JP4250020B2 - BS / CS, CATV amplifier - Google Patents

Description

となり、１０ＭＨｚ〜５５ＭＨｚの帯域を持つＣＡＴＶ上り増幅回路４０に障害を与えることになる。
【００２０】
なお、従来、テレビ用ブースタにおいては、アンテナから入力されたテレビ信号の強度を検出し、その信号強度が基準値よりも大きいか否かを判定し、その判定結果を表示部に表示することにより、高価な測定器を使用せずに増幅器の出力レベルを調整できるようにしたものが考えられている（例えば、特許文献１参照。）。
【００２１】
【特許文献１】
特開平９−１３０６８６号公報
【００２２】
【発明が解決しようとする課題】
上記従来のテレビ用ブースタは、アンテナから入力されるテレビ信号（ＶＨＦ、ＵＨＦ）のみを増幅する１系統の増幅器で、自系統において発生する歪みについてのみ考慮した構成となっている。しかし、ＢＳ／ＣＳ、ＣＡＴＶ増幅装置では、多系統の増幅回路を備え、ＢＳ／ＣＳのＴＶ画像に問題がなくても、ＣＡＴＶ上り増幅回路に障害が発生する場合があるので、アンテナから入力されるテレビ信号の増幅系統における歪みの発生を防止しても、ＣＡＴＶ上り増幅回路に影響する歪みの発生を防止することはできない。
【００２３】
本発明は上記の課題を解決するためになされたもので、測定器を使用することなく、ＢＳ／ＣＳ増幅回路の出力レベルが定格となるように調整でき、ＣＡＴＶ増幅回路に影響する歪みの発生を確実に防止し得るＢＳ／ＣＳ、ＣＡＴＶ増幅装置を提供することを目的とする。
【００２４】
【課題を解決するための手段】
本発明は、ＢＳ／ＣＳ増幅回路及びＣＡＴＶ下り／上り増幅回路を備えたＢＳ／ＣＳ、ＣＡＴＶ増幅装置において、前記ＢＳ／ＣＳ増幅回路の出力信号からＣＡＴＶ上り増幅回路と同じ周波数帯域の信号を選択するフィルタと、前記フィルタにより選択された信号を検波する検波器と、前記検波器の出力信号を基準電圧と比較して歪みの発生を検出する比較手段と、前記比較手段の出力信号に基づいて歪みの発生を表示する表示手段とを具備したことを特徴とする。
【００２５】
上記の構成によれば、ＢＳ／ＣＳ増幅回路において信号の過入力により歪みが発生すると、その歪み成分がフィルタにより選択されて検波器により検波され、その後、比較器にて基準電圧との比較により検出されて表示手段に表示される。従って、上記表示手段により歪み発生を確認でき、測定器を使用することなく、ＢＳ／ＣＳ増幅回路の信号出力レベルが定格となるように調整することが可能となり、ＣＡＴＶ上り増幅回路等に影響する歪みの発生を確実に防止することができる。
【００２６】
【発明の実施の形態】
以下、図面を参照して本発明の一実施形態を説明する。
【００２７】
図１は、本発明の一実施形態に係るＢＳ／ＣＳ、ＣＡＴＶ増幅装置５０の構成を示すブロック図で、図２に示したＢＳ／ＣＳ、ＣＡＴＶ増幅装置１０と同一部分には同一符号を付して詳細な説明は省略する。
【００２８】
上記ＢＳ／ＣＳ、ＣＡＴＶ増幅装置５０は、図２に示したＢＳ／ＣＳ、ＣＡＴＶ増幅装置１０と同様に第１の分波器１３と第２の分波器１４との間にＢＳ／ＣＳ増幅回路２０、ＣＡＴＶ下り増幅回路３０及びＣＡＴＶ上り増幅回路４０を備えている。
【００２９】
上記ＢＳ／ＣＳ増幅回路２０は、バンドパスフィルタ２１、ゲインコントロール回路２２、増幅器２３〜２５、バンドパスフィルタ２６により構成されるが、増幅器２５とバンドパスフィルタ２６との間に分岐器５１を設け、その分岐出力端子にＢＳ／ＣＳ歪み検出回路６０を接続している。
【００３０】
上記ＢＳ／ＣＳ歪み検出回路６０は、例えば１０ＭＨｚ〜５５ＭＨｚの周波数を通過させるバンドパスフィルタ６１、増幅器６２、６３、検波器６４、直流増幅器６５、比較器６６、表示器６７からなっている。上記比較器６６には、基準電圧源６８から基準電圧が与えられる。上記基準電圧源６８は、例えば基準電圧を可変設定する電圧設定手段を備えている。基準電圧源６８から出力される基準電圧は、許容する歪みの信号レベルに応じて予め設定される。
【００３１】
上記バンドパスフィルタ６１は、増幅器２５から出力される信号のうち、ＣＡＴＶ上り増幅回路４０に影響する歪み成分、すなわち、１０ＭＨｚ〜５５ＭＨｚの周波数帯域の信号を選択して出力する。上記バンドパスフィルタ６１により選択された信号は、増幅器６２、６３で増幅された後、検波器６４で検波されて直流信号に変換される。この検波器６４の出力信号は、直流増幅器６５で増幅されて比較器６６に入力される。
【００３２】
上記比較器６６は、直流増幅器６５の出力信号と基準電圧源６８から与えられる基準電圧とを比較し、直流増幅器６５の出力信号が基準電圧を超えると表示器６７に信号を出力する。上記比較器６６は、例えばオペアンプ等を用いて構成される。
【００３３】
上記表示器６７は、例えばＬＥＤランプを使用し、比較器６６から出力される信号によりＬＥＤランプを点灯する。
【００３４】
上記ＢＳ／ＣＳ、ＣＡＴＶ増幅装置５０を集合住宅におけるテレビ共同視聴設備として設置した際、表示器６７の表示状態を見ながらゲインコントロール回路２２を調整し、増幅器２３、２４、２５への入力信号が適正レベルとなるように、すなわち、ＣＡＴＶ上り増幅回路４０の周波数帯である１０ＭＨｚ〜５５ＭＨｚで発生する歪みが基準レベル以下となるように設定する。
【００３５】
