CDVI Pass is based on an active tag equipped with a radio double technology, passive (at 125 KHz) and active (at 433,92 MHz).  The active tag stays always in stand-by: when it arrives inside the aerial detection zone, it wakes-up and starts transmitting at 433,93 MHz.  In this way its battery consumption is highly limited. If, whilst remaining in the detection zone, it  does not move, the internal motion sensor sets it in stand-by.