HF Radio is an important naval communication channel for Beyond Line Of Sight (BLOS) communication. Although SATCOM is increasingly used for BLOS communication, HF is an important alternative for various reasons, including:

• Operation in SATCOM-denied environments
• As a back-up to SATCOM
• To support operational situations where it is desirable or essential to avoid use of SATCOM

BRASS (Broadcast and Ship to Shore) is used by Navies, particularly in NATO countries, to communicate between Ships and Shore using HF Radio.

The central part of BRASS is broadcast of messages from transmitters on shore to be received by all ships. This is a continuous stream of data, which will typically be transmitted over multiple HF frequencies at the same time, providing an uninterrupted data flow from ship to shore.

Using broadcast for shore to ship HF transmission is a sensible approach as many messages need to go to multiple ships and this approach takes natural advantage of the broadcast nature of HF transmission.

A key goal of BRASS is to give a high probability of message reception by ships which are in EMCON (Emission Control) and cannot transmit data.

Source : https://www.isode.com/