Abstract: In a demodulator for a digital FM signal, the received digital FM signal is verified at the data bit boundaries for inversion to detect errors. If an uninverted data bit boundary is detected, those sections of the digital FM signal just preceding and just following the uninverted data bit boundary are modified thereby generating two modified signals. Using the error detecting code included in the digital FM signal, the two modified signals are evaluated to determine which modification corrects the errors and the modified signal with the correct modification is selected.

Abstract: In a demodulator for a digital FM signal, the received digital FM signal is verified at the data bit boundaries for inversion to detect errors. If an uninverted data bit boundary is detected, those sections of the digital FM signal just preceding and just following the uninverted data bit boundary are modified thereby generating two modified signals. Using the error detecting code included in the digital FM signal, the two modified signals are evaluated to determine which modification corrects the errors and the modified signal with the correct modification is selected.

Abstract: A frequency modulated signal, which is expected to have level inversions at data bit boundaries, and which is produced by the reflection of a laser beam from a wobbled spiral groove on a disk-shaped recording medium is detected. The frequency modulated signal is demodulated and its signal level at the location just after the absence of a level inversion is corrected. The position of a movable recording/reproducing head is determined in response to the demodulated FM signal; and data is recorded on or reproduced from the recording medium at the determined position.

Abstract: A rotation control circuit for a Hall motor of reduced-size and suppressed irregular rotation and having a controller that stores in a memory circuit data indicative of an irregular magnetization of a rotor magnet derived from a change of the magnetic field of the rotor magnet detected by a Hall element as an irregular rotation informationsignal, in which the irregular rotation information signal is input to a speed servo loop of the Hall motor, whereby the change of magnetic field of the rotor magnet is used as an FG signal to form a speed servo circuit.

Abstract: A tracking control apparatus for use with an optical information reproducing system in which information to be reproduced is formed on a surface of a recording carrier with a substantially circular record track, and a light beam is incident on the surface for reading the information, the apparatus including a photo-detector for detecting the light beam reflected from the recording carrier and generating an information signal and a first tracking error signal, the first tracking error signal being responsive to deviations by the light beam from the center of the record track; a tracking control apparatus receiving the first tracking error signal for adjusting the position of the light beam in response thereto; a measuring device for generating a second tracking error signal indicative of the eccentricity of the record track; and a circuit for supplying the second tracking error signal to the tracking control apparatus to adjust the position of the light beam in response thereto.

Abstract: Disclosed is a muting circuit, in which the generation of click noise is prevented in that the muting operation is caused to occur at an instant when the instantaneous level (i.e., waveform level) of the input audio signal becomes zero for the first time since the appearance of a muting signal.

Abstract: Disclosed is a digital signal processing circuit, which can process digital data of at least two different data formats where one word consists of respectively of m and n bits (m and n being positive integers and m>n), for instance 16 and 14 bits, resides in that serial data of the data format where one word consists of m bits (for instance 16 bits) is rearranged into a form conforming to the data format where one word consists of n bits (for instance 14 bits) and that processing (for instance T matrix calculation) is effected according to a bit clock corresponding to the difference in the bit number between m and n, thereby obtaining data conforming to the data format where one word consists of n bits.

Abstract: Disclosed is a muting circuit, in which the generation of click noise is prevented in that the muting operation is caused to occur at an instant when the instantaneous level (i.e., waveform level) of the input audio signal becomes zero for the first time since the appearance of a muting signal. .Iadd.A muting-off circuit is also disclosed for turning off the muting circuit. .Iaddend.