| 摘要 |
The system is intended for monitoring objects or persons in a predetermined close-in region situated around a user carrying out the said monitoring. It comprises a portable, self-contained control box (100) carried by the user with a self-contained power supply source, a frequency-modulated transmitter/receiver (111, 112), a programmable coder/decoder (110), a generator (120) of periodic signals, a delaying circuit (120) and local alarm means (190). The system further comprises a self-contained, portable, detection box arranged on the object or the person to be monitored and comprising a self-contained power supply source, a frequency-modulated transmitter/receiver, a programmable coder/decoder, a generator of periodic signals, a delaying circuit and local alarm means. The self-contained, portable control box (100) further comprises means for allowing triggering of the local alarm means (190) only when the level of the coded signal transmitted by the transmitter/receiver (211, 212) of the self-contained portable detection box and received by the transmitter/receiver (111, 112) has fallen below a given threshold for a time longer than a predetermined duration. <IMAGE>
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