JPS6331316A - Fm noise elimination device - Google Patents
Fm noise elimination deviceInfo
- Publication number
- JPS6331316A JPS6331316A JP17591286A JP17591286A JPS6331316A JP S6331316 A JPS6331316 A JP S6331316A JP 17591286 A JP17591286 A JP 17591286A JP 17591286 A JP17591286 A JP 17591286A JP S6331316 A JPS6331316 A JP S6331316A
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- output
- signal
- pulse
- control
- 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
- 230000008030 elimination Effects 0.000 title 1
- 238000003379 elimination reaction Methods 0.000 title 1
- 238000001514 detection method Methods 0.000 claims abstract description 10
- 230000015572 biosynthetic process Effects 0.000 claims description 7
- 238000003786 synthesis reaction Methods 0.000 claims description 7
- 230000006866 deterioration Effects 0.000 abstract description 2
- 230000000737 periodic effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 7
- 230000001629 suppression Effects 0.000 description 5
- 230000005684 electric field Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000007257 malfunction Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 241000270666 Testudines Species 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 230000000630 rising effect 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ＦＭ受信機の雑音、特にマルチパス妨害による
雑音を除去するようにしたＦＭ雑音除去装置に関するも
のである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an FM noise removal device for removing noise in an FM receiver, particularly noise caused by multipath interference.
従来の技術
近年コンパクトディスク等の車載用オーディオ機器の性
能が高まるにつれて、車載用ＦＭ受信機にもこれらに見
合う高品質が要求され、特にＦＭ受信時におけるマルチ
パス妨害による雑音の除去あるいは抑圧が重要視されて
いる。Conventional technology In recent years, as the performance of in-vehicle audio equipment such as compact discs has improved, in-vehicle FM receivers are required to have high quality to match these demands, and it is especially important to remove or suppress noise caused by multipath interference during FM reception. being watched.
これらの背景から従来の技術として、例えば実開昭６０
−２２０４４号公報に記載の「ＦＭ受信機マルチパスノ
イズ抑圧装置」等がある。From these backgrounds, as a conventional technique, for example,
There are examples such as "FM receiver multipath noise suppression device" described in Publication No.-22044.
以下、図面を参照しながら、上述したような従来のＦＭ
受信機マルチパス抑圧装置について説明を行なう。Below, with reference to the drawings, the conventional FM as described above
The receiver multipath suppression device will be explained.
第７図は従来例の構成を示すものである。FIG. 7 shows the configuration of a conventional example.
第７図において、１はＦＭ中間周波信号を印加する入力
端子、２はＦＭ復調回路、３はキャリア振幅検波回路、
１６は直流変換回路、１７は雑音抑圧回路、１８はマル
チプレックス復調回路、１９゜２０は各々左右の復調出
力端子である。In FIG. 7, 1 is an input terminal for applying an FM intermediate frequency signal, 2 is an FM demodulation circuit, 3 is a carrier amplitude detection circuit,
16 is a DC conversion circuit, 17 is a noise suppression circuit, 18 is a multiplex demodulation circuit, and 19° and 20 are left and right demodulation output terminals, respectively.
以上の従来例の構成の動作について説明する。The operation of the above conventional configuration will be explained.
ＦＭ受信時においてマルチパス妨害を受けると、ＦＭキ
ャリアがマルチパス波によって振幅変動を生じるため、
キャリア振幅検波回路３でその振幅変動成分を抽出し、
その出力を直流変換回路１６によって平滑化し、その出
力を制御信号として、ＦＭ復調回路２の出力に接続され
た雑音抑圧回路１了によって、ミューティング、あるい
は高域遮断等の制御を行なうものである。When receiving multipath interference during FM reception, the FM carrier causes amplitude fluctuations due to the multipath waves.
The carrier amplitude detection circuit 3 extracts the amplitude fluctuation component,
The output is smoothed by a DC conversion circuit 16, and the output is used as a control signal to control muting or high frequency cutoff by a noise suppression circuit 1 connected to the output of the FM demodulation circuit 2. .
さらにマルチプレックス復調回路１８を制御してステレ
オ分離度を低下させて雑音の抑圧を行なうものである。Furthermore, the multiplex demodulation circuit 18 is controlled to lower the degree of stereo separation and suppress noise.
