Daniel G. Baker

Determining Valid Component Analog Video Signals with a 3-D Vector Representation

The traditional vectorscope display is limited in that it does not yield any information about color saturation because the vectorscope ignores the luminance content of colors. Since the color picture can be described by three parameters — hue, saturation, and brightness — the color picture takes on a 3-D nature and the 2-D vector display is incomplete. A new vector display has been proposed which allows the relationship between luminance and the color components to be displayed. This article demonstrates the utility of a 3-D spatial representation of component color signals. The combination of this new display and the traditional display provides a complete description of the color components as orthogonal 2-D vector projections of a 3-D color vector space.

Digital-to-Analog Conversion — Data and Filter Requirements

Ringing in the analog waveform caused by the filter response to the converted digital data is not a new problem. Early digital-based character generators for composite television applications caused significant ringing because the digital data produced too sharp an edge in the picture. Due to the specifications of component digital video, these edge effects are once again becoming more apparent in television operations. This paper discusses the results of using 13.5-MHz, luminance sampling to obtain flat analog bandwidth to 5.75 MHz, and how the filter template required by the international standard will inevitably result in some noticeable ringing on fast picture transitions. Data requirements in the digital domain are analyzed using 2-T pulses as an example while suggesting a different edge transition that will produce much less ringing. Designers are advised to consider the application of filters or edge processing to reduce the ringing due to digitally generated signals.

Monitoring and Control of Audio-to-Video Delay in Broadcast Systems

New digital processing capabilities over the last decade have resulted in higher expectations from television, including increased channel capacity and video and audio quality improvements. However, one of the first viewer determinates of television program quality has proven to be the proper and consistent synchronization of the visual and audio signal elements, otherwise referred to as lip-sync timing. This paper will provide a brief overview of the reasons for the increasing audio-to-video delay problems, discuss the thresholds for audio-to-video delay perceptibility that have been accepted in recent documented studies, and introduce a new in-service A/V delay measurement and auto-correction method based on digital watermarking of video signals.