ATSC 3.0 Adjacent Channel Testing

The process of combining broadcast television channels on adjacent channels has always been a source of performance tradeoffs.  More than anything, this was due to the US ATSC 1.0 standard use of single carrier 8VSB, and its attendant sensitivity to signal distortion from roll off and group delay. Since the US spectrum repack, the chances of adjacent channels being occupied in a market is much more likely.  With ATSC 3.0 SFNs on the horizon, the reasons to need to implement adjacent channel combining will become even more common.  Adjacent channel combining is quite common in other parts of the world where OFDM modulation is used. This paper presents considerations made for designing an adjacent channel combining system and presents the results of testing to see what impact adjacent channel combining has on ATSC 3.0 modulation and coding selections.  That selection is important given that those two factors play directly into the robustness and receivability of ATSC 3.0 broadcast for specific applications.