KR0156850B1 - Ntsc/pal noise removing circuit of laser disc player system - Google Patents

Abstract

The present invention relates to a noise canceling circuit in an NTSC / PAL combined laser disk player system, and more particularly, to an NTSC / PAL combined digital noise canceling circuit that can be used to remove noise in response to an NTSC / PAL signal.

In the laser disc player system, the NTSC signal or PAL signal on the laser disc is separated from the luminance signal and the color signal, and the noise is removed by detecting the correlation between adjacent samples using only the luminance signal. When the correlation is detected, the sample interval is adjusted freely to remove perfect noise.

Description

NTSC / PAL Combined Noise Canceling Circuit of Laser Disc Player System

1 is a conventional NTSC signal noise cancellation circuit.

2 is an NTSC / PAL signal combined noise cancellation circuit applied to an embodiment of the present invention.

3 is a frequency spectrum diagram of a color signal according to the present invention;

4 is an NTSC / PAL combined noise cancellation circuit applied to another embodiment according to the present invention.

* Explanation of symbols for main parts of the drawings

32, 38: first to second band pass filter 34, 40, 48: first to third delay

36, 42, 54: 1st-3rd adder 44, 46: 1st-2nd MUX

50: adaptive FIR filter 52: pixel correlation detection and coefficient generator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise canceling circuit in an NTSC / PAL combined laser disc player system, and more particularly, to an NTSC / PAL combined digital noise canceling circuit which is used in combination to remove noise corresponding to an NTSC / PAL signal.

In general, the NTSC / PAL combined laser disc player system picks up a composite video signal on a disc and detects NTSC or PAL signals having different frequency bands from the FM demodulated signal. In this case, image quality deterioration does not occur only when the noise carried in the NTSC or PAL signal is removed and processed. However, a circuit for removing noise of the NTSC signal of the conventional laser disc player system is shown in FIG. When the composite video signal is input through the input terminal P1, the pixel correlation detection and coefficient generator 20 compares the current video signal with four signals before and after the four sample pixels by the 4fsc clock signal, and does not matter if it is not within the set range. To judge. However, if it is within the set range, it is determined that there is a correlation, and a corresponding coefficient is generated and output to the adaptive FIR filter 10. In this case, the adaptive FIR filter 10 for inputting the composite video signal receives the 4fsc clock signal and outputs the FIR filter according to the presence or absence of the coefficient output from the pixel correlation detection and coefficient generator 20. Therefore, in the adaptive FIR filter 10, since the composite video signal compares all four sample pixels in synchronization with the 4fsc clock, the color component is not damaged at all, and only the noise component in the luminance signal is removed and output.

In addition, when there is no correlation, the correlation coefficient is not generated in the pixel correlation detection and coefficient generator 20, and in this case, the adaptive FIR filter 20 outputs the composite image signal as it is.

The conventional noise canceling circuit as described above cannot be used for both NTSC / PAL because the clock signal must be supplied at a multiple of fsc. That is, it is impossible to simultaneously protect the 3.75 MHZ pilot signal and the 4.43 MHZ color signal when the PAL signal is used in the PAL laser disc player system.

In addition, since the correlation must be detected by skipping four samples in order to protect the color signal, there is a problem that noise is not removed in the correlation detection between adjacent samples.

SUMMARY OF THE INVENTION An object of the present invention is to provide an NTSC / PALFM combined noise canceling circuit capable of combining and removing noise in response to an NTSC / PAL signal in a laser disc player system.

