Channel coding scheme for 34 in HDTV digital VCR

摘要

The authors have developed an experimental 34 in HDTV digital videocassette recorder (VCR). The VCR can record HDTV digital base-band signals for more than 64 min on a 34 in metal particle (MP) tape. An eight-to-eight modulation (88M) scheme has been developed for this VCR to realize high-density recording. In order to suppress sufficiently the low-frequency components and reduce the occurrence probability of long-run-lengths for the recording data sequence, a new conversion table and bit-rearrangement method have been introduced in this modulation scheme. This conversion table has been particularly structured to reduce run-length using the bit-rearrangement process. Three kinds of typical HDTV images were used to evaluate the performance compared with the scrambled-NRZ method. The run-length distribution and the frequency spectrum were calculated for each image. The results showed that the occurrence probability of long-run-lengths were well reduced and the low-frequency components along with the DC component were sufficiently suppressed. Cross-talk interferences and overwriting noises were also found to be much less than those for the scrambled-NRZ method.