上記表示器６７のＬＥＤランプが点灯している状態では、増幅器２３、２４、２５への入力信号が過入力で、１０ＭＨｚ〜５５ＭＨｚの周波数帯で基準レベル以上の歪みが発生しているので、ゲインコントロール回路２２のゲインを低下させ、表示器６７のＬＥＤランプが点灯しないようにする。
【００３６】
上記のように表示器６７のＬＥＤランプが点灯している状態でゲインコントロール回路２２を調整し、ＬＥＤランプを消灯させることで、増幅器２３、２４、２５への入力信号を適切なレベルに設定することができる。
【００３７】
なお、上記実施形態では、表示器６７としてＬＥＤランプを使用した場合について示したが、その他の発光表示体を使用しても良く、更には光の他、音や振動等により歪みの発生状態を報知するようにしても良い。
【００３８】
また、上記実施形態では、ＢＳ／ＣＳ歪み検出回路６０は、バンドパスフィルタ６１によりＣＡＴＶ上り増幅回路４０に対する１０ＭＨｚ〜５５ＭＨｚの周波数帯の信号を取り出して信号レベルを判断するようにしたが、ＢＳ／ＣＳ増幅回路２０と同じ９５０ＭＨｚ〜２６１０ＭＨｚの信号を取り出して信号レベルを判断するようにして良い。ＢＳ／ＣＳ増幅回路２０における９５０ＭＨｚ〜２６１０ＭＨｚの信号レベルが基準値より高い場合には、９５０ＭＨｚ〜２６１０ＭＨｚの周波数帯で歪みが発生すると共に、１０ＭＨｚ〜５５ＭＨｚの周波数帯でも歪みが発生するので、ＢＳ／ＣＳ増幅回路２０における９５０ＭＨｚ〜２６１０ＭＨｚの信号レベルによっても、１０ＭＨｚ〜５５ＭＨｚの周波数帯における歪みの発生状態を推測することが可能である。
【００３９】
更に上記実施形態では、ＢＳ／ＣＳ増幅回路２０におけるゲインコントロール回路２２のゲインを手動により調整する場合について示したが、直流増幅器６５の出力信号あるいは比較器６６の出力信号を用いてゲインコントロール回路２２のゲインを自動的に調整して歪みの発生を回避するようにしても良い。
【００４０】
本発明は、上記実施形態そのままに限定されるものではなく、実施段階ではその要旨を逸脱しない範囲で構成要素を変形して具体化できるものである。
【００４１】
【発明の効果】
以上詳記したように本発明によれば、ＢＳ／ＣＳ増幅回路と共にＣＡＴＶ下り／上り増幅回路を備えたＢＳ／ＣＳ、ＣＡＴＶ増幅装置において、ＢＳ／ＣＳ増幅回路で発生する歪みを検出する歪み検出回路を備えているので、ＢＳ／ＣＳ帯域、ＣＡＴＶ上り帯域等に影響する歪みの発生を検出でき、これにより測定器を使用することなく、ＢＳ／ＣＳ増幅回路の信号出力レベルが定格となるように調整して歪みの発生を確実に防止することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係るＢＳ／ＣＳ、ＣＡＴＶ増幅装置の構成を示すブロック図。
【図２】従来のＢＳ／ＣＳ、ＣＡＴＶ増幅装置の構成を示すブロック図。
【符号の説明】
１１、１２…入出力端子
１３、１４…分波器
２０…ＢＳ／ＣＳ増幅回路
２１…バンドパスフィルタ
２２…ゲインコントロール回路
２３〜２５…増幅器
２６…バンドパスフィルタ
３０…ＣＡＴＶ下り増幅回路
３１…バンドパスフィルタ
３２…ゲインコントロール回路
３３〜３５…増幅器
３６…バンドパスフィルタ
４０…ＣＡＴＶ上り増幅回路
４１…バンドパスフィルタ
４２…ゲインコントロール回路
４３〜４５…増幅器
４６…バンドパスフィルタ
５０…ＢＳ／ＣＳ、ＣＡＴＶ増幅装置
５１…分岐器
６０…ＢＳ／ＣＳ歪み検出回路
６１…バンドパスフィルタ
６２、６３…増幅器
６４…検波器
６５…直流増幅器
６６…比較器
６７…表示器
６８…基準電圧源[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a BS / CS and CATV amplifying device used in a television joint viewing facility in an apartment house.
[0002]
[Prior art]
In general, a TV joint viewing facility in an apartment house is provided with a bidirectional amplifying device, and a CATV downstream signal transmitted from a head end device (not shown) via a CATV line or a BS received by a satellite broadcast receiving antenna. / CS signal is amplified and CATV upstream signal is amplified. The CATV upstream signal line is used as an Internet line, for example.
[0003]
FIG. 2 shows a configuration example of a conventional BS / CS / CATV amplifying apparatus 10 that amplifies the BS / CS signal and the CATV downlink / uplink signal.
