Strictly speaking what you are about to read is not focused upon HDTV. Most of the communications systems forming around the world, however, are major benefactors from the technical development of HDTV. As with NASA's spin offs the strengths found in HDTV solutions are becoming cornerstones for other services. In this article by DTV pioneer and designer Ed Milbourn we see such developments supporting the enjoyment factor of still another of our national pass times--motoring about the countryside. The kid in us is going to love this marriage between car and cartoon. _Dale Cripps

It's not HDTV - yet. But this application of digital television is truly a seminal event in expanding the amazing benefits of DTV technology. To punctuate that thought is the recent announcement by Sirius Satellite Radio that it will start providing MDT service in addition to its radio and data content, placing this company squarely in the Multimedia business. However, that's far from the whole story of this Sirius pioneering MDT effort. In 2003, Sirius had a vision that it could successfully expand its digital offerings far beyond audio to include truly mobile television with a very high Quality of Service (QOS). There are, of course, other wireless television services, including traditional broadcast, cell phone VOD, Wi-Fi/Max, DBS et al. However, most of these applications do not work well in high-speed moving vehicle applications. Small signal dropouts that are acceptable with broadcast audio applications are very annoying with video. Sirius successfully demonstrated satellite mobile television at the 2004 CES, but it lacked one major component - a partner with equal vision to make delivery of the service to the customer a viable commercial reality. Chrysler had that vision. Chrysler realized the most important customers for MDT are not the drivers, nor the front seat passengers, but kids in the backseat. With an increasing number of automobile purchase decisions being made by women (approximately 45% - up from 25% just 15 years ago) and with those decision focusing on family travel, safety and convenience, accommodation the kids becomes a major selling point. Further, today's family structure is increasingly mobile with both parents working, a greater variety of children's activities, and widely separated family members (not to mention the worsening hassle or air travel) driving the desire and demand for high-quality, in-car multi-media entertainment. In response, Chrysler and Sirius will start augmenting this demand by offering MDT in selected 2008 model year Chrysler Town and Country and Dodge Grand Caravan minivans, followed by the Chrysler 300, Dodge Charger, Dodge Magnum, Jeep Commander and Jeep Grand Cherokee. The MDT hardware price premium will be $470 above a required Chrysler entertainment center that includes dual DVD players and a front seat screen (not to mention several cup holders). The Sirius MDT service will cost $7/month when bundled with the standard $12.95 Sirius Service. However, the first year of service will be free. Of particular interest is the MDT service content itself. Tightly focused on those very discriminating, hard-to-satisfy back-seat consumers, the content will include purposely products offerings from Nickelodeon, Disney Channel and Cartoon Network. More channels are technically possible, however, the economic model build around these three popular children's programming services plus the standard Sirius audio service allowed meeting a marketing critical $19.95/month price point. Although conceptually demonstrated over four years ago, the final technical design and packaging tasks were not a small challenge. This required a very close design and product development cooperative effort between Sirius and Chrysler. The first task was to find the bandwidth for the video channels within the 12.5MHz already devoted to over 130 channels of audio and commercial data content - without compromising, but, indeed, enhancing the existing QOS. The answer to this salient problem was to employ a unique, proprietary "overlay modulation" scheme for the video data. Without belaboring the technical details and taking some liberal license in the explanation: the video data modulation scheme works by slightly offsetting the angular position of normal data symbols. This symbol "phasing offset" method creates additional positions for symbol energy that can be used to carry video and other data streams while remaining fully back-compatible with standard receivers. To maximize the video QOS, the receiving system employs a highly sophisticated time and spatial dual diversity antenna system. The result is not only enhances audio reception reliability, but also, most importantly, a video QOS of over 99% - with the vehicle in motion! The video compression system used in this initial application is a proprietarily modified version of the MPEG 4 based H.264 codec. This codec allows a high quality NTSC 320x240 line 15 or 30fps color video display with stereo sound, all at a per-channel (un-coded) bit rate estimated at approximately 200Kb/s for animated content. The kids will love it. After all, they run the show and call the shots. Ed