Anti-shoplifting security system
作者： Jon Neal Weaver
DOI:
关键词: Analog transmission 、 Noise (radio) 、 Electromagnetic field 、 Radio transmitter design 、 Materials science 、 Pulse-density modulation 、 Harmonics 、 Modulation 、 Electrical engineering 、 Acoustics 、 Amplitude modulation
摘要: This invention relates to detecting the presence of a soft magnetic marker in an interrogation zone. A low frequency electromagnetic field is produced utilizing dual generators causing produce phase shift modulation transmission harmonics. These signals are readily distinguished from ferrous alloys and noise.
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