JP2004108851A

JP2004108851A - Angle measuring equipment and communication system using the same

Info

Publication number: JP2004108851A
Application number: JP2002269435A
Authority: JP
Inventors: Yasuhiko Tanabe; 田邉　康彦; Kisho Odate; 大舘　紀章; Hiroki Shiyouki; 庄木　裕樹
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2002-09-17
Filing date: 2002-09-17
Publication date: 2004-04-08

Abstract

<P>PROBLEM TO BE SOLVED: To provide angle measuring algorithm suitable for various circumstances and enable angle measurement of high reliability by controlling an angle measuring means in response to the distance between a signal source and angle measuring equipment. <P>SOLUTION: The angle measuring equipment comprises a plurality of receiving antenna elements, a plurality of receivers corresponding to the antenna elements, a range finder for measuring the distance from the signal source, a control means for selecting an angle measuring means in response to the distance from the signal source, and a goniometer provided with a plurality of angle measuring means. The distance between the signal source and the angle measuring equipment is measured, and the angle measuring algorithm suitable for the state of the signal source is applied based on the measured distance result, thereby performing angle measuring. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、レーダ装置や移動通信の基地局、無線ＬＡＮのアクセスポイント等に適用できる到来波の測角装置、及びこの測角装置を用いた通信装置に関する。
【０００２】
【従来の技術】
レーダ装置や移動通信の基地局、無線ＬＡＮのアクセスポイントにおいては到来する電磁波の方向を精度よく、少ない演算量、高い信頼性で推定する測角装置が望まれている。
【０００３】
高精度・高分解能に測角を行なう推定手法としてアレイアンテナの各素子の受信信号を基にするＭＵＳＩＣ　（Ｍｕｌｔｉｐｌｅ　Ｓｉｇｎａｌ　Ｃｌａｓｓｉｆｉｃａｔｉｏｎ）　法（例えば非特許文献１）やＥＳＰＲＩＴ　（Ｅｓｔｉｍａｔｉｏｎ　ｏｆ　Ｓｉｇｎａｌ　Ｐａｒａｍｅｔｅｒｓ　ｖｉａ　Ｒｏｔａｔｉｏｎａｌ　Ｉｎｖａｒｉａｎｃｅ　Ｔｅｃｈｎｉｑｕｅｓ）　法（例えば非特許文献２）等が存在する。
【０００４】
しかし、これらの推定法は固有値演算を行なうため演算量がアンテナ素子数の３乗に比例して増加してしまう。
【０００５】
また、これらの推定法は到来する電磁波の信号源が点波源であることを想定した手法であるため、信号源が点波源でない場合は特性が劣化してしまう問題点がある。
【０００６】
信号源と測角装置の距離が信号源の大きさに比べて十分離れている場合、信号源は点波源とみなせるが、両者が近接している場合は信号源を点波源とみなせなくなる。
【０００７】
【非特許文献１】
Ｒ。　Ｏ。　Ｓｃｈｍｉｔ、　｀｀Ｍｕｌｔｉｐｌｅ　Ｅｍｉｔｔｅｒ　Ｌｏｃａｔｉｏｎ　ａｎｄ　Ｓｉｇｎａｌ　Ｐａｒａｍｅｔｅｒ　Ｅｓｔｉｍａｔｉｏｎ、”　ＩＥＥＥ　Ｔｒａｎｓ。　Ａｎｔｅｎｎａｓ　Ｐｒｏｐａｇａｔ。　ｖｏｌ。　ＡＰ−３４、　ｎｏ。　３、　ｐｐ。　２７６−２８０、　Ｍａｒｃｈ　１９８６。
【０００８】
【非特許文献２】
Ｒ。　Ｒｏｙ　ａｎｄ　Ｔ。　Ｋａｉｌａｔｈ、　｀｀ＥＳＰＲＩＴ−Ｅｓｔｉｍａｔｉｏｎ　ｏｆ　Ｓｉｇｎａｌ　Ｐａｒａｍｅｔｅｒｓ　ｖｉａ　Ｒｏｔａｔｉｏｎａｌ　Ｉｎｖａｒｉａｎｃｅ　Ｔｅｃｈｎｉｑｕｅｓ、”　ＩＥＥＥ　Ｔｒａｎｓ。　Ａｃｏｕｓｔ。、　Ｓｐｅｅｃｈ、　Ｓｉｇｎａｌ　Ｐｒｏｃｅｓｓｉｎｇ、　ｖｏｌ。　３７、　ｐｐ。９８４−９９５、　Ｊｕｌｙ　１９８６。
【０００９】
【発明が解決しようとする課題】
以上説明したように、信号源が遠方にある場合は信号源が点波源とみなせるため、ＭＵＳＩＣ法やＥＳＰＲＩＴ法などの高分解能推定法を用いることによって高い精度で推定を実現することができる。
【００１０】
しかし、信号源が近接し、なおかつ移動している場合（または受信装置が移動している場合）は遠方に存在する場合に比べて方向の変動が激しいため頻繁に測角を行なう必要があり、演算負荷が大きい手法を適用することが困難になる。
【００１１】
また、信号源が移動はしていなくても近接している場合は、信号源の大きさが無視できず信号源を点波源とみなせなくなってしまう。この結果、信号は特定の方向を中心に多数の方向から到来する（角度広がり）ようになり、到来方向推定精度は劣化し、不安定な推定結果を出力してしまうことになる。
【００１２】
本発明はこのような従来の問題点に鑑みてなされたもので、演算負荷をそれほど増やすことなく測角の信頼性を向上させた測角装置を提供することを目的とする。
【００１３】
【課題を解決するための手段】
上記課題を解決するための本発明の測角装置は、複数のアンテナ素子と、前記アンテナ素子のそれぞれに対応して設けられ、前記アンテナ素子の信号が入力される複数の受信器と、前記複数のアンテナ素子へ到来してくる信号源との距離を測定する測距離手段と、前記複数の受信器で受信した信号がそれぞれ入力され、前記信号源の到来方向を推定するするとともに、その到来方向推定の演算量が異なる複数の測角手段を有する測角器と、前記複数の測角手段の中の一つを選択する制御手段とを具備することを特徴とするものである。
【００１４】
これによれば、測距離を行った結果、信号源が遠距離に存在する場合は信号源が点波源とみなせ、方向の変動も比較的小さいため高分解能推定法を用いるように制御装置は測角法を選択し、測角を行なう。
【００１５】
また、信号源が近接している場合、制御装置は測角法を高分解能推定法から分解能は低いが信頼性の高い推定法を選択し、測角を行なう。この場合、推定精度・分解能は劣化するが、ターゲットが至近距離にあるならばそれほど高い分解能は必要なく、信頼性の高い測角を実現できる。
【００１６】
【発明の実施の形態】
（第１の実施の形態）
以下、本発明の一つの実施の形態について本発明の測角装置１００を通信装置である無線基地局１１０に適用したものを用いて図１を参照しながら説明する。
【００１７】
この第１の実施の形態では、基地局１１０に測角装置１００が搭載され、測角装置からの信号が基地局に供給される構成を示している。測角装置１００は複数の受信アンテナ素子１−１〜１−ｎから構成される受信アンテナ１、アンテナ素子と同数の複数の受信器２−１〜２−ｎ、複数の測角手段を適用できる測角器５、信号源との距離に応じて測角手段を選択する制御装置４、信号源と測角装置の距離を測定する測距離器３、測距離器３に接続された送信アンテナ６から構成される。
【００１８】
また、測角器５にはＭＵＳＩＣ法による測角を行なうＭＵＳＩＣ測角器５−１とビームフォーマー法による測角を行なうビームフォーマー測角器５−２が設けられ、ＭＵＳＩＣ測角器５−１及びビームフォーマー測角器５−２には受信器２−１〜２−ｎの信号がそれぞれ入力される。さらに、測距離器３によって測定された信号源の距離を基に制御装置４からの制御信号によりスイッチ５−３が切り替わりＭＵＳＩＣ測角器又はビームフォーマー測角器の出力が出力される。
【００１９】
なお、この実施の形態では受信アンテナの数を８本（ｎ＝８）とするが、ｎの数はいくつでも良い。
【００２０】
以下に本実施の形態の詳細について説明する。
【００２１】
はじめに受信アンテナ１について説明する。受信アンテナ１は指向性アンテナを形成してもよいし、無指向性アンテナを形成してもよく、所望の周波数帯域において到来する電波を受信するように設計してあれさえすればよいが、ここでは無指向性アンテナが形成されている。
【００２２】
次に受信器２は、周波数変換器やフィルタ、増幅器、ＡＧＣ　（Ａｕｔｏｍａｔｉｃ　Ｇａｉｎ　Ｃｏｎｔｒｏｌ）、Ａ／Ｄ変換機などから構成され、受信アンテナ１で受信したアナログ信号を測角器５が適用できるようにディジタル信号に変換する装置である。
【００２３】
次に測距離器３について説明する。測距離器３は測角を行ないたい到来波の信号源と本発明の測角装置との距離を求める装置である。
【００２４】
測距離器３の例として広帯域な孤立パルスを送信する手法について説明する。広帯域パルスは時間領域の波形がインパルス信号に近いので、広帯域な孤立パルスを送信アンテナ６から送信し、信号源で反射された受信信号を観測することにより直接インパルス応答を測定することができる。このようにして得られたインパルス応答から本発明の測角装置と信号源の間の信号の伝搬時間を推定することができ、信号源と本発明装置との距離を測定することができる。
