Performance enhancement of GMSK and LDPC based VLF communication in atmospheric radio noise

The performance of Gaussian minimum shift keying (GMSK) modulation scheme for very-low frequency (VLF) communication is evaluated experimentally in terms of the bit error rate. The atmospheric noise in this channel, which is predominantly non-Gaussian, is simulated using the clustering-Poisson model. A data-adaptive scheme is proposed for the suppression of the noise impulses for signal enhancement. The effects of channel coding and signal enhancement are presented, when the channel noise is modeled either as additive white Gaussian noise or as impulsive atmospheric radio noise. It is observed that the coding technique and the signal enhancement improve the performance of the communication system in the presence of the atmospheric radio noise, making it comparable with its performance in the presence of additive white Gaussian noise.