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Tetra
Terrestrial Trunked Radio (TETRA; formerly known as Trans-European Trunked Radio), a European standard for a trunked radio system, is a professional mobile radio and two-way transceiver specification. TETRA was specifically designed for use by government agencies, emergency services, (police forces, fire departments, ambulance) for public safety networks, rail transport staff for train radios, transport services and the military. TETRA is the European version of trunked radio, similar to Project 25. TETRA is a European Telecommunications Standards Institute (ETSI) standard, first version published 1995; it is mentioned by the European Radiocommunications Committee (ERC). Description TETRA uses time-division multiple access (TDMA) with four user channels on one radio carrier and 25 kHz spacing between carriers. Both point-to-point and point-to-multipoint transfer can be used. Digital data transmission is also included in the standard though at a low data rate. TETRA Mob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Project 25
Project 25 (P25 or APCO-25) is a suite of standards for interoperable digital two-way radio products. P25 was developed by public safety professionals in North America and has gained acceptance for public safety, security, public service, and commercial applications worldwide. P25 radios are a direct replacement for analog UHF (typically FM) radios, but add the ability to transfer data as well as voice, allowing 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 2 modulation protocol, the older protocol known as P25 became P25 phase 1. P25 phase 2 products use the more advanced AMBE2+ vocoder, which allows audio to pass through a more compressed bitstream and provides two TDMA voice ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Professional Mobile Radio
Professional mobile radio (also known as private mobile radio (PMR) in the UK) are person-to-person two-way radio voice communications systems which use portable, mobile, base station, and dispatch console radios. PMR radio systems are based on such standards as MPT-1327, TETRA, APCO 25, and DMR which are designed for dedicated use by specific organizations, or standards such as NXDN intended for general commercial use. These systems are used by police, fire, ambulance, and emergency services, and by commercial firms such as taxis and delivery services. Most systems are half-duplex, in which multiple radios share a common radio channel, and only one can transmit at a time. Transceivers are normally in receive mode, the user presses a push-to-talk button on his microphone when he wants to talk, which turns on his transmitter and turns off his receiver. They use channels in the VHF and UHF bands, giving them a limited range, usually depending on terrain. Output power is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
End-to-end Encryption
End-to-end encryption (E2EE) is a system of communication where only the communicating users can read the messages. In principle, it prevents potential eavesdroppers – including telecom providers, Internet providers, malicious actors, and even the provider of the communication service – from being able to access the cryptographic keys needed to decrypt the conversation. End-to-end encryption is intended to prevent data being read or secretly modified, other than by the true sender and recipient(s). The messages are encrypted by the sender but the third party does not have a means to decrypt them, and stores them encrypted. The recipients retrieve the encrypted data and decrypt it themselves. Because no third parties can decipher the data being communicated or stored, for example, companies that provide end-to-end encryption are unable to hand over texts of their customers' messages to the authorities. In 2022, the UK's Information Commissioner's Office, the government body ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trunked Radio System
A trunked radio system is a two-way radio system that uses a control channel to automatically assign frequency channels to groups of user radios. In a traditional half-duplex land mobile radio system a group of users (a ''talkgroup'') with mobile and portable two-way radios communicate over a single shared radio channel, with one user at a time talking. These systems typically have access to multiple channels, up to 40-60, so multiple groups in the same area can communicate simultaneously. In a conventional (non-trunked) system, channel selection is done manually; before use the group must decide which channel to use, and manually switch all the radios to that channel. This is an inefficient use of scarce radio channel resources because the user group must have exclusive use of their channel regardless of how much or how little they are transmitting. There is also nothing to prevent multiple groups in the same area from choosing the same channel, causing conflicts and 'cross-talk'. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trunked Radio System
A trunked radio system is a two-way radio system that uses a control channel to automatically assign frequency channels to groups of user radios. In a traditional half-duplex land mobile radio system a group of users (a ''talkgroup'') with mobile and portable two-way radios communicate over a single shared radio channel, with one user at a time talking. These systems typically have access to multiple channels, up to 40-60, so multiple groups in the same area can communicate simultaneously. In a conventional (non-trunked) system, channel selection is done manually; before use the group must decide which channel to use, and manually switch all the radios to that channel. This is an inefficient use of scarce radio channel resources because the user group must have exclusive use of their channel regardless of how much or how little they are transmitting. There is also nothing to prevent multiple groups in the same area from choosing the same channel, causing conflicts and 'cross-talk'. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ETSI
