Information signals are redundantly processed by an apparatus which utilizes two channels, each channel having at least one shift register. A first block of information signals is loaded into one shift register at one clock rate. It is then read out and re-loaded into the same shift register at a second higher clock rate. It is then read out a second time at the higher clock rate. A second block of information signals is similarly processed in the corresponding shift register in the other channel in an offset time interval with respect to the operation of the first shift register. The apparatus provides first and second representations of the information signals processed by the shift registers so that first and second representations of the first block of information signals followed by first and second representations of the second block of information signals may be, for example, recorded, in the order named, in a single track of a record medium. Thus, if an imperfection exists in the first block of data, data can be recovered from the second block.
The concept of the disclosed invention is to interleave a data bit stream with itself in such a way that the respective interleaved portions are displaced from each other, within the medium, by a distance corresponding to at least the statistical maximum size of the defects. In the event, during playback, that a dropout should occur, that dropout--inherently--must affect both interleaved portions. Therefore, by continuously delaying timewise one such interleaved playback portion relative to the other for a time sufficient to bring the two playback portions into sync with each other, the original bit stream may be reconstituted by toggling back and forth between the two playback portions each time a dropout is detected in either playback portion.
The present invention involves apparatus and techniques for converting analog data, preferably audio signals, to digital information, which digital information is preferably recorded from two separate main channels onto main tracks and includes a third or backup track for recording thereon partial or most significant portions of that information recorded on the main tracks. The invention involves apparatus and techniques of each data group on each main track and the backup track; checking for synchronization codes arranged between data groups; and checking for a match of that appropriate portion of the main track data against the data on the backup track, with, when potentially erroneous or questionable data is detected, the invention providing for comparison of main and backup track data groupings for determining which is most likely correct or, in the case where neither data grouping is identifiable as most likely correct, the invention provides for substitution of last correct data or integration between good data. The preferred invention incorporates clocking at the signal input for data stablization, and first-in-first-out circuitry at the output for reducing the effects of wow and flutter to produce a very high quality conversion of digital to analog form to pass to a speaker system.
A pulse code modulated audio signal transmission system which compensates for signal interference in the pulse code modulated audio signal. The system includes a first device for receiving an audio signal and for converting the audio signal into a pulse code modulated audio signal, and a second device for receiving the audio signal and for producing an auxiliary signal corresponding to the audio signal but having a smaller bandwidth than the audio signal. A transmission circuit is connected to the first and second devices for receiving the pulse code modulated audio signal and the auxiliary signal and for producing an output signal which comprises the audio signal with portions of the audio signal which contain interference being substituted with corresponding portions of the auxiliary signal.
An encoder circuit utilizes a pair of digital memories clocked at a slower write than read rate to compact analog input data, blanking and synchronization pulse intervals, and generate NTSC video. The NTSC formatted data may be stored utilizing conventional NTSC tape or disc recording equipment or may be transmitted, duplicated, monitored or transcribed utilizing readily available NTSC video equipment. A decoder circuit is provided to reprocess the NTSC video formatted data and restore it to its original form by removing the synchronization and blanking intervals and, utilizing a pair of digital memories clocked at a faster write than read rate, re-stretch the data which was compacted in the time dimension by the encoder circuit.
An information carrier having a surface upon which the information is stored. The surface having a first series of lineal regions and at least a second series of lineal regions with the second series being spaced from the first series of lineal regions. The first and second series of lineal regions are used to provide duplication of the stored information at two locations on the carrier so that even if a defect occurs in one region the information can still be read from another region. When stored on a disc, the different series of lineal regions can be arranged in a banded structure, whereby each series is separated from the next by a prescribed radial spacing. Alternatively the separate series of lineal regions can be arranged in interleaved fashion progressing radially on the disc. In either the banded or interleaved embodiments, the information contained in each series may be comprised of a plurality of progressing concentric circular segments or, alternatively, a plurality of substantially circular segments arranged along a spiral path on the disc.
