Closed-circuit radio
A closed-circuit radio is similar to traditional radio communication, though its signal is sent via pre-laid speaker wires or utility lines. It has a very limited range, typically within a building or a college campus.
- An existing PA System may be used to send the audio signal. This method is typically applied in schools, such as by permitting students to use a central microphone to deliver daily announcements.[1]
- Existing power lines, telephone lines, pipes, etc. can transmit a carrier current. Radio receivers at close range may then tune to the signal emitted from the utility line.[2][3][4][5][6][7]
References
[edit]- ↑ Allen, Bob. "Radio Industry: closed circuit radio station, school radio station, college dormitories". AllExperts. 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
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