JPS6349434B2 - - Google Patents
Info
- Publication number
- JPS6349434B2 JPS6349434B2 JP57174970A JP17497082A JPS6349434B2 JP S6349434 B2 JPS6349434 B2 JP S6349434B2 JP 57174970 A JP57174970 A JP 57174970A JP 17497082 A JP17497082 A JP 17497082A JP S6349434 B2 JPS6349434 B2 JP S6349434B2
- Authority
- JP
- Japan
- Prior art keywords
- carrier wave
- signal
- modulator
- input
- modulation
- 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.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/76—Television signal recording
- H04N5/91—Television signal processing therefor
- H04N5/92—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Processing Of Color Television Signals (AREA)
- Television Signal Processing For Recording (AREA)
Description
【発明の詳細な説明】
(イ) 技術分野
本発明は、磁気記録再生装置等における変調回
路に係り、特にカラー映像信号の記録再生時、ク
ロマ信号の位相のズレを極減できる同変調回路に
関する。[Detailed Description of the Invention] (a) Technical Field The present invention relates to a modulation circuit in a magnetic recording/reproducing device, etc., and particularly relates to a modulation circuit that can minimize the phase shift of a chroma signal when recording and reproducing a color video signal. .
(ロ) 背景技術
磁気記録再生装置（VTR）、ビデオデイスク及
びテレビゲーム等における映像再生機器では、映
像信号をテレビ受像機の受信帯域に変換する必要
がある。(b) Background Art In video playback devices for magnetic recording and reproducing devices (VTRs), video discs, television games, etc., it is necessary to convert the video signal to the reception band of the television receiver.
そこで第１図の様に搬送波発振器１の出力信号
Vcと映像信号ViをAM変調器２に印加し、該
AM変調器２から変換出力Voを得る構成が多く
使われている。 Therefore, as shown in Figure 1, the output signal of carrier wave oscillator 1 is
Apply Vc and video signal Vi to AM modulator 2 ,
A configuration in which the converted output Vo is obtained from the AM modulator 2 is often used.
ところが変換出力Voのリニアリテイ（直線性
DG）と、輝度変調が施された場合のクロマ信号
の位相のズレDPが問題となる。これらが原信号
に対して悪化すると、輝度信号Ｙは勿論である
が、本来の色が再現できなくなつてしまう。 However, the linearity of the conversion output Vo
DG) and the phase shift DP of the chroma signal when luminance modulation is applied. If these deteriorate compared to the original signal, not only the luminance signal Y but also the original color cannot be reproduced.
従つて前記DG及びDPを小さくすることが変調
回路において重要なポイントとなる。 Therefore, reducing the DG and DP is an important point in the modulation circuit.
一般に変換器は第２図の様な構成になつてお
り、第１の差動対トランジスタ３，４の入力端子
５，６に搬送波信号源７を接続し、共通エミツタ
と電源端子８に接続された第２の差動対トランジ
スタ９，１０の各ベースに接続された変調入力端
子１１，１２に変調入力信号を印加し、出力端子
１３から変換出力を得る。図中１４は定電流源を
示す。 In general, a converter has a configuration as shown in FIG. 2, in which a carrier wave signal source 7 is connected to the input terminals 5 and 6 of the first differential pair transistors 3 and 4, and a carrier wave signal source 7 is connected to the common emitter and the power supply terminal 8. A modulation input signal is applied to modulation input terminals 11 and 12 connected to the respective bases of the second differential pair of transistors 9 and 10, and a converted output is obtained from an output terminal 13. In the figure, 14 indicates a constant current source.
この場合前記変調入力信号は、映像信号を電流
に変換し、前記トランジスタ３，４のスイツチン
グ動作に変調を施している。 In this case, the modulation input signal converts a video signal into a current, and modulates the switching operation of the transistors 3 and 4.
