Error correcting apparatus

Abstract

A multiple track tape recording system as disclosed in which the data recorded in each track is coded to allow for error correction and skew correction. The skew correction is done with a code which also can be used for error correction. Thus the system overhead required for skew and error correction is reduced. The data in each tape track is first divided into data blocks of equal length. An error-correcting parity word is computed from the data bits in the data block and appended to each data block to form a code word. During the decoding operation, each tape track is fed through a first-in, first-out buffer memory (FIFO) and examined for valid code words. When a code word is detected the output of the FIFO for that track is stopped. After code words have been detected on all tracks the FIFO's are started in synchronisms, thus correcting for skew and synchronization errors. The code also allows for detection of both random and burst errors on each of the multiple recorded tracks. An additional error correcting decoder utilizing an additional recorded track is used to correct the detected errors.