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KR930007374B1 - Apparatus and method for controlling detection process of image signal demodulator - Google Patents

Apparatus and method for controlling detection process of image signal demodulator Download PDF

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KR930007374B1
KR930007374B1 KR1019890017412A KR890017412A KR930007374B1 KR 930007374 B1 KR930007374 B1 KR 930007374B1 KR 1019890017412 A KR1019890017412 A KR 1019890017412A KR 890017412 A KR890017412 A KR 890017412A KR 930007374 B1 KR930007374 B1 KR 930007374B1
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signal
color
video signal
detector
output
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KR1019890017412A
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KR910011030A (en
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이용국
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삼성전기 주식회사
서주인
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/646—Circuits for processing colour signals for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N11/00—Colour television systems
    • H04N11/06—Transmission systems characterised by the manner in which the individual colour picture signal components are combined
    • H04N11/12—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only
    • H04N11/14—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only in which one signal, modulated in phase and amplitude, conveys colour information and a second signal conveys brightness information, e.g. NTSC-system
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/647—I.F amplifiers

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Processing Of Color Television Signals (AREA)

Abstract

The invention improves the quality of images by decreasing crosstalks among carriers. The circuit comprises a color signal compression section (10) for sending color carriers-compressed output signal to a detector composed of a signal amplifier and a resonant circuit (C1,L1), a color signal compensating section (20) for compensating compressed color signals. The method has a level changing step, a detecting step and a compensating step for compensating the level difference of changing signals.

Description

영상신호 복조기의 검파제어회로 및 방법Detection Control Circuit and Method of Image Signal Demodulator

제1도는 종래의 영상신호 복조기 검파회로 블럭도.1 is a block diagram of a conventional video signal demodulator detection circuit.

제2도는 본 발명이 적용된 영상신호 복조기의 검파회로 블럭도.2 is a block diagram of a detection circuit of an image signal demodulator to which the present invention is applied.

제3도는 본 발명의 구체적인 실시예를 도시한 상세도.3 is a detailed view showing a specific embodiment of the present invention.

* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings

A1, A2 : 증폭기 D1 : 검파기A1, A2: Amplifier D1: Detector

10 : 색신호억압부 20 : 색신호보상부10: color signal suppression unit 20: color signal compensation unit

본 발명은 영상신호 복조기에 관한 것으로, 특히 영상신호 복조기의 검파회로에서 영상신호와 색신호간의 누화를 줄이는 검파제어회로 및 그 방식에 관한 것이다.The present invention relates to a video signal demodulator, and more particularly, to a detection control circuit and a method for reducing crosstalk between a video signal and a color signal in a detection circuit of a video signal demodulator.

NTSC방송방식에서는 6MHz의 대역폭으로 세개의 반송파(영상반송파, 색부반송파, 음성반송파)를 합성하여 영상신호로 구성하여 전송하게 되는데, 영상신호의 복조시에 음성신호는 주파수대역이 분리되어 중간주파수 여파기에서 충분히 여파되는데 반하여 영상신호와 색신호는 주파수대역이 중첩된 관계로 함께 복조되므로 인하여 서로 누화(Crosstalk)를 일으켜 화질이 열화되는 문제점이 있었다.In the NTSC broadcasting system, three carriers (video carrier, color carrier, and voice carrier) are synthesized and transmitted as a video signal with a bandwidth of 6 MHz. On the other hand, the video signal and the color signal are demodulated together because the frequency bands overlap each other, resulting in crosstalk.

본 발명은 상기한 바와같이 대역폭이 중첩되어 일어나는 누화의 문제점을 개선하기 위하여 안출한 것으로, 영상신호 복조시에 영상반송파와 색부반송파 사이의 레벨차이가 크면 클수록 검파신호와 부반송파 사이의 누화가 적어진다는 점에 착안하여 영상신호의 누화를 줄임으로써 선명한 화상을 제공할 수 있는 영상신호 복조기의 검파제어회로 및 그 방법을 제공하는 것을 특징으로 한다.The present invention has been made to solve the problem of crosstalk caused by overlapping bandwidth, and the larger the level difference between the image carrier and the color subcarrier during demodulation of the video signal, the smaller the crosstalk between the detected signal and the subcarrier. The present invention provides a detection control circuit and a method of a video signal demodulator capable of providing a clear image by reducing crosstalk of a video signal.

