JPH02302129A - Video receiver - Google Patents
Video receiverInfo
- Publication number
- JPH02302129A JPH02302129A JP12330889A JP12330889A JPH02302129A JP H02302129 A JPH02302129 A JP H02302129A JP 12330889 A JP12330889 A JP 12330889A JP 12330889 A JP12330889 A JP 12330889A JP H02302129 A JPH02302129 A JP H02302129A
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- tuner
- control
- signal
- agc
- 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
Landscapes
- Television Receiver Circuits (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明はチューナ回路の入力側にアッテネータ回路と
ブースタ回路を備えた映像受信装置に関するものである
。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a video receiving device that includes an attenuator circuit and a booster circuit on the input side of a tuner circuit.
第４図は従来の映像受信装置の構成を示すブロック図で
ある０図において、１はアッテネータ回路（またはブー
スタ回路）で、その入力側はアンテナ２に接続され、出
力側はチューナ回路３に接続されている。チューナ回路
３の出力は映像中間周波検波回路４の入力に接続され、
この映像中間周波検波回路４の出力は映像信号処理回路
５の入力に接続されている。また、映像中間周波検波回
路４の制御出力はＲＦ−ＡＧＣ回路（自動利得制御回路
）１３に入力され、このＲＦ−ＡＣＣ回路６によってチ
ューナ回路３の出力が一定レベルに制御されるよう構成
されている。また、映像信号処理回路５の出力はモニタ
７に接続されている。FIG. 4 is a block diagram showing the configuration of a conventional video receiving device. In FIG. has been done. The output of the tuner circuit 3 is connected to the input of the video intermediate frequency detection circuit 4,
The output of this video intermediate frequency detection circuit 4 is connected to the input of a video signal processing circuit 5. Further, the control output of the video intermediate frequency detection circuit 4 is input to an RF-AGC circuit (automatic gain control circuit) 13, and the RF-ACC circuit 6 is configured to control the output of the tuner circuit 3 to a constant level. There is. Further, the output of the video signal processing circuit 5 is connected to a monitor 7.
次に動作について説明する。Next, the operation will be explained.
アンテナ２で受信した信号は、アッテネータ回路（また
はブースタ回路）１を介してチューナ回路３に供給され
、ここで映像中間周波数に変換されて映像中間周波検波
回路４に送出される。また、映像中間周波検波回路４の
制御出力はＲＦ−ＡＧＣ回路６に入力され、ＲＦ−ＡＧ
Ｃ回路６はこの信号に基づいてチューナ回路３の利得を
制御し、映像中間周波検波回路４への入力レベルが一定
値となるよう制御している。The signal received by the antenna 2 is supplied to the tuner circuit 3 via the attenuator circuit (or booster circuit) 1, where it is converted to a video intermediate frequency and sent to the video intermediate frequency detection circuit 4. Further, the control output of the video intermediate frequency detection circuit 4 is input to the RF-AGC circuit 6, and the RF-AG
The C circuit 6 controls the gain of the tuner circuit 3 based on this signal so that the input level to the video intermediate frequency detection circuit 4 is maintained at a constant value.
映像中間周波検波回路４の検波出力は映像信号処理回路
５に供給され、この映像信号処理回路５で所定の信号処
理が行われ、映像信号となってモニタ７に供給される。The detection output of the video intermediate frequency detection circuit 4 is supplied to the video signal processing circuit 5, where it undergoes predetermined signal processing and is supplied to the monitor 7 as a video signal.
［発明が解決しようとする課題］
従来の映像受信装置は上記のように構成されており、強
電界時の混変調特性の改善および弱電界時のＳ／Ｎ劣化
防止にはＲＦ−ＡＧＣ回路６によるチューナ回路３の利
得制御だけでは十分でなく、チューナ回路３の入力側に
アッテネータ回路またはブースタ回路のいずれかを備え
ている。このため、強電界信号と弱電界信号とが両方存
在する場合はいずれか一方を犠牲にしなければならない
問題があり、また、このような問題を解決するためには
、アッテネータ回路とブースタ回路のそれぞれを設け、
これらを使用者が切換えるようにすればよいが、この切
換操作は非常に煩わしく、かつ確実さを欠くものであっ
て、採用し難いものであった。[Problems to be Solved by the Invention] The conventional video receiving device is configured as described above, and the RF-AGC circuit 6 is used to improve cross-modulation characteristics in strong electric fields and prevent S/N deterioration in weak electric fields. It is not enough to control the gain of the tuner circuit 3 by the above method, but the input side of the tuner circuit 3 is provided with either an attenuator circuit or a booster circuit. For this reason, if both a strong electric field signal and a weak electric field signal exist, there is a problem that one of them must be sacrificed, and in order to solve this problem, it is necessary to established,
Although it would be possible for the user to switch between these, this switching operation is extremely troublesome and lacks reliability, making it difficult to employ.
