Closed-circuit radio
{{Short description|Radio that emits over a very small range}}
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{{clarify|Most PA systems use cable transmission, not radio transmission, sow how is this a radio system, and if radio transmission is used, how is it closed circuit?|date=July 2023}}{{Cite web |url=http://en.allexperts.com/q/Radio-Industry-2499/2008/4/closed-circuit-radio-station.htm |title=Radio Industry: closed circuit radio station, school radio station, college dormitories |access-date=2011-04-16 |archive-url=https://web.archive.org/web/20120927045801/http://en.allexperts.com/q/Radio-Industry-2499/2008/4/closed-circuit-radio-station.htm |archive-date=2012-09-27 |url-status=dead }}
- By using existing power lines, telephones lines, pipes, etc. to transmit a carrier current{{clarify|How is this a radio if it does not use radio waves for signal transmission?|date=July 2023}}[http://afrts.dodmedia.osd.mil/heritage/first50/Chapter%205_The%20Early%20Days%20of%20Armed%20Forces%20Radio.pdf The early days of armed forces radio] {{webarchive|url=https://web.archive.org/web/20110721165943/http://afrts.dodmedia.osd.mil/heritage/first50/Chapter%205_The%20Early%20Days%20of%20Armed%20Forces%20Radio.pdf |date=2011-07-21 }}[https://patents.google.com/patent/US2996580A/en Closed-circuit communications signal distribution system][https://www.ingentaconnect.com/content/intellect/rj/2013/00000011/00000002/art00003 Radio behind bars – The Polish case][https://www.newspapers.com/clip/49788672/closed-circuit-radio-1-wikipedia/ Closed-circuit Radio Relays Game][https://www.newspapers.com/clip/49788831/closed-circuit-radio-2-wikipedia/ College Closed-circuit Radio Station Gets New, More Powerful Transmitter][https://www.newspapers.com/clip/49789188/closed-circuit-radio-3-wikipedia/ Closed-circuit Radio Network in Homes Seen]