Switched Combining Two-way Radio Example
In land-mobile radio, where vehicle-mounted and hand-held radios communicate with a base station radio over a single frequency, space diversity is achieved by having several receivers at different sites. Diversity combining, or voting, in two-way radio systems is a method for improving talk-back range from walkie-talkie and vehicular mobile radios.
The receivers are connected to a device referred to as a voting comparator or voter.
The voting comparator performs an evaluation of all received signals and picks the most usable received signal. In repeater systems, the voted signal is retransmitted. In simplex systems, it goes to the console speaker at the base station. Audio from a receiver that is not voted is ignored. Voting comparators in analog FM systems can switch between receivers in tenths- or hundredths-of-a-second, (faster than one syllable). So long as an intelligible signal gets to a single receiver in the system, the repeated audio, or audio sent to the console speaker, would be intelligible.
In this arrangement, receivers at remote sites are connected to the voting comparator by private telephone lines, a channel in a D4 channel bank on a DS1, or an analog microwave baseband channel.
Read more about this topic: Diversity Combining
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