JP3700264B2

JP3700264B2 - Wireless device

Info

Publication number: JP3700264B2
Application number: JP18459796A
Authority: JP
Inventors: 照恵松村; 良雄堀池; 孝之末松
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1996-07-15
Filing date: 1996-07-15
Publication date: 2005-09-28
Anticipated expiration: 2016-07-15
Also published as: JPH1032504A

Description

【０００１】
【発明の属する技術分野】
本発明は無線信号も用いて信号のやりとりをする無線装置に関するものである。
【０００２】
【従来の技術】
従来より無線装置は信号強度等から信号ありと判断した場合に動作を開始し、特定信号の検出を行いながら一定時間の経過により信号なしと判断する信号判定手段を用いて構成されていた。特に、検針用無線装置には、こうした方式を省電力の観点から応用し、特定信号の検出を開始してからも信号強度を監視し、強度低下時には直ちにキャリアなしと判断し受信終了する信号判定手段を用いたものもあり、そうした無線装置を用いたものは特開平８−１０２６８４号公報に記載されている。この装置は信号判定手段の図１０の流れ図に示すように、電波強度を確認（キャリアセンス）し（ｓｔｅｐ１）、キャリアが検出されなければ受信を終了し（ｓｔｅｐ２から７へ）、電波ありと判定されればビット同期検出を開始し（ｓｔｅｐ２から３へ）、検出が終了すれば以降の電文を受信し（ｓｔｅｐ４から５、６のループへ）、データ終了により受信終了（ｓｔｅｐ６から７へ）する。また、ビット同期検出ができない場合（ｓｔｅｐ４でＮｏ判定）には、規定時間Ｔｈの経過を判定し（ｓｔｅｐ８）、規定時間Ｔｈをすぎれば受信を終了して（ｓｔｅｐ８から７へ）待機状態に戻るようになっていた。
【０００３】
【発明が解決しようとする課題】
しかしながら上記従来の無線装置では、信号の有無を最初に判断し、以後一定時間の経過のみで受信終了する方式の場合には、最初の信号強度が取れれば時間の経過のみで他システム信号かどうかの判定をしているため、いかなる信号であっても必要時間（上記従来例Ｔｈ）の受信を強いられることとなり、消費電流の点で無駄が多い構成となっていた。また、信号の有無を瞬時のキャリア判定で行い、キャリアが無くなれば受信終了する方式では瞬間的なキャリアレベルの低下や受信強度信号へのノイズの混入等により、誤判定が起こりやすく信号受信率が低下するという課題があった。
【０００４】
特に検針用無線装置では、検針員が携帯無線機を持ち歩いて手動で検針する場合と電話回線を用いて自動的に検針する２つの形態が一般的だが、どちらも時間当たりの検針件数を高くできなければ人件費または電話回線使用料（電話料金）が高くなり、採算を維持できない。このため、通信の信頼性をできる限りため、効率的に検針する必要がある。ところが、こうした無線装置は用途上、屋外、道路付近等に取り付けられる可能性が高く、家屋内外の機器等からのノイズ以外に、通行する車やオートバイ、人等からのイグニッションノイズを高い頻度で受け、このノイズをキャリアセンスすることにより受信動作に移行しやすくなっていたり、逆に周囲を車両等が通過することで電波の伝搬に影響を受け、電波強度が一時的に低下するフェージングという現象が発生し、放射されている電波を受信できなくなり、受信不良となる可能性が高い。そこでこうしたノイズの影響を受けず、通信信頼性を向上させることが第１の課題である。
【０００５】
一方、こうした装置は、設置場所等の制約から完全密閉型の電池駆動となることが一般的で、長期間（例えばメータ検定満期の１０年）の動作保証（メンテナンスフリー）が要望としてある。そして、この要望が達成できなければ、装置を設置した全戸に対しこの保証期間に応じた頻度で交換作業を行わなくてはならず、装置の費用や交換作業による人件費等が増大することになる。このためできる限り電池寿命の伸長を計り、保証期間の伸長が必要となるが、上述した雑多なノイズやイグニッションノイズを受信してしまうと、その頻度に応じて受信動作による電流消費が増大する。幹線道路付近等、車両の通行量が多い場合には、高い頻度で発生し、電流消費が大きくなるが、こうした条件下での現象であっても、全装置の保証期間が最悪の条件での保証となるため、結果的に保証期間が短くなり、上記の課題が顕著に表れる。また、電波環境のよいところでは必要以上の頻度で交換することとなり無駄も大きい。ノイズ等不確定要素による受信時間の増加を少なくし、これにより電流増加を少なくかつ条件によらず一定に近づけることが第２の課題である。
【０００６】
【課題を解決するための手段】
本発明は上記課題を解決するために信号の受信開始後に受信強度の確認と、判定値以下のレベルが継続した時間の計測を行い、判定時間以上連続して判定値以下のレベルが継続すれば信号の受信を中止するものである。
【０００７】
上記発明によれば信号受信開始後に発生する電波強度の変化を検出し、信号受信処理を中止することができる。
【０００８】
【発明の実施の形態】
本発明の無線装置は、無線信号の受信強度が判定値以上となったことにより復調信号の受信を開始し、受信強度が判定値以下となる時間が判定時間以上連続した場合に信号受信を中止するものである。これにより短いノイズにより誤って受信終了することがなく、受信強度の異常に対し、早期に異常判定して受信動作を中止することが可能となり受信信頼性の向上が得られる。
【０００９】
また、無線信号の受信強度が判定値以上となったことにより復調信号の受信を開始し、受信強度が判定値以下となる時間が単位時間当たり所定の時間以上となった場合に信号受信を中止するものである。これにより短いノイズが頻繁に発生する等の異常に対し、早期に判定して受信動作を停止することができが可能となり受信信頼性の向上ができるものである。
【００１０】
また、無線信号の受信強度が判定値以上となったことにより復調信号のビット同期検出を開始し、受信強度が判定値以下となる時間が判定時間以上連続した場合にビット同期検出を中止するものである。これにより短いノイズによりビット同期検出を中断することがなく、受信強度の異常に対し早期に異常判定して受信動作を停止するので、受信率が向上する。特にビット同期検出では、ビット同期検出を複数回試行するために十分なビット同期長を確保されていることが一般的であるため、受信強度以上の発生後も受信を中断しないことによる受信信頼性向上の効果が大きい。
【００１１】
また、無線信号の受信強度が判定値以上となったことにより復調信号のビット同期検出を開始し、受信強度が判定値以下となる時間が単位時間当たり所定の時間以上となった場合にビット同期検出を中止するものである。これにより短いノイズが頻繁に発生する等の異常に対し、早期に判定して受信動作を停止することができ、ノイズを受信することにより増加する消費電流の低減が可能となるものである。特にビット同期検出では、ビット同期検出を複数回試行するために十分なビット同期長を確保されていることが一般的であるため、受信強度以上の発生後も受信を中断しないことによる受信信頼性向上の効果が大きい。
【００１２】
また、ビット同期検出完了により復調信号のフレーム同期検出を開始し、受信強度が判定値以下となる時間が判定時間以上連続した場合にフレーム同期検出を中止するものである。これにより短いノイズによりフレーム同期検出を中断することなく、長いノイズによるバースト誤り発生の可能性を検出し、フレーム同期の誤検出の可能性を早期に異常判定して受信動作を停止でき、信頼性が向上する。
【００１３】
また、ビット同期検出完了により復調信号のフレーム同期検出を開始し、受信強度が判定値以下となる時間が単位時間当たり所定の時間以上となった場合にフレーム同期検出を中止するものである。これにより短いノイズによりフレーム同期検出を中断することなく、こうしたノイズが頻繁に発生する等の異常によるランダム誤りの可能性を早期に検出し、フレーム同期検出の誤検出の可能性を早期に異常判定して受信動作を停止することができ、信頼性が向上する。
【００１４】
また、ビット同期信号を含むヘッダー信号を付与したデータ要求信号を送信し、電池で駆動されその信号に対する応答信号を受信してデータを収集する収集側無線機と、データ要求信号を受信すると検針値等を応答する検針側無線機とから構成され、検針側無線機は無線信号を受信する受信手段と、受信手段を定期的に駆動する駆動手段と、受信される信号の強度を所定のレベルと比較するキャリアセンス手段と、受信される信号を処理る信号判定手段と、信号判定手段によりデータ要求信号を受信した場合に検針値等を無線信号で応答する検針値応答手段とを有しているものである。そして、駆動手段が受信手段を駆動し、キャリアセンス手段がこの受信される信号の強度を測定し、信号判定手段は、受信強度が判定値以上となったことにより受信手段により受信される信号のビット同期検出を開始し、さらにこの間受信強度が判定値以下となる時間が判定時間以上連続した場合にビット同期検出および駆動手段を介して受信手段の受信動作を中止することができる。これによりフェージング等の短いノイズによりビット同期検出を中断することがなくなるため、通信の成功率が向上するとともに、受信強度の異常に対し早期に異常判定して受信動作を停止するため、ノイズを受信することにより増加する消費電流が低減し電池寿命の延長につながるものである。
【００１５】
また、駆動手段が受信手段を駆動し、キャリアセンス手段がこの受信される信号の強度を測定し、信号判定手段は、受信強度が判定値以上となったことにより受信手段により受信される信号のビット同期検出を開始し、さらにこの間、予め定められた単位時間毎に受信強度が判定値以下となる時間を通算し、所定の時間以上となった場合にビット同期検出および駆動手段を介して受信手段の受信動作を中止するため、短いノイズにより受信を中断することなく、フェージングが異常に多発するなどして平均受信レベルが十分取れない場合に受信を中止することができる。これにより電波環境の異常等により平均受信レベルが十分取れない等の異常に対し、早期に判定して受信動作を停止することができるため、誤判定、誤動作の恐れがなく、受信率が向上するとともにノイズを受信することにより増加する消費電流が低減し電池寿命の延長につながるものである。
【００１６】
