JPS6314513Y2 - - Google Patents
Info
- Publication number
- JPS6314513Y2 JPS6314513Y2 JP5461281U JP5461281U JPS6314513Y2 JP S6314513 Y2 JPS6314513 Y2 JP S6314513Y2 JP 5461281 U JP5461281 U JP 5461281U JP 5461281 U JP5461281 U JP 5461281U JP S6314513 Y2 JPS6314513 Y2 JP S6314513Y2
- Authority
- JP
- Japan
- Prior art keywords
- noise
- circuit
- volume
- detection circuit
- multipath noise
- 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.)
- Expired
Links
- 238000001514 detection method Methods 0.000 claims description 24
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 claims description 13
- 230000005236 sound signal Effects 0.000 description 7
- 230000002238 attenuated effect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
Landscapes
- Noise Elimination (AREA)
Description
【考案の詳細な説明】
本考案は、FM受信回路で受信した受信波から
検出したマルチパス雑音の大きさに応じて、音声
周波数の高域を減衰させる装置において、音声周
波数の高域を減衰させた場合とさせない場合とで
音量が変わらないようにして不快感をなくすよう
にしたマルチパス雑音除去装置に関する。[Detailed description of the invention] The present invention is a device that attenuates the high range of audio frequencies according to the magnitude of multipath noise detected from the received waves received by the FM receiving circuit. This invention relates to a multipath noise removal device that eliminates discomfort by keeping the volume the same whether the noise is turned on or not.
通常、FM電波を受信する場所によつては、送
信アンテナからの直接波以外に、山・建物等で反
射して直接波と位相のずれた反射波が存在する。 Normally, depending on the location where FM radio waves are received, in addition to the direct waves from the transmitting antenna, there are reflected waves that are reflected from mountains, buildings, etc. and are out of phase with the direct waves.
これはいわゆるマルチパスといわれるものであ
る。このマルチパスが発生する場所でFM電波を
受信すると、位相及び振幅に干渉を生じた信号が
受信アンテナに誘起され、この復調再生音に歪や
雑音が含まれ聞き苦しい音になる。このマルチパ
ス雑音を除去する方法として、従来第１図に示す
ように、検波回路５と低周波増幅回路６との間に
音声信号中の高域成分を減衰させる（ハイカツト
する）フイルタ８を設け、また中間周波数増幅器
４の後に、マルチパス雑音を検出しているときに
出力するマルチパス雑音検出回路９を設けてあ
る。そして、マルチパス雑音検出回路９が出力し
ていないときには、フイルタ８が作動せずに音声
信号中の高域成分の減衰がなく、マルチパス雑音
検出回路９が出力しているときには、フイルタ８
が作動してその高域成分が減衰される。このよう
にマルチパス雑音が発生しているときに、音声信
号の高域成分を減衰して、聴感上歪が目立たない
ようにしている。また高域における減衰のない場
合を第２図に実線で示し、高域における減衰のあ
る場合を同図に破線で示してある。なお、１は受
信アンテナ、２は高周波増幅器、３は周波数変換
器、７はスピーカである。 This is what is called multipath. When FM radio waves are received in a place where this multipath occurs, signals with phase and amplitude interference are induced in the receiving antenna, and the demodulated reproduced sound contains distortion and noise, making it difficult to hear. As a method of removing this multipath noise, conventionally, as shown in FIG. 1, a filter 8 is provided between a detection circuit 5 and a low frequency amplifier circuit 6 to attenuate (high cut) high frequency components in the audio signal. Further, after the intermediate frequency amplifier 4, a multipath noise detection circuit 9 is provided which outputs an output when detecting multipath noise. When the multipath noise detection circuit 9 is not outputting, the filter 8 is not activated and there is no attenuation of high-frequency components in the audio signal, and when the multipath noise detection circuit 9 is outputting, the filter 8 is not activated.
is activated to attenuate its high frequency components. When multipath noise occurs in this way, the high-frequency components of the audio signal are attenuated to make the distortion less noticeable to the auditory sense. Further, the case in which there is no attenuation in the high range is shown by a solid line in FIG. 2, and the case in which there is attenuation in the high range is shown in the same figure by a broken line. Note that 1 is a receiving antenna, 2 is a high frequency amplifier, 3 is a frequency converter, and 7 is a speaker.
