JP3875657B2 - Signal processing apparatus and signal processing method - Google Patents

Description

【００２０】
式（１）において、ｘは観測対象信号、αは相関周波数、Ｅ［ ］はアンサンブル平均を示す。周期定常性算出部３１は式（１）の演算を実施することにより複数の信号系列を生成する。なお式（１）のようなアンサンブル平均を求めることは、実装上の観点からは容易ではない。よって本実施形態では、或る有限区間の平均値により式（１）を代替する。平均化される区間の長さ、すなわち観測対象信号の範囲、および相関周波数は制御器４０により設定される。
【００２１】
図４は、周期定常性算出部３１から出力される信号系列の例を示す図である。すなわち、図４に示される系列がＣＡＦの信号系列である。ＣＡＦ信号系列は、時間軸（横軸）に対して周期的なピークを示す。
【００２２】
このＣＡＦ信号系列の時間応答を周波数領域に変換した量として、ＣＳＦ（Cyclic Spectral Function）が定義される。ＣＳＦは次式（２）のように定義される。すなわちＣＳＦはＣＡＦ信号系列をフーリエ変換することにより得られ、図１のＦＦＴ部３３は周期定常性算出部３１からの信号系列に式（２）の演算を施すことによりＣＳＦ信号系列を生成する。
【００２３】
【数２】

【００２４】
図５は、図１のＦＦＴ部３３から出力されるＣＳＦの信号系列の一例を示す図である。この信号系列を、例えば強度（縦軸）の０．１５を閾値として識別することにより無線周波数信号の変調多値数を推定することが可能になる。図５は良好に分離する２つのピークを示し、従って図４のＣＡＦ系列を示す無線周波数信号の多値数が２であることが読み取れる。
【００２５】
仮に、観測対象信号としてＭ値でＦＳＫ変調された無線周波数信号を想定する。Ｍ値のＦＳＫ変調信号は、伝送符号に基づいて搬送波周波数を例えば次式（３）のいずれかに変化させることにより生成される。
【数３】

【００２６】
搬送波周波数は互いに発振周波数の異なる複数の発振器の出力を切り替え選択することによっても変化させることができるが、周波数の急激な切り替えはスペクトルの拡大を生じさせる。このため一般には、位相の連続性を保てるＣＰ（Continuous Phase）ＦＳＫが用いられる。
【００２７】
搬送波の位相は、過去の周波数偏移の積分として表現される。よってＣＰＦＳＫの位相軌跡を位相木（位相ダイヤグラム）により表現することができる。位相木は時間経過、つまり観測時間と共に増大するが、搬送波の位相は０から２πの範囲において循環する。よって２πを法（モジュロ）とすることにより位相木は縮退し、所定の集合要素を巡回的に変化するようになる。上記で述べた無線周波数信号の周期定常性は、この周期性の特徴が相関演算によって出現したものである。
【００２８】
図６は、信号処理部３２を機能させない場合にＦＦＴ部３３から出力されるＣＳＦの応答を示す図である。図６における観測対象信号は４値ＦＳＫである。図６から観測されるように、Ｍ値ＦＳＫのＣＳＦをプロットしたグラフにはＦＳＫの多値数Ｍに対応するピークが出現する。
【００２９】
図７は、８値ＦＳＫ信号に対して信号処理部３２を機能させない場合にＦＦＴ部３３から出力されるＣＳＦの応答を示す図である。図６および図７から分かるように、信号処理部３２を機能させない場合には変調多値数が大きくなるに従ってＣＳＦ ｉｎｄｅｘの中央付近が隆起し、多値数の判定が難しくなる。すなわち、ＣＳＦから多値数を判定するには図６に示される４値程度が限度であり、変調多値数が増えるほどにＣＳＦ系列の分離度が低下し、変調多値数を推定することが困難になる。なおこれは、変調多値数が大きくなるに従って、多値数Ｍに対応するピークのレベルが下がり、中央の擾乱成分が目立つようになるためである。
【００３０】
そこで本実施形態では、信号処理部３２を機能させることによりＣＡＦ ｉｎｄｅｘの時間軸原点近傍の信号系列をゼロ化するようにする。図１の周期定常性算出部３１から出力される信号は、式（１）に示される信号系列である。この系列は例えば図４のような形状を示す。図４のように、各系列はそれぞれ明確なピークを有しておりそれぞれ区別することができるので、周期定常性算出部３１から出力される系列をｘ（ｉ），（ｉ＝０，１，…，Ｎ−１）とする。図４においては、ｉは横軸（ＣＡＦ ｉｎｄｅｘ）の各数値に対応する。
【００３１】
信号処理部３２は、ｘ（ｉ）に対して例えば次式（４）に示す処理を実施する。
【数４】

【００３２】
すなわち信号処理部３２は、時間軸原点（ｉ＝０）からｉ＜Ｄまでの範囲に有る信号系列を０で置換し、ｉ≧Ｄの範囲に有る系列をそのままＦＦＴ部３３に出力するという処理を行う。
【００３３】
図８は信号処理部３２を機能させた場合、つまり信号処理部３２に上記のような処理を実施させた場合にＦＦＴ部３３から出力されるＣＳＦの応答を示す図である。図８における観測対象信号は４値ＦＳＫであり、図８のグラフは図６と比較できる。図８から観測されるように、Ｍ値ＦＳＫのＣＳＦをプロットしたグラフには図６に比べてさらに良好に分離したピークが出現する。
【００３４】
図９は、８値ＦＳＫ信号に対して信号処理部３２を機能させた場合にＦＦＴ部３３から出力されるＣＳＦの応答を示す図である。図９においては、図７のＣＳＦ ｉｎｄｅｘのグラフ中央付近に見られた隆起が無くなり、変調多値数に対応するピークが良好に分離して現れている。従ってこのピークをカウントすることにより、変調多値数を正確かつ容易に推定することが可能になる。
【００３５】
図８や図９に示したような波形が観測されるのは、受信状態が良好な場合などにおいてである。しかしながら、実際には必ずしも良好な受信状態下にある訳ではなく、観測対象信号は雑音や無線伝搬路の歪によって劣化している。
【００３６】
図１０は、雑音などの影響を受けた場合のＣＳＦの応答の例を示す図である。図１０の（ａ）、（ｂ）とも、変調多値数が４の場合の例を示している。図１０から、変調多値数に対応するピークのレベルにばらつきが生じ、さらに、ピークに広がりが生じていることが確認できる。
【００３７】
このような状況においても、変調多値数に対応するピークを検出するためには、マシン側の処理によって、グルーピング処理を施すことが有効である。グルーピング処理を行うことで、変調多値数Ｍの推定精度を向上することができる。
【００３８】
図１１は、変調多値数検出部３４におけるグルーピング処理につき説明するための概念図である。図示されるように、ＣＳＦ信号系列は複数のグループに区分することができる。これらのグループの数をカウントすることで、無線周波数信号の変調多値数Ｍを推定することができる。
【００３９】
図１２は、変調多値数検出部３４によるグルーピング処理をより具体的に説明するための概念図である。図１２において各ＣＳＦ系列はｐ［ｉ］で示される。このうち値の最も大きい系列をＭａｘｐ［ｉ］で示す。さらに、Ｍａｘｐ［ｉ］よりも値の小さい数値αを導入し、これをＭａｘｐ［ｉ］から減算した値Ｍａｘｐ［ｉ］−αを、グルーピングの際の判定基準レベルとする。
【００４０】
そうすると、各系列は、Ｍａｘｐ［ｉ］−αを境界として０または１のいずれかの状態に対応する。これをｑ［ｉ］で示す。図示されるようにｑ［ｉ］は、０（系列が基準値以下）が連続するなかで、１（系列が基準値以上）が連続する部分が生じる。これを例えばソフトウェア処理などによりグルーピングの指標とすることで、例えば図１２においてはグループ１〜グループ４の４つのグループに分けることができる。これにより、変調多値数Ｍが４であることが判断される。
【００４１】
このように本実施形態では、無線周波数信号をダウンコンバートしたＢＢ信号の周期定常性を周期定常性算出部３１により算出し、ＣＡＦ ｉｎｄｅｘの複数の信号系列を生成する。そして、信号処理部３２によりこれらの信号系列のうち時間軸原点から所定の範囲内に有る系列を０に置換し、ＦＦＴ部３３に入力する。これにより得られるＣＳＦ ｉｎｄｅｘの周期定常スペクトルを変調多値数検出部３４により所定の判定基準レベルのもとで２つの状態に分別し、無線周波数信号の変調多値数を検出するようにしている。
【００４２】
このように、ＣＡＦ ｉｎｄｅｘの信号系列のうち時間軸原点近傍の系列を０で置換することで、ＣＳＦ ｉｎｄｅｘの信号系列グラフの中央付近に隆起が生じることを防止し、ＣＳＦ ｉｎｄｅｘの信号系列を良好に分離することができる。０に置換すべきＣＡＦ ｉｎｄｅｘの範囲は、制御器４０により任意に変更することができる。このようなことから本実施形態によれば、いかなる無線周波数信号に対してもその変調多値数Ｍを正確かつ容易に推定することが可能になる。
【００４３】
（第２の実施形態）
図１３は、本発明に係わる信号処理装置の第２の実施形態を示すブロック図である。なお図１３において図１と共通する部分には同一の符号を付して示し、ここでは異なる部分についてのみ説明する。図１３において受信部２０から出力されるＢＢ信号は、信号分析部６０の周波数オフセット検出部６１、周波数オフセット補正部６２、およびセレクタ６３に入力される。周波数オフセット検出部６１はＢＢ信号の周波数オフセットを検出し、その結果に基づいて、周波数オフセット補正部６２によりＢＢ信号の周波数オフセットが補正される。
