JP3857066B2

JP3857066B2 - Gain control apparatus and gain control method

Info

Publication number: JP3857066B2
Application number: JP2001111637A
Authority: JP
Inventors: 浩行圷
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2001-04-10
Filing date: 2001-04-10
Publication date: 2006-12-13
Anticipated expiration: 2021-04-10
Also published as: JP2002314357A

Description

【０００１】
【発明の属する技術分野】
本発明は、受信装置のＡＧＣ（ＡｕｔｏｍａｔｉｃＧａｉｎＣｏｎｔｒｏｌ）回路とそれを用いた受信装置に関する。
【０００２】
【従来の技術】
図５は、従来の受信装置に用いられる切替式ＡＧＣ回路の一例を示す。
１は受信アンテナ、５は増幅回路（固定増幅回路）、６は減衰回路（固定減衰回路）、４ａ，４ｂは増幅回路５と減衰回路６の切替を行うスイッチ、８はスイッチ切替を行う制御部、７は受信信号の復調部である。
【０００３】
次に、動作について説明する。
上記の切替式ＡＧＣ回路が図６に示すヒステリシス特性で増幅回路５と減衰回路６とを切り替える場合を説明する。
受信アンテナ１によって受信された受信信号からＲＳＳＩ（ＲｅｃｅｉｖｅｄＳｉｇｎａｌＳｔｒｅｎｇｔｈＩｎｄｉｃａｔｏｒ）信号が制御部８へ入ると、そのレベルがＬ２以下の場合、受信信号は増幅回路５を通過するように制御部８によってスイッチの選択が行われる。ＲＳＳＩレベルが増加しＬ２を超えると、受信信号は減衰回路６を通過するように制御部８によってスイッチの選択が行われる。逆に、ＲＳＳＩレベルが減少する場合、Ｌ２では切替動作は行われず、Ｌ１まで減少してから、受信信号が増幅回路５を通過するように制御部８によってスイッチの選択が行われる。Ｌ１とＬ２のレベルの幅は、通常、ＲＳＳＩレベルの瞬時変動幅より大きく設定され、このＲＳＳＩの瞬時変動幅がＡＧＣ切替に影響を及ぼさないようにある固定の値に設定されている。
【０００４】
また、ＡＧＣ切替を行わない場合の増幅器側の受信のダイナミックレンジはＬ２−Ｌｍｉｎ、減衰器側の受信のダイナミックレンジはＬｍａｘ−Ｌ１であり、通常、Ｌ２−Ｌｍｉｎ＝Ｌｍａｘ−Ｌ１である。
【０００５】
【発明が解決しようとする課題】
従来の切替式ＡＧＣ回路のヒステリシス幅Ｌ２−Ｌ１は、固定で、ＲＳＳＩの瞬時変動の最悪値に合わせて設定されているため、ＲＳＳＩの瞬時変動幅が小さいとき、ダイナミックレンジ（受信信号レベルの高さの範囲）の面で非効率的であった。
また、回路の切替時の受信信号レベルの不連続性によってビットエラーが発生するのを防ぐために、ＡＧＣ切替ヒステリシス幅をＲＳＳＩ瞬時変動幅の最悪値よりも大きくする必要があった。
【０００６】
この発明は、ＲＳＳＩの瞬時変動幅に応じてＡＧＣ回路の切替を行うことで、ＲＳＳＩ瞬時変動幅の小さいときの受信ダイナミックレンジを拡大することができるＡＧＣ制御装置及びＡＧＣ制御方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
この発明に係る利得制御装置は、異なる複数の減衰量のうちいずれかの減衰量を用いて受信した信号を減衰する減衰回路部と、
受信した信号の受信信号レベルを検出し、検出した受信信号レベルを用いて、受信信号レベルの変動量を算出し、上記変動量に基づいて上記複数の減衰量から一の減衰量を選択し、選択した一の減衰量に基づいて上記減衰回路部を動作させて、受信信号レベルを制御する制御部とを備えることを特徴とする。
【０００８】
上記減衰回路部は、少なくとも第一の減衰量と、上記第一の減衰量よりも大きい第二の減衰量とのいずれかを用いて受信した信号を減衰し、
上記制御部は、上記変動量が所定の変動基準値より大きい場合は、上記第一の減衰量を選択し、上記変動量が上記所定の変動基準値より小さい場合は、上記第二の減衰量を選択することを特徴とする。
【０００９】
上記制御部は、所定の期間内に受信した信号の複数の受信信号レベルを平均して平均レベルを算出し、平均レベルと上記変動量とを用いて、受信信号レベルを制御することを特徴とする。
【００１０】
上記利得制御装置は、さらに、受信した信号を増幅する増幅回路を備え、
上記減衰回路部は、少なくとも第一の減衰量と、上記第一の減衰量よりも大きい第二の減衰量とのいずれかを用いて受信した信号を減衰し、
上記制御部は、上記平均レベルが所定の平均基準値より小さい場合は、上記増幅回路を選択し、上記平均レベルが所定の平均基準値より大きくかつ上記変動量が所定の変動基準値より大きい場合は、第一の減衰量を選択し、上記平均レベルが所定の平均基準値より大きくかつ上記変動量が所定の変動基準値より小さい場合は、第二の減衰量を選択することをを特徴とする。
【００１１】
上記減衰回路部は、減衰量の異なる複数の回路を備え、
上記制御部は、上記変動幅に基づいて、上記複数の回路から一の回路を選択し、選択した回路を用いて受信レベルを制御することを特徴とする。
【００１２】
上記減衰回路部は、減衰量を調整する減衰量調整部と、
上記減衰量調整部が調整した減衰量を用いて受信した信号を減衰する回路とを備え、
上記制御部は、選択した減衰量を上記減衰量調整部へ出力し、
上記減衰量調整部は、上記制御部から入力した減衰量に基づいて減衰量を調整することを特徴とする。
【００１３】
上記減衰量調整部は、減衰量を段階的に調整することを特徴とする。
【００１４】
上記制御部は、上記変動量に基づいて、複数の減衰量から一の減衰量を選択することによって、受信する信号の受信信号レベルの高さの範囲を拡大することを特徴とする。
【００１５】
この発明に係る利得制御方法は、異なる複数の減衰量のいずれかを用いて受信した信号を減衰する減衰回路部を備える利得制御方法において、
受信した信号の受信信号レベルを検出し、
検出した受信信号レベルを用いて、受信信号レベルの変動量を算出し、
算出した変動量に基づいて上記複数の減衰量から一の減衰量を選択し、
選択した一の減衰量と上記減衰回路部とを用いて、受信信号レベルを制御することを特徴とする。
【００１６】
【発明の実施の形態】
実施の形態１．
この実施の形態では、受信信号を増幅する増幅回路と、受信信号を減衰する複数の減衰回路（複数の減衰回路を減衰回路部という）と、受信信号レベル（ＲＳＳＩ）を検出し、増幅回路と減衰回路との切替を行う制御部とを備えるＡＧＣ制御装置（利得制御装置）について説明する。
制御部は、（１）ＲＳＳＩ平均レベルが小さいときは、受信信号が増幅回路を通過するようにスイッチの切替を行い、（２）ＲＳＳＩ平均レベルが所定の平均基準値より大きく、かつ、ＲＳＳＩ瞬時変動幅が所定の平均変動値より大きいときは、受信信号が従来の減衰回路を通過するようにスイッチの切替を行い、（３）ＲＳＳＩ平均レベルが所定の平均基準値より大きく、かつ、ＲＳＳＩ瞬時変動幅が所定の変動値より小さいときは、受信信号が減衰量のより大きい減衰回路を通過するようにスイッチの切替を行う。ＲＳＳＩ平均レベルの高い信号も受信できるようにすることで、より広いダイナミックレンジを得ることができるようにする。
以下に、図を用いて説明する。
【００１７】
図１は、本発明の実施の形態１におけるＡＧＣ制御装置の回路構成を示している。図５の従来例と同様な構成要素には、同じ符号を付してある。
図１において、１は受信アンテナ、２ａと２ｂは受信回路、３は受信帯域制限フィルタである。受信帯域制限フィルタ３を通過した受信信号のうち、一方はスイッチ４ａへ入り、他方は制御部８へ入る。制御部８は、ＲＳＳＩ検出とＡＧＣ回路切替を行う。スイッチ４ａとスイッチ４ｂは、ＡＧＣ回路の切替を行うスイッチでありる。スイッチ４ａとスイッチ４ｂの間には、ＡＧＣ回路として、増幅回路５とｎ種類の異なる減衰量の減衰回路６ａ，６ｂ，．．．，６ｎがある。これらの回路を通過し、最終的に受信信号は、７の復調部へ入る構成となっている。図１の例では、減衰回路６ａと減衰回路６ｂを備える場合（ｎ＝２の場合）を示している。
【００１８】
制御部８は、受信した信号から受信信号レベル（ＲＳＳＩ）を検出する。また、制御部８は、検出した受信信号レベルに基づいて、ＲＳＳＩ平均レベル（受信信号レベルの平均レベル）と、ＲＳＳＩ瞬時変動幅（変動量）とを算出する。
ＲＳＳＩ平均レベルは、所定の期間内に受信された複数の信号の受信信号レベルの平均値である。
ＲＳＳＩ瞬時変動幅は、少なくとも二つの受信信号レベルの差である。変動幅を算出する受信信号レベルは、任意の複数の受信信号レベルから算出するものであり、任意の複数の受信信号レベルは、所定の期間に受信された信号の受信信号レベルであってもよい。
【００１９】
図２は、本発明の実施の形態１におけるＡＧＣ制御装置の回路切替ヒステリシス特性を示すものである。
増幅回路５のダイナミックレンジはＬ２−Ｌ０、減衰回路６ａのダイナミックレンジはＬ３−Ｌ１、減衰回路６ｂのダイナミックレンジはＬ５−Ｌ４である。また、増幅回路５と減衰回路６ａを使用したときのＡＧＣ切替ヒステリシス幅はＬ２−Ｌ１、増幅回路５と減衰回路６ｂを使用したときのＡＧＣ切替ヒステリシス幅はＬ２−Ｌ４である。