この発明は上記の問題点を解決するためになされたもの
であって、強弱電界信号が両方存在する場合でも両信号
の混変調特性の改善およびＳ ／ Ｎ劣化防止を行うこ
とのできる映像受信装置を得ることを目的とする。The present invention has been made to solve the above problems, and provides a video receiving device that can improve the cross-modulation characteristics of both strong and weak electric field signals and prevent S/N deterioration even when both strong and weak electric field signals are present. The purpose is to obtain.
〔課題を解決するための手段）
この発明に係る映像受信装置は、ＲＦ−ＡＧＣ回路の出
力信号に基づき、強電界時はアッテネータとチューナ回
路を接続し、弱電界時はブースタ回路とチューナ回路と
を接続する切換手段を設けたものである。[Means for Solving the Problems] A video receiving device according to the present invention connects an attenuator and a tuner circuit in a strong electric field, and connects a booster circuit and a tuner circuit in a weak electric field, based on the output signal of the RF-AGC circuit. It is equipped with a switching means for connecting.
［作 用］
この発明においては、チューナ回路に常に一定の電界が
供給されるため、強電界信号時の混変調や弱電界信号時
のＳ／Ｎ劣化が防止される。また、チューナ回路の利得
制御量を小さくできるため、ＲＦ−ＡＧＣ回路の出力を
チューナ回路の出力に合わせて調整しなくても、チュー
ナ回路の利得制御量はＲＦ−ＡＧＣ回路の出力範囲で十
分にカバーされる。[Function] In the present invention, since a constant electric field is always supplied to the tuner circuit, cross-modulation in the case of strong electric field signals and S/N deterioration in the case of weak electric field signals are prevented. In addition, since the gain control amount of the tuner circuit can be made small, the gain control amount of the tuner circuit can be sufficiently controlled within the output range of the RF-AGC circuit without having to adjust the output of the RF-AGC circuit according to the output of the tuner circuit. covered.
第１図はこの発明の一実施例による映像受信装置の構成
を示す図である０図中、８，９はチューナ回路３の入力
側に設けられたアッテネータ回路およびブースタ回路で
、それぞれチューナ回路３とは切換えスイッチ１０ａを
介して接続されるようになっている。また、ｔａｂはア
ンテナ２とチューナ回路３との間に接続された切換えス
イッチ、１１はＲＦ−ＡＧＣ回路６の出力に基づいて切
換えスイッチ１０ａ、１０ｂの切換制御を行うと共に、
アッテネータ回路８の減衰量、ブースタ回路９の増幅量
を制御する減衰量・増幅量制御回路（以下、制御回路と
略す）である、他の各構成は従来と同様であるため対応
する部分に同一符号を付してその説明を省略する。FIG. 1 is a diagram showing the configuration of a video receiving device according to an embodiment of the present invention. In FIG. and is connected via a changeover switch 10a. Further, tab is a changeover switch connected between the antenna 2 and the tuner circuit 3, and 11 is a changeover switch that controls changeover switches 10a and 10b based on the output of the RF-AGC circuit 6.
This is an attenuation/amplification control circuit (hereinafter referred to as the control circuit) that controls the attenuation of the attenuator circuit 8 and the amplification of the booster circuit 9.The other configurations are the same as the conventional ones, so the corresponding parts are the same. Reference numerals are given and explanations thereof are omitted.
次に動作について説明する。アンテナ２により受信され
た信号は、切換えスイッチ１０ｂを介してチューナ回路
３にイ共給され、この子ューナ回路３で映像中間周波数
に変換される。映像中間周波数信号は映像中間周波検波
回路４に供給されて検波され、更にこの検波された映像
信号は映像信号処理回路５で所定の信号処理が行われ、
モニタ７に供給される。また、ＲＦ−ＡＧＣ回路６は中
間周波検波回路４からの制御信号に基づき利得制御信号
をチューナ回路３および制御８回路１１に送出する。こ
の利得制御信号が最大（フルゲイン信号）の場合、制御
回路１１は切換えスイッチ１０ｂをオフ、切換えスイッ
チ１０ａをブースタ回路９側に接続させ、かつＲＦ−Ａ
ＧＣ回路６の出力が最適値となるようその増幅量を制御
する。また、逆にＲＦ−ＡＧＣ回路６の出力が最小の場
合、制御回路１１は切換えスイッチ１０ｂをオフ、切換
えスイッチ１０ａをアッテネータ８側に接続させ、ＲＦ
−ＡＧＣ回路６の出力が最適値となるようその減衰量を
制御する。これによりチューナ回路３の利得減衰量を小
さく設定できるためＲＦ −ＡＧＣ回路６の無調整化が
可能となる。Next, the operation will be explained. The signal received by the antenna 2 is fed to the tuner circuit 3 via the changeover switch 10b, and is converted into a video intermediate frequency by the tuner circuit 3. The video intermediate frequency signal is supplied to the video intermediate frequency detection circuit 4 and detected, and the detected video signal is further subjected to predetermined signal processing in the video signal processing circuit 5.
