Look up radiophone, radiotelephone in Wiktionary, the free dictionary.

A radiotelephone is a communications device that allows two or more people to talk using radio. There is disagreement about the definition of the term. There is a conflict between British English usage, American English usage, and historic use. Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ... The term communications is used in a number of disciplines: Communications, also known as communication studies is the academic discipline which studies communication, generally seen as a mixture between media studies and linguistics. ...

Disambiguation

Radiotelephone versus mobile telephone, cellular

English dictionaries describe the term as a compound word formed from the words radio and telephone, and used to describe a wireless telephone.^[1] There is no Radiotelephone entry in Standard Industrial Classification (SIC) and no radiotelephone index entries appear or in the present-day Yellow Pages index of AT&T telephone directories. The Standard Industrial Classification (abbreviated SIC) is a United States government system for classifying industries by a four-digit code. ...

In the US, mobile telephone was more commonly used to refer to a wireless, full duplex radio technology predating late 1980s cellular systems and used to place telephone calls.^[2] Cellular redirects here. ... This article or section does not cite its references or sources. ...

The connection between analog, older mobile telephone technologies and radiotelephone is described in the article Mobile radio telephone, which splits radiotelephone into two words. The term is used to describe the earliest generation of wireless mobile telephone technologies. Mobile radio telephone systems preceded modern cellular mobile telephony technology. ...

Since the advent of cellular telephones, similar technologies such as GSM and PCS are often referred to collectively by non-technical persons as "cell phones," regardless of the underlying technology. There is no cellular telephone entry in Standard Industry Codes (SIC) but two cellular index entries appear in the present-day Yellow Pages index of AT&T telephone directories. Cellular redirects here. ... Global System for Mobile communications (GSM: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. ... PCS may refer to: In medicine: Post-concussion syndrome, a set of symptoms that a person may experience for weeks, months, or even years after a concussion Postcholecystectomy syndrome, the presence of abdominal symptoms after surgery to remove the gallbladder Precordial catch syndrome, a common cause of chest pain complaints...

Radiotelephone versus radiophone

A case for historic US usage of the similar word Radiophone exists in the 1960s.^[3] This term is used to describe push-to-talk two-way radio systems and equipment. “Push to Talk” redirects here. ... Motorola HT1000 hand-held two-way radio A two-way radio is a radio that can both transmit and receive (a transceiver), unlike a broadcast receiver which only receives content one way. ...

There may be confusion between the similar words radiophone and radiotelephone. A historic case of radiotelephone being used for two-way radio was not found. However, since the 1930s the Federal Communications Commission has issued various commercial "radiotelephone operator" licenses and permits to qualified applicants. These allow them to install, service, and maintain voice-only radio transmitter systems for use on ships and aircraft. (Until deregulation in the 1990s they were also required for commercial domestic radio and television broadcast systems. Because of treaty obligations they are still required for engineers of international shortwave broadcast stations.) The certificate currently issued is the General radiotelephone operator license. The FCCs official seal. ... A solid-state, analog shortwave receiver Shortwave radio operates between the frequencies of 3 MHz (3,000 kHz) and 30 MHz (30,000 kHz) [1] and came to be referred to as such in the early days of radio because the wavelengths associated with this frequency range were shorter than... The General Radiotelephone Operator License, or GROL, is a commercial license, as opposed to an amateur radio certificate. ...

Radiotelephone versus phone

The word phone has a long precedent beginning with early US wireless voice systems. The term means analog voice as opposed to early binary communications known as telegraph or Morse Code. This would include systems fitting into the category of two-way radio or one-way voice broadcasts such as coastal maritime weather. The term is still popular in the Amateur Radio community and in US Federal Communications Commission regulations. 1922 Chart of the Morse Code Letters and Numerals Morse code is a method for transmitting telegraphic information, using standardized sequences of short and long elements to represent the letters, numerals, punctuation and special characters of a message. ... Amateur radio station with modern solid-state transceiver featuring LCD display and DSP capabilities Amateur radio, often called ham radio, is a hobby that uses various types of radio broadcasting equipment to communicate with other radio amateurs for public service, recreation and self-training. ... The FCCs official seal. ...

