Method of transmitting messages with predetermined message duration from batteryless transponders to interrogation devices

Claim 1

Method of transmitting messages with predetermined mess­age duration from batteryless transponders to interrogation devices which are equipped with a receiving section and a transmitting section and which transmit to the transponders as request for transmission of the message stored therein as reaction to an interrogation command rendered effective in the interrogation device an HF interrogation pulse of predetermined carrier frequency and predetermined carrier duration which is utilized in the transponder simultaneously for generating a supply voltage, characterized in that each interrogation device as a reaction to an interrogation command checks whether its receiving section (14) is receiv­ing a signal with the carrier frequency, that then, if no such signal is being received, it transmits the HF interro­gation pulse after expiry of a wait time of at least the predetermined message duration whereas when such a signal is being received it does not transmit the HF interrogation pulse until the reception of said signal terminates and at least the wait time has expired or a delay time has expired which is longer than the sum of the predetermined carrier duration and the wait time.