According to Telemedia’s Andy Louis, the various improvements in satellite transmission technology over the past few years fit into one of the following two broad categories:
- improvements made in the coding (video compression) methods
- new frequency bands available for satellite transmissions.
Video compression
MPEG-4 video compression technology is now being widely used, almost exclusively for high quality, low bandwidth HD contribution links into the broadcasters, Louis explains. The next-generation compression HEVC (High Efficiency Video Coding) is available in the market, but has not as yet been adopted. DVB-S2, the second-generation modulation system, is also used extensively. DVB-S2X (Extensions) is now available, but is not widely used yet in South Africa.
These new technological developments require not only the transmitting station to upgrade, but also the single (or multiple) receive stations to be capable of receiving the signals.
New frequency bands
As far as transmission frequencies go, Louis says that, in recent years most of the major satellite manufacturers have been implementing K-Band beams as their next-generation platforms. Transmission frequencies are approximately 30GHz, and reception is either in the Ku-Band (10 to 12 GHz) or Ka-Band range of 20GHz. The main reason for the increase in frequency band is the simple fact that all other bands are already fully utilised. Ka-Band allows for a much smaller transmit antenna, but a much larger receive antenna, due to the huge atmospheric losses (rain fade) as a result of the higher receive frequencies. Satellite links operating in the Middle East and Europe rarely experience heavy rain. Ka-Band transmissions would work well in these areas, but not in the Equatorial regions.
Satellite broadcast across Africa has largely made use of C-Band beams, which perform far better in adverse weather conditions, preventing rain fade to a large extent. In the past year, there was a debate over whether to reallocate telecommunication services to the C-Band which, broadcasters argued, would seriously disrupt their operations, forcing them to move to K-Band transmission, resulting in less reliable service and thus a loss of revenue. The most recent iTU World Radio Conference (WRC) was held in Geneva in December 2015 and ended with delegates agreeing not to make any major changes to the C-Band allocations.
While K-Band frequency transmission and HEVC compression are the next step in the technological advancement of satellite broadcast, neither of these are likely to have a major presence across Africa anytime soon. Although the decision taken at the latest WRC means that broadcasters are, for now, not going to have to deal with the crisis that would certainly result from C-Band reallocation, the respite is likely only a temporary one. The issue is sure to come up again, with telecoms still eyeing these frequencies. With telecoms entering the content distribution space via a range of VOD platforms set to give traditional, linear, satellite and terrestrial television broadcast a run for its money, it remains to be seen how the balance of power will shift in this arena.
