JP4136676B2 - Optical transmission equipment - Google Patents

Description

〔Ｓ６〕ＰＤ１７ａのモニタ値ＰＤ１ＭＯＮと、ＰＤ１７ｂのモニタ値ＰＤ２ＭＯＮとを取得する。
〔Ｓ７〕ＰＤ１ＭＯＮとＰthru highを比較する。ＰＤ１ＭＯＮ＞Ｐthru highならばステップＳ８へ、ＰＤ１ＭＯＮ≦Ｐthru highならばステップＳ１３へいく。すなわち、Ｔｈｒｕ光のパワーが上限値を超えている場合はステップＳ８へ、超えていない場合はステップＳ１３へいく。
〔Ｓ８〕現在の減衰設定値（Xvatt1）とＶＡＴＴ１４の最大減衰度（Xvatt1max）を比較する。Xvatt1＞Xvatt1maxならばステップＳ９へ、Xvatt1≦Xvatt1maxならばステップＳ１０へいく。すなわち、制御可能な減衰度を超えてしまう場合にはステップＳ９へ、制御範囲内ならばステップＳ１０へいく。
〔Ｓ９〕ＶＡＴＴ１４の上限アラームを発出する。
〔Ｓ１０〕ＶＡＴＴ１４の上限アラームを消失する（アラーム回復を通知）。
〔Ｓ１１〕Xvatt1＝Xvatt1＋Δにして減衰度を上げる。Δは単位ステップ当たりの減衰制御幅（きざみ幅）である。
〔Ｓ１２〕ＰＤ１ＭＯＮを取得し、ステップＳ７へ戻る。
〔Ｓ１３〕ＰＤ１ＭＯＮとＰthru lowを比較する。Ｐthru low＞ＰＤ１ＭＯＮならばステップＳ１４へ、Ｐthru low≦ＰＤ１ＭＯＮならばステップＳ１９へいく。すなわち、Ｔｈｒｕ光のパワーが下限値を下回る場合はステップＳ１４へ、下回らない場合はステップＳ１９へいく。
〔Ｓ１４〕減衰設定値（Xvatt1）とＶＡＴＴ１４の最小減衰度（Xvatt1min）を比較する。Xvatt1min＞Xvatt1ならばステップＳ１５へ、Xvatt1min≦Xvatt1ならばステップＳ１６へいく。すなわち、制御可能な減衰度より下回る場合にはステップＳ１５へ、制御範囲内ならばステップＳ１６へいく。
〔Ｓ１５〕ＶＡＴＴ１４の下限アラームを発出する。
〔Ｓ１６〕ＶＡＴＴ１４の下限アラームを消失する（アラーム回復の通知）。
〔Ｓ１７〕Xvatt1＝Xvatt1―Δにして減衰度を緩める。
〔Ｓ１８〕ＰＤ１ＭＯＮを取得し、ステップＳ１３へ戻る。
〔Ｓ１９〕ＰＤ２ＭＯＮとＰadd highを比較する。ＰＤ２ＭＯＮ＞Ｐadd highならばステップＳ２０へ、ＰＤ２ＭＯＮ≦Ｐadd highならばステップＳ２５へいく。すなわち、Ａｄｄ光のパワーが上限値を超えている場合はステップＳ２０へ、超えていない場合はステップＳ２５へいく。
〔Ｓ２０〕減衰設定値（Xvatt2）とＶＡＴＴ１５の最大減衰度（Xvatt2max）を比較する。Xvatt2＞Xvatt2maxならばステップＳ２１へ、Xvatt2≦Xvatt2maxならばステップＳ２２へいく。すなわち、制御可能な減衰度を超えてしまう場合にはステップＳ２１へ、制御範囲内ならばステップＳ２２へいく。
〔Ｓ２１〕ＶＡＴＴ１５の上限アラームを発出する。
〔Ｓ２２〕ＶＡＴＴ１５の上限アラームを消失する（アラーム回復の通知）。
〔Ｓ２３〕Xvatt2＝Xvatt2＋Δにして減衰度を上げる。
〔Ｓ２４〕ＰＤ２ＭＯＮを取得し、ステップＳ１９へ戻る。
〔Ｓ２５〕ＰＤ２ＭＯＮとＰadd lowを比較する。Ｐadd low≦ＰＤ２ＭＯＮならばステップＳ１へ戻り、Ｐadd low＞ＰＤ２ＭＯＮならばステップＳ２６へいく。すなわち、Ａｄｄ光のパワーが下限値を下回らない場合はステップＳ１へ、下回る場合はステップＳ２６へいく。
〔Ｓ２６〕減衰設定値（Xvatt2）とＶＡＴＴ１５の最小減衰度（Xvatt2min）を比較する。Xvatt2min＞Xvatt2ならばステップＳ２７へ、Xvatt2min≦Xvatt2ならばステップＳ２８へいく。すなわち、制御可能な減衰度より下回る場合にはステップＳ２７へ、制御範囲内ならばステップＳ２８へいく。
〔Ｓ２７〕ＶＡＴＴ１５の下限アラームを発出する。
〔Ｓ２８〕ＶＡＴＴ１５の下限アラームを消失する（アラーム回復の通知）。
〔Ｓ２９〕Xvatt2＝Xvatt2―Δにして減衰度を緩める。
〔Ｓ３０〕ＰＤ２ＭＯＮを取得し、ステップＳ２５へ戻る。
【００４３】
次に第２の実施の形態の光伝送装置の構成及び動作について詳しく説明する。図８は光伝送装置１０の第２の実施の形態の構成を示す図である。図２で上述した光伝送装置１０−１では、ＰＤ１７ａ、１７ｂそれぞれをＶＡＴＴ１４、１５の出力段において光パワーをモニタする構成としたが、第２の実施の形態の光伝送装置１０−２では、ＰＤ１７ｃを光合波部１６の出力段に設けて、合波された光信号のパワーをモニタする。第１の実施の形態の構成と異なる点はこの部分だけであるので、その他の構成説明は省略する。
【００４４】
次に第２の実施の形態の光伝送装置１０−２における光レベル調整制御について説明する。ここでの光レベル調整制御としては、ＶＡＴＴ１４またはＶＡＴＴ１５のいずれか一方の減衰制御幅を固定値とし、他方の減衰制御幅をＴｈｒｕ光とＡｄｄ光それぞれの波長数比から決定する。
【００４５】
そして、ＰＤ１７ｃのモニタ値が、ポストアンプ１２で規定された光レベルの上限値と下限値の範囲内に収まるように、双方の減衰制御幅（固定値の減衰制御幅と波長数比から算出した減衰制御幅）を動かして、光レベルの調整制御を行う。
【００４６】
具体例で説明する。最初に初期条件として、ポストアンプ１２に入力される光レベルの上限値を１００、ポストアンプ１２に入力される光レベルの下限値を８０とし、Ｔｈｒｕ光の波長数を１５、Ａｄｄ光の波長数を５とする。
【００４７】
ＶＡＴＴ１４の減衰度を強弱する際の減衰制御幅をΔａ、ＶＡＴＴ１５の減衰度を強弱する際の減衰制御幅をΔｂとし、Δａを固定値（＝１）、Δｂを波長数比（５／１５＝１／３）として、Δａ：Δｂ＝１：１／３の比率で減衰度を制御する。例えば、ＶＡＴＴ１４の１回の調整操作で２制御幅を動かすならば、ＶＡＴＴ１５の１回の調整操作では２／３（＝２×（１／３））制御幅を動かすことになる。
【００４８】
そして、ＮＥＭ１８ａでは、ＰＤ１７ｃからの光レベルモニタ値Ｍ３を取得し、モニタ値Ｍ３が８０≦Ｍ３≦１００になるように、制御信号を送出してＶＡＴＴ１４に対してΔａ、ＶＡＴＴ１５に対してΔｂだけ調整する。このような光レベル調整制御を行うことで、光合波部１６で合波される光信号を、ポストアンプ１２で規定される入力範囲内であり、かつ各波長の光レベルを一定となるようにすることができる。
【００４９】
次に光伝送装置１０−２における光レベル調整制御について詳細なフローチャートを用いて説明する。図９〜図１１は第２の実施の形態の光レベル調整制御のフローチャートを示す図である。なお、各ステップの動作はすべてＮＥＭ１８ａ（光レベル調整制御部１８）の動作である。
〔Ｓ４１〕光合波部１６に入るＴｈｒｕ光の波長数、または光合波部１６に入るＡｄｄ光の波長数に変更があったか否かを判断する。変更があればステップＳ４２へ、なければステップＳ４６へいく。
〔Ｓ４２〕ポストアンプ１２で規定されている入力レベル上限値（Ｐamp high）と入力レベル下限値（Ｐamp low）を取得する。
〔Ｓ４３〕ポストアンプ１２で規定されている入力レベル上限値のマージン（Ｐamp high offset）と入力レベル下限値のマージン（Ｐamp low offset）を取得する。
〔Ｓ４４〕光合波部１６による合波後、光レベル上限値Ｐall highと光レベル下限値Ｐall lowそれぞれを上述の式（１ａ）、（１ｂ）から算出する。
〔Ｓ４５〕Ｔｈｒｕ光とＡｄｄ光の波長数比により、ＶＡＴＴ１４の減衰制御幅Δａ、ＶＡＴＴ１５の減衰制御幅Δｂを求める（例えば、Δａは固定値、Δｂは波長数比から求めた値）。
〔Ｓ４６〕ＰＤ１７ｃのモニタ値ＰＤ３ＭＯＮを取得する。
〔Ｓ４７〕ＰＤ３ＭＯＮとＰall highを比較する。ＰＤ３ＭＯＮ＞Ｐall highならばステップＳ４８へ、ＰＤ３ＭＯＮ≦Ｐall highならばステップＳ５７へいく。すなわち、合波後の光のパワーが上限値を超えている場合はステップＳ４８へ、超えていない場合はステップＳ５７へいく。
〔Ｓ４８〕ＶＡＴＴ１４の減衰設定値（Xvatt1）とＶＡＴＴ１４の最大減衰度（Xvatt1max）を比較する。Xvatt1＞Xvatt1maxならばステップＳ４９へ、Xvatt1≦Xvatt1maxならばステップＳ５０へいく。すなわち、制御可能な減衰度を超えてしまう場合にはステップＳ４９へ、制御範囲内ならばステップＳ５０へいく。
〔Ｓ４９〕ＶＡＴＴ１４の上限アラームを発出する。
〔Ｓ５０〕ＶＡＴＴ１４の上限アラームを消失する（アラーム回復の通知）。
〔Ｓ５１〕Xvatt1＝Xvatt1＋Δａにして減衰度を上げる。
〔Ｓ５２〕ＶＡＴＴ１５の減衰設定値（Xvatt2）とＶＡＴＴ１５の最大減衰度（Xvatt2max）を比較する。Xvatt2＞Xvatt2maxならばステップＳ５３へ、Xvatt2≦Xvatt2maxならばステップＳ５４へいく。すなわち、制御可能な減衰度を超えてしまう場合にはステップＳ５３へ、制御範囲内ならばステップＳ５４へいく。
〔Ｓ５３〕ＶＡＴＴ１５の上限アラームを発出する。
〔Ｓ５４〕ＶＡＴＴ１５の上限アラームを消失する（アラーム回復の通知）。
〔Ｓ５５〕Xvatt2＝Xvatt2＋Δｂにして減衰度を上げる。
〔Ｓ５６〕ＰＤ３ＭＯＮを取得し、ステップＳ４７へ戻る。
〔Ｓ５７〕ＰＤ３ＭＯＮとＰall lowを比較する。Ｐall low＞ＰＤ３ＭＯＮならばステップＳ５８へ、Ｐall low≦ＰＤ３ＭＯＮならばステップＳ４１へ戻る。すなわち、合波後の光のパワーが下限値を下回る場合はステップＳ５８へ、下回っていない場合はステップＳ４１へいく。
〔Ｓ５８〕ＶＡＴＴ１４の減衰設定値（Xvatt1）とＶＡＴＴ１４の最小減衰度（Xvatt1min）を比較する。Xvatt1min＞Xvatt1ならばステップＳ５９へ、Xvatt1min≦Xvatt1ならばステップＳ６０へいく。すなわち、制御可能な減衰度より下回る場合にはステップＳ５９へ、制御範囲内ならばステップＳ６０へいく。
〔Ｓ５９〕ＶＡＴＴ１４の下限アラームを発出する。
〔Ｓ６０〕ＶＡＴＴ１４の下限アラームを消失する（アラーム回復の通知）。
〔Ｓ６１〕Xvatt1＝Xvatt1―Δａにして減衰度を緩める。
〔Ｓ６２〕ＶＡＴＴ１５の減衰設定値（Xvatt2）とＶＡＴＴ１５の最小減衰度（Xvatt2min）を比較する。Xvatt2min＞Xvatt2ならばステップＳ６３へ、Xvatt2min≦Xvatt2ならばステップＳ６４へいく。すなわち、制御可能な減衰度より下回る場合にはステップＳ６３へ、制御範囲内ならばステップＳ６４へいく。
〔Ｓ６３〕ＶＡＴＴ１５の下限アラームを発出する。
〔Ｓ６４〕ＶＡＴＴ１５の下限アラームを消失する（アラーム回復の通知）。
〔Ｓ６５〕Xvatt2＝Xvatt2―Δｂにして減衰度を緩める。
〔Ｓ６６〕ＰＤ３ＭＯＮを取得し、ステップＳ５７へ戻る。
【００５０】
次に図１で上述した光伝送装置１０とは原理構成が異なる他の光伝送装置について説明する。図１２は光伝送装置の原理図である。図１で上述した光伝送装置１０では、光カプラ１３ａからＴｈｒｕ光が出力される出力段にＶＡＴＴ１４を設け、ＶＡＴＴ１５をＭＵＸ１９の出力段に設けて、ＶＡＴＴ１４、１５から出力された後の光信号のパワーをモニタして、光レベル調整制御を行った。
【００５１】
一方、図１２に示す光伝送装置１０ａでは、ＶＡＴＴ１４は図１と同じ位置に設置してあるが、ＶＡＴＴ１５に対しては、ＭＵＸ１９の入力段に波長数分のＶＡＴＴ１５−１〜１５−ｎを設ける。そして、ＶＡＴＴ１４、ＶＡＴＴ１５−１〜１５−ｎから出力された後の光信号のパワーをモニタして光レベル調整制御を行うものである。光伝送装置１０と異なる原理ブロックはこの部分だけであるので、それ以外の原理ブロックの説明は省略する。
【００５２】
次に光伝送装置１０ａの構成及び動作について詳しく説明する。図１３は光伝送装置１０ａの第１の実施の形態の構成を示す図である。システムを構成する各中継局は、光伝送装置と、トランスポンダとで構成される。例えば、Ｂ局は光伝送装置１０ａ−１、トランスポンダＴＰで構成される（Ａ局とＣ局のトランスポンダの図示は省略）。
【００５３】
Ｂ局に対し、光伝送装置１０ａ−１は、プリアンプ１１、ポストアンプ１２、光カプラ１３ａ、ＤＭＵＸ１３ｂ、ＶＡＴＴ１４、ＶＡＴＴ１５−１〜１５−ｎ、光合波部１６、ＰＤ１７ｄ、ＰＤ１７ｅ−１〜１７ｅ−ｎ、ＮＥＭ１８ｂ、ＭＵＸ１９から構成される。ＰＤ１７ｄ、１７ｅ−１〜１７ｅ−ｎは、光モニタ部１７に該当し、光／電気変換を行う受光素子である。また、ＮＥＭ１８ｂは、光レベル調整制御部１８の機能を含み、また、光伝送装置１０ａ−１の全体制御を行う。
【００５４】
なお、Ａ局の光伝送装置２０ａ−１内の構成要素については、ポストアンプ２２のみ記載し、Ｃ局の光伝送装置３０ａ−１内の構成要素についてはプリアンプ３１のみ図示する。
【００５５】
隣り合ったＡ局、Ｂ局、Ｃ局において、Ａ局の光伝送装置２０ａ−１内のポストアンプ２２からＢ局へ出力された光信号は、光伝送路（光ファイバ）Ｆ１により伝送され、Ｂ局の光伝送装置１０ａ−１内のプリアンプ１１に入力される。
【００５６】
プリアンプ１１は、光信号を増幅し、光カプラ１３ａは、増幅された光信号をＴｈｒｕ光とＤｒｏｐ光とに分岐する。ＤＭＵＸ１３ｂは、Ｄｒｏｐ光を波長分離し、光伝送路Ｆ２によりトランスポンダＴＰへ送出する。光伝送路Ｆ２により伝送された光信号は、帯域変換を行うトランスポンダＴＰで波長変換された後、光伝送路Ｆ３により、低速なネットワークへ伝送される。
【００５７】
また、光伝送路Ｆ４により低速ネットワークから伝送されてきた光信号は、トランスポンダＴＰで波長変換された後、光伝送路Ｆ５により光伝送装置１０ａ−１へ入力される。
【００５８】
一方、ＶＡＴＴ１４は、制御信号にもとづいて、Ｔｈｒｕ光の光レベル調整を行う。ＶＡＴＴ１５−１〜１５−ｎは、制御信号にもとづいて、それぞれのＡｄｄ光を個別に光レベル調整を行う。ＭＵＸ１９は、ＶＡＴＴ１５−１〜１５−ｎから出力されたＡｄｄ光を波長多重する。光合波部１６は、光レベル調整後のＴｈｒｕ光とＡｄｄ光を合波する。ポストアンプ１２は、合波された光信号を増幅する。そして、増幅された光信号は、光伝送路Ｆ６によりＣ局の光伝送装置３０ａ−１のプリアンプ３１へ伝送される。
【００５９】
一方、ＰＤ１７ｄは、ＶＡＴＴ１４の出力信号の光レベルをモニタし、モニタ結果をＮＥＭ１８ｂへ送信する。ＰＤ１７ｅ−１〜１７−ｎは、ＶＡＴＴ１５−１〜１５−ｎの出力信号それぞれの光レベルをモニタし、モニタ結果をＮＥＭ１８ｂへ送信する。ＮＥＭ１８ｂは、モニタ結果にもとづき、ＶＡＴＴ１４、１５−１〜１５−ｎの光レベル調整制御を行う。
【００６０】
次に第１の実施の形態の光伝送装置１０ａ−１における光レベル調整制御について説明する。ここでの光レベル調整制御は、上述した光伝送装置１０−１の制御と同様である。すなわち、ポストアンプ１２の光レベルの上限値と下限値をもとに、Ｔｈｒｕ光とＡｄｄ光それぞれの波長数比から、Ｔｈｒｕ光の光レベル上限値及び下限値と、Ａｄｄ光の光レベル上限値及び下限値とを算出する。
【００６１】
そして、ＰＤ１７ｄによるモニタ値が、算出したＴｈｒｕ光の上限値と下限値の範囲内に収まるように、かつＰＤ１７ｅ−１〜１７ｅ−ｎによるそれぞれのモニタ値が、算出したＡｄｄ光の上限値と下限値の範囲内に収まるように、光レベルの調整制御を行う。
【００６２】
具体例で説明する。最初に、初期条件として、ポストアンプ１２に入力される光レベルの上限値を１００、ポストアンプ１２に入力される光レベルの下限値を８０とし、Ｔｈｒｕ光の波長数を１５、Ａｄｄ光の波長数を５とする。
【００６３】
まず、ポストアンプ１２の入力上限値が１００、Ｔｈｒｕ光の波長数が１５、Ａｄｄ光の波長数が５であるため、Ｔｈｒｕ光の上限値＝１００＊（１５／（１５＋５））＝７５となり、この値は図１３のＰ４における上限値となる。また、Ａｄｄ光の上限値＝１００＊（１／（１５＋５））＝５となり、この値は図１３のＰ５−１〜Ｐ５−ｎにおける上限値となる。なお、１／（１５＋５）の分子の１とは、ＶＡＴＴ１７ｅ−１〜１７ｅ−ｎそれぞれに入力する１波のことである。
