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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] |
Digital Radio
Digital radio is the use of digital technology to transmit or receive across the radio spectrum. Digital transmission by radio waves includes digital broadcasting, and especially digital audio radio services. This should not be confused with Internet radio which also is digital but not transmitted by radio waves in the radio spectrum. Types In digital broadcasting systems, the analog audio signal is digitized, compressed using an audio coding format such as AAC+ ( MDCT) or MP2, and transmitted using a digital modulation scheme. The aim is to increase the number of radio programs in a given spectrum, to improve the audio quality, to eliminate fading problems in mobile environments, to allow additional datacasting services, and to decrease the transmission power or the number of transmitters required to cover a region. However, analog radio (AM and FM) is still more popular and listening to radio over IP (Internet Protocol) is growing in popularity. In 2012, four dig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DMR Tier 3 Portable Radio
DMR is an initialism that may refer to: Biology * Differentially methylated regions, a genomic region that is methylated differentially on each parental allele * Dwarf mistletoe rating system, a scale for rating the severity of a dwarf mistletoe infection Government * Device Master Record, a folder containing a technical description of a device controlled by regulating authorities (such as the US Food and Drug Administration) * Discharge Monitoring Report, submission report to the United States Environmental Protection Agency * Department of Main Roads (New South Wales), Australia * Department of Main Roads (Queensland), Australia Media * ''Dance Music Report'', bi-weekly U.S. trade magazine * ''The Des Moines Register'', daily morning newspaper in Des Moines, Iowa * DMR Books, small Chicago-based book publisher Technology * Device Master Record, a compilation of all the instructions, drawings and other records that must be used to produce a product * Differential Microwave ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Repeater
A radio repeater is a combination of a radio receiver and a radio transmitter that receives a signal and retransmits it, so that two-way radio signals can cover longer distances. A repeater sited at a high elevation can allow two mobile stations, otherwise out of line-of-sight propagation range of each other, to communicate. Repeaters are found in professional, commercial, and government mobile radio systems and also in amateur radio. Repeater systems use two different radio frequencies; the mobiles transmit on one frequency, and the repeater station receives those transmission and transmits on a second frequency. Since the repeater must transmit at the same time as the signal is being received, and may even use the same antenna for both transmitting and receiving, frequency-selective filters are required to prevent the receiver from being overloaded by the transmitted signal. Some repeaters use two different frequency bands to provide isolation between input and output or as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amateur Radio
Amateur radio, also known as ham radio, is the use of the radio frequency radio spectrum, spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency, emergency communications. The term ''"radio amateur"'' is used to specify ''"a duly authorized person interested in radioelectric practice with a purely personal aim and without wikt:pecuniary, pecuniary interest"'' (either direct monetary or other similar reward); and to differentiate it from commercial broadcasting, public safety (police and fire), or two-way radio professional services (maritime, aviation, taxis, etc.). The amateur radio service (''amateur service'' and ''amateur-satellite service'') is established by the International Telecommunication Union (ITU) through their recommended radio regulations. National governments regulate technical and operational characteristics of transmissions and issue individual station li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Advanced Multi-Band Excitation
Multi-Band Excitation (MBE) is a series of proprietary speech coding standards developed by Digital Voice Systems, Inc. (DVSI). Overview In 1967 Osamu Fujimura (MIT) showed basic advantages of the multi-band representation of speech ("An Approximation to Voice Aperiodicity", IEEE 1968). This work gave a start to development of the "multi-band excitation" method of speech coding, that was patented in 1997 (now expired) by founders of DVSI as "Multi-Band Excitation" (MBE). All consequent improvements known as ''Improved Multi-Band Excitation'' (IMBE), ''Advanced Multiband Excitation'' (AMBE), AMBE+ and AMBE+2 are based on this MBE method. AMBE is a codebook-based vocoder that operates at bitrates of between 2 and 9.6 kbit/s, and at a sampling rate of 8 kHz in 20-ms frames. The audio data is usually combined with up to 7 bit/s of forward error correction data, producing a total RF bandwidth of approximately 2,250 Hz (compared to 2,700–3,000 Hz for an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Icom Incorporated
