JPH06125319A - Fm stereo receiver - Google Patents

Fm stereo receiver

Info

Publication number
JPH06125319A
JPH06125319A JP29922592A JP29922592A JPH06125319A JP H06125319 A JPH06125319 A JP H06125319A JP 29922592 A JP29922592 A JP 29922592A JP 29922592 A JP29922592 A JP 29922592A JP H06125319 A JPH06125319 A JP H06125319A
Authority
JP
Japan
Prior art keywords
signal
circuit
stereo
demultiplexed
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.)
Pending
Application number
JP29922592A
Other languages
Japanese (ja)
Inventor
Haruo Sakata
晴夫 坂田
Yasuhiro Yoshioka
庸裕 吉岡
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Faurecia Clarion Electronics Co Ltd
Original Assignee
Clarion Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Clarion Co Ltd filed Critical Clarion Co Ltd
Priority to JP29922592A priority Critical patent/JPH06125319A/en
Publication of JPH06125319A publication Critical patent/JPH06125319A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE:To minimize the deterioration in sound quality even in the presence of multi-path by interpolating a noise in a sub band to a part of missing signal due to multi-path from a stereo noise reduction circuit so as to reduce the multi-path interference. CONSTITUTION:An output noise from a noise generator 27 is fed to sub channels #1-#N of a branching filter 8 via a switch 29 and an output 17-2 of the sub channel #2 is fed to an amplitude detector 10-2 and a gain control circuit 26-2. The output of the detector 10-2 is stored in a hold circuit 25-2 and when a switch 31-2 is turned off at a time t1, a level at the time t1 in the circuit 10-2 is subject to gain control by the circuit 26-2 with an output of the circuit 25-2. As a result, an interpolation noise signal is generated and fed to an adder circuit 18 via the switch 32-2. The noise is fed to the circuit 18 similarly to other sub bands and its output is fed to a matrix circuit 14. A signal period missing due to multi-path interference is reinforced by noise and a sense of unnaturality in the listening is avoided because of an integration effect by a de-emphasis circuit.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】本発明はFMステレオ受信装置に
関し、特に、ステレオノイズ低減方式の改善に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FM stereo receiver, and more particularly to improvement of a stereo noise reduction system.

【0002】[0002]

【従来の技術】図4は従来のステレオ受信装置によるF
M復調に伴うベースバンド信号のノイズの周波数分布図
であり、いわゆる三角ノイズとなっている。FM放送は
0〜15KHzのモノーラル(monaural)信号EMにパイ
ロット信号fp(19KHz)と2fp=38KHzをステ
レオ信号ESで振幅復調したEScos2ωptを多重し
ている。これをFM復調したベースバンド信号のノイズ
分布は図4に示したようになり、ベースバンド信号の高
周波側ほどノイズが大きくなる。このためEScos2ω
ptを復調するとステレオ信号ESはモノーラル信号E
Mに比べて約20dBほどS/Nが劣化する。
2. Description of the Related Art FIG. 4 shows an F by a conventional stereo receiver.
It is a frequency distribution diagram of the noise of the baseband signal accompanying M demodulation, and is what is called triangular noise. In FM broadcasting, a pilot signal fp (19 KHz) and EScos2ωpt obtained by amplitude demodulating 2fp = 38 KHz with a stereo signal ES are multiplexed on a monaural signal EM of 0 to 15 KHz. The noise distribution of the baseband signal obtained by FM demodulating this is as shown in FIG. 4, and the noise becomes larger on the higher frequency side of the baseband signal. Therefore, EScos2ω
When pt is demodulated, the stereo signal ES becomes the monaural signal E.
The S / N is deteriorated by about 20 dB as compared with M.

【0003】この対策として、“ステレオノイズ低減方
式”によるFM受信装置が実公平4−19862号で開
示されている。図5は実公平4−19862号で開示し
た受信装置のステレオノイズ低減回路の基本構成を示す
ブロック図である。なお、図5において部分図5Aはス
テレオノイズ低減回路の基本形であり、部分図5Bは図
5Aの変形例である。
As a countermeasure against this, an FM receiver based on the "stereo noise reduction method" is disclosed in Japanese Utility Model Publication No. 4-19862. FIG. 5 is a block diagram showing the basic configuration of the stereo noise reduction circuit of the receiving device disclosed in Japanese Utility Model Publication No. 4-19862. Note that in FIG. 5, the partial diagram 5A is a basic form of the stereo noise reduction circuit, and the partial diagram 5B is a modified example of FIG. 5A.

【0004】図5において、1はFM復調信号(ベース
バンド信号)、2,7はLPF(ローパスフィルタ)、
3,4はBPF(バンドパスフィルタ)、5は副搬送波
発生器、6は乗算回路、8,9は同一特性(分波器8の
サブチャンネル#1〜#Nと分波器9のサブチャンネル
#1〜#Nは同じ特性)の狭帯域フィルタからなる分波
器、10−1,…,10−Nは振幅検波器、11−1,
…,11−Nはゲート回路、13,18は加算回路、1
4はマトリックス回路である。
In FIG. 5, 1 is an FM demodulated signal (baseband signal), 2 and 7 are LPFs (low-pass filters),
Reference numerals 3 and 4 are BPFs (band pass filters), 5 is a subcarrier generator, 6 is a multiplication circuit, and 8 and 9 have the same characteristics (subchannels # 1 to #N of the demultiplexer 8 and subchannels of the demultiplexer 9). # 1 to #N are demultiplexers composed of narrow band filters having the same characteristics), 10-1, ..., 10-N are amplitude detectors, 11-1,
..., 11-N are gate circuits, 13 and 18 are addition circuits, 1
4 is a matrix circuit.