【００４４】
セレクタ６３は、周波数オフセットを補正しないＢＢ信号、または周波数オフセットが補正されたＢＢ信号のいずれかを選択し、検波器６４および周期定常スペクトル算出部６６に入力する。いずれの信号を選択するかは信号分析部６０の制御部６８により制御される。検波器６４は入力されたＢＢ信号を検波し、その出力を統計量算出部６５に入力する。統計量算出部６５は、検波器６４の出力信号に係わる平均、分散などの統計量を算出する。本実施形態では、統計量算出部６５は観測対象信号の受信包絡の分散を算出する。得られた統計量は周期定常スペクトル算出部６６に入力される。
【００４５】
周期定常スペクトル算出部６６は、図１の周期定常性算出部３１、信号処理部３２、およびＦＦＴ部３３を備え、第１の実施形態で述べた手順により、入力されたＢＢ信号の周期定常スペクトルを求める。周期定常スペクトル算出部６６から出力されるＣＳＦ信号系列は変調多値数検出部３４に渡され、アンテナ１０に到来する無線周波数信号の変調多値数Ｍが推定される。
【００４６】
本実施形態においては、周期定常スペクトル算出部６６における信号処理部３２の処理の実行／停止（すなわち信号処理部３２のオン／オフ）のいずれかを、統計量算出部６５により得られる受信包絡の分散に基づいて決定するようにする。すなわち、ＣＡＦ信号系列の一部を０で置換するか／否かという判断が、受信信号の受信包絡の分散に基づいて制御部６８により決定される。
【００４７】
周期定常スペクトル算出部６６は、統計量算出部６５から通知される受信包絡の分散値を、予め設定された閾値と比較する。そして周期定常スペクトル算出部６６は、分散値が閾値よりも小さい場合には信号処理部３２を動作させ、それ以外の場合には信号処理部３２を動作させないように機能する。なお、統計量算出部６５において分散値と閾値とを比較し、その結果に応じて、信号処理部３２のオン／オフを切り替える制御信号を統計量算出部６５から周期定常スペクトル算出部６６に与えるようにしても良い。
【００４８】
このように観測対象信号の受信包絡の統計量を用いることにより、定包絡変調方式であるＦＳＫにより変調された無線周波数信号を検出することができる。この情報を用いることにより、変調多値数をより効率的に検出することが可能となる。すなわち本実施形態によれば、上記第１の実施形態により得られる効果に加え、事前の情報を要すること無く変調多値数Ｍを推定することができる。さらに、無線周波数信号のタイミング同期が達成されていない状況においても、変調多値数の推定精度の向上を図ることができる。
【００４９】
（さらに詳しい説明）
次に、上記第１および第２の実施形態における処理につきさらに詳しく説明する。図１４は、無線周波数信号の周期定常性の時間応答の他の例を示す図である。図１４の系列の時間応答をフーリエ変換して周波数領域信号に変換したすることにより周期定常スペクトルが得られ、周期定常スペクトルのピーク数をカウントすることで変調多値数推定することができる。
【００５０】
図１４に示した時間応答から、周期的な変動が観測される。この周期性が、周波数領域における線スペクトル成分となる。図１４によれば、横軸が０から１の領域において周期性の乱れが観測される。この時間領域における周期性の乱れは、周波数領域信号にも影響を与え、周期定常スペクトルに劣化を引き起こす。上記実施形態では、この横軸の原点近傍をゼロ化することにより周期性の乱れの影響を回避するようにする。
【００５１】
なお、図１４の横軸は信号伝送速度により正規化されているが、装置の実施に際しては観測対象信号の信号伝送速度は未知であることから、周期性を乱す範囲としての０から１に対応する領域を厳密に把握することは難しい。つまり、ゼロ置換する領域を厳密に把握することは難しい。
【００５２】
しかしながら本発明の目的は、周期性を乱す部分の影響を大まかに除去できれば良く、従ってゼロ化すべき領域を厳密に決定する必要はない。つまり、時間応答の０（原点）から全体の１／４をゼロ化したり、時間応答の０から全体の１／８をゼロ化したりすることで、充分な効果を得ることができる。すなわち、周期性を乱す部分である時間軸原点近傍の時間応答の影響を回避することができれば充分であり、従ってゼロ化する領域を厳密に制限する必要はない。なお図６に示されるように、多値数が４値程度であれば、時間応答の０近傍で生じる周期性の乱れの影響は少ない。これは、ＣＳＦ ｉｎｄｅｘの０近傍の隆起に比べ、多値数に相当する線スペクトルのレベルが大きいことによる。
【００５３】
図１５は、信号の諸元を観測する機能を持つ信号処理装置のブロック構成図である。図１５において、受信部２０は観測対象信号を受信し、ＢＢ信号を次段の信号諸元検出部７０に出力する。信号諸元検出部７０は、制御器４０の指示に基づき観測対象信号の変調に関する諸元を検出するための信号処理を実施する。信号諸元検出部７０により検出された各パラメータは、制御器４０の指示に基づき表示／インタフェース部３６に渡される。表示／インタフェース部３６は、信号諸元検出部７０により検出された各パラメータを視覚的に表示する。また制御器４０は、受信部２０、信号諸元検出部７０、表示／インタフェース部３６に対する制御を統括的に実施する。また制御器４０は、表示／インタフェース部３６から入力された指示に基づいて信号処理装置の動作を変更する。
【００５４】
図１６は、図１５の信号諸元検出部７０の一構成例を示すブロック図である。図１６において、受信部２０から出力されるＢＢ信号は、変調多値数検出部７１、変調形式検出部７２、伝送速度検出部７３、諸パラメータ検出部７４にそれぞれ入力される。変調多値数検出部７１の処理機能は上記で説明したのと同様である。変調形式検出部７２は、ＡＳＫ、ＰＳＫ、ＦＳＫなどの、観測対象信号の変調形式を検出し、その結果を変調多値数検出部７１および表示部／インタフェース部３６に出力する。伝送速度検出部７３は観測対象信号の信号伝送速度を検出し、その結果を変調多値数検出部７１および表示部／インタフェース部３６に出力する。諸パラメータ検出部７４は、観測対象信号に関する他のパラメータを検出する。各部７５，６５，３１，６２，７６，７４，７７に対する制御は制御部７８により統括的に実施される。
【００５５】
上記構成においては、変調形式検出部７２から出力される信号、および伝送速度検出部７３から出力される信号がともに変調多値数検出部７１に入力されることが特徴的である。このような構成とすることで、本発明の目的とする変調多値数の検出をより効率的に実施することが可能となる。
【００５６】
すなわち変調多値数検出部７１に、観測対象信号の伝送速度および変調形式を通知することにより、図１４に示されるような周期性を乱す領域をより的確に把握することができる。従って上記構成によれば、特にＦＳＫ変調方式により変調された無線周波数信号の多値数をより効率的に検出することが可能になる。
【００５７】
図１７は、信号の諸元を観測する機能を持つ信号処理装置の他の構成を示すブロック図である。なお図１７において図２、図３、図１６と共通する部分には同一の符号を付して示し、ここでは異なる部分についてのみ説明する。図１７の信号帯域特定部２３において観測対象らしき信号が観測された場合、すなわち電力測定部２３３において予め設定された電力以上の信号が観測された場合には、その信号を選択すべく帯域変換部２４の通過帯域が変換され、観測対象信号がフィルタ部２６に渡される。フィルタ部２６は、帯域幅推定部２６１により観測対象信号の帯域幅を大まかに推定し、その結果に応じてフィルタ２６２の帯域を設定して対象信号をフィルタリングする。フィルタ２６２を通過した観測対象信号は信号諸元検出部７０に入力される。
【００５８】
フィルタ部２６から信号諸元検出部７０に入力される観測対象信号は、ピーク検出部７５、統計量算出部６５、周期定常性算出部３１、シンボルクロック抽出部７６、諸パラメータ検出部７４にそれぞれ入力される。ピーク検出部７５は観測対象信号のピークを検出する。シンボルクロック抽出部７６は、観測対象信号のシンボルクロックを抽出する。
【００５９】
各部７５，６５，３１，７６，７４により検出された各パラメータは諸元分類処理部７７に与えられる。ただし周期定常性算出部３１から出力される信号系列は信号処理部３２を経て一部ゼロ化処理され、変調多値数データが取得される。この変調多値数データが諸元分類処理部７７に与えられる。これらの各パラメータは参照データテーブル８０にデータベース化される。また、過去に取得された諸パラメータを参照データテーブル８０から読み出し、参照することにより、信号諸元の推定性能を向上させることが可能となる。
【００６０】
なお、本発明は上記実施の形態に限定されるものではない。
例えば周期定常性は、式（１）を変形した次式（５）によっても算出することができる。
【数５】