【００６４】
同様に下限値については、Ｔｈｒｕ光の下限値＝８０＊（１５／（１５＋５））＝６０となり、この値はＰ４における下限値となる。また、Ａｄｄ光の下限値＝８０＊（１／（１５＋５））＝４となり、この値はＰ５−１〜Ｐ５−ｎにおける下限値となる。
【００６５】
そして、ＮＥＭ１８ｂでは、ＰＤ１７ｄからの光レベルモニタ値Ｍ４を取得し、このモニタ値が６０≦Ｍ４≦７５になるようにＶＡＴＴ１４に対して制御信号を送出して調節する。同様に、ＰＤ１７ｅ−１〜１７ｅ−ｎの光レベルモニタ値Ｍ５−１、Ｍ５−ｎを取得し、このモニタ値が４≦Ｍ５−１、…Ｍ５−ｎ≦５になるようにＶＡＴＴ１５−１〜１５−ｎに対して制御信号を送出して調節する。
【００６６】
このような光レベル調整制御を行うことで、光合波部１６で合波される光信号を、ポストアンプ１２で規定される入力範囲内であり、かつ各波長の光レベルを一定となるようにすることができる。
【００６７】
なお、装置規模に関しては、光伝送装置１０ａ−１では、図２の光伝送装置１０−１と比べて、ＶＡＴＴ数及びＰＤ数は多くなるが、図２１で上述したような従来の装置よりも装置規模は縮小できる。
【００６８】
次に光伝送装置１０ａ−１における光レベル調整制御について詳細なフローチャートを用いて説明する。図１４〜図１６は第１の実施の形態の光レベル調整制御のフローチャートを示す図である。なお、各ステップの動作はすべてＮＥＭ１８ｂ（光レベル調整制御部１８）の動作である。ステップＳ７７〜ステップＳ８８はＶＡＴＴ１５−１〜ＶＡＴＴ１５−ｎ（総称する場合はＶＡＴＴ１５（ｎ）と記す）の光レベル調整制御であり（ｎ回繰り返す）、ステップＳ８９〜ステップＳ１００はＶＡＴＴ１４の光レベル調整制御である。また、以降のステップＳ７１〜ステップＳ１００までのすべての動作は、基本的には上述したステップＳ１〜ステップＳ３０と同じ動作である。
〔Ｓ７１〕ＰＤ１７ｄからＴｈｒｕ光のモニタ値を取得する。
〔Ｓ７２〕ＰＤ１７ｅ−１〜１７ｅ−ｎからＡｄｄ光のモニタ値を取得する。
〔Ｓ７３〕ポストアンプ１２で規定されている入力レベル上限値（Ｐmax）と入力レベル下限値（Ｐmin）を取得する。
〔Ｓ７４〕ポストアンプ１２で規定されている入力レベル上限値のマージンと入力レベル下限値のマージンを取得する。ここでは、双方のマージンを共にαとする。
〔Ｓ７５〕実質的なポストアンプ１２の光レベル上限値（＝Ｐmax−α）と光レベル下限値（＝Ｐmin＋α）を算出する。
〔Ｓ７６〕Ｔｈｒｕ光とＡｄｄ光の波長数比により、Ｔｈｒｕ光の上限値（Ｐmax thru）と下限値（Ｐmin thru）を以下の式（３ａ）、（３ｂ）で算出し、Ａｄｄ光の上限値（Ｐmax add）と下限値（Ｐmin add）を以下の式（３ｃ）、（３ｄ）で算出する。
【００６９】
【数３】

〔Ｓ７７〕ステップＳ７２で取得したＰＤ１７ｅ−１〜１７ｅ−ｎ（総称してＰＤ１７ｅ（ｎ）と記す）によるモニタ値は、ステップＳ７６で求めた下限値から上限値までの範囲以内か否かを判断する。下限値から上限値までの範囲より低い場合はステップＳ７７へ、高い場合はステップＳ８４へ、範囲以内ならステップＳ８９へいく。
〔Ｓ７８〕ＶＡＴＴ１５（ｎ）の減衰度がゼロか否かを判断する（ゼロならステップＳ７９へ、そうでなければステップＳ８０へいく。すなわち、まったく減衰させていない場合はステップＳ７９へ、減衰度が設定されている場合は、ステップＳ８０へいく。
〔Ｓ７９〕ＶＡＴＴ１５（ｎ）の下限アラームを発生する（これ以上、光レベルを上げられないので）。
〔Ｓ８０〕下限アラームが発生中か否かを判断する。発生中ならステップＳ８１へ、そうでなければステップＳ８２へいく。
〔Ｓ８１〕ＶＡＴＴ１５（ｎ）の下限アラームを回復する。
〔Ｓ８２〕ＶＡＴＴ１５（ｎ）の減衰を弱める（光レベルを上げる）。
〔Ｓ８３〕ＰＤ１７ｅ（ｎ）からモニタ値を取得する。そして、ステップＳ７７へ戻る。
〔Ｓ８４〕ＶＡＴＴ１５（ｎ）の減衰度が最大か否かを判断する。最大ならステップＳ８５へ、そうでなければステップＳ８６へいく。
〔Ｓ８５〕ＶＡＴＴ１５（ｎ）の上限アラームを発生する（これ以上、光レベルを下げられないので）。
〔Ｓ８６〕上限アラームが発生中か否かを判断する。発生中ならステップＳ８７へ、そうでなければステップＳ８８へいく。
〔Ｓ８７〕ＶＡＴＴ１５（ｎ）の上限アラームを回復する。
〔Ｓ８８〕ＶＡＴＴ１５（ｎ）の減衰を強める（光レベルを下げる）。そして、ステップＳ８３へいく。
〔Ｓ８９〕ステップＳ７１で取得したＰＤ１７ｄによるモニタ値は、ステップＳ７６で求めた下限値から上限値までの範囲以内か否かを判断する。下限値から上限値までの範囲より低い場合はステップＳ９０へ、高い場合はステップＳ９６へ、範囲以内ならステップＳ７１へ戻る。
〔Ｓ９０〕ＶＡＴＴ１４の減衰度がゼロか否かを判断する（ゼロならステップＳ９１へ、そうでなければステップＳ９２へいく。すなわち、まったく減衰させていない場合はステップＳ９１へ、減衰度が設定されている場合は、ステップＳ９２へいく。
〔Ｓ９１〕ＶＡＴＴ１４の下限アラームを発生する（これ以上、光レベルを上げられないので）。
〔Ｓ９２〕下限アラームが発生中か否かを判断する。発生中ならステップＳ９３へ、そうでなければステップＳ９４へいく。
〔Ｓ９３〕ＶＡＴＴ１４の下限アラームを回復する。
〔Ｓ９４〕ＶＡＴＴ１４の減衰を弱める（光レベルを上げる）。
〔Ｓ９５〕ＰＤ１７ｄからモニタ値を取得する。そして、ステップＳ８９へ戻る。
〔Ｓ９６〕ＶＡＴＴ１４の減衰度が最大か否かを判断する。最大ならステップＳ９７へ、そうでなければステップＳ９８へいく。
〔Ｓ９７〕ＶＡＴＴ１４の上限アラームを発生する（これ以上、光レベルを下げられないので）。
〔Ｓ９８〕上限アラームが発生中か否かを判断する。発生中ならステップＳ９９へ、そうでなければステップＳ１００へいく。
〔Ｓ９９〕ＶＡＴＴ１４の上限アラームを回復する。
〔Ｓ１００〕ＶＡＴＴ１４の減衰を強める（光レベルを下げる）。そして、ステップＳ９５へいく。
【００７０】
次に第２の実施の形態の光伝送装置の構成及び動作について詳しく説明する。図１７は光伝送装置１０ａの第２の実施の形態の構成を示す図である。図２で上述した光伝送装置１０ａ−１では、ＰＤ１７ｄをＶＡＴＴ１４の出力段に、ＰＤｅ−１〜１７ｅ−ｎそれぞれをＶＡＴＴ１５−１〜１５−ｎの出力段において光パワーをモニタする構成としたが、第２の実施の形態の光伝送装置１０ａ−２では、ＰＤ１７ｆを光合波部１６の出力段に設けて、合波された光信号のパワーをモニタする。第１の実施の形態の構成と異なる点はこの部分だけであるので、その他の構成説明は省略する。
【００７１】
次に第２の実施の形態の光伝送装置１０ａ−２における光レベル調整制御について説明する。ここでの光レベル調整制御としては、ポストアンプ１２で規定された光レベルの上限値と下限値をもとに、Ｔｈｒｕ光とＡｄｄ光それぞれの波長数比から、Ｔｈｒｕ光の光レベル上限値及び下限値と、Ａｄｄ光の光レベル上限値及び下限値とを算出する。
【００７２】
そして、ＰＤ１７ｆのモニタ値をもとに、Ｔｈｒｕ光の光レベル推定値及びＡｄｄ光の光レベル推定値を求め、Ｔｈｒｕ光の光レベル推定値が、算出したＴｈｒｕ光の上限値と下限値の範囲内に収まるように、かつＡｄｄ光の光レベル推定値が、算出したＡｄｄ光の上限値と下限値の範囲内に収まるように、光レベルの調整制御を行う。
【００７３】
具体例で説明する。最初に初期条件として、ポストアンプ１２に入力される光レベルの上限値を１００、ポストアンプ１２に入力される光レベルの下限値を８０とし、Ｔｈｒｕ光の波長数を１５、Ａｄｄ光の波長数を５とする。また、ポストアンプ１２に現在入力されている光レベルを１２０とする（ＰＤ１７ｆによるモニタ結果により）。
【００７４】
まず、ポストアンプ１２の入力上限値が１００、Ｔｈｒｕ光の波長数が１５、Ａｄｄ光波長数が５であるため、Ｔｈｒｕ光の上限値＝１００＊（１５／（１５＋５））＝７５となり、Ａｄｄ光の上限値＝１００＊（１／（１５＋５））＝５となる。同様に下限値については、Ｔｈｒｕ光の下限値＝８０＊（１５／（１５＋５））＝６０となり、Ａｄｄ光の下限値＝８０＊（１／（１５＋５））＝４となる。
【００７５】
また、ＰＤ１７ｆで測定したポストアンプ１２への入力が１２０であるためＴｈｒｕ光の推定光レベルは波長数の比より、Ｔｈｒｕ光の推定値Ｍ６ａ＝１２０＊（１５／（１５＋５））＝９０と求まる。同様にＡｄｄ光の推定値に対しても、Ａｄｄ光の推定値Ｍ６ｂ＝１２０＊（１／（１５＋５））＝４と求まる。
【００７６】
そして、Ｔｈｒｕ光の推定値Ｍ６ａが、６０≦Ｍ６ａ≦７５になるようにＶＡＴＴ１４に対して制御信号を送出して調節する。同様に、Ａｄｄ光の推定値Ｍ６ｂが４≦Ｍ６ｂ≦５になるようにＶＡＴＴ１５に対して制御信号を送出して調節する。
【００７７】
このような光レベル調整制御を行うことで、光合波部１６で合波される光信号を、ポストアンプ１２で規定される入力範囲内であり、かつ各波長の光レベルを一定となるようにすることができる。
【００７８】
次に光伝送装置１０ａ−２における光レベル調整制御について詳細なフローチャートを用いて説明する。図１８〜図２０は第２の実施の形態の光レベル調整制御のフローチャートを示す図である。なお、各ステップの動作はすべてＮＥＭ１８ｂ（光レベル調整制御部１８）の動作である。ステップＳ１１７〜ステップＳ１３０はＶＡＴＴ１５（ｎ）の光レベル調整制御であり（ｎ回繰り返す）、ステップＳ１３１〜ステップＳ１４４はＶＡＴＴ１４の光レベル調整制御である。
〔Ｓ１１１〕ポストアンプ１２で規定されている入力レベル上限値（Ｐmax）と入力レベル下限値（Ｐmin）を取得する。
〔Ｓ１１２〕ポストアンプ１２で規定されている入力レベル上限値のマージンと入力レベル下限値のマージンを取得する。ここでは、双方のマージンを共にαとする。
〔Ｓ１１３〕実質的なポストアンプ１２の光レベル上限値（＝Ｐmax−α）と光レベル下限値（＝Ｐmin＋α）を算出する。
〔Ｓ１１４〕Ｔｈｒｕ光とＡｄｄ光の波長数比により、Ｔｈｒｕ光の上限値（Ｐmax thru）と下限値（Ｐmin thru）を上述の式（３ａ）、（３ｂ）で算出し、Ａｄｄ光の上限値（Ｐmax add）と下限値（Ｐmin add）を以下の式（３ｃ）、（３ｄ）で算出する。
〔Ｓ１１５〕ＰＤ１７ｆからモニタ値（Ｐall）を取得する。
〔Ｓ１１６〕Ｔｈｒｕ光のレベル推定値（Ｐguthru）とＡｄｄ光のレベル推定値（Ｐguadd）を以下の式で求める。
【００７９】
【数４】
Ｐguthru＝（Wno thru／Wno all）・（Ｐall） （４ａ）
Ｐguadd＝（１／Wno all）・（Ｐall） （４ｂ）
〔Ｓ１１７〕Ａｄｄ光のレベル推定値は、ステップＳ１１４で求めた下限値から上限値までの範囲以内か否かを判断する。下限値から上限値までの範囲より低い場合はステップＳ１１８へ、高い場合はステップＳ１２５へ、範囲以内ならステップＳ１３１へいく。
〔Ｓ１１８〕期待増加値（Ｐexadd inc）を算出する。期待増加値とは、下限値に対してどれだけレベルを増加させるかの値である。したがって、Ｐexadd inc＝Ｐmin add−Ｐguaddとなる。
〔Ｓ１１９〕ＶＡＴＴ１５（ｎ）の減衰度がゼロか否かを判断する（ゼロならステップＳ１２０へ、そうでなければステップＳ１２１へいく。すなわち、まったく減衰させていない場合はステップＳ１２０へ、減衰度が設定されている場合は、ステップＳ１２１へいく。
〔Ｓ１２０〕ＶＡＴＴ１５（ｎ）の下限アラームを発生する（これ以上、光レベルを上げられないので）。
〔Ｓ１２１〕下限アラームが発生中か否かを判断する。発生中ならステップＳ１２２へ、そうでなければステップＳ１２３へいく。
〔Ｓ１２２〕ＶＡＴＴ１５（ｎ）の下限アラームを回復する。
〔Ｓ１２３〕ＶＡＴＴ１５（ｎ）の減衰を弱める（光レベルを上げる）。
〔Ｓ１２４〕ＰＤ１７ｆからモニタ値を取得する。そして、ステップＳ１１６へ戻りＡｄｄ光のレベル推定値を再び算出される。
〔Ｓ１２５〕期待減衰値（Ｐexadd dec）を算出する。期待減衰値とは、上限値に対してどれだけレベルを減衰させるかの値である。したがって、Ｐexadd dec＝Ｐguadd−Ｐmax addとなる。
〔Ｓ１２６〕ＶＡＴＴ１５（ｎ）の減衰度が最大か否かを判断する。最大ならステップＳ１２７へ、そうでなければステップＳ１２８へいく。
〔Ｓ１２７〕ＶＡＴＴ１５（ｎ）の上限アラームを発生する（これ以上、光レベルを下げられないので）。
〔Ｓ１２８〕上限アラームが発生中か否かを判断する。発生中ならステップＳ１２９へ、そうでなければステップＳ１３０へいく。
〔Ｓ１２９〕ＶＡＴＴ１５（ｎ）の上限アラームを回復する。
〔Ｓ１３０〕ＶＡＴＴ１５（ｎ）の減衰を強める（光レベルを下げる）。そして、ステップＳ１２４へいく。
〔Ｓ１３１〕Ｔｈｒｕ光のレベル推定値は、ステップＳ１１４で求めた下限値から上限値までの範囲以内か否かを判断する。下限値から上限値までの範囲より低い場合はステップＳ１３２へ、高い場合はステップＳ１２５へ、範囲以内ならステップＳ１１１へいく。
〔Ｓ１３２〕期待増加値（Ｐexthru inc）を算出する。Ｐexthru inc＝Ｐmin thru−Ｐguthruである。
〔Ｓ１３３〕ＶＡＴＴ１４の減衰度がゼロか否かを判断する（ゼロならステップＳ１３４へ、そうでなければステップＳ１３５へいく。すなわち、まったく減衰させていない場合はステップＳ１３４へ、減衰度が設定されている場合は、ステップＳ１３５へいく。
〔Ｓ１３４〕ＶＡＴＴ１４の下限アラームを発生する（これ以上、光レベルを上げられないので）。
〔Ｓ１３５〕下限アラームが発生中か否かを判断する。発生中ならステップＳ１３６へ、そうでなければステップＳ１３７へいく。
〔Ｓ１３６〕ＶＡＴＴ１４の下限アラームを回復する。
〔Ｓ１３７〕ＶＡＴＴ１４の減衰を弱める（光レベルを上げる）。
〔Ｓ１３８〕ＰＤ１７ｆからモニタ値を取得する。そして、ステップＳ１１６へ戻りＴｈｒｕ光のレベル推定値を再び算出される。
〔Ｓ１３９〕期待減衰値（Ｐexthru dec）を算出する。Ｐexthru dec＝Ｐguthru−Ｐmax thruである。
〔Ｓ１４０〕ＶＡＴＴ１４の減衰度が最大か否かを判断する。最大ならステップＳ１４１へ、そうでなければステップＳ１４２へいく。
〔Ｓ１４１〕ＶＡＴＴ１４の上限アラームを発生する（これ以上、光レベルを下げられないので）。
〔Ｓ１４２〕上限アラームが発生中か否かを判断する。発生中ならステップＳ４３へ、そうでなければステップＳ１４４へいく。
〔Ｓ１４３〕ＶＡＴＴ１４の上限アラームを回復する。
〔Ｓ１４４〕ＶＡＴＴ１４の減衰を強める（光レベルを下げる）。そして、ステップＳ１３８へいく。
【００８０】
以上説明したように、本発明によれば、完全に波長分離させた後の全波長に対してＶＡＴＴによる減衰、ＰＤによるモニタを行うのではなく、多重化されたままで一括して減衰、モニタする。これにより、システムの全中継局において、ＶＡＴＴ／ＰＤを用意するためのコストを削減することが可能となる。
【００８１】
また、前局からの光信号を受光する装置と次局へ光信号を送信する装置を一体化させることで、装置構成の簡略化が実現できる。これにより、ファイバ接続数が減少するため、保守者の作業負担が軽減される。また、人為的なミスが減少し、信頼性の向上につながる。さらに、ＶＡＴＴによる光レベル調整を自動的に行うことができるので、運用効率及び利便性の向上を図ることが可能になる。
【００８２】
（付記１） ＷＤＭの光伝送を行う光伝送装置において、
前局からの光信号を受信し増幅するプリアンプと、
合波された光信号を増幅し、次局へ送信するポストアンプと、
前記プリアンプで増幅後の光信号を、Ｔｈｒｕ光とＤｒｏｐ光とに分岐する光分岐部と、
