Abstract: A system for testing objects by means of electromagnetic rays is provided that includes at least one test unit which contains at least one radiation source, arranged in a transportable, container-like housing, for producing electromagnetic radiation and at least one detector array associated with the radiation source. The test system contains at least two test units arranged beside one another, each having at least one radiation source, which are arranged in such a way that the object is irradiated from different directions.

Abstract: An interrogation unit which has a control circuit and an RF oscillator is described. The interrogation unit further has a transmitter which receives the output of the RF oscillator and transmits at least one RF interrogation pulse of a first frequency for interrogating the responder unit, causing the responder unit to return read data in the form of a RF response. Also in the interrogation unit is a switch for disabling the output of said transmitter and enabling reception of the RF response upon termination of the RF interrogation signal. The interrogation unit still further has a receiver for receiving the RF response upon termination of the RF interrogation pulse and an interrogation unit demodulator for demodulation of the read data from said RF response.

Abstract: A responder unit for communicating with an interrogator unit which sends an RF interrogation pulse thereto is described. The responder unit includes an energy accumulator which stores the energy contained in the RF interrogation pulse to be used to power the responder unit in the absence of any RF interrogation signal. The responder unit also has a memory for storing read data and a RF threshold detector for detecting termination of the RF interrogation pulse. A RF carrier wave generator under control of the RF threshold detector is operable to activate upon detection of the termination of the RF interrogation pulse. A modulator is provided in the responder unit to modulate the RF carrier with the read data from the memory.

Abstract: A transponder arrangement is described comprising an interrogation unit (10) which sends an RF interrogation pulse to at least one responder unit (12). The responder unit (12) then transmits back data stored therein in the form of a modulated RF carrier to the interrogation unit (10). In the responder unit (12) is an energy accumulator (136) which stores the energy contained in the RF interrogation pulse. The responder unit (12) further contains means (142, 148) which in dependence upon the termination of the reception of the RF interrogation pulse and the presence of a predetermined energy amount in the energy accumulator (126) initiate the excitation of an RF carrier wave generator (130, 132, 134) operating with the frequency contained in the RF interrogation pulse.