Trialing the future of broadcast
At RFS it’s always been a pleasure to be involved with an array of exciting projects, from the One World Trade Centre deployment, to supporting state driven education projects in Arkansas. However, one of the most exciting and challenging projects we are currently working on is the SBTVD forum trials taking place in Brazil. The project is looking to test and compare future standards combined with both MIMO and channel bonding technologies for over the air broadcast transmission. The aim of the trial is to provide real world results that will enable informed discussion and decisions and the results could have a huge impact on what that future of broadcast looks like.
The trials are comparing different types of orthogonal polarization MIMO transmission across four different broadcast standards. They are the Chinese standard — DTMBA, the Japanese standard — ISDBT advanced, the US standard — ATSC 3.0, and 5G broadcast. The trial organizers were looking for equipment that would allow the candidate solutions to be tested in the most controlled conditions possible. This meant limiting the number of variables to ensure that the experimental results were not impacted by additional factors, for example equipment that would need to be mounted at different heights for each experiment. The RFS solution therefore needed to be flexible enough to allow all the different MIMO configurations to all be transmitted from a single antenna at a fixed height on the tower.
This is exactly what we were able to deliver. The system we offered can transmit three different combinations of orthogonal polarizations, be that horizontal and vertical polarizations, +/- 45-degree slant polarizations, or dual left-handed/right-handed circular polarizations. The changes can be made by a simple adjustment at the transmitter which allows for the most accurate and controlled testing possible because the transmission emanates from exactly the same location on the tower for each test. In addition to the multiple MIMO configurations, the system included filtering equipment to allow channel bonding of two broadcast channels. Moreover, this filtering system had to ensure that the two test channels used in this experimental SFN did not interfere with existing adjacent channel broadcast transmissions emanating from the main transmission site. Custom mask filter responses were developed that addressed the adjacent channel interference concerns.