상기한 목적을 달성하기 위하여 본 발명에서는 중간주파수 영상신호를 입력으로 하는 전치증폭기와, 전치증폭기의 출력을 검파하여 베이스밴드 영상신호로 출력하는 검파기와, 검파기의 출력단에 출력증폭기를 구비한 NTSC방식 영상신호 복조기의 영상신호 검파회로에 있어서, 전치증폭기의 출력단에 신호증폭단과 공진회로로 구성되어 색부반송파를 억압한 출력신호를 검파기로 인가하는 색신호억압부 ; 상기 검파기의 출력단에 양전원방식의 증폭단과 궤환루프로 구성되어 색신호억압부에서 억압된 색신호량을 보상하는 색신호보상부를 포함하는 것을 특징으로 하는 영상신호 복조기의 검파제어회로를 제공한다.In order to achieve the above object, in the present invention, a preamplifier for inputting an intermediate frequency video signal, a detector for detecting the output of the preamplifier and outputting it as a baseband video signal, and an NTSC method having an output amplifier at the output terminal of the detector A video signal detection circuit of a video signal demodulator, comprising: a color signal suppressor configured to apply an output signal, which is composed of a signal amplifier and a resonant circuit, to an output terminal of a preamplifier and suppresses a color carrier; And a color signal compensator for compensating for the amount of color signals suppressed by the color signal suppressor, which is composed of a positive power amplifier and a feedback loop at an output terminal of the detector.

또한 본 발명은 상기와 같은 목적을 달성하기 위한 방법으로서 입력되는 중간주파수상태의 영상신호인 영상반송파와 색부반송파간의 레벨차이를 발생시키기 위하여 공진현상을 이용하여 상기 반송파신호중 어느 하나만이 레벨을 변환시키는 변환단계 ; 변환단계에서 처리된 신호를 검파하는 단계 ; 검파된 신호중 변환단계에 의하여 변환된 신호를 변환양만큼의 레벨차이를 베이스밴드상태에서 보상하는 보상단계를 포함하여 반송파의 누화를 개선하는 것을 특징으로 하는 영상신호 복조기의 검파제어방법을 제공한다.In addition, the present invention provides a method for achieving the above object by converting the level of only one of the carrier signal using the resonance phenomenon to generate a level difference between the image carrier and the color carrier, which is an image signal of the intermediate frequency state input Transformation stage; Detecting a signal processed in the conversion step; A detection control method of a video signal demodulator is provided by improving a cross-talk of a carrier by including a compensation step of compensating a level difference by a conversion amount in a baseband state among signals detected by a conversion step.

이하 첨부된 도면을 참조하여 본 발명을 상세히 설명한다.Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

제1도는 종래의 영상검파회로를 도시한 것으로서, 검파기(D1)의 입력단에는 중간주파수 영상신호를 입력으로 하는 전치증폭기(A1)가 구성되고 검파기(D1)의 출력단에는 출력증폭기(A2)가 구성된다.FIG. 1 shows a conventional image detector circuit, wherein a preamplifier A1 for inputting an intermediate frequency video signal is configured at an input terminal of a detector D1, and an output amplifier A2 is configured at an output terminal of the detector D1. do.

따라서, 전치증폭기(A1)에 의해 증폭된 중간주파수 영상신호가 검파기(D1)를 통하여 동일한 레벨로 검파되므로 상기한 바와같은 누화의 문제점을 갖게 된다.Therefore, since the intermediate frequency image signal amplified by the preamplifier A1 is detected at the same level through the detector D1, there is a problem of crosstalk as described above.

제2도는 본 발명에 따른 영상검파회로를 블럭으로 도시한 것으로 제1도의 전치증폭기(A1)와 검파기(D1)사이에 영상반송파와 색부반송파의 레벨차이를 발생시키는 수단을 구비하고, 검파기(D1)와 출력증폭기(A2)사이에 검파기(D1)의 입력단에서 발생된 레벨차이를 보상하는 수단을 구비한다.2 is a block diagram of an image detection circuit according to the present invention, and includes means for generating a level difference between an image carrier and a color subcarrier between a preamplifier A1 and a detector D1 of FIG. And a level difference between the output amplifier A2 and the level difference generated at the input of the detector D1.

