Interference Signal Envelope Extraction Based on Wavelet Transform Method

In order to realize the measurement of coherence function of wide spectrum light source, the envelope of interference signal of the broad spectrum light source must be extracted. Thus the envelope extraction becomes the key factor for the measurement of coherence function. In consideration of the disadvantage of envelope demodulation, the interference signal envelope extraction was established based on wavelet transform method. It adopts the complex Morlet wavelet as mother wavelet which can extract the interference signal envelope effectively and has a good ability to resist noise by choosing a suitable scale parameter. Using the Matlab computer simulation prove the effectiveness of this method. Finally, the output signal's envelope of Fiberpro company's white light interferometer was extracted with this method and the dynamic range can reach -60 dB.