Digital migration in the Karoo – the benefits to MeerKAT and SKA
The recent move by South Africa to switch off analogue television in the Karoo, as an initial phase to a national digital migration, is a momentous achievement towards freeing up highly sought after radio spectrum as recommended by the International Telecommunication Union (ITU). Analogue television signals occupy a large frequency band from 470 to 854 MHz and this digital migration means that this band has been released for radio astronomy purposes and scientific activities in the Karoo.
Increased radio spectrum availability contributes to the accessibility of television, internet connectivity, cellular phone and radio astronomy services. In certain frequency bands, the demand for spectrum from different services far exceeds the amount of spectrum available. Spectrum management processes create a conducive environment for competing services to coexist, and regulations are necessary to ensure interference free operation for all stakeholders.
To preserve the astronomy advantage of the Karoo areas for the purpose of radio astronomy, the South African government elected to promulgate the Astronomy Geographic Advantage Act, 2007 (Act No. 21 of 2007) and associated regulations to protect radio astronomy facilities from sources of radio frequency interference (RFI) and Electromagnetic interference (EMI). Analogue television switch-off improves the astronomy advantage of the Karoo areas.
The figure above shows the area in the Karoo protected by the Astronomy Geographic Advantage Area Act.
The benefit that this digital migration holds for the communities include:
- They are provided with a broader range of good quality signals, allowing access to more television channels;
- The country will have additional spectrum to deploy broad band services such as voice telephony, internet, video applications, etc.;
- The components of the technologies employed to support the digital migration are manufactured locally and new assembly lines were established, thereby constituting the establishment of new business.
A number of government departments and agencies had to participate in order to make digital migration a reality. These include the Department of Communications, the Independent Communications Authority of South Africa (ICASA), SENTECH, Universal Service and Access Agency of South Africa (USAASA), South African Postal Office (SAPO), the South African Broadcasting Corporation (SABC), and many other broadcasting digital migration stakeholders. SENTECH, who is licensed to provide Electronic Communications Network Services (ECNS) and Electronic Communications Services (ECS), placed High Mast transmitters across the country and satellite transponders were acquired for television broadcasting in South Africa. In addition, with the manufacturing and assembly of suitable set top boxes (devices used in domestic dwellings to decode the digital signal), South Africa positions itself to manufacture digital televisions.
Analogue television had issues of inconsistency in the quality of the received signal. Some areas were able to receive good quality broadcasts and others would receive poor quality broadcasts. Different areas across the country had different numbers of broadcast channels from which to choose. The area around the SKA site was mostly limited to only one channel. The Digital Migration will now allow for a consistent service to be provided across the country.
The communities around the SKA site were given satellite television receiving equipment which eliminated the need to continuously adjust channels and surfing through frequencies to locate the optimal signal. These communities were the first to receive set top boxes and these were fully subsidised.
The Karoo area is now one of the few places on earth where radio astronomers can observe in the spectrum which was previously used for television broadcasts.