【００６１】
式（５）の評価尺度が他の分析信号処理で必要となる場合には、式（５）の周期定常性を用いることで、同じデータを他の分析信号処理と共用することが可能となるメリットがある。
【００６２】
また上記実施形態では、無線周波数信号をダウンコンバートしてベースバンド信号に変換するようにしているが、これに代えて中間周波数信号に変換するようにしても良い。
また上記実施形態では、ＣＡＦ信号系列の一部を０に置換するようにしているが、これに代えて、０でない一定値に置換するようにしても良い。
さらに本発明は、実施段階ではその要旨を逸脱しない範囲で構成要素を変形して具体化できる。また、上記実施形態に開示されている複数の構成要素の適宜な組み合わせにより、種々の発明を形成できる。例えば、実施形態に示される全構成要素から幾つかの構成要素を削除してもよい。さらに、異なる実施形態にわたる構成要素を適宜組み合わせてもよい。
【００６３】
【発明の効果】
以上詳しく述べたように本発明によれば、変調多値数を高い精度で推定することの可能な信号処理装置および信号処理方法を提供することができる。
【図面の簡単な説明】
【図１】 本発明に係わる信号処理装置の第１の実施の形態を示すブロック図。
【図２】 図１の受信部２０の一構成例を示す図。
【図３】 図２の信号帯域特定部２３の一構成例を示す図。
【図４】 図１の周期定常性算出部３１から出力される信号系列の例を示す図。
【図５】 図１のＦＦＴ部３３から出力されるＣＳＦの信号系列の一例を示す図。
【図６】 ４値ＦＳＫ信号に対して、信号処理部３２を機能させない場合にＦＦＴ部３３から出力されるＣＳＦの応答を示す図。
【図７】 ８値ＦＳＫ信号に対して、信号処理部３２を機能させない場合にＦＦＴ部３３から出力されるＣＳＦの応答を示す図。
【図８】 ４値ＦＳＫ信号に対して、信号処理部３２を機能させた場合にＦＦＴ部３３から出力されるＣＳＦの応答を示す図。
【図９】 ８値ＦＳＫ信号に対して、信号処理部３２を機能させた場合にＦＦＴ部３３から出力されるＣＳＦの応答を示す図。
【図１０】 雑音などの影響を受けた場合のＣＳＦの応答の例を示す図。
【図１１】 変調多値数検出部３４におけるグルーピング処理につき説明するための概念図。
【図１２】 変調多値数検出部３４によるグルーピング処理をより具体的に説明するための概念図。
【図１３】 本発明に係わる信号処理装置の第２の実施形態を示すブロック図。
【図１４】 無線周波数信号の周期定常性の時間応答の他の例を示す図。
【図１５】 信号の諸元を観測する機能を持つ信号処理装置のブロック構成図。
【図１６】 図１５の信号諸元検出部７０の一構成例を示すブロック図。
【図１７】 信号の諸元を観測する機能を持つ信号処理装置の他の構成を示すブロック図。
【符号の説明】
１０…アンテナ、２０…受信部、２１…アナログ処理部、２２…ＡＤＣ部、２３…信号帯域特定部、２４…帯域変換部、２５…帯域幅推定部、２６…フィルタ部、２７…制御部、３０…信号分析部、３１…周期定常性算出部、３２…信号処理部、３３…ＦＦＴ部、３４…変調多値数検出部、３５…表示部、３６…インタフェース部、４０…制御器、５０…記憶部、６０…信号分析部、６１…周波数オフセット検出部、６２…周波数オフセット補正部、６３…セレクタ、６４…検波器、６５…統計量算出部、６６…周期定常スペクトル算出部、６８…制御部、７０…信号諸元検出部、７１…変調多値数検出部、７２…変調形式検出部、７３…伝送速度検出部、７４…諸パラメータ検出部、７５…ピーク検出部、７６…シンボルクロック抽出部、７７…諸元分類処理部、８０…参照データテーブル、２３１…ＦＦＴ部、２３２…フィルタバンク形成部、２３３…電力測定部、２３４…比較器、２６１…帯域幅推定部、２６２…フィルタ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a signal processing apparatus and a signal processing method used for estimating a modulation multi-level number of a radio signal, for example.
[0002]
[Prior art]
With recent increase in communication demand, wireless communication devices are rapidly spreading. In order to maintain order and effectively use radio waves in such a situation, it is necessary to use each radio station under certain conditions. However, it is not possible to say that all wireless communication devices are operated in a condition due to a malfunction of the wireless device or illegal operation. If these are left unattended, there is a risk that the operation of a wireless device that is normally operated may be disturbed. Therefore, it is important to monitor the use of radio waves and prevent the occurrence of abnormal radio waves. For this purpose, it is necessary to estimate the specifications of radio waves transmitted from each radio station, and signal processing apparatuses for that purpose have been developed.
[0003]
This type of device targets digital modulation waves such as frequency modulation (FSK) waves, phase modulation (PSK) waves, GMSK (Gaussian filtered minimum shift keying) waves, and quadrature amplitude modulation (QAM) waves. Analyze its specifications by signal processing. In particular, it is effective to estimate the modulation multi-level number to analyze the specifications of radio waves. Conventionally, by analyzing the spectrum shape of the modulated wave with a spectrum analyzer etc., knowledge about the modulation multi-level number can be obtained. I was trying to get it. However, it cannot be said that the existing signal processing apparatus can estimate the modulation multilevel number with sufficient accuracy, and further improvement in accuracy is awaited.
[0004]
Related techniques are disclosed in the following non-patent documents. This document describes details regarding the periodicity of radio waves. The periodic steadiness of the radio wave is an index for grasping a statistic unique to the modulation signal, and is information necessary for estimating the modulation multi-level number of the radio wave.
[0005]
[Non-Patent Document 1]
Military Communications Conference 1988, MILCOM 88, pp419-424
[0006]