制御信号にもとづいて、波長多重されているＴｈｒｕ光の光レベルを一括して調整する第１の光可変減衰器と、
制御信号にもとづいて、波長多重後のＡｄｄ光の光レベルを一括して調整する第２の光可変減衰器と、
前記第１の光可変減衰器及び前記第２の光可変減衰器から出力された後の光信号を合波する光合波部と、
前記第１の光可変減衰器及び前記第２の光可変減衰器から出力される光信号をモニタする光モニタ部と、
モニタ結果にもとづいて、前記ポストアンプの入力レベル範囲内で、かつ各波長の光レベルがすべて同一値となるように、前記制御信号を生成して、前記第１の光可変減衰器及び前記第２の光可変減衰器の光レベルの調整制御を行う光レベル調整制御部と、
を有することを特徴とする光伝送装置。
【００８３】
（付記２） 前記光モニタ部は、前記第１の光可変減衰器の出力をモニタする第１のモニタ部と、前記第２の光可変減衰器の出力をモニタする第２のモニタ部と、から構成されることを特徴とする付記１記載の光伝送装置。
【００８４】
（付記３） 前記光レベル調整制御部は、前記ポストアンプで規定された光レベルの上限値と下限値をもとに、Ｔｈｒｕ光とＡｄｄ光それぞれの波長数比から、Ｔｈｒｕ光の光レベル上限値及び下限値と、Ａｄｄ光の光レベル上限値及び下限値とを算出し、前記第１のモニタ部によるモニタ値が、算出したＴｈｒｕ光の上限値と下限値の範囲内に収まるように、かつ前記第２のモニタ部によるモニタ値が、算出したＡｄｄ光の上限値と下限値の範囲内に収まるように、光レベルの調整制御を行うことを特徴とする付記２記載の光伝送装置。
【００８５】
（付記４） 前記光モニタ部は、前記光合波部の出力をモニタすることを特徴とする付記１記載の光伝送装置。
（付記５） 前記光レベル調整制御部は、前記第１の光可変減衰器または前記第２の光可変減衰器のいずれか一方の減衰制御幅を固定値とし、他方の減衰制御幅をＴｈｒｕ光とＡｄｄ光それぞれの波長数比から決定して、前記光モニタ部のモニタ値が、前記ポストアンプで規定された光レベルの上限値と下限値の範囲内に収まるように、双方の減衰制御幅を動かして、光レベルの調整制御を行うことを特徴とする付記４記載の光伝送装置。
【００８６】
（付記６） 前記光レベル調整制御部は、前記第１の光可変減衰器または前記第２の光可変減衰器の減衰度を最大減衰度に設定したにもかかわらず、前記ポストアンプへの入力光レベルが上限値を上回る場合、または最小減衰度に設定したにもかかわらず前記ポストアンプへの入力光が下限値を下回る場合には、アラームを発出し、アラーム発出後、前記ポストアンプへの入力光レベルが上限値と下限値内に収まった際は、アラーム回復を通知することを特徴とする付記１記載の光伝送装置。
【００８７】
（付記７） ＷＤＭの光伝送を行う光伝送装置において、
前局からの光信号を受信し増幅するプリアンプと、
合波された光信号を増幅し、次局へ送信するポストアンプと、
前記プリアンプで増幅後の光信号を、Ｔｈｒｕ光とＤｒｏｐ光とに分岐する光分岐部と、
制御信号にもとづいて、波長多重されているＴｈｒｕ光の光レベルを一括して調整する第１の光可変減衰器と、
制御信号にもとづいて、波長多重前の各Ａｄｄ光の光レベルを個別に調整する第２の光可変減衰器と、
前記第１の光可変減衰器から出力される光信号と、前記第２の光可変減衰器から出力され波長多重された後の光信号とを合波する光合波部と、
前記第１の光可変減衰器及び前記第２の光可変減衰器から出力された後の光信号をモニタする光モニタ部と、
モニタ結果にもとづいて、前記ポストアンプの入力レベル範囲内で、かつ各波長の光レベルがすべて同一値となるように、前記制御信号を生成して、前記第１の光可変減衰器及び第２の光可変減衰器の光レベルの調整制御を行う光レベル調整制御部と、
を有することを特徴とする光伝送装置。
【００８８】
（付記８） 前記光モニタ部は、前記第１の光可変減衰器の出力をモニタする第１のモニタ部と、前記第２の光可変減衰器の出力をモニタする第２のモニタ部と、から構成されることを特徴とする付記７記載の光伝送装置。
【００８９】
（付記９） 前記光レベル調整制御部は、前記ポストアンプで規定された光レベルの上限値と下限値をもとに、Ｔｈｒｕ光とＡｄｄ光それぞれの波長数比から、Ｔｈｒｕ光の光レベル上限値及び下限値と、Ａｄｄ光の光レベル上限値及び下限値とを算出し、前記第１のモニタ部によるモニタ値が、算出したＴｈｒｕ光の上限値と下限値の範囲内に収まるように、かつ前記第２のモニタ部によるモニタ値が、算出したＡｄｄ光の上限値と下限値の範囲内に収まるように、光レベルの調整制御を行うことを特徴とする付記８記載の光伝送装置。
【００９０】
（付記１０） 前記光モニタ部は、前記光合波部の出力をモニタすることを特徴とする付記７記載の光伝送装置。
（付記１１） 前記光レベル調整制御部は、前記ポストアンプで規定された光レベルの上限値と下限値をもとに、Ｔｈｒｕ光とＡｄｄ光それぞれの波長数比から、Ｔｈｒｕ光の光レベル上限値及び下限値と、Ａｄｄ光の光レベル上限値及び下限値とを算出し、前記光モニタ部のモニタ値をもとに、Ｔｈｒｕ光の光レベル推定値及びＡｄｄ光の光レベル推定値を求め、Ｔｈｒｕ光の光レベル推定値が、算出したＴｈｒｕ光の上限値と下限値の範囲内に収まるように、かつＡｄｄ光の光レベル推定値が、算出したＡｄｄ光の上限値と下限値の範囲内に収まるように、光レベルの調整制御を行うことを特徴とする付記１０記載の光伝送装置。
【００９１】
（付記１２） 前記光レベル調整制御部は、前記第１の光可変減衰器または前記第２の光可変減衰器の減衰度を最大減衰度に設定したにもかかわらず、前記ポストアンプへの入力光レベルが上限値を上回る場合、または最小減衰度に設定したにもかかわらず前記ポストアンプへの入力光が下限値を下回る場合には、アラームを発出し、アラーム発出後、前記ポストアンプへの入力光レベルが上限値と下限値内に収まった際は、アラーム回復を通知することを特徴とする付記７記載の光伝送装置。
【００９２】
（付記１３） ＷＤＭ伝送時の光信号の光レベルを調整する光レベル調整方法において、
前局からの光信号をプリアンプで受信して増幅した後の光信号を、Ｔｈｒｕ光とＤｒｏｐ光とに分岐し、
制御信号にもとづいて、波長多重されているＴｈｒｕ光の光レベルを第１の光可変減衰器で一括して調整し、
制御信号にもとづいて、波長多重後のＡｄｄ光の光レベルを第２の光可変減衰器で一括して調整し、
前記第１の光可変減衰器及び前記第２の光可変減衰器から出力される光信号を合波し、
前記第１の光可変減衰器及び前記第２の光可変減衰器から出力された後の光信号をモニタし、
合波された光信号を増幅して次局へ送信するためのポストアンプに対し、前記ポストアンプの入力レベル範囲内で、かつ各波長の光レベルがすべて同一値となるように、モニタ結果にもとづいて前記制御信号を生成して、前記第１の光可変減衰器及び前記第２の光可変減衰器の光レベルの調整制御を行うことを特徴とする光レベル調整方法。
【００９３】
（付記１４） 前記ポストアンプで規定された光レベルの上限値と下限値をもとに、Ｔｈｒｕ光とＡｄｄ光それぞれの波長数比から、Ｔｈｒｕ光の光レベル上限値及び下限値と、Ａｄｄ光の光レベル上限値及び下限値とを算出し、前記第１の光可変減衰器の出力をモニタしたモニタ値が、算出したＴｈｒｕ光の上限値と下限値の範囲内に収まるように、かつ前記第２の光可変減衰器の出力をモニタしたモニタ値が、算出したＡｄｄ光の上限値と下限値の範囲内に収まるように、光レベルの調整制御を行うことを特徴とする付記１３記載の光レベル調整方法。
【００９４】
（付記１５） 前記第１の光可変減衰器または前記第２の光可変減衰器のいずれか一方の減衰制御幅を固定値とし、他方の減衰制御幅をＴｈｒｕ光とＡｄｄ光それぞれの波長数比から決定して、合波後の出力信号をモニタしたモニタ値が、前記ポストアンプで規定された光レベルの上限値と下限値の範囲内に収まるように、双方の減衰制御幅を動かして、光レベルの調整制御を行うことを特徴とする付記１３記載の光レベル調整方法。
【００９５】
（付記１６） 前記第１の光可変減衰器または前記第２の光可変減衰器の減衰度を最大減衰度に設定したにもかかわらず、前記ポストアンプへの入力光レベルが上限値を上回る場合、または最小減衰度に設定したにもかかわらず前記ポストアンプへの入力光が下限値を下回る場合には、アラームを発出し、アラーム発出後、前記ポストアンプへの入力光レベルが上限値と下限値内に収まった際は、アラーム回復を通知することを特徴とする付記１３記載の光レベル調整方法。
【００９６】
（付記１７） ＷＤＭ伝送時の光信号の光レベルを調整する光レベル調整方法において、
前局からの光信号をプリアンプで受信して増幅した後の光信号を、Ｔｈｒｕ光とＤｒｏｐ光とに分岐し、
制御信号にもとづいて、波長多重されているＴｈｒｕ光の光レベルを第１の光可変減衰器で一括して調整し、
制御信号にもとづいて、波長多重前の各Ａｄｄ光の光レベルを第２の光可変減衰器で個別に調整し、
前記第１の光可変減衰器から出力される光信号と、前記第２の光可変減衰器から出力され波長多重された後の光信号とを合波し、
前記第１の光可変減衰器及び前記第２の光可変減衰器から出力された後の光信号をモニタし、
合波された光信号を増幅して次局へ送信するためのポストアンプに対し、前記ポストアンプの入力レベル範囲内で、かつ各波長の光レベルがすべて同一値となるように、モニタ結果にもとづいて前記制御信号を生成して、前記第１の光可変減衰器及び前記第２の光可変減衰器の光レベルの調整制御を行うことを特徴とする光レベル調整方法。
【００９７】
（付記１８） 前記ポストアンプで規定された光レベルの上限値と下限値をもとに、Ｔｈｒｕ光とＡｄｄ光それぞれの波長数比から、Ｔｈｒｕ光の光レベル上限値及び下限値と、Ａｄｄ光の光レベル上限値及び下限値とを算出し、前記第１の光可変減衰器の出力をモニタしたモニタ値が、算出したＴｈｒｕ光の上限値と下限値の範囲内に収まるように、かつ前記第２の光可変減衰器の出力をモニタしたモニタ値が、算出したＡｄｄ光の上限値と下限値の範囲内に収まるように、光レベルの調整制御を行うことを特徴とする付記１７記載の光レベル調整方法。
【００９８】
（付記１９） 前記ポストアンプで規定された光レベルの上限値と下限値をもとに、Ｔｈｒｕ光とＡｄｄ光それぞれの波長数比から、Ｔｈｒｕ光の光レベル上限値及び下限値と、Ａｄｄ光の光レベル上限値及び下限値とを算出し、合波後の出力信号をモニタしたモニタ値をもとに、Ｔｈｒｕ光の光レベル推定値及びＡｄｄ光の光レベル推定値を求め、Ｔｈｒｕ光の光レベル推定値が、算出したＴｈｒｕ光の上限値と下限値の範囲内に収まるように、かつＡｄｄ光の光レベル推定値が、算出したＡｄｄ光の上限値と下限値の範囲内に収まるように、光レベルの調整制御を行うことを特徴とする付記１７記載の光レベル調整方法。
【００９９】
（付記２０） 前記第１の光可変減衰器または前記第２の光可変減衰器の減衰度を最大減衰度に設定したにもかかわらず、前記ポストアンプへの入力光レベルが上限値を上回る場合、または最小減衰度に設定したにもかかわらず前記ポストアンプへの入力光が下限値を下回る場合には、アラームを発出し、アラーム発出後、前記ポストアンプへの入力光レベルが上限値と下限値内に収まった際は、アラーム回復を通知することを特徴とする付記１７記載の光レベル調整方法。
【０１００】
【発明の効果】
以上説明したように、光伝送装置は、ポストアンプの入力レベル範囲内で、かつ各波長の光レベルがすべて同一値となるように、モニタ結果にもとづき制御信号を生成して、すべてのＴｈｒｕ光の光レベルを一括して調整する第１の光可変減衰器及び波長多重後のすべてのＡｄｄ光の光レベルを一括して調整する第２の光可変減衰器の光レベルの調整制御を行う構成とした。これにより、高品質な光レベル調整制御を行うことができるので、装置規模を削減し、光伝送の品質及び信頼性の向上を図ることが可能になる。
また、Ｔｈｒｕ光の光レベルを調整する第１の光可変減衰器及びＡｄｄ光の光レベルを調整する第２の光可変減衰器のいずれか一方の減衰制御幅を固定値とし、他方の減衰制御幅をＴｈｒｕ光とＡｄｄ光それぞれの波長数比から決定して、Ｔｈｒｕ光とＡｄｄ光との合波部の後段に配置した光モニタ部のモニタ値が、ポストアンプで規定された光レベルの上限値と下限値の範囲内に収まるように、双方を減衰制御幅ずつ制御して、光レベルの調整制御を行う構成とした。これにより、高品質な光レベル調整制御を行うことができるので、装置規模を削減し、光伝送の品質及び信頼性の向上を図ることが可能になる。
【図面の簡単な説明】
【図１】 光伝送装置の原理図である。
【図２】光伝送装置の第１の実施の形態の構成を示す図である。
【図３】第１の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図４】第１の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図５】第１の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図６】第１の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図７】第１の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図８】光伝送装置の第２の実施の形態の構成を示す図である。
【図９】第２の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図１０】第２の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図１１】第２の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図１２】 光伝送装置の原理図である。
【図１３】光伝送装置の第１の実施の形態の構成を示す図である。
【図１４】第１の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図１５】第１の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図１６】第１の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図１７】光伝送装置の第２の実施の形態の構成を示す図である。
【図１８】第２の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図１９】第２の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図２０】第２の実施の形態の光レベル調整制御のフローチャートを示す図である。
【図２１】従来のＷＤＭ装置の構成を示す図である。
【符号の説明】
１０ 光伝送装置
１１ プリアンプ
１２ ポストアンプ
１３ 光分岐部
１３ａ 光カプラ
１３ｂ ＤＭＵＸ
１４ 第１の光可変減衰器
１５ 第２の光可変減衰器
１６ 光合波部
１７ 光モニタ部
１８ 光レベル調整制御部
１９ ＭＵＸ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical transmission apparatus, and more particularly to an optical transmission apparatus that performs WDM (Wavelength Division Multiplexing) optical transmission.
[0002]
[Prior art]
