RADIOWELLEN-ANTWORTSENDERVORRICHTUNG IN EINEM ANTWORTSENDERSYSTEM

摘要

In a radio transponder apparatus a rectifier 11 converts a received radio wave into a DC power for a response logic circuit 12, a voltage comparator 21 compares an output voltage from the rectifier with a predetermined minimum operating voltage L for controlling a circuit 20 which activates one of components which constitute the radio transponder apparatus to start a response operation when the output voltage from the rectifier is not less than the minimum operating voltage. The circuit 20 may control the supply of DC power to circuit 12, the supply of response signal from circuit 12 to transmitter 15 or the supply of interrogation signals from receiver 14 to circuit 12. The output of comparator 21 may actuate a display 22 or an alarm. The apparatus avoids erroneous operation when the transponder is located beyond an optimal distance from an interrogating apparatus. The transponder may be an ID card or a product on assembly line. <IMAGE>