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A trunked radio system is a radio system used to maximize available capacity in a two-way radio system, usually UHF. Groups of users are given a logical talkgroup to share for their communications, rather than a dedicated radio frequency. Trunking is used by many government entities to provide two-way communication for fire departments, police and other municipal services, who all share spectrum allocated to a city, county, or other entity. In recent years, radio scanners have been able to follow these systems. This is commonly called trunk tracking, and it was named by Uniden A two-way radio is simply a radio that can both transmit and receive (a transceiver). ...
This article is about the radio frequency. ...
A Talkgroup is a radio channel on a Trunked Radio System. ...
Rough plot of Earths atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation, including radio waves. ...
A government is a body that has the authority to make and the power to enforce laws within a civil, corporate, religious, academic, or other organization or group. ...
Firefighter with an axe A firefighter, sometimes still called a fireman though women have increasingly joined firefighting units, is a person who is trained and equipped to put out fires, rescue people and in some areas provide emergency medical services. ...
Legend: γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves: EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High...
As a general term, Municipal government refers to local government operating at the level of a city, town, or village. ...
Local governments are administrative offices of an area smaller than a state or province. ...
A Scanner is a radio receiver generally capable of picking up AM and FM (and sometimes SSB) radio signals anywhere from 100kHz to 2. ...
Uniden Corportation ) (TYO: 6815 ) is a Japanese company established on February 7, 1966 by its founder Hideo Fujimoto. ...
Principles of Operation
Control channel Users' radios send data packets to a computer, operating on a dedicated frequency——called a Control Channel—to request communication on a specific talk-group. The controller sends a digital signal to all radios monitoring that talkgroup, instructing the radios to automatically switch to the frequency indicated by the system to monitor the transmission. After the user is done speaking, the users' radios return to monitoring the control channel for additional transmissions. A Control Channel is a continuous, dedicated data stream broadcast by a trunked radio system controller for certain systems, such as Motorola and EDACS. Listen to the control channels: Motorola Type II Smartnet/Smartzone Motorola Type I Privacy Plus EDACS Normal EDACS Narrowband Project 25 9600 baud Tetra Category: ...
This arrangement allows multiple groups of users to share a small set of actual radio frequencies without hearing each others' conversations. Trunked systems primarily conserve limited radio frequencies and also provide other advanced features to users.
Comparison with telephone trunking The concept of trunking (resource sharing) is actually quite old, and is taken from telephone company technology and practice. Consider two telco central office exchanges, one in town "A" and the other in adjacent town "B". Each of these central offices has the theoretical capacity to handle ten thousand individual telephone numbers. (Central office "A", with prefix "123", has available 10,000 numbers from 123-0000 to 123-9999; central office "B", with prefix "124", the same.)
How many telephone lines are required to interconnect towns A & B? If all 10,000 subscribers in "A" were to simultaneously call 10,000 subscribers in "B", then 10,000 lines, (in telco parlance "trunk lines", or simply "trunks") would be required between the two towns. However, the odds of that happening are remote. Telephone companies have well-proven formulas which predict the optimal number of trunk lines actually needed, under normal conditions, to interconnect two telephone exchanges.
This concept has simply been applied to radio user groups, to determine the optimal number of channels needed, under normal conditions, to accommodate a given number of users. Note however, the weasel-phrase "under normal conditions". In the event of a widespread emergency such as a major earthquake, many more users than normal will attempt to access both the telephone and radio systems. In both cases once the trunking capacity of the systems is fully used, all subsequent users will receive a busy signal.
In our example of police dispatch, different talk-groups are assigned different system priority levels, sometimes with "preempt" capability, attempting to ensure that communication between critical units is maintained.
Differences from conventional two-way radio "Trunked" radio systems differ from "conventional" radio systems in that a conventional radio system uses a dedicated channel (frequency) for each individual group of users, while "trunking" radio systems use a pool of channels which are available for a great many different groups of users.
For example, if police communications are configured in such a way that twelve conventional channels are required to permit citywide dispatch based upon geographical patrol areas, during periods of slow dispatch activity much of that channel capacity is idle. In a trunked system, the police units in a given geographical area are not assigned a dedicated channel, but instead are members of a talk-group entitled to draw upon the common resources of a pool of channels.
Advantages of trunking Trunked radio takes advantage of the probability that in any given number of user units, not everyone will need channel access at the same time. Therefore with a given number of users, fewer discrete radio channels are required. From another perspective, with a given number of radio channels, a much greater number of user groups can be accommodated. In the example of the police department, this additional capacity could then be used to assign individual talk groups to specialized investigative, traffic control, or special-events groups who might otherwise not have the benefit of individual private communications.
To the user, a trunking radio looks just like an "ordinary" radio: there is a "channel switch" for the user to select the "channel" that they want to use. In reality though, the "Channel switch" is NOT switching channels at all: when changed, it refers to an internal software program which causes a talkgroup affiliation to be broadcast on the control channel. This identifies the specific radio to the system controller as a member of a specific talkgroup, and that radio will then be included in any conversations involving that talkgroup.
This also allows great flexibility in radio usage- the same radio model can be used for many different types of system users (ie Police, Public Works, Animal Control, etc) simply by changing the software programming in the radio itself.
Types of Trunked Radio Systems - Ericsson GE
- Logic Trunked Radio
- Motorola
- MPT-1327
- OpenSky
- APCO Project 25
- SmarTrunk
- TETRA
- TETRAPOL
Amateur and hobbyist
Amateur radio • Citizens' band radio • Family Radio Service
General Mobile Radio Service • Multi-Use Radio Service • PMR446 • UHF CB (Australia) ProVoice is MA/Coms (formerly Ericsson) implementation of IMBE digital modulation for radio communications. ...
