Page 7 - EngineerIT December 2021

ICT

SANSA: Ten years of excellence in

HF Communication

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

EngineerIT | December 2021 | 5