また駆動手段が受信手段を駆動し、キャリアセンス手段がこの受信される信号の強度を測定し、信号判定手段は、受信強度が判定値以上となったことにより受信手段により受信される信号のビット同期検出を開始し、さらにビット同期が検出されるとフレーム同期検出を開始し、さらにこの間受信強度が判定値以下となる時間が判定時間以上連続した場合にフレーム同期検出および駆動手段を介して受信手段の受信動作を中止するため、受信中の電波強度の変化により受信を中断することができる。このため短いノイズによりフレーム同期検出を中断することなく、バースト誤りの可能性とそれによるフレーム同期の誤検出の可能性を早期に異常判定して受信動作を停止でき、通信信頼性を向上させ誤動作等の危険をなくすことができる。また、ノイズを受信することにより増加する消費電流が低減し電池寿命の延長につながるものである。
【００１７】
また駆動手段が受信手段を駆動し、キャリアセンス手段がこの受信される信号の強度を測定し、信号判定手段は、受信強度が判定値以上となったことにより受信手段により受信される信号のビット同期検出を開始し、さらにビット同期検出完了により復調信号のフレーム同期検出を開始し、さらにこの間、予め定められた単位時間毎に受信強度が判定値以下となる時間を通算し、所定の時間以上となった場合にフレーム同期検出および駆動手段を介して受信手段の受信動作を中止するため、平均受信レベルが十分取れない場合に受信を中止することができる。このため平均受信レベルが十分でなく短いノイズが頻繁に発生する等の異常によるランダム誤りの可能性とそれによるフレーム同期検出の誤検出の可能性を早期に異常判定して受信動作を停止することができ、通信の信頼性が向上するとともに、ノイズを受信することにより増加する消費電流の低減を可能にするものである。
【００１８】
以下本発明の無線装置の実施例を図面を用いて説明する。
【００１９】
（実施例１）
請求項１、請求項３、請求項７の実施例を図１〜４を用いて説明する。図１は本発明の実施例１の無線装置における検針用無線装置のブロック図である。また図２、図３は信号の送受信を説明するためのタイミングチャートであり、図４は信号判定手段の動作を示す流れ図である。
【００２０】
図１において、１は検針用無線装置であり収集側無線機２と検針側無線機３から構成されている。４はメータであり、このメータ４の検針値が検針用無線装置１を介してデータ収集装置５に収集されるようになっている。収集側無線機２はヘッダーを含むデータ要求信号を送信し、検針側無線機３は電源である電池３７を内蔵し、タイマ部３２が間欠受信のためのタイミングを作成し、そのタイミングに従って、駆動手段３１が受信手段３３の無線信号の復調可能な受信状態にする。３４は受信する電波の受信強度を測定し、所定のレベル（Ｅｓ）と比較することによりキャリアの有無を判定するキャリアセンス手段である。３５は信号判定手段であり、受信手段３３が駆動手段３１により受信可能状態となり、かつキャリアセンス手段３４によりキャリアが検出されると、受信手段３３からの復調信号を解析し、ビット同期検出、フレーム同期検出、要求信号の受信を行う。３６は応答手段であり、信号判定手段３５で要求信号が確認された場合にメータ４からの検針値データを応答信号として収集側無線機２に送る。収集側無線機２はこの応答信号を受信し、データ収集装置５に検針値データを格納する。
【００２１】
図２は本実施例の送受信動作を説明するためのタイミングチャートであり、収集側無線機２から送信される信号のパケット構成としてビット同期信号ａおよびフレーム同期信号ｂを含むヘッダー信号ｃを繰り返した後データ要求信号ｄを付加している。
【００２２】
次に信号判定手段の詳細な受信動作について図２、図３のタイミングチャートのタイミングに沿って図４の流れ図を用いて説明する。電流消費を抑えるため駆動手段３１は収集側無線機２からの信号長に応じたサンプリング周期（Ｔｓ）で受信手段３３を駆動している。受信手段３３が駆動されるとキャリアセンス手段３４がキャリアセンスを行い（ｓｔｅｐ１）、キャリアが検出されなければ受信動作を終了させ（ｓｔｅｐ１から１１へ）、キャリアがあれば（ｓｔｅｐ２のＹｅｓ）タイムアウト時間Ｔを初期化して計測開始し（ｓｔｅｐ３）、キャリアを確認しながら（ｓｔｅｐ４、５）、キャリアがあれば受信強度が判定値以下となる時間である時間ｔの計測を初期化して計測開始し（ｓｔｅｐ６）、ビット同期の検出を行う（ｓｔｅｐ７）。ビット同期が検出されるまで時間Ｔの経過を確認し（ｓｔｅｐ１３）ながら上記作業を継続する（ｓｔｅｐ４から８、１３のループ）。なお、このタイムアウト時間Ｔはヘッダー信号の構成を基準にしきい値を決めており、本実施例ではヘッダー長Ｔｈを基準とする。
【００２３】
今、他システムからの信号または短時間のノイズ（長さｔ１）を受信した場合、受信タイミング（３ア）から受信を開始し、ビット同期の検出をおこなう（ｓｔｅｐ７）が、ノイズが終了（３イ）しキャリアが検出されなくなると（ｓｔｅｐ５から１２へ）初期化後の経過時間として時間ｔの計測が進む。この時間ｔは、フェージング等による電波の揺らぎに要する時間を基準にｔｂをしきい値（判定時間）としており、キャリアの検出されない時間がｔｂを超えると（３ウ）、時間Ｔｈ経過以前でも受信動作を終了させる（ｓｔｅｐ１２からｓｔｅｐ１１へ）。これにより継続時間の短いイグニッションノイズや機器からのノイズを早期に受信終了することが可能となる。
【００２４】
また、ビット同期検出途上に時間ｔ２のフェージングを受けた場合の動作では、受信タイミング（３エ）からキャリアが検出され（ｓｔｅｐ２から３、４、５、６へ）受信を開始し、ビット同期の検出を行う（ｓｔｅｐ７）。ここで、フェージングが発生し（３オ）、キャリアが検出されなくなると（ｓｔｅｐ５から１２へ）、時間ｔが計測開始されるが、フェージングがｔ２（＜ｔｂ）で終了するため、時間ｔの判定（ｓｔｅｐ１２）において超過することがなく（ｓｔｅｐ１２から４へ）、時間ｔ２の経過とともにキャリアが検出され、再度ビット同期検出を行う（ｓｔｅｐ５から６へ）ため無事に受信が可能となる。
【００２５】
なお、ｔｂの時間は検針用無線装置に対し、周囲環境の影響範囲（距離）と影響範囲内を移動する車両等の標準移動時間のを基準に定める。例えば道路上で影響する範囲が３ｍにわたり、通過する車両の時速を６０ｋｍ／ｈとした場合には０．１８秒間のフェージングが予め予想されるため、０．０２秒の設計余裕を取り判定時間ｔｂを０．２秒とする。ビット同期信号の検出に０．１秒を要し、ビット同期信号が１秒間送出されるような場合では、信号送出開始後０．５秒経過後に０．１５秒のフェージングがあった場合でも受信は終了せず、フェージング終了後ビット同期検出を再開することにより残り０．３５秒のビット同期信号で検出可能となる。
【００２６】
このように短いノイズを受信した場合には、そのノイズの消滅後の受信動作の早期終了を行い、消費電流の削減が可能になる。またフェージング等のノイズに影響されず受信が継続され、信頼性の向上（道路付近に取り付けられた場合でも通信信頼性の低下を少なくする）が可能となる。
【００２７】
（実施例２）
次に請求項２、請求項４、請求項８の実施例を図５〜６を用いて説明する。図５は本発明の実施例２の検針用無線装置の信号の送受信を説明するためのタイミングチャートであり、図６は信号判定手段の動作を示す流れ図である。構成、および電文の構成は実施例１と同一とし、図１、図２を使用する。実施例１と異なる点は、図６に示す信号判定手段の動作であり、ビット同期検出途上でキャリアが検出されなくなった場合（ｓｔｅｐ５のＮｏ判定）、その時間を通算し積算時間ｔを計測する（ｓｔｅｐ１１）こと、キャリアが検出された場合（ｓｔｅｐ５のＹｅｓ判定）積算時間ｔの計測を中断する（ｓｔｅｐ１６）こと、ビット同期検出途上、単位時間ｔｐを計測、確認し（ｓｔｅｐ１２）、単位時間ｔｐ経過毎に（ｓｔｅｐ１２から１３へ）積算時間ｔがしきい値とする所定の時間（ｔｐｓ）より大であるか小であるかを確認し（ｓｔｅｐ１３）、大であればビット同期信号の受信を中断し（ｓｔｅｐ１３から１０へ）、小であれば計測中の積算時間ｔを初期化する（ｓｔｅｐ１３から１４へ）ところである。なお実施例１と共通のものは同一構造を有し、説明は省略する。
【００２８】
次に信号判定手段の詳細な受信動作について図５のタイミングチャートのタイミングに沿って図６の流れ図を用いて説明する。実施例１と同様に受信手段３３が駆動手段３１により駆動されるとキャリアセンス手段３４がキャリアセンスを行い（ｓｔｅｐ１）、キャリアが検出されなければ受信動作を終了させ（ｓｔｅｐ２から１０へ）、キャリアがあれば（ｓｔｅｐ２から３へ）ビット同期検出のタイムアウト時間Ｔを初期化して計測開始し（ｓｔｅｐ３）、キャリアを確認しながら（ｓｔｅｐ４、５）ビット同期の検出を開始する（ｓｔｅｐ６）。このタイムアウト時間Ｔは実施例１同様にＴｈを基準とする。
【００２９】
今、家庭用機器等の使用やモータ、エンジン等からのイグニッションノイズ等により、短いノイズが多発し、キャリアセンスレベル（Ｅｓ）程度の強度となったとすると、受信タイミング（５ア）から受信を開始し、ビット同期の検出（ｓｔｅｐ６）をおこなうが、パルス性のノイズのため、短い周期で受信強度が変動し、時折キャリアが検出されず積算時間ｔを加算してしまう（ｓｔｅｐ１１）。この状態において単位時間ｔｐが経過すると（ｓｔｅｐ１２から１３へ）、積算時間ｔを確認する（ｓｔｅｐ１３）。この時間ｔは、しきい値ｔｐｓと比較しており、キャリアの検出されない時間がｔｐｓを超えると（５イ）、時間Ｔｈ経過以前でも受信動作を終了させる（ｓｔｅｐ１３から１０へ）。このように短いノイズが群発し、受信強度の十分検出されない時間が短い場合でも、単位時間当たりの積算時間で判定するため受信中止の判断が可能となる。
【００３０】
また、ビット同期検出途上（ｓｔｅｐ４から７ループ処理中）にフェージングを受けた場合には、受信タイミング（５ウ）から受信を開始し、ビット同期の検出を行う（ｓｔｅｐ６）。受信強度が変動し、（５エ）、キャリアが検出されなくなると（ｓｔｅｐ５のＮｏ判定）、時間ｔを積算する（ｓｔｅｐ１１）が、フェージングは頻度が小さいため、単位時間ｔｐ毎の時間ｔの判定（ｓｔｅｐ１３）においてしきい値（ｔｐｓ）を超過することがなく検出途上で誤って受信を終了させる（ｓｔｅｐ１３から１０へ移行する）ことがなくなる。
【００３１】
なお、ｔｐｓの時間は検針用無線装置周囲で発生する可能性のあるノイズについてパルス幅と発生周期とから算出される積算時間以下または検針用無線装置に対し、周囲環境の影響範囲（距離）と影響範囲内を移動する車両等の標準移動時間の最大値以上に定める。例えば実施例１で説明した検針用無線装置と同様の環境を考えるならば、周囲環境の影響範囲（距離）と影響範囲内を移動する車両等の標準移動時間、単位時間当たりの通行頻度を基準に定める。また例えば道路上で影響する範囲が３ｍにわたり、通過する車両の時速を６０ｋｍ／ｈとし、１秒間に４台の通過がある場合には積算して０．７２秒間のフェージングが予め予想される。単位時間を０．５秒とし、積算時間をに０．０２秒の設計余裕を取り判定時間ｔｐｓを０．３８秒とする。ビット同期信号の検出に０．１秒を要し、ビット同期信号が１秒間送出されるような場合では、信号送出開始後０．１秒後と０．３秒経過後に０．１５秒のフェージングがあった場合でも、積算時間は０．３秒となるため受信は終了せず、フェージング終了後ビット同期検出を再開することにより残り０．５５秒のビット同期信号で検出可能となる。また、イグニッションノイズの場合では、エンジン等の回転数により周期は短くなるが、瞬時の着火によるノイズであるため、瞬間的であり、デューティは小さくなる。上記の例でデューティ１／１０とした場合には積算時間が０．５秒の単位時間に対して０．４５秒となるため、受信を中断することとなる。このように、ノイズとフェージングの区別が早期に行え、ノイズ受信時には受信動作の早期終了ができ、消費電流の削減が可能となる。また、フェージングを受けた場合でも終了後受信が可能であるため受信率が向上し、信頼性の向上（フェージングによる誤検出がなく、道路付近に取り付けられた場合でも受信時間の増加を少なくする）が可能となる。
