Analyzing digital overlay technique over marine voice channel for disaster dissemination

Regardless of much advancement in terrestrial communication technologies, marine communication technology has been stagnating for the last few decades especially with fishing vessels. Bringing a new communication technology in marine is difficult because it should consider maritime regulations and should be interoperable with the existing systems. Even though GPS assisted navigation aids have attempted to bridge this gap, they are restricted to large marine vessels and support high data rate transmission which is not required for alert messaging. There is an imperative need for a low data rate digital communication network for fishing vessels. This work analyzes various PHY layer characteristics for optimizing the performance of VHF maritime networks. This involves the selection and study of a suitable transceiver IC and analysis of modulation schemes supported by the IC using NI PXIe. Modulation blocks are implemented in Lab VIEW and the frequency spectrums are analyzed by varying the frequency range, resolution, and data rate according to our requirements. An on demand hopping algorithm is also devised and the effect of digital transmission over analog channels is also analyzed using NI-PXIe.