| 摘要 |
A method of detecting a coded magnetic thread is provided that includes sensing the response of a magnetic field detector as a thread passes the detector, the response varying from an initial magnitude in first and second senses to exhibit a first peak, and then in the first sense to exhibit a second peak; comparing the response with first and second thresholds disposed about the initial magnitude in the first and second senses respectively; and indicating the passage of a code element of the thread when the response passes the second threshold and then the first threshold in a predetermined manner characterized in that the first threshold is adjusted in accordance with a first predetermined algorithm based on the magnitude of the first peak. The first predetermined algorithm adjusts the first threshold so that the magnitude of the first threshold is the average of a predetermined number of preceding first peaks.
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