FIELD: physics, alarm.
SUBSTANCE: invention is used in security equipment to detect intrusion into the premises. The method is based on recording alterations in the parameters of the acoustic signal outspreading inside the secured premises; the acoustic signal in the secured premises is generated as short pulses with their duration being small in comparison to the releasing time of acoustic and electrical transitions and with their repetition interval being a fortiori greater than the releasing time of the above transitions. During the pulse action an electronic part of the acoustic unit is switched off by an electronic key in order to prevent intense acoustic signal from blocking it before receiving a far weaker response signal.
EFFECT: increasing the method efficiency and trustworthiness, increasing response speed and thermal noise immunity level.
1 dwg
