• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    In the playback of a video disc record employing an FM carrier recording format, a defect compensation system is provided which substitutes delayed video signals for current video signals when a defect is encountered. A phase locked loop including a phase detector and a voltage controlled oscillator is employed in FM detection circuits. A defect detector compares the phase between the oscillator output signal and a signal corresponding to the recovered signal. When the phase difference between these two signals exceeds a certain value, a defect signal is generated to disable the normal signal path of the recovered signal so that the delayed version of the video may be substituted for the current video for the duration of the occurrence of the defect.
    公开号:SU1033016A3
    申请号:SU792820502
    申请日:1979-10-01
    公开日:1983-07-30
    发明作者:Дж.Кристофер Тодд；Хсун Лин Тсан
    申请人:Рка Корпорейшн (Фирма)；
    IPC主号:
    专利说明:

    The invention relates to a recording and reproduction technique on a video disc of television signals and can be used in video playback devices with a frequency-modulated carrier.
    A device is known for detecting defects in reproducing a signal from a video disc, comprising a series-connected signal reproducing unit, a band-pass filter, a limiter and a frequency detector consisting of a zero crossing detector and a pending multivibrator O.
    When using this device, the video signal formulated at the output contains interference caused by the presence of defects in the recording and when reading the recorded signal from the recording media. This noise appears on the reproduced image in the form of black and white spots and stripes.
    The closest to the present invention is a device for detecting a defect in the reproduction of a signal from a video disc, comprising a serially connected signal reproducing unit, a band-pass filter, a limiter and a defect detector C.
    However, the known device, although it provides an indication of defects in the reproduced signal, but due to the presence of broadband filtering in the detector of defects, the reliability of detection of signal defects is low. In addition, the device is difficult and it can not be implemented in the integrated design.
    The purpose of the invention is to improve the reliability of detection of signal defects.
    The goal is achieved by the fact that a phase detector, the first two inputs are introduced into the device for detecting defects during playback of a signal from a video disc containing serially connected signal reproduction unit, a band-pass filter, a limiter and a defect detector. which is connected to the outputs of the limiter, a low-pass filter whose inputs are connected to the outputs of the phase detector, a controlled oscillator whose inputs are connected to the outputs of the low-pass filter, and the outputs under the key to the third and fourth inputs of the phase detector and to the second and third inputs defect detector.
    the fourth input of which is connected to the additional output of the limiter, the defect detector contains the first and second delay triggers and the OR element, the first and second inputs of which are connected respectively to 6 outputs of the first and second delay triggers, and the output of the element OR to the output of the defect detection signal controlled by The first and second delay trigger inputs are the first and fourth defect detector inputs, respectively, and the clock inputs of the first and second delay triggers are the corresponding the second and third inputs of the defect detector.
    Figure 1 shows the structural electrical circuit of the device for unloading defects when playing a signal from a video disc; 2, time diagrams of voltages in the presence of a signal with a reduced frequency; FIG. 3 shows time diagrams of voltages in the presence of a signal with an increased frequency.
    The device for detecting defects during playback of a signal from a video disc contains a signal playback unit 1, a band-pass filter 2, a limiter 3, a defect detector 4, which consists of the first and second triggers 5, and 5.2 delays, the OR 6 element and the converter 7, the phase detector 8, low pass filter 9 and controlled oscillator 10.
    The device for detecting defects when playing back a signal from a video disc works as follows.
    The signal recorded on the video disc is reproduced by the signal reproducing unit 1. The frequency modulated signal passes through a bandpass filter 2, the bandwidth that spans the range of the carrier deviation of the image. In limiter 3, parasitic amplitude modulation of the mastically modulated signal is suppressed.