発明が解決しようとする問題点
しかしながら、前記のような構成ではマルチパス妨害の
検出の方法がキャリアの振幅変動成分を平滑して直流の
制御信号としているために、電界強度が変動した時も検
出電圧が変化し基本的に誤動作する要因となっている。Problems to be Solved by the Invention However, in the above configuration, the method for detecting multipath interference smoothes the amplitude fluctuation component of the carrier and uses it as a DC control signal, so it is difficult to detect even when the electric field strength fluctuates. The voltage changes, which basically causes malfunctions.
また雑音抑圧回路１７の動作によって、ミューティング
は雑音とともに信号のレベルも低下してしまうため、情
報が欠落し、聴きとりにくくなったり、高域遮断につい
ても信号の品質が劣化し、忠実度が低下する。また、ス
テレオ分離度を制御する方法はやはり本来のステレオ感
が得られなくなるという問題点を有していた。Furthermore, due to the operation of the noise suppression circuit 17, muting causes both noise and the signal level to drop, resulting in information being lost and becoming difficult to hear.High-frequency cutoff also degrades signal quality and impairs fidelity. descend. Furthermore, the method of controlling the degree of stereo separation still has the problem that the original stereo feeling cannot be obtained.
本発明は上記問題点に鑑み、電界変動の変化に対して誤
動作せず、またＦＭ復調信号の品質を劣化させずにマル
チパス妨害の影響を取り除くことのできるＦＭ雑音除去
装置を提供するものである。In view of the above-mentioned problems, the present invention provides an FM noise removal device that can eliminate the effects of multipath interference without malfunctioning due to changes in electric field fluctuations and without degrading the quality of FM demodulated signals. be.
問題点を解決するための手段
この目的を達成するために本発明のＦＭ雑音除去装置は
、ＦＭ信号のキャリアの振幅を検波する回路と、この回
路の出力に接続された高域通過フィルタと、このフィル
タの出力を入力して基準電圧と比較する比較回路と、こ
の比較回路の出力を入力して制御信号を出力する制御回
路と、雑音を含むＦＭ復調信号を入力して前記制御信号
によって雑音の生じた区間の信号を補間する回路とを備
えだ構成となっている。Means for Solving the Problems To achieve this object, the FM noise removal device of the present invention includes a circuit for detecting the amplitude of the carrier of an FM signal, a high-pass filter connected to the output of this circuit, a comparison circuit that inputs the output of this filter and compares it with a reference voltage; a control circuit that inputs the output of this comparison circuit and outputs a control signal; and a control circuit that inputs an FM demodulated signal containing noise and generates noise by the control signal. The configuration includes a circuit for interpolating the signal in the section where the .
作用
この構成によってまず高域通過フィルタにより電界変動
等の低い周波数成分が除かれるため、誤動作が生じなく
なる。Effect: With this configuration, first, low frequency components such as electric field fluctuations are removed by the high-pass filter, thereby preventing malfunctions.
また振幅変動成分の高域成分を抽出するため、マルチパ
ス妨害による時間間隔の短い雑音の個々に対応した検出
が可能となる。Furthermore, since the high-frequency component of the amplitude fluctuation component is extracted, it is possible to individually detect noise with short time intervals due to multipath interference.
一方前記フィルタの影響によって、このフィルタの出力
から得た比較パルスの幅と雑音の発生区間の幅に差が生
じるが、制御回路によって比較パルスの幅に応じたパル
ス幅を付加して雑音の生じた区間に一致させ、補間回路
によって補間信号を作シ、雑音のみを除去することによ
り、ＦＭ復調信号の品質の低下を防ぐこととなる。On the other hand, due to the influence of the filter, there is a difference between the width of the comparison pulse obtained from the output of this filter and the width of the noise generation section. The interpolation signal is generated by an interpolation circuit, and only the noise is removed, thereby preventing the quality of the FM demodulated signal from deteriorating.
実施例
以下本発明の一実施例について図面を参照しながら説明
する。第１図は本発明の一実施例におけるＦＭ雑音除去
装置の構成を示すものである。EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an FM noise removal device in an embodiment of the present invention.