The optical communication network is the core of the foundation of the information communication network, and further advancement of service and wider area are desired, and development is progressing rapidly toward the information society. WDM technology is widely used as the central technology of optical transmission systems. WDM is a system in which light of different wavelengths is multiplexed and a plurality of signals are transmitted simultaneously using a single optical fiber.
[0003]
In addition, a node (device) that performs WDM transmission does not convert an optical signal into an electrical signal, but drops (adds) or inserts (adds) an optical signal having a specific wavelength. ) Is controlled.
[0004]
FIG. 21 is a diagram showing a configuration of a conventional WDM apparatus. Each relay station constituting the system is composed of a plurality of devices (for example, in the B station, the WDM devices 110-1 and 110-2 and the transponder TP).
[0005]
For station B, the WDM apparatus 110-1 includes a preamplifier 111 and a DMUX 112, and the WDM apparatus 110-2 includes optical variable attenuators (VATTs) 113-1 to 113-n, a MUX 114, and a post amplifier 115. Including. Note that only the post-amplifier 215 is described for the components in the WDM apparatus 210-2 of the A station, and only the preamplifier 311 is illustrated for the components in the WDM apparatus 310-1 of the C station.
[0006]
In the adjacent A station, B station, and C station, an optical signal output from the post-amplifier (PostAmp) 215 in the WDM apparatus 210-2 of the A station to the B station is transmitted through an optical transmission path (optical fiber) F10. And input to a preamplifier 111 in the WDM apparatus 110-1 of the B station.
[0007]
The optical signal amplified by the preamplifier 111 is separated into optical signals for each wavelength by the DMUX 112 and is Thru or Dropped. The optical signal transmitted through the optical transmission line F11 is wavelength-converted by a transponder TP that performs band conversion, and then transmitted to a low-speed network through the optical transmission line F12 (Drop).
[0008]
On the other hand, the optical signal transmitted through the optical transmission line F13 is input to the WDM device 110-2 (Thru). The optical signal transmitted from the low-speed network through the optical transmission path F14 is wavelength-converted by the transponder TP and then input to the WDM apparatus 110-2 through the optical transmission path F15 (Add).
[0009]
The Thru wavelength and Add wavelength are level-adjusted for each wavelength by a variable variable attenuator (VATT) 113-1 to 113-n in the WDM device 110-2, and wavelength-multiplexed by the MUX 114. The Then, the signal is amplified by the postamplifier 115 and transmitted to the preamplifier 311 of the WDM apparatus 310-1 at station C via the optical transmission line F16.
[0010]
Generally, in an WDM apparatus, when transmitting an optical signal to an adjacent station, the optical level is within the input range defined by the post-amplifier, and the optical level of each wavelength is constant (the optical levels of λ1 to λn are all the same level). Value), it is necessary to input to the post amplifier. For this reason, in the case of FIG. 21, VATTs 113-1 to 113-n are provided in the input range defined by the post-amplifier 115 and all the light levels of the respective wavelengths have the same value, and the MUX 114 has a wavelength. Prior to multiplexing, level adjustment is performed on the Thru light and Add light.
[0011]
As a conventional technique related to such an OADM for WDM transmission, there has been proposed a device for adjusting an attenuation amount of an output light from an optical transmitter by providing an optical variable attenuator so as to be equal to an optical level of a passing light. (For example, Patent Document 1).
[0012]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-186085 (paragraph numbers [0008] to [0012], FIG. 1)
[0013]
[Problems to be solved by the invention]
However, in the conventional WDM apparatus described above with reference to FIG. 21, it is necessary to reconnect fibers when performing path selection (Thru / Add / Drop) within a station. That is, it is necessary for the operator to manually change the optical fibers F11, F13, and F15. For this reason, there is a problem that a lot of burden is imposed on the operator and that an artificial connection error may occur.
[0014]
In addition, since VATTs 113-1 to 113-n are provided and level adjustment is performed for all wavelengths of Thru light and Add light after complete wavelength separation, the cost increases and the scale of the apparatus increases. There was a problem such as.
[0015]
Further, in both of the WDM apparatus shown in FIG. 21 and the prior art (Japanese Patent Laid-Open No. 2001-186085), when adjusting the optical level by VATT, the fiber is disconnected once and a spectrum analyzer is connected to each VATT. Had been adjusted. As described above, since the light level is manually adjusted, the efficiency is very poor, the convenience is lacking, and it is difficult to ensure reliability and quality.
[0016]
The present invention has been made in view of the above points, and automatically performs high-quality optical level adjustment control, thereby reducing the scale of the apparatus and improving the quality and reliability of optical transmission. An object is to provide an apparatus.
[0017]
[Means for Solving the Problems]
In the present invention, in order to solve the above-described problem, in an optical transmission apparatus 10 that performs WDM optical transmission as shown in FIG. 1, a preamplifier 11 that receives and amplifies an optical signal from the previous station, and combined light A post-amplifier 12 that amplifies the signal and transmits it to the next station, an optical branch 13 that branches the optical signal amplified by the pre-amplifier 11 into Thru light and Drop light, and wavelength-multiplexed based on the control signal First optical variable attenuator 14 that collectively adjusts the optical level of the Thru light, and second optical variable attenuator that collectively adjusts the optical level of Add light after wavelength multiplexing based on the control signal 15, an optical multiplexer 16 that combines optical signals output from the first optical variable attenuator 14 and the second optical variable attenuator 15, and the first optical variable attenuator 14 and the second optical variable attenuator. Monitors the optical signal output from the attenuator 15 Based on the optical monitor unit 17 and the monitoring result, a control signal is generated within the input level range of the post-amplifier 12 so that the optical levels of the respective wavelengths all have the same value, and the first optical variable There is provided an optical transmission device 10 including an optical level adjustment control unit 18 that performs optical level adjustment control of the attenuator 14 and the second optical variable attenuator 15.
