JPS60223347A - Noise reduction system at non-talking - Google Patents
Noise reduction system at non-talkingInfo
- Publication number
- JPS60223347A JPS60223347A JP8057984A JP8057984A JPS60223347A JP S60223347 A JPS60223347 A JP S60223347A JP 8057984 A JP8057984 A JP 8057984A JP 8057984 A JP8057984 A JP 8057984A JP S60223347 A JPS60223347 A JP S60223347A
- Authority
- JP
- Japan
- Prior art keywords
- signal
- pilot signal
- sinusoidal wave
- sine wave
- frequency
- 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
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B14/00—Transmission systems not characterised by the medium used for transmission
- H04B14/02—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation
- H04B14/04—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation using pulse code modulation
- H04B14/046—Systems or methods for reducing noise or bandwidth
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)
Abstract
Description
【発明の詳細な説明】
発明の属する技術分野
本発明は、周波数分割多重化信号（以下ＦＤＭ信号と呼
ぶ）をパルス符号変調信号（以下ＰＣＭ信号と呼ぶ）に
変換する符号化装置における無通話時雑音の低減力式に
関するものである。DETAILED DESCRIPTION OF THE INVENTION Technical field to which the invention pertains The present invention relates to a coding device that converts a frequency division multiplexed signal (hereinafter referred to as an FDM signal) into a pulse code modulated signal (hereinafter referred to as a PCM signal) during a no-call period. This relates to a noise reduction power formula.
ＦＤＭ信号をＰＣＭ信号に符号化する装［は、既設のＰ
ＤＭ信号伝送路を雑音の影響を受けにくいＰＣＭ信号伝
送路に置き換えようとする場合等に、 Ｆｌ）Ｍ信号を
ＰＣＭ信号に変換し、伝送路にＰＣＭ信号を送シ出すた
めの装置であるｏＦＤＭ信号は数十〜数百チャネルの音
声信号が周波数分割で多重化されておシ、無通話時雑音
とは各チャネルの無通話時における雑音電力のことであ
る。The equipment for encoding FDM signals into PCM signals is
When trying to replace a DM signal transmission path with a PCM signal transmission path that is less susceptible to noise, oFDM is a device that converts the Fl)M signal into a PCM signal and sends the PCM signal to the transmission path. The signal is a frequency-division multiplexing of audio signals of several tens to hundreds of channels, and noise during no-call time refers to the noise power of each channel during no-call time.
従来技術の説明
ＦＤＭ信号をＰＣＭ信号に変換する装置、逆変換する装
置及び伝送路における障害検知方式としては、送信側の
ＦＤＭ信号の帯域外に正弦波パイロット信号を挿入し、
受信側でこのパイロット信号を検出することによって、
装置及び伝送路の障害を検知する方法が用いらｎている
。Description of the Prior Art As a device for converting an FDM signal into a PCM signal, a device for inverse conversion, and a fault detection method in a transmission path, a sinusoidal pilot signal is inserted outside the band of the FDM signal on the transmitting side,
By detecting this pilot signal on the receiving side,
Methods are used to detect equipment and transmission path failures.
しかしながら、このパイロット信号にはアナログ−ディ
ジタル変換（以下Ａ／Ｄ変換と呼ぶ）の過程で量子化誤
差が発生し、これにより高調波歪を生じる。この高調波
歪は直接及び折シ返しによシ受信側のＦＤＭ信号の帯域
内に現われ、こｎが無通話時の雑音を増大させる原因と
なっていたＯ発明の目的
本発明は従来の技術に内在する上記欠点を解消する為に
なされたものであシ、従って本発明の目的は、前記パイ
ロット信号のＡ／Ｄ変換の過程で生じる高調波歪を極め
て簡易に抑え、無通話時における雑音による劣化を的確
に軽減することができる新規な方式を提供することにあ
る。However, a quantization error occurs in this pilot signal during the process of analog-to-digital conversion (hereinafter referred to as A/D conversion), resulting in harmonic distortion. This harmonic distortion appears within the band of the FDM signal on the receiving side, both directly and in return, and this causes an increase in noise during no calls. The present invention has been made in order to eliminate the above-mentioned disadvantages inherent in The object of the present invention is to provide a new method that can accurately reduce deterioration due to
発明の構成
上記目的を達成する為に、本発明に係る無通話時雑音低
減力式は、障害監視用正弦波パイロット信号を使用する
符号化装置において、更に帯域外周波数のかつ障害監視
用正弦波パイロット信号とは異なる周波数で、低レベル
の１波以上の正弦波信号を挿入することによって構成さ
れ、しかして、前述の理由による無通話時雑音の増大を
軽減しようとするものである。Composition of the Invention In order to achieve the above object, the no-call noise reduction power method according to the present invention is provided in an encoding device using a sine wave pilot signal for fault monitoring, which further uses a sine wave pilot signal of an out-of-band frequency and for fault monitoring. It is constructed by inserting one or more low-level sine wave signals at a frequency different from that of the pilot signal, and is intended to reduce the increase in no-call noise due to the above-mentioned reasons.