第１図において、１はＦＭ中間周波信号が印加される入
力端子、２はＦＭ復調回路、３はキャリア振幅検波回路
、４はキャリア振幅検波回路３の出力を入力とする高域
通過フィルタ、５は高域通過フィルタ４の出力を入力と
し、基準電圧との比較を行なう比較回路、６は比較回路
５の出力を入力とし、信号補間のための制御信号を出力
する制御回路、７はＦＭ復調回路２の出力に接続され、
制御回路６の制御信号によシ復調信号を補間する信号補
間回路、８は出力端子である。In FIG. 1, 1 is an input terminal to which an FM intermediate frequency signal is applied, 2 is an FM demodulation circuit, 3 is a carrier amplitude detection circuit, 4 is a high-pass filter that receives the output of the carrier amplitude detection circuit 3, and 5 6 is a comparison circuit that receives the output of the high-pass filter 4 and compares it with a reference voltage; 6 is a control circuit that receives the output of the comparison circuit 5 and outputs a control signal for signal interpolation; 7 is an FM demodulation circuit. connected to the output of circuit 2,
A signal interpolation circuit interpolates the demodulated signal based on the control signal of the control circuit 6, and 8 is an output terminal.
以上のように構成された実施例について、以下その動作
について各部の信号波形図を参照しながら説明する。The operation of the embodiment configured as above will be described below with reference to signal waveform diagrams of each part.
第２図のａ −ｆは第１図の各部の信号波形図である。A to f in FIG. 2 are signal waveform diagrams of each part in FIG. 1.
まず第１図の入力端子１にはマルチパス訪客による干渉
を受けた中間周波信号ａが入力され、振幅検波回路３で
中間周波信号ａのエンベロープが検波され、さらに高域
通過フィルタ４で電界強度変動成分等のマルチパス妨害
以外の変動成分が除去されて信号すとなり比較回路６に
入力される。First, an intermediate frequency signal a that has been interfered with by a multipath visitor is input to the input terminal 1 in FIG. Fluctuation components other than multipath interference, such as fluctuation components, are removed and the signal is input to the comparison circuit 6.
比較回路６は信号６の波形中に示す基準電圧と比較し、
パルスＣを出力する。制御回路６はパルスＣの波形を波
形成形して制御信号ｄを出力する。Comparison circuit 6 compares the signal 6 with a reference voltage shown in the waveform,
Outputs pulse C. The control circuit 6 shapes the waveform of the pulse C and outputs a control signal d.
一方、第１図のＦＭ復調回路２の復調出力は波形θとな
り、部分的に雑音が含まれている。On the other hand, the demodulated output of the FM demodulation circuit 2 in FIG. 1 has a waveform θ, which partially contains noise.
ここで制御信号ｄのパルス幅はこの雑音区間を含むよう
に制御回路６によって広げられており、信号補間回路７
によって例えば直線で補間された場合、信号での波形と
なり雑音が除去されていることがわかる。Here, the pulse width of the control signal d is widened by the control circuit 6 to include this noise section, and the signal interpolation circuit 7
For example, when linear interpolation is performed, it becomes a signal waveform, and it can be seen that noise is removed.
ここで変調度及び変調周波数が高くなった場合の各部の
信号波形図を第３図ａ −ｆ’に示す。第３図において
、第２図と同様にして亀は中間周波数信号、ｂは高域通
過フィルタ４の出力信号、Ｃは比較回路６の出力信号、
ｄは制御回路６の出力信号、ｅはＦＭ復調回路２の出力
信号、ｆは信号補間回路の出力信号である。第２図の変
調度及び変調周波数が低い場合に比べて比較回路５の出
力信号のパルス幅が小さくなり、制御回路６ではパルス
幅の拡大は行なわれていないことがわかる。もし、第２
図に示す制御出力の信号ｄの様にパルス幅を拡大すると
、第３図の制御出力の信号ｄのパルスは連続し、非常に
広いパルス幅となってしまい、補間回路の出力と実際の
変調波形との誤差が大きくなってしまう。FIG. 3 a-f' shows signal waveform diagrams of various parts when the modulation degree and modulation frequency are increased. In FIG. 3, similarly to FIG. 2, turtle is an intermediate frequency signal, b is the output signal of the high-pass filter 4, C is the output signal of the comparator circuit 6,
d is the output signal of the control circuit 6, e is the output signal of the FM demodulation circuit 2, and f is the output signal of the signal interpolation circuit. It can be seen that the pulse width of the output signal of the comparator circuit 5 is smaller than that in the case where the modulation degree and modulation frequency are low in FIG. 2, and the pulse width is not expanded in the control circuit 6. If the second
If the pulse width is expanded like the control output signal d shown in the figure, the pulses of the control output signal d in Figure 3 will be continuous and have a very wide pulse width, and the output of the interpolation circuit and the actual modulation will be The error with the waveform becomes large.
