According to Digital TV Research, the number of homes receiving digital terrestrial TV (DTT) signals will more than double between 2013 and 2018, reaching 553 million. The research house forecasts the number of primary DTT homes (those not subscribing to cable, IPTV or satellite TV and using DTT on their main set) will also double over the same period, to 380 million in 2018.More than a third of the world's TV households are expected to receive DTT signals by 2018, up from 15% at end-2012. From that total, nearly a quarter are expected to be primary DTT homes by 2018, up from a tenth in 2012.