Abstract: A circuit in an optical read/write device for protecting synchronizing patterns is proposed. The protection circuit utilizes a clock with constant frequency as a reference clock. The circuit for protecting synchronizing patterns of this present invention includes a SYNC detector, a frame period counter, a valid-frame-period judgment unit, a frame period memory, a window generator, a real SYNC judgment unit, a SYNC lock judgment unit, and a SYNC signal generator. The circuit counts the pulse number of a reference clock with constant frequency for each frame to get a constant frame period. Then, the circuit can correctly interpolate the lost frame SYNC signal immediately by counting the reference clock, when the disk is defected.

Abstract: A jitter measuring method and device, which is capable of measuring jitters in serial digital signal without high-frequency reference clock. The jitter measuring device comprises a rough length measuring unit for measuring rough length for each pulse of the serial digital signal according to a reference clock, and a phase error measuring unit for measuring the phase errors between the edges of the reference clock and the serial digital signal by multi-phase clocks, which are generated by a multi-phase generator according to the reference clock. The jitter measuring device computes the precise length according to the rough length and the phase error, and measures the jitters from the precise length by filters.

Abstract: A jitter measuring method and device, which is capable of measuring jitters in serial digital signal without high-frequency reference clock. The jitter measuring device comprises a rough length measuring unit for measuring rough length for each pulse of the serial digital signal according to a reference clock, and a phase error measuring unit for measuring the phase errors between the edges of the reference clock and the serial digital signal by multi-phase clocks, which are generated by a multi-phase generator according to the reference clock. The jitter measuring device computes the precise length according to the rough length and the phase error, and measures the jitters from the precise length by filters.

Abstract: A circuit in an optical read/write device for protecting synchronizing patterns is proposed. The protection circuit utilizes a clock with constant frequency as a reference clock. The circuit for protecting synchronizing patterns of this present invention includes a SYNC detector, a frame period counter, a valid-frame-period judgment unit, a frame period memory, a window generator, a real SYNC judgment unit, a SYNC lock judgment unit, and a SYNC signal generator. The circuit counts the pulse number of a reference clock with constant frequency for each frame to get a constant frame period. Then, the circuit can correctly interpolate the lost frame SYNC signal immediately by counting the reference clock, when the disk is defected.

Abstract: A jitter measuring method and device, which is capable of measuring jitters in serial digital signal without high-frequency reference clock. The jitter measuring device comprises a rough length measuring unit for measuring rough length for each pulse of the serial digital signal according to a reference clock, and a phase error measuring unit for measuring the phase errors between the edges of the reference clock and the serial digital signal by multi-phase clocks, which are generated by a multi-phase generator according to the reference clock. The jitter measuring device computes the precise length according to the rough length and the phase error, and measures the jitters from the precise length by filters.

Abstract: A jitter measuring method and device, which is capable of measuring jitters in serial digital signal without high-frequency reference clock. The jitter measuring device comprises a rough length measuring unit for measuring rough length for each pulse of the serial digital signal according to a reference clock, and a phase error measuring unit for measuring the phase errors between the edges of the reference clock and the serial digital signal by multi-phase clocks, which are generated by a multi-phase generator according to the reference clock. The jitter measuring device computes the precise length according to the rough length and the phase error, and measures the jitters from the precise length by filters.