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Digital Private Mobile Radio
dPMR or digital private mobile radio, is a Common Air Interface, common air interface for digital mobile communications. dPMR is an open, non-proprietary standard that was developed by the European Telecommunications Standards Institute (ETSI) and published under the reference ETSI TS 102 658. A simplified version of the dPMR protocol intended for licence-free applications was also published by ETSI under the reference TS 102 490. dPMR is very similar to NXDN protocol implementation by Kenwood Corporation, Kenwood and Icom Incorporated, Icom; both now offer dual-standard equipment (July 2013). Specifications *Access method: FDMA *Transmission rate: 4,800 bit/s *Modulation: four-level frequency-shift keying, FSK What is significant is that dPMR achieves all this in a 6.25 kHz channel. Because the emission mask is so tight, two 6.25 kHz dPMR signals can be used next to each other within a 12.5 kHz channel without causing interference to each other or adjacent chan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RALCWI
A vocoder (, a portmanteau of ''vo''ice and en''coder'') is a category of speech coding that analyzes and synthesizes the human voice signal for audio data compression, multiplexing, voice encryption or voice transformation. The vocoder was invented in 1938 by Homer Dudley at Bell Labs as a means of synthesizing human speech. This work was developed into the channel vocoder which was used as a voice codec for telecommunications for speech coding to conserve bandwidth in transmission. By encrypting the control signals, voice transmission can be secured against interception. Its primary use in this fashion is for secure radio communication. The advantage of this method of encryption is that none of the original signal is sent, only envelopes of the bandpass filters. The receiving unit needs to be set up in the same filter configuration to re-synthesize a version of the original signal spectrum. The vocoder has also been used extensively as an electronic musical instrument. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ETSI
The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization operating 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 and history 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 (EC). 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 officially recognized by the European Union as a European Standards Organisation (ESO), the others being European Committee for Standardization, CEN and CENELEC. The role of the ESOs is to support EU regulation and policies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MPT-1327
MPT 1327 is an industry standard for trunked radio communications networks. First published in January 1988 by the British Radiocommunications Agency, and is primarily used in the United Kingdom, Europe, South Africa, Australia, New Zealand and China. Many countries had their own version of numbering/user interface, including MPT1343 in the UK, Chekker (Regionet 43) in Germany, 3RP (CNET2424) in France, Multiax in Australia, and Gong An in China. MPT systems are still being built in many areas of the world, due to their cost-effectiveness. Digital alternatives The closest direct digital alternative to MPT1327 is NXDN as NXDN virtually replicates MPT1327 using dPMR (digital private mobile radio). Many MPT1327 systems in the UK have been replaced with either Kenwood Communications' NXDN or Motorola Solutions' MOTOTRBO Capacity Plus systems. The TETRA trunked radio standard was developed by the European Telecommunications Standards Institute (ETSI), as a digital alternative ... [...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] |
Electronic Communications Committee
The European Conference of Postal and Telecommunications Administrations (CEPT) was established on 26 June 1959 by nineteen European states in Montreux, Switzerland, as a coordinating body for European state telecommunications and postal organizations. The acronym comes from the French version of its name, . CEPT was responsible for the creation of the European Telecommunications Standards Institute (ETSI) in 1988. Organization CEPT is organised into three main components: * Electronic Communications Committee (ECC) – responsible for radiocommunications and telecommunications matters and formed by the merger of ECTRA (European Committee for Telecommunications Regulatory Affairs) and ERC (European Radiocommunications Committee) in September 2001 **The permanent secretariat of the ECC is the European Communications Office (ECO) * European Committee for Postal Regulation (CERP, after the French ''"Comité européen des régulateurs postaux"'') – responsible for postal matt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PMR446
PMR446 ( Private Mobile Radio, 446 MHz) is a licence-exempt service or UHF CB in the UHF radio frequency band, as personal radio service or citizens band radio, and is available for business and personal use in most countries throughout the European Union, Malaysia, Singapore, Norway, and the United Arab Emirates. PMR446 is typically used for small-site, same-building and line of sight outdoor activities. Equipment use ranges from consumer-grade to professional quality walkie-talkies (similar to those used for FRS/GMRS in the United States and Canada). Depending on surrounding terrain range can vary from a few hundred metres (in a city) to a few kilometres (flat countryside) to many kilometres from high ground. Historically, analogue FM is used but a digital voice mode has been available in radios conforming to digital private mobile radio (dPMR446) and digital mobile radio (DMR Tier 1) standards designed by ETSI. Originally 8 channels were available in analogue mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AMBE+2
An ambe, in anatomy, is a superficial jutting out of a bone. Ambe is also the name of an old surgical instrument, made famous by Hippocrates, for reducing dislocations of the shoulder, so called because its extremity projects like the prominence of a rock. It was described in the Philosophical Transactions of the Royal Society as making a sufficient extension and counter-extension to guide the dislocated bone back into joint.John Martyn Iain David McGeachy (11 September 1948 – 29 January 2009), known professionally as John Martyn, was a British singer-songwriter and guitarist. Over a 40-year career, he released 23 studio albums and received frequent critical acclaim. ..., '' The Philosophical Transactions'' (From the Year 1732, to the Year 1744), Vol. 9, p. 258. References * ;Attribution External linksHippocrates' written description of the tool and its use History of surgery Musculoskeletal system {{treatment-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Air 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 Phase I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency-shift Keying
Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is encoded on a carrier signal by periodically shifting the frequency of the carrier between several discrete frequencies. The technology is used for communication systems such as telemetry, weather balloon radiosondes, caller ID, garage door openers, and low frequency radio transmission in the VLF and ELF bands. The simplest FSK is binary FSK (BFSK, which is also commonly referred to as 2FSK or 2-FSK), in which the carrier is shifted between two discrete frequencies to transmit binary (0s and 1s) information. Modulating and demodulating Reference implementations of FSK modems exist and are documented in detail. The demodulation of a binary FSK signal can be done using the Goertzel algorithm very efficiently, even on low-power microcontrollers. Variations Multiple frequency-shift keying Continuous-phase frequency-shift keying In principle FSK can be implemented by usin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FDMA
Frequency-division multiple access (FDMA) is a channel access method used in some multiple-access protocols. FDMA allows multiple users to send data through a single communication channel, such as a coaxial cable or microwave beam, by dividing the bandwidth of the channel into separate non-overlapping frequency sub-channels and allocating each sub-channel to a separate user. Users can send data through a subchannel by modulating it on a carrier wave at the subchannel's frequency. It is used in satellite communication systems and telephone trunklines. FDMA splits the total bandwidth into multiple channels. Each ground station on the earth is allocated a particular frequency group (or a range of frequencies). Within each group, the ground station can allocate different frequencies to individual channels, which are used by different stations connected to that ground station. Before the transmission begins, the transmitting ground station looks for an empty channel within the freq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
