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LTR MultiNet
LTR MultiNet Systems are APCO-16 compliant LTR Trunked Radio Systems and thus are mostly found in use as public safety systems. LTR MultiNet systems usually have one or more "status channels" that act like a control channel in a Motorola or EDACS system, however these channels can also carry voice transmissions simultaneously. APCO 16 compliance Some trunked systems queue calls if a user's attempt to transmit gets a busy signal. In other words, if someone presses their push-to-talk button and all trunked radio system channels are busy, some systems will wait-list users in the same order as their busy signals occur. When a channel becomes available, the system notifies the user. There is disagreement about MultiNet's ability to queue calls when all channels are busy. Usually, the control channel is the path allowing wait-listed users to get in line. One publication says MultiNet communicates using low baud rate data multiplexed under voice if all channels are busy. One report sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
APCO-16
In telecommunications, APCO-16, (sometimes APCO Project 16 or Project 16) is a US standard for the characteristics and capabilities of public safety trunked radio systems. The standard development effort was started in the 1970s by the APCO, a trade association of mostly police and fire service providers. The program was funded by the Law Enforcement Assistance Administration (LEAA), a part of the US Department of Justice."4.2.1 APCO Project 16," ''Arizona Phase II Final Report: Statewide Radio Interoperability Needs Assessment,'' (Phoenix, Arizona: Macro Corporation and The State of Arizona, 2004), pp. 42-43."Review of the APCO 'Project 16' Report," ''The California Highway Patrol Communications Technology Research Project on 800 MHz'', 80-C477, (Sacramento, California: Department of General Services, Communications Technology Division, 1982,) pp. I-3 - I-9. Details APCO-16 describes such characteristics and capabilities as: * channel access times * automated priority recogni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logic Trunked Radio
Logic Trunked Radio (LTR) is a radio system developed in the late 1970s by the E. F. Johnson Company. LTR is distinguished from some other common trunked radio systems in that it does not have a dedicated control channel. LTR systems are limited to 20 channels (repeaters) per site and each site stands alone (not linked). is Each repeater In telecommunications, a repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Some ... has its own controller and all of these controllers are coordinated together. Even though each controller monitors its own channel, one of the channel controllers is assigned to be a master and all the other controllers report to it. Typically on LTR systems, each of these controllers periodically sends out a data burst (approximately every 10 seconds on LTR Standard systems) so that the subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trunked Radio Systems
A Trunked Radio System (TRS) is a two-way radio system that uses a control channel to automatically assign frequency channels to groups of user radios. In a traditional half-duplex land mobile radio system a group of users (a ''talkgroup'') with mobile and portable two-way radios communicate over a single shared radio channel, with one user at a time talking. These systems typically have access to multiple channels, up to 40-60, so multiple groups in the same area can communicate simultaneously. In a conventional (non-trunked) system, channel selection is done manually; before use, the group must decide which channel to use, and manually switch all the radios to that channel. This is an inefficient use of scarce radio channel resources because the user group must have exclusive use of their channel regardless of how much or how little they are transmitting. There is also nothing to prevent multiple groups in the same area from choosing the same channel, causing conflicts and 'cross ... [...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] |
EDACS
The Enhanced Digital Access Communication System (EDACS) is a radio communications protocol and product family invented in the General Electric Corporation in the mid 1980s. The rights were eventually bought by Harris Corporation, which eventually stopped manufacturing these devices in 2012, and ended all service in 2017. History A young designer, Jeff Childress, created an autonomous radio base-station controller, known as the GETC (General Electric Trunking Card). The GETC was a general-purpose controller with input/output optimized for radio system applications. Childress and the team demonstrated that a smart controller could be adapted to a variety of applications, but his interest was really in fault tolerance. The EDACS system architecture supported large communications footprints. By making the GETC's "trunk" among themselves, one GETC per channel, the system was designed to be inherently fault-tolerant. This provided substantial hardware reductions, and the re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Rafael, California
