signal paths if the whole UHF band had to be covered. Even if digital TV is eradicated globally from the upper UHF bands then a single receive chain would still seem unlikely for a device capable of receiving DVB T and ATSC broadcast. The alternative is to manufacture devices that are regionally or nationally or band specific, but this frustrates scale economy and prevents products being used universally. The holy grail is to produce high-Q tracking filters that can be channel rather than band specific combined with active components that can maintain their efficiency over extended operational bandwidths, but these devices remain an ambition rather than a present reality, at least in present transceiver designs. But incremental progress is being made. The industry news flow tends to concentrate on baseband devices but in practice and as stated in earlier chapters the advances being made in new passive and active materials including RF MEMS, silicon on sapphire and BST-based devices are likely to be at least as important. The future of mobile TV will therefore be dependent on materials and manufacturing innovation. 15.21 And Finally the Issue of Potential Spectral Litigation Parts of this chapter have highlighted the coexistence issues implicit in the WRC 2007 deci- sions. In this final section we review the spectral litigation risks that are arising as terrestrial broadcast, cellular networks and white-space devices compete for UHF spectrum and why these risks may increase over time. An important objective of any regulatory process is to avoid or minimise the impact of spectral ownership disputes. An increase in the number of disputes and related costs implies a failure of the regulatory process. The US 700-MHz auction and its aftermath from 2007 to 2011 provides an example. The context is a block of spectrum called A block that a number of mobile broadband operators bid for when it became available postdigital switchover. A block is immediately adjacent to the top of the TV broadcast band. The bidding entities i