従って制御回路６は比較回路４の出力信号のパルス幅が
基準の長さより小さい場合はパルス幅を拡大せず、逆に
広い場合には、高域通過フィルタ４の応答による影響を
補正し、雑音区間に制御パルス幅を一致させるためにパ
ルス幅を広げる動作をする。Therefore, if the pulse width of the output signal of the comparator circuit 4 is smaller than the reference length, the control circuit 6 does not expand the pulse width, but if it is wider than the reference length, the control circuit 6 corrects the influence of the response of the high-pass filter 4 and eliminates noise. The pulse width is expanded to match the control pulse width to the interval.
以下この制御回路についての実施例を第４図を参照しな
がら説明する。An embodiment of this control circuit will be described below with reference to FIG.
第４図において、９は比較回路６の出力信号を印加する
入力端子、１０はパルス合成回路、１１は入力端子９に
接続された付加パルス発生回路、１２は入力端子９に接
続された基準パルス発生回路、１３は入力端子９と基準
パルス発生器１２の出力に接続された判定回路、１４は
付加パルス発生回路の出力と判定回路１３の出力に接続
された選択回路で、パルス合成回路１ｏには入力端子９
と選択回路１４の出力が接続され、１５の出力端子に出
力する。In FIG. 4, 9 is an input terminal to which the output signal of the comparison circuit 6 is applied, 10 is a pulse synthesis circuit, 11 is an additional pulse generation circuit connected to the input terminal 9, and 12 is a reference pulse connected to the input terminal 9. 13 is a determination circuit connected to the input terminal 9 and the output of the reference pulse generator 12; 14 is a selection circuit connected to the output of the additional pulse generation circuit and the output of the determination circuit 13; is input terminal 9
and the output of the selection circuit 14 are connected and output to the output terminal 15.
次にこの制御回路の動作について、第６図及び第６図の
タイミングチャートを参照しながら説明する。Next, the operation of this control circuit will be explained with reference to FIG. 6 and the timing chart shown in FIG.
第５図は比較回路Ｓの出力信号のパルス幅が広い場合、
第６図はパルス幅が狭い場合の各部の信号波形を示した
ものである。Figure 5 shows that when the pulse width of the output signal of the comparator circuit S is wide,
FIG. 6 shows signal waveforms at various parts when the pulse width is narrow.
まず第６図において、パルス幅が広い比較信号ａが入力
端子９に印加された場合、基準パルス発生回路１２の出
力には信号波形すが得られる。次に判定回路１３は基準
パルス発生回路１２の信号すの立下りで入力信号９をサ
ンプリングして保持し、前記信号すの立上シでリセット
する。すなわち出力信号Ｃが得られる。一方、付加パル
ス発生回路１１は入力信号への立下りでセットされ、−
定時間保持し、出力ｄが得られる。ここで選択回路１４
は判定回路の出力Ｃが論理Ｊｌ＋の場合に付加パルス発
生回路１１の出力ｄを選択してパルス合成回路１０に入
力する。ここでパルス合成回路１０は入力信号ａと選択
回路１４の出力とを合成して信号ｅを出力する。First, in FIG. 6, when a comparison signal a having a wide pulse width is applied to the input terminal 9, a signal waveform is obtained at the output of the reference pulse generation circuit 12. Next, the determination circuit 13 samples and holds the input signal 9 at the falling edge of the signal S of the reference pulse generating circuit 12, and resets it at the rising edge of the signal S. That is, an output signal C is obtained. On the other hand, the additional pulse generation circuit 11 is set at the falling edge of the input signal, and -
It is held for a fixed time and output d is obtained. Here, the selection circuit 14
selects the output d of the additional pulse generation circuit 11 and inputs it to the pulse synthesis circuit 10 when the output C of the determination circuit is the logic Jl+. Here, the pulse synthesis circuit 10 synthesizes the input signal a and the output of the selection circuit 14 and outputs a signal e.
