JPH06233157A - Received tv signal processing circuit for catv - Google Patents
Received tv signal processing circuit for catvInfo
- Publication number
- JPH06233157A JPH06233157A JP5039273A JP3927393A JPH06233157A JP H06233157 A JPH06233157 A JP H06233157A JP 5039273 A JP5039273 A JP 5039273A JP 3927393 A JP3927393 A JP 3927393A JP H06233157 A JPH06233157 A JP H06233157A
- Authority
- JP
- Japan
- Prior art keywords
- signal
- circuit
- frequency
- component
- received
- 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.)
- Granted
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はＣＡＴＶ用受信ＴＶ信号
処理回路に係り、特にＣＡＴＶ装置におけるＴＶ同一チ
ャンネル再送信回路のキャリア発生手段の改良に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving TV signal processing circuit for CATV, and more particularly to improvement of carrier generating means of a TV co-channel retransmitting circuit in a CATV device.
【０００２】[0002]
【従来の技術】地上の電波を使ってテレビ放送をする
と、高層ビル等で電波が反射し、受信画面が二重にな
る、いわゆる、ゴースト障害が起こる。この対策として
放送局側でゴーストを除去するための基準信号（Ghost
Cancel Reference，ＧＣＲ信号）を映像信号に重畳し、
受信側でこのＧＣＲ信号を検出して、これによりゴース
ト成分を除去する装置が、例えば、特開平４−１０７７
６号等に提案されている。2. Description of the Related Art When terrestrial radio waves are used for television broadcasting, radio waves are reflected by skyscrapers and the like, resulting in double reception screens, so-called ghost interference. As a countermeasure, the reference signal (Ghost
Cancel Reference, GCR signal) is superimposed on the video signal,
An apparatus that detects this GCR signal on the receiving side and removes the ghost component by this is disclosed in, for example, Japanese Patent Laid-Open No. 1077/1992
Proposed in No. 6 etc.
【０００３】而してＣＡＴＶ装置においてかかるＧＣＲ
信号を含む映像信号を受信する場合、ゴースト除去のた
めに図２又は図３に示す構成の受信映像信号処理回路が
各チャンネル毎に用いられていた。Thus, such a GCR in a CATV device
When receiving a video signal including a signal, a reception video signal processing circuit having the configuration shown in FIG. 2 or 3 is used for each channel for removing a ghost.
【０００４】図２において、１はダウンコンバータ、２
は局部発振器、３はＩＦ増幅器、４は検波回路、５は変
調器、６はアップコンバータ、７はＰＬＬ回路、８はＶ
ＣＯ（電圧制御発振器）、９はゴースト除去回路であ
る。入力端子ＩＮに印加された受信ＴＶ信号はダウンコ
ンバータ１によりその周波数をダウンさせて所定の周波
数のＩＦ信号に変換され、このＩＦ信号をＩＦ増幅器３
で増幅してから検波回路４で検波して得られた映像信号
をゴースト除去回路９に与えて、前記ＧＣＲ信号により
ゴースト成分を除去する。In FIG. 2, 1 is a down converter, 2
Is a local oscillator, 3 is an IF amplifier, 4 is a detection circuit, 5 is a modulator, 6 is an up converter, 7 is a PLL circuit, and 8 is V.
CO (voltage controlled oscillator), 9 is a ghost elimination circuit. The received TV signal applied to the input terminal IN is downconverted in frequency by the downconverter 1 to be converted into an IF signal of a predetermined frequency, and this IF signal is converted into an IF amplifier 3
The video signal obtained by being detected by the detection circuit 4 after being amplified by is given to the ghost removal circuit 9, and the ghost component is removed by the GCR signal.
【０００５】ゴースト成分を除去した映像信号は変調器
５によって再度変調し、その変調出力はアップコンバー
タ６によりその周波数をアップさせて前記受信ＴＶ信号
と同一周波数のＴＶ信号に変換し、出力端子ＯＵＴに出
力される。図３の回路において、１０はＶＣＯ８を内蔵
する完全同期検波回路で、図３の回路の動作は図２の回
路とほぼ同様である。The video signal from which the ghost component has been removed is re-modulated by the modulator 5, and the modulated output is converted into a TV signal having the same frequency as the received TV signal by increasing the frequency thereof by the up converter 6 and the output terminal OUT. Is output to. In the circuit of FIG. 3, reference numeral 10 is a perfect synchronous detection circuit incorporating a VCO 8, and the operation of the circuit of FIG. 3 is almost the same as that of the circuit of FIG.
