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Closed-circuit radio 
Summary
A closed-circuit radio is a radio that emits over a very small range, typically a college campus. This system can be achieved from two ways:
- By tying into the PA System[clarification needed][1]
- By using existing power lines, telephones lines, pipes, etc. to transmit a carrier current[clarification needed][2][3][4][5][6][7]
References edit
- ^ "Radio Industry: closed circuit radio station, school radio station, college dormitories". Archived from the original on 2012-09-27. Retrieved 2011-04-16.
- ^ The early days of armed forces radio Archived 2011-07-21 at the Wayback Machine
- ^ Closed-circuit communications signal distribution system
- ^ Radio behind bars – The Polish case
- ^ Closed-circuit Radio Relays Game
- ^ College Closed-circuit Radio Station Gets New, More Powerful Transmitter
- ^ Closed-circuit Radio Network in Homes Seen