As push-to talk

A simple handheld radiotelephone is sometimes called a "walkie-talkie". CB radio is also a very similar technology. While in recent years the cell phone has largely superseded radiotelephones for the average user, they are still widely used in many more specialist applications, for example police communications, emergency services, taxi services, and private mobile radio networks (PMR). A walkie-talkie is a portable, bi-directional radio transceiver, first developed for military use. ... A typical CB base station. ... Taxicab, short forms taxi or cab, is a type of public transport for a single passenger, or small group of passengers, typically for a non-shared ride. ...

Modes of operation

A standard land line based telephone allows both users to talk and listen simultaneously; effectively there are two open channels between the two end-to-end users of the system. In a radiotelephone system, this form of working, known as full-duplex, is unusual. That's because it would require a radio system to simultaneously transmit and receive on two separate channels, which is both a waste of bandwidth, and presents some technical challenges. It is however, the most comfortable method of voice communication for users, and is used in cell phones. A landline or main line is a telephone line which travels through a physical, land-based medium. ... For other uses, see Telephone (disambiguation). ... Channel, in communications (sometimes called communications channel), refers to the medium used to convey information from a sender (or transmitter) to a receiver. ... This article or section does not cite its references or sources. ... This article does not cite any references or sources. ...

The most common method of working for radiotelephones is single or dual-frequency simplex operation, which allows one person to talk and the other to listen alternately. If a single channel is used, both ends take turns to transmit on it. An eavesdropper would hear both sides of the conversation. Dual frequency working splits the communication into two separate channels, but only one is used to transmit at a time. The end users have the same experience as single frequency simplex, but an eavesdropper would only hear one side of the conversation. A simplex communication system is one where all signals flow in one direction. ...

A halfway house system called half-duplex allows one end to transmit and receive simultaneously, but the other to talk and listen alternately. This article or section does not cite its references or sources. ...

The user presses a special switch on the transmitter when they wish to talk - this is called the "press-to-talk" switch or PTT (colloquially, sometimes called "the tit"). It is usually fitted on the side of the microphone or other obvious position. Users may use a special code-word such as "over" to signal that they have finished transmitting, or it may follow from the conversation. Electrical switches. ... Antenna tower of Crystal Palace transmitter, London A transmitter (sometimes abbreviated XMTR) is an electronic device which with the aid of an antenna propagates an electromagnetic signal such as radio, television, or other telecommunications. ... “Microphones” redirects here. ...

Technology

Radiotelephones may operate at any frequency where they are licensed to do so, though typically they are used in the various bands between 60 and 900 MHz. They may use simple modulation schemes such as AM or FM, or more complex techniques such as digital coding, spread spectrum, and so on. Licensing terms for a given band will usually specify the type of modulation to be used. For example, airband radiotelephones used for air to ground communication between pilots and controllers operates in the VHF band from 118.0 to 136.975 MHz, using amplitude modulation. FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. ... MegaHertz (MHz) is the name given to one million (106) Hertz, a measure of frequency. ... In telecommunications, modulation is the process of varying a periodic waveform, i. ... Amplitude modulation (AM) is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. ... In telecommunications, frequency modulation (FM) conveys information over a carrier wave by varying its frequency. ... Spread-spectrum telecommunications is a technique in which a signal is transmitted in a bandwidth considerably greater than the frequency content of the original information. ... A Bendix/King KY197 Airband VHF communication radio mounted above a Cessna ARC RT-359A Transponder (the beige box) in a light airplane instrument panel. ... Very high frequency (VHF) is the radio frequency range from 30 MHz to 300 MHz. ...

Radiotelephone receiver are usually designed to a very high standard, and are usually of the double-conversion superhet design. Likewise, transmitters are carefully designed to avoid unwanted interference, and feature power outputs from a few tens of milliwatts to perhaps 50 watts for a mobile unit, up to a couple of hundred watts for a base station. Multiple channels are often provided using a frequency synthesiser. In radio terminology, a receiver is an electronic circuit that receives a radio signal from an antenna and decodes the signal for use as sound, pictures, navigational-position information, etc. ... In electronics, the superheterodyne receiver (also known by its full name, the supersonic heterodyne receiver, or by the abbreviated form superhet) is a technique for selectively recovering the information from radio waves of a particular frequency. ... For other uses, see Watt (disambiguation). ... The term base station can be used in the context of land surveying, wireless computer networking, and wireless communications. ... A frequency synthesizer is an electronic system for generating any of a range of frequencies from a single fixed timebase or oscillator. ...

