JPH06105244A - Video signal fm modulator - Google Patents
Video signal fm modulatorInfo
- Publication number
- JPH06105244A JPH06105244A JP4251485A JP25148592A JPH06105244A JP H06105244 A JPH06105244 A JP H06105244A JP 4251485 A JP4251485 A JP 4251485A JP 25148592 A JP25148592 A JP 25148592A JP H06105244 A JPH06105244 A JP H06105244A
- Authority
- JP
- Japan
- Prior art keywords
- video signal
- frequency
- modulator
- frequency divider
- harmonic
- 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
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は映像信号ＦＭ変復調装置
に係わり、特にＦＭ変調信号を分周する分周器を設けた
映像信号ＦＭ変調装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal FM modulator / demodulator, and more particularly to a video signal FM modulator provided with a frequency divider for dividing an FM modulated signal.
【０００２】[0002]
【従来技術および発明が解決しようとする課題】従来の
映像信号ＦＭ変調装置ＥＱ2は図４に示すように、映像
信号入力端子Ｔ11に接続された自走電圧制御発振器１１
で構成され、映像信号入力端子Ｔ11から入力された映像
信号ｆ1をＦＭ変調し、ＦＭ映像信号ｆ5としてＦＭ映像
信号出力端子Ｔ12から出力する。2. Description of the Related Art A conventional video signal FM modulator EQ 2 has a free-running voltage controlled oscillator 11 connected to a video signal input terminal T 1 1 as shown in FIG.
The video signal f 1 input from the video signal input terminal T 11 is FM-modulated and is output from the FM video signal output terminal T 12 as an FM video signal f 5 .
【０００３】上記構成の映像信号ＦＭ変調装置ＥＱ
2で、図５に示すように、自走電圧制御発振器１１の自
走発振数を６ＭＨｚに設定すると、ＦＭ映像信号ｆ5は
この６ＭＨｚを中心周波数として２ＭＨｚ〜１０ＭＨｚ
の範囲に分布する。映像信号ｆ1はベースバンドで最高
４ＭＨｚの範囲にあるのでＦＭ映像信号ｆ5と映像信号
ｆ1のオーバーラップした部分はノイズとなり、ＦＭ映
像信号ｆ5を復調した際、映像が不鮮明になる難点があ
る。更に、ＦＭ映像信号ｆ5には変調時に発生する１２
ＭＨｚが中心周波数となっている高調波のなかで一番強
い第２高調波ｈｎ4が発生するので第２高調波ｈｎ4及び
更に高次の高調波の影響を受ける等の難点がある。A video signal FM modulator EQ having the above structure
2 , when the free-running oscillation frequency of the free-running voltage controlled oscillator 11 is set to 6 MHz, the FM video signal f 5 has a center frequency of 6 MHz and a frequency of 2 MHz to 10 MHz.
Distributed in the range of. Since the video signal f 1 is in the range of up to 4 MHz in the baseband, the overlapping portion of the FM video signal f 5 and the video signal f 1 becomes noise, and when demodulating the FM video signal f 5 , the image becomes unclear. There is. Further, the FM video signal f 5 is generated at the time of 12
Since the strongest second harmonic hn 4 is generated among the harmonics having the center frequency of MHz, there is a problem that the second harmonic hn 4 and higher harmonics are affected.
【０００４】[0004]
【発明の目的】本発明は上述した難点に鑑みなされたも
ので、変調時に発生する不用な高調波を減衰し、復調時
に鮮明な映像が得られる映像信号ＦＭ変復調装置を提供
することを目的とする。SUMMARY OF THE INVENTION It is an object of the present invention to provide a video signal FM modulator / demodulator capable of attenuating unnecessary harmonics generated during modulation and obtaining a clear image during demodulation. To do.
【０００５】[0005]
【課題を解決するための手段】本発明による映像信号Ｆ
Ｍ変調装置は入力された映像信号をＦＭ変調する自走電
圧制御発振器と、自走電圧制御発振器から出力されるＦ
Ｍ変調信号の中心周波数を分周する分周器と、分周器で
分周された中心周波数でＦＭ変調されたＦＭ映像信号の
低域を通過させるローパスフィルタとを備えている。A video signal F according to the present invention
The M modulator is a free-running voltage-controlled oscillator that FM-modulates an input video signal, and an F-frequency output from the free-running voltage-controlled oscillator.