【0005】上記ステレオノイズ低減回路ではステレオ
放送(FM)の受信機でモノーラル信号EMはステレオ
信号ESよりもS/Nがよいのでモノーラル信号EM、
ステレオ信号ESとも分波器(狭帯域バンドパスフィル
タ群)を通してモノーラル信号の存在するサブバンドの
チャンネル(以下、サブチャンネルと記す)のみのステ
レオ信号のサブチャンネルを出力してS/Nを向上させ
ている。
In the above stereo noise reduction circuit, since the S / N ratio of the monaural signal EM is better than that of the stereo signal ES in the stereo broadcast (FM) receiver, the monaural signal EM,
Through the duplexer (narrow band band pass filter group), the stereo signal ES also outputs the sub channel of the stereo signal of only the sub band channel (hereinafter, referred to as sub channel) where the monaural signal exists to improve the S / N. ing.

【0006】具体的には、図5のステレオノイズ低減回
路では、モノーラル信号EMとステレオ信号ESの周波
数成分の相関性を前提にモノーラル信号EMのサブバン
ドが一定レベル以上のステレオ信号ESのサブバンドの
出力を使用してステレオ信号ESのステレオを改善して
いる。
Specifically, in the stereo noise reduction circuit of FIG. 5, the subband of the monaural signal EM is a subband of a certain level or higher on the premise of the correlation between the frequency components of the monaural signal EM and the stereo signal ES. Is used to improve the stereo of the stereo signal ES.

【0007】図5Aのステレオノイズ低減回路で、FM
復調信号(ベースバンド信号)1をLPF2,BPF
3,4に加える。LPF2は0〜15KHzのローパスフ
ィルタであり、FM復調信号からモノーラル信号EMを
分離し分波器8に加え、分波器8でサブチャンネル#1
〜#Nのサブバンドとする。また、LPF2で分離され
たモノーラル信号はEMはマトリックス回路14に加え
られる。
In the stereo noise reduction circuit of FIG.
Demodulated signal (baseband signal) 1 is applied to LPF2, BPF
Add to 3,4. The LPF 2 is a low-pass filter of 0 to 15 KHz, separates the monaural signal EM from the FM demodulated signal, adds it to the demultiplexer 8, and the demultiplexer 8 subchannel # 1.
~ Subband of #N. The EM of the monaural signal separated by the LPF 2 is added to the matrix circuit 14.

【0008】BPF3はfp=19KHzのパイロット信
号を抽出する狭帯域バンドパスフィルタであり、パイロ
ット信号を副搬送波発生器5に加えfp=38KHzの副
搬送波cos2ωptを発生させる。
The BPF 3 is a narrow band bandpass filter for extracting a pilot signal of fp = 19 KHz, and adds the pilot signal to the subcarrier generator 5 to generate a subcarrier cos2ωpt of fp = 38 KHz.

【0009】BPF4は38KHz±15KHzの帯域でE
Scos2ωptのステレオ変調波を抽出するバンドパス
フィルタであり、乗算回路6でその出力と副搬送波発生
器5からの副搬送波cos2ωptとの積を作り、0〜1
5KHzのローパスフィルタLPF7を通して周波数成分
としてステレオ信号ESを取り出す。取り出されたステ
レオ信号ESを分波器8と同じ特性の分波器9に加え、
分波器9でサブチャンネル#1’〜#N’のサブバンド
とする(分波器8のサブチャンネル#1〜#Nと分波器
9のサブチャンネル#1〜#Nは同じ特性である)。
BPF4 is E in the band of 38 KHz ± 15 KHz
This is a bandpass filter for extracting a stereo modulated wave of Scos2ωpt, and a product of its output and the subcarrier cos2ωpt from the subcarrier generator 5 is produced by the multiplication circuit 6, and 0 to 1 is obtained.
The stereo signal ES is taken out as a frequency component through the 5 KHz low-pass filter LPF7. The extracted stereo signal ES is added to the demultiplexer 9 having the same characteristics as the demultiplexer 8.
Sub-channels # 1 'to #N' are assigned to sub-bands by the demultiplexer 9 (sub-channels # 1 to #N of the de-multiplexer 8 and sub-channels # 1 to #N of the de-multiplexer 9 have the same characteristics. ).

【0010】以下の説明は、分波器8のサブチャンネル
#1〜#N及び分波器9のサブチャンネル#1〜#Nに
ついても同様であるが説明上繁雑さを避けるため、サブ
チャンネル#2及びサブチャンネル#2’を例として述
べる。また、図5の振幅検波器10−1〜10−N、ゲ
ート回路11−1〜11−N、信号12−1〜12−N
及び信号17−1〜17−Nについても同様である。
The following description is the same for the subchannels # 1 to #N of the demultiplexer 8 and the subchannels # 1 to #N of the demultiplexer 9, but in order to avoid complexity in the description, the subchannel # 2 and subchannel # 2 'will be described as an example. Further, the amplitude detectors 10-1 to 10-N, the gate circuits 11-1 to 11-N, and the signals 12-1 to 12-N shown in FIG.
The same applies to the signals 17-1 to 17-N.