[0018]
  Here, the preamplifier 11 receives and amplifies the optical signal from the previous station. The post amplifier 12 amplifies the combined optical signal and transmits it to the next station. The optical branching unit 13 branches the optical signal amplified by the preamplifier 11 into Thru light and Drop light. The first optical variable attenuator 14 collectively adjusts the optical level of the Thru light that is wavelength-multiplexed based on the control signal. The second optical variable attenuator 15 collectively adjusts the optical level of the Add light after wavelength multiplexing based on the control signal. The optical multiplexing unit 16 multiplexes the optical signals output from the first optical variable attenuator 14 and the second optical variable attenuator 15. The optical monitor unit 17 monitors optical signals output from the first optical variable attenuator 14 and the second optical variable attenuator 15. Based on the monitoring result, the light level adjustment control unit 18 generates a control signal within the input level range of the post-amplifier 12 so that the light levels of the respective wavelengths all have the same value, and outputs the first light. The optical level adjustment control of the variable attenuator 14 and the second optical variable attenuator 15 is performed.
  The optical monitor unit 17 includes a first monitor unit that monitors the output of the first optical variable attenuator 14 and a second monitor unit that monitors the output of the second optical variable attenuator 15. Then, the optical level adjustment control unit 18 determines the optical level upper limit value of the Thru light from the wavelength ratio of the Thru light and the Add light based on the upper limit value and the lower limit value of the optical level defined by the post-amplifier 12. The lower limit value, the upper limit value and the lower limit value of the light level of the Add light are calculated, and the second monitor value is within the range between the calculated upper limit value and lower limit value of the Thru light, and the second value. The light level adjustment control is performed so that the monitor value by the monitor unit falls within the range of the calculated upper limit value and lower limit value of the Add light.
[0019]
  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG.Is lightIt is a principle diagram of a transmission apparatus. The optical transmission device 10 is a device that performs WDM optical transmission.
[0020]
The preamplifier 11 receives and amplifies the optical signal (WDM signal) from the previous station. The post-amplifier 12 amplifies the optical signal (WDM signal) combined by the optical multiplexer 16 and transmits it to the next station.
[0021]
The optical branching unit 13 includes an optical coupler 13a and a DMUX 13b. The optical coupler 13a branches the optical signal amplified by the preamplifier 11 into Thru light and Drop light. The DMUX 13b wavelength-separates the Drop light and sends it to the low-speed network side.
[0022]
The first optical variable attenuator 14 (hereinafter referred to as VATT 14) collectively adjusts the optical level of the Thru light wavelength-multiplexed at the previous station based on a control signal from the optical level adjustment control unit 18. The MUX 19 wavelength-multiplexes the Add light from the low-speed network. The second optical variable attenuator 15 (hereinafter referred to as VATT 15) collectively adjusts the optical level of the Add light after being wavelength-multiplexed by the MUX 19 based on a control signal from the optical level adjustment control unit 18.
[0023]
The optical multiplexing unit (optical coupler) 16 multiplexes optical signals output from the VATT 14 and VATT 15. The optical monitor unit 17 monitors the optical signal output from the VATT 14 and VATT 15.
[0024]
Based on the monitor result, the optical level adjustment control unit 18 generates the above control signal so that the optical level of each wavelength is the same value within the input level range of the post-amplifier 12, and VATT 14 and Adjustment control of the light level of the VATT 15 is performed. The light level adjustment control unit 18 automatically performs light level adjustment control based on setting information from the operator. Also, alarm information to be described later is notified to the operator.
[0025]
  NextLightThe configuration and operation of the transmission apparatus 10 will be described in detail. FIG. 2 is a diagram illustrating the configuration of the first embodiment of the optical transmission apparatus 10. Each relay station that makes up the system,lightIt consists of a transmission device and a transponder. For example, the B station is composed of the optical transmission device 10-1 and the transponder TP (illustration of the transponders of the A station and the C station is omitted).
[0026]
For station B, the optical transmission device 10-1 includes a preamplifier 11, a post amplifier 12, an optical coupler 13a, a DMUX 13b, a VATT 14, a VATT 15, an optical multiplexing unit 16, PDs (Photo Diodes) 17a and 17b, and a network element management (NEM). 18a and MUX19. The PDs 17a and 17b correspond to the optical monitor unit 17 and are light receiving elements that perform optical / electrical conversion. The NEM 18a includes the function of the optical level adjustment control unit 18 and performs overall control of the optical transmission apparatus 10-1.
[0027]
Note that only the post-amplifier 22 is described for the components in the optical transmission apparatus 20-1 of the A station, and only the preamplifier 31 is shown for the components in the optical transmission apparatus 30-1 of the C station.
[0028]
In the adjacent A station, B station, and C station, the optical signal output from the post-amplifier 22 in the optical transmission device 20-1 of the A station to the B station is transmitted by the optical transmission path (optical fiber) F1, The signal is input to the preamplifier 11 in the optical transmission apparatus 10-1 of station B.
[0029]
The preamplifier 11 amplifies the optical signal, and the optical coupler 13a branches the amplified optical signal into Thru light and Drop light. The DMUX 13b separates the wavelength of the Drop light and sends it to the transponder TP through the optical transmission line F2. The optical signal transmitted through the optical transmission line F2 is wavelength-converted by a transponder TP that performs band conversion, and then transmitted to a low-speed network through the optical transmission line F3.
[0030]
The optical signal transmitted from the low-speed network through the optical transmission path F4 is wavelength-converted by the transponder TP and then input to the optical transmission apparatus 110-1 through the optical transmission path F5. The MUX 19 wavelength-multiplexes the Add light output from the transponder TP.
[0031]
On the other hand, the VATT 14 adjusts the light level of the Thru light based on the control signal. The VATT 15 adjusts the light level of the Add light based on the control signal. The optical multiplexing unit 16 combines the Thru light and the Add light after adjusting the optical level. The post amplifier 12 amplifies the combined optical signal. The amplified optical signal is transmitted to the preamplifier 31 of the optical transmission apparatus 30-1 at station C via the optical transmission path F6.
[0032]
On the other hand, the PD 17a monitors the optical level of the output signal (position P1) of the VATT 14 and transmits the monitoring result to the NEM 18a. The PD 17b monitors the optical level of the output signal (position P2) of the VATT 15 and transmits the monitoring result to the NEM 18a. Based on the monitor result, the NEM 18a sends a control signal to the VATTs 14 and 15 to perform light level adjustment control.
[0033]
Next, optical level adjustment control in the optical transmission apparatus 10-1 according to the first embodiment will be described. As the light level adjustment control here, based on the upper limit value and the lower limit value of the light level of the post-amplifier 12, the upper limit value and the lower limit value of the Thru light are calculated from the ratio of the wavelength numbers of the Thru light and the Add light. The upper and lower light level values of Add light are calculated.
[0034]
The monitor value by the PD 17a falls within the calculated upper limit value and lower limit value range of the Thru light, and the monitor value by the PD 17b falls within the calculated upper limit value and lower limit value range of the Add light. The light level is adjusted and controlled.
[0035]
A specific example will be described. First, as initial conditions, the upper limit value of the light level input to the post amplifier 12 is set to 100 (dBm), the lower limit value of the light level input to the post amplifier 12 is set to 80 (dBm), and the number of wavelengths of the Thru light is set. 15. The number of wavelengths of Add light is 5. The unit of the upper limit value, the lower limit value, and the monitor value is dBm, and the description of the unit is omitted in the following description.
[0036]
First, since the input upper limit value of the post amplifier 12 is 100, the number of wavelengths of Thru light is 15, and the number of wavelengths of Add light is 5, the upper limit value of Thru light is 100 * (15 / (15 + 5)) = 75. This value is the upper limit value at P1 in FIG. Further, the upper limit value of Add light = 100 * (5 / (15 + 5)) = 25, which is the upper limit value at P2 in FIG.
[0037]
Similarly, for the lower limit, the lower limit of Thru light = 80 * (15 / (15 + 5)) = 60, and this value is the lower limit for P1. Further, the lower limit value of Add light = 80 * (5 / (15 + 5)) = 20, and this value is the lower limit value in P2.
[0038]
The NEM 18a acquires the light level monitor value M1 from the PD 17a, and sends a control signal to the VATT 14 so that the monitor value satisfies 60 ≦ M1 ≦ 75. Similarly, the light level monitor value M2 from the PD 17b is acquired, and the control value is sent to the VATT 15 so that the monitor value satisfies 20 ≦ M2 ≦ 25.
[0039]
By performing such optical level adjustment control, the optical signal combined by the optical multiplexing unit 16 is within the input range defined by the postamplifier 12, and the optical levels of the respective wavelengths all have the same value. Can be. Also, since the device for receiving the optical signal from the previous station and the device for transmitting the optical signal to the next station are integrated, the device configuration is simplified and the number of fiber connections is reduced. For this reason, an operator's work burden is reduced and an artificial connection mistake can be reduced.
[0040]
Next, optical level adjustment control in the optical transmission apparatus 10-1 will be described using a detailed flowchart. 3 to 7 are flowcharts of the light level adjustment control according to the first embodiment. Note that the operations in each step are all performed by the NEM 18a (light level adjustment control unit 18).
[S1] It is determined whether or not the number of wavelengths of the Thru light entering the optical multiplexing unit 16 or the number of wavelengths of the Add light entering the optical multiplexing unit 16 has changed. If there is a change, go to step S6 if not going to step S2.
[S2] The input level upper limit value (Pamp defined by the post-amplifier 12) high) and input level lower limit (Pamp low).
[S3] Input level upper limit margin (Pamp) defined by the post-amplifier 12 high offset) and input level lower limit margin (Pamp low offset). The margin of the input level upper limit value is an offset value indicating how much extra power is allowed to operate with respect to the upper limit value of input light that can be operated by the post amplifier 12. Similarly, the margin of the input level lower limit value is an offset value indicating how much extra power is allowed to operate with respect to the lower limit value of the input light at which the post amplifier 12 can operate.
[S4] After multiplexing by the optical multiplexer 16, the optical level upper limit value Pall high and light level lower limit Pall Each low is calculated. Upper limit Pall high and lower limit Pall Low is calculated using the following formula.
[0041]
[Expression 1]
Pall high = (Pamp high)-(Pamp high offset) (1a)
Pall low = (Pamp low)-(Pamp low offset) (1b)
For example, the input level upper limit (Pamp high) is 100, margin (Pamp high When the offset is +5, the substantial upper limit of the light level (Pall high) is 95. The input level lower limit (Pamp low) is 60, margin (Pamp low When the offset is -5, the effective light level lower limit (Pall low) is 65. That is, the upper limit / lower limit range of the post-amplifier 12 which is an initial condition is 60-100 → 65-95.
[S5] The upper limit of Thru light (Pthru) is determined by the ratio of the number of wavelengths of Thru light and Add light. high) and lower limit (Pthru) low) is calculated by the following equations (2a) and (2b), and the upper limit value of Add light (Padd) high) and lower limit (Padd low) is calculated by the following equations (2c) and (2d). However, Wno thru is the number of wavelengths of the Thru light entering the optical multiplexing unit 16, Wno add is the number of wavelengths of Add light entering the optical multiplexing unit 16, and Wno all is the number of wavelengths multiplexed by the optical multiplexing unit 16 (Wno thru + Wno add).
[0042]
[Expression 2]

[S6] The monitor value PD1MON of the PD 17a and the monitor value PD2MON of the PD 17b are acquired.
[S7] PD1MON and Pthru Compare high. PD1MON> Pthru If high, go to step S8, PD1MON ≦ Pthru If high, go to step S13. That is, if the power of the Thru light exceeds the upper limit value, the process proceeds to step S8, and if not, the process proceeds to step S13.
[S8] The current attenuation setting value (Xvatt1) is compared with the maximum attenuation degree (Xvatt1max) of VATT14. If Xvatt1> Xvatt1max, go to step S9, and if Xvatt1 ≦ Xvatt1max, go to step S10. That is, if the controllable attenuation is exceeded, the process proceeds to step S9, and if within the control range, the process proceeds to step S10.
[S9] An upper limit alarm for VATT 14 is issued.
[S10] The upper limit alarm of VATT 14 disappears (notification of alarm recovery).
[S11] The attenuation is increased by setting Xvatt1 = Xvatt1 + Δ. Δ is an attenuation control width (step size) per unit step.
[S12] PD1MON is acquired, and the process returns to step S7.
[S13] PD1MON and Pthru Compare low. Pthru If low> PD1MON, go to step S14, Pthru If low ≦ PD1MON, go to step S19. That is, if the power of the Thru light is below the lower limit value, go to step S14, otherwise go to step S19.
[S14] The attenuation set value (Xvatt1) is compared with the minimum attenuation (Xvatt1min) of VATT14. If Xvatt1min> Xvatt1, go to step S15, and if Xvatt1min ≦ Xvatt1, go to step S16. That is, if it falls below the controllable attenuation, go to Step S15, and if it is within the control range, go to Step S16.
[S15] A lower limit alarm for VATT 14 is issued.
[S16] The lower limit alarm of VATT 14 disappears (alarm recovery notification).
[S17] The attenuation is loosened by setting Xvatt1 = Xvatt1-Δ.
[S18] PD1MON is acquired, and the process returns to step S13.
[S19] PD2MON and Padd Compare high. PD2MON> Padd If high, go to step S20, PD2MON ≦ Padd If high, go to step S25. That is, if the power of the Add light exceeds the upper limit value, the process proceeds to step S20, and if not, the process proceeds to step S25.
[S20] The attenuation set value (Xvatt2) is compared with the maximum attenuation (Xvatt2max) of VATT15. If Xvatt2> Xvatt2max, go to step S21, and if Xvatt2 ≦ Xvatt2max, go to step S22. That is, if the controllable attenuation is exceeded, the process proceeds to step S21, and if within the control range, the process proceeds to step S22.
[S21] An upper limit alarm for VATT 15 is issued.
[S22] The upper limit alarm of VATT 15 disappears (alarm recovery notification).
[S23] The attenuation is increased by setting Xvatt2 = Xvatt2 ++.
[S24] PD2MON is acquired, and the process returns to step S19.
[S25] PD2MON and Padd Compare low. Padd If low ≦ PD2MON, return to Step S1 and Padd If low> PD2MON, go to step S26. That is, when the power of the Add light does not fall below the lower limit value, the process goes to step S1, and when it falls below, the process goes to step S26.
[S26] The attenuation set value (Xvatt2) is compared with the minimum attenuation (Xvatt2min) of VATT15. If Xvatt2min> Xvatt2, go to step S27, and if Xvatt2min ≦ Xvatt2, go to step S28. That is, if it falls below the controllable attenuation, go to step S27, and if it is within the control range, go to step S28.
