JPH0346418A - Squelch detection circuit - Google Patents
Squelch detection circuitInfo
- Publication number
- JPH0346418A JPH0346418A JP18201189A JP18201189A JPH0346418A JP H0346418 A JPH0346418 A JP H0346418A JP 18201189 A JP18201189 A JP 18201189A JP 18201189 A JP18201189 A JP 18201189A JP H0346418 A JPH0346418 A JP H0346418A
- Authority
- JP
- Japan
- Prior art keywords
- detection voltage
- noise
- signal
- squelch
- voltage
- 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
- 238000001514 detection method Methods 0.000 title claims abstract description 54
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 1
Landscapes
- Noise Elimination (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明はスケルチ検出回路に関し、特にマイクロ波ヘテ
ロダイン中継機等で使用されるスケルチ検出回路に関す
る。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a squelch detection circuit, and particularly to a squelch detection circuit used in a microwave heterodyne repeater or the like.
第２図にマイクロ波ヘテロダイン中継機等で使用されて
いる従来のスケルチ検出回路を示す。図において、ｌは
中間周波帯域ろ波器、２は主中間周波増幅器、３は検波
器、４は利得制御増幅器、５は電圧比較器である。FIG. 2 shows a conventional squelch detection circuit used in microwave heterodyne repeaters and the like. In the figure, l is an intermediate frequency band filter, 2 is a main intermediate frequency amplifier, 3 is a detector, 4 is a gain control amplifier, and 5 is a voltage comparator.
このスケルチ検出回路では、主中間周波増幅器２の出力
の一部を検波器３で検波して信号検波電圧を得るととも
に、この信号検波電圧に基づいて利得制御増幅器４で利
得制御電圧を生威し、主中間周波増幅器２を帰還制御す
る。そして、この利得制御電圧を電圧比較器５において
基準電圧と比較することでスケルチ点を検出している。In this squelch detection circuit, a part of the output of the main intermediate frequency amplifier 2 is detected by a detector 3 to obtain a signal detection voltage, and a gain control voltage is generated by a gain control amplifier 4 based on this signal detection voltage. , performs feedback control on the main intermediate frequency amplifier 2. The squelch point is detected by comparing this gain control voltage with a reference voltage in a voltage comparator 5.
上述した従来のスケルチ検出回路においては、スケルチ
点を検出するのに、主中間周波増幅器２の利得制御電圧
を電圧比較器５にて比較しているが、温度等による利得
制御電圧の変動によりスケルチ検出点の入力レベルが温
度変動を起こし易く、常に一定な信号と雑音のレベル差
となるスケルチ点とすることができないという問題があ
る。In the above-mentioned conventional squelch detection circuit, the gain control voltage of the main intermediate frequency amplifier 2 is compared by the voltage comparator 5 to detect the squelch point. There is a problem in that the input level at the detection point is susceptible to temperature fluctuations, and it is not possible to set the squelch point at a constant level difference between the signal and noise.
本発明はスケルチ検出点の温度変動を解消したスケルチ
検出回路を提供することを目的とする。SUMMARY OF THE INVENTION An object of the present invention is to provide a squelch detection circuit that eliminates temperature fluctuations at a squelch detection point.
本発明のスケルチ検出回路は、信号を検波して信号検波
電圧を出力する検波器と、信号帯域外に存在する雑音信
号を検波して雑音検波電圧を出力する検波器と、前記信
号検波電圧と雑音検波電圧とを比較してスケルチ点を検
出する電圧比較器とを備えている。The squelch detection circuit of the present invention includes a detector that detects a signal and outputs a signal detection voltage, a detector that detects a noise signal existing outside the signal band and outputs a noise detection voltage, and a detector that detects a signal and outputs a signal detection voltage. The squelch point is detected by comparing the squelch point with the noise detection voltage.
この構成では、信号検波電圧を利用して利得制御を行う
構成では、得られる雑音検波電圧が信号検波電圧に相関
して変化されることになり、利得の温度変動に伴う検波
電圧の変動を吸収し、スケルチ点を安定に検出すること
が可能となる。In this configuration, in a configuration that performs gain control using the signal detection voltage, the resulting noise detection voltage changes in correlation with the signal detection voltage, absorbing fluctuations in the detection voltage due to temperature fluctuations in the gain. This makes it possible to stably detect the squelch point.
次に、本発明を図面を参照して説明する。 Next, the present invention will be explained with reference to the drawings.
第１図は本発明の一実施例のブロック回路図である。図
において、１は中間周波帯域ろ波器、２は主中間周波増
幅器、３は検波器、４は利得制御増幅器、５は電圧比較
器である。また、６は信号帯域外に同調したろ波器、７
は帯域外雑音検出用検波器であり、前記主中間周波増幅
器２の出力側に接続している。なお、前記電圧比較器５
は、ここでは前記検波器３から出力される信号検波電圧
と、前記帯域外雑音検出用検波器７から出力される帯域
外雑音検波電圧を比較するように構成している。FIG. 1 is a block circuit diagram of one embodiment of the present invention. In the figure, 1 is an intermediate frequency band filter, 2 is a main intermediate frequency amplifier, 3 is a detector, 4 is a gain control amplifier, and 5 is a voltage comparator. Further, 6 is a filter tuned outside the signal band, and 7 is a filter tuned outside the signal band.
is a detector for detecting out-of-band noise, and is connected to the output side of the main intermediate frequency amplifier 2. Note that the voltage comparator 5
Here, the signal detection voltage output from the detector 3 and the out-of-band noise detection voltage output from the out-of-band noise detection detector 7 are compared.
