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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 say ... [...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. 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. Som ... 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 subscriber units know that the system is there. The idle data burst can be turned off if desired by the system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trunked Radio Systems
A trunked radio system 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-talk'. ... [...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] |
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. 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 competition dealt with fault tolerance by means of the "brute force and ignorance" approach, deploying double the hardware for their controllers, and interconnecting them with massive and problematic relay banks . 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-t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Rafael, California
San Rafael ( ; Spanish language, Spanish for "Raphael (archangel), St. Raphael", ) is a city and the county seat of Marin County, California, 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 downt ... [...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 c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal Strength
In telecommunications, particularly in radio frequency engineering, signal strength refers to 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 expressed 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Base Station
Base station (or base radio station) is – according to the International Telecommunication Union's (ITU) Radio Regulations (RR) – a "land station in the land mobile service." 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 fleet, the base of a TETRA network as used by government and emergency services or a CB shack. Land s ... [...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 and are capable of communicating with each other, they exhibit ''syntactic interoperability''. XML and SQL are examples of common data formats and protocols. Lower-level data formats also contribute to syntactic interoperability, ensuring that alphabetical characters are stored in the same ASCII or a Unicode format in all the commun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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