| 摘要 |
<p>An antitheft system for a motor vehicle includes a transponder having a charging capacitor which is wirelessly charged by energy signals from a transceiver. The level of the energy being transmitted depends on the quality of an inductive transmission between the transponder and the transceiver. Too little energy is transmitted if the exciting frequency of a transceiver oscillating circuit does not correspond to its resonant frequency due to component tolerances. In order to ensure that the charging capacitor is always quickly and properly charged, the exciting frequency is varied within a predetermined frequency range during a charging phase so that it passes in the vicinity of the resonant frequency at least once.</p> |
