Research on Power-line Interference Removal Method of Ultraviolet Communication Signal Based on Wavelet Transform

In the wireless ultraviolet communication system, fluorescent lamp can cause power-line interference to the system. The interference can be superimposed on the useful signal received by the photomultiplier tube in the form of a sine wave, which have a bad influence on the subsequent sampling decision stage. Firstly, this article analyzes the principle of wavelet transform to remove power-line interference noise, and gives a method to calculate the signal-to-noise ratio based on the received signal waveform. Secondly, the performance of wavelet transform to eliminate power-line interference is analyzed based on this signal-to-noise ratio calculation method. Finally, the problem of selecting the optimal wavelet basis in the process of the wavelet transform to remove power-line interference is discussed. The spectrum analysis shows that wavelet transform can effectively eliminate power-line interference of 100 Hz and 200 Hz, when the wavelet basis is sym40, the best performance in removing power-line interference is achieved, and the signal-to-noise ratio is 12.22 dB after denoising.