Comparison of new technologies for data exchange in the maritime HF frequency band

摘要

Recently, the use of HF radiotelex on ships, as the only terrestrial communication system for data exchange has been kept to a minimum, and the need for alternative systems, which would use the existing HF communication channels to exchange data between ships and end users on land, arose. Satellite communication systems represent the main aid for the exchange of large amounts of data with high transmission rates, but at high costs of equipment and services. Hence, there is the need to explore new, simpler and cheaper technologies for data exchange, which could be an alternative or a substitute for the existing radiotelex system. In this paper, a detailed analysis of the two systems, which could easily replace the existing maritime NBDP (Narrow-Band Direct Printing) telegraphy, has been done. One of the systems is based on the OFDM (Orthogonal Frequency Division Multiplex) protocol, while the other, on the PACTOR-III protocol. The systems were compared on the basis of the various relevant parameters, such as the modulation method, data rate, etc. The analysis results can be used in the selection of the optimal data exchange system with respect to the specific features of maritime communications.