【００２０】
受信アンテナ１で捉えられた受信信号は、受信回路２ａを通過し、受信帯域制限フィルタ３を通過する。そして、一つはＡＧＣ回路切替スイッチ４ａへ、一つはＲＳＳＩレベル検出部を備えた制御部８へ入る。
【００２１】
検出されたＲＳＳＩ平均レベルまたはＲＳＳＩ瞬時変動幅がＬ０〜Ｌ１の範囲内にあるとき、制御部８は、ＡＧＣ回路として増幅回路５を選択するようにスイッチ４ａ，４ｂを制御する。
【００２２】
検出されたＲＳＳＩ平均レベルまたはＲＳＳＩ瞬時変動幅がＬ１〜Ｌ４の範囲内にあるとき、制御部８は、増幅回路５あるいは減衰回路６ａのいずれかを選択する。実際の動作としては、現状のＡＧＣ回路（現在選択されている回路）を維持するように動作する。
【００２３】
検出されたＲＳＳＩ平均レベルまたはＲＳＳＩ瞬時変動幅がＬ４〜Ｌ２の範囲内にあるとき、制御部８は、増幅回路５あるいは減衰回路６ｂのいずれかを選択する。実際の動作としては、現状のＡＧＣ回路を維持するように動作する。
【００２４】
検出されたＲＳＳＩ平均レベルまたはＲＳＳＩ瞬時変動幅がＬ２〜Ｌ３の範囲内にあり、ＲＳＳＩ瞬時変動幅がＬ２−Ｌ４より大きい場合には、制御部８は、減衰回路６ａを選択するようにＡＧＣ切替動作する。
【００２５】
検出されたＲＳＳＩ平均レベルまたはＲＳＳＩ瞬時変動幅がＬ２〜Ｌ３の範囲内にあり、ＲＳＳＩ瞬時変動幅がＬ２−Ｌ４より小さい場合には、制御部８は、減衰回路６ｂを選択するようにＡＧＣ切替動作する。
【００２６】
このように、本実施の形態１によれば、ＲＳＳＩ瞬時変動がＬ２−Ｌ４より大きい場合には、従来通りの受信ダイナミックレンジＬ３−Ｌ０を確保するが、ＲＳＳＩ瞬時変動がＬ２−Ｌ４より小さい場合には受信ダイナミックレンジがＬ５−Ｌ０と広げることができるようになる。
このように、この発明に係るＡＧＣ制御装置は、ＲＳＳＩの瞬時変動幅を検出して、ＲＳＳＩ絶対レベルが大きく、かつ、その変動幅が大きいときは、従来の切替ヒステリシス特性をもつ減衰回路を使用し、ＲＳＳＩ絶対レベルが大きく、かつ、その変動幅が小さいときは、受信レベルの高い信号の入力受信を可能にする減衰回路を使用し、受信のダイナミックレンジを広くすることができるようにしたものである。
【００２７】
以上のように、この実施の形態のＡＧＣ制御装置（利得制御装置）は、低い受信入力電圧を増幅する増幅回路と、高い受信入力電圧を減衰する複数の減衰回路（減衰回路部）と、受信信号レベルに応じて利得切替を行う制御部を備え、制御部は、受信信号レベルの変動幅を監視し、変動幅が大きいときは減衰量の小さい回路を使用してヒステリシスの大きい切り替え特性を持たせ電界変動によるビットエラーの発生を抑え、変動幅が小さいときは減衰量の大きい回路を使用してヒステリシスの小さい切り替え特性を持たせ受信入力電圧のダイナミックレンジを広くすることを特徴とする。
【００２８】
実施の形態２．
この実施の形態では、受信信号を増幅する増幅回路と、受信信号を減衰する１つの可変減衰回路（減衰回路部）と、受信信号レベル（ＲＳＳＩ）を検出し、増幅回路と減衰回路との切替を行う制御部とを備えるＡＧＣ制御装置（利得制御装置）について説明する。
減衰量を大きく制御し、ＲＳＳＩ平均レベルの高い信号も受信できるようにすることで、より広いダイナミックレンジを得ることができるようにする。
【００２９】
図３は、本発明の実施の形態２を示している。
実施の形態１で、減衰回路６ａ，６ｂ，．．．，６ｎは、減衰量の異なるｎ種類の回路を備えていたが、それらの代わりに、一つの可変減衰回路６となっている。この可変減衰回路は、減衰量を外部からの制御によって段階的または連続的に変化させることができるものである。
【００３０】
図３には明記していないが、可変減衰回路６は、減衰量を調整する減衰量調整部と、減衰量調整部が調整した減衰量を用いて受信した信号を減衰する回路とを備える。
制御部８は、選択した減衰量を減衰量調整部へ出力し、減衰量調整部は、上記制御部から入力した減衰量に基づいて減衰量を調整する。
制御部８は、予め決められた複数の減衰量から一つの減衰量を選択してもよいし、ＲＳＳＩ瞬時変動幅に基づいて、減衰量を算出してもよいし、その他の方法で減衰量を決定してもよい。制御部８は、いずれかの方法で決定した減衰量を選択した減衰量として減衰調整部へ出力する。
【００３１】
図４は、本発明の実施の形態２におけるＡＧＣ制御装置の回路切替ヒステリシス特性を示すものである。
増幅回路５のダイナミックレンジはＬ２−Ｌ０、可変減衰回路６のダイナミックレンジの一例ａはＬ３−Ｌ１、可変減衰回路のダイナミックレンジの一例ｂはＬ５−Ｌ４である。また、増幅回路５と可変減衰回路６の例ａを使用したときのＡＧＣ切替ヒステリシス幅はＬ２−Ｌ１、増幅回路５と可変減衰回路６の例ｂを使用したときのＡＧＣ切替ヒステリシス幅はＬ２−Ｌ４である。
【００３２】
本実施の形態２では、実施の形態１の場合の減衰回路を切り替えてＡＧＣ制御を行う代わりに、減衰回路の減衰量を段階的または連続的に外部制御することで実施の形態１と同様の効果を得るものである。
【００３３】
以上のように、この実施の形態のＡＧＣ制御装置（利得制御装置）は、低い受信入力電圧を増幅する増幅回路と、高い受信入力電圧を減衰し減衰量を変化できる減衰回路（減衰回路部）と、受信信号レベルに応じて利得切替を行う制御部を備え、制御部は、受信信号レベルの変動幅を監視し、変動幅が大きいときは減衰量の小さい回路を使用してヒステリシスの大きい切り替え特性を持たせ電界変動によるビットエラーの発生を抑え、変動幅が小さいときは減衰量の大きい回路を使用して変動幅に応じて減衰量を段階的または連続的に変化させ最適なヒステリシス切り替え特性を持たせ受信入力電圧のダイナミックレンジを広くすることを特徴とする。
【００３４】
実施の形態３．
上記実施の形態では、異なる複数の減衰量を用いて受信した信号を減衰する減衰回路部として、異なる減衰量を有する複数の減衰回路を用いる場合と、可変減衰回路を用いる場合とを説明した。しかしながら、減衰回路部は、上記の場合に限られることなく、その他の構成であってもかまわない。
制御部８が、受信信号レベルの変動量に基づいて、複数の減衰量から一の減衰量を選択し、選択した一の減衰量を用いて、受信信号レベルを制御する装置及び方法であれば、この他のものであってもかまわない。また、制御部８が変動量に基づいて、減衰量を算出し、算出した減衰量を用いて、信号を減衰することを制御する装置及び方法であってもよい。
【００３５】
【発明の効果】
以上のように、この発明によれば、ＲＳＳＩの平均レベルのみによるＡＧＣ制御だけでなく、ＲＳＳＩ変動幅が大きいときは減衰量の小さい回路を選択し、ＲＳＳＩ変動幅の小さい時は減衰量の大きい回路を選択するというようにＡＧＣ回路の切替を最適化することで、受信ダイナミックレンジを広くすることができる。
【００３６】
異なる減衰量を有する複数の減衰回路を用いて、受信ダイナミックレンジを拡大することができる。
【００３７】
減衰量を調整できる可変減衰回路を用いることによって、受信ダイナミックレンジを拡大することができる。
【００３８】
また、可変減衰回路によって、減衰量を段階的に、あるいは，連続的に切り替えることができる。
【図面の簡単な説明】
【図１】本発明の実施の形態１におけるＡＧＣ制御装置の回路の構成を示すブロック図。
【図２】本発明の実施の形態１におけるＡＧＣ制御装置の回路切替ヒステリシス特性を示す図。
【図３】本発明の実施の形態２におけるＡＧＣ制御装置の回路の構成を示すブロック図。
【図４】本発明の実施の形態２におけるＡＧＣ制御装置の回路切替ヒステリシス特性を示す図。
【図５】従来例におけるＡＧＣ制御装置の回路の構成を示すブロック図。
【図６】従来例におけるＡＧＣ制御装置の回路切替ヒステリシス特性を示す図。
【符号の説明】
１受信アンテナ、２ａ〜２ｂ受信回路、３受信帯域制限フィルタ、４ａ，４ｂＡＧＣ回路切替スイッチ（スイッチ）、５増幅回路、６可変減衰回路、６ａ，６ｂ減衰回路、７復調部、８制御部（ＲＳＳＩ検出部を含む制御部）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an AGC (Automatic Gain Control) circuit of a receiving apparatus and a receiving apparatus using the same.
[0002]
[Prior art]
FIG. 5 shows an example of a switchable AGC circuit used in a conventional receiving apparatus.
1 is a receiving antenna, 5 is an amplifying circuit (fixed amplifying circuit), 6 is an attenuating circuit (fixed attenuating circuit), 4a and 4b are switches for switching between the amplifying circuit 5 and the attenuating circuit 6, and 8 is a control unit for switching the switch. , 7 are demodulation units for the received signal.