[Problems to be solved by the invention]
As described above, there is a demand for further improvement in accuracy of the signal processing apparatus for estimating the modulation multi-level number of radio waves. In particular, there is a need to provide a signal processing device that does not require any information in advance and can estimate the modulation multi-level number of the radio wave from the incoming radio wave itself.
[0007]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a signal processing apparatus and a signal processing method capable of estimating the modulation multi-level number with high accuracy.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a signal processing apparatus according to the present invention includes a receiving unit (for example, the antenna 10 and the receiving unit 20) that receives a multi-frequency modulated radio frequency signal and outputs a received signal; A calculation means (for example, periodic continuity calculation unit 31) that calculates periodic continuity with respect to time and outputs a plurality of signal sequences, and a signal sequence that appears in a certain range with respect to the time axis among the plurality of signal sequences. Substitution means (for example, signal processing unit 32) for substitution with a constant value, and the time response of a plurality of signal sequences including the signal series substituted with the constant value by this substitution means are converted into the frequency domain and a periodic stationary spectrum is output. Conversion means (for example, FFT section 33) and detection means (for example, modulation multilevel number detection section 34) for detecting the modulation multilevel number of the radio frequency signal from the periodic stationary spectrum are provided. The modulation multi-value number is generally a natural number of 2 or more. That is, binary modulation is included in the concept of multilevel modulation.
[0009]
By taking such means, a plurality of signal sequences having periodicity are calculated by the calculating means. The periodicity of these signal sequences is converted into the frequency domain by the converting means, and a periodic stationary spectrum is obtained. By dividing this periodic stationary spectrum into two states under a predetermined threshold, for example, the modulation multi-level number of the radio frequency signal can be detected.
[0010]
In such a configuration, replacement means is newly provided, and by converting a part of the plurality of signal series obtained by the calculation means, preferably the signal series arranged in the vicinity of the time axis origin, to a constant value, preferably zero, conversion means It is possible to increase the degree of separation with respect to the frequency of the periodic stationary spectrum obtained in the above. Therefore, it is possible to increase the accuracy of detection of the modulation multi-level number in the detection means, and it is possible to estimate the modulation multi-level number with high accuracy.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a first embodiment of a signal processing apparatus according to the present invention. This signal processing apparatus is realized as a high-speed computer or a digital signal processor (DSP). In FIG. 1, a radio frequency signal that comes from the real sky and is an observation target is captured by the antenna 10 and input to the receiving unit 20. The receiving unit 20 performs processing such as signal band detection, carrier synchronization, and timing synchronization on the radio frequency signal, generates a baseband (BB) signal, and inputs the baseband (BB) signal to the signal analysis unit 30. The receiving unit 20 also performs a moving average calculation process or the like for improving noise resistance characteristics according to the nature of the radio frequency signal.
