A NEW 8-12 CONVERSION CHANNEL CODE AND ITS APPLICATION TO HIGH DATA-RATE VIDEO RECORDING

Short wavelength recording requires a channel code that has a larger m inimum magnetic-transition interval (T-min) than the data-bit interval (T-b). An 8-12 conversion channel code has been developed in which T- min is 1.33 times longer than T-b. In this code, a maximum of four com binations of 12-bit channel codes are set for each 8-bit dataword. The proper channel code is selected by referring to the previous channel code and the tentative next channel code. A word-inversion scheme can be applied to this conversion channel code, drastically reducing the d e component of the code when the code is used in video-signal recordin g. As a result, when recording video signals, the de component and dig ital sum variation (DSV) characteristics of the new code are superior to those of the (1, 7)RLL code and similar to those of the NRZ-ASE cod e. Simulation showed that the 8-12 conversion code has superior eye-pa ttern and error-rate characteristics compared to the(1, 7)RLL and NRZ- ASE codes. A video-signal recording experiment using the 8-12 conversi on code achieved at a recording rate of 198 Mb/s and a recording densi ty of 5.8 mu m(2)/bit indicates that this code will make HDTV digital video cassette recorders feasible. The experimental average error rate was 7 x 10(-5), sufficient for HDTV video recording.