摘要:
A control apparatus for a recording medium drive motor in a digital information reproducing apparatus. The apparatus controls a rotation speed of the recording medium at a prescribed constant linear velocity in using a reproduced signal from the medium without employing a detector for detecting the position of a pick-up device used therein and without being affected by an unexpected level change of the reproduced signal. The apparatus includes a motor for driving the recording medium having a digital information recorded thereon in the form of a run length limited pulse code modulation, a pick-up for reproducing a digital signal from the recording medium driven by the motor, a detector for detecting a predetermined limited cycle length of the digital signal from the reproduced signal by the pick-up, and a controller for controlling the rotation speed of the motor so that the limited run length of the reproduced digital signal is kept at a predetermined value.
摘要:
A tracking control system for an optical disc information reproducing apparatus in which information stored in an optical disc as a series of recesses or pits arranged in concentric tracks or in a single spiral track is read out during rotation of the optical-disc by a scanning spot of a light beam, the system comprising a light source for generating the light beam used for scanning the track, means for applying the scanning spot of the light beam to a selected track location, a transducer for converting an optical signal detected by the scanning spot into an electric signal bearing a tracking error information, means for controlling the scanning spot applying means in response to the tracking error information signal, thereby causing the scanning spot to scan the selected track location accurately, means for transferring the tracking error information signal to the controlling means, a transfer characteristics of the transferring means being variable, means for limiting a slew rate of the tracking error information signal, means for subtracting an output of the slew rate limiting means from the tracking error information signal, and means for lowering the transfer characteristics of the controlling means in response to an output of the subtracting means, thereby causing the controlling means being irresponsive to the tracking error information signal.
摘要:
A digital waveform conditioning circuit for restoring a deformed digital signal into its original rectangular waveform, comprising an input terminal supplied with the deformed digital signal, a circuit for generating a reference signal by combining positive and negative voltage components rectified from positive and negative cycles of the deformed signal, a comparator for comparing the deformed signal with the reference signal, a circuit for holding an output signal of the comparator for a period controlled by a clock signal for synchronizing the output signal with the original rectangular signal, and an output terminal for receiving the output of the holding circuit.
摘要:
A circuit is disclosed which is applied for a digital audio disk (DAD) system for detecting a maximum inverting period of a digital audio signal optically read out from the DAD. The audio signal is prestored in the DAD so as to have the maximum and minimum inverting periods specially set by an eight to fourteen modulation (EFM). The detection circuit includes an edge detector for detecting pulse edges of the digital audio signal, a counter for counting pulse edge intervals on the basis of a modulating clock signal, a counter type register, and a comparator. When the register contents of the counter type register is smaller than the count value of the counter, the comparator produces a pulse signal by which said register updates the contents of the register by "1". Repeating this operation, a maximum inverting period value of the digital audio signal is obtained in a fixed period of time.
摘要:
A data reproduction circuit, which can be used for reproducing audio data from an optical disc, includes a phase-locked loop which has a circuit for detecting polarity inversions of the input signal, a circuit for comparing the phases of a polarity inversion signal with a reference signal, and circuitry for generating an output clock signal which is phase-locked with the input signal, that clock being used to strobe the input signal to remove fluctuation and jitter from the input signal.
摘要:
A data extracting circuit for converting an analog signal derived from a D.C. component-free modulated digital signal stored on a recording medium, into a D.C. component-free digital signal with a comparator for comparing the analog signal with a reference signal to provide a compared signal. A phase inverter receives the compared signal and provides a first signal component which is in-phase with the compared signal, and a second signal component which is phase-inverted with respect to the compared signal. A clipping circuit limits the amplitude level of the first and second signal components to a predetermined level and provides first and second limited signal components. An integrating circuit separately integrates the first and second limited signal components and provides first and second integrated signals. An error amplifying circuit determines the difference between the first and second integrated signals and provides a signal corresponding to this difference to the comparator as the reference signal. The D.C. component-free digital output signal is derived from the first signal component.
摘要:
The invention relates to a motor control circuit of a data reproduction apparatus, which drives a disk motor to reproduce a data signal recorded together with a sync signal on a recording medium so as to control the disk motor in accordance with a reproduced sync signal. The frequency and phase components of the reproduced sync signal are detected, and first and second motor control signals are produced in accordance with frequency and phase detection signals, respectively. A control circuit detects whether or not the frequency detection signal falls within a predetermined range. If it is determined that the frequency detection signal does not fall within the predetermined range, the second motor control signal is kept at a predetermined value.
摘要:
A pulse code modulation signal processor extracts data words from a serial data stream. The signal processor includes a serial-to-parallel converter to convert the data stream into parallel data words, a de-interleave circuit to add different delays, and thus synchronize with each other, the extracted data words, a circuit for forming an error pointer from the data words, an error pointer comprising data word error pointers each indicating the presence of an error in a different data word, an error pointer shift register for synchronizing the error pointer with the data words from the de-interleave means, and an error detector and corrector.
摘要:
A PCM (pulse code modulation) signal recording system including a first signal processor for processing a recording signal into a predetermined PCM signal, a second signal processor for processing a reproduced PCM signal into a recording signal, a first clock signal generator generating a master clock signal, a second clock signal generator generating at least one recording clock signal from the master clock signal, the recording clock signal is supplied to the first signal processor, a third clock signal generator generating at least one reproducing clock signal from the master clock signal, the reproducing clock signal is supplied to the second signal processor, a comparator digitally comparing the phases of the second and third clock signals and producing a control signal, and a controller receiving the control signal and controlling the second or third clock signal so that they are synchronized.
摘要:
An input data signal, in which n data words W.sub.1 to W.sub.n and two check words P and Q are treated as one data block, is processed by P and Q decoding circuits. The decoded data S.sub.1 and T.sup.i-(n+1) S.sub.2 from the decoding circuits are added to each other in an adder to generate S.sub.1 +T.sup.i(n+1) S.sub.2 which is in turn selected by a gate circuit in accordance with a selection signal. The selection signal is supplied from an M matrix generator (MG) embodied as a linear feedback shift register for H(x)=X.sup.m +X.sup.g +1. The initial value of the linear feedback shift register is set in accordance with the error word data derived from an error word control circuit and the order of the data to be decoded. The decoded data sequentially selected from the gate circuit are added by an adder to be the data W.sub.je to be decoded, while at the same time those are added to the S.sub.1 by an adder to be the data W.sub.ie to be decoded. The data W.sub.je and W.sub.ie is added to the corresponding data words W.sub.i and W.sub.j of the input data signal having passed through a one-block delay circuit by an adder, whereby the error data are corrected.