In FIG. 2, reference numeral 11 denotes a first input / output terminal which is connected to the first duplexer 13 and is connected to the headend device and the satellite broadcast receiving antenna by a coaxial cable (not shown).
[0004]
The head end device receives, for example, VHF and UHF television broadcasts, and transmits the received signal (70 MHz to 770 MHz) to the first input / output terminal 11 via a CATV line. The head end device has a function of an Internet system. The satellite broadcast receiving antenna receives BS broadcast and CS broadcast, converts the received signal into a frequency of, for example, 950 MHz to 2610 MHz by a converter, and transmits the converted signal to the first input / output terminal 11. The VHF and UHF television signals output from the headend device are mixed with the BS / CS signal received by the satellite broadcast receiving antenna and input to the first input / output terminal 11.
[0005]
Reference numeral 12 denotes a second input terminal which is connected to the second duplexer 14 and is connected to a TV receiver and a terminal device such as a personal computer (hereinafter referred to as a personal computer) via a coaxial cable (not shown). The The TV receiver has a function of receiving TV signals of VHF / UHF and BS / CS, for example, and the personal computer has an Internet function, and transmits an Internet signal using a CATV upstream band of 10 to 55 MHz.
[0006]
A BS / CS amplifier circuit 20, a CATV downstream amplifier circuit 30, and a CATV upstream amplifier circuit 40 are provided in parallel between the first duplexer 13 and the second duplexer.
[0007]
The BS / CS amplifier circuit 20 includes, for example, a bandpass filter 21 that passes a signal in a frequency band of 950 MHz to 2610 MHz, a gain control circuit 22, an amplifier 23 to 25, and a bandpass filter that passes a signal in a frequency band of 950 MHz to 2610 MHz. 26, which amplifies the BS / CS signal.
[0008]
The CATV downstream amplifier circuit 30 includes, for example, a bandpass filter 31 that passes signals in a frequency band of 70 MHz to 770 MHz, a gain control circuit 32, amplifiers 33 to 35, and a bandpass filter 36 that passes signals in a frequency band of 70 MHz to 770 MHz. CATV downstream signals such as VHF and UHF TV signals and Internet downstream signals are amplified.