次に第６図において、パルス幅が狭い比較信号亀が入力
された場合、判定回路１３の出力信号は波形Ｃとなり、
選択回路１４により付加回路の出力Ｕはパルス合成回路
１０には入力されない。従ってパルス合成回路１０の出
力信号Ｖは入力信号ｒと同一となる。以上の様に本実施
例によれば、ＦＭ復調波に含まれる雑音の区間の長さに
適応して制御パルス幅を切り換えることにより、正確な
信号補間が可能となる。Next, in FIG. 6, when a comparison signal with a narrow pulse width is input, the output signal of the determination circuit 13 becomes waveform C,
The selection circuit 14 prevents the output U of the additional circuit from being input to the pulse synthesis circuit 10. Therefore, the output signal V of the pulse synthesis circuit 10 is the same as the input signal r. As described above, according to this embodiment, accurate signal interpolation is possible by switching the control pulse width in accordance with the length of the noise section included in the FM demodulated wave.
発明の効果
本発明は、ＦＭキャリア振幅検波出力の高域成分から信
号補間のための制御出力を検出しているために、電界変
動等によるマルチパス妨害以外の変動に対して誤動作を
防ぐことができ、さらに検出出力信号のパルス幅に対応
して制御パルス幅を切換えることによって個々の雑音の
幅に応じた信号補間を行なうことによシ復調信号の品質
の劣化を最小にしてマルチパス訪客雑音を取り除くこと
ができるＦＭ雑音除去装置が実現できるものである。Effects of the Invention Since the present invention detects the control output for signal interpolation from the high-frequency component of the FM carrier amplitude detection output, it is possible to prevent malfunctions due to fluctuations other than multipath interference due to electric field fluctuations, etc. Furthermore, by switching the control pulse width in accordance with the pulse width of the detection output signal, signal interpolation is performed according to the width of each noise, minimizing deterioration in the quality of the demodulated signal and eliminating multipath visitor noise. This makes it possible to realize an FM noise removal device that can remove .
第１図は本発明の一実施例におけるＦＭ雑音除去装置の
構成を示すブロック図、第２図は本実施例において、マ
ルチパス妨害を受けたＦＭ中間周波信号を入力したとき
の変調度、変調周波数ともに低い場合の各部の波形図、
第３図は同変調度。
変調周波数ともに高い場合の各部の波形図、第４図は本
実施例における制御回路のブロック図、第５図、第６図
は本実施例における制御回路の各部の波形を示すタイミ
ングチャート、第７図は従来のＦＭ雑音除去装置の構成
を示すブロック図である。
１・・・・・・入力端子、２・・・・・・ＦＭ復調回路
、３・・・・・・キャリア振幅検波回路、４・・・・・
・高域通過フィルタ、５・・・・・・比較回路、６・・
・・・・制御回路。
代理人の氏名 弁理士 中 尾 敏 男 ほか１名第
２ 図
洸
第３図
第５図 第６図Fig. 1 is a block diagram showing the configuration of an FM noise removal device in an embodiment of the present invention, and Fig. 2 shows the modulation depth and modulation when an FM intermediate frequency signal subjected to multipath interference is input in this embodiment. Waveform diagram of each part when both frequencies are low,
Figure 3 shows the same modulation degree. FIG. 4 is a block diagram of the control circuit in this embodiment. FIGS. 5 and 6 are timing charts showing waveforms in each section of the control circuit in this embodiment. The figure is a block diagram showing the configuration of a conventional FM noise removal device. 1...Input terminal, 2...FM demodulation circuit, 3...Carrier amplitude detection circuit, 4...
・High-pass filter, 5... Comparison circuit, 6...
...control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person
2 Figure 3 Figure 5 Figure 6
Claims (2)
、この検波回路の出力に接続された高域通過フィルタと
、この高域通過フィルタの出力を入力して基準電圧と比
較する比較回路と、この比較回路の出力を入力して制御
信号を出力する制御回路と、雑音を含むＦＭ復調信号を
入力して前記制御信号によって雑音の生じた区間の信号
を補間する回路とを備えた事を特徴とするＦＭ雑音除去
装置。(1) A detection circuit that detects the amplitude of the carrier of the FM signal, a high-pass filter connected to the output of this detection circuit, and a comparison circuit that inputs the output of this high-pass filter and compares it with a reference voltage. , a control circuit that inputs the output of this comparison circuit and outputs a control signal, and a circuit that inputs an FM demodulated signal containing noise and interpolates the signal in the section where the noise occurs using the control signal. Features of FM noise removal device.
