Who knows what is the principle of inductive hotel magnetic card lock?

The electrical part of the card consists of antenna and control part CPU (encapsulated by PVC). The antenna of the card is only packaged in a card with several groups of winding coils. There is a high-speed (baud rate 106KB) interface in the card. 16 the card reader of the control unit sends a set of electromagnetic waves to the card. There is an LC series resonant circuit in the card, and its frequency is the same as that emitted by the card reader. Under the excitation of electromagnetic waves, the LC resonant circuit produces * * vibration, which makes the capacitor charged. At the other end of the capacitor, an electronic pump with unidirectional conduction is connected to send the charge in the capacitor to another capacitor for storage. When the accumulated charge reaches a certain voltage, this capacitor can be used as a power supply to provide working voltage for other circuits, transmit data in the card or receive data from the card reader.