| 摘要 |
PURPOSE:To improve a detection capability by simultaneously executing feature extraction of induction waveforms contained in plural magnetic field signals by respective adaptive and differential filters, executing smoothing suited to the respective characteristics and executing simultaneous comparing of the square values and variances of the differentiated signals. CONSTITUTION:In a fisrt level adjuster 11 and a second level adjuster 12, respec tive coefficients are found on the basis of the altitudes to adjust the amplitude of the magnetic fields. Then, at a moving average point calculating part 13, moving average point adjustment coefficients are found using the coefficients found at the adjusters 11, 12 and the altitude. At a second pulse generator part 14, periodic pulses are generated on the basis of the coefficients found at the calculating part 13. At first to third data buffers 15 to 17, magnetic field and synchronous pulses are inputted and updated pulses are outputted. At first-third adaptive filters 18 to 20, first-third smoothed values, indices and variances are outputted. At first-third differential filters 21 to 23, fisrt-third differential signal values are calculated based on outputs from the filters 18-20. In a discriminating unit 24, the inputted signals are discriminated to output discrimination signals.
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