Theory and methods for design of pulse shapes for broadcast teletext

摘要

The theoretical and practical engineering constraints, considerations, and methods for pulse shape design for North American broadcast teletext transmissions are described. The principles and concepts described are for broadcast over-the-air transmission, but they are also applicable to satellite and cable transmission of broadcast teletext signals. Overall objectives of pulse shape design are summarized. Basic constraints and considerations from the Nyquist theory are described. The practical and engineering constraints on teletext pulse shapes are discussed in detail. Pulse shape apportioning and specification are treated. A critical review is provided of the theory and design methods for teletext pulse shaping. A review of analytical and numerical approaches is given. Modelling and simulation approaches are described, including novel comprehensive model. Improved overall and transmitted pulse shapes are evaluated and their performance compared to that obtained with other common pulse shapes.