Talk outline.

1 Background

-　The significance of TV

-　The US change-over from analogue to digital TV

2 Overview of digital TV

-　How it is delivered to the viewer

-　How it is received by the viewer -　digital TVs and set-top boxes

-　Interactivity & interactive services

3 Accessibility issues

-　Closed captioning

-　Video description

-　STBs

-　Remote controls

-　Interactivity