A frequency divider that divides the center frequency of the M-modulated signal and a low-pass filter that passes the low frequency band of the FM video signal that has been FM-modulated at the center frequency divided by the frequency divider are provided.
【０００６】[0006]
【作用】自走電圧制御発振器で入力された映像信号をＦ
Ｍ変調し、出力側からＦＭ映像信号として出力する。こ
のＦＭ映像信号の中心周波数を分周器で分周すると、出
力はデューティー５０％の矩形波となる。この矩形波を
中心周波数とするＦＭ映像信号の低域をローパスフィル
タで通過させる。Operation: The video signal input by the free-running voltage controlled oscillator is F
M-modulate and output as an FM video signal from the output side. When the center frequency of this FM video signal is divided by a frequency divider, the output becomes a rectangular wave with a duty of 50%. The low-pass filter passes the low frequency band of the FM video signal having the rectangular wave as the center frequency.
【０００７】[0007]
【実施例】以下、本発明による映像信号ＦＭ変調装置Ｅ
Ｑ1の一実施例を図１〜図３に従って詳述する。本発明
による映像信号ＦＭ変調装置ＥＱ1は図１に示すよう
に、自走周波数が１２ＭＨｚの自走電圧制御発振器１、
デューティー５０％のフリップフロップからなる１／２
分周器２、ローパスフィルタ３で構成され、自走電圧制
御発振器１の入力側は映像信号入力端子Ｔ1に接続さ
れ、出力側は１／２分周器２を介してローパスフィルタ
３に接続されている。また、ローパスフィルタ３の出力
側はＦＭ映像信号出力端子Ｔ2と接続されている。DESCRIPTION OF THE PREFERRED EMBODIMENTS Video signal FM modulator E according to the present invention
An example of Q 1 will be described in detail with reference to FIGS. As shown in FIG. 1, a video signal FM modulator EQ 1 according to the present invention has a free-running voltage-controlled oscillator 1 having a free-running frequency of 12 MHz,
1/2 consisting of flip-flops with 50% duty
It is composed of a frequency divider 2 and a low-pass filter 3. The input side of the free-running voltage controlled oscillator 1 is connected to the video signal input terminal T 1 , and the output side is connected to the low-pass filter 3 via the 1/2 frequency divider 2. Has been done. The output side of the low pass filter 3 is connected to the FM video signal output terminal T 2 .
【０００８】上記構成の映像信号ＦＭ変調装置ＥＱ1の
映像信号入力端子Ｔ1から映像信号ｆ1が入力されると、
図２に示すように１／２分周器入力ＦＭ変調信号ｆ2は
１２ＭＨｚを中心周波数として８ＭＨｚ〜１６ＭＨｚの
範囲に分布する。この、変調時に発生する高調波のなか
で一番強い第２高調波ｈｎ1は２４ＭＨｚが中心周波数
となっているので１６ＭＨｚ〜３２ＭＨｚの範囲に分布
する。１／２分周器２の出力側から出力される１／２分
周器出力ＦＭ変調信号ｆ3には、１２ＭＨｚが中心周波
数となつている第２高調波ｈｎ2と、１８ＭＨｚが中心
周波数となつている第３高調波ｈｎ3が含まれれるが、
第２高調波ｈｎ2成分は１／２分周器２で分周する際、
デューティーがほぼ５０％となるようにしたため極めて
小さく、第２高調波ｈｎ2の側波帯による影響は軽減さ
れる。また、第３次以上の高調波は１０ＭＨｚ以下の周
波数だけを通過させるローパスフィルタ３で減衰され
る。このため、ＦＭ映像信号出力端子Ｔ2から出力され
るＦＭ映像信号ｆ4は中心周波数が６ＭＨｚで高調波の
側波帯による影響は軽減されている。When the video signal f1 is input from the video signal input terminal T 1 of the video signal FM modulator EQ 1 having the above structure,
As shown in FIG. 2, the ½ frequency divider input FM modulation signal f 2 is distributed in the range of 8 MHz to 16 MHz with the center frequency of 12 MHz. The second harmonic hn 1, which is the strongest of the harmonics generated during modulation, has a center frequency of 24 MHz, and therefore is distributed in the range of 16 MHz to 32 MHz. The 1/2 frequency divider output FM modulation signal f 3 output from the output side of the 1/2 frequency divider 2 has the second harmonic wave hn 2 having a center frequency of 12 MHz and the center frequency of 18 MHz. The third harmonic hn 3 is included,
When the second harmonic hn 2 component is divided by the 1/2 divider 2,
Since the duty is set to about 50%, it is extremely small, and the influence of the sideband of the second harmonic wave hn 2 is reduced. Further, the third and higher harmonics are attenuated by the low pass filter 3 which passes only frequencies of 10 MHz or less. Therefore, the FM video signal f 4 output from the FM video signal output terminal T 2 has a center frequency of 6 MHz and the influence of sidebands of higher harmonics is reduced.