[S27] A lower limit alarm for VATT 15 is issued.
[S28] The lower limit alarm of VATT 15 disappears (alarm recovery notification).
[S29] The attenuation is loosened by setting Xvatt2 = Xvatt2-Δ.
[S30] Obtain PD2MON and return to step S25.
[0043]
Next, the configuration and operation of the optical transmission apparatus according to the second embodiment will be described in detail. FIG. 8 is a diagram illustrating the configuration of the second embodiment of the optical transmission apparatus 10. In the optical transmission apparatus 10-1 described above with reference to FIG. 2, the PDs 17a and 17b are configured to monitor the optical power at the output stage of the VATTs 14 and 15. However, in the optical transmission apparatus 10-2 of the second embodiment, A PD 17c is provided at the output stage of the optical multiplexing unit 16 to monitor the power of the combined optical signal. Since only this portion is different from the configuration of the first embodiment, description of other configurations is omitted.
[0044]
Next, optical level adjustment control in the optical transmission apparatus 10-2 according to the second embodiment will be described. As the light level adjustment control here, either one of the attenuation control widths of VATT 14 and VATT 15 is set to a fixed value, and the other attenuation control width is determined from the ratio of the number of wavelengths of the Thru light and the Add light.
[0045]
Then, both the attenuation control widths (calculated from the fixed attenuation control width and the ratio of the number of wavelengths) are set so that the monitor value of the PD 17c falls within the range of the upper limit value and the lower limit value of the light level defined by the postamplifier 12. Adjust the light level by moving the attenuation control width.
[0046]
A specific example will be described. First, as initial conditions, the upper limit value of the light level input to the post-amplifier 12 is set to 100, the lower limit value of the light level input to the post-amplifier 12 is set to 80, the number of wavelengths of Thru light is 15, and the number of wavelengths of Add light Is 5.
[0047]
The attenuation control width for increasing or decreasing the attenuation of VATT 14 is Δa, the attenuation control width for increasing or decreasing the attenuation of VATT 15 is Δb, Δa is a fixed value (= 1), and Δb is a wavelength ratio (5/15 = 1/3), the attenuation is controlled at a ratio of Δa: Δb = 1: 1/3. For example, if 2 control widths are moved by one adjustment operation of VATT 14, 2/3 (= 2 × (1/3)) control width is moved by one adjustment operation of VATT15.
[0048]
Then, the NEM 18a acquires the optical level monitor value M3 from the PD 17c, sends a control signal so that the monitor value M3 satisfies 80 ≦ M3 ≦ 100, and adjusts Δa for VATT14 and Δb for VATT15. To do. By performing such optical level adjustment control, the optical signal combined by the optical multiplexer 16 is within the input range defined by the post amplifier 12 and the optical level of each wavelength is constant. can do.
[0049]
Next, optical level adjustment control in the optical transmission apparatus 10-2 will be described using a detailed flowchart. 9 to 11 are flowcharts of the light level adjustment control according to the second embodiment. Note that the operations in each step are all performed by the NEM 18a (light level adjustment control unit 18).
[S41] It is determined whether the number of wavelengths of the Thru light entering the optical multiplexing unit 16 or the number of wavelengths of the Add light entering the optical multiplexing unit 16 has changed. If there is a change, go to step S42, otherwise go to step S46.
[S42] The input level upper limit value (Pamp) defined by the post-amplifier 12 high) and input level lower limit (Pamp low).
[S43] The margin of the input level upper limit value defined by the post-amplifier 12 (Pamp high offset) and input level lower limit margin (Pamp low offset).
[S44] After multiplexing by the optical multiplexing unit 16, the optical level upper limit value Pall high and light level lower limit Pall Each of low is calculated from the above formulas (1a) and (1b).
[S45] The attenuation control width Δa of the VATT 14 and the attenuation control width Δb of the VATT 15 are obtained from the wavelength number ratio of the Thru light and the Add light (for example, Δa is a fixed value, and Δb is a value obtained from the wavelength number ratio).
[S46] The monitor value PD3MON of the PD 17c is acquired.
[S47] PD3MON and Pall Compare high. PD3MON> Pall If high, go to step S48, PD3MON ≦ Pall If high, go to step S57. That is, if the combined light power exceeds the upper limit value, the process proceeds to step S48, and if not, the process proceeds to step S57.
[S48] The attenuation set value (Xvatt1) of the VATT 14 is compared with the maximum attenuation (Xvatt1max) of the VATT 14. If Xvatt1> Xvatt1max, go to step S49, and if Xvatt1 ≦ Xvatt1max, go to step S50. That is, if the controllable attenuation is exceeded, the process proceeds to step S49, and if within the control range, the process proceeds to step S50.
[S49] An upper limit alarm for VATT 14 is issued.
[S50] The upper limit alarm of VATT 14 disappears (alarm recovery notification).
[S51] The attenuation is increased by setting Xvatt1 = Xvatt1 + Δa.
[S52] The attenuation set value (Xvatt2) of VATT 15 is compared with the maximum attenuation (Xvatt2max) of VATT 15. If Xvatt2> Xvatt2max, go to step S53, and if Xvatt2 ≦ Xvatt2max, go to step S54. That is, if the controllable attenuation is exceeded, the process proceeds to step S53, and if within the control range, the process proceeds to step S54.
[S53] An upper limit alarm for VATT 15 is issued.
[S54] The upper limit alarm of VATT 15 disappears (alarm recovery notification).
[S55] The attenuation is increased by setting Xvatt2 = Xvatt2 + Δb.
[S56] PD3MON is acquired, and the process returns to step S47.
[S57] PD3MON and Pall Compare low. Pall If low> PD3MON, go to step S58, Pall If low ≦ PD3MON, the process returns to step S41. That is, if the power of the combined light is below the lower limit value, go to step S58, and if not, go to step S41.
[S58] The attenuation set value (Xvatt1) of VATT 14 is compared with the minimum attenuation (Xvatt1min) of VATT 14. If Xvatt1min> Xvatt1, the process proceeds to step S59, and if Xvatt1min ≦ Xvatt1, the process proceeds to step S60. That is, if it falls below the controllable attenuation, the process proceeds to step S59, and if within the control range, the process proceeds to step S60.
[S59] A VATT 14 lower limit alarm is issued.
[S60] The lower limit alarm of VATT 14 disappears (alarm recovery notification).
[S61] The attenuation is loosened by setting Xvatt1 = Xvatt1-Δa.
[S62] The attenuation set value (Xvatt2) of VATT 15 and the minimum attenuation (Xvatt2min) of VATT 15 are compared. If Xvatt2min> Xvatt2, go to step S63, and if Xvatt2min ≦ Xvatt2, go to step S64. That is, if the attenuation is less than the controllable attenuation, the process proceeds to step S63, and if within the control range, the process proceeds to step S64.
[S63] A VATT 15 lower limit alarm is issued.
[S64] The lower limit alarm of VATT 15 disappears (alarm recovery notification).
[S65] The attenuation is loosened by setting Xvatt2 = Xvatt2-Δb.
[S66] Obtain PD3MON and return to step S57.
[0050]
  Next, the principle configuration is different from that of the optical transmission apparatus 10 described above with reference to FIG.OtherThe optical transmission apparatus will be described. FIG.Is lightIt is a principle diagram of a transmission apparatus. In the optical transmission apparatus 10 described above with reference to FIG. 1, the VATT 14 is provided at the output stage from which the Thru light is output from the optical coupler 13a, and the VATT 15 is provided at the output stage of the MUX 19, so that the optical signals after being output from the VATTs 14 and 15 The power was monitored and light level adjustment control was performed.
[0051]
On the other hand, in the optical transmission apparatus 10a shown in FIG. 12, the VATT 14 is installed at the same position as in FIG. 1, but for the VATT 15, VATTs 15-1 to 15-n corresponding to the number of wavelengths are provided in the input stage of the MUX 19. . The optical level adjustment control is performed by monitoring the power of the optical signals output from the VATT 14 and VATTs 15-1 to 15-n. Since this is the only principle block that is different from the optical transmission apparatus 10, description of other principle blocks is omitted.
[0052]
  Next, the configuration and operation of the optical transmission device 10a will be described in detail. FIG. 13 is a diagram illustrating the configuration of the first embodiment of the optical transmission apparatus 10a. Each relay station that makes up the system,lightIt consists of a transmission device and a transponder. For example, the B station is composed of the optical transmission device 10a-1 and the transponder TP (illustration of the transponders of the A station and the C station is omitted).
[0053]
For the B station, the optical transmission device 10a-1 includes a preamplifier 11, a post amplifier 12, an optical coupler 13a, a DMUX 13b, a VATT 14, VATTs 15-1 to 15-n, an optical multiplexing unit 16, PD17d, PD17e-1 to 17e-n. , NEM18b, and MUX19. PDs 17d and 17e-1 to 17e-n correspond to the optical monitor unit 17, and are light receiving elements that perform optical / electrical conversion. The NEM 18b includes the function of the optical level adjustment control unit 18, and performs overall control of the optical transmission device 10a-1.
[0054]
Note that only the post-amplifier 22 is described for the components in the optical transmission device 20a-1 of the A station, and only the preamplifier 31 is illustrated for the components in the optical transmission device 30a-1 of the C station.
[0055]
In the adjacent A station, B station, and C station, the optical signal output from the post-amplifier 22 in the optical transmission device 20a-1 of the A station to the B station is transmitted through the optical transmission path (optical fiber) F1, The signal is input to the preamplifier 11 in the optical transmission apparatus 10a-1 of station B.
[0056]
The preamplifier 11 amplifies the optical signal, and the optical coupler 13a branches the amplified optical signal into Thru light and Drop light. The DMUX 13b separates the wavelength of the Drop light and sends it to the transponder TP through the optical transmission line F2. The optical signal transmitted through the optical transmission line F2 is wavelength-converted by a transponder TP that performs band conversion, and then transmitted to a low-speed network through the optical transmission line F3.
[0057]
The optical signal transmitted from the low-speed network through the optical transmission line F4 is wavelength-converted by the transponder TP and then input to the optical transmission device 10a-1 through the optical transmission line F5.
[0058]
On the other hand, the VATT 14 adjusts the light level of the Thru light based on the control signal. The VATTs 15-1 to 15-n individually adjust the light level of each Add light based on the control signal. The MUX 19 wavelength-multiplexes the Add light output from the VATTs 15-1 to 15-n. The optical multiplexing unit 16 combines the Thru light and the Add light after adjusting the optical level. The post amplifier 12 amplifies the combined optical signal. Then, the amplified optical signal is transmitted to the preamplifier 31 of the optical transmission device 30a-1 of the C station through the optical transmission path F6.
[0059]
On the other hand, the PD 17d monitors the optical level of the output signal of the VATT 14 and transmits the monitoring result to the NEM 18b. The PDs 17e-1 to 17-n monitor the optical levels of the output signals of the VATTs 15-1 to 15-n, and transmit the monitoring results to the NEM 18b. The NEM 18b performs light level adjustment control of the VATTs 14 and 15-1 to 15-n based on the monitor result.
[0060]
Next, optical level adjustment control in the optical transmission device 10a-1 according to the first embodiment will be described. The optical level adjustment control here is the same as the control of the optical transmission device 10-1. That is, based on the upper limit value and the lower limit value of the light level of the post-amplifier 12, the upper limit value and lower limit value of the Thru light and the upper limit value of the light level of the Thru light are obtained from the ratio of the wavelength numbers of the Thru light and the Add light. And a lower limit value are calculated.
[0061]
Then, the monitor values of PD 17d are within the range of the calculated upper and lower limits of the Thru light, and the monitor values of PD 17e-1 to 17e-n are the calculated upper and lower limits of Add light. Light level adjustment control is performed so as to be within the range of values.
[0062]
A specific example will be described. First, as initial conditions, the upper limit value of the light level input to the post-amplifier 12 is 100, the lower limit value of the light level input to the post-amplifier 12 is 80, the number of wavelengths of the Thru light is 15, and the wavelength of the Add light Let the number be 5.
[0063]
First, since the input upper limit value of the post amplifier 12 is 100, the number of wavelengths of Thru light is 15, and the number of wavelengths of Add light is 5, the upper limit value of Thru light is 100 * (15 / (15 + 5)) = 75. This value is the upper limit value at P4 in FIG. Further, the upper limit value of Add light = 100 * (1 / (15 + 5)) = 5, and this value is the upper limit value in P5-1 to P5-n in FIG. Note that 1 of 1 / (15 + 5) numerator is one wave input to each of VATTs 17e-1 to 17e-n.
[0064]
Similarly, for the lower limit, the lower limit of Thru light = 80 * (15 / (15 + 5)) = 60, and this value is the lower limit for P4. Also, the lower limit value of Add light = 80 * (1 / (15 + 5)) = 4, and this value is the lower limit value in P5-1 to P5-n.
[0065]
The NEM 18b acquires the light level monitor value M4 from the PD 17d, and adjusts the monitor value by sending a control signal to the VATT 14 so that the monitor value satisfies 60 ≦ M4 ≦ 75. Similarly, the optical level monitor values M5-1 and M5-n of the PDs 17e-1 to 17e-n are acquired, and the VATTs 15-1 to V5-1 are set so that the monitor values satisfy 4 ≦ M5-1,. Send control signal to 15-n to adjust.
[0066]
By performing such optical level adjustment control, the optical signal combined by the optical multiplexer 16 is within the input range defined by the post amplifier 12 and the optical level of each wavelength is constant. can do.
[0067]
Regarding the device scale, the optical transmission device 10a-1 has a larger number of VATTs and PDs than the optical transmission device 10-1 in FIG. 2, but is larger than the conventional device as described above with reference to FIG. The device scale can be reduced.
[0068]
Next, optical level adjustment control in the optical transmission device 10a-1 will be described using a detailed flowchart. 14 to 16 are flowcharts of the light level adjustment control according to the first embodiment. Note that the operations in each step are all performed by the NEM 18b (light level adjustment control unit 18). Steps S77 to S88 are light level adjustment control of VATT15-1 to VATT15-n (generally referred to as VATT15 (n)) (repeated n times), and steps S89 to S100 are light level adjustment control of VATT14. It is. Further, all the operations from step S71 to step S100 thereafter are basically the same as the above-described steps S1 to S30.
[S71] A monitor value of Thru light is acquired from the PD 17d.
[S72] Monitor values of Add light are acquired from the PDs 17e-1 to 17e-n.
[S73] An input level upper limit (Pmax) and an input level lower limit (Pmin) defined by the postamplifier 12 are acquired.
[S74] The input level upper limit margin and the input level lower limit margin defined by the post-amplifier 12 are acquired. Here, both margins are both α.
[S75] The substantial light level upper limit (= Pmax−α) and light level lower limit (= Pmin + α) of the post-amplifier 12 are calculated.
