0 pixels. A high-end HDTV display is 1,920 pix- els wide by 1,080 active lines, resulting in 2,073,600 pixels-six times more pixels than the older NTSC resolution. DTV not only improves the visual experience, it also improves the sound qual- ity, using advances in digital sound. HDTV broadcasts sound by using the Dolby Digital/AC-3 audio encoding system, which is the same digital sound used in most movie theaters, in DVDs, and in many home theater systems. It can include up to 5.1 channels of sound: 3 in front (left, center, and right), 2 in back (left and right), and a subwoofer bass for a sound you can feel (the .1 channel). Sound on DTV is CD quality, with a range of frequencies lower and higher than most people can hear. DTV Implementations and Distribution Service providers increasingly interested in providing service bundles-a strategy often referred to as triple play (voice, data, and video) or quadruple play (voice, data, video, and wireless/mobile). Chapter 10 Next-Generation Networks DTV, which is a big part of this service strategy, can be implemented and distrib- uted in a number of ways. The following are some of the possible implementations: Terrestrial DTV-A number of countries are in the process of deploying digital terrestrial television (DTT), which offers many advantages. Govern- ments see DTT as an opportunity to free up existing TV frequencies for resale, as well as a technology that ensures that the country is on the fore- front of the digital revolution. Broadcasters see DTT as a means by which they can fight the growing competition from cable DTV, satellite providers, and telcos, not to mention emerging digital program distribution technolo- gies such as PVR/DVR and video-on-demand (VOD). Manufacturers see DTT as an opportunity to sell new equipment, ranging from digital set-top boxes to new DTV sets. Consumers view the move to DTT as a way to get new and exciting programming. At the moment, however, HDTV sets are still very expensive, and there is not much HDTV programming available. Sate