このような方式を用いると、マルチパス雑音の
発生に応じて雑音除去が行われ、聴取者に雑音に
よる不快感を与える事がない。しかし、音量につ
いては、上記従来例は、第２図に示すように、マ
ルチパス雑音が発生しているときに高域が減衰
し、しかもマルチパス雑音の充分な軽減感を得る
ためには減衰量を多くするので、マルチパス雑音
が発生してないときよりも全体の音量が低下す
る。したがつてたとえばFM受信機を搭載した車
両の中で同一放送内容を受信する場合、マルチパ
ス雑音の生じる地域と生じない地域とを交互に通
過すると、再声音量に変動が生じて聴取者が音量
変化による不快感を感じるという問題がある。 When such a method is used, noise is removed according to the occurrence of multipath noise, and the listener is not made to feel uncomfortable due to the noise. However, regarding the volume, as shown in Figure 2, the conventional example above attenuates the high frequency range when multipath noise is occurring, and it is difficult to attenuate in order to obtain a sufficient feeling of reducing multipath noise. Since the amount is increased, the overall volume will be lower than when multipath noise is not occurring. Therefore, for example, when receiving the same broadcast content in a vehicle equipped with an FM receiver, if the listener passes through areas where multipath noise occurs and areas where it does not occur, the reproduced voice volume will fluctuate and the listener may There is a problem in that people feel discomfort due to changes in volume.
そこで、本考案は、受信回路で受信した受信波
に基きマルチパス雑音を検出する雑音検出回路
と、該回路での検出に応じて音声周波数の高域を
減衰する高域減衰回路とを有するFM受信装置に
おいて、音量を一定量減少させる音量減少手段
と、前記雑音検出回路が雑音を検出していない時
には該手段を作動し、雑音を検出している時には
非作動にする音量減少制御手段とを有し、音声周
波数の高域を減衰させた場合とさせない場合とで
音量が変化しないようにしたものである。 Therefore, the present invention provides an FM system that includes a noise detection circuit that detects multipath noise based on the received waves received by the receiving circuit, and a high-frequency attenuation circuit that attenuates the high-frequency range of audio frequencies according to the detection by the circuit. The receiving device includes a volume reduction means for reducing the volume by a certain amount, and a volume reduction control means that operates the means when the noise detection circuit does not detect noise and deactivates it when the noise detection circuit detects noise. The sound volume does not change depending on whether the high frequency range of the audio frequency is attenuated or not.
以下、添付図面に示す実施例にづいて本考案を
詳述する。なお、同一部材については同一符号を
付してある。図中、インバータ１０はマルチパス
雑音検出回路９の出力を反転させるのであり、音
量減少回路１１はマルチパス雑音が生じてないと
きに、検波出力を全域に亘つてほぼ均等に減衰さ
せて、再生音量を減少させる回路である。なお、
マルチパス雑音検出回路９は、たとえば中間周波
信号の振幅成分を検出するAM検波回路と、シユ
ミツト・トリガ回路とで構成されている。 Hereinafter, the present invention will be described in detail with reference to embodiments shown in the accompanying drawings. Note that the same members are given the same reference numerals. In the figure, an inverter 10 inverts the output of the multipath noise detection circuit 9, and a volume reduction circuit 11 attenuates the detection output almost uniformly over the entire area when no multipath noise occurs, and reproduces the output. This is a circuit that reduces the volume. In addition,
The multipath noise detection circuit 9 includes, for example, an AM detection circuit that detects the amplitude component of an intermediate frequency signal and a Schmitt trigger circuit.
次にこの実施例の動作について説明する。まず
マルチパス雑音が生じている場合について説明す
る。この場合、マルチパス雑音検出回路９が出力
するので、フイルタ８中のトランジスタ８ａがオ
ンし、音声信号中の高域成分が減衰するために、
聴感上歪が目立たない再生音になり、これととも
にその減衰分に応じた音量が低下する。一方、イ
ンバータ１０がマルチパス雑音検出回路９の出力
を反転させるので、インバータ１０は出力せず、
したがつてトランジスタ１１ａがオフであるか
ら、音量減少回路１１における信号の減衰はほと
んどない。 Next, the operation of this embodiment will be explained. First, a case where multipath noise occurs will be explained. In this case, since the multipath noise detection circuit 9 outputs, the transistor 8a in the filter 8 is turned on, and the high frequency components in the audio signal are attenuated.
The reproduced sound has less noticeable distortion to the auditory sense, and at the same time, the volume decreases in proportion to the attenuation. On the other hand, since the inverter 10 inverts the output of the multipath noise detection circuit 9, the inverter 10 does not output,
Therefore, since the transistor 11a is off, there is almost no attenuation of the signal in the volume reduction circuit 11.
次にマルチパス雑音が生じてない場合、マルチ
パス雑音検出回路９が出力しないので、トランジ
スタ８ａがオフし、音声信号中の高域成分の減衰
がない。この場合、インバータ１０が出力するの
で、トランジスタ１１ａがオンし、低域から高域
に亘つて均等に音声信号の一部がアースに流れ、
このアースに流れた分に応じてスピーカ７で発生
する再生音量が低下する。ここで、音量減少回路
１１が作動することにより再生音量の低下量とフ
イルタ８が作動することによる再生音量の低下量
とが同じになるようにフイルタ８及び音量減少回
路１１を構成する回路素子それぞれの定数が設定
されている。 Next, when multipath noise is not occurring, the multipath noise detection circuit 9 does not output any output, so the transistor 8a is turned off, and there is no attenuation of high frequency components in the audio signal. In this case, since the inverter 10 outputs, the transistor 11a is turned on, and a part of the audio signal flows evenly from the low frequency range to the high frequency range to the ground.
