Public Broadcasting Service

Superstorm Sandy, and similar disasters, have demonstrated the vulnerability of the nation's cellular telephone systems. Difficulties include overloads when usage suddenly increases; physical destruction of tower sites; and lack of sustained backup power. In contrast, US terrestrial broadcasters have a proven track-record to supply emergency information reliably, over large geographical areas and for as long as needed, as witnessed in the New York and New Jersey areas as well as in New Orleans (Katrina). Furthermore, digital television service to the home is now extended to mobile digital television (mobile DTV) serving portable and handheld devices including those in high speed vehicles. Mobile DTV is currently deployed in 50 major US cities by more than 140 stations with many more in the planning stages. Recently, the ATSC (Advanced Television Systems Committee) has also standardized the Mobile Emergency Alert System (M-EAS). M-EAS can provide both the familiar text "crawl" emergency alerts, and more complex and useful rich media information such as maps and video. M-EAS can be implemented in stand-alone devices, in cellular telephones, and/or in accessory hardware for existing devices.

This paper discusses the general approach of objective and subjective evaluations on digitally compressed video. After brief review of digital compression principles, artifacts associated with video compression are identified along with their origins. To investigate the usefulness of the conventional NTSC test signals and measurement procedures, both analysis and experiments were carried out. Observations are made based on the experiments. Also, some new objective test signals and measurement methods are presented and the application of these methods for assessment of compressed video is discussed. For subjective assessment, the design of testing is reviewed first. Issues which may affect success of subjective evaluation are discussed in detail. The importance of choosing critical test sequences is stressed and some guidelines on what kind of test material may be chosen are given. Finally, some new proposed methods and suggestions for performance evaluation are reviewed.

Will instructional television help solve some of the problems secondary schools will be facing in the 80s? That question was addressed during NASSP's convention earlier this year and is raised again here in several articles by many of the speakers wishing to demonstrate how ITV can help solve problems like student discipline, new curriculum needs, and the like.

In recent years the growing use of vertical interval data transmission systems in television broadcasting, such as the Captioning for the Deaf system1 developed by the Public Broadcasting Service (PBS)*, has created a renewed interest in the problems of multipath distortion.2 This interest is heightened by the fact that new devices, such as microcomputers and charge coupled delay devices (CCD's), make possible an economic solution to this problem for the first time, not only for data but for video as well3, although the work described herein has concentrated primarily on data applications.