JPH03160823A - Multi-path disturbance eliminating circuit - Google Patents
Multi-path disturbance eliminating circuitInfo
- Publication number
- JPH03160823A JPH03160823A JP1300248A JP30024889A JPH03160823A JP H03160823 A JPH03160823 A JP H03160823A JP 1300248 A JP1300248 A JP 1300248A JP 30024889 A JP30024889 A JP 30024889A JP H03160823 A JPH03160823 A JP H03160823A
- Authority
- JP
- Japan
- Prior art keywords
- signal
- circuit
- mute
- electric field
- muting
- 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
- 238000001514 detection method Methods 0.000 claims abstract description 27
- 230000005684 electric field Effects 0.000 claims abstract description 24
- 239000003990 capacitor Substances 0.000 claims abstract description 9
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 7
- 230000007423 decrease Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000003321 amplification Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 101710162453 Replication factor A Proteins 0.000 description 1
- 102100035729 Replication protein A 70 kDa DNA-binding subunit Human genes 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 239000006187 pill Substances 0.000 description 1
Abstract
Description
【発明の詳細な説明】
（イ）産業上の利用分野
本発明は、マルチパス妨害を受けたとき、受信機からノ
イズが発生するのを防止するマルチバス妨害除去回路に
関するものである。DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a multi-bus interference removal circuit that prevents noise from being generated from a receiver when receiving multi-path interference.
（ロ）従来の技術
カーラジオの如き車載用ラジオ受信機においては、自動
車の走行に応じて受信信号の電界強度が変化する．特に
、ピルの谷間等を走行すると前記電界強度が極く弱くな
り、ノイズレベルが急激に上昇するという問題があった
．これを防止する為、一般に受信機にはソフトミューテ
ィング（以下ミュートと称す）回路が設けられており、
第２図に示ｔ如く、弱電界になるにつれて徐々にミュー
トをかけ信号レヘルを徐々に減少させるとともに、ノイ
ズの低減を計っている。第２図において、実線（イ）は
、ソフトミュートをかけない場合の信号レベルを示し、
一点鎖線（口）は、ソフトミュートをかけたときの信号
レベルを示し、実線（ハ）はソフトミュートをかけない
場合のノイズレベルを示し、一点鎖線（二）はソフトミ
ュートをかけた場合のノイズレベルを示す。しかして、
この様にソフトミュートをかけれは、弱電界時にノイズ
レベルがコ，激に上昇するのを防止出来、聴感の改善を
計ることが出来る。(b) Conventional technology In in-vehicle radio receivers such as car radios, the electric field strength of the received signal changes as the vehicle travels. In particular, there was a problem in that when driving through pill valleys, the electric field strength became extremely weak and the noise level rose rapidly. To prevent this, receivers are generally equipped with a soft muting (hereinafter referred to as mute) circuit.
As shown in FIG. 2, as the electric field becomes weaker, muting is applied gradually to gradually reduce the signal level and reduce noise. In Figure 2, the solid line (A) indicates the signal level when soft muting is not applied.
The dashed line (opening) shows the signal level when soft mute is applied, the solid line (c) shows the noise level when soft mute is not applied, and the dashed dotted line (2) shows the noise level when soft mute is applied. Indicates level. However,
By applying soft mute in this way, it is possible to prevent the noise level from increasing dramatically in the case of a weak electric field, and it is possible to improve the audibility.
（ハ）発明が解決しようとする課題
しかしながら、前記ソフトミュート回路は、徐々にミュ
ー１・をかけるという本来の性質を有するので、コンデ
ンサを必須とし、マルチパス妨害時の如き急激な軍界強
度変化に対処することが出来ず、何らかの対策が待たれ
ていた。(c) Problems to be Solved by the Invention However, since the above-mentioned soft mute circuit has the inherent property of gradually applying mu1. Unable to deal with the situation, some kind of countermeasure was awaited.
（二）課題を解決するための手段
本発明は、上述の点に鑑み成されたもので、受信信号の
電界強度を検出する検出手段と、該検出手段の出力信号
に応じたミュート駆動信号を発生ずる駆動段と、前記ミ
ュート駆動信号に応してソフトミュート信号を発生する
ミュート信号発生手段と、前記ソフトミュート信号に応
じて信号路をミュートするミュート手段と、前記検出手
段の出力信号中に含まれる所定レベル以上の交流信号を
検出する交流信号検出手段と、該交流信号検出手段の出
力信号に応じて前記ミュート手段の動作を速める手段と
によって構戒される。(2) Means for Solving the Problems The present invention has been made in view of the above points, and includes a detection means for detecting the electric field strength of a received signal, and a mute drive signal according to the output signal of the detection means. a mute signal generation means for generating a soft mute signal in response to the mute drive signal; a mute means for muting a signal path in response to the soft mute signal; This is achieved by an AC signal detecting means for detecting an AC signal of a predetermined level or higher, and a means for accelerating the operation of the muting means in response to an output signal of the AC signal detecting means.