[S76] The upper limit value (Pmax thru) and lower limit value (Pmin thru) of the Thru light are calculated by the following equations (3a) and (3b) based on the ratio of the number of wavelengths of the Thru light and the Add light, and the upper limit value of the Add light. (Pmax add) and the lower limit (Pmin add) are calculated by the following equations (3c) and (3d).
[0069]
[Equation 3]

[S77] It is determined whether or not the monitor values obtained by PDs 17e-1 to 17e-n (collectively referred to as PD17e (n)) acquired in step S72 are within the range from the lower limit value to the upper limit value obtained in step S76. To do. If it is lower than the range from the lower limit value to the upper limit value, go to Step S77, if it is higher, go to Step S84, and if within the range, go to Step S89.
[S78] It is determined whether or not the attenuation of VATT15 (n) is zero (if zero, go to step S79, otherwise go to step S80. That is, if not attenuated at all, go to step S79. If set, go to step S80.
[S79] A lower limit alarm of VATT15 (n) is generated (because the light level cannot be increased any more).
[S80] It is determined whether a lower limit alarm is occurring. If it is occurring, go to step S81, otherwise go to step S82.
[S81] The lower limit alarm of VATT15 (n) is recovered.
[S82] Decrease the attenuation of VATT 15 (n) (increase the light level).
[S83] A monitor value is acquired from the PD 17e (n). Then, the process returns to step S77.
[S84] It is determined whether or not the attenuation of the VATT 15 (n) is maximum. If so, go to step S85, otherwise go to step S86.
[S85] An upper limit alarm of VATT15 (n) is generated (because the light level cannot be lowered any more).
[S86] It is determined whether an upper limit alarm is occurring. If it is occurring, go to step S87, otherwise go to step S88.
[S87] The upper limit alarm of VATT15 (n) is recovered.
[S88] The attenuation of VATT15 (n) is increased (the light level is lowered). Then, the process goes to step S83.
[S89] It is determined whether or not the monitor value obtained by the PD 17d acquired in step S71 is within the range from the lower limit value to the upper limit value obtained in step S76. If it is lower than the range from the lower limit value to the upper limit value, the process returns to step S90, if it is higher, the process returns to step S96, and if within the range, the process returns to step S71.
[S90] It is determined whether or not the attenuation of the VATT 14 is zero (if it is zero, go to step S91, otherwise go to step S92. In other words, if not attenuated at all, the attenuation is set to step S91. If yes, go to step S92.
[S91] A lower limit alarm for VATT 14 is generated (because the light level cannot be increased any more).
[S92] It is determined whether a lower limit alarm is occurring. If it is occurring, go to step S93, otherwise go to step S94.
[S93] The lower limit alarm of VATT14 is recovered.
[S94] Decrease the attenuation of the VATT 14 (increase the light level).
[S95] A monitor value is acquired from the PD 17d. Then, the process returns to step S89.
[S96] It is determined whether the attenuation of the VATT 14 is maximum. If so, go to Step S97, otherwise go to Step S98.
[S97] An upper limit alarm for VATT 14 is generated (because the light level cannot be lowered any more).
[S98] It is determined whether an upper limit alarm is occurring. If it is occurring, go to step S99, otherwise go to step S100.
[S99] The upper limit alarm of the VATT 14 is recovered.
[S100] The attenuation of VATT 14 is increased (the light level is lowered). Then, the process goes to step S95.
[0070]
Next, the configuration and operation of the optical transmission apparatus according to the second embodiment will be described in detail. FIG. 17 is a diagram illustrating the configuration of the second embodiment of the optical transmission apparatus 10a. In the optical transmission device 10a-1 described above with reference to FIG. 2, the PD 17d is monitored at the output stage of the VATT 14, and the PDes-1 to 17e-n are respectively monitored at the output stages of the VATTs 15-1 to 15-n. In the optical transmission device 10a-2 of the second embodiment, the PD 17f is provided at the output stage of the optical multiplexing unit 16 to monitor the power of the combined optical signal. Since only this portion is different from the configuration of the first embodiment, description of other configurations is omitted.
[0071]
Next, optical level adjustment control in the optical transmission device 10a-2 according to the second embodiment will be described. As the light level adjustment control here, based on the upper limit value and lower limit value of the light level defined by the post-amplifier 12, the upper limit value of the Thru light level and the ratio of the number of wavelengths of the Thru light and the Add light are determined. The lower limit value and the light level upper limit value and lower limit value of the Add light are calculated.
[0072]
Then, based on the monitor value of the PD 17f, the estimated light level of the Thru light and the estimated light level of the Add light are obtained, and the estimated light level of the Thru light is within the calculated upper and lower limits of the Thru light. The light level adjustment control is performed so that the estimated light level of the Add light falls within the range between the calculated upper limit value and lower limit value of the Add light.
[0073]
A specific example will be described. First, as initial conditions, the upper limit value of the light level input to the post-amplifier 12 is set to 100, the lower limit value of the light level input to the post-amplifier 12 is set to 80, the number of wavelengths of Thru light is 15, and the number of wavelengths of Add light Is 5. Further, the light level currently input to the postamplifier 12 is set to 120 (according to the monitoring result by the PD 17f).
[0074]
First, since the input upper limit value of the postamplifier 12 is 100, the number of wavelengths of Thru light is 15, and the number of wavelengths of Add light is 5, the upper limit value of Thru light = 100 * (15 / (15 + 5)) = 75. The upper limit value of light = 100 * (1 / (15 + 5)) = 5. Similarly, regarding the lower limit value, the lower limit value of Thru light = 80 * (15 / (15 + 5)) = 60, and the lower limit value of Add light = 80 * (1 / (15 + 5)) = 4.
[0075]
Further, since the input to the postamplifier 12 measured by the PD 17f is 120, the estimated light level of the Thru light is obtained as an estimated value of the Thru light M6a = 120 * (15 / (15 + 5)) = 90 from the ratio of the number of wavelengths. . Similarly, the estimated value of Add light M6b = 120 * (1 / (15 + 5)) = 4 is also obtained for the estimated value of Add light.
[0076]
Then, the control value is sent to the VATT 14 so that the estimated value M6a of the Thru light satisfies 60 ≦ M6a ≦ 75. Similarly, a control signal is sent to the VATT 15 so that the estimated value M6b of the Add light is 4 ≦ M6b ≦ 5.
[0077]
By performing such optical level adjustment control, the optical signal combined by the optical multiplexer 16 is within the input range defined by the post amplifier 12 and the optical level of each wavelength is constant. can do.
[0078]
Next, optical level adjustment control in the optical transmission device 10a-2 will be described using a detailed flowchart. 18 to 20 are flowcharts illustrating the light level adjustment control according to the second embodiment. Note that the operations in each step are all performed by the NEM 18b (light level adjustment control unit 18). Steps S117 to S130 are light level adjustment control of VATT15 (n) (repeated n times), and steps S131 to S144 are light level adjustment control of VATT14.
[S111] An input level upper limit value (Pmax) and an input level lower limit value (Pmin) defined by the postamplifier 12 are acquired.
[S112] The input level upper limit margin and the input level lower limit margin defined by the postamplifier 12 are acquired. Here, both margins are both α.
[S113] The substantial light level upper limit (= Pmax−α) and light level lower limit (= Pmin + α) of the post-amplifier 12 are calculated.
[S114] The upper limit value (Pmax thru) and lower limit value (Pmin thru) of the Thru light are calculated by the above formulas (3a) and (3b) based on the ratio of the number of wavelengths of the Thru light and the Add light, and the upper limit value of the Add light. (Pmax add) and the lower limit (Pmin add) are calculated by the following equations (3c) and (3d).
[S115] The monitor value (Pall) is acquired from the PD 17f.
[S116] The Thru light level estimation value (Pguthru) and the Add light level estimation value (Pguadd) are obtained by the following equations.
[0079]
[Expression 4]
Pguthru = (Wno thru / Wno all) ・ (Pall) (4a)
Pguadd = (1 / Wno all) ・ (Pall) (4b)
[S117] It is determined whether the estimated level of the Add light is within the range from the lower limit value to the upper limit value obtained in step S114. If it is lower than the range from the lower limit value to the upper limit value, go to Step S118, if it is higher, go to Step S125, and if it is within the range, go to Step S131.
[S118] An expected increase value (Pexadd inc) is calculated. The expected increase value is a value indicating how much the level is increased with respect to the lower limit value. Therefore, Pexadd inc = Pmin add−Pguadd.
[S119] It is determined whether or not the attenuation of VATT 15 (n) is zero (if it is zero, the process proceeds to step S120, otherwise the process proceeds to step S121. That is, if it is not attenuated at all, the process proceeds to step S120. If it is set, go to step S121.
[S120] A lower limit alarm of VATT15 (n) is generated (because the light level cannot be increased any more).
[S121] It is determined whether a lower limit alarm is occurring. If it is occurring, go to step S122, otherwise go to step S123.
[S122] The lower limit alarm of VATT15 (n) is recovered.
[S123] Decrease the attenuation of VATT15 (n) (increase the light level).
[S124] The monitor value is acquired from the PD 17f. Then, the process returns to step S116, and the level estimate value of the Add light is calculated again.
[S125] An expected attenuation value (Pexadd dec) is calculated. The expected attenuation value is a value indicating how much the level is attenuated with respect to the upper limit value. Therefore, Pexadd dec = Pguadd−Pmax add.
[S126] It is determined whether the attenuation of VATT 15 (n) is maximum. If so, go to Step S127, otherwise go to Step S128.
[S127] An upper limit alarm of VATT15 (n) is generated (because the light level cannot be lowered any more).
[S128] It is determined whether an upper limit alarm is occurring. If it is occurring, go to step S129, otherwise go to step S130.
[S129] The upper limit alarm of VATT15 (n) is recovered.
[S130] The attenuation of VATT 15 (n) is increased (the light level is lowered). Then, the process goes to step S124.
[S131] It is determined whether the estimated level of the Tru light is within the range from the lower limit value to the upper limit value obtained in step S114. If it is lower than the range from the lower limit value to the upper limit value, go to Step S132, if it is higher, go to Step S125, and if it is within the range, go to Step S111.
[S132] An expected increase value (Pexthru inc) is calculated. Pexthru inc = Pmin thru−Pguthru.
[S133] It is determined whether or not the attenuation of the VATT 14 is zero (if it is zero, go to step S134, otherwise go to step S135. In other words, if it is not attenuated at all, the attenuation is set to step S134. If yes, go to step S135.
[S134] A lower limit alarm for VATT 14 is generated (because the light level cannot be increased any more).
[S135] It is determined whether a lower limit alarm is occurring. If it is occurring, go to step S136, otherwise go to step S137.
[S136] The lower limit alarm of VATT14 is recovered.
[S137] Decrease the attenuation of the VATT 14 (increase the light level).
[S138] The monitor value is acquired from the PD 17f. Then, the process returns to step S116, and the estimated level of the Thru light is calculated again.
[S139] An expected attenuation value (Pexthru dec) is calculated. Pexthru dec = Pguthru−Pmax thru.
[S140] It is determined whether the attenuation of the VATT 14 is maximum. If so, go to step S141, otherwise go to step S142.
[S141] An upper limit alarm of VATT14 is generated (because the light level cannot be lowered any more).
[S142] It is determined whether an upper limit alarm is occurring. If it is occurring, go to step S43, otherwise go to step S144.
[S143] The upper limit alarm of VATT14 is recovered.
[S144] The attenuation of VATT 14 is increased (the light level is lowered). Then, the process goes to step S138.
[0080]
As described above, according to the present invention, attenuation by VATT and monitoring by PD are not performed for all wavelengths after complete wavelength separation, but attenuation and monitoring are performed in a lump while being multiplexed. . Thereby, it is possible to reduce the cost for preparing VATT / PD in all relay stations of the system.
[0081]
Further, by integrating the device that receives the optical signal from the previous station and the device that transmits the optical signal to the next station, the device configuration can be simplified. As a result, the number of fiber connections is reduced, reducing the work burden on the maintenance personnel. In addition, human error is reduced and reliability is improved. Furthermore, since the light level adjustment by VATT can be performed automatically, it becomes possible to improve operational efficiency and convenience.
[0082]
(Supplementary note 1) In an optical transmission apparatus that performs WDM optical transmission,
A preamplifier for receiving and amplifying the optical signal from the previous station;
A post-amplifier that amplifies the combined optical signal and transmits it to the next station;
An optical branching unit for branching the optical signal amplified by the preamplifier into Thru light and Drop light;
A first optical variable attenuator that collectively adjusts the optical level of wavelength-multiplexed Thru light based on the control signal;
A second optical variable attenuator for collectively adjusting the optical level of the Add light after wavelength multiplexing based on the control signal;
An optical multiplexing unit for multiplexing the optical signals output from the first optical variable attenuator and the second optical variable attenuator;
An optical monitor that monitors optical signals output from the first optical variable attenuator and the second optical variable attenuator;
Based on the monitor result, the control signal is generated within the input level range of the post-amplifier and the optical level of each wavelength is the same value, and the first optical variable attenuator and the first optical attenuator An optical level adjustment control unit that performs adjustment control of the optical level of the optical variable attenuator 2;
An optical transmission device comprising:
[0083]
(Supplementary Note 2) The optical monitor unit includes a first monitor unit that monitors an output of the first optical variable attenuator, a second monitor unit that monitors an output of the second optical variable attenuator, The optical transmission device as set forth in appendix 1, wherein
[0084]
(Additional remark 3) The said light level adjustment control part is based on the upper-limit value and lower-limit value of the optical level prescribed | regulated by the said post-amplifier, and the optical level upper limit of Thru light from each wavelength number ratio of Thru light and Add light. Value and lower limit value, and the light level upper limit value and lower limit value of the Add light, and the monitor value by the first monitor unit is within the range of the calculated upper limit value and lower limit value of the Thru light, The optical transmission device according to appendix 2, wherein the optical level adjustment control is performed so that the monitor value by the second monitor unit is within the range of the calculated upper limit value and lower limit value of the Add light.
[0085]
(Additional remark 4) The said optical monitor part monitors the output of the said optical multiplexing part, The optical transmission apparatus of Additional remark 1 characterized by the above-mentioned.
(Supplementary Note 5) The light level adjustment control unit sets the attenuation control width of either the first optical variable attenuator or the second optical variable attenuator to a fixed value, and sets the other attenuation control width to Thru light. Attenuation control widths of both of the light levels so that the monitor value of the light monitor unit falls within the upper limit value and the lower limit value of the light level defined by the postamplifier. The optical transmission device according to appendix 4, wherein the optical level adjustment control is performed by moving
[0086]
(Supplementary Note 6) The light level adjustment control unit is configured to input the signal to the post amplifier in spite of setting the attenuation of the first optical variable attenuator or the second optical variable attenuator to the maximum attenuation. If the light level exceeds the upper limit value, or if the input light to the post amplifier falls below the lower limit value even though the minimum attenuation is set, an alarm is issued, and after the alarm is issued, The optical transmission device according to appendix 1, wherein an alarm recovery is notified when the input optical level falls within the upper limit value and the lower limit value.