【0011】分波器8のサブチャンネル#2の出力を振
幅検波器10−2で検波しその出力をゲート回路11−
2に加えてゲート分波器9のサブチャンネル#1’の出
力をゲートする。振幅検波器10−2の出力が一定値以
下の場合にゲート信号出力は0(ゼロ)とする。ゲート
回路11−2の出力信号12−2(ステレオ信号ESの
サブバンド信号)は加算回路13で他のサブバンド信号
出力12−1,12−3,…12−Nと合成し、図示し
ないディエンファシス回路を介してマトリックス回路1
4に加える。
The output of the sub-channel # 2 of the demultiplexer 8 is detected by the amplitude detector 10-2 and the output is detected by the gate circuit 11-.
In addition to 2, the output of the sub-channel # 1 'of the gate demultiplexer 9 is gated. The gate signal output is set to 0 (zero) when the output of the amplitude detector 10-2 is equal to or less than a certain value. The output signal 12-2 of the gate circuit 11-2 (subband signal of the stereo signal ES) is combined with the other subband signal outputs 12-1, 12-3, ... Matrix circuit 1 via emphasis circuit
Add to 4.

【0012】一方、前述したようにLPF2からのモノ
ーラル信号EMがマトリックス回路14に加えられマト
リックス回路で左右耳信号(信号15(ER)及び信号
16(EL))を得る。
On the other hand, as described above, the monaural signal EM from the LPF 2 is applied to the matrix circuit 14 to obtain left and right ear signals (signal 15 (ER) and signal 16 (EL)).

【0013】図5Bは図5Aの基本回路の変形例であ
り、図5Aにおいて、分波器8のサブバンドの出力17
−1,…,17−Nを合成する加算回路18を更に付加
し、加算回路18の出力及び加算回路13の出力をそれ
ぞれ図示しないディエンファシス回路を介してマトリッ
クス回路14に加え、左右耳信号(信号15(ER)及
び信号16(EL))を得る。
FIG. 5B is a modification of the basic circuit of FIG. 5A. In FIG. 5A, the subband output 17 of the demultiplexer 8 is shown.
An addition circuit 18 for synthesizing -1, ..., 17-N is further added, and the output of the addition circuit 18 and the output of the addition circuit 13 are added to the matrix circuit 14 via a de-emphasis circuit (not shown), and the left and right ear signals ( The signal 15 (ER) and the signal 16 (EL)) are obtained.

【0014】[0014]

【発明が解決しようとする課題】上述のステレオノイズ
低減回路はステレオ信号のノイズ低減を図ったものであ
り、FM移動受信の他の問題点であるマルチパス妨害に
対しては対策を講じていない。
The above-mentioned stereo noise reduction circuit is intended to reduce the noise of the stereo signal and does not take measures against multipath interference which is another problem of FM mobile reception. .

【0015】図6Aは受信電界強度(IF信号の振幅)
の分布図であり、移動受信では時間分布になる。マルチ
パス妨害は、特に、移動受信時において音質劣化の要因
となっており、例えば、図6Aで時刻t=t1,t=t
2の建物等の妨害物による反射波と直接波が合成され
て、搬送波の位相が逆相の場合には著しく受信電界が低
下する。受信電界がFM受信のスレッシュホールド以下
となると、FM復調信号は著しくS/Nが劣化した状態
になり、聴くに耐えないノイズを発生する。言い替えれ
ば、図5のステレオノイズ低減回路はステレオ信号ES
のノイズ低減には効果があるが、図6Aに示したような
マルチパス妨害には効果がないという問題点がある。
FIG. 6A shows the received electric field strength (amplitude of the IF signal).
Is a distribution chart of, and becomes a time distribution in mobile reception. Multipath interference is a factor of sound quality deterioration especially during mobile reception. For example, at time t = t1, t = t in FIG. 6A.
The reflected wave and the direct wave due to the obstacle such as the building 2 are combined, and when the phase of the carrier wave is the opposite phase, the reception electric field is significantly reduced. When the reception electric field falls below the FM reception threshold, the FM demodulated signal is in a state where the S / N is significantly deteriorated, and noise unbearable for listening is generated. In other words, the stereo noise reduction circuit of FIG.
However, there is a problem that it is not effective for multipath interference as shown in FIG. 6A.

【0016】本発明は上記問題点に鑑みてなされたもの
であり、ステレオ放送の受信で弱電界でのステレオ信号
のS/N比改善に効果のあるステレオノイズ低減回路を
有するFM受信機において、マルチパス妨害に低減の対
策を施し、マルチパス妨害があっても音質の劣化を最小
にとどめ得るステレオノイズ低減回路を用いたFM受信
機を提供することを目的とする。
The present invention has been made in view of the above problems, and in an FM receiver having a stereo noise reduction circuit effective for improving the S / N ratio of a stereo signal in a weak electric field during reception of stereo broadcasting, It is an object of the present invention to provide an FM receiver using a stereo noise reduction circuit that takes measures to reduce multipath interference and can minimize deterioration of sound quality even if there is multipath interference.

【0017】[0017]

【課題を解決するための手段】短時間の音響(音声)信
号の断(欠落)には欠落部分にノイズを挿入することに
より聴感的には支障なく聴けることが知られている。本
発明ではステレオノイズ低減回路がサブバンドに分解し
ているのでオーディオ信号で使用しているサブバンドの
みのノイズをマルチパス妨害による欠落部分に挿入して
マルチパス妨害による音質の劣化を防止することによ
り、上記の目的を達成する。
It is known that, when a sound (voice) signal is interrupted (missed) for a short period of time, noise is inserted into the missing portion so that the sound can be heard audibly. In the present invention, since the stereo noise reduction circuit is decomposed into subbands, noise of only the subbands used in the audio signal is inserted into the missing portion due to multipath interference to prevent deterioration of sound quality due to multipath interference. Thus, the above-mentioned object is achieved.

