Communications: electrical – Systems – Call station
Patent
1975-11-10
1977-04-26
Caldwell, John W.
Communications: electrical
Systems
Call station
340167R, 340150, 340413, 325 58, 178 691, G08B 108
Patent
active
040204774
ABSTRACT:
A radio central station alarm system including a central station and a plurality of remote stations for transmitting alarm signals to the central station by means of radio signals. Alarm signals are transmitted repeatedly in a sequence which reduces the probability that signals transmitted by one remote station will be completely obscured by signals transmitted by other remote stations. A pulse position modulation binary data format is used which simplifies both remote and central station apparatus and facilitates error-free data transmission. The central station is highly immune to noise and performs a number of tests on received data signals to reduce or eliminate false or erroneous alarm indications. Latching alarm sensor circuits are provided for use at the remote stations to insure that all transmission sequences are completed. Protective circuits are provided for disabling any remote station which transmits signals for longer than a maximum allowable transmission interval.
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American District Telegraph Company
Caldwell John W.
Crosland Donnie L.
Jackson Robert R.
Smith Charles B.
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