The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization in the field of information and communications. ETSI supports the development and testing of global technical standards for ICT-enabled systems, applications and services. Overview ETSI was set up in 1988 by the European Conference of Postal and Telecommunications Administrations ( CEPT) following a proposal from the European Commission. ETSI is the officially recognized body with a responsibility for the standardization of Information and Communication Technologies (ICT). It is one of the three bodies, the others being CEN and CENELEC, officially recognized by the European Union as a European Standards Organization (ESO). The role of the European Standards Organizations is to support EU regulation and policies through the production of Harmonised European Standards and other deliverables. The standards developed by ESOs are the only ones that can be rec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Telecommunications Standards Institute
The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization in the field of Information and communications technology, information and communications. ETSI supports the development and testing of global technical standards for ICT-enabled systems, applications and services. Overview ETSI was set up in 1988 by the European Conference of Postal and Telecommunications Administrations (European Conference of Postal and Telecommunications Administrations, CEPT) following a proposal from the European Commission. ETSI is the officially recognized body with a responsibility for the standardization of Information and Communication Technologies (ICT). It is one of the three bodies, the others being European Committee for Standardization, CEN and CENELEC, officially recognized by the European Union as a European Standards Organization (ESO). The role of the European Standards Organizations is to support EU regulation and poli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambulance
An ambulance is a medically equipped vehicle which transports 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). For this purpose, they are generally equipped with flashing emergency vehicle lighting, warning lights and siren (noisemaker), sirens. They can rapidly transport paramedics and other first responders to the scene, carry equipment for administering emergency medicine, emergency care and transport patients to hospital or other definitive care. Most ambulances use a design based on vans or pickup trucks. Others take the form of Motorcycle ambulance, motorcycles, buses, limousines, Air medical services, aircraft and Water ambulance, boats. Generally, vehicles count as an ambulance if they can transport patients. However, it varies by jurisdiction as to whether a Patient transport, non-emerge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Privately Held Company
A privately held company (or simply a private company) is a company whose shares and related rights or obligations are not offered for public subscription or publicly negotiated in the respective listed markets, but rather the company's stock is offered, owned, traded, exchanged privately, or Over-the-counter (finance), over-the-counter. In the case of a closed corporation, there are a relatively small number of shareholders or company members. Related terms are closely-held corporation, unquoted company, and unlisted company. Though less visible than their public company, publicly traded counterparts, private companies have major importance in the world's economy. In 2008, the 441 list of largest private non-governmental companies by revenue, largest private companies in the United States accounted for ($1.8 trillion) in revenues and employed 6.2 million people, according to ''Forbes''. In 2005, using a substantially smaller pool size (22.7%) for comparison, the 339 companies on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dispatcher
A dispatcher is a communications worker who receives and transmits information to coordinate operations of other personnel and vehicles carrying out a service. A number of organizations, including police and fire departments, emergency medical services, motorcycle couriers, taxicab providers, trucking companies, railroads, and public utility companies, use dispatchers to relay information, direct personnel, and coordinate their operations. Types of dispatchers Emergency dispatchers An emergency dispatcher, also known as public safety dispatcher, 9-1-1 dispatcher, or public safety telecommunicator www.bls.gov ''Occupational Employment and Wages May 2020''. URL accessed on August 19, 2021 receives calls from individuals who require emergency ser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mobile Phone
A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). Modern mobile telephone services use a cellular network architecture and, therefore, mobile telephones are called ''cellular telephones'' or ''cell phones'' in North America. In addition to telephony, digital mobile phones ( 2G) support a variety of other services, such as text messaging, multimedia messagIng, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, video games and digital photography. Mobile phones offering only those capabilities are known as fea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transponder
In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend word, blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a Transponder (aeronautics), flight transponder is an automated transceiver in an aircraft that emits a coded identifying signal in response to an interrogating received signal. In a communications satellite, a Transponder (satellite communications), satellite transponder receives signals over a range of uplink frequencies, usually from a satellite ground station; the transponder amplifies them, and re-transmits them on a different set of downlink frequencies to receivers on Earth, often without changing the content of the received signal or signals. Satellite/broadcast communications A communications satellite’s Communication channel, channels are called transponders because each is a separate transceiver or repeater. With digital video d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
