Waveform generator for insertion of data into digital television signals

摘要

A digital waveform generator complies with different vertical blanking interval (VBI) standards, and is inserted into VBI portions of a digital component video signal. A buffer receives symbols carrying VBI data for a particular VBI service according to a user data syntax, which identifies a television line into which the VBI data is to be inserted. A symbol processor is responsive to information provided by the syntax. This information indicates the number of pixels represented per symbol, a symbol transition time, and the number of symbols carrying data to be inserted into the VBI portion. The symbol processor provides the VBI data in a format according to the particular VBI service. A timing circuit is responsive to a start time provided by the syntax for inserting the VBI data. A level control circuit adjusts the level of the VBI data prior to insertion into the VBI portion in response amplitude values provided by the syntax.