Abstract:

The ship爷s shaft-rate(SR) electric field propagating in seawater at extremely low frequency, plays an important role in the non-acoustic detection. The different characteristic of wavelet modulus max- imum along with the scale is analyzed in the lab. Then the de-noising algorithm based on wavelet modulus maximum is introduced in the signal processing. With the Hermite interpolation being applied in the sig- nal reconstructing process from wavelet transform maxima, the practicability of this algorithm is ensured consequently. Finally, the mean energy at characteristic frequency is selected as characteristic value to detect the target by sliding power spectrum algorithm. The effectiveness of the detection algorithm is veri- fied both using measured data and simulated data. The verified result shows that the detection algorithm provides a better detecting performance and lower false alarm probability compared with the algorithm based on wavelet packet entropy. The detecting probability of this algorithm enhances about 50% when the signal-to-noise ration(SNR) is -5. 9 dB, and it can keep 86% when the SNR is -8. 2 dB.

Key words: information processing, ship, electric field, shaft-rate, wavelet transform, signal detection, algorithm