Radio alarm system
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United States of America Patent
Stats
-
Sep 15, 1992
Grant Date -
N/A
app pub date -
Dec 20, 1990
filing date -
Dec 28, 1989
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A radio alarm system for detecting abnormalities such as a fire having a central unit which is adapted to receive and decode the radio signal transmitted from each terminal device and to give an alarm and a plurality of terminal devices which is connected to a detector for detecting an abnormal state and is adapted to transmit information in the form of a radio signal based on an abnormality detection signal from the respective associated detector. And delay times which vary from terminal device to terminal device are set, and the selection of a free channel for transmission is effected in each terminal device by performing carrier sensing over a delay time peculiar to that terminal device. Each of the terminal devices is equipped with a channel setting means which successively performs, when transmitting information, carrier sensing on a plurality of transmission channels previously allocated the terminal device, in a previously determined order, thereby selecting a free channel which is not being used by an other terminal device.
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