【００２５】
この測距離器５の測距離の結果から制御装置４が測角手段を選択する。すなわち、制御装置４にはありかじめ設定された閾値をもっており、測距離器５からの測距離値が閾値より大きい場合は信号源は測角装置から遠距離にあると判断し、ＭＵＳＩＣ測角器５−１を選択し、閾値より小さい場合は信号源は測角装置から近距離にあると判断し、ビームフォーマー測角器５−２を選択する。
【００２６】
ここで、図２に示すように到来波の測角を行ないたい信号源２０２とは、レーダ装置のようにターゲットからの直接波を受信する場合はターゲットを表す。また、移動通信のように見通し外伝搬で、電磁波が周囲の建物等から反射や散乱・回折して到来する場合は図３のように周囲の建物等を含めて一つの信号源３０２と考える。
【００２７】
また、図４（ａ）のように信号源４０１と測角装置１００の距離が十分離れている場合は信号源４０１を点波源とみなすことができる。また、信号源４０１が遠距離に存在する場合、信号源４０１、又は測角装置１００が移動していても信号の到来方向はそれほど大きく変動しない。よって、ある程度演算負荷が大きい手法を適用することができる。
【００２８】
次に、図４（ｂ）のように信号源４０２と測角装置１００の距離が近接している場合、信号源４０２が遠方に存在する時と同じ距離を移動しただけでも信号の到来方向は大きく変化してしまう。よって、測角装置１００は遠方に信号源が存在する場合よりも頻繁に測角結果を出力することが必要となり、演算負荷が小さい手法を適用する。
【００２９】
すなわち、信号源が至近距離に存在すると、信号源を点波源とみなすことができなくなる。このような状況でＭＵＳＩＣ測角器５−１のような高分解能な測角手段を用いると、近接した方向から到来し、分離不可能な多数の信号を分離しようと動作してしまうため、十分な特性が得られず不安定な結果を出力してしまう。
【００３０】
この時、制御装置４は分解能がＭＵＳＩＣ測角器５−１よりも低い測角手段である測角を行なうことを選択する。分解能を落とすことによって近接した信号を分離することはできなくなるが、単一の信号源に対しては信号源を点波源とみなせるようになるため測角の信頼性が高くなる。
【００３１】
本実施の形態の測角器５では、演算負荷が大きく分解能が大きいＭＵＳＩＣ法を用いた測角器と演算負荷が小さく分解能が小さいビームフォーマー法を用いた測角器を適用し、それぞれを切り替えている。
【００３２】
したがって、あらかじめ設定した閾値をもとに遠距離の場合はＭＵＳＩＣ測角器５−１を選択し、近距離の場合はビームフォーマー測角器５−２を選択することにより、追従特性が高い測角を提供することができる。また、この測角装置１００からの測角信号を基地局１１０に供給することにより、基地局１１０では図示しない端末の位置を正確に把握することができる。
【００３３】
なお、演算負荷が大きく分解能が大きい測角器としてＭＵＳＩＣ法を用いたＭＵＳＩＣ測角器を説明したが、高分解能推定法の一つであるＥＳＰＲＩＴ法を用いた測角器を適用しても良く、ビームフォーマー測角器のかわりに、ＭＵＳＩＣ法やＥＳＰＲＩＴ法等に比較して分解能は落ちるものの演算負荷の小さいＣａｐｏｎ法を用いた測角器を適用しても良い。
【００３４】
以上説明したように、本発明においては信号源が遠方に存在する場合、制御装置４が高分解能推定法であるＭＵＳＩＣ法を選択し測角を行なう。この結果、推定精度の高い測角を提供することができる。また、これらの手法は複数の信号を分離する能力も高いことから、複数の信号源について測角を行なうことが可能となる。また、信号源が近方に存在する場合、制御装置４が低分解能推定法であるビームフォーマー法を選択し測角を行なう。この結果、信号源が点波源とみなせない場合でも測角を行なうことができる。したがって、距離に応じて追従特性が高く、信頼性の高い測角を提供することができる。
【００３５】
また、本実施の形態では測距離器からは送信アンテナ６を通して孤立パルスを送信する例を示しているが、他の例として、Ｍ系列のように自己相関特性の鋭い信号系列を用いる手法も可能である（参考文献：Ｄ．Ｃ．Ｃｏｘ　ａｎｄ　Ｒ．Ｐ．Ｌｅｃｋ，”Ｄｅｌａｙ　Ｄｏｐｐｌｅｒ　Ｃｈａｒａｃｔｅｒｉｓｔｉｃｓ　ｏｆ　Ｍｕｌｔｉｐａｔｈ　Ｐｒｏｐａｇａｔｉｏｎ　ａｔ　９１０ＭＨｚ　ｉｎ　ａ　ＳｕｂｕｒｂａｎＭｏｂｉｌｅ　Ｒａｄｉｏ　Ｅｎｖｉｒｏｎｍｅｎｔ，”ＩＥＥＥ　Ｔｒａｎｓ．Ａｎｔｅｎｎａｓ　Ｐｒｏｐａｇａｔ．，ｖｏｌ．　ＡＰ−２０，ｎｏ．５，ｐｐ．６２５−６３５，Ｓｅｐｔ．，１９７２）。前述した広帯域な孤立パルスを送信する手法は増幅器への負担が大きく、大規模なレーダ装置では実用可能だが、移動通信や無線ＬＡＮに適用することは困難である。そこで、自己相関特性の鋭い信号系列を送信アンテナから送信し、信号源で反射された信号を受信し、受信信号と送信信号の相互相関を求める。前記信号は自己相関関数がインパルス信号に近い形状をしているため、受信信号と送信信号の相互相関信号はインパルス応答と等価になる。以上の測定によりインパルス応答から伝搬時間を求め、信号源と本発明の測角装置との距離を推測することができる
なお、測距離を行なう手法として上記の２つの例を示したが、本発明では測距離をこれら２つの手法に限定するものではなく、他のいかなる手法を用いても構わない。
（第２の実施の形態）
次に、本発明の第２の実施の形態について図５を用いて説明する。
【００３６】
この第２の実施の形態では測角装置５００は、複数の受信アンテナ素子５１−１〜５１−ｎから構成される受信アンテナ５１、アンテナ素子と同数の複数の受信器５２−１〜５２−ｎ、受信器５２−１〜５２−ｎの出力が入力され、この入力された受信信号の中のいくつかを選択的に出力するスイッチ回路５８、選択された受信出力が入力され、ＭＵＳＩＣ法により信号源の測角を行なう測角器５５、信号源との距離に応じてスイッチ５８を操作して出力する受信信号を選択する制御装置５４、信号源と測角装置の距離を測定する測距離器５３、測距離器５３に接続された送信アンテナ５６から構成される。
【００３７】
さらに、測角装置５００は基地局５１０に搭載され、測角装置の測角データが基地局に供給される。
【００３８】
この図５の測角装置は図１の測角装置と比較して、複数の受信アンテナ素子５１−１〜５１−ｎ、受信器５２−１〜５２−ｎ、測距離器５３、送信アンテナ５７は同じものであり、異なる点は、信号源の距離に応じて制御装置５４が測角に用いるアンテナ素子５−１〜５−ｎ、受信器５−１〜５−ｎの数を減らして測角を行なう点である。
【００３９】
この測角装置５００では、測距離器５３からの測距離の結果から制御装置５４がスイッチ５７に制御信号を供給し、測角器５５に供給する受信信号を選択する。測角器５５に供給する受信信号が減れば測角を行なうアルゴリズムの演算負荷が小さくなることから、信号源が頻繁に移動し分解能が低くてよい近距離での測角に適用できる。
【００４０】
すなわち、制御装置５４ではスイッチ５７を操作して、測距離器５３からの測距離値があらかじめ設定された閾値より大きい場合は信号源は測角装置５００から遠距離にあると判断し、測角器５５に供給する受信信号の数を最大の数とし、演算負荷が大きく分解能が大きい測角を行い、閾値より小さい場合は信号源は測角装置５００から近距離にあると判断し、測角器５５に供給する受信信号の数を減らして、演算負荷が小さく分解能が小さい測角を行っている。
【００４１】
これにより、距離に応じて追従特性が高く、信頼性の高い測角を提供することができる。
【００４２】
以上説明したように、本発明においては信号源の距離に応じて制御装置５４が測角に用いるアンテナ５１と受信器５２を制限する。この結果、分解能を調整することが可能となり、信号源が遠方に存在する場合は高い分解能・高い精度で測角を提供し、信号源が近接している場合は信頼性の高い測角、演算負荷の小さい測角装置を提供することができる。また、この測角装置５００からの測角信号を基地局５１０に供給することにより、基地局５１０では図示しない端末の位置を正確に把握することができる。
【００４３】
なお、スイッチ５７により受信信号の数を選択する場合、選択する受信数（アンテナ素子）は任意に行なうことにより、上記の効果は得られるが、測角の分解能はアンテナの開口長に左右されるので、開口長を小さくするように選択する受信信号数を選択することも可能である。
（第３の実施の形態）
次に、本発明の第３の実施の形態について図６を用いて説明する。
この実施の形態は第１の実施の形態で示した距離に応じて測角器を選択する構成と第２の実施の形態で示した距離に応じてアンテナ素子数（受信信号の数）を選択したものを組み合せたものである。
【００４４】
すなわち、第３の実施の形態では測角装置６００は、複数の受信アンテナ素子６１−１〜６１−ｎから構成される受信アンテナ６１と、アンテナ素子と同数の複数の受信器６２−１〜６２−ｎと、受信器６２−１〜６２−ｎの出力が入力され、この入力された受信信号の中のいくつかを選択的に出力するスイッチ６７と、選択された受信出力が入力され、ＭＵＳＩＣ法により信号源の測角を行なうＭＵＳＩＣ測角器６５−１及びビームフォーマー法により信号源の測角を行なうビームフォーマー測角器６５−２からなる測角器６５、信号源との距離に応じてスイッチ６７を操作して出力する受信信号を選択するとともにＭＵＳＩＣ測角器６５−１及びビームフォーマー測角器６５−２のいづれか一つを選択する制御装置６４、信号源と測角装置の距離を測定する測距離器６３、測距離器６３に接続された送信アンテナ６６から構成される。
【００４５】
さらに、測角装置６００は基地局６１０に搭載され、測角装置の測角データが基地局に供給される。
【００４６】
図６の実施の形態では信号源と本発明の測角装置との距離に応じて、例えば以下に示すようにＭＵＳＩＣ測角器６５−１、ビームフォーマー測角器６５−２、アンテナ素子６１−１〜６１−ｎ数を選択することが可能である。
【００４７】
【表１】

