Alarm arrangement

An alarm arrangement for causing an alarm signal to be emitted in response to a person being monitored when entering a water zone, the arrangement including at least one transportable electronic transmitter unit (16) and at least one electronic receiver unit (18), and being characterized thereby that the transportable electronic transmitter unit (16) has attachment means (100) for associating it with a user's body, and a housing (20) containing operatively connected electronic circuitry components, and having water activated electrical contacts (24, 26) outside the housing (20) for causing energization of the electronic circuitry when coming into contact with water so as to emit a continuous ultrasonic operative signal when such a person wearing the transmitter unit (16) enters into water in a water zone (10) being monitored;

• and the receiver unit (18) having a housing (36) containing operatively connected electronic circuitry components, and having water activated electrical contacts (54, 56) outside the housing (36) for causing energization of the electronic circuitry when coming into contact with water, and being adapted to detect any operative signal at a preselected frequency from the transmitter unit (16) when the transmitter unit (16) comes into contact with water in the water zone (10) being monitored, and the receiver unit (18) being adapted thereupon to emit a suitable alarm signal.