Method and system for broadcasting a digital data signal within an analog TV signal using Orthogonal Frequency Division Multiplexing

A method for transmitting digital data within an analog TV signal comprising the steps of:

• receiving the digital data from a data source;
• multilevel encoding the digital data and providing a plurality of data symbols in dependence thereupon;
• modulating in frequency domain each of the plurality of data symbols onto a carrier of a plurality of carriers such that each carrier carries a different data symbol using a serial to parallel converter for providing a digital data signal in dependence thereupon, wherein some carriers of the plurality of carriers are turned off in order to shape the spectrum of the digital data signal such that the spectrum of the digital data signal comprises notches at locations coinciding with locations of spectral components in the vestigial sideband of the video carrier of the analog TV signal, and wherein the width of the notches is determined such that degradation of the analog TV signal due to the transmission of the digital data within the analog TV signal is substantially reduced;
• transforming the digital data signal into time domain using IFFT;
• D/A converting the digital data signal;
• combining the digital data signal with the analog TV signal by inserting the digital data signal in the vestigial sideband of the video carrier;
• RF upconverting the combined digital data and analog TV signal to a broadcaster's RF frequency;
• and,
• transmitting the upconverted combined digital data and analog TV signal.

A system for transmitting digital data within an analog TV signal comprising:

• a port for receiving the digital data from a data source;
• a processor for encoding the digital data and providing data symbols, for modulating in frequency domain each of the data symbols onto a carrier of the plurality of carriers such that each carrier carries a different data symbol using a serial to parallel converter for providing a digital data signal, wherein some carriers of the plurality of carriers are turned off in order to shape the spectrum of the digital data signal such that the spectrum of the digital data signal comprises notches at locations of spectral components of the analog TV signal, and for transforming the digital data signal into time domain using IFFT;
• a D/A converter for converting the digital data signal;
• a combiner for combining the digital data signal with the analog TV signal;
• and,
• a RF upconverter for upconverting the combined signal to a broadcaster's RF frequency for transmission.