| 摘要 |
<p>A method is provided for remote detection of objects, each object being provided with a sensor comprising at least two magnetic elements arranged in a predetermined mutual relationship representing an identity of the sensor. Electomagnetic signals are generated for exciting the sensor elements to produce electromagnetic reply signals. An amplitude of the electromagnetic reply signal from each sensor element is modulated by a first magnetic field having a magnitude-variant and a magnitude-invariant component. A second magnetic field is generated with rotating field vector. A frequency shift is detected in a component of said reply signal, when a magnitude-invariant component of said second magnetic field balances the magnitude-invariant component of said first magnetic field, wherein the respective sensor element is momentarily exposed to a resulting magnetic field with essentially no magnitude-invariant component. An orientation of the respective sensor element is determined from the orientation of the magnitude-invariant component of said second magnetic field, when said frequency shift occurs.</p> |