EDACS: The Enhanced Digital Access Communication System A radio communications protocol and product family invented in the General Electric Corporation, in the mid 1980s A brilliant young designer, Jeff Childress, created an autonomous radio base-station controller, known as the GETC (General Electric Trunking Card). ...
Audio sample: GE Mark V (file info) — Hear a simulated GE Mark V call as it would sound from a mobile, (version 2). ...
Logic Trunked Radio (LTR) is a system developed in the late 1970s by the E. F. Johnson Company. ...
LTR Standard systems have no dedicated control channel. ...
The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...
LTR Standard and Passport systems are hybrid Trunked Radio Systems that have some LTR Standard talkgroups and some LTR Passport talkgroups. ...
LTR MultiNet Systems are APCO-16 compliant LTR Trunked Radio Systems and thus are mostly found in use as public safety systems. ...
LTR-Net is a type of LTR Trunked Radio System that is a backward compatible with LTR Standard. ...
Type I Type II Type IIi Hybrid Type II SmartZone Type II SmartZone OmniLink Type II VOC Motorola Type I and Type II systems achieve the same thing in a slightly different way. ...
Motorola Type I Is the original type of Motorola a Trunked radio system; it is based on Fleets and Subfleets. ...
Motorola Type II refers to the second generation Motorola Trunked radio systems that replaced fleets and subfleets with the concept of talkgroups and individual radio IDs. ...
A Motorola Type IIi Hybrid system is a type of Trunked radio system where the blocks of the system are Type I Fleets/Subfleets and Type II talkgroups. ...
SmartZone systems are comprised of Type II Smartnet systems that are networked together via microwave or land-line data circuits to provide multi-site wide-area communications. ...
Type II SmartZone OmniLink provides a broad range of robust system features and utilizes a distributed call processing architecture which links up to four multi-site systems together into one seamless network, supporting up to 192 sites. ...
The title of this article is incorrect because of technical limitations. ...
MPT 1327 is a industry standard for trunked radio communications networks. ...
P25 (Project 25) is a standard for digital radio communications for use by federal, state/province and local public safety agencies in North America to enable them to communicate with other agencies and mutual aid response teams in emergencies There are two standards defined defined by the Association for Public...
Look up tetra- in Wiktionary, the free dictionary. ...
The Matra/EADS developed TETRAPOL delivered an operational digital trunked radio system at an early date - delivering to, for example, the French Gendarmerie Nationale in 1988 compared to the first ETSI TETRA system which was installed in 1997. ...
A two-way radio is simply a radio that can both transmit and receive (a transceiver). ...
Ham radio station with modern solid-state transceiver featuring LCD display and DSP capabilities Ham radio station with vintage vacuum tube gear featuring separate transmitter, receiver and power supply Amateur radio, often called Ham radio, is a hobby and public service enjoyed by about 6 million people throughout the world. ...
A typical CB base station. ...
The Family Radio Service is an improved walkie talkie system authorized in the United States. ...
The General Mobile Radio Service (GMRS) is a land-mobile UHF radio service in the United States available for short-distance two-way communications to facilitate the activities of an adult individual who possesses a valid GMRS license, as well his or her immediate family members, including a spouse, children...
The Multi-Use Radio Service (MURS) is a small two-way radio service consisting of five frequencies in the VHF spectrum. ...
Alan 456r PMR446 (Personal Mobile Radio, 446 MHz) is a radio frequency part of the UHF range that is open without licensing for personal usage in most members of the European Union. ...
UHF CB is a licence-free citizens band radio service authorised by the government of Australia in the UHF 477MHz band. ...
Aviation (aeronautical mobile)
Airband • UNICOM Note: This article title may be easily confused with AirBand The airband or air band is the band of frequencies used for radio communication in aviation. ...
To meet Wikipedias quality standards, this article or section may require cleanup. ...
Land-based commercial and government mobile
Business band • Base station • Mobile radio • Radio repeater • Trunked radio system • Walkie talkie The business band is the name used by US scanner hobbyists who listen to Federal Communications Commission licensees using Industrial/Business pool frequencies. ...
Two GSM mobile phone base stations disguised as trees in Dublin, Ireland. ...
It has been suggested that this article or section be merged with Mobile radio telephone. ...
A Radio Repeater is a combination of a radio receiver and a radio transmitter that receives a weak or low-level signal and retransmits it at a higher level or higher power, so that the signal can cover longer distances without degradation. ...
Recreational, toy and amateur radio walkie talkies A walkie-talkie or two-way radio is a hand-held portable, bi-directional radio transceiver. ...
Marine (shipboard)
2182 kHz • Coast radio station • Marine VHF radio • Maritime mobile amateur radio The radio frequency of 2182 kilohertz (kHz) is the international calling and distress frequency for voice maritime communication (radio telephony) on the marine MF bands. ...
Coast radio station is a maritime radio station situated on shore which monitores radio distress frequencies and relays ship-to-ship and ship-to-land communications. ...
Portable VHF radio set Marine VHF radio is installed on all large ships and most motorized small craft. ...
Most countries amateur radio licences allow licensed operators to install and use radio transmission equipment while at sea. ...
Signaling / Selective calling
CTCSS • MDC-1200 • Push to talk • Quik Call I • Selcall • D-STAR 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. ...
In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver. ...
MDC, also known as MDC-1200 and MDC-600, is a low-speed Motorola two-way radio data system using audio frequency shift keying, (AFSK). ...
Push-to-Talk (PTT), also known as Press-to-Transmit, is a method of conversing on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode. ...
Quik-Call I, also known as 2+2, is a selective calling method originally used in one-way paging receivers. ...
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. ...
// D-Star information Digital Smart Technology for Amateur Radio D-Star Radio is a digital HAM radio. ...
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