【００４８】
これにより、距離に応じて追従特性が高く、信頼性の高い測角を測角装置を提供することができる。また、この測角装置６００からの測角信号を基地局６１０に供給することにより、基地局６１０では図示しない端末の位置を正確に把握することができる。
（第４の実施の形態）
次に、本発明の第４の実施の形態について図７を用いて説明する。
【００４９】
この第４の実施の形態では測角装置７００は、複数の受信アンテナ素子７１−１〜７１−ｎから構成される受信アンテナ７１と、アンテナ素子と同数の複数の受信器７２−１〜７２−ｎと、複数の測角手段を適用できる測角器７５と、測角器７５の測角結果に応じて測角手段を選択する制御装置７４から構成される。
【００５０】
さらに、測角装置７００は基地局７１０に搭載され、測角装置の測角データが基地局に供給される。
【００５１】
また、測角器７５にはＭＵＳＩＣ測角器７５−１とビームフォーマー測角器７５−２が設けられ、これらの測角器には受信器７２−１〜７２−ｎの信号がそれぞれ入力され、制御装置７４からの制御信号によりスイッチが切り替わりＭＵＳＩＣ測角器７５−１又はビームフォーマー測角器７５−２の出力が出力される。ここではＭＵＳＩＣ測角器７５−１ではＭＵＳＩＣ法による測角を行い、ビームフォーマー測角器７５−２ではビームフォーマー法による測角が行われている。
【００５２】
次に、この実施の形態の動作について説明する。この実施の形態では、信号源と測角装置の距離が時間とともに徐々に近接する状況を想定している。
【００５３】
信号源が測角装置７００に近づく場合は時間とともに角度広がりが大きくなっていき、始めのうちは点波源とみなせた信号源が点波源とみなせなくなる。以上のような状況で、本実施の形態では測角の結果から測角手段を制御する。
【００５４】
すなわち、始めに制御装置７０から測角器７５に対してＭＵＳＩＣ測角器７５−１を選択する制御信号が送られ、ＭＵＳＩＣ測角器７５−１が動作する。信号源が点波源とみなせるほど遠方に存在するので、高い精度・高い分解能で測角を行なうことができる。
【００５５】
この後、信号源が近接するに従い角度広がりが無視できなくなり、ＭＵＳＩＣ測角器７５−１の出力は信号源を一つの信号源とみなせず、単一の信号源に対して複数の信号源が存在するような出力をしてしまう。このような現象が生じた時に制御装置７４は測角手段を分解能が低いビームフォーマー測角器７５−２に切り替える。この結果、測角器７５は信号源を再び単一の信号源とみなすことができる。
【００５６】
このようにこの実施の形態では、測角結果を基に測角結果を制御することによって単一の信号源から複数の信号が到来するほど信号源との距離が近接した場合でも信号源を一つとみなせることができ、信頼性が高い測角を提供することができる。この装置を車載レーダに搭載することにより、障害物に近接した場合に複数の障害物が存在するような誤動作を起こすことがなくなり、安全性が向上する。また、この測角装置７００からの測角信号を基地局７１０に供給することにより、基地局７１０では図示しない端末の位置を正確に把握することができる。
（第５の実施の形態）
次に、第５の実施の形態について図８を用いて説明する。
【００５７】
測角装置８００は、複数の受信アンテナ素子８１−１〜８１−ｎから構成される受信アンテナ８１と、アンテナ素子と同数の複数の受信器８２−１〜８２−ｎと、受信器８２−１〜８２−ｎの出力が入力され、この入力された受信信号の中のいくつかを選択的に出力するスイッチ８７と、選択された受信出力が入力され、ＭＵＳＩＣ法により信号源の測角を行なう測角器８５と、測角器８５の測角結果に応じてスイッチ８７を操作して出力する受信信号を選択する制御装置８４から構成される。
【００５８】
さらに、測角装置８００は基地局８１０に搭載され、測角装置の測角データが基地局に供給される。
【００５９】
この図８の測角装置は図７の測角装置と比較して、複数の受信アンテナ素子８１−１〜８１−ｎ、受信器８２−１〜８２−ｎ、測距離器８３、送信アンテナ８７は同じものであり、異なる点は、信号源の距離に応じて制御装置８４が測角に用いるアンテナ素子８１−１〜８１−ｎ、受信器８２−１〜８２−ｎの数を減らして測角を行なう点である。
【００６０】
この実施の形態は図５の説明で示したように測角器８５に供給する受信信号が減れば測角を行なうアルゴリズムの演算負荷が小さくなることから、信号源が頻繁に移動し、点波源とみなされず、分解能が低くてよい近距離での測角に適用できる。
【００６１】
次に、この実施の形態の動作について説明する。この実施の形態では、信号源と測角装置の距離が時間とともに徐々に近接する状況を想定している。
【００６２】
信号源が測角装置に近づく場合は時間とともに角度広がりが大きくなっていき、始めのうちは点波源とみなせた信号源が点波源とみなせなくなる。以上のような状況で、本実施の形態では測角の結果から測角手段を制御する。
【００６３】
すなわち、始めに制御装置８４から測角器８５に対してすべての受信信号が測角器８５に供給されるようにスイッチ８７を選択する制御信号が送られ、測角器８５が動作する。信号源が点波源とみなせるほど遠方に存在するので、高い精度・高い分解能で測角を行なうことができる。
【００６４】
この後、信号源が近接するに従い角度広がりが無視できなくなり、ＭＵＳＩＣ測角器８５の出力は信号源を一つの信号源とみなせず、単一の信号源に対して複数の信号源が存在するような出力をしてしまう。このような現象が生じた時に制御装置８４はスイッチを切り替えて受信信号の数を減らして測角器に供給する。この結果、８８測角器は信号源を再び単一の信号源とみなすことができる。また、この測角装置８００からの測角信号を基地局８１０に供給することにより、基地局８１０では図示しない端末の位置を正確に把握することができる。
（第６の実施の形態）
次に、本発明の第６の実施の形態について図９を用いて説明する。
【００６５】
この実施の形態では距離と測角結果に応じて測角法を変えるものである。
【００６６】
この実施の形態の測角装置９００は、複数の受信アンテナ素子９１−１〜９１−ｎから構成される受信アンテナ９１と、アンテナ素子と同数の複数の受信器９２−１〜９２−ｎと、複数の測角手段を適用できる測角器９５と、信号源との距離及び測角器９５の測角結果に応じて測角手段を選択する制御装置９４４、信号源と測角装置の距離を測定する測距離器９３、及び測距離器９３に接続された送信アンテナ９７から構成される。
【００６７】
さらに、測角装置９００は基地局９１０に搭載され、測角装置の測角データが基地局に供給される。
【００６８】
また、測角器９５にはＭＵＳＩＣ測角器９５−１とビームフォーマー測角器９５−２が設けられ、これらの測角器には受信器９２−１〜９２−ｎの信号がそれぞれ入力され、測距離器９３によって測定された信号源の距離及び測角器９５の出力を基に制御装置９４からの制御信号によりスイッチ９８が切り替わりＭＵＳＩＣ測角器９５−１又はビームフォーマー測角器９５−２の出力が出力される。ここではＭＵＳＩＣ測角器９５−１ではＭＵＳＩＣ法による測角を行い、ビームフォーマー測角器９５−２ではビームフォーマー法による測角が行われている。
【００６９】
この実施の形態では、上述した実施の形態と同様に、信号源が測角装置に近づく場合は時間とともに角度広がりが大きくなっていき，始めのうちは点波源とみなせた信号源が点波源とみなせなくなり、測距離の結果と測角の結果から測角手段を制御する。
【００７０】
次に図９に示した測角装置９００の動作を図１０のフローチャートにそって説明する。始めに測角装置９００がアンテナ９１により信号源からの信号を受信（ＳＴＥＰ１）したら、測距離器９３により信号源の距離を測定する（ＳＴＥＰ２）。
【００７１】
このとき、信号源が点波源とみなせるほど遠方に存在する時、制御装置９４は測距離の結果を基に分解能の高いＭＵＳＩＣ測角器を選択し（ＳＴＥＰ３），高い精度・高い分解能で測角を行い、複数の信号源の測角結果を提供することができる。
【００７２】
この後、信号源が近接するに従い角度広がりが無視できなくなり、信号源を一つの信号源とみなせず、単一の信号源に対して複数の信号源が存在するような出力をしてしまう。このような現象が生じた時に制御装置９４は測角手段を分解能が低いビームフォーマー測角器に切り替える（ＳＴＥＰ４）。この結果、測角器は信号源を再び単一の信号源とみなすことができる。
【００７３】
さらに信号が近接し，信号源を点波源とみなせなくなった場合、制御装置９４は分解能をさらに低くするように制御を行なう（ＳＴＥＰ５）。これを繰り返すことによって常に安定した測角結果を提供することが可能となる。
【００７４】
したがって、この実施の形態では測角結果を基に測角結果を制御することによって単一の信号源から複数の信号が到来するほど信号源との距離が近接した場合でも信号源を一つとみなせることができ，信頼性が高い測角を提供することができる。また、この測角装置９００からの測角信号を基地局９１０に供給することにより、基地局９１０では図示しない端末の位置を正確に把握することができる。
【００７５】
なお、この第５の実施の形態においても第２の実施の形態と同様に受信器と測角器との間にスイッチを設け、測角器に供給する受信信号変えることにより測角を行なうアルゴリズムの演算負荷を変えることができ、これにより距離に応じて追従特性が高く、信頼性の高い測角を提供することができる。
【００７６】
なお、上記第１乃至第６の実施の形態では信号源が測角装置に時間とともに近づく例をあげて説明したが、信号源が測角装置に時間とともに遠ざかる場合にも適用できる。これは、始めに制御装置で低い分解能または演算負荷が小さい測角手段を選択し、測角を行い、その後に信号源と測角装置との距離に応じて、又は測角器からの測角結果に基づいて測角手段を高い分解能または演算負荷が大きい測角手段に切り替えることにより行なうことができる。
【００７７】
また、上記第１乃至第６の実施の形態では測角器からの測角データを基地局７に供給しているが、基地局７の変わりに車載レーダに搭載することも可能である。これにより、衝突防止用のレーダとして用いると近距離に障害物が存在する場合でも障害物の位置の変化を的確に捉えることができるため、安全性が高まる。また、航空機のレーダに搭載した場合も同様に、障害物や航空機同士のニアミスを未然に防ぐことができる。
【００７８】
また、上記第１、第２、第３、第６の実施の形態では測距離器による信号源の距離の測定を送信アンテナから孤立パルスを送信して、この反射信号をもとに行っていたが、携帯無線システムのようにあらかじめ測角装置より無線端末（信号源）に対して、無線端末が出力する電波を通知し、無線端末からの出力電波を受信して受信信号の減衰度合いにより距離を測定することも可能である。
【００７９】
なお、各実施形態で例示した構成は一例であって、それ以外の構成を排除する趣旨のものではなく、例示した構成の一部を他のもので置き換えたり、例示した構成の一部を省いたり、例示した構成に別の機能を付加したり、それらを組み合わせたりすることなどによって得られる別の構成も可能である。また、例示した構成と論理的に等価な別の構成、例示した構成と論理的に等価な部分を含む別の構成、例示した構成の要部と論理的に等価な別の構成なども可能である。また、例示した構成と同一もしくは類似の目的を達成する別の構成、例示した構成と同一もしくは類似の効果を奏する別の構成なども可能である。
【００８０】
また、各種構成部分についての各種バリエーションは、適宜組み合せて実施することが可能である。
【００８１】
本発明は、上述した実施の形態に限定されるものではなく、その技術的範囲において種々変形して実施することができる。
【００８２】
【発明の効果】
本発明によれば、測角において信号源と本装置と距離を測定し、距離に応じて測角手段を制御するので、分解能の異なる測角手段、演算負荷が異なる測角手段を必要に応じて使い分けることができ、さまざまな伝播環境に対応できる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る測角装置の構成例を示す図
【図２】信号源から直接波が到来し、信号源と本発明装置が近接している状況を説明する図
【図３】信号が見通し外伝搬路を通って伝搬し、信号源と本発明装置が近接している状況を説明する図
【図４】信号源と本発明装置の距離が遠方に存在する場合は信号源を点波源とみなせることを説明する図
【図５】本発明の他の実施形態に係る測角装置の構成例を示す図
【図６】本発明の他の実施形態に係る測角装置の構成例を示す図
【図７】本発明の他の実施形態に係る測角装置の構成例を示す図
【図８】本発明の他の実施形態に係る測角装置の構成例を示す図
【図９】本発明の他の実施形態に係る測角装置の構成例を示す図
【図１０】本発明の他の実施形態に係る測角装置の動作を説明するフロー図
【符号の説明】
１００測角装置
１１０基地局
１受信アンテナ
１−１〜１−ｎアンテナ素子
２−１〜２−ｎ受信器
３測距離器
４制御装置
５測角器
５−１ＭＵＳＩＣ測角器
５−２ビームフォーマー測角器
５−３スイッチ
６送信アンテナ
７スイッチ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an angle measuring device for an incoming wave applicable to a radar device, a base station for mobile communication, an access point of a wireless LAN, and the like, and a communication device using the angle measuring device.
[0002]
[Prior art]
In a radar apparatus, a base station for mobile communication, and an access point of a wireless LAN, there is a demand for an angle measuring apparatus that estimates the direction of an incoming electromagnetic wave with high accuracy, with a small amount of computation, and with high reliability.
[0003]
As an estimation method for performing angle measurement with high accuracy and high resolution, a Multiple Signal Classification (MUSIC) method (for example, Non-Patent Document 1) based on a reception signal of each element of an array antenna, and ESPRIT (Estimation of Signal Parameters via Rotational Information Technology) ) (For example, Non-Patent Document 2).
