The card reader emits electromagnetic waves at a fixed frequency, and the frequency is generally 13.56 MHz. When the proximity card enters the wireless access control system map in the electromagnetic radiation range of the card reader, the coil on the induction card is triggered to generate current and trigger on the induction card. The antenna transmits a signal to the card reader, the signal carries card information, the card reader converts the level signal into a digital serial number, transmits it to the local controller, and the local controller uploads the information to the upper controller, and finally uploads it to the controller. The access server, the access control server compares the card number with the information in the database to obtain all the card information.
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