The SABC and broadcast technology partner Siemens have achieved a world first by successfully conducting the first live radio transmission using a WiMax IP contributed feed.
A pilot project was run during the Vodacom Challenge football match between Manchester City and Kaizer Chiefs at the Absa Stadium in Durban. The objective was to establish the viability of transmitting audio feeds directly from the venue to the broadcast centre.
Johannes von Weyssenhoff, Siemens’ programme portfolio manager for radio, says the SABC had decided to upgrade the equipment in its radio broadcast vehicles from analogue to digital.
“At present, a broadcast crew runs large, heavy, copper analogue cables from the stadium to the vehicle positioned outside. This enables the commentator, who sits inside the venue, to transmit back to the SABC for broadcasting.”
Although the SABC has considered fibre cable, which is lighter and easier to install than the analogue cables, Siemens recommended using wireless technology.
“We identified WiMax technology as robust and fast,” von Weyssenhoff says. “It works in a similar fashion to a wireless Local Area Network (LAN), but is capable of extending over far greater distances.”
Siemens recommended direct line of sight for the pilot project at the Absa Stadium. Despite the newly-built Moses Mabhida Stadium, which is situated between the ABSA Stadium and the SABC Broadcast Centre, the signal was strong enough to penetrate the new stadium and give sufficient signal strength results over a three kilometre distance. Further obstacles included a wide range of interferences, mainly caused by the harbour location and associated sea traffic.
The link was established at the public frequency of 5.475GHz and 5MHz channel bandwidth, and a licensed spectrum would yield even better results.
“A data rate of 256kbps was used for the audio link – compared to the 64kbps offered by ISDN lines – and this provided a high-quality audio performance that was clearly noticeable when monitored off-air,” von Weyssenhoff says. “The link was bi-directional, so the commentator could receive their audio signal from the studio via the link as well. Two separate audio feeds were transmitted from the stadium to the studio: the commentary and the effects channel.”
Besides the enhanced audio quality, the WiMax link eliminates the use of cables, improves security and save costs. For example, a sporting event in South Africa typically involves 11 radio stations, each using an ISDN line to provide commentary to its target market. By using a WiMax link, all 11 stations would be able to transmit to the SABC at no additional cost – a huge saving.
The equipment was not installed permanently as the project was run on a trial basis. The SABC/Siemens team will conduct further investigations into the technology and run more trials. However, if the success demonstrated at the Absa Stadium continues, the intention is to make the installation permanent.
As the SABC’s broadcast technology partner, Siemens initiated and drove the trial, which included identifying appropriate industry partners such as B&I Engineering, which provided and set up the audio equipment, and Multisource Telecoms, which provided and set up the WiMax equipment. The equipment used included the MicroMaxd ProST WiMax standalone base station from Airspan in the US, and the TLF 300 commentator mixer from Tieline Technology in Australia.
“Now that this technology has been proven so successfully, we have initiated further trials and will be involving ICASA in our preparations. During the current phase of trials we will test different frequencies, venues and events such as concerts,” von Weyssenhoff says.