[0003]
Next, the operation will be described.
A case will be described in which the switchable AGC circuit switches between the amplifier circuit 5 and the attenuation circuit 6 with the hysteresis characteristic shown in FIG.
When an RSSI (Received Signal Strength Indicator) signal enters the control unit 8 from the received signal received by the receiving antenna 1, the control unit 8 switches the switch so that the received signal passes through the amplifier circuit 5 when the level is L2 or less. A selection is made. When the RSSI level increases and exceeds L2, the switch is selected by the control unit 8 so that the received signal passes through the attenuation circuit 6. On the contrary, when the RSSI level decreases, the switching operation is not performed in L2, and the switch is selected by the control unit 8 so that the received signal passes through the amplifier circuit 5 after decreasing to L1. The width of the L1 and L2 levels is usually set larger than the instantaneous fluctuation width of the RSSI level, and is set to a fixed value so that the instantaneous fluctuation width of the RSSI does not affect the AGC switching.
[0004]
When the AGC switching is not performed, the reception dynamic range on the amplifier side is L2−Lmin, and the reception dynamic range on the attenuator side is Lmax−L1. Usually, L2−Lmin = Lmax−L1.
[0005]
[Problems to be solved by the invention]
Since the hysteresis width L2-L1 of the conventional switchable AGC circuit is fixed and set in accordance with the worst value of the instantaneous fluctuation of RSSI, when the instantaneous fluctuation width of RSSI is small, the dynamic range (high reception signal level) In terms of the range).
Further, in order to prevent a bit error from occurring due to discontinuity of the received signal level at the time of circuit switching, it is necessary to make the AGC switching hysteresis width larger than the worst value of the RSSI instantaneous fluctuation width.
[0006]
The present invention provides an AGC control device and an AGC control method capable of expanding the reception dynamic range when the RSSI instantaneous fluctuation width is small by switching the AGC circuit according to the instantaneous fluctuation width of RSSI. Objective.
[0007]
[Means for Solving the Problems]
A gain control device according to the present invention includes an attenuation circuit unit that attenuates a received signal using any one of a plurality of different attenuation amounts;
Detecting the received signal level of the received signal, using the detected received signal level, calculating the fluctuation amount of the received signal level, and selecting one attenuation amount from the plurality of attenuation amounts based on the fluctuation amount, And a control unit that controls the received signal level by operating the attenuation circuit unit based on the selected one attenuation amount.
[0008]
The attenuation circuit unit attenuates a received signal using at least a first attenuation amount and a second attenuation amount larger than the first attenuation amount,
The control unit selects the first attenuation amount when the fluctuation amount is larger than a predetermined fluctuation reference value, and selects the second attenuation amount when the fluctuation amount is smaller than the predetermined fluctuation reference value. It is characterized by selecting.
[0009]
The control unit calculates an average level by averaging a plurality of received signal levels of signals received within a predetermined period, and controls the received signal level using the average level and the fluctuation amount. To do.
[0010]
The gain control device further includes an amplifier circuit that amplifies the received signal,
The attenuation circuit unit attenuates a received signal using at least a first attenuation amount and a second attenuation amount larger than the first attenuation amount,