【0018】具体的には本発明のFMステレオ受信装置
は、IF信号をFM復調して得た出力信号をモノーラル
成分信号及びステレオ成分信号に分離する成分信号分離
手段と、各成分信号を複数の異なる中心周波数に設定さ
れたフィルタにより分波してモノーラル分波信号及びス
テレオ分波信号をそれぞれ出力する信号分波手段と、モ
ノーラル分波信号が所定レベル以上の時、対応するステ
レオ分波信号とモノーラル分波信号とを合成処理して左
右耳信号を得る分波信号合成処理手段と、を有するFM
ステレオ受信装置において、IF信号を振幅検波し振幅
検波信号を得ると共に、該振幅検波信号と所定の基準信
号とを比較し電界強度に応じた比較信号を得る振幅検波
手段と、雑音成分信号に基づいた所定の補間信号を各成
分信号に対応させて信号分波手段に与えるための補間信
号発生手段と、比較信号に基づいて、弱電界時には各成
分信号を補間信号に切換え、対応する信号分波手段に与
える第1の切換え手段と、比較信号に基づいて、弱電界
時には信号分波手段からの強電界時の出力レベルを検出
して対応するレベル制御信号を得るレベル制御手段と、
レベル制御信号に応じて補間信号で該信号分波手段から
の各分波信号を補間処理する信号補間処理手段と、第1
の切換え手段に対応して弱電界時には補間処理された分
波信号を分波信号合成処理手段で合成処理するように切
換える第2の切換え手段と、を有することを特徴とす
る。
Specifically, the FM stereo receiver of the present invention comprises a component signal separating means for separating an output signal obtained by FM demodulating an IF signal into a monaural component signal and a stereo component signal, and a plurality of each component signal. A signal demultiplexing unit that demultiplexes by the filters set to different center frequencies and outputs a monaural demultiplexed signal and a stereo demultiplexed signal, respectively, and a corresponding stereo demultiplexed signal when the monaural demultiplexed signal is equal to or higher than a predetermined level. And a demultiplexed signal synthesizing processing unit for synthesizing the monaural demultiplexed signal to obtain left and right ear signals.
In the stereo receiver, the IF signal is amplitude-detected to obtain an amplitude detection signal, and the amplitude detection signal is compared with a predetermined reference signal to obtain a comparison signal according to the electric field strength. Based on the comparison signal, the interpolation signal generating means for giving the predetermined demultiplexing signal to the signal demultiplexing means in correspondence with each component signal, each component signal is switched to the interpolation signal when the electric field is weak, and the corresponding signal demultiplexing is performed. First switching means provided to the means, and level control means for detecting the output level from the signal demultiplexing means in the strong electric field during the weak electric field to obtain a corresponding level control signal based on the comparison signal;
Signal interpolation processing means for interpolating each demultiplexed signal from the signal demultiplexing means with an interpolation signal according to the level control signal;
Corresponding to the switching means, the second switching means is configured to switch so that the demultiplexed signal interpolated in the weak electric field is synthesized by the demultiplexed signal synthesis processing means.

【0019】[0019]

【作用】上記構成により、本発明のFMステレオ受信装
置は、成分信号分離手段によりIF信号をFM復調して
得た出力信号をモノーラル成分信号及びステレオ成分信
号に分離し、信号分波手段により各成分信号を複数の異
なる中心周波数に設定されたフィルタにより分波してモ
ノーラル分波信号及びステレオ分波信号をそれぞれ出力
し、分波信号合成処理手段によりモノーラル分波信号が
所定レベル以上の時、対応するステレオ分波信号とモノ
ーラル分波信号とを合成処理して左右耳信号を得る。そ
して、振幅検波手段によりIF信号を振幅検波し振幅検
波信号を得ると共に、該振幅検波信号と所定の基準信号
とを比較し電界強度に応じた比較信号を得て、補間信号
発生手段により雑音成分信号に基づいた所定の補間信号
を各成分信号に対応させて信号分波手段に与え、第1の
切換え手段が、比較信号に基づいて、弱電界時には各成
分信号を補間信号に切換えて対応する信号分波手段に与
え、レベル制御手段が、比較信号に基づいて、弱電界時
には信号分波手段からの強電界時の出力レベルを検出し
て対応するレベル制御信号を得て、信号補間処理手段に
よりレベル制御信号に応じて補間信号で該信号分波手段
からの各分波信号を補間処理し、第2の切換え手段によ
り第1の切換え手段に対応して弱電界時には補間処理さ
れた分波信号を分波信号合成処理手段で合成処理するよ
うに切換える。
With the above construction, the FM stereo receiver of the present invention separates the output signal obtained by FM demodulating the IF signal by the component signal separating means into a monaural component signal and a stereo component signal, and by the signal demultiplexing means. When the component signal is demultiplexed by the filters set to a plurality of different center frequencies, the monaural demultiplexed signal and the stereo demultiplexed signal are respectively output, and when the demultiplexed signal synthesizing means has the monaural demultiplexed signal at a predetermined level or higher, The corresponding stereo demultiplexed signal and monaural demultiplexed signal are combined to obtain left and right ear signals. Then, the IF signal is amplitude-detected by the amplitude detection means to obtain an amplitude detection signal, the amplitude detection signal is compared with a predetermined reference signal to obtain a comparison signal according to the electric field strength, and the interpolation signal generation means is used to generate a noise component. A predetermined interpolation signal based on the signal is provided to the signal demultiplexing means in association with each component signal, and the first switching means responds by switching each component signal to the interpolation signal when the electric field is weak based on the comparison signal. The signal level is supplied to the signal demultiplexing means, and the level control means detects the output level from the signal demultiplexing means at the time of the strong electric field based on the comparison signal to obtain the corresponding level control signal, and the signal interpolation processing means. According to the level control signal, each demultiplexed signal from the signal demultiplexing unit is interpolated by the interpolating signal, and the demultiplexed signal is interpolated by the second switching unit corresponding to the first switching unit when the electric field is weak. Signal It switched to combine treatment with a wave signal synthesis processing unit.