【００３２】
（実施例３）
請求項５、請求項９の実施例を図７〜８を用いて説明する。図７は本発明の実施例２の検針用無線装置の信号の送受信を説明するためのタイミングチャートであり、図８は信号判定手段の動作を示す流れ図である。構成、および電文の構成は実施例１と同一とし、図１、図２を使用する。なお実施例１と共通のものは同一構造を有し、説明は省略する。
【００３３】
次に信号判定手段の詳細な受信動作について図７のタイミングチャートのタイミングに沿って図８の流れ図を用いて説明する。実施例１の要領で受信手段３３が駆動され、ビット同期が検出される（ｓｔｅｐ１）と、フレーム同期検出までのタイムアウト時間Ｔの計測を初期化し（ｓｔｅｐ２）、キャリアを確認しながら（ｓｔｅｐ３、４）フレーム同期の検出を開始する（ｓｔｅｐ６）。今、説明を簡単にするためビット同期が１０１０の連続の信号に対し、フレーム同期信号は“１１００”という４ビットの信号とする。この信号のビット同期信号との符号間距離は２ビットであり、２ビット誤った場合には誤検出の可能性がある。キャリアが正常に入力されている場合にはキャリア検出不良となる時間ｔの計測を随時初期化再スタートしながら（ｓｔｅｐ５）フレーム同期の検出を待ち（ｓｔｅｐ７）、フレーム同期が確定した場合には（ｓｔｅｐ７Ｙｅｓ判定）以降の信号を受信し（ｓｔｅｐ８）データ終了により受信を終了する（ｓｔｅｐ９から１０へ）。フレーム同期が確定しない場合には（ｓｔｅｐ７Ｎｏ判定）、タイムアウト時間Ｔがしきい値Ｔｆ経過により受信を終了する（ｓｔｅｐ１２Ｙｅｓ判定によりｓｔｅｐ１０へ）。本実施例ではこのタイムアウト時間Ｔｆはビット同期信号とフレーム同期信号の長さの合計を基準にして定めている。
【００３４】
今、フェージングが発生し、キャリアが一時的（長さｔ３）に検出されなくなった場合（ｓｔｅｐ４のＮｏ判定）、初期化後の経過時間としての時間ｔの確認が行われる（ｓｔｅｐ１１）。この時間ｔは、フレーム同期とビット同期の符号間距離２ビット分の長さｔｃをキャリア検出不能時間のしきい値（判定時間）としており、キャリアの検出されない時間が判定時間ｔｃを超えると（７エ）この間のデータが誤りを起こし、この誤判定の可能性のあるビット数が符号間距離を超えるため判定誤りを起こす恐れがあるが、判定時間が２ビット文の長さｔｃとなっているため、時間Ｔｆ経過以前でも受信動作を終了させる（ｓｔｅｐ１１から１０へ）。これにより、異常なフェージングが発生し、誤判定の可能性のある場合に受信を終了することができるため、誤った位置からフレーム同期を検出し、以降の要求信号の受信誤りがなくなり、誤動作を防止し、通信信頼性の向上に役立つ。なお、通常はフレーム同期位置を誤って判定した場合でも誤動作を起こさないために、以降の信号には各種の誤り制御やデータ確認が行われているため誤動作を起こすことは稀であるが、判断が速くでき、以降の信号を受信する前に受信を中断することが可能となるため消費電流の増加を最小限にとどめることができ、消費電流の低減が可能となる。
【００３５】
（実施例４）
請求項６、請求１０の実施例を図９を用いて説明する。図９は本発明の実施例４の検針用無線装置の信号判定手段の動作を示す流れ図である。構成、および電文の構成は実施例２と同一とし、図１、図２を使用する。なお実施例２と共通のものは同一構造を有し、説明は省略する。
【００３６】
次に信号判定手段の詳細な受信動作について図９の流れ図を用いて説明する。実施例２の要領で受信手段３３が駆動され、ビット同期が検出される（ｓｔｅｐ１）と、フレーム同期検出までのタイムアウト時間Ｔの計測を初期化し（ｓｔｅｐ２）、キャリアの確認を行いながら（ｓｔｅｐ３、４）フレーム同期の検出を開始する（ｓｔｅｐ５）。フレーム同期検出途上でキャリアが検出されなくなった場合（ｓｔｅｐ４のＮｏ判定）、その時間を通算し積算時間ｔを計測し（ｓｔｅｐ１０）、キャリアが検出された場合（ｓｔｅｐ４のＹｅｓ判定）積算時間ｔの計測を中断する（ｓｔｅｐ１６）。今、説明を簡単にするため、フレーム同期信号を３２ビットとし、ビット同期信号との符号間距離は８とする。フレーム同期検出の判定を３ビット誤りまで許容して確定させるとすると、３２ビット中４ビット以上誤ると誤検出の可能性がある。単位時間を３２ビット分の時間（ｔｑ）とし、積算時間ｔのしきい値（所定時間）を４ビット分の時間（ｔｑｎ）とすると、キャリアが正常に入力されている場合（ｓｔｅｐ４Ｙｅｓ判定）にはフレーム同期の検出を待ち（ｓｔｅｐ６）、キャリアが検出されない場合には（ｓｔｅｐ４Ｎｏ判定）積算時間ｔを加算する（ｓｔｅｐ１０）。フレーム同期が確定した場合には（ｓｔｅｐ６Ｙｅｓ判定）以降の信号を受信し（ｓｔｅｐ７）データ終了により受信を終了する（ｓｔｅｐ９）。フレーム同期が確定しない場合には単位時間ｔｑの経過毎に積算時間ｔの確認、初期化を行い（ｓｔｅｐ１１、１２、１３）、積算時間ｔがしきい値ｔｑｎを超えなければ、タイムアウト時間Ｔを確認し（ｓｔｅｐ１４）、しきい値Ｔｆ経過により受信を終了する（ｓｔｅｐ９へ）。
【００３７】
ところで、周囲環境の変化等により、電波環境が悪化した場合、キャリアの検出が不安定となり、散発的な誤りが発生しやすくなる。今、こうした現象が発生したとすると、キャリアの検出が断続的になされなくなり（ｓｔｅｐ４Ｎｏ判定）、積算時間ｔの計測が行われる（ｓｔｅｐ１０）。この積算時間ｔは、前述のフレーム同期判定の誤り許容ビット数以上をしきい値としており、単位時間ｔｑの間でキャリアの検出されない時間がｔｑｎを超えるとフレーム同期が誤判定となる可能性がでるため、時間Ｔｆ経過以前でも受信動作を終了させる（ｓｔｅｐ１２から９へ）。
【００３８】
これにより、電波強度の低下や不安定により、誤判定の可能性のある場合に受信を終了することができるため、誤った位置からフレーム同期を検出し、以降の要求信号の受信誤りがなくなり、誤動作を防止することに役立つ。なお、こうした誤動作を防ぐため、以降の信号には各種の誤り制御やデータ確認が行われているが、この場合でも速い判断で受信を中断することが可能となるため消費電流の増加を最小限にとどめることができる。
【００３９】
【発明の効果】
以上の説明から明らかのように本発明の無線装置によれば次の効果が得られる。
【００４０】
信号判定手段は、無線信号の受信強度が判定値以上となったことにより復調信号の受信を開始し、受信強度が判定値以下となる時間が判定時間以上連続した場合に信号受信を中止するため、短いノイズにより信号受信を中断することがなく、受信強度の異常に対し、早期に異常判定して受信動作を停止するので、受信率が向上する。
【００４１】
また、無線信号の受信強度が判定値以上となったことにより復調信号の信号受信を開始し、受信強度が判定値以下となる時間が単位時間当たり所定の時間以上となった場合に信号受信を中止するため短いノイズが頻繁に発生する等の異常に対し、早期に判定して受信動作を停止することができるので、受信率が向上する。
【００４２】
また、信号判定手段は、無線信号の受信強度が判定値以上となったことにより復調信号のビット同期検出を開始し、受信強度が判定値以下となる時間が判定時間以上連続した場合にビット同期検出を中止するため、受信強度の異常に対し、早期に異常判定して受信動作を停止するとともに、短いノイズによりビット同期検出を中断することなく継続してビット同期検出が行えるため、単発のノイズに対し、繰り返し送出されるビット同期の検出率が向上し、通信信頼性が向上する。
【００４３】
また、無線信号の受信強度が判定値以上となったことにより復調信号のビット同期検出を開始し、受信強度が判定値以下となる時間が単位時間当たり所定の時間以上となった場合にビット同期検出を中止するため、単体の短いノイズでビット同期検出を中断することなく、短いノイズが頻繁に発生する等の異常に対し、早期に判定してビット同期検出を停止することができるので、周期的なノイズに対しても、繰り返し送出されるビット同期の検出率が向上し、通信信頼性が向上する。
【００４４】
また、ビット同期検出完了により復調信号のフレーム同期検出を開始し、受信強度が判定値以下となる時間が判定時間以上連続した場合にフレーム同期検出を中止するため短いノイズによりフレーム同期検出を中断することなく、バースト誤りとなるような長いノイズによるフレーム同期の誤検出の可能性を早期に異常判定してフレーム同期検出動作を停止できるので、バースト誤りに対するフレーム同期の誤検出を防ぎ、通信信頼性が向上する。
【００４５】
また、ビット同期検出完了により復調信号のフレーム同期検出を開始し、受信強度が判定値以下となる時間が単位時間当たり所定の時間以上となった場合にフレーム同期検出を中止するため、単体の短いノイズによりフレーム同期検出を中断することなく、短いノイズが頻繁に発生する等の異常によるフレーム同期検出の誤検出の可能性を早期に異常判定して受信動作を停止することができるので、ランダム誤りに対するフレーム同期の誤検出を防ぎ、通信信頼性が向上する。
【００４６】
また、検針用無線装置において信号判定手段が、無線信号の受信強度が判定値以上となったことにより復調信号のビット同期検出を開始し、受信強度が判定値以下となる時間が判定時間以上連続した場合にビット同期検出を中止するため、短いノイズによりビット同期検出を中断することがなく継続してビット同期検出が行えるため、検針用無線装置周辺で発生しやすいフェージングによる短時間の異常に対し、ビット同期検出の中止を行わないため、ビット同期検出率が向上し、通信の成功率、検針効率が向上する。さらに受信強度の異常に対し、早期に異常判定して受信動作を停止するため、周辺で発生するイグニッションノイズをキャリアセンスし、ビット同期検出を開始しても、早期に異常判定してビット同期検出を中止することができ、こうしたノイズの受信により増加する消費電流が低減し、電池寿命が延長する。
【００４７】