The control unit selects the amplifier circuit when the average level is smaller than a predetermined average reference value, and the average level is larger than a predetermined average reference value and the fluctuation amount is larger than a predetermined fluctuation reference value. Selecting a first attenuation amount, and selecting the second attenuation amount when the average level is greater than a predetermined average reference value and the variation amount is smaller than a predetermined variation reference value. To do.
[0011]
The attenuation circuit section includes a plurality of circuits having different attenuation amounts,
The control unit selects one circuit from the plurality of circuits based on the fluctuation range, and controls the reception level using the selected circuit.
[0012]
The attenuation circuit unit includes an attenuation adjustment unit that adjusts the attenuation, and
A circuit for attenuating the received signal using the attenuation adjusted by the attenuation adjustment unit,
The control unit outputs the selected attenuation amount to the attenuation amount adjustment unit,
The attenuation adjustment unit adjusts the attenuation based on the attenuation input from the control unit.
[0013]
The attenuation amount adjusting unit adjusts the attenuation amount in stages.
[0014]
The control unit expands a range of a received signal level of a received signal by selecting one attenuation amount from a plurality of attenuation amounts based on the variation amount.
[0015]
A gain control method according to the present invention is a gain control method including an attenuation circuit unit that attenuates a received signal using any one of a plurality of different attenuation amounts.
Detect the received signal level of the received signal,
Using the detected received signal level, calculate the fluctuation amount of the received signal level,
Based on the calculated fluctuation amount, select one attenuation amount from the plurality of attenuation amounts,
The received signal level is controlled using the selected one attenuation amount and the attenuation circuit unit.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
In this embodiment, an amplification circuit that amplifies the reception signal, a plurality of attenuation circuits that attenuate the reception signal (a plurality of attenuation circuits are referred to as attenuation circuit units), a reception signal level (RSSI), and an amplification circuit An AGC control device (gain control device) including a control unit that switches to an attenuation circuit will be described.
The control unit (1) switches the switch so that the received signal passes through the amplifier circuit when the RSSI average level is small, and (2) the RSSI average level is larger than a predetermined average reference value and the RSSI instantaneous When the fluctuation range is larger than the predetermined average fluctuation value, switching is performed so that the received signal passes through the conventional attenuation circuit. (3) The RSSI average level is larger than the predetermined average reference value and the RSSI instantaneous When the fluctuation range is smaller than the predetermined fluctuation value, the switch is switched so that the received signal passes through the attenuation circuit having a larger attenuation amount. By enabling reception of a signal having a high RSSI average level, a wider dynamic range can be obtained.
This will be described below with reference to the drawings.
[0017]
FIG. 1 shows a circuit configuration of an AGC control apparatus according to Embodiment 1 of the present invention. The same components as those in the conventional example of FIG.
