“Closed-circuit radio”的意思、由来-开放百科全书

词条

Closed-circuit radio

释义

References

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^[1]
By using existing power lines, telephones lines, pipes, etc. to transmit a carrier current^[2]

References

1. ^Radio Industry: closed circuit radio station, school radio station, college dormitories
2. ^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 }}

1 : Radio communications

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