| 摘要 |
A burglarproof system improving a tagged article detecting accuracy. A signal of a predetermined amplitude obtained by sine-wave sweeping a range of 7.4 MHz-8.9 MHz by 140 Hz is sent out from a transmitting antenna (1). At a signal reception side, a signal analysis unit (9) is provided which is adapted to predict the time of generation of a signal, which is to be received in the second half cycle in one cycle of the sweeping, on the basis of the time of generation of the signal received in the first half cycle in the same one cycle, compare the predicted time with the reception signal, and recognize the passage of an article when the predicted time and reception signal have reverse-phase relation with each other.
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