The data files are processed, encrypted and then transmitted to the user, where they are decrypted by the receiver. Other formats can provide some ‘infotainment’ such as audio broadcasting of live sports and/or ‘homeland-security’ broadcasts, intranet and WiFi. These include the provision of nautical data such as electronic charts, Gridded Binary (GRIB) weather data, Differential GPS information, NAVTEX/ NAVDAT and SAFTEY-Net MSI transmissions. With this technology, a variety of maritime applications can be delivered. The transmission capabilities of this form of digital point-to-multipoint broadcasting can provide data services to single ships as well as to larger naval units worldwide. I recently discussed with our editor, Georg Wiessala, a relatively new source of weather data the Digital Radio Mondiale (DRM) datacasting service provided by the company RFmondial. These are still transmitted via HF radio, along with RTTY weather data reports also transmitted by DWD on HF frequencies (see later in this column). There are many other direct transmissions of weather data such as the Radio Facsimile (Fax, WEFAX) charts produced by Deutscher Wetterdienst (DWD, the German Weather Service). Moreover, seafarers can get MSI data delivered by satellite communications and even download weather information from the internet. The relevant maritime meteorological data are also disseminated by means of Coastguard voice transmissions, in the shape of the Maritime Safety Information (MSI) broadcasts.
Furthermore, there are many NAVTEX and HF Narrow Band Direct Printing (NBDP) transmissions containing weather updates. In the British Isles, this includes, of course, BBC Radio Four’s Shipping Forecast on long wave ( 198kHz). According to these rules, weather information is delivered in different formats, including by means of broadcast radio. The Safety of Life at Sea (SOLAS) regulations of the International Maritime Organisation (IMO) entered into force in 1980. There is one piece of important information all vessels at sea require, be they large cruise ships carrying three thousand or more passengers, a super-tanker, a trawler or even a small day boat – all of them need up-to-date and reliable, weather information. Robert Connolly explains DRM weather ‘datacasting’ to ships, revisits the RTTY transmission mode and looks at synoptic weather forecasts, before diving into the fascinating history of the Shipping Forecast.
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