[0004]
However, since these estimating methods perform eigenvalue calculation, the amount of calculation increases in proportion to the cube of the number of antenna elements.
[0005]
In addition, since these estimation methods assume that the signal source of the arriving electromagnetic wave is a point wave source, there is a problem that the characteristics are deteriorated when the signal source is not a point wave source.
[0006]
When the distance between the signal source and the angle measuring device is sufficiently large compared to the size of the signal source, the signal source can be regarded as a point wave source, but when both are close to each other, the signal source cannot be regarded as a point wave source.
[0007]
[Non-patent document 1]
R. O. Schmit, "Multiple Emitter Location and Signal Parameter Estimation," IEEE Trans. Antennas Propagat. Vol. AP-34, no. 3, pp. 276-280, 86 March.
[0008]
[Non-patent document 2]
R. Roy and T. Keith, @ ESPRIT-Estimation of Signal Parameters via Rotational Innovation Technologies, "IEEE Trans. Acoustics. Speech, Signal Processing, Vol. 99, Vol.
[0009]
[Problems to be solved by the invention]
As described above, when the signal source is far away, the signal source can be regarded as a point wave source, so that the estimation can be realized with high accuracy by using a high-resolution estimation method such as the MUSIC method or the ESPRIT method.
[0010]
However, when the signal source is close and moving (or when the receiving device is moving), the direction changes more rapidly than when the signal source is far away, so it is necessary to frequently perform angle measurement. It becomes difficult to apply a method with a large calculation load.
[0011]
Further, when the signal source is not moving but is close, the size of the signal source cannot be ignored and the signal source cannot be regarded as a point wave source. As a result, the signal comes from many directions (angular spread) around a specific direction, the accuracy of the estimation of the arrival direction is deteriorated, and an unstable estimation result is output.
[0012]
The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide an angle measuring device that improves the reliability of angle measurement without significantly increasing a calculation load.
[0013]
[Means for Solving the Problems]
An angle measuring apparatus according to the present invention for solving the above-mentioned problems includes a plurality of antenna elements, a plurality of receivers provided corresponding to each of the antenna elements, and a plurality of receivers to which signals of the antenna elements are input; Distance measuring means for measuring a distance to a signal source arriving at the antenna element, and signals received by the plurality of receivers are respectively input, and the direction of arrival of the signal source is estimated, and the direction of arrival is estimated. It is characterized by comprising: a goniometer having a plurality of angle measuring means having different amounts of calculation for estimation; and a control means for selecting one of the plurality of angle measuring means.
[0014]
According to this, if the signal source is located at a long distance as a result of the distance measurement, the signal source can be regarded as a point wave source, and since the change in direction is relatively small, the control device measures the signal so as to use the high-resolution estimation method. Select the angle method and measure the angle.
[0015]
When the signal sources are close to each other, the control device selects a low-resolution but high-reliability estimation method from the high-resolution estimation method as the angle measurement method, and performs the angle measurement. In this case, the estimation accuracy and resolution are deteriorated, but if the target is at a close distance, not so high resolution is required, and highly reliable angle measurement can be realized.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 using an apparatus in which the angle measuring apparatus 100 of the present invention is applied to a wireless base station 110 as a communication apparatus.
[0017]
In the first embodiment, a configuration is shown in which the angle measuring device 100 is mounted on the base station 110 and signals from the angle measuring device are supplied to the base station. The angle measuring device 100 can apply a receiving antenna 1 composed of a plurality of receiving antenna elements 1-1 to 1-n, a plurality of receivers 2-1 to 2-n having the same number as the antenna elements, and a plurality of angle measuring means. Angle measuring device 5, control device 4 for selecting angle measuring means according to the distance to the signal source, distance measuring device 3 for measuring the distance between the signal source and the angle measuring device, and transmitting antenna 6 connected to distance measuring device 3 Consists of
[0018]
Further, the goniometer 5 is provided with a MUSIC goniometer 5-1 for performing angle measurement using the MUSIC method and a beamformer goniometer 5-2 for performing angle measurement using the beamformer method. The signals of the receivers 2-1 to 2-n are input to the -1 and the beamformer angle measuring device 5-2, respectively. Further, the switch 5-3 is switched by a control signal from the control device 4 based on the distance of the signal source measured by the distance measuring device 3, and the output of the MUSIC angle measuring device or the beamformer angle measuring device is output.
[0019]
In this embodiment, the number of receiving antennas is eight (n = 8), but the number of n may be any number.
[0020]
The details of the present embodiment will be described below.
[0021]
First, the receiving antenna 1 will be described. The receiving antenna 1 may be formed as a directional antenna or an omnidirectional antenna, and may be designed so as to receive radio waves arriving in a desired frequency band. Thus, an omnidirectional antenna is formed.
[0022]
Next, the receiver 2 includes a frequency converter, a filter, an amplifier, an AGC (Automatic Gain Control), an A / D converter, and the like. The receiver 2 can apply an analog signal received by the receiving antenna 1 to the goniometer 5. This is a device for converting to a digital signal.
[0023]
Next, the distance measuring device 3 will be described. The distance measuring device 3 is a device for calculating the distance between the signal source of the incoming wave to be measured and the angle measuring device of the present invention.
