Study on the characteristics of VLF atmospheric noise and its influence on the receiving performance

In this paper, the statistical characteristics of VLF atmospheric noise are analyzed, the mathematical expressions of amplitude probability distribution and pulse time distribution are derived, and the exponential normal narrow-band noise model of atmospheric noise is established. On this basis, the receiving performance of VLF communication system in atmospheric noise is simulated by MATLAB, and the influence of atmospheric noise on the receiving performance of the system is analyzed. The simulation results show that when the atmospheric noise intensity reaches a certain level, the rate of decline of the received bit error rate of the system will slow down or even not decline with the increase of the signal-to-noise ratio. Therefore, in order to ensure the reliable reception of the signal, the received signal must be processed in order to suppress the atmospheric noise and improve the reception performance.

I. Introduction

Very low frequency (VLF) radio waves propagate in the "earth-ionosphere waveguide", and the propagation is relatively stable. However, the noise in the frequency band is large, and the main noise source is atmospheric noise. VLF atmospheric noise is mainly caused by lightning instantaneous discharge in the world. Because the occurrence time of lightning discharge is random, and the noise intensity is related to frequency, geographical location, season and other factors, the analysis of atmospheric noise becomes more complex.