[0012]
The signal analysis unit 30 performs various arithmetic processes on the BB signal, and analyzes the specifications of the radio frequency signal arriving at the antenna 10. The display unit 35 visually displays the analysis result by the signal analysis unit 30. The operation of the receiving unit 20, the signal analyzing unit 30, and the display unit 35 is controlled by the controller 40 under the control program stored in the storage unit 50.
[0013]
The signal analysis unit 30 includes a periodic continuity calculation unit 31, a signal processing unit 32, an FFT unit 33, and a modulation multilevel number detection unit 34.
The periodic stationarity calculation unit 31 calculates the periodic stationarity with respect to time of the BB signal, and outputs a plurality of signal sequences. The signal processing unit 32 replaces a signal sequence that appears in the vicinity of the time axis origin among the plurality of signal sequences output from the periodic continuity calculation unit 31 with a zero value. In other words, the signal processing unit 32 inputs the signal series to the FFT unit 33 in a state where a part of the plurality of signal series is zeroed. Whether or not to execute this process is determined by the controller 40. Depending on the nature of the radio frequency signal, the zeroing process may not be performed. In this case, the signal sequence obtained by the periodic steadiness calculating unit 31 is output as it is.
[0014]
The FFT unit 33 performs fast Fourier transform (FFT) processing on the signal input from the signal processing unit 32. The FFT process is a process for converting a time response of a signal into a frequency domain. The periodic stationary spectrum obtained as a result is input to the modulation multilevel number detection unit 34. The modulation multilevel number detection unit 34 classifies the periodic stationary spectrum input from the FFT unit 33 into two states based on a predetermined determination reference level, and detects the modulation multilevel number of the radio frequency signal. The detected information is displayed on the display unit 35 and notified to the user.
[0015]
The controller 40 comprehensively controls these signal processes. For example, the controller 40 performs processing such as setting of operation start / stop of the reception unit 20, setting of a detection criterion of the modulation multi-level number detection unit 34, and setting of a determination reference level.
[0016]
FIG. 2 is a diagram illustrating a configuration example of the receiving unit 20 in FIG. In FIG. 2, the radio frequency signal is subjected to analog processing such as low noise amplification by an analog processing unit 21 and then input to an ADC (Analog Digital Converter) unit 22. The ADC unit 22 converts the signal input from the analog processing unit 21 into a digital signal through processing such as sampling and quantization. The digital signal thus obtained is input to the signal band specifying unit 23 and the band converting unit 24.
[0017]
The signal band specifying unit 23 specifies the band in which the observation target signal exists from the digital signal based on the received signal. In accordance with the result, the band converting unit 24 processes a digital signal based on the received signal, converts the band of the received signal, and converts it to baseband. The BB signal thus obtained is observed by the bandwidth estimation unit 25, and the bandwidth is estimated. In accordance with the result, the BB signal is filtered by the filter unit 26 and is input to the signal analysis unit 30 in FIG. 1 in a state where the band is limited. Processing in the receiving unit 20 is controlled by the control unit 27.
[0018]
FIG. 3 is a diagram illustrating a configuration example of the signal band specifying unit 23 of FIG. The digital signal output from the ADC unit 22 is divided in the observation band by the FFT unit 231 or the filter bank forming unit 232, and the signal sequence output from the FFT unit 231 or the filter bank forming unit 232 by the subsequent power measuring unit 233. Power is measured. The measured power of each signal series is compared with a predetermined threshold by the comparator 234, and it is determined whether or not a signal exists in the observation target band.
[0019]
Next, the operation of the above configuration will be described. First, the processing of the periodic continuity calculation unit 31 in FIG. 1 will be described. The details of the periodic stationarity are disclosed in detail in Non-Patent Document 1.
Periodic stationarity is evaluated using CAF (Cyclic Autocorrelation Function) as a scale. CAF is defined as the following equation (1).
[Expression 1]

[0020]
In Expression (1), x is an observation target signal, α is a correlation frequency, and E [] is an ensemble average. The periodic stationarity calculation unit 31 generates a plurality of signal sequences by performing the calculation of the equation (1). It is not easy from the viewpoint of mounting to obtain an ensemble average such as equation (1). Therefore, in this embodiment, Formula (1) is substituted by the average value of a certain finite section. The length of the section to be averaged, that is, the range of the observation target signal and the correlation frequency are set by the controller 40.
[0021]
FIG. 4 is a diagram illustrating an example of a signal sequence output from the periodic continuity calculation unit 31. That is, the sequence shown in FIG. 4 is a CAF signal sequence. The CAF signal series shows a periodic peak with respect to the time axis (horizontal axis).
[0022]
A CSF (Cyclic Spectral Function) is defined as an amount obtained by converting the time response of the CAF signal sequence into the frequency domain. The CSF is defined as the following equation (2). That is, the CSF is obtained by performing a Fourier transform on the CAF signal sequence, and the FFT unit 33 in FIG.
[0023]
[Expression 2]

[0024]
FIG. 5 is a diagram illustrating an example of a CSF signal sequence output from the FFT unit 33 in FIG. 1. For example, by identifying 0.15 of the intensity (vertical axis) as a threshold value from this signal series, it is possible to estimate the modulation multi-level number of the radio frequency signal. FIG. 5 shows two peaks that are well separated, so it can be seen that the multi-valued number of radio frequency signals representing the CAF sequence of FIG.
[0025]
Suppose a radio frequency signal that is FSK modulated with an M value as an observation target signal. The M-value FSK modulated signal is generated by changing the carrier frequency to one of the following formulas (3) based on the transmission code.
[Equation 3]

[0026]
The carrier frequency can also be changed by switching and selecting the outputs of a plurality of oscillators having different oscillation frequencies, but sudden switching of the frequency causes the spectrum to expand. For this reason, CP (Continuous Phase) FSK that can maintain phase continuity is generally used.
[0027]
The phase of the carrier wave is expressed as an integral of past frequency shifts. Therefore, the phase trajectory of CPFSK can be expressed by a phase tree (phase diagram). The phase tree increases with time, that is, with observation time, but the phase of the carrier wave circulates in the range of 0 to 2π. Therefore, by making 2π modulo, the phase tree is degenerated and the predetermined set element is cyclically changed. The periodic steadiness of the radio frequency signal described above is a feature in which the periodicity appears by correlation calculation.
[0028]
FIG. 6 is a diagram illustrating a CSF response output from the FFT unit 33 when the signal processing unit 32 is not functioning. The observation target signal in FIG. 6 is quaternary FSK. As observed from FIG. 6, a peak corresponding to the multilevel number M of FSK appears in the graph in which the CSF of the M value FSK is plotted.