３、発明の詳細な説明
以下本発明をその好ましい一実施例について図面を参照
しながら詳細に説明する。3. Detailed Description of the Invention Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings.
第１図に通常のＦＤＭ信号の符号化における周波数関係
を示Ｔ０第１図において、ｆＬはＦＤＭ信号の下限周波
数、ｆＨはＦＤＭ信号の上限周波数、ＢｙはＦＤＭ信号
の帯域幅、ｆｓ ＦｉＦＤＭ信号のサンプリング周波数
をそれぞれ表わす。ここで、一般にＦＤＭ信号はＢｗ（
ｆｚであるので、送信側の入力ＦＤＭ信号が受信側の出
力に再生されるためには、サンプリング周波数ｆｓＦｉ
（１）式の条件を満たせはよい。Figure 1 shows the frequency relationship in the encoding of a normal FDM signal.T0 In Figure 1, fL is the lower limit frequency of the FDM signal, fH is the upper limit frequency of the FDM signal, By is the bandwidth of the FDM signal, and fs is the frequency of the FiFDM signal. Each represents the sampling frequency. Here, generally the FDM signal is Bw(
fz, so in order for the input FDM signal on the transmitting side to be reproduced to the output on the receiving side, the sampling frequency fsFi must be
It is good if the condition of equation (1) is satisfied.
ｆｓ≧２ＢＷ 、 ｆＨ≦ｆｓ≦２ｆｒ、、−−−−−
−−−−−−−一−−，（１）ここで、
２ｆＨ≦ｆ ｓ −−−−−−−−−−−−−−−−−
−−−−−−−−一−−−−−−（２）の条件を用いる
のが一般的ではあるが、サンプリング周波数ｆｓは小さ
い力が装置動作速度、伝送路ビットレートを低くできる
ので、ＦＤＭ信号の符号化の条件はそつう（１）が用い
られる。fs≧2BW, fH≦fs≦2fr, -----
−−−−−−−−−−, (1) where, 2fH≦f s −−−−−−−−−−−−−−−−
Although it is common to use the condition (2), the sampling frequency fs can be set with a small force because the device operating speed and transmission line bit rate can be lowered. Condition (1) is used for encoding the FDM signal.
ところで、現存のティジタル回線の階層構造（ハイアラ
ーキ）を考慮すると、サンプリング周波数ｆｓは、
ｍＸｆｓ＝１４５又は６．３又は８又は３２又はｌ ０
０ＭＨｚ ＋１１１ ＠（ただし、ｍは整数） −−−
−一−−−−−−−−（３）とすることがフレーム構成
上容易で便オＵである。By the way, considering the hierarchical structure (hierarchy) of the existing digital circuit, the sampling frequency fs is mXfs=145 or 6.3 or 8 or 32 or l 0
0MHz +111 @ (where m is an integer) ---
-1--(3) is easy and convenient in terms of frame structure.
例えば、群帯域符号化装置ではｆｚ ＝６０ＫＨｚ 、
ｆＩＩ＝１０８幻りであシ、ｍ＝１４、伝送路ピント
レートを１．５４４ｂ＆１ｚとするとサンプリング周波
数ｆｓは１１０．２９ ＫＨｚで、第１図に示すり、Ｈ
のような突き帯域ができる。For example, in a group band encoding device, fz = 60KHz,
If fII = 108, m = 14, and the transmission line pin rate is 1.544b & 1z, the sampling frequency fs is 110.29 KHz, and as shown in Figure 1, H
A band like this is created.
