Method and system of detecting signal presence from a video signal presented on a digital display device

A system comprising:

• an encoder to
• access a plurality of data bits, wherein some of the plurality of data bits are of a first data bit type and a remaining number of the plurality of data bits are of a second data bit type,
• designate a plurality of signal presences in a video signal, a particular signal presence of the plurality of signal presences being designated to raise luminance of a first consecutive frame and lower luminance of a second consecutive frame of a plurality of frames of the video signal in a substantially invisible way;
• designate a plurality of signal absences in the video signal, a particular signal absence of the plurality of signal absences is designated by passing through two consecutive unaltered frames of the video signal;
• and
• modulate the video signal based on the designating of the plurality of signal presences and the signal absences to produce a modulated video signal, the modulated video signal including the video signal modulated with the plurality of data bits,
• wherein raising of the luminance of the first consecutive frame increases total luminance of the first consecutive frame and lowering of the luminance of the second consecutive frame decreases the total luminance of the second consecutive frame.