[0024]
A method of transmitting a broadband isolated pulse as an example of the distance measuring device 3 will be described. Since the waveform of the broadband pulse is close to the impulse signal in the time domain, the impulse response can be directly measured by transmitting a broadband isolated pulse from the transmitting antenna 6 and observing the received signal reflected by the signal source. From the impulse response thus obtained, the propagation time of the signal between the angle measuring device of the present invention and the signal source can be estimated, and the distance between the signal source and the device of the present invention can be measured.
[0025]
The control device 4 selects the angle measuring means from the result of the distance measurement by the distance measuring device 5. That is, the control device 4 has a preset threshold value. If the distance measurement value from the distance measuring device 5 is larger than the threshold value, it is determined that the signal source is far from the angle measurement device, and the MUSIC angle measurement is performed. If the signal source is smaller than the threshold value, it is determined that the signal source is located at a short distance from the angle measuring device, and the beamformer angle measuring device 5-2 is selected.
[0026]
Here, as shown in FIG. 2, the signal source 202 for which the angle of the incoming wave is to be measured represents a target when a direct wave from the target is received like a radar device. In addition, when electromagnetic waves arrive by reflection, scattering, and diffraction from surrounding buildings and the like in non-line-of-sight propagation such as mobile communication, it is considered that one signal source 302 includes the surrounding buildings and the like as shown in FIG.
[0027]
When the distance between the signal source 401 and the angle measuring device 100 is sufficiently large as shown in FIG. 4A, the signal source 401 can be regarded as a point wave source. When the signal source 401 is located at a long distance, the arrival direction of the signal does not change so much even if the signal source 401 or the angle measuring device 100 is moving. Therefore, it is possible to apply a method having a relatively large calculation load.
[0028]
Next, as shown in FIG. 4B, when the distance between the signal source 402 and the angle measuring apparatus 100 is short, the direction of arrival of the signal can be changed even if the signal source 402 moves the same distance as when the signal source 402 is far away. It changes greatly. Therefore, the angle measurement device 100 needs to output the angle measurement result more frequently than when the signal source is located in a distant place, and applies a method with a small calculation load.
[0029]
That is, if the signal source is located at a short distance, the signal source cannot be regarded as a point wave source. In such a situation, if a high-resolution angle measuring device such as the MUSIC angle measuring device 5-1 is used, since it operates to separate a large number of signals that arrive from close directions and cannot be separated, it is not sufficient. Characteristic is not obtained and an unstable result is output.
[0030]
At this time, the control device 4 selects to perform angle measurement, which is angle measurement means having a lower resolution than the MUSIC angle measuring device 5-1. Decreasing the resolution makes it impossible to separate adjacent signals, but for a single signal source, the signal source can be regarded as a point wave source, thereby increasing the reliability of angle measurement.
[0031]
In the goniometer 5 of the present embodiment, a goniometer using the MUSIC method with a large calculation load and a large resolution and a goniometer using a beamformer method with a small calculation load and a small resolution are applied. Switching.
[0032]
Therefore, based on a preset threshold, the MUSIC goniometer 5-1 is selected when the distance is long, and the beamformer goniometer 5-2 is selected when the distance is short. Angle measurement can be provided. Further, by supplying the angle measurement signal from the angle measurement device 100 to the base station 110, the base station 110 can accurately grasp the position of a terminal (not shown).
[0033]
Although the MUSIC goniometer using the MUSIC method has been described as a goniometer having a large calculation load and a large resolution, a goniometer using the ESPRIT method, which is one of high-resolution estimation methods, may be applied. Instead of the beamformer goniometer, a goniometer using the Capon method, which has a lower resolution but lower computational load than the MUSIC method or the ESPRIT method, may be applied.
[0034]
As described above, in the present invention, when the signal source is located far away, the control device 4 selects the MUSIC method, which is a high-resolution estimation method, and performs angle measurement. As a result, it is possible to provide an angle measurement with high estimation accuracy. In addition, since these methods have a high ability to separate a plurality of signals, it is possible to perform angle measurement for a plurality of signal sources. When the signal source is located near, the controller 4 selects the beamformer method, which is a low-resolution estimation method, and performs angle measurement. As a result, angle measurement can be performed even when the signal source cannot be regarded as a point wave source. Therefore, it is possible to provide a highly reliable angle measurement with high tracking characteristics according to the distance.
[0035]
Further, in this embodiment, an example is shown in which an isolated pulse is transmitted from the distance measuring device through the transmitting antenna 6. However, as another example, a method using a signal sequence having a sharp autocorrelation characteristic such as an M sequence is also possible. (References: DC Cox and RP Leck, "Delay Doppler Characteristics of Multipath Propagation at 910 MHz in a Suburban Mobile. Radio Env. , Pp. 625-635, Sept., 1972). The above-described method of transmitting a broadband isolated pulse imposes a heavy burden on an amplifier and is practical for a large-scale radar apparatus, but is difficult to apply to mobile communication and wireless LAN. Therefore, a signal sequence having a sharp autocorrelation characteristic is transmitted from a transmitting antenna, a signal reflected by a signal source is received, and a cross-correlation between a received signal and a transmitted signal is obtained. Since the signal has a shape whose autocorrelation function is close to that of the impulse signal, the cross-correlation signal of the reception signal and the transmission signal becomes equivalent to the impulse response. By the above measurement, the propagation time is obtained from the impulse response, and the distance between the signal source and the angle measuring device of the present invention can be estimated.
