Abstract:

In order to improve the communication quality in extremely-low-frequency(ELF) communication, based on the generalized sidelobe cancellation(GSC) method, an improved GSC method is proposed and constructed. First, the delay summation in the main channel is replaced by the linear filtering algorithm, which is beneficial to further improving the suppression ability of incoherent noise. Second, by considering the difference in signal energy among channels, using the optimized blocking matrix can reduce the amplitude of the desired signal and improve the performance, comparing to the original blocking matrix obtained by simple subtraction among the main channels. Finally, the method using linear filtering instead of the original adaptive algorithm can achieve noise cancellation without reducing the sensitivity of the main antenna and improve the algorithm’s operating speed. In order to verify the effectiveness of the proposed algorithm, an experimental platform is set up in laboratory environment and a series of control experiments are designed. Experimental results show that the designed analog circuits can suppress 50 Hz and its harmonic components and that the improved GSC algorithm is better than the original algorithm in terms of improvement of the signal-to-noise ratio(SNR) and the noise floor.

Key words: extremely-low-frequency communication, noise reduction, analog circuits, magnetic sensors, generalized sidelobe cancellation, linear filtering