The playback volume generated by the speaker 7 decreases in accordance with the amount flowing to the ground. Here, each of the circuit elements constituting the filter 8 and the volume reduction circuit 11 is configured so that the amount of reduction in the playback volume due to the operation of the volume reduction circuit 11 is the same as the amount of reduction in the reproduction volume due to the operation of the filter 8. constants are set.
したがつてマルチパス雑音の生じていない地域
と生じている地域とを交互に通過しても、その間
における再生音量の変化がない。 Therefore, even if the signal alternately passes through areas where multipath noise does not occur and areas where it occurs, there is no change in the playback volume between them.
本考案の実施例として、次の態様も考えられ
る。音量減少回路１１の代わりに、検波回路５と
フイルタ８との間のインピーダンスを、マルチパ
ス雑音の有無によつて変化させてもよく、音量減
少回路１１またはフイルタ８を音声信号系の別の
場所に設けてもよく、また検出回路９を検波回路
５の後に設けてもよい。更に第３図示実施例で
は、マルチパス雑音が少しでも発生すれば、その
量に関係なく、フイルタ８によつて常に同量の減
衰を行なつている。しかし、マルチパス雑音の量
に応じて、フイルタ８による減衰量を制御し、し
かもマルチパス雑音の有無に関係なく再生音量を
一定に保つようにしてもよい。 The following aspects can also be considered as embodiments of the present invention. Instead of the volume reduction circuit 11, the impedance between the detection circuit 5 and the filter 8 may be changed depending on the presence or absence of multipath noise, and the volume reduction circuit 11 or the filter 8 may be installed at another location in the audio signal system. Alternatively, the detection circuit 9 may be provided after the detection circuit 5. Furthermore, in the third illustrated embodiment, if even a small amount of multipath noise occurs, the same amount of attenuation is always performed by the filter 8, regardless of the amount. However, the amount of attenuation by the filter 8 may be controlled depending on the amount of multipath noise, and the reproduction volume may be kept constant regardless of the presence or absence of multipath noise.
上記の通り本考案は、マルチパス雑音が雑音検
出回路によつて検出されている場合には、音量減
少手段を非作動とし、一方、マルチパス雑音が検
出されていない場合には、音量減少手段を作動さ
せて音量を一定量減少させるようにしたので、マ
ルチパス雑音の有無に拘らず音量を一定に保つこ
とができるという効果を奏する。 As described above, the present invention deactivates the volume reduction means when multipath noise is detected by the noise detection circuit, and on the other hand, when multipath noise is not detected, the volume reduction means Since the sound volume is reduced by a certain amount by operating the sound volume, the sound volume can be kept constant regardless of the presence or absence of multipath noise.
第１図は従来のマルチパス雑音除去回路を示す
図、第２図は従来例におけるフイルタ８の出力レ
ベルを示す図、第３図は本考案の一実施例を示す
図である。
８……フイルタ、９……マルチパス雑音検出回
路、１０……インバータ、１１……音量減少回
路。
FIG. 1 is a diagram showing a conventional multipath noise removal circuit, FIG. 2 is a diagram showing the output level of a filter 8 in the conventional example, and FIG. 3 is a diagram showing an embodiment of the present invention. 8... Filter, 9... Multipath noise detection circuit, 10... Inverter, 11... Volume reduction circuit.
Claims (1)
音を検出する雑音検出回路と、該回路での検出に
応じて音声周波数の高域を減衰する高域減衰回路
とを有するFM受信装置において、音量を一定量
減少させる音量減少手段と、前記雑音検出回路が
雑音を検出していない時には該手段を作動し、雑
音を検出している時には非作動にする音量減少制
御手段とを有することを特徴とするFM受信機の
マルチパス雑音除去装置。 An FM receiving device that includes a noise detection circuit that detects multipath noise based on received waves received by the receiving circuit, and a high-frequency attenuation circuit that attenuates the high frequency range of audio frequencies according to the detection by the circuit. It is characterized by comprising a volume reduction means for reducing the volume by a certain amount, and a volume reduction control means that operates the means when the noise detection circuit does not detect noise and deactivates it when the noise detection circuit detects noise. Multipath noise removal device for FM receiver.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5461281U JPS6314513Y2 (en) | 1981-04-17 | 1981-04-17 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5461281U JPS6314513Y2 (en) | 1981-04-17 | 1981-04-17 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57168339U JPS57168339U (en) | 1982-10-23 |
| JPS6314513Y2 true JPS6314513Y2 (en) | 1988-04-22 |
Family
ID=29851206
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5461281U Expired JPS6314513Y2 (en) | 1981-04-17 | 1981-04-17 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6314513Y2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6077138U (en) * | 1983-10-31 | 1985-05-29 | パイオニア株式会社 | noise suppression device |
-
1981
- 1981-04-17 JP JP5461281U patent/JPS6314513Y2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57168339U (en) | 1982-10-23 |
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