また、検針用無線装置において信号判定手段が受信強度が判定値以上となったことにより受信手段により受信される信号の同期検出を開始し、さらにこの間、受信強度が判定値以下となる時間が単位時間当たり所定の時間以上となった場合にビット同期検出を中止するため、単体の短い電界異常や通行量の多い道路に設置された検針用無線機周辺特有の連続するフェージングによりビット同期検出を中断することがなく、電波の消滅や電波強度の不安定等の異常に対し、早期に判定してビット同期検出を中断することができるためビット同期の検出率を下げることがなくなり、受信信頼性、検針効率が向上するとともに、こうしたノイズの受信により増加する消費電流が低減し、電池寿命が延長する。
【００４８】
また、検針用無線装置において、信号判定手段が受信強度が判定値以上となったことにより受信手段により受信される信号のビット同期検出を開始し、さらにビット同期が検出されるとフレーム同期検出を開始し、さらにこの間受信強度が判定値以下となる時間が判定時間以上連続した場合にフレーム同期検出および駆動手段を介して受信手段の受信動作を中止するため、短い電界異常によりフレーム同期検出を中断することなく、検針用無線装置の設置環境に起こりやすいフェージングである、バースト誤りとなるような長い電界異常によるフレーム同期の誤検出の可能性を早期に異常判定して受信動作を停止できるので、バースト誤り発生時にフレーム同期の誤検出に至ることがなく通信の信頼性向上、特に、フレーム同期位置の誤判定による以降のデータの誤受信、それによる誤動作、誤課金等の危険がなくなるとともに、早期に受信を終了することにより、ノイズの受信によって増加する消費電流が低減し、電池寿命が延長する。
【００４９】
また、検針用無線装置において、信号判定手段が、受信強度が判定値以上となったことにより受信手段により受信される信号のビット同期検出を開始し、さらにビット同期検出完了により復調信号のフレーム同期検出を開始し、さらにこの間、予め定められた単位時間毎に受信強度が判定値以下となる時間を通算し、所定の時間以上となった場合にフレーム同期検出および駆動手段を介して受信手段の受信動作を中止するため、単体の短い電界異常等によってフレーム同期検出を中断することがなく、検針用無線装置のように通行量の多い設置環境に起こりやすい、短い電波異常が頻繁に発生する等の異常によるフレーム同期の誤検出の可能性を早期に異常判定して受信動作を停止することができ、ランダム誤りに対するフレーム同期の誤検出による以降のデータの誤受信、それによる誤動作、誤課金等の危険を防ぎ、通信の信頼性が向上するとともに、ノイズを受信することにより増加する消費電流が低減し、電池寿命が延長する。
【図面の簡単な説明】
【図１】本発明の実施例１の無線装置における検針用無線装置のブロック図
【図２】同装置の動作を説明するためのタイミングチャート
【図３】同装置の動作を説明するための別のタイミングチャート
【図４】同装置の信号判定手段の動作を説明する流れ図
【図５】本発明の実施例２の無線装置における動作を説明するためのタイミングチャート
【図６】同装置の信号判定手段の動作を説明する流れ図
【図７】本発明の実施例３の無線装置における動作を説明するためのタイミングチャート
【図８】同装置の信号判定手段の動作を説明する流れ図
【図９】本発明の実施例４の無線装置における信号判定手段の動作を説明する流れ図
【図１０】従来の無線装置における信号判定手段の動作を説明する流れ図
【符号の説明】
１検針用無線装置
２収集側無線機
３検針側無線機
４メータ
５データ収集装置
３１駆動手段
３２タイマ部
３３受信手段
３４キャリアセンス手段
３５信号判定手段
３６応答手段[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a radio apparatus that exchanges signals using radio signals.
[0002]
[Prior art]
  Conventionally, a wireless device is configured to use signal determination means that starts operation when it is determined that there is a signal based on signal strength or the like, and determines that there is no signal after a predetermined time while detecting a specific signal. Especially for wireless devices for meter reading, this method is applied from the viewpoint of power saving, the signal strength is monitored even after the detection of a specific signal is started, and when the strength drops, the signal judgment that the reception is terminated immediately after judging that there is no carrier Some devices use means, and those using such wireless devices are described in JP-A-8-102684. As shown in the flowchart of FIG. 10 of the signal determination means, this apparatus confirms the radio wave intensity (carrier sense) (step 1), and if no carrier is detected, ends the reception (from step 2 to step 7) and determines that there is a radio wave. If so, the bit synchronization detection is started (from step 2 to 3), and if the detection is completed, the subsequent telegram is received (from step 4 to the loop of 5 and 6), and the reception is terminated by the end of data (from step 6 to 7). . If bit synchronization cannot be detected (No at step 4), the elapse of the specified time Th is determined (step 8). If the specified time Th is exceeded, the reception ends (from step 8 to 7) and the standby state is returned. It was like that.
[0003]
[Problems to be solved by the invention]
  However, in the above-described conventional wireless device, in the case of a system that first determines the presence or absence of a signal and then ends reception only after a lapse of a certain time, if the first signal strength is obtained, whether the signal is another system signal only after the passage of time Therefore, any signal is forced to receive the required time (the above-described conventional example Th), which is wasteful in terms of current consumption. In addition, in the method where the presence / absence of a signal is determined by instantaneous carrier determination and reception is terminated when there is no carrier, erroneous determination is likely to occur due to instantaneous carrier level decrease or noise inclusion in the received intensity signal. There was a problem of a decrease.
[0004]
  In particular, in the wireless device for meter reading, there are two types in which the meter reader manually carries the portable radio device and manually reads the meter using a telephone line, both of which can increase the number of meter readings per hour. Otherwise, labor costs or telephone line usage charges (telephone charges) will increase, and profitability cannot be maintained. For this reason, it is necessary to perform meter reading efficiently in order to ensure the reliability of communication. However, such wireless devices are likely to be installed outdoors, near roads, etc. for use. In addition to noise from devices inside and outside the house, such wireless devices are frequently subjected to ignition noise from passing cars, motorcycles, people, etc. The phenomenon of fading, which makes it easier to shift to the receiving operation by carrier sensing this noise or, on the contrary, is affected by the propagation of radio waves when a vehicle etc. passes around and the radio field intensity temporarily decreases. It is highly possible that the generated radio wave cannot be received and reception is poor. Therefore, the first problem is to improve communication reliability without being affected by such noise.
