Free running RF identification system with increasing average inter transmission intervals

摘要

An RF electronic identification system 10 is disclosed and claimed. The system includes a reader 12 and a plurality of transponders 14.1 to 14.n. When energized by an interrogation signal from the reader, each transponder automatically responds by repeatedly retransmitting a signal burst including identification code data associated with the relevant transponder. Each transponder includes circuitry 34 for generating random inter-transmission intervals for separating any two consecutive signal bursts and a controller 42 for the generation circuitry, to cause an average value of the inter-transmission intervals over a period of time to vary, preferably to increase. This feature enhances the probability and speed of reading a transponder population of almost any size.