[0087]
(Supplementary Note 7) In an optical transmission apparatus that performs WDM optical transmission,
A preamplifier for receiving and amplifying the optical signal from the previous station;
A post-amplifier that amplifies the combined optical signal and transmits it to the next station;
An optical branching unit for branching the optical signal amplified by the preamplifier into Thru light and Drop light;
A first optical variable attenuator that collectively adjusts the optical level of wavelength-multiplexed Thru light based on the control signal;
A second optical variable attenuator for individually adjusting the optical level of each Add light before wavelength multiplexing based on the control signal;
An optical multiplexing unit that multiplexes the optical signal output from the first optical variable attenuator and the optical signal output from the second optical variable attenuator and wavelength-multiplexed;
An optical monitor unit for monitoring an optical signal output from the first optical variable attenuator and the second optical variable attenuator;
Based on the monitoring result, the control signal is generated within the input level range of the post-amplifier and the optical levels of the respective wavelengths all have the same value, and the first optical variable attenuator and the second optical attenuator An optical level adjustment control unit that performs adjustment control of the optical level of the optical variable attenuator of
An optical transmission device comprising:
[0088]
(Supplementary Note 8) The optical monitor unit includes a first monitor unit that monitors an output of the first optical variable attenuator, a second monitor unit that monitors an output of the second optical variable attenuator, The optical transmission device according to appendix 7, characterized in that:
[0089]
(Supplementary Note 9) The light level adjustment control unit, based on the upper limit value and the lower limit value of the light level defined by the post-amplifier, determines the upper limit of the light level of the Thru light from the ratio of the wavelength numbers of the Thru light and the Add light. Value and lower limit value, and the light level upper limit value and lower limit value of Add light, and the monitor value by the first monitor unit falls within the calculated upper limit value and lower limit value range of Thru light, 9. The optical transmission apparatus according to appendix 8, wherein the optical level adjustment control is performed so that the monitor value by the second monitor unit falls within the range of the calculated upper limit value and lower limit value of the Add light.
[0090]
(Additional remark 10) The said optical monitor part monitors the output of the said optical multiplexing part, The optical transmission apparatus of Additional remark 7 characterized by the above-mentioned.
(Additional remark 11) The said light level adjustment control part is based on the upper-limit value and lower-limit value of the optical level prescribed | regulated by the said post-amplifier, and the optical level upper limit of Thru light from each wavelength number ratio of Thru light and Add light. Value and lower limit value, and upper and lower limit values of the light level of Add light are calculated, and the light level estimated value of Thru light and the light level estimated value of Add light are obtained based on the monitor value of the light monitor unit. The light level estimation value of the Thru light is within the range of the calculated upper limit value and lower limit value of the Thru light, and the light level estimation value of the Add light is within the range of the calculated upper limit value and lower limit value of the Add light. The optical transmission device according to appendix 10, wherein the optical level adjustment control is performed so that the optical level is within the range.
[0091]
(Supplementary Note 12) The light level adjustment control unit is configured to input the signal to the postamplifier even though the attenuation of the first optical variable attenuator or the second optical variable attenuator is set to the maximum attenuation. If the light level exceeds the upper limit value, or if the input light to the post amplifier falls below the lower limit value even though the minimum attenuation is set, an alarm is issued, and after the alarm is issued, The optical transmission device according to appendix 7, wherein an alarm recovery is notified when the input optical level falls within the upper limit value and the lower limit value.
[0092]
(Additional remark 13) In the optical level adjustment method which adjusts the optical level of the optical signal at the time of WDM transmission,
The optical signal after receiving and amplifying the optical signal from the previous station is branched into Thru light and Drop light,
Based on the control signal, the optical level of the Thru light that is wavelength-multiplexed is collectively adjusted by the first optical variable attenuator,
Based on the control signal, the optical level of the Add light after wavelength multiplexing is collectively adjusted by the second optical variable attenuator,
Combining optical signals output from the first optical variable attenuator and the second optical variable attenuator;
Monitoring the optical signal after being output from the first optical variable attenuator and the second optical variable attenuator;
For the post-amplifier for amplifying the combined optical signal and transmitting it to the next station, the monitoring result is set so that the optical level of each wavelength is the same value within the input level range of the post-amplifier. An optical level adjustment method comprising: generating the control signal based on the control signal and performing adjustment control of optical levels of the first optical variable attenuator and the second optical variable attenuator.
[0093]
(Supplementary Note 14) Based on the upper and lower limits of the light level defined by the post-amplifier, the upper and lower limits of the light level of the Thru light and the Add light from the wavelength number ratio of the Thru light and the Add light. And the monitor value obtained by monitoring the output of the first optical variable attenuator is within the range of the calculated upper and lower limits of the Thru light, and The light level adjustment control is performed so that the monitor value obtained by monitoring the output of the second optical variable attenuator falls within the range of the calculated upper limit value and lower limit value of the Add light. Light level adjustment method.
[0094]
(Supplementary Note 15) The attenuation control width of either the first optical variable attenuator or the second optical variable attenuator is a fixed value, and the other attenuation control width is the ratio of the number of wavelengths of the Thru light and the Add light. By moving both attenuation control widths so that the monitor value obtained by monitoring from the combined output signal is within the range between the upper limit value and the lower limit value of the light level defined by the post-amplifier, 14. The light level adjustment method according to appendix 13, wherein the light level adjustment control is performed.
[0095]
(Supplementary Note 16) The input light level to the post-amplifier exceeds the upper limit value even though the attenuation of the first optical variable attenuator or the second optical variable attenuator is set to the maximum attenuation. If the input light to the post-amplifier falls below the lower limit even though the minimum attenuation is set, an alarm is issued, and after the alarm is issued, the input light level to the post-amplifier is set to the upper and lower limits. 14. The light level adjustment method according to appendix 13, wherein alarm recovery is notified when the value falls within the value.
[0096]
(Supplementary Note 17) In an optical level adjustment method for adjusting the optical level of an optical signal during WDM transmission,
The optical signal after receiving and amplifying the optical signal from the previous station is branched into Thru light and Drop light,
Based on the control signal, the optical level of the Thru light that is wavelength-multiplexed is collectively adjusted by the first optical variable attenuator,
Based on the control signal, the optical level of each Add light before wavelength multiplexing is individually adjusted by the second optical variable attenuator,
Combining the optical signal output from the first optical variable attenuator and the optical signal output from the second optical variable attenuator and wavelength-multiplexed;
Monitoring the optical signal after being output from the first optical variable attenuator and the second optical variable attenuator;
For the post-amplifier for amplifying the combined optical signal and transmitting it to the next station, the monitoring result is set so that the optical level of each wavelength is the same value within the input level range of the post-amplifier. An optical level adjustment method comprising: generating the control signal based on the control signal and performing adjustment control of optical levels of the first optical variable attenuator and the second optical variable attenuator.
[0097]
(Supplementary Note 18) Based on the upper and lower limits of the light level specified by the post-amplifier, the upper and lower limits of the light level of the Thru light and the Add light from the wavelength number ratio of the Thru light and the Add light. And the monitor value obtained by monitoring the output of the first optical variable attenuator is within the range of the calculated upper and lower limits of the Thru light, and The light level adjustment control is performed so that the monitor value obtained by monitoring the output of the second optical variable attenuator falls within the calculated upper limit value and lower limit value of the Add light. Light level adjustment method.
[0098]
(Supplementary Note 19) Based on the upper and lower limits of the light level defined by the post-amplifier, the upper and lower limits of the optical level of the Thru light and the Add light from the wavelength number ratio of the Thru light and the Add light. The light level upper limit value and the lower limit value are calculated, and based on the monitor value obtained by monitoring the combined output signal, the Thru light level estimation value and the Add light level estimation value are obtained, and the Thru light level is calculated. The estimated light level is within the range of the calculated upper and lower limits of the Thru light, and the estimated light level of the Add light is within the range of the calculated upper and lower limits of the Add light. 18. The light level adjustment method according to appendix 17, wherein the light level adjustment control is performed.
[0099]
(Supplementary Note 20) When the input light level to the post amplifier exceeds the upper limit value even though the attenuation of the first optical variable attenuator or the second optical variable attenuator is set to the maximum attenuation If the input light to the post-amplifier falls below the lower limit even though the minimum attenuation is set, an alarm is issued, and after the alarm is issued, the input light level to the post-amplifier is set to the upper and lower limits. 18. The light level adjustment method according to appendix 17, wherein alarm recovery is notified when the value falls within the value.
[0100]
【The invention's effect】
  As explained above,lightThe transmission apparatus generates a control signal based on the monitor result so that the optical levels of the respective wavelengths are all the same value within the input level range of the post-amplifier, and collectively collects the optical levels of all the Thru lights. The optical level adjustment control of the first optical variable attenuator to be adjusted and the second optical variable attenuator that collectively adjusts the optical levels of all the Add lights after wavelength multiplexing is performed. As a result, high-quality optical level adjustment control can be performed, so that the apparatus scale can be reduced and the quality and reliability of optical transmission can be improved.
  Further, the attenuation control width of one of the first optical variable attenuator for adjusting the optical level of the Thru light and the second optical variable attenuator for adjusting the optical level of the Add light is set to a fixed value, and the other attenuation control is performed. The width is determined from the ratio of the number of wavelengths of the Thru light and the Add light, and the monitor value of the optical monitor unit arranged at the subsequent stage of the combined portion of the Thru light and the Add light is the upper limit of the light level defined by the postamplifier. The light level adjustment control is performed by controlling both attenuation control widths so as to be within the range of the value and the lower limit value. As a result, high-quality optical level adjustment control can be performed, so that the apparatus scale can be reduced and the quality and reliability of optical transmission can be improved.
[Brief description of the drawings]
[Figure 1]lightIt is a principle diagram of a transmission apparatus.
FIG. 2 is a diagram illustrating a configuration of a first embodiment of an optical transmission apparatus.
FIG. 3 is a flowchart of light level adjustment control according to the first embodiment.
FIG. 4 is a flowchart illustrating light level adjustment control according to the first embodiment.
FIG. 5 is a flowchart of light level adjustment control according to the first embodiment.
FIG. 6 is a flowchart illustrating light level adjustment control according to the first embodiment.
FIG. 7 is a flowchart illustrating light level adjustment control according to the first embodiment.
FIG. 8 is a diagram illustrating a configuration of a second embodiment of an optical transmission apparatus;
FIG. 9 is a flowchart illustrating light level adjustment control according to the second embodiment.
FIG. 10 is a diagram illustrating a flowchart of light level adjustment control according to the second embodiment.
FIG. 11 is a flowchart of light level adjustment control according to the second embodiment.
FIG.lightIt is a principle diagram of a transmission apparatus.
FIG. 13 is a diagram illustrating a configuration of a first embodiment of an optical transmission device;
FIG. 14 is a flowchart of light level adjustment control according to the first embodiment.
FIG. 15 is a diagram illustrating a flowchart of light level adjustment control according to the first embodiment;
FIG. 16 is a flowchart illustrating light level adjustment control according to the first embodiment;
FIG. 17 is a diagram illustrating a configuration of a second embodiment of an optical transmission apparatus;
FIG. 18 is a flowchart illustrating light level adjustment control according to the second embodiment.
FIG. 19 is a flowchart of light level adjustment control according to the second embodiment.
FIG. 20 is a flowchart illustrating light level adjustment control according to the second embodiment.
FIG. 21 is a diagram illustrating a configuration of a conventional WDM apparatus.
[Explanation of symbols]
10 Optical transmission equipment
11 Preamplifier
12 Post amplifier
13 Optical branch
13a Optical coupler
13b DMUX
14 First optical variable attenuator
15 Second optical variable attenuator
16 Optical multiplexing part
17 Optical monitor
18 Light level adjustment controller
19 MUX

Claims (2)

In an optical transmission apparatus that performs WDM optical transmission,
A preamplifier for receiving and amplifying the optical signal from the previous station;
A post-amplifier that amplifies the combined optical signal and transmits it to the next station;
An optical branching unit for branching the optical signal amplified by the preamplifier into Thru light and Drop light;
A first optical variable attenuator that collectively adjusts the optical level of wavelength-multiplexed Thru light based on the control signal;
A second optical variable attenuator that collectively adjusts the optical level of the Add light after wavelength multiplexing based on the control signal;
An optical multiplexing unit for multiplexing the optical signals output from the first optical variable attenuator and the second optical variable attenuator;
An optical monitor unit for monitoring optical signals output from the first optical variable attenuator and the second optical variable attenuator;
Based on the monitor result, the control signal is generated within the input level range of the post-amplifier so that the optical levels of the respective wavelengths all have the same value, and the first optical variable attenuator and the first optical attenuator An optical level adjustment control unit that performs adjustment control of the optical level of the optical variable attenuator 2;
With
The optical monitor unit includes a first monitor unit that monitors the output of the first optical variable attenuator, and a second monitor unit that monitors the output of the second optical variable attenuator,
The light level adjustment control unit, based on the upper limit value and the lower limit value of the light level defined by the post-amplifier, from the ratio of the number of wavelengths of the Thru light and the Add light, the upper limit value and the lower limit value of the Thru light And the light level upper limit value and the lower limit value of the Add light, the monitor value by the first monitor unit is within the range of the calculated upper limit value and lower limit value of the Thru light, and the second The light level adjustment control is performed so that the monitor value of the monitor unit falls within the range of the calculated upper limit value and lower limit value of the Add light.
An optical transmission device characterized by that. In an optical transmission apparatus that performs WDM optical transmission,
  A preamplifier for receiving and amplifying the optical signal from the previous station;
  A post-amplifier that amplifies the combined optical signal and transmits it to the next station;
  An optical branching unit for branching the optical signal amplified by the preamplifier into Thru light and Drop light;
  A first optical variable attenuator that collectively adjusts the optical level of wavelength-multiplexed Thru light based on the control signal;
  A second optical variable attenuator that collectively adjusts the optical level of the Add light after wavelength multiplexing based on the control signal;
  An optical multiplexing unit for multiplexing the optical signals output from the first optical variable attenuator and the second optical variable attenuator;
  An optical monitor that monitors optical signals output from the first optical variable attenuator and the second optical variable attenuator;
  Based on the monitor result, the control signal is generated within the input level range of the post-amplifier and the optical level of each wavelength is the same value, and the first optical variable attenuator and the first optical attenuator An optical level adjustment control unit that performs adjustment control of the optical level of the optical variable attenuator 2;
  With
  The optical monitor unit monitors the output of the optical multiplexing unit,
  The light level adjustment control unit sets the attenuation control width of either the first optical variable attenuator or the second optical variable attenuator to a fixed value, and sets the other attenuation control width to Thru light and Add light, respectively. Both are controlled by an attenuation control width so that the monitor value of the optical monitor unit falls within the range of the upper limit value and the lower limit value of the light level specified by the postamplifier. , Perform light level adjustment control,
  An optical transmission device characterized by that.

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