Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1990-10-09
1991-09-17
Ng, Jin F.
Communications: electrical
Condition responsive indicating system
Specific condition
340529, 340566, 340572, G08B 2100
Patent
active
050498592
ABSTRACT:
A pool safety alarm system includes a water-activated sonar transmitter adapted to be worn on the body of a non-swimmer for continuously transmitting low frequency audio signals upon immersion of the transmitter. An underwater microphone or hydrophone is located within the pool and is connected to a receiver circuit having a band pass filter connected to a monostable multivibrator for supplying signals to an alarm. Whenever signals within the pass band of the filter are received by the hydrophone, these signals trigger the monostable multivibrator from its stable state to its astable state. The astable state of the multivibrator operates the alarm. When signals within the pass band frequency of the filters are received by the hydrophone from sources other than the water-activated transmitter, such signals typically are momentary or intermittent. These signals cause the monostable multivibrator to be triggered to its astable state and then allowed to time out; so that the alarm produces a short duration alarm signal. Whenever the signals received by the hydrophone are caused by the water-activated transmitter, the signals are continuous; and the monostable multivibrator is continuously retriggered; so that the alarm produces a continuous alarm signal.
REFERENCES:
patent: 3486166 (1969-12-01), Campana et al.
patent: 3810146 (1974-05-01), Lieb
patent: 3925773 (1975-12-01), Green
Karla J. Roffee
Ng Jin F.
Oda C.
Ptak LaValle D.
LandOfFree
Water entry alarm system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Water entry alarm system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water entry alarm system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1919581