Compatible analog coding of television signals for correction of transmission burst errors: a computer evaluation

Methods for encoding a TV signal in analog or digital formats in such a manner that bursts of impulse errors can be corrected are described. The procedure is insensitive to ghosts and other horizontal processing, and can be applied to composite signals prior to operations such as ghost removal, separation of chrominance and luminance, motion estimation, and scan conversion; thereby, these latter algorithms and the image viewing quality are enhanced by burst error correction. Redundant lines, transmitted during vertical retrace, are added to each field in a TV signal. As few as two lines need be added, amounting to 0.76% redundancy, and they can be computed by the addition and subtraction of field lines, a special case of vertical (comb) filtering. The predicted performance in the presence of background and impulse noise is good, and is verified by computations on NTSC fields