| 摘要 |
<p>A detection/identification apparatus for detecting the presence of an item at a particular point in space includes means (14, 16) for establishing an alternating electromagnetic field in a volume of space containing the point using a field excitation signal, means (28a, 28b) for defining a field vector representing the electromagnetic field relative to a base vector representing the excitation signal and means (32) responsive to the defining means for determining whether the field vector is outside of a range of vectorial values wherein such determination is indicative of the presence of the item at the particular point. The apparatus may also be used to distinguish between and thereby identify several different items, if desired.</p> |
