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Shipbone MF/HF radio equipment is required to install to the SOLAS convention ships that engage international voyage, and is even now the only shipbone radio equipment capable of long distance terrestrial communication. For a long period since the early twentieth century, the radiotelegraph communication with Morse code and the later SSB radiotelephone communication were the mainstay of the long distance communication for the ships. However, the distress signal of Morse code SOS had repealed because the Inmarsat communication system have spread and GMDSS have started. Instead the distress signal SOS, the function of distress alart by DSC (Digital Selective Call) have installed in MF/HF radio equipment as GMDSS. This report introduces technical evolution of JRC MF/HF Radio Equipment since approximately the start of GMDSS.

Eiichi Kobayashi
Shoichi Kuromori