【０００９】[0009]
【発明の効果】本発明による映像信号ＦＭ変調装置は入
力された映像信号をＦＭ変調する自走電圧制御発振器
と、自走電圧制御発振器から出力されるＦＭ変調信号の
中心周波数を分周する分周器と、分周器で分周された中
心周波数でＦＭ変調されたＦＭ映像信号の低域を通過さ
せるローパスフィルタとを備えていので、変調時に発生
する不用な高調波の妨害を除去し、復調時に鮮明な映像
が得られる。The video signal FM modulator according to the present invention divides the center frequency of the free-running voltage control oscillator for FM-modulating the input video signal and the FM modulation signal output from the free-running voltage control oscillator. Since it has a frequency divider and a low-pass filter that passes the low frequency band of the FM video signal FM-modulated at the center frequency divided by the frequency divider, unnecessary harmonic interference generated during modulation is removed, A clear image can be obtained during demodulation.
【図１】本発明によ映像信号ＦＭ変調装置の一実施例を
示すブロック図。FIG. 1 is a block diagram showing an embodiment of a video signal FM modulator according to the present invention.
【図２】本発明によ映像信号ＦＭ変調装置の特性図。FIG. 2 is a characteristic diagram of a video signal FM modulator according to the present invention.
【図３】本発明によ映像信号ＦＭ変調装置の特性図。FIG. 3 is a characteristic diagram of a video signal FM modulator according to the present invention.
【図４】従来の映像信号ＦＭ変調装置のブロック図。FIG. 4 is a block diagram of a conventional video signal FM modulator.
【図５】従来の映像信号ＦＭ変調装置の特性図。FIG. 5 is a characteristic diagram of a conventional video signal FM modulator.
１・・・・・・自走電圧制御発振器 ２・・・・・・１／２分周器（分周器） ３・・・・・・ローパスフィルタ 1 ・ ・ Free-running voltage controlled oscillator 2 ・ ・ 1/2 divider (divider) 3 ・ ・ ・ ・ Low-pass filter
Claims (1)
圧制御発振器と、前記自走電圧制御発振器から出力され
るＦＭ変調信号の中心周波数を分周する分周器と、前記
分周器で分周された中心周波数でＦＭ変調されたＦＭ映
像信号の低域を通過させるローパスフィルタとを備えた
ことを特徴とする映像信号ＦＭ変調装置。1. A free-running voltage-controlled oscillator for FM-modulating an input video signal, a frequency divider for dividing the center frequency of an FM-modulated signal output from the free-running voltage-controlled oscillator, and the frequency divider. And a low-pass filter that passes a low frequency band of an FM video signal FM-modulated at the center frequency divided by.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4251485A JPH06105244A (en) | 1992-09-21 | 1992-09-21 | Video signal fm modulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4251485A JPH06105244A (en) | 1992-09-21 | 1992-09-21 | Video signal fm modulator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06105244A true JPH06105244A (en) | 1994-04-15 |
Family
ID=17223510
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4251485A Pending JPH06105244A (en) | 1992-09-21 | 1992-09-21 | Video signal fm modulator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06105244A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006221765A (en) * | 2005-02-14 | 2006-08-24 | Pioneer Electronic Corp | Information recording and reproducing apparatus, and information reproducing method |
-
1992
- 1992-09-21 JP JP4251485A patent/JPH06105244A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006221765A (en) * | 2005-02-14 | 2006-08-24 | Pioneer Electronic Corp | Information recording and reproducing apparatus, and information reproducing method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20010417 |