METHOD OF AND APPARATUS FOR CORRECTING AFFECTED DIGITAL CODED DATA RECORDED ON MAGNETIC TAPES

To correct erroneously recorded video data, or other data which have periodically recurring gaps or intervals in the data stream, the data are applied to two channels, one channel applying the data to a recording head (2) on the tape, and immediately thereafter reproduction by a reproducing head (4); the second channels applies the data to a time delay circuit (14) which has a delay time corresponding to the time interval between recording/reproduction in the first channel. The time-delayed original data in the second channel are compared with the reproduced data in the first channel by a correlator (13), and if the comparison indicates inconsistency, the time-delayed data are stored, for example in a random excess memory (RAM) 23, and re-recorded upon recall from the RAM 23 during a recording interval or gap, as determined by a control signal applied to a transfer switch (6) in series circuit with the recording head (2). Substantial deviation between the data in the first and second channel can also be indicated by integrating an output signal from the correlator (13) representative of errors, and providing an alarm output (27, 28) if a certain alarm threshold reference is exceeded.