The present invention for achieving the above object is the first luminance / color separation means for separating the luminance signal (Y1) and the color signal (C1) by inputting the NTSC composite video signal, and the luminance signal (Y2) by inputting the PAL composite video signal ) And second luminance / color separation means for separating the color signal (C2), control means for discriminating the input state of the NTSC signal or the PAL signal and generating an NTSC / PAL selection control signal, and the first to second luminance. And a signal selecting means for selectively outputting the luminance signal and the color signal outputted from the color separating means by the NTSC / PAL selection control signal outputted from the control means, and the luminance signal selectively outputted from the signal selecting means. Pixel correlation detection and coefficient generation means for detecting a correlation between adjacent pixels by a clock signal and generating a correlation coefficient when it is within a set range, a luminance signal selected and output from the signal selection means, and And an adaptive FIR filter means for inputting the correlation coefficient output from the pixel correlation detection and coefficient generation means to remove noise components in the system clock signal.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is an NTSC / PAL signal combined noise cancellation circuit applied to an embodiment according to the present invention. The first band pass filter 32 extracts and outputs a color signal C1 by inputting an NTSC composite video signal. A first delay unit 34 for inputting an NTSC composite video signal and outputting a predetermined time delay, and a color signal C1 extracted from the first band pass filter 32 to extract the luminance signal Y1; One adder 36, a second band pass filter 38 for inputting the PAL composite video signal to extract and output the color signal C2, and a second delay unit for delaying the predetermined time by inputting the PAL composite video signal; A second adder 42 for adding the color signal C2 extracted from the second band pass filter 38 to extract the luminance signal Y2, and the first band pass filter 32; NTSC / PAL of the control unit by inputting the color signal C1 output from the color signal C2 and the color signal C2 output from the second band pass filter 38. A first MUX 44 for selectively outputting one by a selection control signal, a luminance signal Y1 output from the first adder 36, and a color signal Y2 output from the second adder 42; A second MUX 46 for selectively outputting one by the NTSC / PAL selection control signal of the control unit; a third delay unit 48 for delaying a predetermined time output of the color signal selected and output from the first MUX 44; A pixel correlation detection and coefficient generator 52 for inputting a luminance signal selectively outputted from the second MUX 46 to detect correlation between adjacent pixels by a system clock signal, and generating a temporary correlation coefficient within a set range; An adaptive FIR filter 50 for inputting a luminance signal selected from the 2MUX 46 and a correlation coefficient from the pixel correlation detection and coefficient generator 52 to remove noise components from the system clock signal and output the noise component; The noise is removed from the type FIR filter 50 Adding the signal of the third delay unit delays the output color signal from an 48 and is composed of a third adder (54) for outputting a composite video signal which noise is removed.

The first band pass filter 32, the first delay unit 34, and the first adder 36 of the above configuration separate the luminance signal Y1 and the color signal C1 to process the NTSC video signal. do.

A portion composed of the second band pass filter 38, the second delay unit 42, and the second adder 42 separates the luminance signal Y2 and the color signal C2 to process the PAL image signal.

The first-second MUXs 44 and 46 operate in conjunction to operate the separated NTSC luminance signal Y1 and color signal C1 and the separated PAL luminance signal Y2 and color signal C2. Select and print.

3 is a frequency spectral diagram of a color signal according to the present invention, which is shown in FIGs. 3A and 3B, FIG. 3A is a frequency spectrum diagram of an NTSC color signal, and FIG. 3B is a frequency spectrum diagram of a PAL color signal.

One preferred embodiment of the present invention will be described in detail with reference to FIGS.

First, when the NTSC composite video signal is input through the input terminal P11, the first band pass filter 32 performs band pass filtering to output the color signal C1 of 3.58 MHZ as shown in FIG. 3a to the first adder 36 and the first MUX. Output to (44). At this time, the first delay unit 34 for inputting the NTSC composite video signal outputs the input signal by delaying the input signal for a predetermined time. Then, the first adder 36 adds the NTSC composite video signal delayed output from the first delayer 34 and the color signal C1 output from the first band pass filter 32 to add the luminance signal Y1. Is extracted and output to the second MUX 46. At this time, the control unit (not shown) can recognize NTSC / PAL detection as published in 1993 Patent Application No. 22933 filed by the applicant of the present application, thereby generating a control signal for selecting the NTSC signal, thereby generating the first-second MUX. It is applied to the selection terminal S of (44, 46). Accordingly, the first MUX 44 selects the signal input to the input terminal A and outputs the color signal C1 output from the first band pass filter 32. The second MUX 46 selects the signal input to the input terminal A and outputs the luminance signal Y1 output from the first adder 36. The pixel correlation detection and coefficient generator 52 for inputting the luminance signal Y1 selectively outputted from the second MUX 46 detects the correlation between adjacent samples by a system clock signal and correlates the signal within the set correlation range. The coefficients are generated and output to the adaptive FIR filter 50. Then, the adaptive FIR filter 50, which inputs the luminance signal Y1 and the correlation coefficient selected and output from the second MUX 46, inputs a system clock signal to filter and output noise. The video signal is picked up and output. In this case, since only the luminance signal is processed during correlation detection, the comparison sample interval can be adjusted as desired, so that the clock signal is not limited. In addition, the color signal C1 selected and output from the first MUX 48 is delayed by the third delayer 48 for a predetermined time and output to the third adder 54. As a result, the third adder 54 adds the luminance signal from which the noise is removed from the adaptive FIR filter 50 and the color signal C1 delayed by the predetermined time from the third delayer 54 to remove the noise. Output composite video signal.