is a Japanese manufacturer of radio transmitting and receiving equipment, founded in 1954 by Tokuzo Inoue with the company's original name being "Inoue". Its products now include equipment for radio amateurs, pilots, maritime applications, land mobile professional applications, and radio scanner enthusiasts. Its headquarters are in Osaka, Japan. It has branch offices in the United States (in Kirkland, Washington), Canada (in Delta, British Columbia), Australia (Melbourne, Victoria), New Zealand (Auckland), the United Kingdom (Kent, England), France (Toulouse), Germany ( Bad Soden), Spain (Barcelona) and the People's Republic of China (Beijing). Protocols IDAS IDAS is Icom's implementation of the NXDN protocol for two-way digital radio products intended for commercial Private Land Mobile Radio (PLMR) and low-end public safety communications systems. NXDN is a Common Air Interface (CAI) technical standard for mobile communications. It was developed jointly by Icom and Kenw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kenwood Corporation
is a Japanese brand of consumer electronics. Since October 2008, Kenwood has been owned by JVCKenwood as a result of a merger between Kenwood Corporation and JVC. Kenwood has manufactured electronic equipment such as AM/FM stereo receivers, cassette tape decks/recorders, amateur radio (ham radio) equipment, radios, televisions, cellular phones, speakers, and other consumer electronics. History Kenwood was established in 1946 as the Kasuga Radio Co. Ltd. in Komagane, Nagano Prefecture, Japan. In 1960, the company was renamed Trio Corporation. In 1963, the company established its first overseas office in Los Angeles County, California, United States. During the early 1960s, Trio's products were rebranded and sold by the Lafayette Radio Company, which focused on citizens band (CB) radio. A&A Trading Co. imported Japanese-made electronics for RadioShack. William "Bill" Kasuga, a bilingual Japanese-speaking manager at A&A, partnered with George Aratani and Yoichi Nakase to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yaesu (brand)
Yaesu is a Japanese brand of amateur radio equipment, founded as in 1959 by a Japanese radio amateur Sako Hasegawa (call sign JA1MP) in Yaesu, Japan, a district of Tokyo. History Yaesu had initially been formed with the intention to develop and manufacture commercial and amateur radio transceivers for the Japanese market, but only five years after its formation the company had signed foreign sales agreements for export to Australia and Germany. In Europe, the equipment was sold under the Yaesu brand and the Sommerkamp brand. In 1963 the Swiss firm Sommerkamp imported Yaesu equipment and sold it using their own brand. Yaesu's line of equipment was first imported into the US by Spectronics, Inc. located in Signal Hill, California, in 1965. Yaesu became an important presence in the U.S. amateur radio market with the introduction and improvement of its very popular FT-101 line of equipment in the 1970s. In addition, transceiver manufacture was outsourced to Henry Radio in L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorola
Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois. It was founded by brothers Paul and Joseph Galvin in 1928 and had been named Motorola since 1947. Many of Motorola's products had been radio-related communication equipment such as two-way radios, consumer walkie-talkies, cellular infrastructure, mobile phones, satellite communicators, pagers, as well as cable modems and semiconductors. After having lost $4.3 billion from 2007 to 2009, Motorola was split into two independent public companies: Motorola Solutions (its legal successor) and Motorola Mobility (spun off), on January 4, 2011. Motorola designed and sold wireless network equipment such as cellular transmission base stations and signal amplifiers. Its business and government customers consisted mainly of wireless voice and broadband systems (used to build private networks), and public safety communications systems like Astro and Dimetra. Motorola's h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tait Communications
Tait Communications is a New Zealand radio communications company founded in 1969 by Sir Angus Tait. The company has offices in 17 countries and employs 869 staff (2011). Tait develops voice and data radio technologies, exporting about 95% of products from its Christchurch manufacturing base. Customers include the New Zealand Police, London Buses, Country Fire Authority and Basin Electric Power Cooperative. Competitors include Motorola, Harris Corporation, E.F. Johnson Company, Raytheon, HYT, Selex and EMC spa. History Tait Limited (trading as Tait Communications and formerly known as Tait Electronics Ltd) was founded in 1969 by New Zealand electronics innovator and businessman Sir Angus Tait, KNZM, OBE. The company's founding staff of 12 radio technologists produced the first generation of all-transistor mobile radios in New Zealand. * In 1973, Tait released the Mini-phone series of mobile radios, which were adopted as the industry standard in New Zealand. * In 1979, Ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hytera
Hytera (; previously HYT; ) is a Chinese publicly traded and partly state-owned manufacturer of radio transceivers and radio systems founded in Shenzhen, Guangdong in 1993. Hytera is listed on the Shenzhen Stock Exchange and is partly owned by Shenzhen Investment Holdings of Shenzhen's municipal government. Hytera is major contributor to the PDT Standard, which is designed for public safety organizations in China. The company is a major supplier to China's Ministry of Public Security. History The company's head office is in Shenzhen, China. Hytera's products are developed at three development sites in total. One of the development sites is located in Bad Münder, Germany. In March 2012 Hytera acquired the German company Rohde & Schwarz Professional Mobile Radio GmbH from the German electronics group Rohde & Schwarz, which is now known as Hytera Mobilfunk. In addition, there are Hytera subsidiaries in the US, UK, Canada, and Spain. United States In June 2007, Hytera acquire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