In FIG. 1, 1 is a receiving antenna, 2a and 2b are receiving circuits, and 3 is a receiving band limiting filter. Of the received signals that have passed through the reception band limiting filter 3, one enters the switch 4 a and the other enters the control unit 8. The control unit 8 performs RSSI detection and AGC circuit switching. The switches 4a and 4b are switches for switching the AGC circuit. Between the switch 4a and the switch 4b, as an AGC circuit, the amplifier circuit 5 and the attenuation circuits 6a, 6b,. . . , 6n. After passing through these circuits, the received signal finally enters the demodulator 7. In the example of FIG. 1, the case where the attenuation circuit 6a and the attenuation circuit 6b are provided (when n = 2) is shown.
[0018]
The control unit 8 detects a received signal level (RSSI) from the received signal. Further, the control unit 8 calculates the RSSI average level (average level of the received signal level) and the RSSI instantaneous fluctuation range (variation amount) based on the detected received signal level.
The RSSI average level is an average value of received signal levels of a plurality of signals received within a predetermined period.
The RSSI instantaneous fluctuation range is a difference between at least two received signal levels. The received signal level for calculating the fluctuation range is calculated from an arbitrary plurality of received signal levels, and the arbitrary received signal levels may be received signal levels of signals received in a predetermined period. .
[0019]
FIG. 2 shows a circuit switching hysteresis characteristic of the AGC control device according to the first embodiment of the present invention.
The dynamic range of the amplifier circuit 5 is L2-L0, the dynamic range of the attenuation circuit 6a is L3-L1, and the dynamic range of the attenuation circuit 6b is L5-L4. Further, the AGC switching hysteresis width when the amplification circuit 5 and the attenuation circuit 6a are used is L2-L1, and the AGC switching hysteresis width when the amplification circuit 5 and the attenuation circuit 6b are used is L2-L4.
[0020]
The reception signal captured by the reception antenna 1 passes through the reception circuit 2 a and passes through the reception band limiting filter 3. One enters the AGC circuit changeover switch 4a, and the other enters the control unit 8 including the RSSI level detection unit.
[0021]
When the detected RSSI average level or RSSI instantaneous fluctuation range is within the range of L0 to L1, the control unit 8 controls the switches 4a and 4b to select the amplifier circuit 5 as the AGC circuit.
[0022]
When the detected RSSI average level or RSSI instantaneous fluctuation range is within the range of L1 to L4, the control unit 8 selects either the amplifier circuit 5 or the attenuation circuit 6a. In actual operation, the current AGC circuit (currently selected circuit) is maintained.
[0023]
When the detected RSSI average level or RSSI instantaneous fluctuation range is within the range of L4 to L2, the control unit 8 selects either the amplifier circuit 5 or the attenuation circuit 6b. The actual operation is to maintain the current AGC circuit.
[0024]
When the detected RSSI average level or RSSI instantaneous fluctuation range is within the range of L2 to L3 and the RSSI instantaneous fluctuation range is larger than L2 to L4, the control unit 8 performs AGC switching so as to select the attenuation circuit 6a. Operate.
[0025]
When the detected RSSI average level or RSSI instantaneous fluctuation range is within the range of L2 to L3 and the RSSI instantaneous fluctuation range is smaller than L2 to L4, the control unit 8 performs AGC switching so as to select the attenuation circuit 6b. Operate.
[0026]
As described above, according to the first embodiment, when the RSSI instantaneous fluctuation is larger than L2-L4, the conventional reception dynamic range L3-L0 is secured, but when the RSSI instantaneous fluctuation is smaller than L2-L4. The reception dynamic range can be expanded to L5-L0.