On the other hand, when the PAL composite video signal is input through the input terminal P11, the second band pass filter 38 performs band pass filtering and band pass filters the 3.75 MHz and 4.43 MHz as shown in FIG. 3b. The input signal is delayed for a predetermined time and output. Then, the second adder 42 adds the PAL composite video signal delayed output from the second delayer 40 and the color signal C2 output from the second band pass filter 38 to obtain a luminance signal Y2. Is extracted and output to the second MUX 46. At this time, since the control unit (not shown) can recognize NTSC / PAL detection, a control signal for selecting a PAL signal is generated and applied to the selection terminal S of the first to second MUXs 44 and 46. Accordingly, the first MUX 44 selects the signal input to the input terminal B, and outputs the color signal C2 output from the second band pass filter 38. The second MUX 46 selects the signal input to the input terminal B, and outputs the luminance signal Y2 output from the second adder 42. The pixel correlation detection and coefficient generator 52 for inputting the luminance signal Y2 selectively outputted from the second MUX 46 detects the correlation between adjacent samples by the system clock fsc signal and applies the signal within the set correlation range. A correlation coefficient is generated and output to the adaptive FIR filter 50. Then, the adaptive FIR filter 50, which inputs the luminance signal Y2 and the correlation coefficient selected and output from the second MUX 46, inputs a system clock signal to filter and output noise. In this case, since only the luminance signal is processed during correlation detection, the comparison sample interval can be adjusted as desired, so that the clock signal is not limited. In addition, the color signal C2 selected and output from the first MUX 48 is delayed by the third delayer 48 for a predetermined time and output to the third adder 54. As a result, the third adder 54 adds the luminance signal Y2 from which the noise is removed from the adaptive FIR filter 50 and the color signal C2 delayed by the predetermined time from the third delayer 54, thereby adding noise. Outputs the composite video signal from which the? Here, the first to third delay units 34, 40, and 48 are used to compensate for the time difference between signals when added, and only a delay time may be set.

The system clock used in the present invention can be implemented using the same signal regardless of the NTSC signal and the PAL signal. That is, noise removal can overcome various constraints caused by the prior art by performing processing by separating the luminance and the color signal so as to use only the luminance signal irrespective of the color signal.

4 is an NTSC / PAL combined noise cancellation circuit applied to another embodiment according to the present invention. The low pass filter 62 extracts and outputs a luminance signal by performing low pass filtering by inputting a composite video signal, and a composite video signal. Inputs a delayed output delayed by a predetermined time and outputs the fourth delay unit 64, the composite image signal delayed output from the fourth delay unit 64 and the luminance signal Y3 output from the low pass filter 62. A fourth adder 66 for adding and extracting and outputting the color signal C3, and a fifth delayer 68 for delaying and outputting the color signal C3 output from the fourth adder 66 for a predetermined time; And a pixel correlation detection and coefficient generator 70 for inputting a luminance signal Y3 output from the low pass filter 62 to detect correlation between adjacent pixels by a system clock signal to generate a temporary correlation coefficient within a set range. And output from the low pass filter 62. An adaptive FIR filter 72 for inputting a luminance signal and a correlation coefficient output from the pixel correlation detection and coefficient generator 52 to remove noise components from a system clock signal, and output the noise component to the system clock signal; And a fifth adder 74 which adds a luminance signal from which noise is removed from the color signal delayed from the fifth delay unit 68 and outputs a composite video signal from which noise is removed.

Referring to FIG. 4 described above, another preferred embodiment of the present invention will be described in detail.

First, when the composite video signal is input through the input terminal P11, the low pass filter 62 performs low pass filtering in the 2.5 MHZ band to convert the luminance signal Y3 into the fourth adder 66 and the adaptive FIR filter 70. Output to the pixel correlation detection and coefficient generator 70. At this time, the fourth delay unit 64 for inputting the composite video signal outputs the input signal by delaying the input signal. Then, the fourth adder 66 extracts the color signal C3 by adding the composite video signal delayed from the fourth delayer 64 and the luminance signal Y3 output from the low pass filter 62. Output to the fifth delay unit (68). The fifth delay unit 68 delays the color signal C3 output from the fourth adder 66 by a predetermined time and outputs the color signal C3 to the fifth adder 74. The color signal C3 is a video signal of 2.5 MHz or more, and the luminance signal Y3 is a signal of 2.5 MHz or less.

On the other hand, the pixel correlation detection and coefficient generator 70 inputting the luminance signal Y3 selected and output from the low pass filter 62 detects the correlation between adjacent samples by a signal which is a system clock, and thus the signal within the set correlation range. A correlation coefficient is generated and output to the adaptive FIR filter 72. Then, the adaptive FIR filter 70 which inputs the luminance signal Y3 outputted from the low pass filter 62 and the correlation coefficient inputs a system clock signal to filter and output noise. Here, since only the luminance signal is processed during correlation detection, the comparison sample interval can be adjusted as desired, so that the clock signal is not limited.

