Abstract: An antenna apparatus includes: a plurality of first antenna elements to be connected to a first power-feeding point; and a plurality of second antenna elements to be connected to a second power-feeding point, the plurality of first antenna elements and the plurality of second antenna elements being respectively radially arranged, in which one of the first antenna elements, which is selected, is connected to the first power-feeding point through a first switch apparatus and one of the second antenna elements, which is selected, is connected to the second power-feeding point through a second switch apparatus.

Abstract: An antenna apparatus includes: a plurality of first antenna elements to be connected to a first power-feeding point; and a plurality of second antenna elements to be connected to a second power-feeding point, the plurality of first antenna elements and the plurality of second antenna elements being respectively radially arranged, in which one of the first antenna elements, which is selected, is connected to the first power-feeding point through a first switch apparatus and one of the second antenna elements, which is selected, is connected to the second power-feeding point through a second switch apparatus.

Abstract: A most probable path is selected from a number n (where n?2) of paths of state transitions occurring from a first state Sk?j (where k?3 and j?2) at a time k?j into a second state Sk at a time k. The method includes the steps of detecting predetermined combinations of the first and second states Sk?j and Sk defining the n probable paths in a predetermined period j between the times k?j and k, and evaluating the reliability of a read signal, decoded in the period j, by |Pa?Pb|. Pa and Pb indicate the probabilities of state transition of first and second state transition paths in the period j. The first and second state transition paths are estimated to be the most probable and the second most probable, respectively, among the n probable paths defined by the combinations detected.

Abstract: A recording medium comprising a recording area, the recording area includes a first area and a second area, the first area includes a frame area, the frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded, and the second area includes an area of linking frames in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded.

Abstract: A recording medium comprising a recording area, the recording area includes a first area and a second area, the first area includes a frame area, the frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded, and the second area includes an area of linking frames in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded.

Abstract: A method for writing a signal on an optical disk is disclosed. The optical disk comprises a track groove on a recording surface thereof, on which information is recorded along the track groove on a block-by-block basis each said block having a predetermined length and where an identification mark indicating the beginning of each said block, has been formed on the track groove. Writing is started before the identification mark, located at the beginning of at least one block on which the signal should be written, is reached and writing is ended after the identification mark located at the end of the at least one block on which the signal should be written has been passed.

Abstract: A recording medium comprising a recording area, the recording area includes a first area and a second area, the first area includes a frame area, the frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded, and the second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded.

Abstract: An optical disk medium includes a track groove thereon. On the optical disk medium, information is recorded along the track groove on a block unit basis. The block unit has a predetermined length. The block unit having the predetermined length includes a number of sub-blocks that are arranged along the groove. A sub-block mark is provided within each of the sub-blocks and used to identify the sub-block.

Abstract: An optical disc medium comprises a track groove, along which main information is recorded. The track groove is divided into a plurality of blocks. The plurality of blocks each include a plurality of frames. The plurality of frames each include one shape of wobbles indicating sub information, among a plurality of prescribed shapes of wobbles. The plurality of blocks each have address information. The address information is represented by a string of at least one piece of sub information represented by the shape of wobbles of at least one of the plurality of frames.

Abstract: An optical disc medium comprises a track groove, along which main information is recorded. The track groove is divided into a plurality of blocks. The plurality of blocks each include a plurality of frames. The plurality of frames each include one shape of wobbles indicating sub information, among a plurality of prescribed shapes of wobbles. The plurality of blocks each have address information. The address information is represented by a string of at least one piece of sub information represented by the shape of wobbles of at least one of the plurality of frames.

Abstract: An apparatus for reading subdivided information from an optical disk, which comprises a track groove and on which information is recorded along the track groove is disclosed. The apparatus includes an optical head, which irradiates the optical disk with light and generates an electric signal responsive to part of the light that has been reflected from the optical disk, read signal processing means for generating a wobble signal which has an amplitude changing with the wobble pattern from the electric signal, rise value acquiring means for sampling and holding an absolute gradient value of the wobble signal when the signal rises, fall value acquiring means for sampling and holding an absolute gradient value of the wobble signal when the signal falls, and subdivided information detecting means for determining the subdivided information by majority by comparing the values held by the rise and fall value acquiring means with each other.

Abstract: A recording medium comprising a recording area, the recording area includes a first area and a second area, the first area includes a frame area, the frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded, and the second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded.

Abstract: An optical disk includes a groove and a land. Data is recorded on either the land or the groove. A pitch of the groove and a pitch of the land are 0.32 ?m or more. The optical disk has a data efficiency of 80% or more by adopting a format in which other types of user data are added to every plural user data sets. The data efficiency is defined by a ratio of a user data capacity that can be used by a user to a total data capacity of the optical disk.

Abstract: A recording medium comprising a recording area, the recording area includes a first area and a second area, the first area includes a frame area, the frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded, and the second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded.

Abstract: An optical disk includes a land and a groove. The optical disk has a data efficiency of 80% or more. Data is recorded on both the land and the groove. A distance between the center of the land and the center of the groove adjacent to the land is 0.28 ?m or more. Thus, an optical disk having a storage capacity of 25 GB or more can be provided.

Abstract: An optical disc medium 10 having a wobbled track groove 12 includes three wobble patterns including a flat wobble pattern, a positive pulse wobble pattern, and a negative pulse wobble pattern. In the flat wobble pattern, the amplitude of the wobble from the lengthwise direction of the track groove is zero such that the track groove is flat. In the positive pulse wobble pattern, the amplitude of the wobble from the lengthwise direction of the track groove is positive such that the track groove is wobbled in a first direction perpendicular to the lengthwise direction. Further, in the negative pulse wobble pattern, the amplitude of the wobble from the lengthwise direction of the track groove is negative such that the track groove is wobbled in a second direction opposite to the first direction. Then, three data values can be recorded using three distinctive wobble patterns.

Abstract: A most probable path is selected from a number n (where n?2) of paths of state transitions occurring from a first state Sk?j (where k?3 and j?2) at a time k?j into a second state Sk at a time k. The method includes the steps of detecting predetermined combinations of the first and second states Sk?j and Sk defining the n probable paths in a predetermined period j between the times k?j and k, and evaluating the reliability of a read signal, decoded in the period j, by |Pa?Pb|. Pa and Pb indicate the probabilities of state transition of first and second state transition paths in the period j. The first and second state transition paths are estimated to be the most probable and the second most probable, respectively, among the n probable paths defined by the combinations detected.

Abstract: An optical disk medium includes a track groove thereon. On the optical disk medium, information is recorded along the track groove on a block unit basis. The block unit has a predetermined length. The block unit having the predetermined length includes a number of sub-blocks that are arranged along the groove. A sub-block mark is provided within each of the sub-blocks and used to identify the sub-block.

Abstract: An optical disc medium comprises a track groove, along which main information is recorded. The track groove is divided into a plurality of blocks. The plurality of blocks each include a plurality of frames. The plurality of frames each include one shape of wobbles indicating sub information, among a plurality of prescribed shapes of wobbles. The plurality of blocks each have address information. The address information is represented by a string of at least one piece of sub information represented by the shape of wobbles of at least one of the plurality of frames.

Abstract: An optical disc medium comprises a track groove, along which main information is recorded. The track groove is divided into a plurality of blocks. The plurality of blocks each include a plurality of frames. The plurality of frames each include one shape of wobbles indicating sub information, among a plurality of prescribed shapes of wobbles. The plurality of blocks each have address information. The address information is represented by a string of at least one piece of sub information represented by the shape of wobbles of at least one of the plurality of frames.