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Falsing
In telecommunications, falsing is when a decoder assumes that it is detecting a valid input even though one is not present. This is also known as a false decode. This article will discuss analog circuits used before digital signal processing. Examples of decoder falsing include: * a telephone answering machine detecting dial pulses from a rotary dial as ringing voltage, with the result that the answering machine answers in response to dialing. * a two-way radio with an enabled CTCSS decoder turns on the receive audio for one or two syllables of a signal with a close-in-tone-frequency (but wrong) CTCSS tone. The person listening to the radio occasionally hears nonsense partial words from the receiver's speaker: "et"... "up"... * a ringy telephone circuit with SF single-frequency signaling and poor level discipline drops calls because it sees harmonic frequencies or the distorted waveform as a valid "circuit idle" or "on-hook" SF signal. * power line transients cause a telemetry dec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quik Call I
In a conventional, analog two-way radio system, a standard radio has ''noise squelch'' or ''carrier squelch'', which allows a radio to receive all transmissions. Selective calling is used to address a subset of all two-way radios on a single radio frequency channel. Where more than one user is on the same channel (co-channel users), selective calling can address a subset of all receivers or can direct a call to a single radio. Selective calling features fit into two major categories—''individual calling'' and ''group calling''. Individual calls generally have longer time-constants: it takes more air-time to call an individual radio unit than to call a large group of radios. Selective calling is akin to the use of a lock on a door. A radio with carrier squelch is unlocked and will let any signal in. Selective calling locks out all signals except ones with the correct "key", in this case a specific digital code. Selective calling systems can overlap; a radio may have (group call) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CTCSS
In telecommunications, Continuous Tone-Coded Squelch System or CTCSS is one type of in-band signaling that is used to reduce the annoyance of listening to other users on a shared two-way radio communication channel. (See squelch.) It is sometimes referred to as tone squelch. It does this by adding a low frequency audio tone to the voice. Where more than one group of users is on the same radio frequency (called ''co-channel users''), CTCSS circuitry mutes those users who are using a different CTCSS tone or no CTCSS. It is sometimes referred to as a sub-channel, but this is a misnomer because no additional channels are created. All users with different CTCSS tones on the same channel are still transmitting on the identical radio frequency, and their transmissions interfere with each other; however; the interference is masked under most conditions. The CTCSS feature also does not offer any security. A receiver with just a carrier or noise squelch does not suppress any sufficiently s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded drumb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Technology
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by another antenna connected to a radio receiver. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing, and other applications. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking, and satellite communication, among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Electric
General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energy, digital industry, additive manufacturing and venture capital and finance, but has since divested from several areas, now primarily consisting of the first four segments. In 2020, GE ranked among the Fortune 500 as the 33rd largest firm in the United States by gross revenue. In 2011, GE ranked among the Fortune 20 as the 14th most profitable company, but later very severely underperformed the market (by about 75%) as its profitability collapsed. Two employees of GE – Irving Langmuir (1932) and Ivar Giaever (1973) – have been awarded the Nobel Prize. On November 9, 2021, the company announced it would divide itself into three investment-grade public companies. On July 18, 2022, GE unveiled the brand names of the companies it will ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorola
Motorola, Inc. () was an American Multinational corporation, multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011. Motorola Solutions is the legal successor to Motorola, Inc., as the reorganization was structured with Motorola Mobility being spun off. Motorola Mobility was acquired by Lenovo in 2014. Motorola designed and sold wireless network equipment such as cellular transmission base stations and signal amplifiers. Motorola's home and broadcast network products included set-top boxes, digital video recorders, and network equipment used to enable video broadcasting, computer telephony, and high-definition television. Its business and government customers consisted mainly of wireless voice and broadband systems (used to build private networks), and, public safety communicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-out-of-five Code