【０００６】[0006]
【発明が解決しようとする課題】さて、図２又は図３の
回路においては局部発振器２の出力周波数信号がダウン
コンバータ１及びアップコンバータ６に供給され前記の
周波数変換を行っており、その場合、前記ＩＦ信号の周
波数ｆ1と変調出力の周波数ｆ2は同一であると仮定して
いる。In the circuit of FIG. 2 or 3, the output frequency signal of the local oscillator 2 is supplied to the down converter 1 and the up converter 6 to perform the above frequency conversion. In that case, It is assumed that the frequency f 1 of the IF signal and the frequency f 2 of the modulation output are the same.
【０００７】しかし通常このままではこの仮定は成立せ
ず同一チャンネルビートが必ず発生するため、図２の回
路ではＰＬＬ回路７により、変調器５にキャリアを供給
するＶＣＯ８に位相ロックをかけ前記ｆ1とｆ2が全く同
一周波数になるようにしている。図３の回路では完全同
期検波回路１０を使用することにより同様の効果を得て
いる。However, this assumption is not normally satisfied as it is, and the same channel beat is always generated. Therefore, in the circuit of FIG. 2, the VCO 8 for supplying the carrier to the modulator 5 is phase-locked by the PLL circuit 7 and f 1 The frequencies f 2 are set to be exactly the same. In the circuit of FIG. 3, the same effect is obtained by using the perfect synchronous detection circuit 10.
【０００８】このように図２及び図３の従来の回路では
同一チャンネルビートの発生を防止するため上述した同
期ロックと呼ばれる方式をとる必要がある。そのため、
ＰＬＬ回路、ＶＣＯ等を用いなければならないので、回
路構成が複雑で高価となる問題がある。またＶＣＯを用
いると、残留ＦＭ分自励のため、Ｃ／Ｎの劣化等が生じ
画質に悪影響を与えるという問題もある。As described above, in the conventional circuits shown in FIGS. 2 and 3, it is necessary to adopt the above-mentioned system called the synchronization lock in order to prevent the occurrence of the same channel beat. for that reason,
Since a PLL circuit, VCO, etc. must be used, there is a problem that the circuit configuration is complicated and the cost is high. Further, when the VCO is used, there is a problem that the self-excitation of the residual FM causes deterioration of C / N and the like, which adversely affects the image quality.
【０００９】従って本発明の目的は同期ロック方式をと
ることなくこれと同一の効果が得られて、しかも回路構
成を簡単かつ安価となし得るＣＡＴＶ用受信ＴＶ信号処
理回路を提供することにある。Therefore, an object of the present invention is to provide a receiving TV signal processing circuit for CATV which can obtain the same effect as the above without using the synchronous lock system and can have a simple and inexpensive circuit structure.
【００１０】[0010]
【課題を解決するための手段】上記目的を達成するた
め、本発明は、ＧＣＲ信号が重畳されている受信ＴＶ信
号をダウンコンバータにより所定のＩＦ信号に変換し、
該ＩＦ信号を検波して得られた映像信号を前記ＧＣＲ信
号で処理することによりゴースト成分を除去すると共に
再度変調器により変調してその変調出力をアップコンバ
ータにより前記受信ＴＶ信号と同一周波数のＴＶ信号に
変換して出力するＣＡＴＶ用受信ＴＶ信号処理回路にお
いて、前記ＩＦ信号を分周する分周手段と、該分周手段
の分周出力から前記ＩＦ信号と同一周波数の信号成分を
抽出するフィルタ手段とを、備え、該フィルタ手段の上
記信号成分を前記変調器にキャリア信号として供給する
ことを要旨とする。In order to achieve the above object, the present invention converts a received TV signal on which a GCR signal is superimposed into a predetermined IF signal by a down converter,
A video signal obtained by detecting the IF signal is processed by the GCR signal to remove a ghost component and modulated again by a modulator, and the modulation output is upconverted by an up converter to a TV having the same frequency as the received TV signal. In a CATV reception TV signal processing circuit for converting and outputting a signal, a frequency dividing means for dividing the IF signal and a filter for extracting a signal component of the same frequency as the IF signal from a frequency division output of the frequency dividing means. And a means for supplying the signal component of the filter means to the modulator as a carrier signal.
【００１１】[0011]
【作用】ＩＦ信号の分周出力から該ＩＦ信号と同一周波
数の信号成分がキャリアとして変調器に与えられる。従
ってＩＦ信号の周波数と変調出力の周波数は全く同一に
保持されるので、同一チャンネルビートの発生は防止さ
れ、回路構成も簡単になる。From the frequency-divided output of the IF signal, a signal component having the same frequency as the IF signal is given to the modulator as a carrier. Therefore, the frequency of the IF signal and the frequency of the modulated output are kept exactly the same, the occurrence of the same channel beat is prevented, and the circuit configuration is simplified.