The signal is supplied to the monitor 7. Further, the RF-AGC circuit 6 sends a gain control signal to the tuner circuit 3 and the control circuit 11 based on the control signal from the intermediate frequency detection circuit 4. When this gain control signal is the maximum (full gain signal), the control circuit 11 turns off the changeover switch 10b, connects the changeover switch 10a to the booster circuit 9 side, and
The amount of amplification is controlled so that the output of the GC circuit 6 becomes an optimum value. Conversely, when the output of the RF-AGC circuit 6 is the minimum, the control circuit 11 turns off the changeover switch 10b, connects the changeover switch 10a to the attenuator 8 side, and
- Control the amount of attenuation so that the output of the AGC circuit 6 has an optimum value. As a result, the gain attenuation amount of the tuner circuit 3 can be set to a small value, so that the RF-AGC circuit 6 can be made unadjusted.
すなわちこれを詳細に説明すると、先ず従来では第２図
に示す、ように中電界（８５ｄＢμ）におけるノイズ領
域と混変調領域との幅が等間隔になるようＲＦ−ＡＧＣ
回路６のＡＧＣ電圧（利得制御信号）が設定されていた
。また、一般の映像受信装置においては入力が約６０ｄ
Ｂ前後でチューナ回路３がフルゲインになるよう設定さ
れており、調整時点（中電界）でのゲイン・リダクシヨ
ン（Ｇ−Ｒ）量は約３０ｄＢ前後に設定されている。That is, to explain this in detail, first, in the past, as shown in FIG.
The AGC voltage (gain control signal) of circuit 6 was set. In addition, in a general video receiving device, the input is approximately 60 d.
The tuner circuit 3 is set to have full gain before and after B, and the amount of gain reduction (GR) at the time of adjustment (medium electric field) is set to about 30 dB.
しかしながらチューナ回路３の３０ｄＢＧ−Ｒ時のＡＣ
Ｃ電圧の幅は第３図に示すように１．５ Ｖ前後である
ため、第２図に示したノイズ・混炭ＩＭ 領域幅１．０
〜１．５ｖではカバーしきれない、このため本実施例で
はアッテネータ回路８とブースタ回路９によってチュー
ナ回路３に一定の電界を供給し、またチューナ回路３の
Ｇ・Ｒ量を２０ｄＢ弱に設定することによりＡＧＣ電圧
の幅を１．０ Ｖ以下とする。この場合、Ｇ−Ｒ量２０
ｄＢ前後のノイズ・混変調領域は第２図に示すように１
．５ Ｖ以上あるため、チューナ回路３のＡＧＣ電圧幅
を十分にカバーする。従って、従来のようにＲＦ−ＡＧ
Ｃ回路６の設定値をチューナ回路３の出力に合わせて調
整する必要がなく、チューナ回路３の数値のばらつきを
考慮しても、ＲＦ−ＡＧＣ回路６は無調整でそのばらつ
きを十分にカバーすることができる。However, the AC of tuner circuit 3 at 30dBG-R
Since the width of the C voltage is around 1.5 V as shown in Figure 3, the width of the noise/mixed coal IM region shown in Figure 2 is 1.0.
~1.5V cannot cover the voltage, so in this embodiment, a constant electric field is supplied to the tuner circuit 3 by the attenuator circuit 8 and the booster circuit 9, and the G/R amount of the tuner circuit 3 is set to a little less than 20 dB. This makes the width of the AGC voltage 1.0 V or less. In this case, the G-R amount is 20
The noise/cross modulation area around dB is 1 as shown in Figure 2.
．． Since it is 5 V or more, it sufficiently covers the AGC voltage width of the tuner circuit 3. Therefore, as in the past, RF-AG
There is no need to adjust the setting value of the C circuit 6 according to the output of the tuner circuit 3, and even if variations in the numerical values of the tuner circuit 3 are considered, the RF-AGC circuit 6 can sufficiently cover the variations without adjustment. be able to.