Although the above two examples have been described as methods for performing distance measurement, the present invention is not limited to distance measurement to these two methods, and any other method may be used.
(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG.
[0036]
In the second embodiment, the angle measuring device 500 includes a receiving antenna 51 including a plurality of receiving antenna elements 51-1 to 51-n, and a plurality of receivers 52-1 to 52-n having the same number as the antenna elements. , Receivers 52-1 to 52-n are inputted, a switch circuit 58 for selectively outputting some of the inputted received signals, a selected received output is inputted, and a signal is inputted by the MUSIC method. A goniometer 55 for measuring the angle of the source, a control device 54 for selecting a received signal to be output by operating a switch 58 according to the distance to the signal source, a rangefinder for measuring the distance between the signal source and the goniometer 53, a transmission antenna 56 connected to the distance measuring device 53;
[0037]
Further, the angle measurement device 500 is mounted on the base station 510, and angle measurement data of the angle measurement device is supplied to the base station.
[0038]
The angle measuring device of FIG. 5 is different from the angle measuring device of FIG. 1 in that a plurality of receiving antenna elements 51-1 to 51-n, receivers 52-1 to 52-n, a distance measuring device 53, and a transmitting antenna 57 are provided. The difference is that the number of antenna elements 5-1 to 5-n and the number of receivers 5-1 to 5-n used by the control device 54 for angle measurement are reduced according to the distance of the signal source. It is a point that makes a corner.
[0039]
In the angle measuring device 500, the control device 54 supplies a control signal to the switch 57 and selects a reception signal to be supplied to the angle measuring device 55 based on the result of the distance measurement from the distance measuring device 53. If the number of received signals supplied to the goniometer 55 is reduced, the computational load of the algorithm for performing goniometry is reduced, so that the present invention can be applied to gogo measurement at short distances where the signal source frequently moves and the resolution may be low.
[0040]
That is, the control device 54 operates the switch 57 to determine that the signal source is far from the angle measuring device 500 when the distance value from the distance measuring device 53 is larger than a preset threshold value. The number of received signals to be supplied to the detector 55 is set to the maximum number, angle calculation with a large computational load and large resolution is performed, and when smaller than the threshold value, the signal source is determined to be at a short distance from the angle measurement device 500, The number of received signals to be supplied to the device 55 is reduced to perform angle measurement with a small calculation load and a small resolution.
[0041]
Thereby, it is possible to provide a highly reliable angle measurement with high tracking characteristics according to the distance.
[0042]
As described above, in the present invention, the control device 54 limits the antenna 51 and the receiver 52 used for angle measurement according to the distance of the signal source. As a result, it is possible to adjust the resolution, provide angle measurement with high resolution and high accuracy when the signal source is far away, and provide highly reliable angle measurement and calculation when the signal source is close. An angle measuring device with a small load can be provided. Further, by supplying the angle measurement signal from the angle measurement device 500 to the base station 510, the base station 510 can accurately grasp the position of a terminal (not shown).
[0043]
When the number of received signals is selected by the switch 57, the above-mentioned effect can be obtained by arbitrarily selecting the number of received signals (antenna elements), but the resolution of angle measurement depends on the aperture length of the antenna. Therefore, it is also possible to select the number of received signals to be selected so as to reduce the aperture length.
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG.
This embodiment is configured to select a goniometer according to the distance shown in the first embodiment and to select the number of antenna elements (the number of received signals) according to the distance shown in the second embodiment. It is a combination of the above.
[0044]
That is, in the third embodiment, the angle measuring device 600 includes a receiving antenna 61 including a plurality of receiving antenna elements 61-1 to 61-n, and a plurality of receivers 62-1 to 62 as many as the number of antenna elements. -N and outputs of the receivers 62-1 to 62-n are input, a switch 67 for selectively outputting some of the input received signals, and a selected reception output are input, and the MUSIC Angle measuring device 65-1 comprising a MUSIC angle measuring device 65-1 for measuring an angle of a signal source by a method and a beamformer angle measuring device 65-2 for measuring an angle of a signal source by a beam former method, and a distance from the signal source. The control device 64 selects the MUSIC goniometer 65-1 and the beamformer goniometer 65-2 by selecting the output signal by operating the switch 67 in accordance with the operation of the switch 67. Dress Distance measuring device measures the distance 63, a transmitting antenna 66 connected to the distance measuring device 63.
[0045]
Further, the angle measurement device 600 is mounted on the base station 610, and angle measurement data of the angle measurement device is supplied to the base station.
[0046]
In the embodiment of FIG. 6, according to the distance between the signal source and the angle measuring device of the present invention, for example, as shown below, a MUSIC angle measuring device 65-1, a beamformer angle measuring device 65-2, an antenna element 61 It is possible to select from -1 to 61-n numbers.
[0047]
[Table 1]