【００１２】[0012]
【実施例】以下図面を参照して本発明の実施例を説明す
る。図１は本発明の一実施例として、ＣＡＴＶ装置に設
けられる１チャンネル分の受信ＴＶ信号処理回路を示
す。同図において、図２と同一符号は同一又は類似の回
路をあらわし、特に図２の回路と異なる構成は前記ＰＬ
Ｌ回路及びＶＣＯに代えて、高周波分周器１１及びＩＦ
用ＢＰＦ（バンドパスフィルタ）１２を用いた点にあ
る。なお１３は分岐回路である。分岐回路１４で分岐さ
れたＩＦ信号は高周波分周器１１に加えられる。高周波
分周器１１は適当な入力レベルを有する信号であれば、
その信号が変調波であっても分周し、その分周出力とし
て方形波信号を得る。この方形波信号には無限の高周波
成分が含まれているので、当然元のＩＦ信号と同一周波
数の信号成分も含まれている。従って、ＢＰＦ１２によ
り上記方形波信号から上記信号成分を抽出し、これをキ
ャリアとして変調器５に供給する。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a receiving TV signal processing circuit for one channel provided in a CATV device as an embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 2 represent the same or similar circuits, and the configuration different from the circuit in FIG.
Instead of the L circuit and the VCO, the high frequency divider 11 and the IF
A BPF (bandpass filter) 12 for use is used. Reference numeral 13 is a branch circuit. The IF signal branched by the branch circuit 14 is added to the high frequency divider 11. If the high frequency divider 11 is a signal having an appropriate input level,
Even if the signal is a modulated wave, it is divided and a square wave signal is obtained as the divided output. Since this square wave signal contains infinite high frequency components, naturally, it also contains signal components having the same frequency as the original IF signal. Therefore, the BPF 12 extracts the signal component from the square wave signal and supplies it to the modulator 5 as a carrier.
【００１３】なお、本実施例において、ＩＦ信号から映
像信号を検波しゴースト成分を除去してから変調し再度
ＴＶ信号に変換する動作は前述した従来の回路と同様で
ある。In the present embodiment, the operation of detecting the video signal from the IF signal, removing the ghost component, modulating it, and converting it again into a TV signal is the same as in the conventional circuit described above.
【００１４】本実施例の回路構成ではＩＦ信号を分周し
て得られた方形波信号からＩＦ信号と同一周波数の信号
成分を抽出し、変調器のキャリアとして利用しているの
で、従来のような同期ロック方式をとらなくても同一チ
ャンネルビートの発生を防止することができる。In the circuit configuration of this embodiment, a signal component having the same frequency as the IF signal is extracted from the square wave signal obtained by dividing the IF signal and used as the carrier of the modulator. It is possible to prevent the occurrence of co-channel beats without using a simple synchronization lock method.
【００１５】[0015]
【発明の効果】以上説明したように本発明によれば、従
来の同期ロック方式をとらないので、ＶＣＯ等の回路は
不要となり、回路構成が簡単かつ安価になる。またＶＣ
Ｏを用いないので、残留ＦＭ分はＩＦ変換用局部発振器
による残留ＦＭ分だけとなり、画像への悪影響も軽減さ
れる。As described above, according to the present invention, since the conventional synchronous lock system is not adopted, a circuit such as a VCO is not necessary, and the circuit configuration is simple and inexpensive. Also VC
Since O is not used, the residual FM component is only the residual FM component by the IF conversion local oscillator, and the adverse effect on the image is reduced.
【図１】本発明の一実施例を示すブロック図である。FIG. 1 is a block diagram showing an embodiment of the present invention.
【図２】従来のＣＡＴＶ用受信ＴＶ信号処理回路の一例
を示すブロック図である。FIG. 2 is a block diagram showing an example of a conventional received TV signal processing circuit for CATV.
【図３】従来のＣＡＴＶ用受信ＴＶ信号処理回路の他の
例を示すブロック図である。FIG. 3 is a block diagram showing another example of a conventional receiving TV signal processing circuit for CATV.
