Identification system having a plurality of devices for reading, writing

Abstract

The identification system operates by the contactless, inductive transmission of information via oscillatory circuits coupled by an electromagnetic field. Excitation is produced by pulses representing the information; the pulse response is utilized. The associated apparatus has one or more pairs of oscillatory circuits (A1/B1;A2/B2;A3/B3) and means (21, 22, 23) for processing the pulse response. A position recognition process transmits test information which is used for the sequential short-circuiting of an oscillatory circuit on the receiver side. This oscillatory circuit behaves like a damped/undamped body as a function of the test function. The partner oscillatory circuit on the transmitter side is excited at, for example, twice the frequency of the test frequency and its pulse response contains the test function through the defined damping behaviour. If the test function is again recognized as a result, the connection is correct and write or read operation is released. If the switch is operated not with a test function, but with a switching sequence of electric values representing data from a store, excitation produced in the partner oscillatory circuit by an interrogation coil can produce a pulse response which contains the data from the store.