따라서 레벨차이 발생수단에서는 영상반송파와 색부반송파중의 하나를 억압시키거나 또는 신장시켜 두 신호의 레벨차이를 발생시키고, 공지의 검파기를 통하여 검파한 다음, 레벨차이 보상수단에서 억압되거나 신장된 신호를 다시 보상하여 줌으로써 영상신호의 누화에 의한 신호 대 잡음비를 개선하게 된다.Therefore, the level difference generating means suppresses or extends one of the image carrier and the color carrier so as to generate a level difference between the two signals, detects it through a known detector, and then detects the signal suppressed or extended by the level difference compensation means. By compensating again, the signal-to-noise ratio caused by crosstalk of the image signal is improved.

즉, 중간주파수 상태에서 두 신호의 레벨차이를 발생시킨 다음, 검파기에 의해 복조된 베이스밴드 영상신호 상태에서 두 신호의 레베차이를 다시 보상하는 방식이다.In other words, the level difference between the two signals is generated in the intermediate frequency state, and then the level difference between the two signals is compensated again in the baseband image signal state demodulated by the detector.

이러한 본 발명의 방식을 구현하는 회로는 여러가지의 형태로 구성될 수 있으며, 바람직한 실시예는 제3도에 도시한 바와같다.Circuitry for implementing this manner of the invention may be configured in a variety of forms, the preferred embodiment of which is shown in FIG.

제3도에서는 레벨차이 발생수단으로서 색호를 억압하므로써 레벨차이를 발생시키는 색신호억압부(10)를 검파기(D1)의 출력단에 레벨차이 보상수단으로서 억압된 색신호를 다시 보상해 주는 색신호보상부(20)를 구성하므로써 효과적으로 본 발명의 목적을 달성할 수 있다.In FIG. 3, the color signal compensator 20 which compensates the suppressed color signal as the level difference compensating unit at the output terminal of the detector D1 by the color signal suppressor 10 generating the level difference by suppressing the color arc as the level difference generating means. By configuring), the object of the present invention can be effectively achieved.

제3도를 상세히 살펴보면 색신호억압부(10)는 트랜지스터(Q1)와 저항(R1∼R4) 및 콘덴서(C2)로 이루어진 신호증폭단과 콘덴서(C1) 및 코일(L1)로 이루어진 공진회로로 구성되고, 색신호보상부(20)는 트랜지스터(Q2)와 저항(R5∼R7) 및 콘덴서(C2)로 이루어진 양전원방식의 증폭단과, 콘덴서(C3) 및 저항(R8)으로 이루어진 궤환루프로 구성된다.Referring to FIG. 3, the color signal suppressor 10 includes a signal amplifier stage consisting of a transistor Q1, resistors R1 to R4, and a capacitor C2, and a resonant circuit consisting of a capacitor C1 and a coil L1. The color signal compensator 20 includes a bi-power amplifier stage consisting of a transistor Q2, resistors R5 to R7, and a capacitor C2, and a feedback loop composed of a capacitor C3 and a resistor R8.

따라서, 영상신호 복조시에 음성신호를 억압시킨 중간주파수신호가 색신호억압부(10)로 입력되면 신호증폭단을 거쳐 공진회로에 색부반송파 부분이 억압된다. 즉, 공진회로(L1, C1)의 공진점은 영상반송파주파수(55.25MHz)에 맞추어져 있으므로 측대역에 해당되는 색부반송파가 상대적으로 억압되며, 억압되는 양은 감쇠계수(Damping factor)를 조정할 수 있는 저항(R3)에 의해 조절이 가능하다.Therefore, when the intermediate frequency signal, which suppresses the audio signal at the time of demodulating the video signal, is input to the color signal suppressor 10, the color carrier part is suppressed through the signal amplifier stage to the resonance circuit. That is, since the resonance points of the resonant circuits L1 and C1 are set to the image carrier frequency (55.25 MHz), the color carriers corresponding to the side bands are relatively suppressed, and the amount of suppression is a resistor capable of adjusting the damping factor. Adjustable by (R3).