[0029]
FIG. 7 is a diagram illustrating a CSF response output from the FFT unit 33 when the signal processing unit 32 is not functioned with respect to the 8-level FSK signal. As can be seen from FIGS. 6 and 7, when the signal processing unit 32 is not functioned, the center of the CSF index rises as the modulation multi-level number increases, making it difficult to determine the multi-level number. That is, in order to determine the multi-value number from the CSF, the limit is about four values shown in FIG. 6, and as the modulation multi-value number increases, the degree of separation of the CSF sequence decreases, and the modulation multi-value number is estimated. Becomes difficult. This is because as the modulation multi-level number increases, the peak level corresponding to the multi-level number M decreases and the central disturbance component becomes conspicuous.
[0030]
Therefore, in the present embodiment, the signal sequence near the time axis origin of the CAF index is made zero by causing the signal processing unit 32 to function. The signal output from the periodic steadiness calculation unit 31 in FIG. 1 is a signal sequence represented by Expression (1). This series shows a shape as shown in FIG. As shown in FIG. 4, each series has a clear peak and can be distinguished from each other. Therefore, the series output from the periodic steadiness calculation unit 31 is represented by x (i), (i = 0, 1, ..., N-1). In FIG. 4, i corresponds to each numerical value on the horizontal axis (CAF index).
[0031]
For example, the signal processing unit 32 performs a process represented by the following equation (4) on x (i).
[Expression 4]

[0032]
That is, the signal processing unit 32 replaces the signal sequence in the range from the time axis origin (i = 0) to i <D with 0, and outputs the sequence in the range of i ≧ D to the FFT unit 33 as it is. I do.
[0033]
FIG. 8 is a diagram illustrating a CSF response output from the FFT unit 33 when the signal processing unit 32 is functioned, that is, when the signal processing unit 32 performs the above-described processing. The observation target signal in FIG. 8 is 4-level FSK, and the graph of FIG. 8 can be compared with FIG. As observed from FIG. 8, peaks separated better than those in FIG. 6 appear in the graph in which the CSF of the M-value FSK is plotted.
[0034]
FIG. 9 is a diagram illustrating a CSF response output from the FFT unit 33 when the signal processing unit 32 is caused to function with respect to an 8-level FSK signal. In FIG. 9, the bulge seen near the center of the CSF index graph in FIG. 7 disappears, and the peaks corresponding to the modulation multi-value number appear well separated. Therefore, by counting this peak, it is possible to accurately and easily estimate the modulation multilevel number.
[0035]
The waveforms as shown in FIG. 8 and FIG. 9 are observed when the reception state is good. However, actually, the signal is not necessarily in a good reception state, and the observation target signal is deteriorated due to noise or distortion of the radio propagation path.
[0036]
FIG. 10 is a diagram illustrating an example of a CSF response when affected by noise or the like. FIGS. 10A and 10B show examples in which the modulation multilevel number is four. From FIG. 10, it can be confirmed that the peak level corresponding to the modulation multi-level number varies, and further, the peak is broadened.
[0037]
Even in such a situation, in order to detect a peak corresponding to the modulation multi-level number, it is effective to perform a grouping process by a process on the machine side. By performing the grouping process, it is possible to improve the estimation accuracy of the modulation multilevel number M.
[0038]
FIG. 11 is a conceptual diagram for explaining grouping processing in the modulation multilevel number detection unit 34. As shown, the CSF signal sequence can be divided into a plurality of groups. By counting the number of these groups, the modulation multi-level number M of the radio frequency signal can be estimated.
[0039]
FIG. 12 is a conceptual diagram for more specifically explaining the grouping process by the modulation multilevel number detection unit 34. In FIG. 12, each CSF sequence is indicated by p [i]. Of these, the sequence with the largest value is denoted by Maxp [i]. Furthermore, a numerical value α having a value smaller than Maxp [i] is introduced, and a value Maxp [i] −α obtained by subtracting this from Maxp [i] is used as a determination reference level for grouping.
[0040]
Then, each series corresponds to a state of 0 or 1 with Maxp [i] −α as a boundary. This is indicated by q [i]. As shown in the figure, q [i] has a portion where 1 (series is equal to or greater than the reference value) continues while 0 (series is equal to or less than the reference value). By using this as a grouping index by software processing or the like, for example, it can be divided into four groups of group 1 to group 4 in FIG. Thus, it is determined that the modulation multi-level number M is 4.
[0041]
As described above, in this embodiment, the periodic stationarity of the BB signal obtained by down-converting the radio frequency signal is calculated by the periodic stationarity calculating unit 31, and a plurality of signal sequences of CAF index are generated. Then, the signal processing unit 32 replaces a sequence within a predetermined range from the time axis origin among these signal sequences with 0 and inputs the sequence to the FFT unit 33. The periodic stationary spectrum of the CSF index thus obtained is classified into two states under a predetermined determination reference level by the modulation multilevel number detection unit 34, and the modulation multilevel number of the radio frequency signal is detected. .
[0042]
In this way, by replacing the sequence near the origin of the time axis in the signal sequence of the CAF index with 0, the CSF index signal sequence graph is prevented from being raised, and the signal sequence of the CSF index is improved. Can be separated. The range of the CAF index to be replaced with 0 can be arbitrarily changed by the controller 40. For this reason, according to the present embodiment, it is possible to accurately and easily estimate the modulation multilevel number M for any radio frequency signal.
[0043]
(Second Embodiment)
FIG. 13 is a block diagram showing a second embodiment of the signal processing apparatus according to the present invention. In FIG. 13, parts common to FIG. 1 are given the same reference numerals, and only different parts will be described here. In FIG. 13, the BB signal output from the reception unit 20 is input to the frequency offset detection unit 61, the frequency offset correction unit 62, and the selector 63 of the signal analysis unit 60. The frequency offset detection unit 61 detects the frequency offset of the BB signal, and based on the result, the frequency offset correction unit 62 corrects the frequency offset of the BB signal.
[0044]
The selector 63 selects either a BB signal whose frequency offset is not corrected or a BB signal whose frequency offset is corrected, and inputs the selected signal to the detector 64 and the periodic stationary spectrum calculation unit 66. Which signal is selected is controlled by the control unit 68 of the signal analysis unit 60. The detector 64 detects the input BB signal and inputs the output to the statistic calculator 65. The statistic calculator 65 calculates a statistic such as an average and a variance related to the output signal of the detector 64. In the present embodiment, the statistic calculator 65 calculates the variance of the reception envelope of the observation target signal. The obtained statistic is input to the periodic stationary spectrum calculation unit 66.
[0045]
The periodic stationary spectrum calculation unit 66 includes the periodic stationarity calculation unit 31, the signal processing unit 32, and the FFT unit 33 of FIG. 1, and the periodic stationary spectrum of the input BB signal according to the procedure described in the first embodiment. Ask for. The CSF signal sequence output from the periodic stationary spectrum calculation unit 66 is passed to the modulation multilevel number detection unit 34, and the modulation multilevel number M of the radio frequency signal arriving at the antenna 10 is estimated.