ここで搬送波信号がトランジスタ３，４の各ベ
ースに印加されるときに、トランジスタ９のエミ
ツタ抵抗reは、前記トランジスタ３，４のエミツ
タ電位Veをエミツタ電流即ち前記トランジスタ
９の出力電流Ieからre＝Ve／Ieに依存する。斯
る電流Ieが小さいほど出力即ち端子１３に現われ
る搬送波の時間遅れが大きい特性を第１図の構成
は有することから、搬送波の１点を見た場合、電
流Ieが小さい程、クロマ信号と搬送波の位相ズレ
が大きくなつてしまう。 Here, when a carrier wave signal is applied to each base of the transistors 3 and 4, the emitter resistance re of the transistor 9 changes the emitter potential Ve of the transistors 3 and 4 from the emitter current, that is, the output current Ie of the transistor 9, re= Depends on Ve/Ie. Since the configuration of FIG. 1 has a characteristic that the smaller the current Ie, the greater the time delay of the output, that is, the carrier wave appearing at the terminal 13, when looking at one point of the carrier wave, the smaller the current Ie, the greater the time delay between the chroma signal and the carrier wave. The phase shift will become large.
一方変調電流が大であると、reが小さくなり、
搬送波の位相遅れが小さくなり、搬送波の入出力
位相差のズレは小さくなる。 On the other hand, when the modulation current is large, re becomes small,
The phase delay of the carrier wave becomes smaller, and the shift in the input/output phase difference of the carrier wave becomes smaller.
この模様を第５図を用いて説明すると、入力搬
送波ベクトルViに対し、理想的な出力ベクトル
（入力に対して位相反転される回路即ち180゜位相
が異なる場合）は第５図イに示す如くViとVoが
互に逆向きのベクトルとなる。 To explain this pattern using Figure 5, for the input carrier wave vector Vi, the ideal output vector (in a circuit whose phase is inverted with respect to the input, that is, when the phase is different by 180°) is as shown in Figure 5 A. Vi and Vo become vectors in opposite directions.
ところが前述の位相ズレが生じる場合は、第５
図ロに示す様にキヤリアの位相遅れにより、クロ
マ信号の位相遅れが生じる。 However, if the aforementioned phase shift occurs, the fifth
As shown in Figure 2, a phase delay in the carrier causes a phase delay in the chroma signal.
(ハ) 発明の目的
本発明は従来変調回路で生じていた位相のズレ
を補償することを目的とする。(c) Purpose of the invention The purpose of the present invention is to compensate for the phase shift that has occurred in conventional modulation circuits.
(ニ) 実施例
第３図は本発明の変調回路の一実施例、第４図
同回路の説明波形図、第５図ハは同回路により位
相補正をなしたときのベクトル合成図を示す。(d) Embodiment FIG. 3 shows an embodiment of the modulation circuit of the present invention, FIG. 4 shows an explanatory waveform diagram of the same circuit, and FIG. 5 C shows a vector synthesis diagram when phase correction is performed by the same circuit.
次に本発明の同回路について動作を説明する
と、入力端子１４に第４図に示した階段波状のビ
デオ信号を印加した場合、クロマ信号ａ，ｂ，
ｃ，ｄが各々，，，に示す通り輝度レベ
ルの相違により、クロマ信号の位相がズレようと
する。又搬送波発振器１からの搬送波信号とAM
変調器２からの変換出力との搬送波位相差を見る
と、第４図のの領域ではAM変調器２の電流が
大きく、従つて入出力の位相差は極く小さく第５
図イに示すベクトル図に等しい。ところがから
に従つて変調電流が段々と小さくなつて搬送波
信号がAM変調器２に入力されてから出力端子１
３に現われる迄に時間遅れが生じ、これに伴つて
クロマ信号の位相遅れが現われる。 Next, to explain the operation of the same circuit of the present invention, when the step wave video signal shown in FIG. 4 is applied to the input terminal 14, the chroma signals a, b,
As shown in c and d, respectively, the phase of the chroma signal tends to shift due to the difference in brightness level. Also, the carrier wave signal from carrier wave oscillator 1 and the AM
Looking at the carrier wave phase difference with the converted output from the modulator 2 , the current of the AM modulator 2 is large in the region of FIG.