이와같이 색부반송파 부분이 억압된 영상중간주파수신호를 검파기에서 포락선검파(Envelop Detection)하면 주파수에 따른 평활성(Flatness)을 만족하지 않아 영상베이스밴드에서 차동이득(Differential Gain)특성이 나빠지므로 색신호 보상부(20)에서 궤환루프를 이루는 저항(R8)과 콘덴서(C3)의 조정에 의해 색신호억압부(10)에서 억압된 색신호의 일정량 만큼의 베이스밴드상태에서 다시 보상하여 줌으로써 출력영상신호의 누화를 개선할 수 있다.As such, when the detector detects the image intermediate frequency signal in which the color carrier is suppressed, the color gain compensation is deteriorated in the image baseband because it does not satisfy the flatness according to the frequency. 20) the crosstalk of the output video signal can be improved by compensating again in the baseband state of the predetermined amount of the color signal suppressed by the color signal suppressor 10 by adjusting the resistor R8 and the condenser C3. Can be.

이상과 같은 본 발명에 의하여 반송파간의 누화에 의한 화질열화가 발생할 수 있는 모든 기기에서 반송파간의 누화를 개선하므로써 향상된 화질을 제공할 수 있게 된다.According to the present invention as described above, it is possible to provide improved image quality by improving crosstalk between carriers in all devices in which image quality deterioration may occur due to crosstalk between carriers.

Claims (2)

중간주파수 영상신호를 입력으로 하는 전치증폭기와, 상기 전치증폭기의 출력을 검파하여 베이스밴드 영상신호로 출력하는 검파기와, 상기 검파기의 출력단에 구성된 출력증폭기를 구비한 NTSC방식 영상신호 복조기의 영상신호 검파회로에 있어서, 상기 전치증폭기의 출력단에 신호증폭단과 공진회로(C1, L1)로 구성되어 색부반송파를 억업한 출력신호를 검파기로 인가하는 색신호억압부(10) ; 상기 검파기의 출력단에 양전원방식의 증폭단과 궤환루프(C3, R8)로 구성되어 색신호억압부(10)에서 억압된 색신호량을 보상하는 색신호보상부(20)를 포함하는 것을 특징으로 하는 영상신호 복조기의 검파제어회로.Video signal detection of NTSC type video signal demodulator having a preamplifier that inputs an intermediate frequency video signal, a detector for detecting the output of the preamplifier and outputting it as a baseband video signal, and an output amplifier configured at the output of the detector. A circuit comprising: a color signal suppressing section (10) configured to include a signal amplifying stage and resonant circuits (C1, L1) at an output end of the preamplifier to apply an output signal obtained by suppressing color carriers to a detector; An image signal demodulator comprising a color signal compensator 20 configured to compensate for the amount of color signals suppressed by the color signal suppressor 10 by being composed of a positive power amplifier and feedback loops C3 and R8 at an output terminal of the detector. Detection control circuit. 영상신호 복조기의 영상신호 검파방법에 있어서, 입력되는 중간주파수상태의 영상신호인 영상반송파와 색부반송파간의 레벨차이를 발생시키기 위하여 공진현상을 이용하여 상기 반송파신호중 어느 하나만의 레벨을 변환시키는 단계 ; 상기 변환단계에서 처리된 신호를 검파하는 단계 ; 상기 검파된 신호중 상기 변환단계에 의하여 변환된 신호를 변환양만큼의 레베차이를 베이스밴드상태에서 보상하는 보상단계를 포함하여 반송파의 누화를 개선하는 것을 특징으로 하는 영상신호 복조기의 검파제어방법.A video signal detection method of a video signal demodulator, the method comprising: converting a level of only one of the carrier signals using a resonance phenomenon to generate a level difference between an image carrier and a color carrier, which is an image signal in an intermediate frequency state; Detecting a signal processed in the conversion step; And a compensation step of compensating for the level difference in the baseband state of the signal converted by the converting step among the detected signals, thereby improving crosstalk of the carrier signal.
KR1019890017412A 1989-11-29 1989-11-29 Apparatus and method for controlling detection process of image signal demodulator KR930007374B1 (en)

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