[0009]
The CATV upstream amplification circuit 40 includes, for example, a bandpass filter 41 that passes a signal in a frequency band of 10 MHz to 55 MHz, a gain control circuit 42, an amplifier 43 to 45, and a bandpass filter 46 that passes a signal in a frequency band of 10 MHz to 55 MHz. Thus, the CATV upstream signal, for example, the Internet upstream signal is amplified.
[0010]
The first duplexer 13 and the second duplexer 14 have a frequency of 70 MHz or higher, that is, a frequency of 70 MHz to 770 MHz for the CATV downstream amplifier circuit 30 and a frequency of 950 MHz to 2610 MHz for the BS / CS amplifier circuit 20; A frequency of 55 MHz or less, that is, a frequency of 10 MHz to 55 MHz with respect to the CATV upstream amplifier circuit 40 is demultiplexed.
[0011]
The gain control circuits 22, 32, and 42 of each system are configured using, for example, an amplifier and a variable attenuator, and the level of the output signal can be arbitrarily set by manual operation.
[0012]
In the above configuration, the BS / CS signal received by the satellite broadcast receiving antenna is input to the first duplexer 13 via the first input / output terminal 11, and after being demultiplexed here, the BS / CS signal is received. It is selected by the band pass filter 21 of the CS amplifier circuit 20 and amplified by the amplifiers 23 to 25. The BS / CS signals amplified by the amplifiers 23 to 25 are selected by the bandpass filter 26 and then sent to the TV receiver via the second duplexer 14 and the second input terminal 12.
[0013]
Also, the VHF / UHF TV signal output from the headend device is input to the first duplexer 13 via the first input / output terminal 11, and after being demultiplexed here, the CATV downstream amplifier circuit 30 band-pass filters 31 are selected and amplified by amplifiers 33-35. The VHF / UHF TV signal amplified by the amplifiers 33 to 35 is selected by the band pass filter 36 and then sent to the TV receiver via the second duplexer 14 and the second input terminal 12. .
[0014]
The Internet signal output from the personal computer is input to the second demultiplexer 14 via the second input terminal 12, and after being demultiplexed here, is transmitted by the band-pass filter 41 of the CATV uplink amplifier circuit 40. Selected and amplified by amplifiers 43-45. The Internet signals amplified by the amplifiers 43 to 45 are selected by the band pass filter 46 and then sent to the head end device via the first duplexer 13 and the first input / output terminal 11.
[0015]
The BS / CS and CATV amplifying apparatus 10 can be adjusted by providing gain control circuits 22, 32, and 42 in order to suppress distortion caused by excessive input for each band.
[0016]
When adjusting the output level of the BS / CS amplifier circuit 20, conventionally, a measuring instrument such as a spectrum analyzer or a checker is used to adjust the gain control circuit 22 so that the output level is rated.
[0017]
Even when the above measuring device is used, if it is not calibrated correctly, the measured value is different from the actual level, and accurate adjustment cannot be expected. Further, since the measuring instrument is very expensive, some construction companies make adjustments by estimating from the TV screen without using the measuring instrument when adjusting the gain control circuit 22.
[0018]
For this reason, the actual output may exceed the rating, and distortion may occur from the amplifier. In particular, the distortion component generated in the BS / CS amplifier circuit 20 is not generated in the self-band from the frequency relationship of each channel, but is generated in the band of the CATV upstream amplifier circuit 40, and there is a problem in the TV image of the BS / CS. Even if not, the CATV upstream amplifier circuit 40 may be damaged.
[0019]
For example, since the frequency of the BS5 channel is “1126.2 MHz” and the frequency of the BS7 channel is “1164.56 MHz”, the difference frequency f _CH7-5 is

Thus, the CATV upstream amplifier circuit 40 having a bandwidth of 10 MHz to 55 MHz is disturbed.
[0020]
Conventionally, in a television booster, by detecting the strength of a television signal input from an antenna, determining whether the signal strength is greater than a reference value, and displaying the determination result on a display unit A device that can adjust the output level of an amplifier without using an expensive measuring instrument has been considered (for example, see Patent Document 1).