[0005]
  On the other hand, such a device is generally driven by a completely sealed battery because of restrictions on the installation location and the like, and there is a demand for operation guarantee (maintenance-free) for a long period of time (for example, 10 years when the meter certification expires). If this demand cannot be achieved, replacement work must be carried out at a frequency corresponding to this warranty period for all the doors where the equipment is installed, resulting in increased equipment costs and labor costs due to the replacement work. Become. For this reason, it is necessary to extend the battery life as much as possible and to extend the warranty period. However, if the above-mentioned miscellaneous noise or ignition noise is received, current consumption due to the receiving operation increases according to the frequency. When there is a large amount of vehicle traffic, such as near a main road, it occurs frequently and consumes a large amount of current. Even under such conditions, the warranty period for all devices is the worst condition. As a result, the warranty period is shortened, and the above-mentioned problem appears remarkably. In addition, in a place where the radio wave environment is good, it is exchanged more frequently than necessary, which is wasteful. The second problem is to reduce the increase in reception time due to uncertain elements such as noise, thereby reducing the increase in current and making it constant regardless of conditions.
[0006]
[Means for Solving the Problems]
  In order to solve the above problems, the present invention performs reception strength confirmation after signal reception starts and measurement of the time during which the level below the judgment value continues, and if the level below the judgment value continues for more than the judgment time The reception of the signal is stopped.
[0007]
  According to the above invention, it is possible to detect a change in radio wave intensity that occurs after the start of signal reception and to stop the signal reception process.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
  The wireless device of the present invention starts receiving a demodulated signal when the reception strength of the radio signal is equal to or higher than the determination value, and stops receiving the signal when the time when the reception strength is equal to or lower than the determination value continues for the determination time or longer. To do. As a result, the reception is not erroneously terminated due to a short noise, and it is possible to determine the abnormality early and stop the reception operation with respect to the abnormality in the reception intensity, and the reception reliability can be improved.
[0009]
  In addition, reception of the demodulated signal is started when the reception strength of the radio signal is equal to or higher than the determination value, and signal reception is stopped when the time when the reception strength is equal to or lower than the determination value exceeds a predetermined time per unit time. To do. As a result, it is possible to make an early determination and stop the reception operation for an abnormality such as frequent occurrence of short noise, and the reception reliability can be improved.
[0010]
  Also, the bit synchronization detection of the demodulated signal is started when the reception strength of the radio signal is higher than the judgment value, and the bit synchronization detection is stopped when the time when the reception strength is lower than the judgment value continues for more than the judgment time It is. As a result, the bit synchronization detection is not interrupted by a short noise, and the reception operation is stopped by making an abnormality determination at an early stage with respect to an abnormality in reception intensity, so that the reception rate is improved. In particular, in bit synchronization detection, it is common that a sufficient bit synchronization length is secured to attempt bit synchronization detection multiple times. Therefore, reception reliability is ensured by not interrupting reception even after the occurrence of reception strength or higher. Great improvement effect.