As described above, the AGC control device according to the present invention detects the RSSI instantaneous fluctuation range, and when the RSSI absolute level is large and the fluctuation range is large, the conventional attenuation circuit having the switching hysteresis characteristic is used. When the RSSI absolute level is large and the fluctuation range is small, an attenuation circuit that enables input reception of a signal with a high reception level is used to widen the reception dynamic range. It is.
[0027]
As described above, the AGC control device (gain control device) of this embodiment includes an amplifier circuit that amplifies a low reception input voltage, a plurality of attenuation circuits (attenuation circuit units) that attenuate a high reception input voltage, and a reception circuit. It has a control unit that performs gain switching according to the signal level, and the control unit monitors the fluctuation range of the received signal level and, when the fluctuation range is large, has a switching characteristic with a large hysteresis by using a circuit with a small attenuation. It is characterized in that the occurrence of a bit error due to a fluctuation in the electric field is suppressed, and when the fluctuation range is small, a circuit having a large attenuation is used to provide a switching characteristic with a small hysteresis to widen the dynamic range of the received input voltage.
[0028]
Embodiment 2. FIG.
In this embodiment, an amplification circuit that amplifies a reception signal, one variable attenuation circuit (attenuation circuit unit) that attenuates the reception signal, and a reception signal level (RSSI) are detected, and switching between the amplification circuit and the attenuation circuit is performed. An AGC control device (gain control device) including a control unit that performs the above will be described.
A wider dynamic range can be obtained by largely controlling the attenuation and enabling reception of a signal having a high RSSI average level.
[0029]
FIG. 3 shows a second embodiment of the present invention.
In the first embodiment, the attenuation circuits 6a, 6b,. . . , 6n are provided with n types of circuits having different attenuation amounts, but instead of them, one variable attenuation circuit 6 is provided. This variable attenuation circuit can change the attenuation amount stepwise or continuously by external control.
[0030]
Although not clearly shown in FIG. 3, the variable attenuation circuit 6 includes an attenuation amount adjustment unit that adjusts the attenuation amount, and a circuit that attenuates a received signal using the attenuation amount adjusted by the attenuation amount adjustment unit.
The control unit 8 outputs the selected attenuation amount to the attenuation amount adjustment unit, and the attenuation amount adjustment unit adjusts the attenuation amount based on the attenuation amount input from the control unit.
The control unit 8 may select one attenuation amount from a plurality of predetermined attenuation amounts, may calculate the attenuation amount based on the RSSI instantaneous fluctuation range, or may use other methods to reduce the attenuation amount. May be determined. The control unit 8 outputs the attenuation amount determined by any method to the attenuation adjustment unit as the selected attenuation amount.
[0031]
FIG. 4 shows a circuit switching hysteresis characteristic of the AGC control device according to the second embodiment of the present invention.
The dynamic range of the amplifier circuit 5 is L2-L0, the dynamic range example a of the variable attenuation circuit 6 is L3-L1, and the dynamic range example b of the variable attenuation circuit is L5-L4. Further, the AGC switching hysteresis width when the example a of the amplifier circuit 5 and the variable attenuation circuit 6 is used is L2-L1, and the AGC switching hysteresis width when the example b of the amplifier circuit 5 and the variable attenuation circuit 6 is used is L2-L1. L4.
[0032]
In the second embodiment, instead of performing the AGC control by switching the attenuation circuit in the first embodiment, the attenuation amount of the attenuation circuit is externally controlled stepwise or continuously in the same manner as in the first embodiment. An effect is obtained.
