Shipboard military and marine VHF and UHF communications: open sea communication range in the Adriatic Sea

This paper covers the specifications and performance of the common military and civilian marine radiocommunication systems. Covered military systems are NTDR (Near-Term Digital Radio) and SINCGARS (Single Channel Ground and Airborne Radio System), while civilian communications encompass marine VHF (Very High Frequency) radiotelephony and AIS (Automatic Identification System). The primary aim of this paper is to investigate the communication ranges of the aforementioned systems when used onboard a ship and put these ranges in the geographical context of open sea communication in the Adriatic Sea. Analyzing the calculated range using Friis equation yields that the limiting aspect of the successful VHF/UHF transmission is not the free-space link budget, but the radio horizon that is determined by the antenna height. We calculated the communication range for the expected ship-to-ship and ship-to-shore communication parameters for various cases and illustrated it on the map of the Adriatic Sea. The results indicated the importance of the strategically placed coastal repeaters and planned infrastructure of the radio network to ensure the success of the communication within the waters under Croatian jurisdiction.