Motion detection between even and odd fields within 2:1 interlaced television standard

A pattern interruption detector for controlling operation of a motion sequence pattern detector for detecting a periodic pattern of motion sequences within a video temporal signal stream from a source and including a frame motion detector means for detecting the presence of motion by comparing spatial picture data to similarly located, frame delayed successive spatial picture data within the video temporal signal and for putting out a frame motion detection signal for each comparison of said data and first logic circuit means responsive to a sequence of frame motion detection signals for detecting said periodic pattern of motion sequences within a video temporal signal stream and for putting out a pattern detection control signal, the pattern interruption detector comprising:

• input means for receiving the temporal video signal stream from the source,
• first delay means for delaying the video signal at the input by one field period less one half of one scanning line period and for providing a first delayed output,
• second delay means for delaying the video signal at the input by one field period plus one half of one scanning line period and for providing a second delayed output,
• first subtraction means for subtracting the first delayed output from the video signal to provide a first difference,
• second subtraction means for subtracting the second delayed output from the video signal to provide a second difference,
• first comparison circuit means for comparing the first difference with the second difference and for putting out a selected one thereof having a lesser absolute magnitude as a field motion detection signal,
• second logic circuit means connected to said frame motion detector means, to said first comparison circuit means and to said first logic means for detecting an interruption in the periodic pattern and for thereupon generating an inhibition control signal for inhibiting said first logic circuit means.