（ネ）作用
本発明に依れば、マルチバス妨害の発生を検出手段の出
力信号中に含まれる所定レベル以上の交流信号を検出す
ることにより検知し、ミュート手段の動作を速めている
ので、ソフトミュートを行なう系路を利用して、マルチ
バス妨害時のノイズを大幅に低減することが出来る。(f) Effect According to the present invention, the occurrence of multi-bus interference is detected by detecting an AC signal of a predetermined level or higher included in the output signal of the detection means, and the operation of the muting means is accelerated. By using a soft mute path, it is possible to significantly reduce noise caused by multi-bus interference.
（へ）実施例
第１図は、本発明の一実施例を示す回路図で、（１）は
アンテナ、（２）は該アンテナ（１）に受信されたＲＦ
信号を増幅するＲＦ増幅回路、（３〉は増幅されたＲＦ
信号と局部発振回路（４）から得られる局部発振信号と
を混合してＩＦ信号を発生する混合回路、（５）は前記
ＩＦ信号を増幅するＩＦ増幅回路、〈６〉はＩＦ信号を
ＦＭ検波する検波回路、（７）は該検波回路（６）の出
力信号をミュートするミュート回路、（８）はＩＦ信号
をレベル検波することにより受信信号の電界強度を検出
する検出回路、（９）は該検出回路（８〉の出力信号に
応じてミュート駆動信号を発生する駆動回路、（１０）
はコンデンサ〈１１〉を含み前記駆動回路（９）の出力
信号に応してソフトミュート信号を発生するミュート信
号発生回路、〈１２）は前記検出回路（８）の出力信号
中に含まれる所定レベル以上の交流信号を検出する交流
信号検出回路、（１３）は該交流信号検出回路（１２）
の出力信号に応じて、前記コンデンサ（１１）を急速充
電する急速充電回路、及び（ｌ４）は受信信号の電界強
度が所定レベル以下になったことを判別し、交流信号検
出回路（１２〉の動作を停止させる判別回路である。(F) Embodiment FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which (1) is an antenna, and (2) is an RF signal received by the antenna (1).
RF amplification circuit that amplifies the signal, (3> is the amplified RF
A mixing circuit that generates an IF signal by mixing the signal and a local oscillation signal obtained from the local oscillation circuit (4), (5) an IF amplification circuit that amplifies the IF signal, and <6> an FM detection circuit for the IF signal. (7) is a mute circuit that mutes the output signal of the detection circuit (6); (8) is a detection circuit that detects the electric field strength of the received signal by level-detecting the IF signal; (9) is a detection circuit that detects the electric field strength of the received signal by level-detecting the IF signal; a drive circuit (10) that generates a mute drive signal in response to the output signal of the detection circuit (8);
is a mute signal generation circuit that includes a capacitor <11> and generates a soft mute signal in response to the output signal of the drive circuit (9); and <12) is a predetermined level included in the output signal of the detection circuit (8). An AC signal detection circuit (13) detects the above AC signals, and (13) is the AC signal detection circuit (12).
The quick charging circuit (14) quickly charges the capacitor (11) according to the output signal of the AC signal detection circuit (12), which determines that the electric field strength of the received signal has fallen below a predetermined level. This is a discrimination circuit that stops the operation.
次に動作を説明する。アンテナ（１）に受信される受信
信号の電界強度が犬である場合、受信信号の電界強度を
検出する検出回路（８）の出力レベルが大となり、駆動
回路（９）からはミュート駆動信号が発生せず、ミュー
ト信号発生回路（１０）及びミュート回路（７）は動作
しない。その為、検波回路（６〉の出力信号は、ミュー
ト回路（７）を通過し、出力端子（１５）に導出される
。Next, the operation will be explained. When the electric field strength of the received signal received by the antenna (1) is high, the output level of the detection circuit (8) that detects the electric field strength of the received signal becomes high, and the mute drive signal is output from the drive circuit (9). No signal is generated, and the mute signal generation circuit (10) and mute circuit (7) do not operate. Therefore, the output signal of the detection circuit (6>) passes through the mute circuit (7) and is led out to the output terminal (15).