【0020】[0020]

【実施例】図1は本発明のステレオノイズ低減回路の基
本構成を示すブロック図であり、記号1,2〜11−
1,…,11−Nの構成は図5BのFM復調信号1,L
PF2〜ゲート回路11−1,…,11−Nの示す構成
と同様である。また、記号13,18及び14は図5B
の加算回路13,18及びマトリックス回路14の示す
構成と同様である。
1 is a block diagram showing the basic configuration of a stereo noise reduction circuit according to the present invention.
, ..., 11-N has the FM demodulated signal 1, L of FIG. 5B.
The configuration is the same as that of the PF2 to gate circuits 11-1, ..., 11-N. Further, symbols 13, 18 and 14 are shown in FIG. 5B.
The configuration is the same as that of the adder circuits 13 and 18 and the matrix circuit 14.

【0021】なお、19はIF信号(FM波;中間周波
数)、20はFM復調器、21は振幅検波器、22は振
幅比較回路、23は基準電圧(V=er)、24は遅延
回路、25−1,…,25−Nはホールド回路、26−
1,…,26−Nは利得制御回路、27,28はノイズ
発生器、29,30,31−1,…,31−N、32−
1,…,32−Nは電子スイッチ、33,34−1,
…,34−Nは制御パルスである。
Reference numeral 19 is an IF signal (FM wave; intermediate frequency), 20 is an FM demodulator, 21 is an amplitude detector, 22 is an amplitude comparison circuit, 23 is a reference voltage (V = er), 24 is a delay circuit, 25-1, ..., 25-N are hold circuits, 26-
, ..., 26-N are gain control circuits, 27, 28 are noise generators, 29, 30, 31-1, ..., 31-N, 32-
1, ..., 32-N are electronic switches, 33, 34-1,
..., 34-N are control pulses.

【0022】また、LPF2は成分信号分離手段に、分
波器8,9は信号分波手段に、ノイズ発生器27,28
は補間信号発生手段に、電子スイッチ29,30は第1
の切換え手段に、利得制御回路26−1,…,26−N
は信号補間処理手段に、電子スイッチ32−1,…,3
2−Nは第2の切換え手段に相当し、BPF4〜LPF
7も成分信号分離手段を、加算回路13及びマトリック
ス回路14または加算回路13,18及びマトリックス
回路14は分波信号合成処理手段を、振幅検波器21及
び振幅比較回路22は振幅検波手段を、電子スイッチ3
1−1,…,31−N及びホールド回路25−1,…,
25−Nはレベル制御手段を構成する。
The LPF 2 serves as the component signal separating means, the demultiplexers 8 and 9 serve as the signal demultiplexing means, and the noise generators 27 and 28.
Is the interpolation signal generating means, and the electronic switches 29, 30 are the first
, 26-N to the gain control circuits 26-1, ..., 26-N.
Is an electronic switch 32-1, ...
2-N corresponds to the second switching means, and BPF4 to LPF
7 is also a component signal separating means, the adding circuit 13 and the matrix circuit 14 or the adding circuits 13, 18 and the matrix circuit 14 is a demultiplexing signal combining processing means, and the amplitude detector 21 and the amplitude comparing circuit 22 are amplitude detecting means. Switch 3
1-1, ..., 31-N and hold circuits 25-1, ...,
25-N constitutes level control means.

【0023】図1に示したステレオノイズ低減回路と図
5Bに示したステレオノイズ低減回路とは、図1のステ
レオノイズ低減回路では図5Bのステレオノイズ低減回
路の入力側にFM復調回路20〜遅延回路24の構成を
付加した点と、分波器8,9の出力側と加算回路13,
18の間に電子スイッチ31−1,…,31−N、ホー
ルド回路25−1,…,25−N、利得制御回路26−
1,…,26−N及び電子スイッチ32−1,…,32
−Nの構成を付加した点と、LPF2と分波器8の間に
ノイズ発生器27及び電子スイッチ29を付加し、LP
F7と分波器9の間にノイズ発生器28及び電子スイッ
チ30を付加した点と、で異なり、LPF2〜LPF7
の間の動作と、分波器8,9〜ゲート回路11−1,
…,11−Nと、加算回路13,18及び〜マトリック
ス回路14の間の動作は図5の説明で述べた通りであ
る。
The stereo noise reduction circuit shown in FIG. 1 and the stereo noise reduction circuit shown in FIG. 5B are similar to the stereo noise reduction circuit shown in FIG. The point where the configuration of the circuit 24 is added, the output side of the demultiplexers 8 and 9 and the addition circuit 13,
, 18-, electronic switches 31-1, ..., 31-N, hold circuits 25-1, ..., 25-N, gain control circuit 26-
1, ..., 26-N and electronic switches 32-1, ..., 32
A noise generator 27 and an electronic switch 29 are added between the LPF 2 and the demultiplexer 8 in addition to the point where the configuration of -N is added.
The difference is that a noise generator 28 and an electronic switch 30 are added between the F7 and the demultiplexer 9, and LPF2 to LPF7 are different.
Between, and the demultiplexers 8 and 9 to the gate circuit 11-1,
, 11-N and the addition circuits 13, 18 and the matrix circuit 14 operate as described in the description of FIG.

【0024】そこで本実施例の説明について図5Bの説
明と重複する部分については省略し、付加された構成に
関連する部分について述べるものとする。
Therefore, in the explanation of the present embodiment, the portions which overlap the explanation of FIG. 5B will be omitted, and the portions relating to the added configuration will be explained.

