| 摘要 |
A method for reading a transponder for mobile units, which units may be road-borne vehicles or rail-borne vehicles such as train sets, goods wagons, lorries and freight containers, where a transponder (1, 6, 7, 15) is mounted on the mobile unit and where at least one fixed deployed communicator (8, 9, 16) is present arranged to read the relevant transponder (1, 6, 7, 15) by transmitting an enquiry signal to the transponder, which enquiry signal is reflected by the transponder, whereby the reflected signal is received by the communicator (8, 9, 16). The invention is characterised in that the said communicator (8, 9, 16), or communicators, is, or are, located such that the communicator forms an angle (V) with the direction of travel of the transponder (1, 6, 7, 15), in that an enquiry signal with a constant frequency is emitted by the communicator (8, 9, 16), in that a number of reflections of the enquiry signal from the surfaces (29) of the mobile unit (12) that surrounds the transponder (15) are caused to be received by the communicator (16), in that a frequency analysis is caused to be carried out in an analysis circuit (25) with respect to whether the reflections received have a higher or a lower frequency than the frequency of the enquiry signal, whereby the said analysis circuit (25) is caused to detect whether the mobile unit (12) is receding from or approaching the communicator (16). |
