Abstract: The basic theory of cable tension measurement and its examination technology by the method of vibration wave are introduced in this paper.In practical measurement, it has found that stress wave excited by the sinusoid impulsion contains too much noise, so the time difference between two signals could hardly be discerned.According to the theory that the maximum modular values of wavelet transform signals and random noises have different spreading characteristics, wavelet sym3 which has approximately symmetric character is adopted to decompose the noise signal, and each wavelet transform coefficient is conducted by different soft threshold.The noise-extracted signal which is reconstructed by the revised wavelet coefficient could clearly reflect the time difference between incidence wave and reflection wave.

Key words: soft threshold, wave-based method, wavelet transform, de-noise, cable-tension