Abstract: A decoding device includes: an interference canceling circuit (104) which extracts, from states of 2K-number (where K is a natural number) of detected signals that are likely within a range of K bit width where an interference between bits of the digital information occurs due to predetermined frequency characteristics, most likely 2M-number (where M is a natural number) of detected signals respectively corresponding to states of 2M-number of detected signals which exist within a range of M bit width that is included in the range of K bit width; and a Viterbi decoding circuit (105) which generates a decoded signal by calculating differences between the 2M-number of detected signals extracted by the interference canceling circuit (104) and expectation signals respectively corresponding to the 2M-number of detected signals and also by selecting a transition sequence of a state of a detected signal for which the calculated difference is smallest.

Abstract: A "hybrid" encoder has a characteristic action suitable for substantially full complementary playback in an audio signal transmission or recording system using decoders designed for one type complementary encode/decode system while permitting compatible decoding with decoders designed for use with another type complementary encode/decode system, or playback without any special decoders at all. The hybrid encoder is a series or parallel arrangement of two encoders that are modifications of standard encoders used in the two systems. In the preferred embodiments the two systems are A-type noise reduction and spectral recording. A variable degree of hybrid encoding is provided by varying the characteristic controlling circuit parameters in the two encoders, or in a preferred embodiment, by providing a variable combining arrangement that selects selects from the outputs of a hybrid encoder and an unmodified encoder (spectral recording).

Abstract: An optical information processing method and an apparatus therefor for information recording on or information readout from a recording medium by converging a light beam onto the recording medium, in which the wave form equalization characteristic of the signal upon information recording or information readout is controlled in accordance with the information on the state of focus of the light beam on the recording medium.

Abstract: Method and apparatus for producing a mechanically reproducible recording in a metal disk record by operating an electrically excited cutting stylus to cut a modulated groove in the record, orienting the cutting stylus to be driven at a tracking angle of less than 5.degree., and electronically compensating recording distortions caused by this tracking angle.

Abstract: A time compression/expansion audio reproduction system of the type that provides pitch correction by repetitive variable time delay achieves improved performance by separating the reproduced signal from a recording into components which are separately delayed. For studio quality reproduction the signal is separated into contiguous frequency bands which are each delayed synchronously and the processing noise in each band is eliminated by filtering each band signal after delay to eliminate high frequency components. Bandpass filtering prior to recombination as well as blanking and amplitude compression and expansion are also disclosed.

Abstract: A direct-read-after-write optical recording disc having a pair of transparent, disc-shaped members, each being formed with integral inner and outer ring-shaped bosses on one of its sides. A thin recording layer of a light-sensitive material is coated on each disc-shaped member, in a shallow annular recess formed between its two ring-shaped bosses, and the two members are disposed in a coaxial relationship, with their respective bosses in abutment with each other, whereby the two recording layers are located within a sealed, annular chamber.