    Phase detector 8 compares the phase of the signal supplied from limiter 3 to the phase of the signal supplied from controlled oscillator 10. The output signal of phase detector 8 is fed to controlled oscillator 10 through low-pass filter 9 and is used to change the frequency of controlled oscillator 10 in this way so that the phase difference of the signals supplied by the phase detector 8 is kept constant within a stable operating mode. The defect detector k analyzes the phase relationship between the signals applied to it. Initially, the phase difference between the input signals supplied is set to 90. Detector 4 is designed so that the defect indication signal with a fixed reference level is output, the phases between the supplied signals when the difference is within the initial phase ratio, i.e. there is a phase separation interval of .0-180 between signals fed to a defect detector, within which the defect detector generates a reference level signal (e.g. 5 V}. When the phase difference between the signals fed to the defect detector is out of the specified range, i.e., when the phase difference falls within the interval of 180-ZbO °, it generates an indication signal of the defect in the form of an rmpulse, which exceeds the duration of the time interval from the moment when the selected phase difference for the first time exceeded the specified interval until the phase difference It is possible to note that a defect indication pulse occurs at a quite definite phase relation between the signal related to the oscillations of the reconstructed carrier and the signal of the controlled generator 10. The signal from limiter 3 causes the phase difference to go beyond the stable interval. 0-180 ° when there is a significant rapid departure of the FM carrier from a given deviation interval. The low-pass filter 9 is designed in such a way that it creates a defined one. degree of inertia in the response of the phase locking circuit. Thus, while the controlled generator 10 is mainly controlled to track the signal from the output of the limiter 3, the tracking will occur 1 4 to go at a speed less than the changes that occur in you: sig / nal limiter 3 due to defects. The bandwidth of the low-pass filter 9 is such that it causes a signal delay from 200 to not. This delay is sufficient to detect a defect in the defect detector. The signal from the first output of the controlled oscillator 10 (Fig. 2a and Za is fed to the clock input of the first trigger 5.1) delays on the control input of which the signal comes from the first output of the limiter 3 (Figs. 26 and 36;;; The signal from the second output of the controlled generator 10 (Figs. 2d and 3g) is fed to the clock input of the second trigger 5.2. delay on the pack (this is the input of which is the signal from the auxiliary output of the limiter 3 (fig. and 35) stumbles. In the presence of a defect, characterized by a lower reproduced signal frequency (figv) at the output of the 5.1 and 5.2 delays, the delays will act according to the diagrams 2e and 2g. The logical summation of these voltages in the element OR 6 leads to the appearance of a signal on the output of an indication of a severe condition of a defect (figure 2). The voltage level of the signal of indication of a defect is interrupted in converter 7 to further use. In a similar way, a defect indication signal (Fig. 3) is generated. The increased part of the reproduced signal. (Fig. 3). In this case, the form of the voltages at the outputs of the flip-flops and 5.2 zaddersk and the element OR 6 is illustrated by the diagrams in Figs. Ze, 33f and 3.. Thus, the device for detecting defects during playback of a signal from a video disc makes it possible to increase the reliability of detection of signal defects and allows it to be implemented in an integral design, which distinguishes the proposed device from the prototype.
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    权利要求:
    Claims (1)
    [1]
    DEVICE DETECTION DEVICE WHEN PLAYING A SIGNAL FROM A VIDEO DISC, comprising a signal reproducing unit, a bandpass filter, a limiter and a detector, characterized in that, in order to increase the reliability of detection of signal defects, a phase detector is introduced, the first two inputs of which are connected to the outputs of the limiter, a filter low-frequency, the inputs of which are connected to the outputs of the phase detector, a controlled generator, the inputs of which are connected to the outputs of the low-pass filter, and the outputs are connected to the fourth and fourth inputs of the phase detector AND to the second and third inputs of the defect detector, the fourth input of which is connected to the additional output of the limiter, while the defect detector contains the first and second delay triggers and an OR element, the first and second inputs of which are connected respectively to the outputs of the first and second delay triggers, and the output of the element I OR is the output of the defect detection signal, the control inputs of the first and second delay triggers are the first and fourth inputs of the detectors, respectively defect torus and the synchronizing inputs of the first and second delay triggers are the second and third inputs of the defect detector, respectively.
    ; and 1033016
    1 1033016 2
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    引用文献:
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    US3582809A|1968-09-06|1971-06-01|Signetics Corp|Phased locked loop with voltage controlled oscillator|
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    JPS5550640B2|1973-03-09|1980-12-19|
    AR207776A1|1974-06-06|1976-10-29|Rca Corp|ARRANGEMENT TO PLAY BACK A RECORDING OF SUCCESSIVE COLOR IMAGES|
    US4001496A|1974-06-06|1977-01-04|Rca Corporation|Defect detection and compensation apparatus for use in an fm signal translating system|
    US3967311A|1974-11-12|1976-06-29|Rca Corporation|Velocity correction for video discs|
    JPS5440331B2|1975-03-05|1979-12-03|
    GB1536851A|1975-03-10|1978-12-20|Rca Corp|Video carrier wave defect detection and compensation|
    NL7503049A|1975-03-14|1976-09-16|Philips Corp|DEVICE FOR COMPENSATION OF SIGNAL FAILURES IN AN ANGLE MODULATED SIGNAL.|US4286283A|1979-12-20|1981-08-25|Rca Corporation|Transcoder|
    JPS6325424B2|1980-07-03|1988-05-25|Victor Company Of Japan|
    US4376289A|1980-10-27|1983-03-08|Rca Corporation|Self-enabling dropout corrector|
    US4327431A|1980-11-07|1982-04-27|Rca Corporation|Video disc player with variable offset RFI reduction circuit|
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    法律状态:
    优先权:
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