase 2, P25 phase II and NXDN are the main competitor technologies in achieving 6.25 kHz equivalent bandwidth using the proprietary Multi-Band Excitation, AMBE+2 vocoder. DMR and P25 II both use two-slot Time division multiple access, TDMA in a 12.5 kHz channel, while NXDN uses discrete 6.25 kHz channels using frequency division and TETRA uses a four-slot TDMA in a 25 kHz channel. DMR was designed with three tiers. DMR tiers I (Unlicensed) and II (Conventional Licensed) were first published in 2005, and DMR III (Trunked version) was published in 2012, with manufacturers producing products within a few years of each publication. The primary goal of the standard is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrestrial Trunked Radio
Tetra is the common name of many small freshwater characiform fishes. Tetras come from Africa, Central America, and South America, belonging to the biological families Characidae, Alestidae (the "African tetras"), Lepidarchidae, Lebiasinidae, Acestrorhynchidae, Stevardiidae, and Acestrorhamphidae. In the past, all of these families were placed in the Characidae. The Characidae and their allies are distinguished from other fish by the presence of a small adipose fin between the dorsal and caudal fins. Many of these, such as the neon tetra (''Paracheirodon innesi''), are brightly colored and easy to keep in captivity. Consequently, they are extremely popular for home aquaria. ''Tetra'' is no longer a taxonomic, phylogenetic term. It is short for '' Tetragonopterus'', a genus name formerly applied to many of these fish, which is Greek for "square-finned" (literally, four-sided-wing). Because of the popularity of tetras in the fishkeeping hobby A hobby is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Union
The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The union has a total area of and an estimated population of over 449million as of 2024. The EU is often described as a ''sui generis'' political entity combining characteristics of both a federation and a confederation. Containing 5.5% of the world population in 2023, EU member states generated a nominal gross domestic product (GDP) of around €17.935 trillion in 2024, accounting for approximately one sixth of global economic output. Its cornerstone, the European Union Customs Union, Customs Union, paved the way to establishing European Single Market, an internal single market based on standardised European Union law, legal framework and legislation that applies in all member states in those matters, and only those matters, where the states ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time-division Multiple Access
Time-division multiple access (TDMA) is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same transmission medium (e.g. radio frequency channel) while using only a part of its channel capacity. Dynamic TDMA is a TDMA variant that dynamically reserves a variable number of time slots in each frame to variable bit-rate data streams, based on the traffic demand of each data stream. TDMA is used in digital 2G cellular systems such as Global System for Mobile Communications (GSM), IS-136, Personal Digital Cellular (PDC) and iDEN, in the Maritime Automatic Identification System, and in the Digital Enhanced Cordless Telecommunications (DECT) standard for portable phones. TDMA was first used in satellite communication systems by Wester ... [...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] |