It is equivalent to the vector diagram shown in Figure A. However, as the modulation current gradually decreases and the carrier signal is input to the AM modulator 2 , the output terminal 1
A time delay occurs until the chroma signal appears at 3, and a phase delay of the chroma signal appears along with this.
そこでAM変調器２の出力側から帰還用コンデ
ンサ１５によつて入力側に交流帰還を施すと、入
力信号としては搬送波発振器１の出力と帰還信号
VFがベクトル的に合成され、合成入力として第
５図ハにおける入力Viに対してVi′となりその合
成入力はベクトル的に原入力信号に対して進むこ
とになり、従つて出力信号が自動的に補正される
ことになる。 Therefore, when AC feedback is applied from the output side of the AM modulator 2 to the input side using the feedback capacitor 15, the input signals are the output of the carrier wave oscillator 1 and the feedback signal.
V F is vectorially synthesized, and the synthesized input becomes Vi' for the input Vi in Figure 5 C, and the synthesized input advances vectorially with respect to the original input signal, so that the output signal automatically changes. will be corrected.
(ホ) 効果
本発明の変調回路によれば、帰還量の最適化に
より、変換出力の搬送波の位相のズレをほぼ除去
することができ、高性能の変調回路を構成でき
る。(e) Effects According to the modulation circuit of the present invention, by optimizing the amount of feedback, it is possible to almost eliminate the phase shift of the carrier wave of the converted output, and a high-performance modulation circuit can be constructed.
第１図は従来の変調回路のブロツク図、第２図
は本発明を説明するための要部回路図、第３図は
本発明の変調回路を示すブロツク図、第４図は本
発明の同回路の説明波形図、第５図イ〜ハは本発
明の同回路を説明するためのベクトル図を示す。
主な図番の説明、１……搬送波発振器、２……
AM変調器、８……電源端子、１４……入力端
子、１５……帰還用コンデンサ。
FIG. 1 is a block diagram of a conventional modulation circuit, FIG. 2 is a main circuit diagram for explaining the present invention, FIG. 3 is a block diagram showing a modulation circuit of the present invention, and FIG. 4 is a block diagram of the same according to the present invention. Waveform diagrams for explaining the circuit, FIGS. 5A to 5C show vector diagrams for explaining the circuit of the present invention. Explanation of main figure numbers, 1 ...carrier wave oscillator, 2 ...
AM modulator, 8...power supply terminal, 14...input terminal, 15...feedback capacitor.
Claims (1)
波がベースに印加され、映像信号がエミツタに印
加される差動型のAM変調器とを備え、前記AM
変調器を構成するトランジスタのエミツタ抵抗に
起因するDP特性を補償するようにした変調回路
であつて、前記AM変調器の変調出力信号を前記
AM変調器を構成するトランジスタのベースに帰
還する為のコンデンサを設けたことを特徴とする
変調回路。1 comprises a carrier wave oscillator and a differential AM modulator in which the carrier wave from the carrier wave oscillator is applied to the base and the video signal is applied to the emitter,
A modulation circuit configured to compensate for DP characteristics caused by emitter resistance of a transistor constituting a modulator, wherein the modulation output signal of the AM modulator is
A modulation circuit characterized by providing a capacitor for feeding back to the base of a transistor that constitutes an AM modulator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57174970A JPS5963893A (en) | 1982-10-04 | 1982-10-04 | Modulating circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57174970A JPS5963893A (en) | 1982-10-04 | 1982-10-04 | Modulating circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5963893A JPS5963893A (en) | 1984-04-11 |
| JPS6349434B2 true JPS6349434B2 (en) | 1988-10-04 |
Family
ID=15987916
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57174970A Granted JPS5963893A (en) | 1982-10-04 | 1982-10-04 | Modulating circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5963893A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7443905B1 (en) * | 2004-03-19 | 2008-10-28 | National Semiconductor Corporation | Apparatus and method for spread spectrum clock generator with accumulator |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5539408A (en) * | 1978-09-13 | 1980-03-19 | Hitachi Ltd | High frequency modulator circuit |
-
1982
- 1982-10-04 JP JP57174970A patent/JPS5963893A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5963893A (en) | 1984-04-11 |
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