[0046]
In the present embodiment, one of execution / stop of processing of the signal processing unit 32 (that is, on / off of the signal processing unit 32) in the periodic stationary spectrum calculation unit 66 is determined based on the reception envelope obtained by the statistic calculation unit 65. Make decisions based on variance. That is, the control unit 68 determines whether or not to replace a part of the CAF signal sequence with 0 based on the dispersion of the reception envelope of the received signal.
[0047]
The periodic steady spectrum calculation unit 66 compares the variance value of the reception envelope notified from the statistic calculation unit 65 with a preset threshold value. Then, the periodic steady spectrum calculation unit 66 functions so as to operate the signal processing unit 32 when the variance value is smaller than the threshold value, and not operate the signal processing unit 32 in other cases. The statistic calculation unit 65 compares the variance value and the threshold value, and gives a control signal for switching on / off of the signal processing unit 32 from the statistic calculation unit 65 to the periodic stationary spectrum calculation unit 66 according to the result. You may do it.
[0048]
As described above, by using the reception envelope statistics of the observation target signal, it is possible to detect a radio frequency signal modulated by FSK which is a constant envelope modulation method. By using this information, the modulation multi-level number can be detected more efficiently. That is, according to the present embodiment, in addition to the effects obtained by the first embodiment, the modulation multilevel number M can be estimated without requiring prior information. Furthermore, even in a situation where timing synchronization of radio frequency signals is not achieved, it is possible to improve the estimation accuracy of the modulation multilevel number.
[0049]
(More detailed explanation)
Next, the processing in the first and second embodiments will be described in more detail. FIG. 14 is a diagram illustrating another example of the time response of the periodic steadiness of the radio frequency signal. A periodic stationary spectrum is obtained by Fourier transforming the time response of the sequence of FIG. 14 into a frequency domain signal, and the number of modulation multi-levels can be estimated by counting the number of peaks of the periodic stationary spectrum.
[0050]
Periodic fluctuations are observed from the time response shown in FIG. This periodicity becomes a line spectrum component in the frequency domain. According to FIG. 14, periodic disturbance is observed in the region where the horizontal axis is 0 to 1. This disturbance of periodicity in the time domain also affects the frequency domain signal and causes deterioration in the periodic stationary spectrum. In the above embodiment, the influence of periodic disturbance is avoided by zeroing the vicinity of the origin of the horizontal axis.
[0051]
Although the horizontal axis in FIG. 14 is normalized by the signal transmission rate, since the signal transmission rate of the observation target signal is unknown when the apparatus is implemented, it corresponds to 0 to 1 as a range in which periodicity is disturbed. It is difficult to grasp exactly the area to do. In other words, it is difficult to accurately grasp the area for zero substitution.
[0052]
However, the object of the present invention is only to roughly remove the influence of the portion disturbing the periodicity, and therefore it is not necessary to strictly determine the region to be zeroed. That is, a sufficient effect can be obtained by zeroing the entire 1/4 from 0 (origin) of the time response or zeroing the entire 1/8 from 0 of the time response. That is, it is sufficient to avoid the influence of the time response in the vicinity of the time axis origin, which is a part that disturbs the periodicity, and therefore it is not necessary to strictly limit the area to be zeroed. As shown in FIG. 6, when the multi-value number is about four, the influence of periodic disturbance occurring near 0 in the time response is small. This is due to the fact that the level of the line spectrum corresponding to the multivalued number is larger than that of the CSF index near 0.
[0053]
FIG. 15 is a block diagram of a signal processing apparatus having a function of observing signal specifications. In FIG. 15, the receiving unit 20 receives the observation target signal and outputs the BB signal to the signal specification detecting unit 70 at the next stage. The signal specification detection unit 70 performs signal processing for detecting specifications related to modulation of the observation target signal based on an instruction from the controller 40. Each parameter detected by the signal specification detection unit 70 is passed to the display / interface unit 36 based on an instruction from the controller 40. The display / interface unit 36 visually displays each parameter detected by the signal specification detection unit 70. Further, the controller 40 comprehensively controls the receiving unit 20, the signal specification detecting unit 70, and the display / interface unit 36. Further, the controller 40 changes the operation of the signal processing device based on the instruction input from the display / interface unit 36.
[0054]
FIG. 16 is a block diagram illustrating a configuration example of the signal specification detection unit 70 of FIG. In FIG. 16, the BB signal output from the receiving unit 20 is input to the modulation multilevel number detection unit 71, the modulation format detection unit 72, the transmission rate detection unit 73, and the parameter detection unit 74. The processing function of the modulation multilevel number detection unit 71 is the same as described above. The modulation format detection unit 72 detects the modulation format of the observation target signal such as ASK, PSK, FSK, and outputs the result to the modulation multilevel number detection unit 71 and the display unit / interface unit 36. The transmission rate detection unit 73 detects the signal transmission rate of the observation target signal and outputs the result to the modulation multilevel number detection unit 71 and the display unit / interface unit 36. The various parameter detectors 74 detect other parameters related to the observation target signal. Control of each unit 75, 65, 31, 62, 76, 74, 77 is performed by the control unit 78 in an integrated manner.
[0055]
The above configuration is characterized in that both the signal output from the modulation format detector 72 and the signal output from the transmission rate detector 73 are input to the modulation multilevel number detector 71. By adopting such a configuration, it is possible to more efficiently implement the detection of the modulation multilevel number that is the object of the present invention.
[0056]
That is, by notifying the modulation multi-level number detection unit 71 of the transmission speed and modulation format of the observation target signal, it is possible to more accurately grasp the region that disturbs the periodicity as shown in FIG. Therefore, according to the above configuration, it is possible to more efficiently detect the multi-level number of radio frequency signals modulated by the FSK modulation method.
[0057]
FIG. 17 is a block diagram showing another configuration of a signal processing apparatus having a function of observing signal specifications. In FIG. 17, parts common to those in FIGS. 2, 3, and 16 are given the same reference numerals, and only different parts will be described here. When a signal that seems to be an observation target is observed in the signal band specifying unit 23 in FIG. 17, that is, when a signal that is equal to or higher than a preset power is observed in the power measuring unit 233, a band converting unit is selected to select the signal. The 24 passbands are converted, and the observation target signal is passed to the filter unit 26. The filter unit 26 roughly estimates the bandwidth of the observation target signal by the bandwidth estimation unit 261, and sets the band of the filter 262 according to the result to filter the target signal. The observation target signal that has passed through the filter 262 is input to the signal specification detection unit 70.
[0058]
The observation target signals input from the filter unit 26 to the signal specification detection unit 70 are respectively input to the peak detection unit 75, the statistic calculation unit 65, the periodic stationarity calculation unit 31, the symbol clock extraction unit 76, and the parameter detection unit 74. Entered. The peak detector 75 detects the peak of the observation target signal. The symbol clock extraction unit 76 extracts a symbol clock of the observation target signal.