[0048]
This makes it possible to provide a highly reliable angle measurement device that has a high tracking characteristic according to the distance. Further, by supplying the angle measurement signal from the angle measurement device 600 to the base station 610, the base station 610 can accurately grasp the position of a terminal (not shown).
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG.
[0049]
In the fourth embodiment, the angle measuring device 700 includes a receiving antenna 71 including a plurality of receiving antenna elements 71-1 to 71-n, and a plurality of receivers 72-1 to 72- having the same number as the antenna elements. n, a goniometer 75 to which a plurality of goniometers can be applied, and a control device 74 for selecting the goniometer in accordance with the goniometric results of the goniometer 75.
[0050]
Further, the angle measurement device 700 is mounted on the base station 710, and angle measurement data of the angle measurement device is supplied to the base station.
[0051]
The goniometer 75 is provided with a MUSIC goniometer 75-1 and a beamformer goniometer 75-2, and these goniometers receive signals from the receivers 72-1 to 72-n, respectively. Then, the switch is switched by a control signal from the control device 74, and the output of the MUSIC goniometer 75-1 or the beamformer goniometer 75-2 is output. Here, the MUSIC goniometer 75-1 performs angle measurement by the MUSIC method, and the beamformer goniometer 75-2 performs angle measurement by the beamformer method.
[0052]
Next, the operation of this embodiment will be described. In this embodiment, it is assumed that the distance between the signal source and the angle measuring device gradually approaches with time.
[0053]
When the signal source approaches the angle measurement device 700, the angular spread increases with time, and a signal source initially regarded as a point wave source cannot be regarded as a point wave source. In the above situation, the present embodiment controls the angle measuring means based on the result of angle measurement.
[0054]
That is, first, a control signal for selecting the MUSIC angle measuring device 75-1 is transmitted from the control device 70 to the angle measuring device 75, and the MUSIC angle measuring device 75-1 operates. Since the signal source exists so far as to be regarded as a point wave source, angle measurement can be performed with high accuracy and high resolution.
[0055]
Thereafter, as the signal sources approach, the angular spread cannot be ignored, and the output of the MUSIC goniometer 75-1 does not consider the signal sources as one signal source, and a plurality of signal sources for a single signal source. Outputs as if it existed. When such a phenomenon occurs, the control device 74 switches the angle measuring means to the beamformer angle measuring device 75-2 having a low resolution. As a result, the goniometer 75 can again regard the signal source as a single signal source.
[0056]
As described above, in this embodiment, by controlling the angle measurement result based on the angle measurement result, even if the distance from the signal source becomes shorter as a plurality of signals arrive from a single signal source, the signal source is unified. It is possible to provide a highly reliable angle measurement. By mounting this device in an on-vehicle radar, a malfunction such as a plurality of obstacles does not occur when approaching an obstacle, thereby improving safety. Further, by supplying the angle measurement signal from the angle measurement device 700 to the base station 710, the base station 710 can accurately grasp the position of a terminal (not shown).
(Fifth embodiment)
Next, a fifth embodiment will be described with reference to FIG.
[0057]
The angle measuring device 800 includes a receiving antenna 81 including a plurality of receiving antenna elements 81-1 to 81-n, a plurality of receivers 82-1 to 82-n having the same number as the antenna elements, and a receiver 82-1. ８２82-n are input, a switch 87 for selectively outputting some of the input received signals and a selected received output are input, and the angle of the signal source is measured by the MUSIC method. It is composed of a goniometer 85 and a control device 84 that operates a switch 87 in accordance with the angle measurement result of the goniometer 85 to select a received signal to be output.
[0058]
Further, the angle measurement device 800 is mounted on the base station 810, and angle measurement data of the angle measurement device is supplied to the base station.
[0059]
The angle measuring device of FIG. 8 is different from the angle measuring device of FIG. 7 in that a plurality of receiving antenna elements 81-1 to 81-n, receivers 82-1 to 82-n, a distance measuring device 83, and a transmitting antenna 87 are provided. The difference is that the number of antenna elements 81-1 to 81-n and the number of receivers 82-1 to 82-n used for angle measurement by the control device 84 are reduced according to the distance of the signal source. It is a point that makes a corner.
[0060]
In this embodiment, as shown in the description of FIG. 5, if the number of received signals supplied to the goniometer 85 is reduced, the calculation load of the algorithm for performing the angle measurement is reduced, so that the signal source frequently moves and the point wave source Therefore, the present invention can be applied to the angle measurement at a short distance where the resolution may be low.
[0061]
Next, the operation of this embodiment will be described. In this embodiment, it is assumed that the distance between the signal source and the angle measuring device gradually approaches with time.
[0062]
When the signal source approaches the angle measurement device, the angular spread increases with time, and a signal source that was initially regarded as a point wave source cannot be regarded as a point wave source. In the above situation, the present embodiment controls the angle measuring means based on the result of angle measurement.
[0063]
That is, first, a control signal for selecting the switch 87 is sent from the control device 84 to the angle measuring device 85 so that all the received signals are supplied to the angle measuring device 85, and the angle measuring device 85 operates. Since the signal source exists so far as to be regarded as a point wave source, angle measurement can be performed with high accuracy and high resolution.
[0064]
Thereafter, as the signal sources approach, the angular spread cannot be ignored, and the output of the MUSIC goniometer 85 does not regard the signal sources as one signal source, and there are a plurality of signal sources for a single signal source. Output like this. When such a phenomenon occurs, the control device 84 switches a switch to reduce the number of received signals and supplies the signals to the goniometer. As a result, the 88 goniometer can again consider the signal source as a single signal source. Further, by supplying the angle measurement signal from the angle measurement device 800 to the base station 810, the base station 810 can accurately grasp the position of a terminal (not shown).
(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIG.
[0065]
In this embodiment, the angle measurement method is changed according to the distance and the angle measurement result.
[0066]
The angle measuring device 900 of this embodiment includes a receiving antenna 91 including a plurality of receiving antenna elements 91-1 to 91-n, a plurality of receivers 92-1 to 92-n having the same number as the number of antenna elements, A goniometer 95 to which a plurality of goniometers can be applied, a control device 944 for selecting a goniometer in accordance with the distance between the signal source and the goniometric result of the goniometer 95, and a distance between the signal source and the goniometer. It comprises a distance measuring device 93 for measuring and a transmission antenna 97 connected to the distance measuring device 93.
[0067]
Further, the angle measurement device 900 is mounted on the base station 910, and angle measurement data of the angle measurement device is supplied to the base station.
[0068]
The goniometer 95 is provided with a MUSIC goniometer 95-1 and a beamformer goniometer 95-2, and these goniometers receive signals from the receivers 92-1 to 92-n, respectively. The switch 98 is switched by a control signal from the control device 94 based on the distance of the signal source measured by the distance measuring device 93 and the output of the angle measuring device 95, and the MUSIC angle measuring device 95-1 or the beamformer angle measuring device is used. 95-2 is output. Here, the MUSIC goniometer 95-1 performs angle measurement by the MUSIC method, and the beamformer goniometer 95-2 performs angle measurement by the beamformer method.
[0069]
In this embodiment, similarly to the above-described embodiment, when the signal source approaches the angle measurement device, the angular spread increases with time, and at first, the signal source regarded as a point wave source becomes the point wave source. The angle measuring means is controlled based on the distance measurement result and the angle measurement result.
[0070]
Next, the operation of the angle measuring device 900 shown in FIG. 9 will be described with reference to the flowchart of FIG. First, when the angle measuring device 900 receives a signal from a signal source through the antenna 91 (STEP 1), the distance to the signal source is measured by the distance measuring device 93 (STEP 2).
[0071]
At this time, when the signal source is far enough to be regarded as a point wave source, the control device 94 selects a MUSIC goniometer having a high resolution based on the result of the distance measurement (STEP 3), and performs angle measurement with high accuracy and high resolution. To provide angle measurement results of a plurality of signal sources.
[0072]
Thereafter, as the signal sources approach each other, the angular spread cannot be ignored, and the signal sources cannot be regarded as one signal source, and an output is made such that a plurality of signal sources exist for a single signal source. When such a phenomenon occurs, the control device 94 switches the angle measuring means to a beamformer angle measuring device having a low resolution (STEP 4). As a result, the goniometer can again regard the signal source as a single signal source.
[0073]
When the signal further approaches and the signal source cannot be regarded as a point wave source, the control device 94 performs control to further lower the resolution (STEP 5). By repeating this, it is possible to always provide a stable angle measurement result.
[0074]
Therefore, in this embodiment, by controlling the angle measurement result based on the angle measurement result, the signal source can be regarded as one even when the distance from the signal source becomes shorter as a plurality of signals arrive from a single signal source. And a highly reliable angle measurement can be provided. Further, by supplying the angle measurement signal from the angle measurement device 900 to the base station 910, the base station 910 can accurately grasp the position of a terminal (not shown).
[0075]
In the fifth embodiment, similarly to the second embodiment, an algorithm for providing a switch between a receiver and a goniometer and performing angle measurement by changing a received signal supplied to the goniometer. Can be changed, thereby providing a highly reliable angle measurement with high tracking characteristics according to the distance.
[0076]
In the first to sixth embodiments, an example has been described in which the signal source approaches the angle measuring device with time. However, the present invention is also applicable to the case where the signal source moves away from the angle measuring device with time. This means that the controller first selects the angle measuring means with low resolution or computational load, performs angle measurement, and then determines the angle according to the distance between the signal source and the angle measuring device or from the angle measuring device. It can be performed by switching the angle measuring means to a high resolution or an angle measuring means having a large calculation load based on the result.
[0077]
In the first to sixth embodiments, the angle measurement data from the angle measuring device is supplied to the base station 7. However, the angle measuring data may be mounted on a vehicle-mounted radar instead of the base station 7. As a result, when the radar is used as a collision prevention radar, a change in the position of an obstacle can be accurately detected even when an obstacle is present at a short distance, thereby increasing safety. Similarly, in the case of being mounted on the radar of an aircraft, it is possible to prevent obstacles and near-miss between the aircraft in advance.
[0078]
In the first, second, third, and sixth embodiments, the distance measurement of the signal source by the distance measuring device is performed by transmitting an isolated pulse from the transmitting antenna and based on the reflected signal. However, as in a portable radio system, the angle measuring device notifies the radio terminal (signal source) of the radio wave output from the radio terminal in advance, receives the radio wave output from the radio terminal, and determines the distance according to the degree of attenuation of the received signal. Can also be measured.
[0079]
The configuration illustrated in each embodiment is merely an example, and is not intended to exclude other configurations. Some of the illustrated configurations may be replaced with others, or some of the illustrated configurations may be omitted. Alternatively, another configuration obtained by adding another function to the illustrated configuration, combining them, or the like is also possible. Further, another configuration that is logically equivalent to the illustrated configuration, another configuration that includes a portion that is logically equivalent to the illustrated configuration, another configuration that is logically equivalent to the main part of the illustrated configuration, and the like are also possible. is there. Further, another configuration that achieves the same or similar purpose as the illustrated configuration, another configuration that achieves the same or similar effect as the illustrated configuration, and the like are also possible.
[0080]
Further, various variations of various components can be implemented in appropriate combinations.
[0081]
The present invention is not limited to the above-described embodiment, and can be implemented with various modifications within the technical scope thereof.
[0082]
【The invention's effect】
According to the present invention, the distance between the signal source and the device is measured in angle measurement, and the angle measurement means is controlled in accordance with the distance. And can be used for various propagation environments.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of an angle measuring device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a situation in which a direct wave comes from a signal source and the signal source and the device of the present invention are close to each other.
FIG. 3 is a diagram for explaining a situation in which a signal propagates through a non-line-of-sight propagation path and a signal source and the device of the present invention are close to each other.
FIG. 4 is a diagram for explaining that a signal source can be regarded as a point wave source when the distance between the signal source and the apparatus of the present invention is far;
FIG. 5 is a diagram showing a configuration example of an angle measuring device according to another embodiment of the present invention.
FIG. 6 is a diagram showing a configuration example of an angle measuring device according to another embodiment of the present invention.
FIG. 7 is a diagram showing a configuration example of an angle measuring device according to another embodiment of the present invention.
FIG. 8 is a diagram showing a configuration example of an angle measuring device according to another embodiment of the present invention.
FIG. 9 is a diagram showing a configuration example of an angle measuring device according to another embodiment of the present invention.
FIG. 10 is a flowchart illustrating the operation of an angle measuring device according to another embodiment of the present invention.
[Explanation of symbols]
100 angle measuring device
110 base stations
One receiving antenna
1-1 to 1-n antenna elements
2-1 to 2-n receiver
3 rangefinder
4 control unit
5 goniometer
5-1 MUSIC goniometer
5-2 beamformer goniometer
5-3 switch
6 transmitting antennas
7 switches

