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CRYSTAL COMMUNICATION SDN BHD (306943 T) Homepage |
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Smart card
Specification 1/ Smart card Crystal Contact less Smart Card 1/ Crystal 1 = 125 kHz ( Long Range 0 – 1 m ) 2/ Crystal 2 = 13.56 MHz ( Proximity 0 – 10 cm )
Smart Card Technology CMOS - EEPROM Micro controller Support high level language and Windows based (example C language)
Technology provider 1/ High data security - selectable data encryption and mutual authentication 2/ Multi transponder operation - fast and reliable anti-collision algorithm 3/ Wide operating range - reading and writing distance up to 1 meter 4/ Flexibility - multi mode operation (emulation of standard read only modes)
ADVANTAGES 1/ High user convenience, easy handling 2/ Fast and secure operation 3/ High reliability, maintenance free components 4/ Installed reader base (multi-mode tag) Industry standard frequency
APPLICATIONS 1/ Access Control & Security - Hands-free Access Control - Time and Attendance Systems - Electronic Keys - Ticketing - Gaming Chips
2/ Logistic & Industrial - Gas Cylinders - Logistics - Automation - Laundry - Asset Tracking
3/ Immobilizer - Car Immobilizer
4/ Identifications (ID) - Animal ID
Theory of Operation The Contactless smart card is a read/write transponder, which is inductively linked to a base station. For reading the transponder, the base station generates an Electro-magnetic field. The transponder modulates the field by switching between two different load impedance. The base station demodulates the field modulation of the transponder in order to recover the information signal. For demodulation an envelope demodulator is used. Both the base station antenna and the transponder antenna consist of resonant circuits whose nominal resonant frequencies equal the carrier center frequency of 125kHz. Manufacturing distribution and temperature variation lead to a tolerance field for both resonant frequencies. Viewing on the system under tolerance conditions results in a change of modulation level at the modulator input. Certain deviations in resonant frequency of either antenna or transponder may result in no or reverse amplitude modulation, although the transponder is supplied with enough energy and modulates. The areas of no amplitude modulation are called zero lines. With even larger deviations in resonant frequency, the transponder is beyond the energy limit and stops working. In order to understand this phenomenon an equivalent circuit is developed including the base station antenna and the inductively coupled transponder. From the equivalent circuit, equations are derived and included in a simulation program. The simulation program varies the resonant frequencies of both resonant circuits and circulates for each variation the amplitude difference voltage for the two-transponder states at the modulator input. Thus, it shows the performance of envelope demodulator with given sensitivity.
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