１ ダウンコンバータ ２ 局部発振器 ４ 検波回路 ５ 変調器 ６ アップコンバータ ９ ゴースト除去回路 １１ 高周波分周器 １２ ＢＰＦ 1 Down Converter 2 Local Oscillator 4 Detection Circuit 5 Modulator 6 Up Converter 9 Ghost Removal Circuit 11 High Frequency Divider 12 BPF
Claims (1)
号をダウンコンバータにより所定のＩＦ信号に変換し、
該ＩＦ信号を検波して得られた映像信号を前記ＧＣＲ信
号で処理することによりゴースト成分を除去すると共に
再度変調器により変調してその変調出力をアップコンバ
ータにより前記受信ＴＶ信号と同一周波数のＴＶ信号に
変換して出力するＣＡＴＶ用受信ＴＶ信号処理回路にお
いて、前記ＩＦ信号を分周する分周手段と、該分周手段
の分周出力から前記ＩＦ信号と同一周波数の信号成分を
抽出するフィルタ手段とを、備え、該フィルタ手段の上
記信号成分を前記変調器にキャリア信号として供給する
ことを特徴とするＣＡＴＶ用受信ＴＶ信号処理回路。1. A received TV signal on which a GCR signal is superimposed is converted into a predetermined IF signal by a down converter,
A video signal obtained by detecting the IF signal is processed by the GCR signal to remove a ghost component and modulated again by a modulator, and the modulation output is upconverted by an up converter to a TV having the same frequency as the received TV signal. In a CATV reception TV signal processing circuit for converting and outputting a signal, a frequency dividing means for dividing the IF signal and a filter for extracting a signal component of the same frequency as the IF signal from a frequency division output of the frequency dividing means. Means for supplying the above-mentioned signal component of the filter means to the modulator as a carrier signal, and a receiving TV signal processing circuit for CATV.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5039273A JP2841006B2 (en) | 1993-02-04 | 1993-02-04 | Receive TV signal processing circuit for CATV |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5039273A JP2841006B2 (en) | 1993-02-04 | 1993-02-04 | Receive TV signal processing circuit for CATV |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06233157A true JPH06233157A (en) | 1994-08-19 |
| JP2841006B2 JP2841006B2 (en) | 1998-12-24 |
Family
ID=12548557
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5039273A Expired - Fee Related JP2841006B2 (en) | 1993-02-04 | 1993-02-04 | Receive TV signal processing circuit for CATV |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2841006B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6184920B1 (en) | 1997-07-17 | 2001-02-06 | Fujitsu Limited | Picture signal transmitting system using CATV network in which the local oscillator is transmitted separately |
| JP2002051319A (en) * | 2000-05-23 | 2002-02-15 | Maspro Denkoh Corp | Frequency converter and communication system |
| JP2005323228A (en) * | 2004-05-11 | 2005-11-17 | Hochiki Corp | Head-end device for terrestrial digital broadcast reception, level adjusting device, and terrestrial digital broadcast community reception system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6024783A (en) * | 1983-07-20 | 1985-02-07 | Toshiba Corp | Carrier extraction type coherent detection system |
| JPS61198882A (en) * | 1985-02-27 | 1986-09-03 | Pioneer Electronic Corp | Synchronous detection circuit |
| JPH02107017A (en) * | 1988-10-15 | 1990-04-19 | Matsushita Electric Ind Co Ltd | Fm demodulator |
-
1993
- 1993-02-04 JP JP5039273A patent/JP2841006B2/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6024783A (en) * | 1983-07-20 | 1985-02-07 | Toshiba Corp | Carrier extraction type coherent detection system |
| JPS61198882A (en) * | 1985-02-27 | 1986-09-03 | Pioneer Electronic Corp | Synchronous detection circuit |
| JPH02107017A (en) * | 1988-10-15 | 1990-04-19 | Matsushita Electric Ind Co Ltd | Fm demodulator |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6184920B1 (en) | 1997-07-17 | 2001-02-06 | Fujitsu Limited | Picture signal transmitting system using CATV network in which the local oscillator is transmitted separately |
| JP2002051319A (en) * | 2000-05-23 | 2002-02-15 | Maspro Denkoh Corp | Frequency converter and communication system |
| JP4681134B2 (en) * | 2000-05-23 | 2011-05-11 | マスプロ電工株式会社 | Frequency converter |
| JP2005323228A (en) * | 2004-05-11 | 2005-11-17 | Hochiki Corp | Head-end device for terrestrial digital broadcast reception, level adjusting device, and terrestrial digital broadcast community reception system |
| JP4623628B2 (en) * | 2004-05-11 | 2011-02-02 | ホーチキ株式会社 | Digital terrestrial broadcast receiving headend device and terrestrial digital broadcast hearing system |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2841006B2 (en) | 1998-12-24 |
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