[0033]
As described above, the AGC control device (gain control device) of this embodiment includes an amplification circuit that amplifies a low reception input voltage, and an attenuation circuit (attenuation circuit unit) that can attenuate the high reception input voltage and change the attenuation amount. And a control unit that performs gain switching according to the received signal level. The control unit monitors the fluctuation range of the received signal level, and when the fluctuation range is large, the circuit uses a circuit with low attenuation to switch large hysteresis. It has characteristics to suppress the occurrence of bit errors due to electric field fluctuations, and when the fluctuation range is small, a circuit with a large attenuation is used to change the attenuation stepwise or continuously according to the fluctuation range, and optimal hysteresis switching characteristics To increase the dynamic range of the received input voltage.
[0034]
Embodiment 3 FIG.
In the above-described embodiment, the case where a plurality of attenuation circuits having different attenuation amounts are used and the case where a variable attenuation circuit is used as the attenuation circuit unit that attenuates signals received using a plurality of different attenuation amounts have been described. However, the attenuation circuit unit is not limited to the above case, and may have other configurations.
If the control unit 8 selects one attenuation amount from a plurality of attenuation amounts based on the variation amount of the received signal level, and controls the received signal level using the selected one attenuation amount, It does not matter if it is something else. Moreover, the apparatus and method which control the attenuation | damping of a signal using the calculated attenuation amount may be sufficient as the control part 8 calculating attenuation amount based on the variation | change_quantity.
[0035]
【The invention's effect】
As described above, according to the present invention, not only the AGC control based only on the average level of RSSI but also a circuit with a small attenuation is selected when the RSSI fluctuation range is large, and the attenuation is large when the RSSI fluctuation range is small. By optimizing the switching of the AGC circuit such as selecting a circuit, the reception dynamic range can be widened.
[0036]
The reception dynamic range can be expanded by using a plurality of attenuation circuits having different attenuation amounts.
[0037]
The reception dynamic range can be expanded by using a variable attenuation circuit capable of adjusting the attenuation.
[0038]
Further, the attenuation amount can be switched stepwise or continuously by the variable attenuation circuit.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a circuit configuration of an AGC control apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing a circuit switching hysteresis characteristic of the AGC control device according to the first embodiment of the present invention.
FIG. 3 is a block diagram showing a circuit configuration of an AGC control apparatus according to Embodiment 2 of the present invention.
FIG. 4 is a diagram showing a circuit switching hysteresis characteristic of an AGC control device according to Embodiment 2 of the present invention.
FIG. 5 is a block diagram showing a circuit configuration of an AGC control device in a conventional example.
FIG. 6 is a diagram showing a circuit switching hysteresis characteristic of an AGC control device in a conventional example.
[Explanation of symbols]
1 receiving antenna, 2a to 2b receiving circuit, 3 receiving band limiting filter, 4a, 4b AGC circuit changeover switch (switch), 5 amplifying circuit, 6 variable attenuating circuit, 6a, 6b attenuating circuit, 7 demodulating unit, 8 controlling unit ( A control unit including an RSSI detection unit).