この構成のスケルチ検出回路においては、主中間周波増
幅器２の出力を検波器３で検波し、かつ利得制御増幅器
４で利得制御電圧を生成して主中間周波増幅器２を帰還
制御することはこれまでと同じである。In the squelch detection circuit with this configuration, the output of the main intermediate frequency amplifier 2 is detected by the detector 3, and the gain control amplifier 4 generates a gain control voltage to feedback control the main intermediate frequency amplifier 2. is the same as
一方、主中間周波増幅器２の出力の一部は、帯域外ろ波
器６を通した雑音成分が雑音検出用検波器７で検波され
る。そして、前記検波器３の信号検波電圧と雑音検波電
圧とを電圧比較器５で比較し、この比較結果からスケル
チ点を検出している。On the other hand, a part of the output of the main intermediate frequency amplifier 2 passes through an out-of-band filter 6, and a noise component is detected by a noise detection detector 7. Then, the signal detection voltage of the detector 3 and the noise detection voltage are compared by a voltage comparator 5, and the squelch point is detected from the comparison result.
このため、中間周波帯域ろ波器１を通り主中間周波増幅
器２に入力される信号レベルの高い時は主中間周波増幅
器２の利得が小さＳ、その主中間周波増幅器２からの雑
音レベルは低くなり、雑音検波電圧は低くなる。また、
入力信号レベルが低下した時は主中間周波増幅器の利得
が大きくなり、その出力雑音レベルも高くなり、雑音検
波電圧も高くなる。Therefore, when the signal level input to the main intermediate frequency amplifier 2 through the intermediate frequency band filter 1 is high, the gain of the main intermediate frequency amplifier 2 is small S, and the noise level from the main intermediate frequency amplifier 2 is low. Therefore, the noise detection voltage becomes low. Also,
When the input signal level decreases, the gain of the main intermediate frequency amplifier increases, its output noise level also increases, and the noise detection voltage also increases.
したがって、雑音検波電圧と信号検波電圧を電圧比較器
５により比較してスケルチ点を決定すれば、スケルチ点
は信号レベルと雑音レベルの差が常に一定な点に設定す
ることが可能となる。Therefore, by comparing the noise detection voltage and the signal detection voltage with the voltage comparator 5 to determine the squelch point, the squelch point can be set at a point where the difference between the signal level and the noise level is always constant.
以上説明したように本発明は、信号検波電圧と雑音検波
電圧とを電圧比較器において比較することでスケルチ点
を検出しているので、雑音検波電圧と信号検波電圧とが
互いに相関して変化されることになり、利得の温度変動
に伴う検波電圧の変動を吸収し、スケルチ点を常に一定
の点に設定することができる効果がある。As explained above, the present invention detects the squelch point by comparing the signal detection voltage and the noise detection voltage in a voltage comparator, so that the noise detection voltage and the signal detection voltage are changed in correlation with each other. This has the effect of absorbing fluctuations in the detected voltage due to temperature fluctuations in the gain, and making it possible to always set the squelch point at a constant point.
第１図は本発明の一実施例のブロック回路図、第２図は
従来のスケルチ検出回路の一例のブロック回路図である
。
１・・・中間周波帯域ろ波器、２・・・主中間周波増幅
器、３・・・検波器、
４・・・利得制御増幅器、
５・・・電圧比較
器、
６・・・帯域外ろ波器、
７・・・雑音検出用検波器。FIG. 1 is a block circuit diagram of an embodiment of the present invention, and FIG. 2 is a block circuit diagram of an example of a conventional squelch detection circuit. DESCRIPTION OF SYMBOLS 1...Intermediate frequency band filter, 2...Main intermediate frequency amplifier, 3...Detector, 4...Gain control amplifier, 5...Voltage comparator, 6...Out-of-band filter Wave detector, 7... Wave detector for noise detection.
Claims (1)
ルチ検出回路において、信号を検波して信号検波電圧を
出力する検波器と、信号帯域外に存在する雑音信号を検
波して雑音検波電圧を出力する検波器と、前記信号検波
電圧と雑音検波電圧とを比較してスケルチ点を検出する
電圧比較器とを備えることを特徴とするスケルチ検出回
路。1. In squelch detection circuits used in microwave heterodyne repeaters, etc., there is a detector that detects a signal and outputs a signal detection voltage, and a detector that detects a noise signal that exists outside the signal band and outputs a noise detection voltage. A squelch detection circuit comprising: a detector; and a voltage comparator that compares the signal detection voltage and the noise detection voltage to detect a squelch point.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18201189A JPH0346418A (en) | 1989-07-14 | 1989-07-14 | Squelch detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18201189A JPH0346418A (en) | 1989-07-14 | 1989-07-14 | Squelch detection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0346418A true JPH0346418A (en) | 1991-02-27 |
Family
ID=16110769
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18201189A Pending JPH0346418A (en) | 1989-07-14 | 1989-07-14 | Squelch detection circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0346418A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009017483A (en) * | 2007-07-09 | 2009-01-22 | Hitachi Kokusai Electric Inc | Determination circuit, squelch device, and determination method |
| JP2009055506A (en) * | 2007-08-29 | 2009-03-12 | Icom Inc | Reception device, squelch level setting method and program |
| JP2012095365A (en) * | 2012-02-16 | 2012-05-17 | Icom Inc | Receiving device, squelch level setting method, and program |
-
1989
- 1989-07-14 JP JP18201189A patent/JPH0346418A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009017483A (en) * | 2007-07-09 | 2009-01-22 | Hitachi Kokusai Electric Inc | Determination circuit, squelch device, and determination method |
| JP2009055506A (en) * | 2007-08-29 | 2009-03-12 | Icom Inc | Reception device, squelch level setting method and program |
| JP2012095365A (en) * | 2012-02-16 | 2012-05-17 | Icom Inc | Receiving device, squelch level setting method, and program |
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