受信信号の電界強度が低下すると、検出回路〈８〉が前
記低下を検出し、それに応じて駆動回路〈９〉からミュ
ート駆動信号が発生し、コンデンサ（１ｌ）の充電が開
始される。前記コンデンサ（１１）が充電されるにつれ
、ミュート信号発生回路（１０）から発生するソフトミ
ュート信号が犬になり、それに応じてミュート回路（７
）の導通が減じられる。When the electric field strength of the received signal decreases, the detection circuit <8> detects the decrease, and in response, a mute drive signal is generated from the drive circuit <9>, and charging of the capacitor (1l) is started. As said capacitor (11) is charged, the soft mute signal generated from the mute signal generating circuit (10) becomes dog and the mute circuit (7) responds accordingly.
) conduction is reduced.
その結果、第２図一点鎖線（口）及び（二〉の如く、電
界強度に応して信号及びノイズレベルが低下し、ソフト
ミュートによるノイズ低減が計れる。As a result, the signal and noise levels decrease in accordance with the electric field strength, as shown by the dashed-dotted lines (opening) and (2) in FIG. 2, and noise reduction can be achieved by soft muting.
マルチバス妨害が生じた場合、電界強度を検出する検出
回路（８）の出力信号中に、大レベルの交流信号が生じ
る．交流信号検出回路（１２）は、前記大レベルの交流
信号を検出し、マルチパス妨害であると判断して急速充
電回路（１３）を駆動する．その為、ミュート信号発生
回路（１０）のコンデンサ（ｌｌ）が急速充電され、前
記ミュート信号発生（ロ）路（１０）から直ちにミュー
ティング信号が発生するので、ミュート回路（７）も直
ちにミュート動作を行ない、その結果ノイズの低減が達
成される。When multi-bus interference occurs, a high-level alternating current signal is generated in the output signal of the detection circuit (8) that detects the electric field strength. The AC signal detection circuit (12) detects the high level AC signal, determines that it is multipath interference, and drives the quick charging circuit (13). Therefore, the capacitor (ll) of the mute signal generation circuit (10) is rapidly charged, and a muting signal is immediately generated from the mute signal generation (b) path (10), so that the mute circuit (7) also performs the mute operation immediately. As a result, noise reduction is achieved.
ところで、受信信号の電界強度が弱い場合、ホワイトノ
イズレベルが上昇し、このホワイトノイズが電界強度を
検出する検出回路（８）の出力信号中に交流信号として
混入する。そして、交流信号検出回路（１２）が前記ホ
ワイトノイズに起因する交流信号を検出して急速充電回
路（ｌ３）を駆動し、ミュート回路（７）が動作する危
険が生じる。本発明においては、その様な誤動作を防止
する為、受信信号の電界強度を示す信号、すなわち駆動
回路（９）から得られる直流信号のレベルを判別して、
交流信号検出回路（１２〉の動作を停止させる判別回路
（ｌ４）を設けている。この判別回路（１４）を設ける
ことにより、弱電界時（交流信号大、直流信号小）と中
強電界でマルチバス妨害発生時（交流信号大、直流信号
小）とを区別することが出来る．従って、ミュート回路
（７）は、弱電界時ソフトミュート回路として動作し、
マルチパス妨害時ハードミュート回路として動作する．
（ト）発明の効果
以上述べた如く、本発明に依れば、マルチバス妨害が発
生したときにノイズの低減を計ることが出来る。そして
、本発明においては、ソフトミュート回路に交流信号検
出回路及び急速充電回路を付加するだけで、それを達成
出来るので、構成が簡単である。By the way, when the electric field strength of the received signal is weak, the white noise level increases, and this white noise is mixed as an alternating current signal into the output signal of the detection circuit (8) that detects the electric field strength. Then, there is a risk that the AC signal detection circuit (12) detects the AC signal caused by the white noise and drives the quick charging circuit (13), causing the mute circuit (7) to operate. In the present invention, in order to prevent such malfunctions, the level of the signal indicating the electric field strength of the received signal, that is, the DC signal obtained from the drive circuit (9), is determined.
A discrimination circuit (l4) is provided to stop the operation of the AC signal detection circuit (12).By providing this discrimination circuit (14), it is possible to distinguish between weak electric field (large AC signal, small DC signal) and medium strong electric field. It is possible to distinguish between multi-bus interference (large AC signal, small DC signal).Therefore, the mute circuit (7) operates as a soft mute circuit in the case of a weak electric field.
