Digital information storage and retrieval using video signals

A video disc for storing digital information by imprinting said information thereon with video frame signals created in accordance with the steps of:

• delineating information frames in said digital information by selecting sequences of a preselected number of multi-bit words;
• appending to each of said information frames a sync sequence and cross-interleaved error correction codes related to said preselected number of multi-bit words of a fixed number of said information frames to develop information frame sequences;
• separating each of said information frame sequences into multi-bit information samples equal in number to the number of samples selected for said video frame signals and converting each of said multi-bit information samples into an analog level, to develop an analog frame signal for each of said information frames;
• and
• adding video characterization signals to said analog frame signals to develop said video frame signals.

A video disc having digital information stored in the arrangement of pits and lands along a track, where the length of said pits and lands is related to the zero crossing of a signal which, when frequency demodulated, is characterized by:

• a plurality of concatenated video signal lines for storing a predetermined number of bits of said digital information and each beginning with a horizontal sync pulse and followed by a second plurality of analog samples;
• where each of said analog samples within each of said video signal lines represents a derivable multi-bit sequence, and the concatenation of said each derivable multi-bit sequence with derivable multi-bit sequences of adjacent analog samples within each of said video signal lines forms a frame sequence;
• and
• where said frame sequence comprises a first and second set of error correction codes and a plurality of message words, with said message words being related to said predetermined number of bits, said first set of error correction codes being related to said predetermined number of bits, and said second set of error correction codes being related to a rearrangement of said predetermined number of bits of a number of said video signal lines.

A method for storing digital information in video lines characterized by horizontal sync pulses and an analog video signal between said sync pulses that contains a predetermined number, I, of sample windows, comprising the steps of:

• selecting frames of NM bits of said digital information, with said NM bits treated as N M-bit input words;
• developing a first set of K1 error correction codes, each having L1 bits, from the sequence of said N input words and developing a second set of K2 error correction codes, each having L2 bits, from a sequence of said N input words derived from a rearrangement of input words of a set plurality of adjacent frames;
• combining said N input words and said K1 and K2 error correction codes with a frame synchronization sequence of L3 bits to develop a sequence of J bits, where J=NM+K1L1+K2L2+L3, and where M, N, K1, L1, K2, L2, and L3 are integers selected to satisfy the equation J=P1, P being an integer;
• and
• converting adjacent P-bit subsequences of said sequence of said J bits into concatenated pulse amplitude modulated analog samples to develop said analog video signal.

A system for retrieving digital information from a video signal characterized by frames of analog samples delineated by horizontal sync pulses, comprising:

• retrieval means for deriving said frames of analog samples from said video signal;
• threshold means responsive to said retrieval means for converting voltage ranges of said analog samples to multi-bit words;
• detection means responsive to said threshold means for discerning a synchronization sequence from among said multi-bit words;
• and
• decoder means responsive to said detection means and to said threshold means for extracting said digital information from said multi-bit words through a process that is the inverse of an encoding process that, for each segment of said digital information, develops a first set of error correction codes for said segment of digital information, rearranges the digital information of a fixed plurality of said segments, develops a second set of error correction codes based on digital information found in each segment following the rearrangement, and combines said first set of error correction and said second set of error correction codes with said digital information of said segment.

A system for retrieving digital information from a video signal characterized by frames of analog samples delineated by horizontal sync pulses, comprising:

• retrieval means for deriving said frames of analog samples from said video signal;
• threshold means responsive to said retrieval means for converting voltage ranges of said analog samples to multi-bit words;
• detection means responsive to said threshold means for discerning a synchronization sequence from among said multi-bit words;
• and
• switch means having one input and more than one output, responsive to said detection means and to said threshold means, for directing said multi-bit words of said threshold means to alternate outputs of said switch means under control of said detection means;
• and
• a cross-interleaved Reed-Solomon decoder connected to each of said switch means outputs.