Security system

摘要

The keyless security locking system (14) has a battery with its terminals (-V BATT,+V BATT) connected to two antenna leads (16,18). The control circuit (10) contains a microcontroller (34) and a switching circuit (28) with transistor switches (50,52) connected to a transmission antenna (12). The circuit also contains a high frequency receiver (26). The first antenna lead is connected to the first input (22) of the receiver and the second antenna lead is connected to the second input (24) via a high-pass or bandpass filter. The switching circuit monitors the switching state of the antenna using a DC voltage or a DC current.