A two-out-of-five code is a constant-weight code that provides exactly ten possible combinations of two bits, and is thus used for representing the decimal digits using five bits. Each bit is assigned a weight, such that the set bits sum to the desired value, with an exception for zero. According to Federal Standard 1037C: * each decimal digit is represented by a binary numeral consisting of five bits of which two are of one kind, called ''ones'', and three are of the other kind, called ''zeros'', and * the usual weights assigned to the bit positions are 0-1-2-3-6. However, in this scheme, zero is encoded as binary ''01100''; strictly speaking the 0-1-2-3-6 previously claimed is just a mnemonic device. The weights give a unique encoding for most digits, but allow two encodings for 3: 0+3 or 10010 and 1+2 or 01100. The former is used to encode the digit 3, and the latter is used to represent the otherwise unrepresentable zero. The IBM 7070, IBM 7072, and IBM 7074 computers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logical Conjunction
In logic, mathematics and linguistics, And (\wedge) is the truth-functional operator of logical conjunction; the ''and'' of a set of operands is true if and only if ''all'' of its operands are true. The logical connective that represents this operator is typically written as \wedge or . A \land B is true if and only if A is true and B is true, otherwise it is false. An operand of a conjunction is a conjunct. Beyond logic, the term "conjunction" also refers to similar concepts in other fields: * In natural language, the denotation of expressions such as English "and". * In programming languages, the short-circuit and control structure. * In set theory, intersection. * In lattice theory, logical conjunction ( greatest lower bound). * In predicate logic, universal quantification. Notation And is usually denoted by an infix operator: in mathematics and logic, it is denoted by \wedge, or ; in electronics, ; and in programming languages, &, &&, or and. In Jan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DTMF
Dual-tone multi-frequency signaling (DTMF) is a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. DTMF was first developed in the Bell System in the United States, and became known under the trademark Touch-Tone for use in push-button telephones supplied to telephone customers, starting in 1963. DTMF is standardized as ITU-T Recommendation Q.23. It is also known in the UK as ''MF4''. The Touch-Tone system using a telephone keypad gradually replaced the use of rotary dial and has become the industry standard for landline and mobile service. Other multi-frequency systems are used for internal signaling within the telephone network. Multifrequency signaling Before the development of DTMF, telephone numbers were dialed by users with a loop-disconnect (LD) signaling, more commonly known as pulse dialing (dial pulse, DP) in the United States. It functions by int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multi-frequency
In telephony, multi-frequency signaling (MF) is a type of signaling that was introduced by the Bell System after World War II. It uses a combination of audible tones for address (telephone number) transport and supervision signaling on trunk lines between central offices. The signaling is sent ''in-band'' over the same channel as the bearer channel used for voice traffic. Multi-frequency signaling defines electronic signals that consist of a combination of two audible frequencies, usually selected from a set of six frequencies. Over several decades, various types of MF signaling were developed, including national and international varieties. The CCITT standardization process specified the American Bell System version as ''Regional Standard No. 1'', or Signalling System R1, and a corresponding European standard as Signalling System R2. Both were largely replaced by digital systems, such as Signalling System 7, which operate out-of-band on a separate data network. Because of the in-ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ICAO
The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international air transport to ensure safe and orderly growth. ICAO headquarters are located in the '' Quartier International'' of Montreal, Quebec, Canada. The ICAO Council adopts standards and recommended practices concerning air navigation, its infrastructure, flight inspection, prevention of unlawful interference, and facilitation of border-crossing procedures for international civil aviation. ICAO defines the protocols for air accident investigation that are followed by transport safety authorities in countries signatory to the Chicago Convention on International Civil Aviation. The Air Navigation Commission (ANC) is the technical body within ICAO. The commission is composed of 19 commissioners, nominated by the ICAO's contracting states and appo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selcall
Selcall (selective calling) is a type of squelch protocol used in radio communications systems, in which transmissions include a brief burst of sequential audio tones. Receivers that are set to respond to the transmitted tone sequence will open their squelch, while others will remain muted. Selcall is a radio signalling protocol mainly in use in Europe, Asia, Australia and New Zealand, and continues to be incorporated in radio equipment marketed in those areas. Details The transmission of a selcall code involves the generation and sequencing of a series of predefined, audible tones. Both the tone frequencies, and sometimes the tone periods, must be known in advance by both the transmitter and the receiver. Each predefined tone represents a single digit. A series of tones therefore represents a series of digits that represents a number. The number encoded in a selcall burst is used to address one or more receivers. If the receiver is programmed to recognise a certain number, then ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
