Broadcast-Wave Relay Technology for Digital Terrestrial Television Broadcasting

Digital Terrestrial Broadcasting (DTB) services were started in three major Japanese urban areas-Tokyo, Osaka, and Nagoya-in December 2003. These services will eventually be made available throughout the entire country before the termination of analog television broadcasting services scheduled in 2011. A large number of relay broadcast stations are required to deliver DTB signals throughout the country, and reducing the cost of these facilities is a matter of considerable importance. Signals can be delivered to relay stations by dedicated lines such as studio-to-transmitter link/transmitter-to-transmitter link (STL/TTL) or by performing relay broadcasts. Relaying is especially important because it does not require new frequency resources and keeps the facility costs low. However, since a relay receives, amplifies, and retransmits the broadcast signals from the upper station, there are various factors that cause the quality of the propagated signal to deteriorate. At NHK Science and Technical Research Laboratories (STRL), we are researching and developing techniques that will alleviate these adverse effects. This paper presents an overview of these techniques and introduces the results of field trials of prototype equipment.