Therefore, the fifth adder 74 adds a luminance signal from which noise is removed from the adaptive FIR filter 70 and a color signal C3 delayed by a predetermined time from the fifth delayer 68 to remove noise. Output video signal.

As described above, in the laser disc player system, the NTSC signal or the PAL signal carried on the laser disc is separated from the luminance signal and the color signal, and the correlation signal is detected by only the luminance signal to remove noise by removing the noise of the system clock signal. In addition, there is an advantage in that deterioration of image quality can be prevented by removing the perfect noise by freely adjusting the interval of the sample at the time of correlation detection.

Claims (6)

An NTSC / PAL combined noise canceling circuit of a laser disc player system, comprising: first luminance / color separation means for inputting an NTSC composite video signal to separate a luminance signal (Y1) and a color signal (C1), and a PAL composite video signal; Second luminance / color separation means for inputting and separating the luminance signal Y2 and the color signal C2, and control means for discriminating the input state of the NTSC signal or the PAL signal and generating an NTSC / PAL selection control signal; Signal selection means for selectively outputting the luminance signal and the color signal outputted from the first-second luminance / color separation means by the NTSC / PAL selection control signal outputted from the control means, and the luminance selectively outputted from the signal selection means; Pixel correlation detection and coefficient generating means for inputting a signal to detect a correlation between adjacent pixels by the system clock signal and generating a temporary correlation coefficient within a set range; Circuit, characterized in that consists of an adaptive FIR filter means for input to the correlation output from the emitter selection output the luminance signal and the pixel detection and correlation coefficient generation means to remove the noise component by the system clock signal output. The method of claim 1, wherein the first luminance / color separation means comprises: a first band pass filter (32) for inputting an NTSC composite video signal to extract and output a color signal (C1); The first delay unit 34 outputting time delay and the color signal C1 extracted from the first band pass filter 32 from the composite image signal delayed by the first delay unit 34 are added to the luminance signal ( And a first adder (36) for extracting Y1). 3. The method of claim 2, wherein the second luminance / color separation means comprises: a second band pass filter (38) for inputting a PAL composite video signal, extracting and outputting a color signal (C2), and a PAL composite video signal; A luminance signal is obtained by adding the second delay unit 40 outputting a predetermined time delay and the color signal C2 extracted from the second band pass filter 38 from the composite video signal delayed by the second delay unit 40. And a second adder (42) for extracting (Y2). 4. The signal selection means according to claim 3, wherein the signal selecting means inputs the color signal C1 output from the first band pass filter 32 and the color signal C2 output from the second band pass filter 38. A first MUX 44 which selects and outputs one by the NTSC / PAL selection control signal of the controller, a luminance signal Y1 output from the first adder 36, and a color signal output from the second adder 42; And a second MUX (46) for inputting (Y2) to selectively output one by the NTSC / PAL selection control signal of the control unit. 5. The apparatus of claim 4, further comprising: a third delay unit (48) for delaying a predetermined time output of the color signal selected by the first MUX (44), a luminance signal from which noise is removed from the adaptive FIR filter means, and the third And a third adder (54) for adding a delayed output color signal from the delayer (48) to output a composite video signal from which noise is removed. In the NTSC / PAL combined noise canceling circuit of a laser disc player system, a low pass filter 62 for inputting a composite video signal and performing low pass filtering to extract and output a luminance signal, and inputting the composite video signal to delay a predetermined time The fourth delay unit 64 to be output, the composite video signal delayed output from the fourth delay unit 64 and the luminance signal Y3 output from the low pass filter 62 are added to the color signal C3. Extracts and outputs a fourth adder 66 and a luminance signal Y3 outputted from the low pass filter 62 to detect a correlation between adjacent pixels by the system clock signal. A pixel correlation detection and coefficient generation unit 72 for generating coefficients, a luminance signal Y3 output from the low pass filter 62, and a correlation coefficient output from the pixel correlation detection and coefficient generation unit 72 are inputted System An adaptive FIR filter 70 which removes and outputs a noise component to the clock signal, a fifth delayer 68 which delays and outputs the color signal C3 output from the fourth adder 66 for a predetermined time; A fifth adder 74 which adds a luminance signal from which noise is removed from the adaptive FIR filter 70 and a color signal delayed from the fifth delay unit 68 to output a composite image signal from which noise is removed. Circuit, characterized in that the configuration.