【0025】図1において、IF信号19はFM復調器
20及び振幅検波器21に加えられる。そして、FM復
調器20でベースバンド信号1として復調されLPF
2,BPF3,4に加えられると共に振幅検波器21で
IF振幅(従って、受信電界)を検出し、図6Aに示す
ような分布の信号を得る。
In FIG. 1, the IF signal 19 is applied to an FM demodulator 20 and an amplitude detector 21. Then, the FM demodulator 20 demodulates it as the baseband signal 1 to obtain the LPF.
2, the BPFs 3 and 4, and the amplitude detector 21 detects the IF amplitude (and therefore the received electric field) to obtain a signal having a distribution as shown in FIG. 6A.

【0026】振幅比較回路22は振幅検波器21の出力
信号を基準電圧23(V=er)と比較して振幅検波器
21の出力信号が基準電圧er以下のときに出力する。
具体的には基準電圧erをFM復調のスレッシュホール
ドに対応させる。これにより振幅比較回路22の出力は
図6Bに示すt1,t2のような波形のパルスとして出
力する。振幅比較回路22の出力をタップ付遅延回路2
4に加える。
The amplitude comparison circuit 22 compares the output signal of the amplitude detector 21 with the reference voltage 23 (V = er) and outputs it when the output signal of the amplitude detector 21 is equal to or lower than the reference voltage er.
Specifically, the reference voltage er is made to correspond to the FM demodulation threshold. As a result, the output of the amplitude comparison circuit 22 is output as a pulse having a waveform such as t1 and t2 shown in FIG. 6B. The output of the amplitude comparison circuit 22 is connected to the delay circuit 2 with taps.
Add to 4.

【0027】遅延回路24はFM復調やフィルタによる
遅延時間の調整を行う。遅延回路24の出力は図6Cに
示すような遅延時間τNを伴う制御パルスとなる。電子
スイッチ29,30,31−1,…,31−N,32−
1,…,32−Nは遅延回路24からの制御パルス33
または34−1,…,34−Nにより制御され、上記各
電子スイッチは、強電界では図1において各スイッチ部
分で実線で示している接続をなし、弱電界では図6Bや
図6Cに示すパルスの部分(t1〜τ1またはt1〜τ
N)では図1のスイッチ部分で破線で示している接続を
なす。
The delay circuit 24 adjusts the delay time by FM demodulation or a filter. The output of the delay circuit 24 becomes a control pulse with a delay time τN as shown in FIG. 6C. Electronic switches 29, 30, 31-1, ..., 31-N, 32-
, ..., 32-N are control pulses 33 from the delay circuit 24.
, 34-N, or 34-1, ..., 34-N, the electronic switches make the connections shown by the solid lines in FIG. 1 in the strong electric field, and the pulses shown in FIGS. 6B and 6C in the weak electric field. Part (t1 to τ1 or t1 to τ)
In N), the connection shown by the broken line is made in the switch portion of FIG.

【0028】電子スイッチ29は弱電界で破線の位置に
なるとノイズ発生器27の0〜15kHzのノイズを遅延
回路24からの制御パルス33により選択する。
The electronic switch 29 selects the noise of 0 to 15 kHz of the noise generator 27 by the control pulse 33 from the delay circuit 24 when the position of the broken line is reached by the weak electric field.

【0029】以下の説明は、説明上繁雑さを避けるため
分波器8の出力についてサブチャンネル#2を、分波器
9の出力についてサブチャンネル#2’を例として述べ
るが、他のサブチャンネルについても同様である。ま
た、図1の振幅検波器10−1〜10−N、ゲート回路
11−1〜11−N、信号12−1〜12−N、ホール
ド回路25−1,…,25−N、利得制御回路26−
1,…,26−N及び電子スイッチ31−1,…,31
−N,32−1,…,32−N及び信号制御パルス34
−1〜34−Nについても同様である。
In the following description, in order to avoid complexity in the description, the output of the demultiplexer 8 will be described as subchannel # 2, and the output of the demultiplexer 9 will be described as subchannel # 2 ', but other subchannels will be described. Is also the same. Further, the amplitude detectors 10-1 to 10-N, the gate circuits 11-1 to 11-N, the signals 12-1 to 12-N, the hold circuits 25-1, ..., 25-N and the gain control circuit of FIG. 26-
, ..., 26-N and electronic switches 31-1, ..., 31
-N, 32-1, ..., 32-N and signal control pulse 34
The same applies to -1 to 34-N.

【0030】ノイズ発生器27からの出力ノイズは電子
スイッチ29を経て分波器8のフィルタ群(サブチャン
ネル#1〜#N)に供給される。サブチャンネル#2の
出力信号17−2は振幅検波器10−2及び利得制御回
路26−2に加えられる。
The output noise from the noise generator 27 is supplied to the filter group (subchannels # 1 to #N) of the demultiplexer 8 via the electronic switch 29. The output signal 17-2 of subchannel # 2 is applied to the amplitude detector 10-2 and the gain control circuit 26-2.

