The work of the detector consists of a transmitting gate, a receiving gate (single channel) or a transmitting gate and two receiving gates (dual channels). The basic principle is that the transmitting antenna emits a scanning band, and a scanning area is formed between the transmitting antenna and the receiving antenna, where an effective magnetic stripe appears. The receiving antenna receives the signal and triggers the detector host to alarm. I have worked in a library, and the detector can't tell whether it is a book in our library. If your new book is not degaussed, it will also ring. At this time, you can ask the library teacher, who will help you solve it.