[0011]
  Also, bit synchronization detection of the demodulated signal is started when the reception strength of the radio signal is equal to or higher than the judgment value, and bit synchronization is performed when the time when the reception strength is lower than the judgment value is equal to or higher than a predetermined time per unit time The detection is stopped. As a result, it is possible to make an early determination and stop the reception operation for an abnormality such as frequent occurrence of short noise, and it is possible to reduce current consumption that is increased by receiving noise. In particular, in bit synchronization detection, it is common that a sufficient bit synchronization length is secured to attempt bit synchronization detection multiple times. Therefore, reception reliability is ensured by not interrupting reception even after the occurrence of reception strength or higher. Great improvement effect.
[0012]
  Also, the frame synchronization detection of the demodulated signal is started upon completion of the bit synchronization detection, and the frame synchronization detection is stopped when the time when the reception intensity is equal to or lower than the determination value continues for the determination time or longer. This makes it possible to detect the possibility of burst errors due to long noise without interrupting frame synchronization detection due to short noise, and to determine the possibility of erroneous detection of frame synchronization early and stop the reception operation. Will improve.
[0013]
  Also, the frame synchronization detection of the demodulated signal is started upon completion of the bit synchronization detection, and the frame synchronization detection is stopped when the time when the reception intensity is equal to or lower than the determination value becomes equal to or longer than a predetermined time per unit time. This enables early detection of the possibility of random errors due to abnormalities such as frequent occurrence of such noise without interrupting frame synchronization detection due to short noise, and early determination of the possibility of erroneous detection of frame synchronization detection. As a result, the reception operation can be stopped, and the reliability is improved.
[0014]
  In addition, it transmits a data request signal with a header signal including a bit synchronization signal, receives a response signal for the signal driven by a battery, collects data, and a meter reading value when the data request signal is received The meter-reading radio is configured to receive a radio signal, a driving means for periodically driving the receiving means, and the intensity of the received signal to a predetermined level. Carrier sensing means for comparison, signal determination means for processing a received signal, and meter reading value response means for responding a meter reading value or the like with a radio signal when a data request signal is received by the signal determining means Is. Then, the driving means drives the receiving means, the carrier sensing means measures the intensity of the received signal, and the signal determining means determines the signal received by the receiving means when the received intensity is equal to or higher than the determination value. Bit synchronization detection is started, and when the time during which the reception intensity is equal to or less than the determination value continues for a determination time or longer, the reception operation of the reception unit can be stopped via the bit synchronization detection and driving unit. As a result, bit synchronization detection is not interrupted by short noise such as fading, improving the success rate of communication, and detecting noise early in response to abnormal reception strength and stopping the reception operation. As a result, the increased current consumption is reduced and the battery life is extended.
[0015]
  Further, the driving means drives the receiving means, the carrier sensing means measures the strength of the received signal, and the signal determining means determines the signal received by the receiving means when the received intensity is equal to or higher than the determination value. Bit synchronization detection is started, and during this time, predeterminedunitSumming up the time when the reception intensity is below the judgment value every time, and stopping the reception operation of the receiving means via the bit synchronization detection and driving means when it exceeds the predetermined time, so the reception is interrupted due to short noise Without receiving, the reception can be stopped when the average reception level cannot be sufficiently obtained due to abnormal occurrence of fading. As a result, it is possible to make an early determination and stop the reception operation for abnormalities such as the average reception level not being sufficient due to abnormalities in the radio wave environment, etc., so there is no risk of erroneous determination or malfunction, and the reception rate is improved. At the same time, the current consumption that increases due to the reception of noise is reduced and the battery life is extended.
[0016]
  The driving means drives the receiving means, the carrier sensing means measures the intensity of the received signal, and the signal determining means is a bit of the signal received by the receiving means when the received intensity is equal to or higher than the determination value. Synchronization detection is started, and when bit synchronization is detected, frame synchronization detection is started. Further, when the time during which the reception intensity is equal to or lower than the determination value continues for the determination time or longer, reception is performed via the frame synchronization detection and driving means. Since the reception operation of the means is stopped, the reception can be interrupted due to a change in the radio wave intensity during reception. Therefore, without interrupting the frame synchronization detection due to short noise, it is possible to stop the reception operation by determining the possibility of burst error and the possibility of erroneous detection of frame synchronization at an early stage, thereby improving communication reliability and malfunctioning. Etc. can be eliminated. In addition, current consumption that increases due to the reception of noise is reduced, leading to an extension of battery life.
[0017]
  The driving means drives the receiving means, the carrier sensing means measures the intensity of the received signal, and the signal determining means is a bit of the signal received by the receiving means when the received intensity is equal to or higher than the determination value. Synchronization detection is started, and further, frame synchronization detection of the demodulated signal is started upon completion of bit synchronization detection.unitThe total reception time of the reception means is stopped by the frame synchronization detection and drive means when the reception intensity is less than the judgment value every time, and when it exceeds the predetermined time, the average reception level is sufficiently high. The reception can be canceled if there is no. For this reason, it is necessary to determine the possibility of random errors due to abnormalities such as frequent occurrence of short noises with insufficient average reception levels and the possibility of erroneous detection of frame synchronization detection at an early stage, and stop the reception operation. Thus, communication reliability is improved, and current consumption that is increased by receiving noise can be reduced.
[0018]
  Embodiments of a wireless device according to the present invention will be described below with reference to the drawings.
[0019]
  Example 1
Embodiments of claims 1, 3, and 7 will be described with reference to FIGS.1 is a block diagram of a wireless device for meter reading in a wireless device according to a first embodiment of the present invention. 2 and 3 are timing charts for explaining signal transmission / reception, and FIG. 4 is a flowchart showing the operation of the signal determination means.
[0020]
  In FIG. 1, reference numeral 1 denotes a meter-reading radio device, which includes a collecting-side radio device 2 and a meter-reading-side radio device 3. Reference numeral 4 denotes a meter, and the meter reading value of the meter 4 is collected by the data collecting device 5 via the meter-reading wireless device 1. The collecting-side radio 2 transmits a data request signal including a header, the meter-reading-side radio 3 includes a battery 37 as a power source, and the timer unit 32 creates a timing for intermittent reception and is driven according to the timing. The means 31 sets the receiving means 33 in a receiving state where the radio signal can be demodulated. 34 of the received radio waveReceiveMeasure the intensity and compare it to a predetermined level (Es)To determine the presence or absence of a carrierIt is a carrier sense means. Reference numeral 35 denotes a signal determination unit. When the receiving unit 33 is ready to be received by the driving unit 31 and a carrier is detected by the carrier sensing unit 34, the demodulated signal from the receiving unit 33 is analyzed, and bit synchronization detection, frame Synchronous detection and request signal reception. Reference numeral 36 denotes response means. When the request signal is confirmed by the signal determination means 35, the meter reading value data from the meter 4 is sent to the collecting-side radio 2 as a response signal. The collection-side wireless device 2 receives this response signal and stores the meter reading data in the data collection device 5.
[0021]
  FIG. 2 is a timing chart for explaining the transmission / reception operation of the present embodiment, in which a header signal c including a bit synchronization signal a and a frame synchronization signal b is repeated as a packet configuration of a signal transmitted from the collection-side radio 2. A post-data request signal d is added.
[0022]
  Next, the detailed reception operation of the signal determination means will be described with reference to the flowchart of FIG. 4 along the timing charts of FIGS. In order to suppress current consumption, the driving unit 31 drives the receiving unit 33 at a sampling period (Ts) corresponding to the signal length from the collecting-side radio 2. When the receiving means 33 is driven, the carrier sensing means 34 performs carrier sensing (step 1). If no carrier is detected, the receiving operation is terminated (from step 1 to 11), and if there is a carrier (Yes in step 2), a timeout time is reached. Initialize T and start measurement (step 3), while checking the carrier (steps 4 and 5), if there is a carrierThis is the time when the received strength is below the judgment valueMeasuring time tInitialize and start measuring(Step 6), bit synchronization is detected (step 7). The above operation is continued while checking the elapse of time T (step 13) until bit synchronization is detected (steps 4 to 8, 13 loop). The timeout time T is determined based on the header signal configuration, and the header length Th is used as a reference in this embodiment.
