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LTR Passport
PassPort is a type of LTR Trunked radio system designed by Trident Micro Systems, which consists of multiple radio repeater sites linked together to form a wide-area radio dispatch network. Purpose Radio signals have a limitations due to distance and terrain. If two radios are far apart, or there is a mountain in the way, they will not be able to communicate. To alleviate this, radio repeaters are installed on mountaintops to repeat the signal from one radio to another, or group of others. This is a standard repeater site. The signal is received by the repeater from the originating radio and re-broadcast so the receiving radio(s) can receive the radio signal. A repeater site gives approximately a 50-mile radius of coverage. Trunk ed radio is a method of using a bank of channels (frequencies) to repeat for multiple "Talk Groups" or fleet of radios. Many Talk Groups can share the channels, without hearing each other's conversation. A Passport system combines both of these technologi ... [...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 System
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] |
Trident Microsystems
Trident Microsystems was a fabless semiconductor company that in the 1990s, it became a well-known supplier of integrated circuits (commonly called "chips") for video display controllers used in video cards and on motherboards for desktop PCs and laptops. In 2003, it transformed itself into being a supplier of display processors for digital televisions (primarily LCD TVs) starting from 2005, at a time when the global LCD TV market started showing strong growth. It filed for bankruptcy protection in January 2012 and the delisting of its common stock from the NASDAQ stock market was announced shortly thereafter. History PC graphics Established in 1987, Trident gained a reputation for selling inexpensive (for the time) but slow SVGA components. Many OEMs built add-in-boards using Trident VGA chipsets. As the PC graphics market shifted from simple framebuffer displays (basic VGA color monitor and later multi-resolution SVGA output) to more advanced 2D hardware accelerat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trunked Radio Site
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] |
Radio Scanner
A scanner (also referred to as a radio scanner) is a radio receiver that can automatically tune, or ''scan'', two or more discrete frequencies, stopping when it finds a signal on one of them and then continuing to scan other frequencies when the initial transmission ceases. The term ''scanner'' generally refers to a communications receiver that is primarily intended for monitoring VHF and UHF landmobile radio systems, as opposed to, for instance, a receiver used to monitor international shortwave transmissions. More often than not, these scanners can also tune to different types of modulation as well ( AM, FM, WFM, etc.). Early scanners were slow, bulky, and expensive. Today, modern microprocessors have enabled scanners to store thousands of channels and monitor hundreds of channels per second. Recent models can follow trunked radio systems and decode APCO-P25 digital transmissions. Both hand held and desktop models are available. Scanners are often used to monitor police, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
