Many sectors across the continent rely greatly on HF communications for aviation, disaster management, defence and security, sectorial disasters when all other forms of communications are off-line due to infrastructure damage or cellphone systems falling over due to traffic overload.
An example of this was during the Mozambique hurricane disaster, when cell phone systems became overloaded and satellite phones did not operate due to heavy cloud cover. This left HF radio as the only option for disaster relief communications. In fact, HF radio communications is an integral part of the community based disaster preparedness strategy for natural disasters in Southern Africa. At a recent African Telecommunication Union meeting in Maputo countries were urged to relook at their communications facilities to support disaster response teams and to allow cross border teams to provide communication if local systems fail.
HF communication can be independent from fixed infrastructure. In many instances it is installed in response vehicles. It can also be quickly set up in remote areas with simple antennas strung up between trees or any other buildings or structures. While a reasonable distance can be covered by the groundwave, for longer distances HF communication it is dependent on bouncing signals off the ionosphere. Frequency selection is an important criteria and countries are urged to ease license restrictions as much as possible and to assign frequency for disaster communication. The frequency which will provide reliable communication will vary during different times of the day and the distance to be covered.
However HF communication can be affected by adverse space weather events. The main driver of space weather is the sun and when solar flares and coronal mass ejections interact with the earth’s atmosphere, HF can be impacted and in severe cases cause complete radio blackouts.
For HF communications to provide a reliable link an operator needs to select the right frequency band for the path required.
Over the past decade the South African National Space Agency in Hermanus has become, a centre of excellence in HF Communication. SANSA has both the infrastructure and expertise to monitor the layers of the ionosphere that are responsible for HF communications, as well as to forecast the impact that adverse space weather will have.
SANSA Infrastructure includes a network of four Ionospheric Radars in South Africa. This is an instrument that continually measures the upper atmosphere to give an indication of what is happening at a particular time and place. It is considered the Rolls Royce of instruments for measuring the path that radio waves will follow through the ionosphere. The data from these instruments is sent to the SANSA Space Weather Centre in real time and forecasters use the real time data with additional data from the sun to predict the impact of Space weather on communications including HF.
In addition to infrastructure SANSA also has experts to disseminate and interpret information. These experts use the data from our instruments not only for real-time monitoring, but also to build models that predict the conditions for HF communications.
SANSA provides space weather information reports that are tailored to HF Communication and communications planning support based on user requirements.
SANSA has developed new software called Ionospheric Characterisation and Prediction Tool (IOCAP). This is a modern, user-friendly tool that is designed to simplify HF communications planning.
IOCAP features a robust, proven prediction engine that provides dependable frequency predictions in the 3–30 MHz frequency band. The application is simple to use and contains innovative features not found in any other HF prediction software. In addition, SANSA provides HF propagation training to users to enable a deeper understanding and appreciation for the science of HF communications and the impact from space weather events.
The combination of access to infrastructure, reliable data products, and experienced experts makes SANSA your go to organisation for any HF Communications requirements. A true centre of excellence on the African continent.
SANSA intends to continue research and development of HF Communications tools and services to assist the continent in ensuring the continued use of this reliable and cost-effective form of communications.