[0023]
  Now, when a signal from another system or a short-time noise (length t1) is received, reception is started from the reception timing (3a) and bit synchronization is detected (step 7), but the noise ends (3 B) When no carrier is detected (from step 5 to 12)As the elapsed time after initializationMeasurement of time t proceeds. This time t is a threshold value tb based on the time required for radio wave fluctuation due to fading or the like.(Judgment time)If the time during which no carrier is detected exceeds tb (3 c), the reception operation is terminated even before the time Th has elapsed (from step 12 to step 11). As a result, it is possible to terminate the reception of ignition noise having a short duration or noise from the device at an early stage.
[0024]
  Also, in the operation when fading at time t2 is received during the bit synchronization detection, the carrier is detected from the reception timing (3d) (from step 2 to 3, 4, 5, 6), and reception is started. Detection is performed (step 7). Here, when fading occurs (3) and no carrier is detected (from step 5 to 12), the measurement of time t is started, but since fading ends at t2 (<tb), determination of time t In (step 12), it does not exceed (from step 12 to 4), the carrier is detected as time t2 elapses, and the bit synchronization detection is performed again (from step 5 to 6), so that reception can be performed safely.
[0025]
  The time tb is determined based on the influence range (distance) of the surrounding environment and the standard movement time of a vehicle or the like moving within the influence range with respect to the meter-reading wireless device. For example, when the influence range on the road is 3 m and the speed of the passing vehicle is 60 km / h, since fading of 0.18 seconds is predicted in advance, a design margin of 0.02 seconds is taken and the determination time tb Is 0.2 seconds. In the case where 0.1 second is required for detection of the bit synchronization signal and the bit synchronization signal is transmitted for 1 second, even if fading of 0.15 second occurs after 0.5 seconds have elapsed since the signal transmission started. Is not ended, and detection of the remaining bit synchronization signal of 0.35 seconds becomes possible by resuming bit synchronization detection after fading is completed.
[0026]
  When such short noise is received, the reception operation after the disappearance of the noise is terminated early, and current consumption can be reduced. Further, reception is continued without being affected by noise such as fading, and reliability can be improved (decrease in communication reliability is reduced even when installed near a road).
[0027]
  (Example 2)
Next, embodiments of claims 2, 4 and 8 will be described with reference to FIGS.FIG. 5 is a timing chart for explaining signal transmission / reception of the meter-reading radio apparatus according to the second embodiment of the present invention, and FIG. 6 is a flowchart showing the operation of the signal determination means. The configuration and the configuration of the message are the same as those in the first embodiment, and FIGS. 1 and 2 are used. The difference from the first embodiment is the operation of the signal determination means shown in FIG. 6, and when a carrier is not detected during bit synchronization detection (No determination in step 5),Total timeMeasure the accumulated time t (step 11)The carrier If it is issued (Yes at step 5), the measurement of the accumulated time t is interrupted (step 16).In the course of bit synchronization detection, the unit time tp is measured and confirmed (step 12), and the integrated time t is increased every time the unit time tp elapses (from step 12 to step 13).Specified time as thresholdIt is confirmed whether it is larger or smaller than (tps) (step 13). If larger, reception of the bit synchronization signal is interrupted (from step 13 to 10). (Step 13 to 14). In addition, the thing common to Example 1 has the same structure, and description is abbreviate | omitted.
[0028]
  Next, the detailed receiving operation of the signal determining means will be described with reference to the flowchart of FIG. 6 along the timing of the timing chart of FIG. As in the first embodiment, when the receiving means 33 is driven by the driving means 31, the carrier sensing means 34 performs carrier sensing (step 1), and if no carrier is detected, the receiving operation is terminated (from step 2 to step 10). If there is (from step 2 to 3), the bit synchronization detection timeout time T is initialized and measurement is started (step 3), and bit synchronization detection is started (step 6) while checking the carrier (step 4 and 5). This timeout time T is based on Th as in the first embodiment.
[0029]
  Now, assuming that short noise occurs frequently due to the use of household appliances, ignition noise from motors, engines, etc., and the intensity is about the carrier sense level (Es), reception starts from the reception timing (5A) However, detection of bit synchronization (step 6) is performed, but due to pulse noise, the reception intensity fluctuates in a short cycle, and sometimes the carrier is not detected and the integration time t is added (step 11). In this state, when the unit time tp elapses (from step 12 to step 13), the integration time t is confirmed (step 13). This time t is compared with the threshold value tps. When the time during which no carrier is detected exceeds tps (5a), the reception operation is ended even before the time Th has elapsed (from step 13 to step 10). Even when short noise swarms and the time when the reception intensity is not sufficiently detected is short, it is possible to determine whether to stop reception because the determination is based on the integrated time per unit time.
[0030]
  Further, when fading is received during the bit synchronization detection (during 7 loop processing from step 4), reception is started from the reception timing (5) and bit synchronization is detected (step 6). When the reception intensity fluctuates (5 d) and no carrier is detected (No determination at step 5), the time t is integrated (step 11). However, since fading is less frequent, determination of the time t per unit time tp In (step 13), the threshold value (tps) is not exceeded, and reception is not erroneously terminated (shifted from step 13 to 10) during detection.
[0031]
  Note that the tps time is equal to or less than the accumulated time calculated from the pulse width and generation period for noise that may occur around the meter-reading wireless device or the influence range (distance) of the surrounding environment with respect to the meter-reading wireless device. It is set to be equal to or greater than the maximum standard travel time for vehicles moving within the range of influence. For example, if an environment similar to the wireless device for meter reading described in the first embodiment is considered, the influence range (distance) of the surrounding environment, the standard movement time of the vehicle moving within the influence range, and the traffic frequency per unit time are used as a reference. Stipulated in Further, for example, when the range of influence on the road is 3 m, the speed of the passing vehicle is 60 km / h, and there are four passes in one second, a total of 0.72 seconds of fading is predicted in advance. The unit time is 0.5 seconds, the design time is taken as 0.08 seconds, and the judgment time tps is 0.38 seconds. In the case where 0.1 second is required for detection of the bit synchronization signal and the bit synchronization signal is transmitted for 1 second, 0.15 second fading is performed after 0.1 second and 0.3 second from the start of signal transmission. Even if there is, the integration time is 0.3 seconds, so the reception is not terminated, and the bit synchronization signal of the remaining 0.55 seconds can be detected by restarting the bit synchronization detection after the fading is completed. In the case of ignition noise, the cycle is shortened depending on the rotational speed of the engine or the like, but since it is noise due to instantaneous ignition, it is instantaneous and the duty is reduced. In the above example, when the duty is 1/10, the integration time is 0.45 seconds with respect to a unit time of 0.5 seconds, so reception is interrupted. Thus, noise and fading can be distinguished at an early stage, and when a noise is received, the reception operation can be terminated early, and current consumption can be reduced. In addition, even after fading, it is possible to receive after completion, so the reception rate is improved and reliability is improved (there is no false detection due to fading, and the increase in reception time is reduced even when installed near the road) Is possible.
[0032]
  (Example 3)
Embodiments of claims 5 and 9 will be described with reference to FIGS.FIG. 7 is a timing chart for explaining signal transmission / reception of the meter-reading radio apparatus according to the second embodiment of the present invention, and FIG. 8 is a flowchart showing the operation of the signal determination means. The configuration and the configuration of the message are the same as those in the first embodiment, and FIGS. 1 and 2 are used. In addition, the thing common to Example 1 has the same structure, and description is abbreviate | omitted.
[0033]
  Next, the detailed reception operation of the signal determination means will be described with reference to the flowchart of FIG. 8 along the timing chart of FIG. When the receiving unit 33 is driven and bit synchronization is detected (step 1) in the manner of the first embodiment, the measurement of the timeout time T until frame synchronization detection is initialized (step 2), and the carrier is confirmed (steps 3 and 4). ) Detection of frame synchronization is started (step 6). For the sake of simplicity, it is assumed that the frame synchronization signal is a 4-bit signal “1100” with respect to a continuous signal with 1010 bit synchronization. The inter-code distance between this signal and the bit synchronization signal is 2 bits, and if 2 bits are wrong, there is a possibility of erroneous detection. When the carrier is input normally, the measurement of the time t when the carrier detection is defective is initialized at any time.restartWhile (step 5) waits for detection of frame synchronization (step 7), and when frame synchronization is confirmed (step 7 Yes determination), a signal after step (step 8) is received and the reception is terminated when the data ends (from step 9 to step 10). When the frame synchronization is not fixed (step 7 No determination), the reception ends when the timeout time T reaches the threshold value Tf (step 12 Yes determination returns to step 10). In this embodiment, the timeout time Tf is determined based on the total length of the bit synchronization signal and the frame synchronization signal.
