Making HF Useful 365 Days a Year, to Make Sure it Works the one day you Need it

High-Frequency radio (HF) is well known and well used in post-disaster communications. We estimate that there are several hundred HF radio installations in the South-West Pacific Islands alone. However, HF as ordinarily used has a major problem: It can only be used by the people who own and operate the system, and it requires trained operators. Where systems for automating HF radio exist, such as Barrett's 20-20 email-over-HF system, this in practice requires the use of specially configured computers, that are effectively tied to each HF location, so that messages can be correctly delivered. This has meant that mobile devices could not be used, and that casual citizen-to-citizen communications using mobile telephones has not been possible. In this paper we present preliminary results from the further integration of the Serval Mesh with HF radio, allowing exactly this use case: The use of ordinary Android phones, which are common in the region, allowing NGOs, government and the general public to make use of existing HF radio communications every day of the year, and without any special training, and without the need for the HF radios to be attended. Specifically, we present our refined Serval Mesh to HF radio interface, that automatically uses heuristics to determine the probable location of each subscriber in a multi-station and potentially multi-hop HF network, and automatically prioritizes and delivers messages over this backbone. From the end-user perspective, they simply continue to use their existing smart-phones and Serval Mesh Extender devices to send and receive both social media and private messaging content. From the perspective of the government or agency who deploys the HF radio, they are able to transform their asset from an emergency-only facility to a facility that is used orders of magnitude more, thus increasing RoI, but also helping to ensure that faults are discovered between disasters, rather than during them. For particularly remote locations, this also offers the potential to provide communications into and out of such locations on a cost-effective basis for the first time. This ability to provide affordable communications using infrastructure that is typically already installed has the potential to radically improve the resilience and socio-economic opportunities for people in remote communities. By working with mobile carriers to implement a Serval Mesh to SMS gateway, which has already been designed, it would be possible to provide global two-way communications into even the most remote locations on a much cheaper basis than installing cell towers, thus greatly expanding the area of communications coverage that can be provided on an economically sustainable basis.