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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] |
LTR Standard
Within radio technology, LTR (Logic Trunked Radio) Standard systems have no dedicated control channel. All control data is sent as subaudible data along with voice transmissions. Systems can have any number of channels from 1 through a maximum of 20. Each channel in the system is assigned a unique number (01 through 20) and these need not be sequentially assigned. Each subscriber radio must be programmed with all channels in the system in proper logical channel order (the same requirement as EDACS systems). LTR Standard Talkgroups are written in the format A-HH-GGG. * "A" is the area code and is either 0 or 1. The area code is the same for all Talkgroups in a given system and is arbitrarily chosen by the system operator; the most common use is to simply distinguish between Talkgroups on multiple systems. * "HH" is the home repeater number and has twenty possible values, 01 through 20. Talkgroups usually use their home repeater by default, unless the repeater is already in us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 technolog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |