| 摘要 |
FIELD: physics.SUBSTANCE: security alarm comprises four sensitive elements in the form of cable sections and a signal processing unit for processing signals from the sensitive elements, each being a cable section with a length of up to 250 m which ends with an end sleeve, in which there is a 4.7 megaohm resistor, which is connected in an electrical circuit between centre conductors and the cable sheath. The processing unit comprises two low frequency value amplification modules, two high frequency value amplification modules, two bias supply modules for the amplifiers, a supply conversion module and a decision module. The alarm is also provided with a power supply and communication unit, having a battery, a radio modem, a charge controller and a solar module. The output of the sensitive element is connected to a low frequency value amplification module or a high frequency value amplification module, the outputs of which are connected to the decision module, which is bidirectionally connected to the radio modem. Inputs of the bias supply modules for the amplifiers are connected to the supply conversion module, and the outputs thereof are connected to the low frequency value amplification modules and the high frequency value amplification modules.EFFECT: low power consumption and longer operational life of the alarm.3 dwg |