[0021]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-130686
[Problems to be solved by the invention]
The conventional TV booster is a single-system amplifier that amplifies only TV signals (VHF, UHF) input from an antenna, and has a configuration that takes into account only distortion that occurs in its own system. However, BS / CS and CATV amplifying devices have a multi-system amplifier circuit, and even if there is no problem in the TV image of BS / CS, a failure may occur in the CATV upstream amplifier circuit. Even if the generation of distortion in the amplification system of the TV signal is prevented, the generation of distortion affecting the CATV upstream amplification circuit cannot be prevented.
[0023]
The present invention has been made to solve the above-described problems, and can adjust the output level of the BS / CS amplifier circuit to be rated without using a measuring instrument, thereby generating distortion that affects the CATV amplifier circuit. An object of the present invention is to provide a BS / CS and CATV amplifying device that can reliably prevent the above-described problem.
[0024]
[Means for Solving the Problems]
The present invention selects a signal in the same frequency band as that of a CATV upstream amplifier circuit from an output signal of the BS / CS amplifier circuit in a BS / CS and CATV amplifier device including a BS / CS amplifier circuit and a CATV downstream / upstream amplifier circuit. Based on the output signal of the comparator, the detector for detecting the signal selected by the filter, the comparator for detecting the occurrence of distortion by comparing the output signal of the detector with a reference voltage And display means for displaying the occurrence of distortion.
[0025]
According to the above configuration, when distortion occurs due to excessive input of a signal in the BS / CS amplifier circuit, the distortion component is selected by the filter and detected by the detector, and then compared with the reference voltage by the comparator. Detected and displayed on the display means. Therefore, the occurrence of distortion can be confirmed by the display means, and the signal output level of the BS / CS amplifier circuit can be adjusted to be rated without using a measuring instrument, which affects the CATV upstream amplifier circuit and the like. Generation of distortion can be reliably prevented.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0027]
FIG. 1 is a block diagram showing a configuration of a BS / CS and CATV amplifying apparatus 50 according to an embodiment of the present invention. Components identical with those of BS / CS and CATV amplifying apparatus 10 shown in FIG. Detailed description will be omitted.
[0028]
The BS / CS and CATV amplifying apparatus 50 is configured to amplify BS / CS between the first demultiplexer 13 and the second demultiplexer 14 in the same manner as the BS / CS and CATV amplifying apparatus 10 shown in FIG. The circuit 20 includes a CATV down amplifier circuit 30 and a CATV up amplifier circuit 40.
[0029]
The BS / CS amplifier circuit 20 includes a bandpass filter 21, a gain control circuit 22, amplifiers 23 to 25, and a bandpass filter 26. A branching device 51 is provided between the amplifier 25 and the bandpass filter 26. The BS / CS distortion detection circuit 60 is connected to the branch output terminal.
[0030]
The BS / CS distortion detection circuit 60 includes, for example, a bandpass filter 61 that passes a frequency of 10 MHz to 55 MHz, amplifiers 62 and 63, a detector 64, a DC amplifier 65, a comparator 66, and a display 67. The reference voltage is supplied from the reference voltage source 68 to the comparator 66. The reference voltage source 68 includes voltage setting means for variably setting the reference voltage, for example. The reference voltage output from the reference voltage source 68 is set in advance according to the allowable distortion signal level.
[0031]
The band-pass filter 61 selects and outputs a distortion component affecting the CATV up-amplification circuit 40 among signals output from the amplifier 25, that is, a signal in a frequency band of 10 MHz to 55 MHz. The signal selected by the bandpass filter 61 is amplified by the amplifiers 62 and 63, detected by the detector 64, and converted into a DC signal. The output signal of the detector 64 is amplified by the DC amplifier 65 and input to the comparator 66.
[0032]
The comparator 66 compares the output signal of the DC amplifier 65 with the reference voltage supplied from the reference voltage source 68, and outputs a signal to the display 67 when the output signal of the DC amplifier 65 exceeds the reference voltage. The comparator 66 is configured using, for example, an operational amplifier.
[0033]
The display 67 uses, for example, an LED lamp, and turns on the LED lamp according to a signal output from the comparator 66.
[0034]
When the BS / CS and CATV amplifying device 50 is installed as a television joint viewing facility in an apartment house, the gain control circuit 22 is adjusted while viewing the display state of the display 67, and the input signals to the amplifiers 23, 24, and 25 are The distortion is set so as to be an appropriate level, that is, the distortion generated in the frequency band of 10 MHz to 55 MHz of the CATV uplink amplifier circuit 40 is equal to or lower than the reference level.