San Rafael ( ; Spanish language, Spanish for "Raphael (archangel), St. Raphael", ) is a city in and the county seat of Marin County, California, United States. The city is located in the North Bay (San Francisco Bay Area), North Bay region of the San Francisco Bay Area. As of the 2020 United States census, 2020 U.S. census, the city's population was 61,271, up from 57,713 in 2010. San Rafael was founded by the Spanish in 1817, when Vicente Francisco de Sarría established Mission San Rafael Arcángel, initially as an Asistencias, ''asistencia'' (sub-mission). San Rafael Arcángel was upgraded to full Spanish missions in California, mission status in 1822, a month before Alta California declared independence from Spain as part of First Mexican Empire, Mexico. Following the American Conquest of California, the community of San Rafael incorporated as a city in 1874. History San Rafael was once the site of several Coast Miwok villages: ''Awani-wi'', near downtown San Rafael, ''Ewu'' ... [...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] |
Signal Strength
In telecommunications, particularly in radio frequency engineering, signal strength is the transmitter power output as received by a reference antenna at a distance from the transmitting antenna. High-powered transmissions, such as those used in broadcasting, are measured in dB- millivolts per metre (dBmV/m). For very low-power systems, such as mobile phones, signal strength is usually expressed in dB- microvolts per metre (dBμV/m) or in decibels above a reference level of one milliwatt ( dBm). In broadcasting terminology, 1 mV/m is 1000 μV/m or 60 dBμ (often written dBu). Examples *100 dBμ or 100 mV/m: blanketing interference may occur on some receivers *60 dBμ or 1.0 mV/m: frequently considered the edge of a radio station's protected area in North America *40 dBμ or 0.1 mV/m: the minimum strength at which a station can be received with acceptable quality on most receivers Relationship to average radiated power The electric field strength at a specific point ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Falsing
In telecommunications, falsing is a signaling error condition when a signal decoder detects a valid input although the implied protocol function was not intended. This is also known as a false decode. Other forms are referred to as talk-off. Signal detection Signal decoders used in communication systems, such as telephony and two-way radio systems, detect communication protocol states by recognizing a variety of electrical, optical, or acoustic conditions. Misinterpretation of those conditions leads to communication errors. Proper detection of signaling is a compromise between acceptable error rates and cost of implementation. The engineering problem is to produce the simplest circuit that works reliably. A decoder generally tries to filter audio input to strip off every audio component except a sought-after, specific tone. In part, a decoder is a narrow bandpass filter. A signal that gets through the narrow filter is rectified into a DC voltage which is used to switch something ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Station
Base station (or base radio station, BS) is – according to the International Telecommunication Union's (ITU) Radio Regulations (RR) – a " land station in the land mobile service." A base station is called '' node B'' in 3G, '' eNB'' in LTE ( 4G), and '' gNB'' in 5G. The term is used in the context of mobile telephony, wireless computer networking and other wireless communications and in land surveying. In surveying, it is a GPS receiver at a known position, while in wireless communications it is a transceiver connecting a number of other devices to one another and/or to a wider area. In mobile telephony, it provides the connection between mobile phones and the wider telephone network. In a computer network, it is a transceiver acting as a switch for computers in the network, possibly connecting them to a/another local area network and/or the Internet. In traditional wireless communications, it can refer to the hub of a dispatch fleet such as a taxi or delivery fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interoperability
Interoperability is a characteristic of a product or system to work with other products or systems. While the term was initially defined for information technology or systems engineering services to allow for information exchange, a broader definition takes into account social, political, and organizational factors that impact system-to-system performance. Types of interoperability include syntactic interoperability, where two systems can communicate with each other, and cross-domain interoperability, where multiple organizations work together and exchange information. Types If two or more systems use common data formats and communication protocols then they are capable of communicating with each other and they exhibit ''syntactic interoperability''. XML and SQL are examples of common data formats and protocols. Low-level data formats also contribute to syntactic interoperability, ensuring that alphabetical characters are stored in the same ASCII or a Unicode format in all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
