Importance

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Abstract

A method is described with the aid of which messages can be transmitted from batteryless transponders to interrogation devices. The interrogation devices are equipped with a receiving section and a transmitting section and as a request to transmit the message stored therein as reaction to an interrogation command rendered effective in the interrogation device said devices transmit an HF interrogation pulse with predetermined carrier frequency and predetermined carrier duration. In the transponder this HF interrogation pulse is utilized to generate a supply voltage. Each interrogation device checks as reaction to an interrogation command whether its receiving section (14) is receiving a signal with the carrier frequency. If no such signal is being received, the interrogation device transmits the HF interrogation pulse after expiry of a wait time of at least the predetermined message duration whereas, if it is receiving a signal with the carrier frequency, the HF interrogation pulse is not sent until the reception of said signal terminates and at least the wait time has expired or a delay time has passed which is longer than the sum of the predetermined carrier duration and the wait time.

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First Claim