| 摘要 |
<p>The invention relates to an electronic article surveillance system which in pulses emits an electromagnetic field, and in monitoring intervals between the pulses receives reply signals from alarm labels within the surveillance area of the system. An incoming signal is sampled (11) in the system. The zero crossings of the sampled signals are identified, and the phase positions thereof are compared (19) with corresponding phase positions of zero crossings of an incoming signal, received and sampled in a previous monitoring interval. If these phase positions agree sufficiently well, an alarm can be initiated (25).</p> |