[0035]
When the LED lamp of the display 67 is lit, the input signals to the amplifiers 23, 24, and 25 are excessively input, and distortion exceeding the reference level occurs in the frequency band of 10 MHz to 55 MHz. The gain of the control circuit 22 is lowered so that the LED lamp of the display 67 is not lit.
[0036]
As described above, the gain control circuit 22 is adjusted in a state where the LED lamp of the display 67 is turned on, and the LED lamp is turned off to set the input signals to the amplifiers 23, 24, and 25 to appropriate levels. be able to.
[0037]
In the above embodiment, an LED lamp is used as the display 67. However, other light-emitting display bodies may be used. You may make it alert | report.
[0038]
In the above-described embodiment, the BS / CS distortion detection circuit 60 extracts the signal in the frequency band of 10 MHz to 55 MHz for the CATV upstream amplification circuit 40 by the band pass filter 61 and determines the signal level. The signal level may be determined by taking out the same 950 MHz to 2610 MHz signal as the CS amplifier circuit 20. When the signal level of 950 MHz to 2610 MHz in the BS / CS amplifier circuit 20 is higher than the reference value, distortion occurs in the frequency band of 950 MHz to 2610 MHz, and distortion also occurs in the frequency band of 10 MHz to 55 MHz. Even with a signal level of 950 MHz to 2610 MHz in the CS amplifier circuit 20, it is possible to infer the state of occurrence of distortion in the frequency band of 10 MHz to 55 MHz.
[0039]
Further, in the above-described embodiment, the case where the gain of the gain control circuit 22 in the BS / CS amplifier circuit 20 is manually adjusted has been described. However, the gain control circuit 22 using the output signal of the DC amplifier 65 or the output signal of the comparator 66 is shown. The gain may be automatically adjusted to avoid the occurrence of distortion.
[0040]
The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.
[0041]
【The invention's effect】
As described above in detail, according to the present invention, in the BS / CS and CATV amplification apparatus provided with the CATV down / up amplification circuit together with the BS / CS amplification circuit, the distortion detection for detecting the distortion generated in the BS / CS amplification circuit. Since the circuit is provided, it is possible to detect the occurrence of distortion affecting the BS / CS band, the CATV upstream band, etc., so that the signal output level of the BS / CS amplifier circuit is rated without using a measuring instrument. The occurrence of distortion can be reliably prevented by adjusting to the above.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a BS / CS and CATV amplification apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a conventional BS / CS and CATV amplifier.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11, 12 ... Input / output terminal 13, 14 ... Splitter 20 ... BS / CS amplification circuit 21 ... Band pass filter 22 ... Gain control circuit 23-25 ... Amplifier 26 ... Band pass filter 30 ... CATV down amplification circuit 31 ... Band Pass filter 32 ... Gain control circuit 33-35 ... Amplifier 36 ... Band pass filter 40 ... CATV upstream amplification circuit 41 ... Band pass filter 42 ... Gain control circuit 43-45 ... Amplifier 46 ... Band pass filter 50 ... BS / CS, CATV Amplifier 51 ... Branch 60 ... BS / CS distortion detection circuit 61 ... Bandpass filters 62, 63 ... Amplifier 64 ... Detector 65 ... DC amplifier 66 ... Comparator 67 ... Display 68 ... Reference voltage source

Claims (2)

In the BS / CS and CATV amplifying device including a BS / CS amplifying circuit and a CATV down / up amplifying circuit, a filter that selects a signal in the same frequency band as the CATV up amplifying circuit from the output signal of the BS / CS amplifying circuit; A detector for detecting a signal selected by the filter; a comparing means for detecting the occurrence of distortion by comparing an output signal of the detector with a reference voltage; and generating distortion based on the output signal of the comparing means. A BS / CS and CATV amplifying device comprising display means for displaying. In the BS / CS and CATV amplifying device including a BS / CS amplifying circuit and a CATV down / up amplifying circuit, a filter that selects a signal in the same frequency band as the CATV up amplifying circuit from the output signal of the BS / CS amplifying circuit; A detector for detecting a signal selected by the filter; and a signal level adjusting means for adjusting the signal level in the BS / CS amplifier circuit based on the output signal of the detector to avoid the occurrence of distortion. BS / CS, CATV amplification apparatus characterized by the above.

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