Claims

An attenuation circuit that attenuates a received signal using any one of a plurality of different attenuations;
Detecting the received signal level of the received signal, using the detected received signal level, calculating the fluctuation amount of the received signal level, and selecting one attenuation amount from the plurality of attenuation amounts based on the fluctuation amount, A control unit for controlling the received signal level by operating the attenuation circuit unit based on the selected one attenuation amount ;
An amplification circuit for amplifying the received signal,
The attenuation circuit unit attenuates a received signal using at least a first attenuation amount and a second attenuation amount larger than the first attenuation amount,
The control unit calculates an average level by averaging a plurality of received signal levels of signals received within a predetermined period, and when the average level is smaller than a predetermined average reference value, selects the amplification circuit, When the average level is larger than a predetermined average reference value and the fluctuation amount is larger than a predetermined fluctuation reference value, the first attenuation amount is selected, and the average level is larger than the predetermined average reference value and the fluctuation amount. The gain control device is characterized in that the second attenuation is selected when is smaller than a predetermined fluctuation reference value .

An attenuation circuit unit that attenuates a received signal using any one of a plurality of different attenuation amounts;
The received signal level of the received signal is detected, and using the detected received signal level, the fluctuation amount of the received signal level is calculated. Based on the fluctuation amount, the switching hysteresis characteristic of the attenuation circuit unit is a predetermined switching hysteresis. A control unit that controls a received signal level by selecting one attenuation amount from the plurality of attenuation amounts so as to have a characteristic and operating the attenuation circuit unit based on the selected one attenuation amount. A characteristic gain control apparatus.

The attenuation circuit unit attenuates a received signal using at least a first attenuation amount and a second attenuation amount larger than the first attenuation amount,
The control unit selects the first attenuation amount when the fluctuation amount is larger than a predetermined fluctuation reference value, and selects the second attenuation amount when the fluctuation amount is smaller than the predetermined fluctuation reference value. The gain control device according to claim 2, wherein:

4. The gain control device according to claim 3, wherein the predetermined fluctuation reference value is a switching hysteresis width of the attenuation circuit unit when the control unit selects the second attenuation amount.

The control unit calculates an average level by averaging a plurality of received signal levels of signals received within a predetermined period, and controls the received signal level using the average level and the fluctuation amount. The gain control device according to claim 2 .

The attenuation circuit section includes a plurality of circuits having different attenuation amounts,
Wherein the control unit, based on the fluctuation range, select circuit according to one from the plurality of circuits, according to claims 1, characterized in that to control the reception level using the circuit selected to 5 or Gain control device.

The attenuation circuit unit includes an attenuation adjustment unit that adjusts the attenuation, and
A circuit for attenuating the received signal using the attenuation adjusted by the attenuation adjustment unit,
The control unit outputs the selected attenuation amount to the attenuation amount adjustment unit,
The attenuation amount adjusting section, gain control device according to any one of claims 1-5, characterized in that to adjust the attenuation amount based on the attenuation amount input from the control unit.

8. The gain control apparatus according to claim 7 , wherein the attenuation amount adjusting unit adjusts the attenuation amount in a stepwise manner.

In a gain control method including an attenuation circuit unit that attenuates a received signal using any one of a plurality of different attenuation amounts,
Detect the received signal level of the received signal,
Using the detected received signal level, calculate the fluctuation amount of the received signal level,
Based on the calculated variation amount, selects one attenuation from above SL more attenuation as switching hysteresis characteristic of the damping circuit is a predetermined switching hysteresis characteristic,
A gain control method, comprising: controlling a received signal level using a selected attenuation amount and the attenuation circuit unit.