Operates as a hard mute circuit when multipath interference occurs. (G) Effects of the Invention As described above, according to the present invention, it is possible to reduce noise when multi-bus interference occurs. In the present invention, this can be achieved by simply adding an AC signal detection circuit and a quick charging circuit to the soft mute circuit, so the configuration is simple.
第１図は、本発明の一実施例を示す回路図、及び第２図
は本発明の説明に供する為の特性図である。
（８〉・・・検出回路、 （９）・・・駆動回路、 （
１ｏ）・・・ミュート信号発生回路、 （１１）・・・
コンデンサ、（１２〉・・・交流信号検出回路、 〈１
３〉・・・急速充電回路、 （１４）・・・判別回路。FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a characteristic diagram for explaining the present invention. (8>...Detection circuit, (9)...Drive circuit, (
1o)...Mute signal generation circuit, (11)...
Capacitor, (12>... AC signal detection circuit, <1
3>...Quick charging circuit, (14)...Discrimination circuit.
Claims (3)
する駆動段と、 前記ミュート駆動信号に応じてソフトミュート信号を発
生するミュート信号発生手段と、 前記ソフトミュート信号に応じて信号路を ミュートするミュート手段と、 前記検出手段の出力信号中に含まれる所定レベル以上の
交流信号を検出する交流信号検出手段と、 該交流信号検出手段の出力信号に応じて前記ミュート手
段の動作を速める手段と から成り、マルチパス妨害時に、前記動作を速める手段
を作動させ、マルチパス妨害に起因するノイズを低減し
たことを特徴とするマルチパス妨害除去回路。(1) A detection means for detecting the electric field strength of a received signal, a drive stage for generating a mute drive signal according to the output signal of the detection means, and a mute signal generation for generating a soft mute signal according to the mute drive signal. means: muting means for muting a signal path in response to the soft mute signal; alternating current signal detecting means for detecting an alternating current signal of a predetermined level or higher included in the output signal of the detecting means; and means for accelerating the operation of the muting means in accordance with an output signal, and the multipath interference removal is characterized in that when multipath interference occurs, the means for accelerating the operation is activated to reduce noise caused by multipath interference. circuit.
前記ミュート手段の動作を速める手段は、前記コンデン
サを急速充電する急速充電回路から構成されることを特
徴とする請求項第１項記載のマルチパス妨害除去回路。(2) the mute signal generating means includes a capacitor;
2. The multipath interference removal circuit according to claim 1, wherein the means for accelerating the operation of the muting means comprises a quick charging circuit that rapidly charges the capacitor.
とを判別する判別手段を設け、該判別手段の出力信号に
より前記交流信号検出手段の動作を停止させることを特
徴とする請求項第１項記載のマルチパス妨害除去回路。(3) A discriminating means for discriminating whether the electric field strength of the received signal has fallen below a predetermined level is provided, and an output signal of the discriminating means causes the operation of the alternating current signal detecting means to be stopped. The multipath interference removal circuit described in .
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30024889A JP2865335B2 (en) | 1989-11-17 | 1989-11-17 | Multipath interference removal circuit |
| US07/612,392 US5204973A (en) | 1989-11-17 | 1990-11-13 | Receiver capable of quickly suppressing defective effect of multipath reflection interference |
| DE69028486T DE69028486T2 (en) | 1989-11-17 | 1990-11-16 | Receiver with the possibility of quickly suppressing the defective influence of the multipath reception interference |
| KR1019900018626A KR960000525B1 (en) | 1989-11-17 | 1990-11-16 | Receiver against multipass interference |
| EP90121973A EP0429021B1 (en) | 1989-11-17 | 1990-11-16 | A receiver capable of quickly suppressing defective effect of multipath reflection interference |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30024889A JP2865335B2 (en) | 1989-11-17 | 1989-11-17 | Multipath interference removal circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03160823A true JPH03160823A (en) | 1991-07-10 |
| JP2865335B2 JP2865335B2 (en) | 1999-03-08 |
Family
ID=17882496
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30024889A Expired - Fee Related JP2865335B2 (en) | 1989-11-17 | 1989-11-17 | Multipath interference removal circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2865335B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007324692A (en) * | 2006-05-30 | 2007-12-13 | Pioneer Electronic Corp | Mute circuit |
-
1989
- 1989-11-17 JP JP30024889A patent/JP2865335B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007324692A (en) * | 2006-05-30 | 2007-12-13 | Pioneer Electronic Corp | Mute circuit |
| JP4683558B2 (en) * | 2006-05-30 | 2011-05-18 | パイオニア株式会社 | Mute circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2865335B2 (en) | 1999-03-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |