JP4038420B2 - Radar data processing apparatus and distance / speed measuring method - Google Patents

Description

【００２３】
ビート信号（ＩとＱ）と送受信制御部２からの制御信号（ｘ）は、レーダ送受信装置１からレーダデータ処理装置１２へ入力される。
【００２４】
送受信制御部２からの制御信号により、レーダデータ処理装置１２のデータ処理制御部１３は、アップフェーズの期間では第３のスイッチ１４をＵ端子へ接続し、ダウンフェーズの期間では第３のスイッチ１４をＤ端子へ接続する。これにより、アップフェーズのビート信号はτ〜Ｔの時間において、τ毎にＡＤＣ１５ａによってサンプリングされ、メモリ１６ａに格納される。また、同様に、ダウンフェーズのビート信号はτ〜Ｔの時間において、τ毎にＡＤＣ１５ｂによってサンプリングされ、メモリ１６ｂに格納される。
【００２５】
格納の際には、図５に示されるように、各フェーズについて、送信信号Ｐ（１）に続くＭ個のサンプルを順に（Ｐ（１），Ｒ（１））、（Ｐ（１），Ｒ（２））、（Ｐ（１），Ｒ（３））、…、（Ｐ（１），Ｒ（Ｎ））として格納する。送信信号Ｐ（２）以降も同様に、（Ｐ（２），Ｒ（１））、（Ｐ（２），Ｒ（２））、（Ｐ（２），Ｒ（３））、…、（Ｐ（２），Ｒ（Ｎ））のように格納して、各フェーズ毎のデータマトリクスを生成する。このとき、Ｒ（ｋ） （ｋ＝１〜Ｎ）の行には、式（５）で示される範囲の相対距離Ｒｋにある目標の信号が含まれている。
【００２６】
【数２】

【００２７】
図６は、図２のレーダデータ処理装置におけるデータ処理手順であり、これらを用いて動作の説明をする。
【００２８】
まず、図１に示すレーダ送受信装置が上述のように動作し、さらに、図２のデータ処理制御部１３と、第３のスイッチ１４と、ＡＤＣ１５ａおよび１５ｂと、メモリ１６ａおよび１６ｂが上述のように動作し、メモリ１６ａおよび１６ｂ上に図５に示す各フェーズ毎のデータマトリクスが生成される。その後、図６の手順でデータ処理がすすむ。
【００２９】
図６に示す手順において、まず、ステップＳＴ１で、データ処理制御部１３が、自身に備わっているレンジゲート番号用カウンタ（内部変数）の値ｋをｋ＝１とする。
【００３０】
ステップＳＴ２では、データ処理制御部１３の制御により、レンジゲート１７ａがｋ番目の端子に接続することで、アップフェーズのビート信号を記録したメモリ１６ａから、｛Ｐ（１），Ｒ（ｋ）｝、｛Ｐ（２），Ｒ（ｋ）｝，…，｛Ｐ（Ｍ），Ｒ（ｋ）｝のデータ群を読み出し、ｋ番目のレンジにおけるビート信号データとして周波数抽出部１８ａに入力する。周波数抽出部１８ａはこのビート信号データについて、例えば、ＦＦＴにより周波数分析を行ない、目標に対応するビート周波数の抽出結果をデータ処理制御部１３、抽出結果判定部１０１および第２の距離・速度導出部１０２へ送る。
【００３１】
ステップＳＴ４では、ステップＳＴ２と同様に、データ処理制御部１３の制御により、レンジゲート１７ｂがｋ番目の端子に接続することで、ダウンフェーズのビート信号を記録したメモリ１６ｂから、｛Ｐ（１），Ｒ（ｋ）｝，｛Ｐ（２），Ｒ（ｋ）｝，…，｛Ｐ（Ｍ），Ｒ（ｋ）｝のデータ群を読み出し、ｋ番目のレンジにおけるビート信号データとして周波数抽出部１８ｂに入力する。周波数抽出部１８ｂはこのビート信号データについて例えばＦＦＴにより周波数分析を行ない、目標に対応するビート周波数の抽出結果をデータ処理制御部１３、抽出結果反値部１０１および第２の距離・速度導出部１０２へ送る。
【００３２】
ここで、アップフェーズにおける目標のビート周波数とダウンフェーズにおける目標のビート周波数の性質について述べる。アップフェーズにおける目標のビート周波数Ｕは式（３）で表され、距離に依存する右辺第１項と速度に依存する右辺第２項では正負の符号が異なる。これに対して、ダウンフェーズにおける目標のビート周波数Ｄは式（４）で表され、距離に依存する右辺第１項と速度に依存する右辺第２項では正負の符号が同じである。従って、目標の距離が遠く速度が正で大きな場合、すなわち、遠距離で高速に接近する目標の場合、目標のビート周波数の大きさ（絶対値）はアップフェーズの方が小さい。このため、アップフェーズにおける目標のビート周波数の方が、図７に示すようなパワーの減衰や図８に示すエリアシング現象が発生する確率が低い。これらを踏まえて、以降の処理が行なわれる。
【００３３】
ステップＳＴ１０１では、データ処理制御部１３の制御により、抽出結果判定部１０１が周波数抽出部１８ａの結果を入力し、アップフェーズにおける目標のビート周波数Ｕが抽出されているなら、ステップＳＴ１０２へ進み、抽出されていなければ、ステップＳＴ７に進む。
【００３４】
ステップＳＴ１０２では、データ処理制御部１３の制御により、抽出結果判定部１０１が周波数抽出部１８ｂの結果を入力し、ダウンフェーズにおける目標のビート周波数Ｄが抽出されているなら、ステップＳＴ１０３へ進み、抽出されていなければ、ステップＳＴ１０６に進む。
【００３５】
ステップＳＴ１０３では、抽出結果判定部１０１の制御により、第２の距離・速度導出部１０２がビート周波数ＵとＤから式（６）により距離Ｒを求める。
【００３６】
【数３】

【００３７】
続いてステップＳＴ１０４では、第２の距離・速度導出部１０２がステップＳＴ１０３で求めた距離Ｒが式（５）の関係を満足しているかを判定し、満足していれば、ステップＳＴ１０５へ進み、満足していなければ、ステップＳＴ１０６へ進む。
【００３８】
ステップＳＴ１０５では、第２の距離・速度導出部１０２がビート周波数ＵとＤから式（７）により速度Ｖを求め、後述するステップＳＴ７以降に進む。
【００３９】
【数４】

【００４０】
一方ステップＳＴ１０６では、ｋ番目のレンジゲートが対応する距離範囲の中心値である式（８）から目標距離Ｒｕを求め、この距離Ｒｕとアップフェーズの目標ビート周波数Ｕから式（９）により目標速度Ｖｕを求める。
【００４１】
【数５】

【００４２】
ステップＳＴ７では、データ処理制御部１３がカウンタｋの値をＮと比較し、等しくなければステップＳＴ８に進み、等しければステップＳＴ９に進む。
【００４３】
ステップＳＴ８では、データ処理制御部１３がカウンタｋの値をインクリメントして、ステップＳＴ２に進む。
【００４４】
また、ステップＳＴ９では、データ処理制御部１３が動作終了の判断を行ない、終了でなければステップＳＴ１進み、終了であれば終了する。例えば、使用者からの命令がデータ処理制御部１３へ入力された場合に動作終了となる。
【００４５】
以上のように、本実施の形態においては、遠距離から高速に接近する目標に対しては、アップフェーズのビート信号のみで目標を検知することにより、誤差の小さい距離と速度の測定を可能にすることができる。
【００４６】
実施の形態２．
以下、この発明の他の実施の形態について図を参照して説明する。図９は、本発明の他の実施の一形態であるレーダデータ処理装置の構成図である。
【００４７】
図９に示すように、本実施の形態においては、図２の抽出結果判定部１０１および第２の距離・速度導出部１０２の代わりに、第２の抽出結果判定部２０１および第３の距離・速度導出部２０２が設けられている。その他の構成要素は、上記の実施の形態１の図２で示したものと同等である。
【００４８】
また、図１０は図９のレーダデータ処理装置におけるデータ処理手順である。
【００４９】
まず、図１に示すレーダ送受信装置が上記実施の形態１と同様に動作し、さらに、図９のデータ処理制御部１３と、第３のスイッチ１４と、ＡＤＣ１５ａ、１５ｂと、メモリ１６ａ、１６ｂが上記と同様に動作し、メモリ１６上に図５に示す各フェーズ毎のデータマトリクスが生成される。その後、図１０の手順でデータ処理がすすむ。
【００５０】
ステップＳＴ１、ステップＳＴ２、ステップＳＴ４で、データ処理制御部１３と、レンジゲート１７ａ、１７ｂが上記と同様に動作して、メモリ１６ａ、１６ｂから読み出されたｋ番目のレンジにおけるビート信号データ群が周波数抽出部１８ａ、１８ｂへ入力され、目標に対応するビート周波数の抽出結果をデータ処理制御部１３と第２の抽出結果判定部２０１および第３の距離・速度導出部２０２へ送る。
【００５１】
ステップＳＴ１０１では、データ処理制御部１３の制御により、第２の抽出結果判定部２０１が周波数抽出部１８ａの結果を入力し、アップフェーズにおける目標のビート周波数Ｕが抽出されているなら、ステップＳＴ１０２へ進み、そうでなければ、ステップＳＴ７に進む。
【００５２】
ステップＳＴ１０２では、データ処理制御部１３の制御により、第２の抽出結果判定部２０１が周波数抽出部１８ｂの結果を入力し、ダウンフェーズにおける目標のビート周波数Ｄが抽出されているなら、ステップＳＴ２０１へ進み、そうでなければ、ステップＳＴ２０２に進む。
【００５３】
ステップＳＴ２０１では、ビート周波数ＵとＤの両方が抽出されている状態であるが、雑音など目標以外の不要な周波数成分が抽出される場合があり、全てのレンジゲートで、アップフェーズのビート周波数Ｕのみから式（８）と式（９）により距離と速度を求めるなら、本来は存在しない偽目標が発生する確率が増大する。そこで、あらかじめ設定したしきい値ｈよりも遠いレンジゲートにおいてのみ、式（８）と式（９）により距離と速度を求めることで、偽目標が発生する確率の増大が抑えられる。そこで、ステップＳＴ２０１では、現時点のレンジゲートｋの値をあらかじめ設定されたしきい値ｈと比較し、ｋ＞ｈであれば、ステップＳＴ１０３へ進み、ｋ≦ｈであれば、ステップＳＴ６へ進む。
【００５４】
ステップＳＴ１０３〜ステップＳＴ１０６では、第２の抽出結果判定部２０１と第３の距離・速度導出部２０２が、それぞれ、上記実施の形態１における抽出結果判定部１０１と第２の距離・速度導出部１０２と同様に動作して、目標の距離と速度を求める。
【００５５】
また、ステップＳＴ６では、第３の距離・速度導出部２０２が上記実施の形態１の距離・速度導出部１９と同様に動作して、目標の距離と速度を求める。
【００５６】
一方、ステップＳＴ２０２では、ステップＳＴ２０１と同じ理由で現時点のレンジゲートｋの値をあらかじめ設定されたしきい値ｈと比較し、ｋ＞ｈであればステップＳＴ１０６へ進み、ｋ≦ｈであれば、ステップＳＴ７へ進む。
【００５７】
ステップＳＴ７以降は、上記発明の実施の形態１と同様にデータ処理制御部１３が動作する。
【００５８】
以上のように、本実施の形態においては、あらかじめ設定されたしきい値ｈとレンジゲートｋの値とを比較して、しきい値以下のレンジゲート番号のときは、アップフェーズとダウンフェーズのビート周波数に基づいて目標の相対距離と相対速度とを求め、しきい値以下のレンジゲート番号のときは、アップフェーズのビート周波数に基づいて目標の相対距離と相対速度とを求めるようにしたので、遠距離から高速に接近する目標に対しては、アップフェーズのビート信号のみで目標を検知することにより、誤差の小さい距離と速度の測定を可能にすることができる。
【００５９】
実施の形態３．
以下、この発明の他の実施の形態について図を参照して説明する。図１１は、本発明の実施の一形態であるレーダデータ処理装置の構成図である。
【００６０】
図１１において、３０１は第３の抽出結果判定部、３０２は第４の距離・速度導出部、３０３は距離・速度予測部、３０４は周波数・ゲート番号予測部であり、その他の構成要素は、上記発明の実施の形態２の図３で示したものと同等である。
【００６１】
また、図１２および図１３は、図１１のレーダデータ処理装置におけるデータ処理手順である。
【００６２】
まず、図１に示すレーダ送受信装置が上記実施の形態１と同様に動作し、さらに、図１１のデータ処理制御部１３と、第３のスイッチ１４と、ＡＤＣ１５ａおよび１５ｂと、メモリ１６ａおよび１６ｂが上記実施の形態１と同様に動作し、メモリ１６上に図５に示す各フェーズ毎のデータマトリクスが生成される。その後、図１２および図１３の手順でデータ処理がすすむ。
【００６３】
まず、ステップＳＴ３０１で、データ処理制御部１３が、自身に備わっている既検知目標数用カウンタｑをｑ＝０とし、既検知目標の予測ビート周波数Ｆ（ｐ）と既検知目標の予測レンジゲート番号Ｋ（ｐ）をｐ＝１〜Ｐｍ（Ｐｍはあらかじめ設定された最大値）について初期化し、Ｆ（ｐ）＝０、Ｋ（ｐ）＝０とする。
【００６４】
続くステップＳＴ１、ステップＳＴ２、ステップＳＴ４では、データ処理制御部１３の制御により、レンジゲート１７ａ、１７ｂが上記実施の形態１と同様に動作して、メモリ１６ａ、１６ｂから読み出されたｋ番目のレンジにおけるビート信号データ群が周波数抽出部１８ａ、１８ｂへ入力され、目標に対応するビート周波数の抽出結果をデータ処理制御部１３へ送る。以降、ステップＳＴ１０１〜ステップＳＴ１０６、ステップＳＴ２０１、ステップＳＴ２０２、ステップＳＴ７〜ステップＳＴ９では、上記発明の実施の形態２と同様に動作する。
【００６５】
ただし、ステップＳＴ１０４では、ｋ＞ｈの関係を満足するレンジゲートｋにおいて、ビート周波数ＵとＤの両方が抽出された状態であり、これらＵとＤから式（６）によって求めた距離Ｒが式（５）の関係を満足しているか判定され、満足していれば、ステップＳＴ１０５へ進み、満足していなければ、ステップＳＴ３０９へ進む。
【００６６】
ステップＳＴ１０５では、第４の距離・速度導出部３０２が式（７）に基づいて速度Ｖを求める。続いてステップＳＴ３０２では、データ処理制御部１３が既検知目標数ｑの値を判定して、ｑ＝０であれば既検知目標がないとして、ステップＳＴ３０３へ進み、ｑ≠０であれば既検知目標があるとして、ステップＳＴ３０８へ進む。
【００６７】
ステップＳＴ３０３では、新規目標が検知されたとしてデータ処理制御部１３が既検知目標数ｑをインクリメントする。続くステップＳＴ３０４、ステップＳＴ３０５では、データ処理制御部１３が既検知目標数ｑが最大値Ｐｍを越えないように動作する。
【００６８】
続いてステップＳＴ３０６では、データ処理制御部１３の制御により、距離・速度予測部３０３が第４の距離・速度導出部３０２が求めた現観測時点の距離と速度から、次回観測時点の距離と速度を予測する。例えば、目標の運動モデルとして等速直線運動を仮定した場合、現時点の目標距離Ｒと目標速度ＶからＴｐ秒後の次回観測における予測距離Ｒｐと予測速度Ｖｐはそれぞれ式（１０）と式（１１）で求めることができる。
【００６９】
【数６】

【００７０】
続いてステップＳＴ３０７では、ステップＳＴ３０６で距離・速度予測部３０３により予測された距離と速度を入力した周波数・ゲート番号予測部３０４が、式（３）に基づいて次回観測における目標の予測ビート周波数Ｆ（ｐ）を式（１２）により求め、予測距離Ｒｐから予測レンジゲート番号Ｋ（ｐ）を式（１３）により求める。
【００７１】
【数７】

【００７２】
続くステップＳＴ７、ステップＳＴ８、ステップＳＴ９では上記実施の形態１と同様に、データ処理制御部１３が動作する。
【００７３】
また、ステップＳＴ３０８では、現在のレンジゲート番号ｋで抽出されたアップフェーズのビート周波数Ｕについて、既検知目標のうち式（１４）と式（１５）の両方の関係を同時に満足するＫ（ｐ）、Ｆ（ｐ）が存在するかを判定する。
【００７４】
【数８】

【００７５】
存在した場合、現在処理中の目標が既検知目標であるとして、ステップＳＴ３０６へ進み予測処理を行い、存在しない場合、新規検知目標であるとして、ステップＳＴ３０３へ進み既検知目標数ｑをインクリメントした後予測処理を行う。
【００７６】
一方、ステップＳＴ１０４で距離Ｒが式（５）の関係を満足しなかった状態のステップＳＴ３０９では、ステップＳＴ３０２と同様に、データ処理制御部１３が既検知目標数ｑの値を判定してｑ＝０であれば既検知目標がないとしてステップＳＴ１０６へ進み、ｑ≠０であれば既検知目標があるとしてステップＳＴ３１０へ進む。
【００７７】
ステップＳＴ１０６では、上記実施の形態１と同様に式（８）と式（９）により目標の距離と速度を求め、ステップＳＴ３０３へ進む。
【００７８】
ステップＳＴ３１０では、ステップＳＴ３０８と同様に、現在のレンジゲート番号ｋで抽出されたアップフェーズのビート周波数Ｕについて既検知目標のうち式（１４）と式（１５）を満足するＫ（ｐ）、Ｆ（ｐ）が存在するかを判定する。存在した場合、現在処理中の目標が既検知目標であるとして、ステップＳＴ３１１へ進み、存在しない場合、新規検知目標であるとして、ステップＳＴ１０６へ進み式（８）と式（９）により目標の距離と速度を求め、既検知目標数ｑをインクリメントした後予測処理を行う。
【００７９】
ステップＳＴ３１１では、現在のレンジゲート番号ｋで抽出されたアップフェーズのビート周波数Ｕと、予測値Ｋ（ｐ）、Ｆ（ｐ）から、式（１６）と式（１７）により目標の距離と速度求める。
【００８０】
【数９】

【００８１】
式（８）と式（９）によるＲｕとＶｕは ｃτ／２ を最小刻みとする離散値しかとりえなかったのに対し、式（１６）と式（１７）によるＲｓとＶｓはより小さな刻みを設定可能である。また、式（１６）と式（１７）は一種の追尾フィルタの形式になっていることから、距離と速度の測定精度を向上させることも可能である。
【００８２】
また、ステップＳＴ３１２では、アップフェーズのビート周波数Ｕが抽出されない状態やアップフェーズのビート周波数Ｕのみが抽出され、かつレンジゲート番号がｈより小さい状態であり、目標が検知できなかったとして、既検知目標の予測レンジゲート番号Ｋ（ｐ）のうち現在のレンジゲート番号ｋと同じものがないか判定し、同じ番号があった場合、ステップＳＴ３１３に進み、同じ番号がない場合、ステップＳＴ７へ進む。
【００８３】
ステップＳＴ３１３では、ステップＳＴ３１２でレンジゲート番号が一致した既検知目標を見失ったとして、該当するＫ（ｐ）とＦ（ｐ）を初期化する。
【００８４】
続いて、ステップＳＴ３１４では、既検知目標数ｑをデクリメントする。
【００８５】
続くステップＳＴ３１５、ステップＳＴ３１６では、データ処理制御部１３が既検知目標数ｑの値が０未満にならないように動作する。
【００８６】
以上のように、本実施の形態においては、上述の実施の形態１および２の効果に加えて、さらに、現観測時点で得られた目標の相対距離および相対速度から、次回観測時点の目標のビート周波数とレンジゲート番号とを予測し、次回観測において該予測値と相関がある観測値については、予測値と観測値とから、目標の相対距離と相対速度とを求めるようにしたので、遠距離から高速に接近する目標に対しては、アップフェーズのビート信号のみで目標を検知することにより、誤差の小さい距離と速度の測定を可能にすることができる。
【００８７】
【発明の効果】
この発明は、周波数が徐々に増加するアップフェーズと徐々に減少するダウンフェーズとを有する周波数変調された変調波信号と、所定の測定期間間隔で上記変調波信号に基づいて間欠的に発生された送信信号の目標での反射波であり上記目標の相対速度に応じたドップラー周波数成分だけ上記送信信号からシフトした受信信号との周波数差を示すビート信号を生成するビート信号生成ステップと、生成された上記ビート信号を、上記各送信信号の送信後の所定の期間において、それぞれ連続的に所定の距離範囲に対応させて所定時間間隔ごとにサンプリングするサンプリングステップと、サンプリングされた上記ビート信号と上記送信信号とからなる各フェーズ毎のデータマトリクスを生成するデータマトリクス生成ステップと、各送信信号に対して所定の同一番目にサンプリングした上記ビート信号のデータ群を、サンプリング順を示す番号を指定することにより、上記データマトリクスから読み出すデータ群読出ステップと、読み出されたデータ群を周波数分析して、ビート周波数を求めるビート周波数抽出ステップと、上記番号と上記時間間隔とに基づいて、目標の距離を求めるとともに、求められた上記目標の距離と上記アップフェーズにおいて抽出された上記ビート周波数とレーダで用いる周波数掃引幅とレーダで用いる周波数掃引時間とレーダで用いる波長とに基づいて、目標の相対速度を求める距離・速度測定ステップとを備えた距離・速度測定方法であるので、遠距離から高速に接近する目標に対しては、アップフェーズのビート信号のみで目標を検知することにより、距離と速度の測定を精度高く行うことができる。
【図面の簡単な説明】
【図１】 ＦＭＩＣＷレーダの送受信装置の構成を示すブロック図である。
【図２】 本発明の実施の形態１によるレーダデータ処理装置の構成を示すブロック図である。
【図３】 ＦＭＩＣＷレーダにおける各信号の時間に対する周波数を示した説明図である。
【図４】 図１の構成における第１のスイッチおよび第２のスイッチにおける接続端子を時間に対して示した説明図である。
【図５】 図２のメモリにおけるアップフェーズおよびダウンフェーズのビート信号をサンプリングして、生成するデータマトリクスを示した説明図である。
【図６】 本発明の実施の形態１によるレーダデータ処理装置のデータ処理手順を示した流れ図である。
【図７】 ＦＭＩＣＷレーダにおいて、ＡＤＣ帯域外になった場合のパワーの減衰を示した説明図である。
【図８】 ＦＭＩＣＷレーダにおいて、ＦＦＴ帯域以上になった場合のエリアシング現象を示した説明図である。
【図９】 本発明の実施の形態２によるレーダデータ処理装置の構成を示すブロック図である。
【図１０】 本発明の実施の形態２によるレーダデータ処理装置のデータ処理手順を示した流れ図である。
【図１１】 本発明の実施の形態２によるレーダデータ処理装置の構成を示すブロック図である。
【図１２】 本発明の実施の形態２によるレーダデータ処理装置のデータ処理手順を示した流れ図である。
【図１３】 本発明の実施の形態２によるレーダデータ処理装置のデータ処理手順を示した流れ図である。
【符号の説明】
１ レーダ送受信装置、２ 送受信制御部、３ 変調波形発生部、４ ＶＣＯ、５ 第１のスイッチ、６ 第２のスイッチ、７ アンテナ、８ 目標、９ａ，９ｂ 分配回路、１０ 移相回路、１１ａ，１１ｂ ミクサ、１２ レーダデータ処理装置、１３ データ処理制御部、１４ 第３のスイッチ、１５ａ，１５ｂＡＤＣ、１６ａ，１６ｂ メモリ、１７ａ，１７ｂ レンジゲート、１８ａ，１８ｂ 周波数抽出部、１０１ 抽出結果判定部、１０２ 第２の距離・速度導出部、２０１ 第２の抽出結果判定部、２０２ 第３の距離・速度導出部、３０１ 第３の抽出結果判定部、３０２ 第４の距離・速度導出部、３０３ 距離・速度予測部、３０４ 周波数・ゲート番号予測部。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radar data processing apparatus and a distance / speed measuring method, and more particularly, radar data mounted on a moving body such as a vehicle, for detecting a target object and measuring the relative distance and relative speed. The present invention relates to a processing apparatus and a distance / speed measuring method.
[0002]
[Prior art]
A radar mounted on a vehicle or the like has a target distance in the range of several meters to several hundred meters, and the antenna becomes smaller if one antenna is used for both transmission and reception. It is desirable for mounting on a moving body. In order to satisfy such a demand, FMICW (Frequency Modulated Integrated Continuous Wave) radar is known as a conventional radar (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
JP 2000-275333 A
[0004]
In the conventional apparatus, in the relative distance / velocity measurement by FMICW, a plurality of distance bin data is calculated and added, the frequency spectrum is obtained for the calculated distance bin data, and the up phase and the down phase are obtained respectively. Find the frequency of the spectrum detected as the target for the frequency spectrum, search for combinations where the relative distance is within the range of the specified distance bin by combining the frequencies of the up-phase and down-phase spectra, and calculate the relative The distance is output, and the target relative speed is obtained from the corresponding combination and output.
[0005]
Here, a modulation interval in which the frequency increases with the passage of time is referred to as an up phase, and a modulation interval in which the frequency decreases with the passage of time is referred to as a down phase.
[0006]
[Problems to be solved by the invention]
When the conventional FMICW radar configured as described above is mounted on a vehicle or the like, it is desirable that the size is small, so that the band of ADC (Analog to Digital Converter) is limited in order not to make the configuration as complicated as possible. In order to reduce the arithmetic circuit, the number of FFT (Fast Fourier Transform) points is limited. At this time, in the case of a target approaching at high speed from a long distance, the absolute value of the target beat frequency in the down phase is large, and when it is outside the ADC band, the spectral power of the beat signal is attenuated from the frequency characteristics of the ADC. Therefore, there is a problem that the target beat frequency cannot be extracted in the down phase and the target cannot be detected.
[0007]
Similarly, when the absolute value of the target beat frequency in the down phase is large and exceeds the FFT band, the correct frequency of the target in the down phase can be obtained by turning the frequency back by the so-called aliasing phenomenon. However, there is a problem that it becomes an error factor of the target distance and speed.
[0008]
The present invention has been made to solve such a problem. For a target approaching at high speed from a long distance, the distance and speed are measured by detecting the target only with an up-phase beat signal. It is an object of the present invention to obtain a radar data processing apparatus and a distance / speed measuring method which can be performed with high accuracy.
[0009]
[Means for Solving the Problems]
The present invention is a frequency-modulated modulated wave signal having an up phase in which the frequency gradually increases and a down phase in which the frequency gradually decreases, and is intermittently generated based on the modulated wave signal at a predetermined measurement period interval. A beat signal generation step for generating a beat signal that is a reflected wave at the target of the transmission signal and that indicates a frequency difference from the reception signal shifted from the transmission signal by a Doppler frequency component corresponding to the relative speed of the target; The beat signal is continuously associated with a predetermined distance range in a predetermined period after transmission of each transmission signal. Every predetermined time interval A sampling step for sampling, a data matrix generation step for generating a data matrix for each phase composed of the sampled beat signal and the transmission signal, and the beat signal sampled at a predetermined same number for each transmission signal By specifying a number indicating the sampling order of the data group, a data group reading step for reading from the data matrix, a beat frequency extracting step for analyzing the frequency of the read data group and obtaining a beat frequency, Based on the number and the time interval, the target distance is obtained, and the obtained target distance and The beat frequency extracted in the up phase Frequency sweep width used by radar, frequency sweep time used by radar, wavelength used by radar Based on goal Relative speed of A distance / speed measuring method including a distance / speed measuring step to be obtained.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a basic configuration of a general FMICW radar transmission / reception device described in Patent Document 1 described above. As the name suggests, the FMICW radar intermittently uses a continuous wave subjected to frequency modulation. The radar transmitter / receiver 1 generates a transmission signal and radiates it from the antenna 7 into the air. The transmission signal radiated into the air is irradiated onto the target 8 and a part thereof is reflected. The reflected wave is received by the antenna 7 and processed by the radar transmitter / receiver 1 to obtain the relative distance and speed of the target 8. In the radar transmission / reception apparatus 1, as shown in FIG. 1, a transmission / reception control unit 2 that controls a modulation waveform generation unit 3 and first and second switches 5 and 6, which will be described later, and a control of the transmission / reception control unit 2. A modulation waveform generator 3 that generates a modulation waveform composed of an up phase and a down phase, a VCO (Voltage Controlled Oscillator) 4 that generates a VCO signal from the modulation waveform generated by the modulation waveform generator 3, and control of the transmission / reception controller 2 The first switch 5 and the second switch 6 that switch the terminal t and the terminal r in synchronization with each other, and the VCO signal input from the VCO 4 while the switches 5 and 6 are connected to the t terminal. The antenna 7 that receives the reflected wave that is radiated into the air and is reflected back to the target 8 and the switches 5 and 6 are connected to the r terminal. While the reception signal received by the antenna 7 is input, the distribution signal 9a is divided into two and input to the mixer 11a and the mixer 11b, and the switches 5 and 6 are connected to the r terminal. While the VCO signal from the VCO 4 is input as a local signal, the VCO signal is divided into two, and the phase of the signal input from the distribution circuit 9b and the distribution circuit 9b input to the phase circuit 10 and the mixer 11a is set to a predetermined value. The phase shift circuit 10 that shifts the value and the input received signal and the local signal are mixed so that the real part (I) and the imaginary part of the complex signal of the beat signal in which the frequency difference between the received signal and the local signal appears as a frequency. There are provided mixers 11a and 11b for generating the part (Q), respectively.
[0011]
FIG. 2 is a configuration diagram of the radar data processing apparatus according to the embodiment of the present invention. As shown in FIG. 2, a signal from the transmission / reception control unit 2 is input into the radar data processing device 12, and a data processing control unit 13 for controlling the overall operation and beat signals (I and Q) are provided. A third switch 14 that is input from the mixers 11a and 11b and connected to the U terminal during the up phase and connected to the D terminal during the down phase, and a beat that is input via the third switch 14 ADCs 15a and 15b for sampling signals at predetermined time intervals in a predetermined period, memories 16a and 16b for storing sampled beat signals, N terminals, and k-th data under the control of the data processing control unit 13 Range gates 17a and 17b connected to the terminals of the first and kth ranges input via the range gates 17a and 17b The beat signal data is input, and the frequency extraction units 18a and 18b that perform frequency analysis of the beat signal data, and the extraction result determination unit 101 that determines whether the target beat frequency in the down phase is extracted based on the extraction result. When the target beat frequency in the down phase has been extracted by the control of the extraction result determination unit 101, the target distance and speed are obtained from the beat frequency in the up phase and the down phase, while in the down phase When the target beat frequency is not extracted, a second distance / speed deriving unit 102 for obtaining the target distance and speed from the beat frequency of the up phase is provided.
[0012]
FIG. 3 shows the frequency with respect to time of each signal in the FMICW radar. In FIG. 3, 20a is an up-phase VCO signal, 20b is a down-phase VCO signal, 21a is an up-phase transmission signal, and 21b. Is a down phase transmission signal, 22a is an up phase local signal, 22b is a down phase local signal, 23a is an up phase reception signal, 23b is a down phase reception signal, 24a is an up phase beat signal, and 24b is down This is the beat signal of the phase.
[0013]
FIG. 4 shows connection terminals with respect to time in the first switch 5 and the second switch 6 of FIG.
[0014]
FIG. 5 is a data matrix generated by sampling up-phase and down-phase beat signals in the memories 16a and 16b of FIG. Each transmission signal P (i) (i = 1 to M) constitutes a column of the data matrix, and each beat signal R (k) (k = 1 to N) constitutes a row.
[0015]
FIG. 6 is a flowchart showing a data processing procedure in FIG.
[0016]
The operation of the FMICW radar in the present embodiment will be described using these figures. The FMICW radar intermittently uses a continuous wave subjected to frequency modulation. In FIG. 1, the modulation waveform composed of the up phase and the down phase generated by the modulation waveform generation unit 3 is input to the VCO 4 by the control of the transmission / reception control unit 2 in the radar transmission / reception apparatus 1, and the VCO signal 20 shown in FIG. And is input to the first switch 5. The first switch 5 and the second switch 6 are controlled by the transmission / reception control unit 2, and as shown in FIG. 4, to the t terminal for a preset time τ and to the r terminal for the other time T−τ. The operation of connecting in synchronization with each other is repeated.
[0017]
First, in the period of the up phase, the VCO signal 20a connected to the t terminal for the time τ becomes the transmission signal 21a, which is input to the antenna 7 via the first switch 5 and the second switch 6, and from the antenna 7 From the air. The transmission signal 21a radiated into the air is irradiated to the target 8 which exists at a certain relative distance R and is moving at a certain relative velocity V, and a part of it is reflected.
[0018]
The reflected wave is shifted by the Doppler frequency Fv corresponding to the relative velocity V, and is received by the antenna 7 at a time delayed by kτ = 2R / c (c is the velocity of the radio wave) from the transmission signal 21a. The signal 23a is input to the distribution circuit 9a via the second switch 6 connected to the r terminal for the time T-τ. The distribution circuit 9a divides the input signal into two and inputs them to the mixer 11a and the mixer 11b, respectively. On the other hand, the VCO signal 20a via the first switch 5 connected to the r terminal for the time T-τ is input to the distribution circuit 9b as the local signal 22a. The distribution circuit 9b divides the input signal into two and inputs it to the mixer 11a and the phase shift circuit 10. The phase shift circuit 10 shifts the phase of the input signal by π / 2 radians and outputs it to the mixer 11b.
[0019]
The received signal 23a and the local signal 22a input to each mixer 11a, 11b are mixed in a period of kτ to (k + 1) τ within the time T−τ, and the beat in which the frequency difference between the received signal 23a and the local signal 22a appears as a frequency. It becomes a signal 24a. At this time, since the beat signal 24a from the mixer 11a corresponds to the real part (I) of the complex signal and the beat signal 24a from the mixer 11b corresponds to the imaginary part (Q) of the complex signal, the beat signal 24a is obtained as a complex signal.
[0020]
In the down phase period, the beat signal 24b is obtained in the same manner as in the up phase period.
[0021]
At this time, the beat signal 24a Sup (t) in the up phase is expressed by the following equation (1), and the beat signal 24b Sdn (t) in the down phase is expressed by the following equation (2).
[0022]
[Expression 1]

[0023]
The beat signals (I and Q) and the control signal (x) from the transmission / reception control unit 2 are input from the radar transmission / reception device 1 to the radar data processing device 12.
[0024]
Based on the control signal from the transmission / reception control unit 2, the data processing control unit 13 of the radar data processing device 12 connects the third switch 14 to the U terminal during the up-phase period, and the third switch 14 during the down-phase period. To the D terminal. As a result, the beat signal in the up phase is sampled by the ADC 15a for each τ and stored in the memory 16a during the time period τ to T. Similarly, the beat signal in the down phase is sampled by the ADC 15b for each τ in the time τ to T and stored in the memory 16b.
[0025]
At the time of storage, as shown in FIG. 5, M samples following the transmission signal P (1) are sequentially (P (1), R (1)), (P (1), R (2)), (P (1), R (3)), ..., (P (1), R (N)). Similarly, after the transmission signal P (2), (P (2), R (1)), (P (2), R (2)), (P (2), R (3)),. P (2), R (N)) are stored, and a data matrix for each phase is generated. At this time, the row of R (k) (k = 1 to N) includes the target signal at the relative distance Rk in the range represented by Expression (5).
[0026]
[Expression 2]

[0027]
FIG. 6 shows a data processing procedure in the radar data processing apparatus of FIG. 2, and the operation will be described using these procedures.
[0028]
First, the radar transmission / reception apparatus shown in FIG. 1 operates as described above. Further, the data processing control unit 13, the third switch 14, ADCs 15a and 15b, and memories 16a and 16b shown in FIG. In operation, a data matrix for each phase shown in FIG. 5 is generated on the memories 16a and 16b. Thereafter, data processing proceeds according to the procedure of FIG.
[0029]
In the procedure shown in FIG. 6, first, in step ST1, the data processing control unit 13 sets the value k of the range gate number counter (internal variable) provided therein to k = 1.
[0030]
In step ST2, the range gate 17a is connected to the k-th terminal under the control of the data processing control unit 13, so that {P (1), R (k)} from the memory 16a in which the up-phase beat signal is recorded. , {P (2), R (k)},..., {P (M), R (k)} are read out and input to the frequency extraction unit 18a as beat signal data in the kth range. The frequency extraction unit 18a performs frequency analysis on the beat signal data by, for example, FFT, and obtains the extraction result of the beat frequency corresponding to the target as the data processing control unit 13, the extraction result determination unit 101, and the second distance / speed derivation unit. Send to 102.
[0031]
In step ST4, similarly to step ST2, the range gate 17b is connected to the k-th terminal under the control of the data processing control unit 13, so that {P (1) , R (k)}, {P (2), R (k)},..., {P (M), R (k)} are read out, and the frequency extraction unit is used as beat signal data in the kth range. Input to 18b. The frequency extraction unit 18b performs frequency analysis on the beat signal data by, for example, FFT, and extracts the beat frequency extraction result corresponding to the target as the data processing control unit 13, the extraction result inverse value unit 101, and the second distance / speed deriving unit 102. Send to.
[0032]
Here, the characteristics of the target beat frequency in the up phase and the target beat frequency in the down phase will be described. The target beat frequency U in the up phase is expressed by Equation (3), and the positive and negative signs are different between the first term on the right side depending on the distance and the second term on the right side depending on the speed. On the other hand, the target beat frequency D in the down phase is expressed by Equation (4), and the sign of the positive and negative is the same in the first term on the right side depending on the distance and the second term on the right side depending on the speed. Therefore, when the target distance is far and the speed is positive and large, that is, when the target is approaching at high speed at a long distance, the magnitude (absolute value) of the target beat frequency is smaller in the up phase. For this reason, the target beat frequency in the up phase has a lower probability of power attenuation as shown in FIG. 7 and aliasing phenomenon shown in FIG. Based on these, the following processing is performed.
[0033]
In step ST101, under the control of the data processing control unit 13, if the extraction result determination unit 101 inputs the result of the frequency extraction unit 18a and the target beat frequency U in the up phase has been extracted, the process proceeds to step ST102 and extracted. If not, the process proceeds to step ST7.
[0034]
In step ST102, if the extraction result determination unit 101 inputs the result of the frequency extraction unit 18b under the control of the data processing control unit 13 and the target beat frequency D in the down phase has been extracted, the process proceeds to step ST103 for extraction. If not, the process proceeds to step ST106.
[0035]
In step ST103, under the control of the extraction result determination unit 101, the second distance / speed deriving unit 102 obtains the distance R from the beat frequencies U and D according to the equation (6).
[0036]
[Equation 3]

[0037]
Subsequently, in step ST104, the second distance / speed deriving unit 102 determines whether the distance R obtained in step ST103 satisfies the relationship of the expression (5). If satisfied, the process proceeds to step ST105. If not satisfied, the process proceeds to step ST106.
[0038]
In step ST105, the second distance / velocity deriving unit 102 obtains the velocity V from the beat frequencies U and D by the equation (7), and proceeds to step ST7 and later.
[0039]
[Expression 4]

[0040]
On the other hand, in step ST106, the target distance Ru is obtained from Expression (8) which is the center value of the distance range to which the kth range gate corresponds, and the target speed is calculated from Expression (9) from this distance Ru and the up-phase target beat frequency U. Obtain Vu.
[0041]
[Equation 5]

[0042]
In step ST7, the data processing control unit 13 compares the value of the counter k with N, and if not equal, proceeds to step ST8, and if equal, proceeds to step ST9.
[0043]
In step ST8, the data processing control unit 13 increments the value of the counter k, and proceeds to step ST2.
[0044]
In step ST9, the data processing control unit 13 determines the end of the operation. If not, the process proceeds to step ST1, and if completed, the process ends. For example, the operation ends when a command from the user is input to the data processing control unit 13.
[0045]
As described above, in the present embodiment, for a target approaching at high speed from a long distance, it is possible to measure a distance and speed with a small error by detecting the target only with an up-phase beat signal. can do.
[0046]
Embodiment 2. FIG.
Hereinafter, another embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a configuration diagram of a radar data processing apparatus according to another embodiment of the present invention.
[0047]
As shown in FIG. 9, in the present embodiment, instead of the extraction result determination unit 101 and the second distance / speed deriving unit 102 in FIG. 2, the second extraction result determination unit 201 and the third distance / A speed deriving unit 202 is provided. Other components are the same as those shown in FIG. 2 of the first embodiment.
[0048]
FIG. 10 shows a data processing procedure in the radar data processing apparatus of FIG.
[0049]
First, the radar transmission / reception apparatus shown in FIG. 1 operates in the same manner as in the first embodiment. Further, the data processing control unit 13, the third switch 14, ADCs 15a and 15b, and memories 16a and 16b shown in FIG. The operation is the same as described above, and a data matrix for each phase shown in FIG. Thereafter, data processing proceeds according to the procedure of FIG.
[0050]
In step ST1, step ST2, and step ST4, the data processing control unit 13 and the range gates 17a and 17b operate in the same manner as described above, and the beat signal data group in the kth range read from the memories 16a and 16b is obtained. Input to the frequency extraction units 18 a and 18 b and send the extraction result of the beat frequency corresponding to the target to the data processing control unit 13, the second extraction result determination unit 201, and the third distance / speed derivation unit 202.
[0051]
In step ST101, if the second extraction result determination unit 201 inputs the result of the frequency extraction unit 18a under the control of the data processing control unit 13, and the target beat frequency U in the up phase is extracted, the process proceeds to step ST102. Otherwise, go to step ST7.
[0052]
In step ST102, if the second extraction result determination unit 201 inputs the result of the frequency extraction unit 18b and the target beat frequency D in the down phase is extracted under the control of the data processing control unit 13, the process proceeds to step ST201. If not, the process proceeds to step ST202.
[0053]
In step ST201, both beat frequencies U and D are extracted. However, unnecessary frequency components other than the target such as noise may be extracted, and the up-phase beat frequency U may be extracted in all range gates. If the distance and speed are obtained from the equation (8) and the equation (9) only from the above, the probability that a false target that does not exist originally will increase. Therefore, the increase in the probability of occurrence of a false target can be suppressed by calculating the distance and speed only by the range gate farther than the preset threshold value h using the equations (8) and (9). In step ST201, the current value of the range gate k is compared with a preset threshold value h. If k> h, the process proceeds to step ST103, and if k ≦ h, the process proceeds to step ST6.
[0054]
In step ST103 to step ST106, the second extraction result determination unit 201 and the third distance / speed deriving unit 202 are respectively connected to the extraction result determination unit 101 and the second distance / speed deriving unit 102 in the first embodiment. Operate in the same manner as above to find the target distance and speed.
[0055]
In step ST6, the third distance / speed deriving unit 202 operates in the same manner as the distance / speed deriving unit 19 in the first embodiment to obtain the target distance and speed.
[0056]
On the other hand, in step ST202, the current value of the range gate k is compared with a preset threshold value h for the same reason as in step ST201. If k> h, the process proceeds to step ST106, and if k ≦ h, Proceed to step ST7.
[0057]
After step ST7, the data processing control unit 13 operates as in the first embodiment of the present invention.
[0058]
As described above, in the present embodiment, the threshold value h set in advance and the value of the range gate k are compared, and when the range gate number is less than or equal to the threshold value, the up phase and the down phase The target relative distance and relative speed are calculated based on the beat frequency, and when the range gate number is less than or equal to the threshold, the target relative distance and relative speed are calculated based on the up-phase beat frequency. For a target approaching at high speed from a long distance, the distance and speed can be measured with a small error by detecting the target only with the up-phase beat signal.
[0059]
Embodiment 3 FIG.
Hereinafter, another embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a configuration diagram of a radar data processing apparatus according to an embodiment of the present invention.
[0060]
In FIG. 11, 301 is a third extraction result determination unit, 302 is a fourth distance / speed deriving unit, 303 is a distance / speed prediction unit, 304 is a frequency / gate number prediction unit, and other components are: This is the same as that shown in FIG. 3 of the second embodiment of the present invention.
[0061]
12 and 13 show data processing procedures in the radar data processing apparatus of FIG.
[0062]
First, the radar transmission / reception apparatus shown in FIG. 1 operates in the same manner as in the first embodiment. Further, the data processing control unit 13, the third switch 14, ADCs 15a and 15b, and memories 16a and 16b shown in FIG. The operation is the same as in the first embodiment, and a data matrix for each phase shown in FIG. Thereafter, the data processing proceeds according to the procedure shown in FIGS.
[0063]
First, in step ST301, the data processing control unit 13 sets a counter q for the number of already detected targets included therein to q = 0, the predicted beat frequency F (p) of the already detected target, and the predicted range gate of the already detected target. The number K (p) is initialized for p = 1 to Pm (Pm is a preset maximum value), and F (p) = 0 and K (p) = 0.
[0064]
In subsequent steps ST1, ST2, and ST4, the range gates 17a and 17b operate in the same manner as in the first embodiment under the control of the data processing control unit 13, and the kth read out from the memories 16a and 16b. The beat signal data group in the range is input to the frequency extraction units 18 a and 18 b, and the extraction result of the beat frequency corresponding to the target is sent to the data processing control unit 13. Thereafter, in steps ST101 to ST106, step ST201, step ST202, and steps ST7 to ST9, the operation is the same as in the second embodiment of the present invention.
[0065]
However, in step ST104, both the beat frequencies U and D are extracted in the range gate k satisfying the relationship of k> h, and the distance R obtained from these U and D by the equation (6) is the equation. It is determined whether the relationship (5) is satisfied. If satisfied, the process proceeds to step ST105, and if not satisfied, the process proceeds to step ST309.
[0066]
In step ST105, the fourth distance / speed deriving unit 302 obtains the speed V based on the equation (7). Subsequently, in step ST302, the data processing control unit 13 determines the value of the already detected target number q. If q = 0, it is determined that there is no already detected target, and the process proceeds to step ST303. If there is a target, the process proceeds to step ST308.
[0067]
In step ST303, assuming that a new target is detected, the data processing control unit 13 increments the detected target number q. In subsequent steps ST304 and ST305, the data processing control unit 13 operates so that the detected target number q does not exceed the maximum value Pm.
[0068]
Subsequently, in step ST306, under the control of the data processing control unit 13, the distance and speed at the next observation time are calculated from the distance and speed at the current observation time obtained by the fourth distance / speed deriving unit 302 by the distance / speed prediction unit 303. Predict. For example, when constant velocity linear motion is assumed as the target motion model, the predicted distance Rp and the predicted speed Vp in the next observation Tp seconds after the current target distance R and target speed V are expressed by the equations (10) and (11), respectively. ).
[0069]
[Formula 6]

[0070]
Subsequently, in step ST307, the frequency / gate number prediction unit 304 that has input the distance and speed predicted by the distance / velocity prediction unit 303 in step ST306 performs the target predicted beat frequency F in the next observation based on the equation (3). (P) is obtained from equation (12), and the prediction range gate number K (p) is obtained from equation (13) from the prediction distance Rp.
[0071]
[Expression 7]

[0072]
In subsequent step ST7, step ST8, and step ST9, the data processing control unit 13 operates as in the first embodiment.
[0073]
Further, in step ST308, for the up-phase beat frequency U extracted with the current range gate number k, K (p) that satisfies both the expressions (14) and (15) among the detected targets at the same time. , F (p) exists.
[0074]
[Equation 8]

[0075]
If it exists, it is determined that the target currently being processed is a detected target, and the process proceeds to step ST306. If it does not exist, it is determined that the target is a new detected target, and the process proceeds to step ST303 and the detected target number q is incremented. Perform prediction processing.
[0076]
On the other hand, in step ST309 in which the distance R does not satisfy the relationship of Expression (5) in step ST104, as in step ST302, the data processing control unit 13 determines the value of the detected target number q, and q = If 0, it is determined that there is no detected target, and the process proceeds to step ST106. If q ≠ 0, it is determined that there is a detected target, and the process proceeds to step ST310.
[0077]
In step ST106, the target distance and speed are obtained by equations (8) and (9) as in the first embodiment, and the process proceeds to step ST303.
[0078]
In Step ST310, as in Step ST308, K (p), F satisfying Expressions (14) and (15) among the detected targets for the up-phase beat frequency U extracted with the current range gate number k. It is determined whether (p) exists. If it exists, the process proceeds to step ST311 assuming that the target currently being processed is an already detected target. If it does not exist, the process proceeds to step ST106 assuming that it is a new detection target. And the speed is obtained, and the prediction processing is performed after incrementing the already detected target number q.
[0079]
In step ST311, from the beat frequency U of the up phase extracted by the current range gate number k and the predicted values K (p) and F (p), the target distance and speed are obtained by the equations (16) and (17). Ask.
[0080]
[Equation 9]

[0081]
Ru and Vu according to equations (8) and (9) can only take discrete values with cτ / 2 as the smallest step, whereas Rs and Vs according to equations (16) and (17) are smaller steps. Can be set. Further, since the equations (16) and (17) are in the form of a kind of tracking filter, it is possible to improve the measurement accuracy of the distance and speed.
[0082]
Further, in step ST312, it is assumed that the target cannot be detected because the up-phase beat frequency U is not extracted or only the up-phase beat frequency U is extracted and the range gate number is smaller than h. It is determined whether there is no target predicted range gate number K (p) that is the same as the current range gate number k. If there is the same number, the process proceeds to step ST313, and if there is no same number, the process proceeds to step ST7.
[0083]
In step ST313, the corresponding K (p) and F (p) are initialized assuming that the already detected target having the same range gate number is lost in step ST312.
[0084]
Subsequently, in step ST314, the already detected target number q is decremented.
[0085]
In subsequent steps ST315 and ST316, the data processing control unit 13 operates so that the value of the detected target number q does not become less than zero.
[0086]
As described above, in the present embodiment, in addition to the effects of the first and second embodiments described above, the target distance at the next observation time is further calculated from the relative distance and relative speed of the target obtained at the current observation time. Since the beat frequency and the range gate number are predicted, and the observation value correlated with the prediction value in the next observation, the target relative distance and relative speed are obtained from the prediction value and the observation value. For a target approaching at high speed from a distance, it is possible to measure a distance and a speed with a small error by detecting the target only with an up-phase beat signal.
[0087]
【The invention's effect】
The present invention is a frequency-modulated modulated wave signal having an up phase in which the frequency gradually increases and a down phase in which the frequency gradually decreases, and is intermittently generated based on the modulated wave signal at a predetermined measurement period interval. A beat signal generation step for generating a beat signal that is a reflected wave at the target of the transmission signal and that indicates a frequency difference from the reception signal shifted from the transmission signal by a Doppler frequency component corresponding to the relative speed of the target; The beat signal is continuously associated with a predetermined distance range in a predetermined period after transmission of each transmission signal. Every predetermined time interval A sampling step for sampling, a data matrix generation step for generating a data matrix for each phase composed of the sampled beat signal and the transmission signal, and the beat signal sampled at a predetermined same number for each transmission signal By specifying a number indicating the sampling order of the data group, a data group reading step for reading from the data matrix, a beat frequency extracting step for analyzing the frequency of the read data group and obtaining a beat frequency, Based on the number and the time interval, the target distance is obtained, and the obtained target distance and The beat frequency extracted in the up phase Frequency sweep width used by radar, frequency sweep time used by radar, wavelength used by radar Based on goal Relative speed of Because it is a distance / velocity measurement method with the required distance / velocity measurement step, for a target approaching at high speed from a long distance, the distance and speed are detected by detecting the target only with the up-phase beat signal. Measurement can be performed with high accuracy.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a transmission / reception device of an FMICW radar.
FIG. 2 is a block diagram showing a configuration of a radar data processing apparatus according to Embodiment 1 of the present invention.
FIG. 3 is an explanatory diagram showing the frequency with respect to time of each signal in the FMICW radar.
FIG. 4 is an explanatory diagram showing connection terminals of the first switch and the second switch in the configuration of FIG. 1 with respect to time.
5 is an explanatory diagram showing a data matrix generated by sampling up-phase and down-phase beat signals in the memory of FIG. 2; FIG.
FIG. 6 is a flowchart showing a data processing procedure of the radar data processing apparatus according to the first embodiment of the present invention.
FIG. 7 is an explanatory diagram showing power attenuation in the FMICW radar when it is out of an ADC band.
FIG. 8 is an explanatory diagram showing an aliasing phenomenon in the FMICW radar when the FFT band is exceeded.
FIG. 9 is a block diagram showing a configuration of a radar data processing apparatus according to a second embodiment of the present invention.
FIG. 10 is a flowchart showing a data processing procedure of the radar data processing apparatus according to the second embodiment of the present invention.
FIG. 11 is a block diagram showing a configuration of a radar data processing apparatus according to a second embodiment of the present invention.
FIG. 12 is a flowchart showing a data processing procedure of the radar data processing apparatus according to the second embodiment of the present invention.
FIG. 13 is a flowchart showing a data processing procedure of the radar data processing apparatus according to the second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Radar transmission / reception apparatus, 2 Transmission / reception control part, 3 Modulation waveform generation part, 4 VCO, 5 1st switch, 6 2nd switch, 7 Antenna, 8 Target, 9a, 9b Distribution circuit, 10 Phase shift circuit, 11a, 11b mixer, 12 radar data processing device, 13 data processing control unit, 14 third switch, 15a, 15b ADC, 16a, 16b memory, 17a, 17b range gate, 18a, 18b frequency extraction unit, 101 extraction result determination unit, 102 2nd distance / speed deriving unit, 201 2nd extraction result determining unit, 202 3rd distance / speed deriving unit, 301 3rd extraction result determining unit, 302 4th distance / speed deriving unit, 303 Speed prediction unit, 304 Frequency / gate number prediction unit.

Claims (8)

A frequency-modulated modulated wave signal having an up phase with a gradually increasing frequency and a down phase with a gradually decreasing frequency, and a target of a transmission signal generated intermittently based on the modulated wave signal at a predetermined measurement period interval A beat signal generating step for generating a beat signal indicating a frequency difference between the reflected signal and a received signal shifted from the transmission signal by a Doppler frequency component corresponding to the target relative velocity;
A sampling step of sampling the generated beat signal at predetermined time intervals continuously corresponding to a predetermined distance range in a predetermined period after transmission of each transmission signal;
A data matrix generation step for generating a data matrix for each phase composed of the sampled beat signal and the transmission signal;
A data group reading step of reading out the data group of the beat signal sampled at a predetermined same number for each transmission signal from the data matrix by designating a number indicating the sampling order;
A beat frequency extraction step for analyzing the frequency of the read data group to obtain a beat frequency;
Based on the number and the time interval, the target distance is obtained, the obtained target distance, the beat frequency extracted in the up phase, the frequency sweep width used in the radar, and the frequency sweep time used in the radar. And a distance / speed measuring step for obtaining a target relative speed based on the wavelength used by the radar and a distance / speed measuring method. In the distance range corresponding to the specified number above, distance and speed measuring method according to claim 1, characterized in that the central value and distance of the target. Based on the beat frequency extracted in the beat frequency extraction step, further comprises a determination step of determining whether or not the beat frequency in the down phase is extracted,
The distance / speed measurement step is as follows:
When it is determined in the determination step that the beat frequency in the down phase has been extracted, the beat frequency extracted in both the up phase and the down phase, the frequency sweep width used in the radar, and the frequency sweep time used in the radar by using the wavelength used in radar and determines the relative velocity of the target,
When it is determined in the determination step that the beat frequency in the down phase has not been extracted, the beat frequency extracted in the up phase, the frequency sweep width used in the radar, the frequency sweep time used in the radar, and the wavelength used in the radar, using, distance and speed measuring method according to claim 1 or 2, wherein the determination of the relative velocity of the target. The distance / speed measurement step is as follows:
When the number is smaller than a preset threshold, the beat frequency extracted in the up phase and the down phase, the frequency sweep width used in the radar, the frequency sweep time used in the radar, and the wavelength used in the radar with bets, determine the relative velocity of the target,
When the number is more than the threshold value, by using the wavelength used by the frequency sweep time and radar used in frequency sweep width and radar used in the beat frequency and the radar extracted in the up phase, relative to the target 3. The distance / speed measuring method according to claim 1, wherein a speed is obtained. From distance and relative velocity of the target obtained by the current observation time, further comprising a prediction step of predicting the beat frequency and the number of the target of the next observation time,
The distance / speed measurement step is as follows:
The observations to correlate with the predicted value at the next observation, from the predicted and observed values, in any one of 4 to claims 1 and obtains the distance and the relative velocity of the target The described distance / speed measuring method. A frequency-modulated modulated wave signal having an up phase with a gradually increasing frequency and a down phase with a gradually decreasing frequency, and a target of a transmission signal generated intermittently based on the modulated wave signal at a predetermined measurement period interval A beat signal generating means for generating a beat signal indicating a frequency difference from a reception signal shifted from the transmission signal by a Doppler frequency component corresponding to the target relative velocity and a reflected wave at
Sampling means for sampling the generated beat signal at predetermined time intervals continuously corresponding to a predetermined distance range in a predetermined period after transmission of each transmission signal;
Data matrix generating means for generating a data matrix for each phase consisting of the sampled beat signal and the transmission signal;
A data group reading means for reading out a data group of the beat signals sampled at a predetermined same number for each transmission signal from the data matrix by designating a number indicating a sampling order;
Beat frequency extraction means for analyzing the frequency of the read data group to obtain the beat frequency,
Based on the number and the time interval, the target distance is obtained, the obtained target distance, the beat frequency extracted in the up phase, the frequency sweep width used in the radar, and the frequency sweep time used in the radar. and based on the wavelength used in radar, radar data processing apparatus characterized by comprising a distance and speed measuring means for obtaining a relative speed of the target. Based on the beat frequency extracted in the beat frequency extraction step, further comprises a determination means for determining whether or not the beat frequency in the down phase is extracted,
The distance / speed measuring means is
When the determination means determines that the beat frequency in the down phase has been extracted, the beat frequency extracted in the up phase and the down phase, the frequency sweep width used in the radar, the frequency sweep time used in the radar, and the radar by using the wavelength used, the seek relative velocity of the target,
When the determination means determines that the beat frequency in the down phase is not extracted, the beat frequency extracted in the up phase, the frequency sweep width used in the radar, the frequency sweep time used in the radar, and the wavelength used in the radar, using radar data processing apparatus according to claim 6, wherein the determination of the relative velocity of the target. The distance / speed measuring means is
When the number is smaller than a preset threshold, the beat frequency extracted in the up phase and the down phase, the frequency sweep width used in the radar, the frequency sweep time used in the radar, and the wavelength used in the radar with bets, determine the relative velocity of the target,
When the number is more than the threshold value, by using the wavelength used by the frequency sweep time and radar used in frequency sweep width and radar used in the beat frequency and the radar extracted in the up phase, relative to the target The radar data processing apparatus according to claim 6 or 7, wherein a speed is obtained.

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