Receivers usually features a squelch circuit to cut off the audio output from the receiver when there is no transmission to listen to. This is in contrast to broadcast receivers which often dispense with this. In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver in the absence of a sufficiently strong desired input signal. ... An electronic circuit is an electrical circuit that also contains active electronic devices such as transistors or vacuum tubes. ... Broadcasting is the distribution of audio and/or video signals which transmit programs to an audience. ... In communications, transmission is the act of transmitting electrical messages (and the associated phenonomena of radiant energy that pass through media). ... Broadcasting is the distribution of audio and/or video signals which transmit programs to an audience. ...

Privacy and selective calling

Main article: Selective calling

Often, on a small network system, there are many mobile units and one main base station. This would be typical for police or taxi services for example. To assist with directing messages to the correct recipients and avoiding irrelevant traffic on the network being a distraction to other units, a variety of means have been devised to create addressing systems. 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 on a channel. ...

The crudest and oldest of these is called CTCSS, or Continuous Tone-Controlled Squelch System. This consists of superimposing a precise very low frequency tone on the audio signal. Only the receiver tuned to this specific tone is able to receive the signal, his receiver shuts off the audio when the tone is not present or is a different frequency. By assigning a unique frequency to each mobile, private channels can be imposed on a public network. However this is only a convenience feature - it does not guarantee privacy. In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver. ...

A more commonly used system is called Selective Calling or Selcall. This also uses audio tones but these are not restricted to subaudio tones, and are sent as a short burst in sequence. The receiver will be programmed to respond only to a unique set of tones in a precise sequence, and only then will it open the audio circuits for open channel conversation with the base station. This system is much more versatile than CTCSS, as relatively few tones yield a far greater number of "addresses". In addition, special features such as broadcast modes and emergency overrides can be designed in, using special addresses set aside for the purpose. A mobile unit can also broadcast a Selcall sequence with her unique address to the base, so they know before the call is picked up which unit is calling. In practice many selcall systems also have automatic transponding built in, which allows the base station to "interrogate" a mobile even if the operator is not present. Such transponding systems usually have a status code that the user can set to indicate what they are doing. Features like this, while very simple, are one reason why they are very popular with organisations that need to manage a large number of remote mobile units. Selcall is widely used, though is becoming superseded by much more sophisticated digital systems. Selcall (selective calling) is a type of squelch protocol used in radio communications systems, in which transmissions are preceded by a brief burst of sequential audio tones. ... An Ontario Highway 407 toll transponder In telecommunication, the term transponder (short-for Transmitter-responder and sometimes abbreviated to XPDR, XPNDR or TPDR) has the following meanings: An automatic device that receives, amplifies, and retransmits a signal on a different frequency (see also broadcast translator). ...

Notes

1. ^ A survey of English dictionaries showed some common views. Some of these follow. Oxford English Dictionary and several editions of Websters Dictionary define the term as an analog telephone carried over radio signals. The word does not appear in Newtons Telecom Dictionary, 10th edition.
2. ^ One example is the title of a map, "Mobile Communications: Reaching the World by Mobile Telephone Service," (San Francisco: Pacific Telephone and Telegraph Company, March 1983. The map describes IMTS and MTS service in California.
3. ^ Use noted in many cases including on escutcheons and silk-screened face plates on 1960s Motorola products including early HT-200 and Dispatcher-series mobile radios. One specific example is the title on a Special Products service manual, Model T31BAT-3100B-SP3 'Dispatcher' Radiophone 25-54 MC 12 W RF Power 12VDC, State of California Radio Communications System, (Chicago: Motorola Communications Division, 1965). It was also seen on the faceplates of some 1960s Kaar Engineering mobile products. Later HT-200s had the word "Radiophone" replaced by "Handie Talkie FM Radio" on their escutcheon art. The Oxford English Dictionary conflicts with some uses, saying radiophone is interchangeable with radiotelephone. The 10th edition of Newton's Telecom Dictionary says radiophone is an, "obsolete term."