Abstract: A timing system is disclosed for reading symbol sites, analog or digital from a video signal preferable in a recorded laser format. A video signal having analog data events at precise timed intervals is recorded on a first commercial grade video recorder. The tape is replayed through a second commercial grade recorder to an optical lathe. At the time of playback to the optical lathe, a timing signal is derived from a phase lock loop circuit added to the second commercial grade and recorded on the FM band of the video signal, which signal is then etched by the lathe onto a master optical disc. Simultaneously with the recordation of the substantially continuous FM band, selected horizontal scans on each frame are loaded with both timing and reference level data, the timing portion of these selected scans being later used for phase comparison of the signal. An optical disc master results which has a continuous FM band timing track as well as an interleaved timing information contained in the video signal.

Abstract: Data for recordation on a video disc is given multi-redundancy at block, field and group levels. Raw data is filled typically serially row by indexed row of 8-bit words with at least one and preferably 3 words being auxiliary check words derived from the remainder of the data field of the block. Block filling is completed with the addition of preferred Reed/Solomon error-correction redundancy filling two rows for column error detection and correction and two columns for row error detection and correction. Thirty blocks, so prepared, are processed to obtain two redundant blocks, completing a 32-block data field. Writing the data onto the video disc occurs with a three-dimensional diagonal interleave at the field level. After interleave each field is additionally XORd with 62 other fields to create a redundant field. This redundant field plus the 63 data fields comprise a group. The group of fields is written to the video disk so as to maximally spatially separate adjacent fields.