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NXDN
NXDN stands for Next Generation Digital Narrowband, and is an open standard for public land mobile radio systems; that is, systems of two-way radios (transceivers) for bidirectional person-to-person voice communication. It was developed jointly by Icom Incorporated and Kenwood Corporation as an advanced digital system using FSK modulation that supports encrypted transmission and data as well as voice transmission. Like other land mobile systems, NXDN systems use the VHF and UHF frequency bands. It is also used as a niche mode in amateur radio. NXDN is implemented by Icom in their IDAS system and by Kenwood as NEXEDGE; both Kenwood and Icom now offer dual-standard equipment which supports the European dPMR standard. History Icom and Kenwood began their collaboration in 2003. The NXDN protocol was announced in 2005, and NXDN-compatible products first appeared in 2006. The NXDN Common Air Interface (CAI) was accepted at the Study Group 5 (SG5) meeting of the International Tele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kenwood Corporation
is a Japanese brand of consumer electronics. It has been owned by JVCKenwood ever since October 2011, when Kenwood Corporation merged with JVC. Kenwood manufactures audio equipment such as cassette tape decks/recorders, amateur radio (ham) equipment, radios, cellular phones, speakers, and other consumer electronics. History The company was established in 1946 as the Kasuga Radio Co. Ltd. in Komagane City, Nagano Prefecture, Japan. In 1960, the company was renamed Trio Corporation. In 1963, the first overseas office was founded in Los Angeles County, California, USA. In the early 1960s, Trio's products were rebranded by the Lafayette Radio Company, with a focus on citizens' band radio. A&A Trading Co. was an importer of Japanese-made electronics for RadioShack, and a bilingual Japanese-speaking manager from A&A, William "Bill" Kasuga, partnered with George Aratani and Yoichi Nakase to establish a company that would be the exclusive importer of Trio products."Entrepreneur B ... [...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] |
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, with 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 Kenwood C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DPMR
dPMR or digital private mobile radio, is a 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 and Icom; both now offer dual-standard equipment (July 2013). Specifications *Access method: FDMA *Transmission rate: 4,800 bit/s *Modulation: four-level 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 channels. Compliance with EN301 166 at 6.25 kHz for current equipment provides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codec
A codec is a device or computer program that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder. In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or data stream, and hence is a type of codec. ''Endec'' is a portmanteau of encoder/decoder. A coder or encoder encodes a data stream or a signal for transmission or storage, possibly in encrypted form, and the decoder function reverses the encoding for playback or editing. Codecs are used in videoconferencing, streaming media, and video editing applications. History In the mid-20th century, a codec was a device that coded analog signals into digital form using pulse-code modulation (PCM). Later, the name was also applied to software for converting between digital signal formats, including companding functions. Examples An audio codec converts analog audio signals into digital signals for transmission or encodes them for storag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spread Spectrum
In telecommunication and radio communication, spread-spectrum techniques are methods by which a signal (e.g., an electrical, electromagnetic, or acoustic signal) generated with a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth. These techniques are used for a variety of reasons, including the establishment of secure communications, increasing resistance to natural interference, noise, and jamming, to prevent detection, to limit power flux density (e.g., in satellite downlinks), and to enable multiple-access communications. Telecommunications Spread spectrum generally makes use of a sequential noise-like signal structure to spread the normally narrowband information signal over a relatively wideband (radio) band of frequencies. The receiver correlates the received signals to retrieve the original information signal. Originally there were two motivations: either to resist enemy efforts to jam the communication ... [...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] |
Type-accepted
Product certification or product qualification is the process of certifying that a certain product has passed performance tests and quality assurance tests, and meets qualification criteria stipulated in contracts, regulations, or specifications (sometimes called "certification schemes" in the product certification industry). Most product certification bodies (or product certifiers) are accredited to or aligned with ISO/IEC 17065 Conformity assessment -- Requirements for bodies certifying products, processes and services (previously ISO/IEC Guide 65:1996)ISO/IEC Guide 65:1996 an international standard for ensuring competence in those organizations performing product, process and service certifications. The organizations that perform this accreditation are called Accreditation Bodies, and they themselves are assessed by international peers against the ISO 17011 standard. In India Product certification is being monitored by BUREAU OF INDIAN STANDARDS.ISO/IEC 17011:2017 Examples ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encryption
In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decipher a ciphertext back to plaintext and access the original information. Encryption does not itself prevent interference but denies the intelligible content to a would-be interceptor. For technical reasons, an encryption scheme usually uses a pseudo-random encryption key generated by an algorithm. It is possible to decrypt the message without possessing the key but, for a well-designed encryption scheme, considerable computational resources and skills are required. An authorized recipient can easily decrypt the message with the key provided by the originator to recipients but not to unauthorized users. Historically, various forms of encryption have been used to aid in cryptography. Early encryption techniques were often used in milit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SINAD
Signal-to-noise and distortion ratio (SINAD) is a measure of the quality of a signal from a communications device, often defined as : \mathrm = \frac, where P is the average power of the signal, noise and distortion components. SINAD is usually expressed in dB and is quoted alongside the receiver RF sensitivity, to give a quantitative evaluation of the receiver sensitivity. Note that with this definition, unlike SNR, a SINAD reading can never be less than 1 (i.e. it is always positive when quoted in dB). When calculating the distortion, it is common to exclude the DC components. Due to widespread use, SINAD has collected several different definitions. SINAD is commonly defined as: #The ratio of (a) total received power, i.e., the signal to (b) the noise-plus-distortion power. This is modeled by the equation above. #The ratio of (a) the power of a test signal, i.e. a sine wave, to (b) the residual received power, i.e. noise-plus-distortion power. With this definition, it is po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Types Of Radio Emissions
The International Telecommunication Union uses an internationally agreed system for classifying radio frequency signals. Each type of radio emission is classified according to its bandwidth, method of modulation, nature of the modulating signal, and type of information transmitted on the carrier signal. It is based on characteristics of the ''signal'', not on the transmitter used. An emission designation is of the form ''BBBB 123 45'', where ''BBBB'' is the bandwidth of the signal, ''1'' is a letter indicating the type of modulation used of the main carrier (not including any subcarriers which is why FM stereo is F8E and not D8E), ''2'' is a digit representing the type of modulating signal again of the main carrier, ''3'' is a letter corresponding to the type of information transmitted, ''4'' is a letter indicating the practical details of the transmitted information, and ''5'' is a letter that represents the method of multiplexing. The ''4'' and ''5'' fields are optional. This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
