JPH0370205A - Local oscillation frequency control circuit - Google Patents
Local oscillation frequency control circuitInfo
- Publication number
- JPH0370205A JPH0370205A JP20468189A JP20468189A JPH0370205A JP H0370205 A JPH0370205 A JP H0370205A JP 20468189 A JP20468189 A JP 20468189A JP 20468189 A JP20468189 A JP 20468189A JP H0370205 A JPH0370205 A JP H0370205A
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- signal
- tuner
- difference
- frequency characteristic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000010355 oscillation Effects 0.000 title claims abstract description 14
- 238000001514 detection method Methods 0.000 abstract description 5
- 238000000605 extraction Methods 0.000 abstract description 5
- 230000006866 deterioration Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 235000013351 cheese Nutrition 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、テレビジ璽ン受信機にかいて、チューナ内の
局部発振器の局部発振周波数を制御する局部発振周波数
制御回路に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a local oscillation frequency control circuit for controlling the local oscillation frequency of a local oscillator in a tuner in a television receiver.
従来は、フォスターシーレー回路又ハ、レシオ検波回路
の周波数弁別特性を利用して（特公昭５８−１４０９０
号公報、特公昭５８−１４０８９号公報）、規定中間周
波数とチューナ出力中間周波数の差を検出し、チューナ
内の局部発振器の局部発振周波数を所定の周波数に合わ
せていた。Conventionally, the frequency discrimination characteristics of the Foster-Seeley circuit or ratio detection circuit were utilized (Japanese Patent Publication No. 58-14090).
(Japanese Patent Publication No. 58-14089), the difference between the specified intermediate frequency and the tuner output intermediate frequency was detected, and the local oscillation frequency of the local oscillator in the tuner was adjusted to a predetermined frequency.
上記した従来技術にかいては、周波数弁別特性を利用し
て、テエーナ内の局部発振器の局部発振周波数を所定の
周波数に合わせていたので、チューナに起因するチャン
ネル間周波数特性偏差及びアンテナ端で発生する定在波
による周波数特性劣化が生じると言う問題があった。In the above-mentioned conventional technology, the local oscillation frequency of the local oscillator in the antenna was adjusted to a predetermined frequency using frequency discrimination characteristics, so deviations in frequency characteristics between channels caused by the tuner and generated at the antenna end There was a problem in that frequency characteristics deteriorated due to standing waves.
本発明の目的は、上記した従来技術の問題点を解決し、
チューナに起因するチャンネル間周波数特性偏差及び、
アンテナ端で発生する定在波による周波数特性劣化の軽
減が可能な局部発振周波数制御回路を提供することにあ
る。The purpose of the present invention is to solve the problems of the prior art described above,
Frequency characteristic deviation between channels caused by tuner and
An object of the present invention is to provide a local oscillation frequency control circuit that can reduce deterioration of frequency characteristics due to standing waves generated at an antenna end.
上記目的を達成する為に、テレビジ曹ン受信機の復調映
像信号中のブランキング期間に存在する基準信号の周波
数特性に着目し、その信号の低域成分のみ抜き取り検波
した検波電圧とその信号の高域成分のみ抜き取υ検波し
た検波電圧との差が。In order to achieve the above objective, we focused on the frequency characteristics of the reference signal that exists during the blanking period in the demodulated video signal of the television receiver, and we focused on the detection voltage and the detection voltage obtained by sampling and detecting only the low-frequency components of the signal. The difference between the detected voltage and the detected voltage obtained by extracting only the high frequency component and detecting υ.
基準信号の周波数特性が所定の周波数特性になるときの
検波電圧の差に対して大きいか、小さいかを比較し、そ
の比較によシ得られる差分がゼロになる様に、チューナ
内の局部発振器の制御端子に制御電圧を加える。The local oscillator in the tuner is compared to see if it is larger or smaller than the difference in detection voltage when the frequency characteristics of the reference signal becomes the predetermined frequency characteristics, and the difference obtained by the comparison is zero. Apply a control voltage to the control terminal of
本発明は、テレビジ璽ン受信機の復調映像信号中のブラ
ンキング期間に存在する基準信号の周波数特性を検知す
る事で、チューナ内の局部発振器の局部発振周波数を制
御する為、チ具−すに起因するチャンネル間周波数偏差
及び、アンテナ端で発生する定在波による周波数特性劣
化を軽減することができる。The present invention uses a tool to control the local oscillation frequency of a local oscillator in a tuner by detecting the frequency characteristics of a reference signal that exists during a blanking period in a demodulated video signal of a television receiver. It is possible to reduce inter-channel frequency deviation caused by this and deterioration of frequency characteristics due to standing waves generated at the antenna end.
以下本発明の一実施例を図を用い説明する。 An embodiment of the present invention will be described below with reference to the drawings.
図は本発明の一実施例を示すブロック図である。The figure is a block diagram showing one embodiment of the present invention.