合成回路と、付加パルス発生回路と、基準パルス発生回
路とを備え、この基準パルス発生回路の出力と前記比較
回路の出力とを入力して論理演算を行なう判定回路と、
この判定回路の出力により前記付加パルス発生回路の出
力と前記パルス合成回路の入力との接続を制御する選択
回路を備え、前記比較回路の出力のパルス幅が基準パル
ス幅より長い場合に前記比較回路の出力の後端にこの出
力のパルス幅以下の長さのパルスを付加して、パルス幅
を拡大した制御信号を出力することを特徴とする特許請
求の範囲第１項記載のＦＭ雑音除去装置。(2) The control circuit includes a pulse synthesis circuit that inputs the output of the comparison circuit, an additional pulse generation circuit, and a reference pulse generation circuit, which inputs the output of the reference pulse generation circuit and the output of the comparison circuit. a determination circuit that performs logical operations;
a selection circuit that controls connection between the output of the additional pulse generation circuit and the input of the pulse synthesis circuit based on the output of the determination circuit; FM noise removal device according to claim 1, characterized in that a pulse having a length equal to or less than the pulse width of this output is added to the rear end of the output of the output to output a control signal with an expanded pulse width. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17591286A JPS6331316A (en) | 1986-07-25 | 1986-07-25 | Fm noise elimination device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17591286A JPS6331316A (en) | 1986-07-25 | 1986-07-25 | Fm noise elimination device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6331316A true JPS6331316A (en) | 1988-02-10 |
Family
ID=16004417
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17591286A Pending JPS6331316A (en) | 1986-07-25 | 1986-07-25 | Fm noise elimination device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6331316A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007069445A1 (en) * | 2005-12-14 | 2007-06-21 | Pioneer Corporation | Multi-path noise detecting device and multi-path noise eliminating device |
-
1986
- 1986-07-25 JP JP17591286A patent/JPS6331316A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007069445A1 (en) * | 2005-12-14 | 2007-06-21 | Pioneer Corporation | Multi-path noise detecting device and multi-path noise eliminating device |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6690805B1 (en) | Audio signal noise reduction system | |
| EP0253902B1 (en) | Noise reduction apparatus and method | |
| EP1111802B1 (en) | Impulse noise reducer detecting impulse noise from an audio signal | |
| EP1120919B1 (en) | Multipath noise reducer, audio output circuit, and FM receiver | |
| US6826392B2 (en) | Multipath noise reduction method, multipath noise reducer, and FM receiver | |
| EP0543396A1 (en) | Frequency modulation receiving apparatus having two intermediate-frequency band pass filters | |
| US6725027B1 (en) | Multipath noise reducer, audio output circuit, and FM receiver | |
| US20070033015A1 (en) | Noise Canceller | |
| KR100554037B1 (en) | Noise cancellor | |
| US7551743B1 (en) | Noise reduction apparatus and audio output apparatus | |
| JPS6331316A (en) | Fm noise elimination device | |
| EP0044687A1 (en) | Noise elimination circuit in a magnetic recording and reproducing apparatus | |
| JP2531775B2 (en) | Switching noise eliminator | |
| JP3465638B2 (en) | Noise removal device and audio output device | |
| JPH0225314B2 (en) | ||
| JP3483270B2 (en) | Multipath detector using phase comparison of stereo pilot signals | |
| JPS6266722A (en) | Receiver | |
| JPH0246570A (en) | Demodulating circuit | |
| JPS636175B2 (en) | ||
| JPH0879205A (en) | Stereo demodulator | |
| JPS6244451B2 (en) | ||
| JP2002199486A (en) | Noise eliminating device and audio unit equipment | |
| JPH0511447B2 (en) | ||
| JPH07162325A (en) | Fm receiver | |
| JPH0461068A (en) | Switching noise compensation circuit |