【0031】振幅検波器10−2は図2Aに示すように
サブチャンネル#2の信号のエンべローブを出力してい
るが、t=t1〜t1’まで断となる。振幅検波器10
−2の出力はホールド回路25−2に記憶され、電子ス
イッチ31−2がt=t1でオフとなると図2Aのよう
に振幅検波回路10−2のt=t1時のレベルをホール
ドしホールド回路25−2の出力で利得制御回路26−
2の利得制御を行い、図2Bに示す補間信号(ノイズ)
を作り、電子スイッチ32−2を経て加算回路18に加
えられる。他のサブバンド同様にして加算回路18に加
えられる。加算回路18の出力は図示しないディエンフ
ァシス回路を経てマトリックス回路14に加えられる。
Although the amplitude detector 10-2 outputs the envelope of the signal of the sub-channel # 2 as shown in FIG. 2A, it is disconnected from t = t1 to t1 '. Amplitude detector 10
2 is stored in the hold circuit 25-2, and when the electronic switch 31-2 is turned off at t = t1, the level of the amplitude detection circuit 10-2 at t = t1 is held and held by the hold circuit as shown in FIG. 2A. The output of 25-2 is the gain control circuit 26-
2 gain control is performed, and the interpolation signal (noise) shown in FIG. 2B is obtained.
Is added to the adder circuit 18 via the electronic switch 32-2. It is added to the adder circuit 18 in the same manner as the other subbands. The output of the adder circuit 18 is applied to the matrix circuit 14 via a de-emphasis circuit (not shown).

【0032】電界強度がt=t1〜t1’でFM復調の
スレッシュホールド以上に復元すると各電子スイッチは
実線の位置となり、音声信号となる。図3Aはマルチパ
ス妨害で欠落した信号区間aをノイズで補強して図3B
に示す信号にした例を示している。これによりディエン
ファシス回路による積分効果も伴い、聴感上の不自然感
はない。
When the electric field strength is restored from t = t1 to t1 'to a value equal to or higher than the FM demodulation threshold, each electronic switch becomes a position indicated by a solid line, and an audio signal is obtained. FIG. 3A shows the case where the signal section a which is missing due to multipath interference is reinforced by noise.
The example shown in FIG. As a result, the de-emphasis circuit also has the effect of integration, and there is no unnatural feeling in hearing.

【0033】図1ではステレオチャンネルにノイズ発生
器28を設けてあるが、ノイズ発生器27とノイズ発生
器28は共通でもよい。また、ステレオチャンネル側の
制御動作はモノーラル信号チャンネル側とほぼ同様であ
り、分波器9のサブチャンネル#2’の出力は振幅検波
器10−2の出力によりゲート回路11−2でゲートさ
れ弱電界時のノイズ成分をホールドしないようにする。
Although the noise generator 28 is provided in the stereo channel in FIG. 1, the noise generator 27 and the noise generator 28 may be common. The control operation on the stereo channel side is almost the same as that on the monaural signal channel side, and the output of the subchannel # 2 'of the demultiplexer 9 is weakly gated by the gate circuit 11-2 by the output of the amplitude detector 10-2. Do not hold the noise component at the time of electric field.

【0034】ゲート回路11−2の出力は加算回路13
に加えられる。他のサブバンドも同様にして加算回路1
3に加えられる。加算回路13の出力は図示しないディ
エンファシス回路を経てマトリックス回路14に加えら
れる。
The output of the gate circuit 11-2 is the addition circuit 13
Added to. In the same manner for the other subbands, adder circuit 1
Added to 3. The output of the adder circuit 13 is added to the matrix circuit 14 via a de-emphasis circuit (not shown).

【0035】なお、遅延回路24の出力の制御パルス3
3,34−1,…,34−Nはサブバンドのフィルタに
よる遅延時間を考慮したものであり、遅延時間が等しい
系では同一の制御パルスを使用する。
The control pulse 3 of the output of the delay circuit 24
, 34-N consider the delay time due to the sub-band filter, and the same control pulse is used in the system in which the delay times are equal.

【0036】[0036]

【発明の効果】以上説明したように本発明のFMステレ
オ受信装置によれば、短時間の音声信号の欠落よりも、
ノイズを挿入した方が聴感上好ましい心理現象を利用し
てステレオノイズ低減回路のマルチパスによる信号欠落
の部分にサブバンドでノイズを補間しているので、本来
のオーディオ信号の周波数成分と殆ど差がなくなり聴感
上殆どマルチパス妨害を感じなくすることができ、音質
の向上が実現される。
As described above, according to the FM stereo receiver of the present invention, it is possible to eliminate the loss of the audio signal for a short time.
The noise is interpolated in the subband in the signal missing part due to the multipath of the stereo noise reduction circuit by utilizing the psychological phenomenon that is preferable for the hearing, so there is almost no difference from the frequency component of the original audio signal. It is possible to eliminate the multipath interference from the sense of hearing and improve the sound quality.

【図面の簡単な説明】[Brief description of drawings]

【図1】本発明に基づくFMステレオ受信回路のステレ
オノイズ低減回路の基本構成を示すブロック図である。
FIG. 1 is a block diagram showing a basic configuration of a stereo noise reduction circuit of an FM stereo reception circuit according to the present invention.

【図2】ノイズによる補間の説明図である。FIG. 2 is an explanatory diagram of interpolation by noise.

【図3】ノイズによる補間の説明図である。FIG. 3 is an explanatory diagram of interpolation by noise.

【図4】従来のFMステレオ受信装置によるFM復調に
伴うベースバンド信号のノイズの周波数分布である。
FIG. 4 is a frequency distribution of noise of a baseband signal accompanying FM demodulation by a conventional FM stereo receiver.

【図5】従来技術としてのステレオノイズ低減回路の基
本構成のブロック図である。
FIG. 5 is a block diagram of a basic configuration of a stereo noise reduction circuit as a conventional technique.

【図6】受信電界強度(IF信号の振幅)の分布図であ
る。
FIG. 6 is a distribution diagram of received electric field strength (amplitude of IF signal).

