Modeling of Underwater Acoustic signal propagation of LFM and HFM pulse: An Active Sonar Communication systems

Sonar’s/Underwater Acoustic modems use various pulse types to characterize the target or to communicate with one another. However, in order to be able to use the sonar/Underwater Acoustic modem in any given sea environment the designer chooses a pulse waveform that suites the most. Underwater acoustic devises such as Active Sonars/Acoustic modems use different type of waveforms Pulse Continuous Wave (PCW), Linear Frequency Modulation (LFM) chirp signal, Hyperbolic Frequency Modulation (HFM) signals are to meet their underwater weapon designed requirements. The Active sonar system designer’s different environmental conditions while finalizing pulse type to be used in the sonar system for design goals. However, these pulse type waveforms perform differently under different sea environmental conditions. LFM signals are not easily effected by noise and most suitable for the sea environment that is characterized by multipath effect. When a source signal transmitting at arbitrary depth in shallow water and deep water then the influence on the acoustics signal processing is analysed. The acoustic signal propagation is different in shallow water and deep water due to variation of different factors such as Sound Speed Profile (SSP), depth of the ocean, range, Multipath effect and Doppler effect, the impulse response function of the channel was estimated using Bellhop-ray based model (ray theory) and VirTEX model the same was convolved with the source signal to predict the received signal. The results thus obtained will be plotted using MATLAB software.