もし、この空き帯域がないとすると、折シ返し雑音を除
去するために急峻な竹性をもったアナログの帯域制限フ
ィルタが必要になシ、非現実的である０
従来の障害監視方式はこの空き帯域に正弦波パイロット
信号ａを挿入しているが、〜ω変換によって正弦波パイ
ロット信号には量子化誤差が生じ、Ｄ／Ａ変換後のパル
ス振幅変調さｎた信号（以下ＰＡＭ信号と呼ぶ）は、正
弦波パイロット信号ａをＡｌＣＯ５ωｔとすると、
ＡｌＣＯ３ωｔ ＋ＡｌＩ ＣＯ８２ωｔ−１−Ａｉ
ｃｏｓ ３ωｔ ＋Ａ４ ＣＯ８４ωｔ＋ａ ｍ ｍ
−−−−−（４）となシ、高調波歪成分が現わｎる。こ
の高調波歪の折シ返しが第２図のように帯域内にはいる
と、無通話時雑音が劣化することになる。第２図におい
てａ′はパイロット信号ａの折シ返しを示す。If there is no free band, an analog band-limiting filter with a steep curve will be required to remove the aliasing noise, which is unrealistic. Although a sine wave pilot signal a is inserted into the vacant band, a quantization error occurs in the sine wave pilot signal due to ~ω conversion, and a pulse amplitude modulated signal after D/A conversion (hereinafter referred to as a PAM signal) ), if the sine wave pilot signal a is AlCO5ωt, then AlCO3ωt + AlICO82ωt-1-Ai
cos 3ωt +A4 CO84ωt+a m m
-------(4), harmonic distortion components appear. If this harmonic distortion returns within the band as shown in FIG. 2, the noise during no-call time will deteriorate. In FIG. 2, a' indicates the return of the pilot signal a.
ここで、各高調波歪成分の自乗和ΣＡｋは量子に＝ｍ
化雑音電力を示し、その値は一定である。そしてその分
布は第３図に示すように、量子化ステップがあらい場合
には、
Ａｌ＋Ａ１１））Ａ４＋ＡＢ＋Ａ６＋ｓａｍｅ −−−
−−−−−−−−一−−−−−（５）となって、帯域の
端で無通話時雑音が大きくな多量子化ステップが細かい
場合には、
Ａ２さＡ３ＺＡ番さＡ６さ・・・・ −一−−−−−−
−−−−−−−−−−−−−−、（６）となシ、帯域に
分散される。Here, the sum of squares ΣAk of each harmonic distortion component represents a quantum = m noise power, and its value is constant. As shown in Fig. 3, the distribution is as shown in Fig. 3, when the quantization steps are large, Al+A11)) A4+AB+A6+same ---
------------1--------(5) When the multi-quantization step is small and the noise during no calls is large at the edge of the band, A2, A3, ZA, A6,・・・ −1−−−−−−
-------------, (6) and distributed over the band.
上述よ多量子化ステップを細かくする、即ち、正弦波パ
イロット信号の振幅ＡＸを大きくすれば無通話時雑音は
良くなるが、主信号の過負荷レベルが低下するために、
信号対量子化雑音比（以下Ｓ／Ｎ比と呼ぶ）をその分低
下させて使用することにな夛、好ましくない。従って、
パイロット信号はあるレベル以上には設定できない。As mentioned above, if the multi-quantization step is made finer, that is, if the amplitude AX of the sine wave pilot signal is increased, the noise during no calls will be improved, but since the overload level of the main signal will be reduced,
It is undesirable to reduce the signal to quantization noise ratio (hereinafter referred to as S/N ratio) by that amount. Therefore,
The pilot signal cannot be set above a certain level.
今、正弦波パイロット信号以外に第２の正弦波信号を空
き帯域に挿入することを考える０即ち、パイロット信号
をＢ ｚ ｃｏｓωｔ１第２の正弦波信号をＢｌ’ ｃ
ｏｓω′ｔとし、Ｂｘ’＼Ｂｌ、ω′＼ω、 Ｂｌ十Ｂ
ｌ’ ＝Ａｌ とする。このとき、パイロット信号と第
２の正弦波信号の和の振幅は振幅Ａ１のパイロット信号
の振幅と等しく、主信号の過負荷レベルは変らない。そ
して、パイロット信号と第２の正弦波信号の和の信号
Ｂｌ ｃｏｓ ａ＋ｔ 十Ｂｌ’ ｃｏｓ ａ＋’ ｔ
−−−−−−−−−−−−−−−−−−−−−−−（
７）のＡ／Ｄ変換による量子化誤差の波形は、第４図（
ａ）に示すように、時間軸上に圧縮、伸長が加えられる
ために、パイロット信号だけの場合に比べ、数多くノ周
波数スペクトラムが発生する。Now, let's consider inserting a second sine wave signal into an empty band in addition to the sine wave pilot signal0, that is, the pilot signal is B z cosωt1 The second sine wave signal is Bl' c
Let osω't be Bx'\Bl, ω'\ω, Bl0B
Let l' = Al. At this time, the amplitude of the sum of the pilot signal and the second sine wave signal is equal to the amplitude of the pilot signal with amplitude A1, and the overload level of the main signal does not change. Then, the signal Bl cos a+t + Bl' cos a+' t which is the sum of the pilot signal and the second sine wave signal
−−−−−−−−−−−−−−−−−−−−−−−(
The waveform of the quantization error due to A/D conversion in 7) is shown in Figure 4 (
As shown in a), since compression and expansion are applied on the time axis, more frequency spectra are generated than in the case of only the pilot signal.