【符号の説明】[Explanation of symbols]

2 ローパスフィルタ(成分信号分離手段) 3,4 バンドパスフィルタ(成分信号分離手段) 5 副搬送波発生器(成分信号分離手段) 6 乗算回路(成分信号分離手段) 7 ローパスフィルタ(成分信号分離手段) 8,9 分波器(信号分波手段) 13,18 加算回路(分波信号合成処理手段) 14 マトリックス回路(分波信号合成処理手段) 21 振幅検波器(振幅検波手段) 22 振幅比較回路(振幅検波手段) 25−1,…,25−N ホールド回路(レベル制御手
段) 26−1,…,26−N 利得制御回路(信号補間処理
手段) 27,28 ノイズ発生器(補間信号発生手段) 29,30 電子スイッチ(第1の切換え手段) 31−1,…,31−N 電子スイッチ(レベル制御手
段) 32−1,…,32−N 電子スイッチ(第2の切換え
手段)
2 low-pass filter (component signal separating means) 3, 4 band-pass filter (component signal separating means) 5 subcarrier generator (component signal separating means) 6 multiplication circuit (component signal separating means) 7 low-pass filter (component signal separating means) 8, 9 Demultiplexer (Signal demultiplexing means) 13, 18 Adder circuit (Demultiplexed signal synthesis processing means) 14 Matrix circuit (Demultiplexed signal synthesis processing means) 21 Amplitude detector (Amplitude detection means) 22 Amplitude comparison circuit ( Amplitude detection means) 25-1, ..., 25-N Hold circuit (level control means) 26-1, ..., 26-N Gain control circuit (signal interpolation processing means) 27, 28 Noise generator (interpolation signal generation means) 29,30 electronic switch (first switching means) 31-1, ..., 31-N electronic switch (level control means) 32-1, ..., 32-N electronic switch (second) Switching means)

Claims (1)

【特許請求の範囲】[Claims] 【請求項1】 IF信号をFM復調して得た出力信号を
モノーラル成分信号及びステレオ成分信号に分離する成
分信号分離手段と、前記各成分信号を複数の異なる中心
周波数に設定されたフィルタにより分波してモノーラル
分波信号及びステレオ分波信号をそれぞれ出力する信号
分波手段と、前記モノーラル分波信号が所定レベル以上
の時、対応スる前記ステレオ分波信号とモノーラル分波
信号とを合成処理して左右耳信号を得る分波信号合成処
理手段と、を有するFMステレオ受信装置において、前
記IF信号を振幅検波し振幅検波信号を得ると共に、該
振幅検波信号と所定の基準信号とを比較し電界強度に応
じた比較信号を得る振幅検波手段と、雑音成分信号に基
づいた所定の補間信号を前記各成分信号に対応させて前
記信号分波手段に与えるための補間信号発生手段と、前
記比較信号に基づいて、弱電界時には前記各成分信号を
前記補間信号に切換え、対応する前記信号分波手段に与
える第1の切換え手段と、前記比較信号に基づいて、弱
電界時には前記信号分波手段からの強電界時の出力レベ
ルを検出して対応するレベル制御信号を得るレベル制御
手段と、前記レベル制御信号に応じて前記補間信号で該
信号分波手段からの各分波信号を補間処理する信号補間
処理手段と、前記第1の切換え手段に対応して弱電界時
には前記補間処理された分波信号を前記分波信号合成処
理手段で合成処理するように切換える第2の切換え手段
と、を有することを特徴とするFMステレオ受信装置。
1. A component signal separation means for separating an output signal obtained by FM demodulating an IF signal into a monaural component signal and a stereo component signal, and each component signal by a filter set to a plurality of different center frequencies. A signal demultiplexing unit that outputs a monaural demultiplexed signal and a stereo demultiplexed signal, respectively, and, when the monaural demultiplexed signal is at a predetermined level or higher, synthesizes the corresponding stereo demultiplexed signal and the monaural demultiplexed signal. In an FM stereo receiver having a demultiplexing signal synthesizing processing means for processing and obtaining left and right ear signals, the IF signal is amplitude-detected to obtain an amplitude detection signal, and the amplitude detection signal is compared with a predetermined reference signal. Then, an amplitude detection means for obtaining a comparison signal according to the electric field strength and a predetermined interpolation signal based on a noise component signal are given to the signal demultiplexing means in association with each of the component signals. And an interpolating signal generating means for switching the respective component signals to the interpolating signal when the electric field is weak based on the comparison signal, and a first switching means for giving to the corresponding signal demultiplexing means and the comparison signal. On the basis of the above, based on the weak electric field, the level control means for detecting the output level from the signal demultiplexing means during the strong electric field to obtain a corresponding level control signal, and the signal demultiplexing with the interpolation signal according to the level control signal Signal interpolation processing means for interpolating each demultiplexed signal from the means, and when the weak electric field corresponds to the first switching means, the interpolated demultiplexed signals are combined by the demultiplexed signal combining processing means. A second switching means for switching as described above.
JP29922592A 1992-10-12 1992-10-12 Fm stereo receiver Pending JPH06125319A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP29922592A JPH06125319A (en) 1992-10-12 1992-10-12 Fm stereo receiver

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP29922592A JPH06125319A (en) 1992-10-12 1992-10-12 Fm stereo receiver

Publications (1)

Publication Number Publication Date
JPH06125319A true JPH06125319A (en) 1994-05-06

Family

ID=17869770

Family Applications (1)

Application Number Title Priority Date Filing Date
JP29922592A Pending JPH06125319A (en) 1992-10-12 1992-10-12 Fm stereo receiver

Country Status (1)

Country Link
JP (1) JPH06125319A (en)

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