As the antenna passes over the transponder, it energizes the latter with an energy field of 13.56 MHz. The transponder returns its code through frequency modulation to the antenna. An additional coil generates the positioning pulse. The interpreter which is integrated within the antenna decodes the transponder code. A normal reading cycle, including all security checks, is approximately 1 ms.
The system’s operability is guaranteed through fluid, gaseous as well as solid metal-free materials. However, if mounted directly on or within metal, the transponder’s reading distance is influenced. The Read-Write Transponders are equipped with an EEPROM in which the code is stored. The EEPROM may be rewritten up to more than 100,000 times. It has 32 bit available for user data.