前述のように、量子化誤差による量子化雑音電力は一定
であるので、数多くの周波数スペクトラムに分散さｎる
ことにより、第４図（ｂ）に示すように、量子化雑音の
スペクトラムのかたよシが少なくなる。As mentioned above, since the quantization noise power due to the quantization error is constant, by distributing it over many frequency spectra, the shape of the quantization noise spectrum changes as shown in Figure 4(b). becomes less.
以上のように、正弦波パイロット信号以外に第２の正弦
波信号を空き帯域に挿入することによシ、効果的に無通
話雑音が改善される。同様に、第３の正弦波信号、第４
の正弦波信号を空き帯域に挿入することによυ、更に大
きく無通話時雑音が改善される。As described above, by inserting the second sine wave signal in addition to the sine wave pilot signal into the vacant band, no-call noise can be effectively improved. Similarly, the third sine wave signal, the fourth
By inserting a sine wave signal of υ into the vacant band, the no-call noise can be further improved by υ.
以上、正弦波信号を空き帯域に挿入する場合を説明した
が、同空き帯域に低レベルの雑音信号を挿入しても効果
があるのは明らかである。The case where a sine wave signal is inserted into an empty band has been described above, but it is clear that inserting a low-level noise signal into the same empty band is also effective.
第５図に本発明の実施例を示す。第５図において、ＦＤ
Ｍ信号は、帯域制限フィルタｌによシ帯域外成分が除去
され、〜Φ変換器３によＪ ＰＣＭ信号に変換されて伝
送路に送り出される。FIG. 5 shows an embodiment of the present invention. In Figure 5, FD
The M signal has out-of-band components removed by a band-limiting filter l, is converted into a J PCM signal by a ~Φ converter 3, and is sent out to a transmission path.
受信側では、このＰＣＭ信号がＤ／Ａ変換器４により
ＰＡＭ信号に変換される。このＰＡＭ信号は、次いで帯
域制限フィルタ５によって不要帯域成分が除去され、Ｆ
ＤＭ信号が再生される。周波数ｆｐの障害検知用正弦波
パイロット信号はパイロット信号発生源６で生成され、
第２の正弦波信号を発生する正弦波発生源７で生成され
た周波数ｆ ｐｌの正弦波とともにＡ／Ｄ変換器３の前
に設けらｎた加算器２でＦＤＭ信号に加算される。On the receiving side, this PCM signal is processed by the D/A converter 4.
It is converted into a PAM signal. This PAM signal is then filtered by a band-limiting filter 5 to remove unnecessary band components, and F
The DM signal is played. A fault detection sine wave pilot signal of frequency fp is generated by a pilot signal generation source 6,
The second sine wave signal is added to the FDM signal by an adder 2 provided in front of the A/D converter 3 together with a sine wave having a frequency fpl generated by a sine wave generation source 7 that generates a second sine wave signal.
受信側ではＤ／Ａ変換器４の後で分岐された信号をｆｐ
の遮断周波数をもつ低域通過フィルタ８に通す。このフ
ィルタ８を通る信号は障害検知用正弦波ハイロット信号
のみでアシ、このフィルタ８の出力はパイロット信号検
出回路９でレベル又は位相が監視される。On the receiving side, the branched signal after the D/A converter 4 is sent to fp.
The signal is passed through a low-pass filter 8 having a cut-off frequency of . The signal passing through this filter 8 is only a sine wave high lot signal for failure detection, and the level or phase of the output of this filter 8 is monitored by a pilot signal detection circuit 9.
