Performance evaluation of acoustic signals for underwater applications in high-frequency range

Performance evaluation of high frequency (20-24 kHz) underwater acoustic waveforms such as CW, LFM and HFM was carried out theoretically in the presence of white Gaussian noise, multipath and Doppler. Measured sound speed profiles off Indian coast were used in ray based models Bellhop and VirTEX to mimic the environment with multipath and Doppler. The source signals were convolved with channel impulse response function to predict the received signal. Correlation between the transmitted and received signal was used to evaluate the performance of waveforms. Performance evaluation studies have revealed that LFM and HFM have better resistance to additive white Gaussian noise than CW. Similarly multipath has affected CW the most while HFM and LFM are resistant to it. The Doppler imposed by the source/receiver motion has very little effect on HFM followed by LFM and CW. It was also found that both LFM and HFM have shown greater resistance to Doppler when the receiver is close to the surface.