Claims

A plurality of antenna elements,
A plurality of receivers provided corresponding to each of the antenna elements, to which a signal of the antenna element is input,
Distance measuring means for measuring a distance to a signal source arriving at the plurality of antenna elements,
Each of the signals received by the plurality of receivers is input, and while estimating the arrival direction of the signal source, the amount of calculation of the arrival direction estimation has a plurality of angle measuring devices having different angle measuring means,
Controlling means for selecting one of the plurality of angle measuring means.

2. The angle measuring apparatus according to claim 1, wherein the control means selects the plurality of angle measuring means of the angle measuring device according to a distance measuring output of the distance measuring means.

2. The method according to claim 1, wherein the control means selects one of the angle measuring means from the distance measuring means, and switches to another angle measuring means according to the angle measuring output of the selected angle measuring means. Item 3. The angle measuring device according to Item 2.

Selecting means for selecting the received signal input to the angle measuring means, wherein the angle measuring is performed based on at least one result of the distance measuring output of the distance measuring means or the angle measuring output of the selected angle measuring means. 4. The angle measuring apparatus according to claim 1, wherein the received signal input to the means is changed.

The angle measuring device according to claim 4, wherein the selection of the reception signal input to the angle measuring means changes an aperture length of the antenna by the antenna element.

The plurality of angle measuring means are a first angle measuring means and a second angle measuring means, the first angle measuring means is a MUSIC method or an ESPRIT method, and the second angle measuring means is a beamformer. The angle measuring device according to claim 1, wherein the angle measuring device is a Mer method or a Capon method.

2. The angle measuring device according to claim 1, wherein the distance measuring means includes means for transmitting an isolated pulse.

2. The angle measuring device according to claim 1, wherein the distance measuring device has a means for transmitting a signal sequence having an autocorrelation characteristic and calculating a cross-correlation function between a received signal and a transmitted signal.

10. A communication device, wherein an angle measurement output for a communication partner is input by the angle measurement device according to claim 1, and communication is performed to the communication partner whose position is specified based on the input signal. .