発明の効果
以上の説明で明らかなように、本発明によれば、障害監
視用の正弦波パイロット信号の高調波歪成分による無通
話時雑音の増大が軽減的確にできる効果が得らｎる。Advantages of the Invention As is clear from the above description, the present invention provides an effect in which the increase in no-call noise due to harmonic distortion components of a sine wave pilot signal for failure monitoring can be reduced and accurately.
第１図はＦＤＭ信号の符号化における周波数関係を示す
図、第２図は障害検知用パイロット信号に起因する高調
波歪が発生している様子を示Ｔ図、第３図は正弦波パイ
ロット信号による量子化雑音スペクトラムの量子化ステ
ップの大きさによる相違を示す図、第４図（ａ）、（ｂ
）、（Ｃ）は正弦波パイロット信号以外に第２の正弦波
信号を加えた場合のＰＡＭ信号、量子化雑音、量子化雑
音スペクトラムを示す図、第５図は本発明の一実施例を
示すブロック構成図である。
ｌ・・・帯域制限フィルタ、２＠・・信号加算器、３・
ｅ・アナログーテイジタル変換器、４・−・ディジタル
−アナログ変換器、５・・φ帯域制限フィルタ、６・・
・パイロット信号発生源、７・・・第２の正弦波信号発
生似、８・［相］・低域通過フィルタ、９＠・９パイロ
ット信号検出回路特許出願人 日本電気株式会社
代 理 人 弁理士 熊谷雄太部Figure 1 is a diagram showing the frequency relationship in FDM signal encoding, Figure 2 is a T diagram showing how harmonic distortion occurs due to the pilot signal for failure detection, and Figure 3 is a sine wave pilot signal. Figures 4(a) and 4(b) show the differences in the quantization noise spectrum depending on the size of the quantization step.
), (C) are diagrams showing a PAM signal, quantization noise, and quantization noise spectrum when a second sine wave signal is added in addition to the sine wave pilot signal, and FIG. 5 shows an embodiment of the present invention. FIG. 2 is a block configuration diagram. l...Band limit filter, [email protected] adder, 3.
e.Analog-to-digital converter, 4.--Digital-to-analog converter, 5..φ band limit filter, 6..
・Pilot signal generation source, 7...similar to second sine wave signal generation, 8.[phase]・Low pass filter, 9@・9 pilot signal detection circuit Patent applicant NEC Corporation Representative Patent attorney Yutabu Kumagai
Claims (1)
を障害監視用として使用する周波数分割多重化信号用符
号化装置において、更に前記正弦波パイロット信号の周
波数とは異な）■１つ帯域外であって低レベルの一波以
上の正弦波信号または雑音信号を挿入して符号化するよ
うにしたことを特徴とする無通話時雑音低減力式。In a frequency division multiplexed signal encoding device that inserts a sine wave pilot signal and uses the sine wave pilot signal for fault monitoring, the sine wave pilot signal has a frequency that is different from the frequency of the sine wave pilot signal) and is outside the band. A method for reducing noise during no-call operation, characterized in that one or more low-level sine wave signals or noise signals are inserted and encoded.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8057984A JPS60223347A (en) | 1984-04-20 | 1984-04-20 | Noise reduction system at non-talking |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8057984A JPS60223347A (en) | 1984-04-20 | 1984-04-20 | Noise reduction system at non-talking |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS60223347A true JPS60223347A (en) | 1985-11-07 |
Family
ID=13722253
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8057984A Pending JPS60223347A (en) | 1984-04-20 | 1984-04-20 | Noise reduction system at non-talking |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60223347A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0266751A2 (en) * | 1986-11-07 | 1988-05-11 | ANT Nachrichtentechnik GmbH | Digital signal-processing method and system |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS535519A (en) * | 1976-07-05 | 1978-01-19 | Kokusai Denshin Denwa Co Ltd | System for dtecting failure of multiplex signal convertors |
| JPS5612144A (en) * | 1979-07-11 | 1981-02-06 | Mitsubishi Electric Corp | Dither |
-
1984
- 1984-04-20 JP JP8057984A patent/JPS60223347A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS535519A (en) * | 1976-07-05 | 1978-01-19 | Kokusai Denshin Denwa Co Ltd | System for dtecting failure of multiplex signal convertors |
| JPS5612144A (en) * | 1979-07-11 | 1981-02-06 | Mitsubishi Electric Corp | Dither |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0266751A2 (en) * | 1986-11-07 | 1988-05-11 | ANT Nachrichtentechnik GmbH | Digital signal-processing method and system |
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