[0059]
Each parameter detected by each unit 75, 65, 31, 76, 74 is given to the item classification processing unit 77. However, the signal series output from the periodic continuity calculation unit 31 is partially zeroed through the signal processing unit 32, and modulated multilevel data is acquired. This modulated multilevel data is supplied to the specification classification processing unit 77. Each of these parameters is stored in the reference data table 80 as a database. Further, by reading and referring to various parameters acquired in the past from the reference data table 80, it is possible to improve the estimation performance of the signal specifications.
[0060]
The present invention is not limited to the above embodiment.
For example, the periodic stationarity can be calculated by the following equation (5) obtained by modifying the equation (1).
[Equation 5]

[0061]
When the evaluation scale of equation (5) is required for other analysis signal processing, the same data can be shared with other analysis signal processing by using the periodic steadiness of equation (5). There are benefits.
[0062]
In the above embodiment, the radio frequency signal is down-converted and converted into a baseband signal. However, it may be converted into an intermediate frequency signal instead.
In the above embodiment, a part of the CAF signal sequence is replaced with 0. However, instead of this, it may be replaced with a constant value other than 0.
Furthermore, the present invention can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
[0063]
【The invention's effect】
As described in detail above, according to the present invention, it is possible to provide a signal processing device and a signal processing method capable of estimating the modulation multi-level number with high accuracy.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of a signal processing apparatus according to the present invention.
FIG. 2 is a diagram illustrating a configuration example of a receiving unit 20 in FIG.
3 is a diagram showing a configuration example of a signal band specifying unit 23 in FIG. 2;
4 is a diagram illustrating an example of a signal sequence output from a periodic steadiness calculating unit 31 in FIG. 1;
5 is a diagram illustrating an example of a CSF signal sequence output from an FFT unit 33 in FIG. 1;
FIG. 6 is a diagram illustrating a CSF response output from the FFT unit 33 when the signal processing unit 32 is not functioned with respect to a quaternary FSK signal.
FIG. 7 is a diagram showing a response of a CSF output from the FFT unit 33 when the signal processing unit 32 is not functioned with respect to an 8-level FSK signal.
FIG. 8 is a diagram illustrating a CSF response output from the FFT unit 33 when the signal processing unit 32 is caused to function with respect to a four-value FSK signal.
FIG. 9 is a diagram illustrating a CSF response output from the FFT unit 33 when the signal processing unit 32 is caused to function with respect to an 8-level FSK signal.
FIG. 10 is a diagram showing an example of a CSF response when affected by noise or the like.
11 is a conceptual diagram for explaining grouping processing in a modulation multi-level number detection unit 34. FIG.
FIG. 12 is a conceptual diagram for more specifically explaining grouping processing by a modulation multi-level number detection unit 34;
FIG. 13 is a block diagram showing a second embodiment of the signal processing apparatus according to the present invention.
FIG. 14 is a diagram showing another example of a time response of periodic steadiness of a radio frequency signal.
FIG. 15 is a block configuration diagram of a signal processing apparatus having a function of observing signal specifications.
16 is a block diagram showing a configuration example of a signal specification detection unit 70 in FIG.
FIG. 17 is a block diagram showing another configuration of a signal processing apparatus having a function of observing signal specifications.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Antenna, 20 ... Reception part, 21 ... Analog processing part, 22 ... ADC part, 23 ... Signal band specific part, 24 ... Band conversion part, 25 ... Bandwidth estimation part, 26 ... Filter part, 27 ... Control part, DESCRIPTION OF SYMBOLS 30 ... Signal analysis part, 31 ... Periodic continuity calculation part, 32 ... Signal processing part, 33 ... FFT part, 34 ... Modulation multi-value number detection part, 35 ... Display part, 36 ... Interface part, 40 ... Controller, 50 DESCRIPTION OF SYMBOLS ... Storage part, 60 ... Signal analysis part, 61 ... Frequency offset detection part, 62 ... Frequency offset correction part, 63 ... Selector, 64 ... Detector, 65 ... Statistics calculation part, 66 ... Periodical stationary spectrum calculation part, 68 ... Control unit, 70 ... signal specification detection unit, 71 ... modulation multi-value number detection unit, 72 ... modulation type detection unit, 73 ... transmission rate detection unit, 74 ... various parameter detection unit, 75 ... peak detection unit, 76 ... symbol Clock extractor, 7 ... specifications classification processing unit, 80 ... reference data table, 231 ... FFT unit, 232 ... filter bank forming part, 233 ... power measuring section, 234 ... comparator, 261 ... bandwidth estimation section, 262 ... filter

Claims (8)

Receiving means for receiving a multi-value modulated radio frequency signal and outputting a received signal;
Calculating means for calculating a periodic stationarity with respect to time of the received signal and outputting a plurality of signal sequences;
Replacing means for replacing a signal sequence appearing in a certain range with respect to a time axis among the plurality of signal sequences with a constant value;
Conversion means for converting a time response of a plurality of signal sequences including the signal sequence replaced with a constant value by the replacement means into a frequency domain and outputting a periodic stationary spectrum;
A signal processing apparatus comprising: detecting means for detecting a modulation multi-value number of the radio frequency signal from the periodic stationary spectrum. The signal processing apparatus according to claim 1, wherein the replacing unit replaces a signal sequence distributed near the origin of the time axis in the signal sequence output from the calculating unit with a constant value. The signal processing apparatus according to claim 1, wherein the constant value is zero. And statistical means for obtaining an envelope statistic of the received signal;
The signal processing apparatus according to claim 1, further comprising: a control unit that variably controls an appearance range of the signal series that is replaced with the constant value by the replacement unit based on the statistics. A calculation step of calculating a periodic stationarity with respect to time of a received signal based on a multi-frequency modulated radio frequency signal to generate a plurality of signal sequences;
A replacement step of replacing a signal sequence appearing in a certain range with respect to a time axis among the plurality of signal sequences with a constant value;
A conversion step of converting a time response of a plurality of signal sequences including the signal sequence replaced with a constant value in the replacement step into a frequency domain to generate a periodic stationary spectrum;
And a detection step of detecting a modulation multi-level number of the radio frequency signal from the periodic stationary spectrum. 6. The signal processing method according to claim 5, wherein the replacing step is a step of replacing a signal sequence distributed near the origin of the time axis among the signal sequences generated in the calculating step with a constant value. The signal processing method according to claim 5, wherein the constant value is zero. A statistical step of obtaining an envelope statistic of the received signal;
6. The signal processing method according to claim 5, further comprising a control step of variably controlling an appearance range of a signal sequence that is replaced with the constant value by the replacement unit based on the statistics.

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