Compatibility Problems in Add-On Data Transmission for TV-Channels

Transmitting additional data over TV- channels opens the way to several new services. In add-on data transmission a data signal is added directly to the video signal. No use is made of blanking intervals and no additional bandwidth is needed. The compatibility requirements for the video and the data reception are discussed. Considering an image as a function of three variables, data signals for correlation reception are described in the spectral domain of three-dimensional Walsh functions. The results are interpreted in the domain of the Fourier spectrum. A computer simulation demonstrates the feasibility of an add-on transmission system. Finally a block diagram of a correlation receiver for the specific three-dimensional data patterns is developed.