{'fraction_non_alphanumeric': 0.02556237218813906, 'fraction_numerical': 0.006134969325153374, 'mean_word_length': 4.594285714285714, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Track Center Servo and Radial Tilt Servo System for a Digital Versatile Rewritable Disc (DVD-RAM)

In the push-pull tracking error signal, which is generally used for rewritable discs, detection error occurs due to disc radial tilt. We have developed a track center detection method in which the center of a track is accurately detected using the complementary allocated pit address (CAPA) of a digital versatile rewritable disc (DVD-RAM). The track center servo corrects the tracking deviation caused by the detection error. We have also developed a method for detecting the disc radial tilt based on the fact that the level of the push-pull tracking error signal indicates the amount of disc radial tilt when the track center servo is in operation. The developed servo system was introduced in a 4.7-G byte DVD-RAM disc drive, and it has been confirmed that jitter deterioration during reproduction was reduced to 0.5% or lower in the range of ±0.5 degree of disc radial tilt.