図にかいて、１はチューナ、２は映像信号を復調する映
像復調回路、３は映像復調回路２より出力される復調映
像信号、４は復調映像信号５のブランキング期間に存在
する基準信号を抽出する波形抽出回路、である。波形抽
出回路４によって抽出された基準信号は、その信号の低
い周波数成分を選択する低域用バンドパスフィルタ５、
高い周波数成分を選択する高域用バンドパスフィルタ６
を各々通過した後、検波器９ 、１０にで検波され直流
電圧に変換される。そして、この検波電圧の差１１を、
比較器７において、基準電圧１２（復調映像信号３０周
波数特性が所定の周波数特性となる時における検波電圧
の差１１の値）と比較し、その差分を制御電圧として局
部発振器制御信号８に加える事により１チユーナ１内の
局部発振器の局部発振周波数を制御し、復調映像信号３
の周波数特性を一定に保持し、安定な画面を提供するも
のである。In the figure, 1 is a tuner, 2 is a video demodulation circuit that demodulates the video signal, 3 is a demodulated video signal output from the video demodulation circuit 2, and 4 is a reference signal that exists during the blanking period of the demodulated video signal 5. This is a waveform extraction circuit for extraction. The reference signal extracted by the waveform extraction circuit 4 is passed through a low-pass bandpass filter 5 that selects the low frequency components of the signal;
High frequency band pass filter 6 that selects high frequency components
After passing through each of them, the waves are detected by detectors 9 and 10 and converted into a DC voltage. Then, the difference 11 of this detected voltage is
The comparator 7 compares it with a reference voltage 12 (the value of the detected voltage difference 11 when the demodulated video signal 30 frequency characteristic becomes a predetermined frequency characteristic), and adds the difference to the local oscillator control signal 8 as a control voltage. The local oscillation frequency of the local oscillator in one tuner 1 is controlled by the demodulated video signal 3.
It maintains the frequency characteristics constant and provides a stable screen.
本発明によれば、復調映像信号の周波数特性を判別する
事によ）、チューナ内の局部発振器の局部発振周波数を
制御している為、チューナに起因する、上記信号のチャ
ンネル間の周波数特性偏差を軽減する事ができる。會た
、さらにアンテナ端で発生する定在波による周波数特性
の劣化を軽減する事ができる。According to the present invention, since the local oscillation frequency of the local oscillator in the tuner is controlled by determining the frequency characteristics of the demodulated video signal, the frequency characteristic deviation between the channels of the signal caused by the tuner is can be reduced. Furthermore, deterioration of frequency characteristics due to standing waves generated at the antenna end can be reduced.
図は本発明の一実施例としての局部発振周波数制御回路
を示すブロック図である。
１・・・・・・・・・チー−す、２・・・・・・・・・
映像復調回路、４・・・・・・・・・波形抽出回路、５
，６・・・・・・・・・バンドパスフィルタ、７・・・
・・・・・・比較器、９．１０・・・・・・・・・検波
器。The figure is a block diagram showing a local oscillation frequency control circuit as an embodiment of the present invention. １・・・・・・・・・Cheese、２・・・・・・・・・
Video demodulation circuit, 4... Waveform extraction circuit, 5
, 6...Band pass filter, 7...
...Comparator, 9.10 ......Detector.
Claims (1)
の局部発振出力により周波数変換して出力するチューナ
と、該チューナより出力された信号を復調して、復調映
像信号を得る映像復調回路と、を具備したテレビジヨン
受信機において、 前記復調映像信号中のブランキング期間に存在する基準
信号を抽出する第１の手段と、抽出された前記基準信号
の低域成分のみを抜き取り検波して出力する第２の手段
と、抽出された前記基準信号の高域成分のみを抜き取り
検波して出力する第３の手段と、前記第２の手段からの
検波出力と前記第３の手段からの検波出力との差を導く
第４の手段と、該第４の手段より導かれた前記検波出力
の差と基準値とを比較して出力する第５の手段と、から
成り、該第５の手段による比較出力を、前記チューナ内
の局部発振器の局部発振周波数を制御する信号に加える
ことにより、前記復調映像信号の周波数特性を所定の周
波数特性に設定することを特徴とする局部発振周波数制
御回路。[Claims] 1. A tuner that converts the frequency of a selected signal using a local oscillation output from a built-in local oscillator and outputs the frequency-converted signal; and a tuner that demodulates the signal output from the tuner to generate a demodulated image. a video demodulation circuit for obtaining a signal; a first means for extracting a reference signal present in a blanking period in the demodulated video signal; and a low frequency component of the extracted reference signal. a second means for selectively detecting and outputting only the extracted high frequency components of the reference signal; a third means for selectively detecting and outputting only the high frequency components of the extracted reference signal; a fourth means for deriving the difference between the detected output from the third means; and a fifth means for comparing and outputting the difference between the detected output derived from the fourth means and a reference value. , the frequency characteristic of the demodulated video signal is set to a predetermined frequency characteristic by adding the comparison output by the fifth means to a signal that controls the local oscillation frequency of a local oscillator in the tuner. Local oscillation frequency control circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20468189A JPH0370205A (en) | 1989-08-09 | 1989-08-09 | Local oscillation frequency control circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20468189A JPH0370205A (en) | 1989-08-09 | 1989-08-09 | Local oscillation frequency control circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0370205A true JPH0370205A (en) | 1991-03-26 |
Family
ID=16494543
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20468189A Pending JPH0370205A (en) | 1989-08-09 | 1989-08-09 | Local oscillation frequency control circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0370205A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0583312A (en) * | 1991-09-20 | 1993-04-02 | Kokusai Electric Co Ltd | Receiver for digital phase modulation signal |
| JP2007141277A (en) * | 2005-11-14 | 2007-06-07 | Sony Corp | Optical disk recording medium, disk manufacturing method and recorder |
-
1989
- 1989-08-09 JP JP20468189A patent/JPH0370205A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0583312A (en) * | 1991-09-20 | 1993-04-02 | Kokusai Electric Co Ltd | Receiver for digital phase modulation signal |
| JP2007141277A (en) * | 2005-11-14 | 2007-06-07 | Sony Corp | Optical disk recording medium, disk manufacturing method and recorder |
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