Introduction to Proximity Cards
– Proximity cards are contactless smart cards used for access control and identification.
– They can be read without inserting them into a reader device.
– Proximity cards are part of the contactless card technologies.
– They have a read range of up to 50cm (20in), unlike contactless smartcards.
– Proximity cards can hold data like the card serial number and can be used for various applications.
Types of Proximity Cards
– Passive cards: They are powered by radio frequency signals from the reader device and have a limited range.
– Active cards: They are powered by an internal lithium battery and have a greater range.
– Passive 125kHz cards are widely used for access control doors.
– Contactless smartcards, a version of passive cards, are used for other applications like library cards and contactless payment systems.
– Active 125kHz prox cards and UHF smart cards have even greater ranges and are used for specific applications.
Method of Operation
– Proximity cards communicate with reader units through radio frequency fields.
– Passive cards have an antenna coil, capacitor, and integrated circuit (IC) sealed inside.
– The reader unit continuously transmits a radio frequency field.
– When the card is within range, the antenna coil and capacitor absorb energy from the field.
– The integrated circuit sends its ID number or other data back to the reader unit.
Standards for Proximity Cards
– Proximity cards are proprietary, meaning there is no compatibility between different brands.
– Contactless smartcards are covered by ISO/IEC 14443 and/or ISO/IEC 15693 standards.
– ISO/IEC 14443 and ISO/IEC 15693 define different types of cards with different communication protocols.
– ISO/IEC 15693 (vicinity card) works up to a longer range than ISO/IEC 14443.
– Microprocessor-based cards are required for full implementation of ISO standards.
125 kHz Readers and Formats
– Card readers communicate using various protocols like Wiegand, Clock and Data, or OSDP.
– Card formats have increased in bit size to provide unique numbers.
– Facility or site codes are used to differentiate cards within the same company.
– Smartcards follow an internationally harmonized numbering system allocated by NEN.
– The bit size and numbering system ensure unique identification and compatibility.Sources: https://en.wikipedia.org/wiki/Proximity_card