以上のようにこの発明によれば、入力信号の電界強度に
関係な（一定の電界強度の信号をチューナ回路に供給す
るよう構成したので、強弱電界信 、号が存在する場合
でも混変調およびＳ／Ｎ劣化を防止することができ、ま
たＲＦ−ＡＧＣ回路の無調整化が可能となる効果がある
。As described above, according to the present invention, since the tuner circuit is configured to supply a signal with a constant field strength that is related to the field strength of the input signal, cross modulation and S /N deterioration can be prevented, and the RF-AGC circuit can be made without adjustment.
第１図はこの発明の一実施例による映像受信装置のブロ
ック図、第２図は入力電界に対するＡＧＣ電圧の関係を
示す図、第３図はＡＧＣ電圧に対するチューナ回路のゲ
イン・リダクション量の関係を示す図、第４図は従来の
映像受信装置のブロック図である。
３・・・チューナ回路、６・・・ＲＦ−ＡＧＣ回路、８
・・・アッテネータ回路、９・・・ブースタ回路、１０
ａ。
１０ｂ・・・切換えスイッチ、１１は減衰量・増幅量制
御回路。
なお、図中同一符号は同一または相当部分を示す。FIG. 1 is a block diagram of a video receiving device according to an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between the AGC voltage and the input electric field, and FIG. 3 is a diagram showing the relationship between the amount of gain reduction of the tuner circuit and the AGC voltage. The figure shown in FIG. 4 is a block diagram of a conventional video receiving device. 3... Tuner circuit, 6... RF-AGC circuit, 8
...Attenuator circuit, 9...Booster circuit, 10
a. 10b... changeover switch; 11 is an attenuation/amplification amount control circuit; Note that the same reference numerals in the figures indicate the same or corresponding parts.
Claims (1)
よびブースタ回路と、前記チューナ回路の利得制御を行
うＲＦ−ＡＧＣ回路と、このＲＦ−ＡＧＣ回路の出力信
号に基づき、強電界時は前記アッテネータ回路とチュー
ナ回路を接続し、弱電界時は前記ブースタ回路とチュー
ナ回路を接続する切換手段を備えた映像受信装置。An attenuator circuit and a booster circuit provided on the input side of the tuner circuit, an RF-AGC circuit that performs gain control of the tuner circuit, and an output signal of the RF-AGC circuit that controls the attenuator circuit and the tuner circuit in the event of a strong electric field. A video receiving device comprising a switching means for connecting the circuits and for connecting the booster circuit and the tuner circuit when the electric field is weak.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12330889A JPH02302129A (en) | 1989-05-17 | 1989-05-17 | Video receiver |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12330889A JPH02302129A (en) | 1989-05-17 | 1989-05-17 | Video receiver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02302129A true JPH02302129A (en) | 1990-12-14 |
Family
ID=14857327
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12330889A Pending JPH02302129A (en) | 1989-05-17 | 1989-05-17 | Video receiver |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02302129A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0344377U (en) * | 1989-08-31 | 1991-04-24 | ||
| JP2004510379A (en) * | 2000-09-25 | 2004-04-02 | トムソン ライセンシング ソシエテ アノニム | Method for optimizing the level of an RF signal by comparing the quality of the RF signal under different operating modes |
| JP2008153845A (en) * | 2006-12-15 | 2008-07-03 | Hitachi Media Electoronics Co Ltd | Digital broadcast receiver |
| JP2010068529A (en) * | 1994-12-16 | 2010-03-25 | Qualcomm Inc | Method and apparatus for increasing receiver immunity to interference |
| US8233869B2 (en) | 2006-12-11 | 2012-07-31 | Thomson Licensing | Automatic gain control with improved cross-modulation |
-
1989
- 1989-05-17 JP JP12330889A patent/JPH02302129A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0344377U (en) * | 1989-08-31 | 1991-04-24 | ||
| JP2010068529A (en) * | 1994-12-16 | 2010-03-25 | Qualcomm Inc | Method and apparatus for increasing receiver immunity to interference |
| JP2004510379A (en) * | 2000-09-25 | 2004-04-02 | トムソン ライセンシング ソシエテ アノニム | Method for optimizing the level of an RF signal by comparing the quality of the RF signal under different operating modes |
| US8233869B2 (en) | 2006-12-11 | 2012-07-31 | Thomson Licensing | Automatic gain control with improved cross-modulation |
| JP2008153845A (en) * | 2006-12-15 | 2008-07-03 | Hitachi Media Electoronics Co Ltd | Digital broadcast receiver |
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