[0034]
  Now, when fading occurs and the carrier is temporarily not detected (length t3) (No determination in step 4),After initializationelapsed timeConfirmation of time t asIs performed (step 11). This time t is a threshold t of a carrier detection impossible time, which is a length tc corresponding to a 2-bit distance between codes of frame synchronization and bit synchronization.(Judgment time)The time when no carrier is detectedJudgment timeIf tc is exceeded (7 d), the data during this time causes an error, and the number of bits that may be erroneously determined exceeds the inter-code distance.errorHowever, since the determination time is the length tc of the 2-bit sentence, the reception operation is terminated even before the time Tf has elapsed (from step 11 to step 10). As a result, abnormal fading occurs, and reception can be terminated when there is a possibility of erroneous determination.Therefore, frame synchronization is detected from an incorrect position, and there is no reception error of subsequent request signals, resulting in malfunction. To prevent and improve communication reliability. Normally, even if the frame synchronization position is mistakenly determined, malfunction does not occur, so it is rare to cause malfunction because various error control and data confirmation are performed on the subsequent signals. And the reception can be interrupted before the subsequent signal is received, so that the increase in current consumption can be minimized and the current consumption can be reduced.
[0035]
  Example 4
Embodiments of claims 6 and 10 will be described with reference to FIG.FIG. 9 is a flowchart showing the operation of the signal determination means of the wireless device for meter reading according to the fourth embodiment of the present invention. Configuration and message configuration are examples21 and FIG. 2 are used. Examples2And those having the same structure have the same structure, and description thereof is omitted.
[0036]
  Next, the detailed reception operation of the signal determination means will be described with reference to the flowchart of FIG. Example2When the receiving means 33 is driven and bit synchronization is detected (step 1), the measurement of the timeout time T until frame synchronization detection is initialized (step 2), and the carrier is confirmed (steps 3 and 4). Detection of synchronization is started (step 5).When no carrier is detected in the middle of frame synchronization detection (No determination at step 4), the total time t is measured (step 10), and when a carrier is detected (Yes determination at step 4), the integration time t The measurement is interrupted (step 16).For simplicity of explanation, the frame synchronization signal is 32 bits, and the intersymbol distance from the bit synchronization signal is 8. If the determination of frame synchronization detection is allowed and confirmed up to a 3-bit error, there is a possibility of erroneous detection if there is an error of 4 bits or more out of 32 bits. The unit time is 32 bits (tq).Integration time tThreshold(Predetermined time)Is a 4-bit time (tqn), the frame synchronization detection is awaited when the carrier is normally input (step 4 Yes determination) (step 6), and the integration time when the carrier is not detected (step 4 No determination). t is added (step 10). When frame synchronization is confirmed (Step6Yes judgment) Receive subsequent signals (step7) Reception ends when data ends (step9). When frame synchronization is not fixed, the accumulated time t is checked and initialized every time the unit time tq elapses (steps 11, 12, and 13). If the accumulated time t does not exceed the threshold value tqn, the timeout time T is set. Confirmation (step 14), and the reception ends when the threshold value Tf elapses (to step 9).
[0037]
  By the way, when the radio wave environment deteriorates due to changes in the surrounding environment, carrier detection becomes unstable and sporadic errors are likely to occur. Now, assuming that such a phenomenon occurs, carrier detection is not intermittently performed (step 4 No determination).TotalTime t is measured (step 10). thisTotalThe time t has a threshold value equal to or greater than the number of allowable error bits in the frame synchronization determination described above, and frame synchronization may be erroneously determined if the time during which no carrier is detected during the unit time tq exceeds tqn. Even before the elapse of time Tf, the receiving operation is terminated (from step 12 to step 9).
[0038]
  As a result, reception can be terminated when there is a possibility of erroneous determination due to a decrease or instability in radio field strength, so that frame synchronization is detected from an incorrect position, and subsequent request signal reception errors are eliminated. Helps prevent malfunctions. In order to prevent such malfunctions, various error control and data confirmation are performed for the subsequent signals. However, even in this case, reception can be interrupted with a quick judgment, so that an increase in current consumption is minimized. It can be kept in.
[0039]
【The invention's effect】
  As is clear from the above description, the wireless device of the present invention provides the following effects.
[0040]
  The signal determination means starts receiving the demodulated signal when the reception strength of the radio signal is equal to or higher than the determination value, and stops signal reception when the time when the reception strength is equal to or lower than the determination value continues for the determination time or longer. The signal reception is not interrupted by a short noise, and the reception operation is stopped by determining the abnormality early in response to the abnormality in the reception intensity, so that the reception rate is improved.
[0041]
  In addition, the reception of the demodulated signal is started when the reception strength of the radio signal is equal to or higher than the determination value. Since the reception operation can be stopped at an early stage with respect to an abnormality such as frequent occurrence of short noise due to the cancellation, the reception rate is improved.
[0042]
  The signal determination means starts bit synchronization detection of the demodulated signal when the reception strength of the radio signal is equal to or higher than the determination value, and performs bit synchronization when the time when the reception strength is equal to or lower than the determination value continues for the determination time or longer. In order to stop detection, abnormal reception is judged early and reception operation is stopped for abnormal reception strength, and bit synchronization detection can be performed continuously without interrupting bit synchronization detection due to short noise. On the other hand, the detection rate of repeatedly transmitted bit synchronization is improved, and the communication reliability is improved.
[0043]
  Also, bit synchronization detection of the demodulated signal is started when the reception strength of the radio signal is equal to or higher than the judgment value, and bit synchronization is performed when the time when the reception strength is lower than the judgment value is equal to or higher than a predetermined time per unit time Because detection is stopped, bit synchronization detection can be stopped early and anomalies such as frequent occurrence of short noise can be stopped without interrupting bit synchronization detection with a single short noise. Even in the case of noise, the detection rate of repeatedly transmitted bit synchronization is improved, and communication reliability is improved.
[0044]
  Also, frame synchronization detection of the demodulated signal is started upon completion of bit synchronization detection, and frame synchronization detection is interrupted due to short noise in order to stop frame synchronization detection when the time when the received intensity is below the determination value continues for the determination time or longer. Therefore, it is possible to stop the frame synchronization detection operation by abnormally determining the possibility of erroneous detection of frame synchronization due to long noise that causes a burst error, thus preventing erroneous detection of frame synchronization for burst errors and communication reliability. Will improve.
[0045]
  In addition, the frame synchronization detection of the demodulated signal is started upon completion of the bit synchronization detection, and the frame synchronization detection is stopped when the time when the reception intensity is equal to or less than the determination value is equal to or more than a predetermined time per unit time. Random errors can be made because it is possible to determine the possibility of erroneous detection of frame synchronization detection due to abnormalities such as frequent occurrences of short noise without interrupting frame synchronization detection due to noise, and to stop the reception operation by detecting abnormalities at an early stage. In this way, erroneous detection of frame synchronization is prevented, and communication reliability is improved.
[0046]
  Further, in the wireless device for meter reading, the signal determination unit starts bit synchronization detection of the demodulated signal when the reception strength of the wireless signal is equal to or higher than the determination value, and the time when the reception strength is equal to or lower than the determination value continues for the determination time or longer. In this case, the bit synchronization detection is stopped without interruption, and the bit synchronization detection can be continued without interruption due to a short noise. Since the bit synchronization detection is not stopped, the bit synchronization detection rate is improved, and the communication success rate and meter reading efficiency are improved. Furthermore, in order to stop the reception operation by determining the abnormality at an early stage in response to an abnormality in the reception strength, even if it detects the ignition noise generated in the surroundings and detects the bit synchronization, it detects the abnormality early and detects the bit synchronization. The current consumption that increases due to the reception of such noise is reduced, and the battery life is extended.
[0047]
  In addition, in the wireless device for meter-reading, the signal determination unit starts detecting the synchronization of the signal received by the reception unit when the reception intensity is equal to or higher than the determination value, and during this time, the unit of time during which the reception intensity is lower than the determination value Bit synchronization detection is interrupted by a single short electric field abnormality or continuous fading unique to the area around a meter-reading radio installed on a high-traffic road to stop bit synchronization detection when the time exceeds a predetermined time. Without failing, it is possible to interrupt bit synchronization detection at an early stage for abnormalities such as the disappearance of radio waves or instability of radio field strength, so that the detection rate of bit synchronization is not lowered, and the reception reliability, The meter reading efficiency is improved, the current consumption that increases due to the reception of such noise is reduced, and the battery life is extended.
[0048]
  Further, in the wireless device for meter reading, when the signal determining means starts receiving the bit synchronization of the signal received by the receiving means when the reception intensity becomes equal to or higher than the determination value, and further detects the frame synchronization when the bit synchronization is detected. The frame synchronization detection is interrupted due to a short electric field abnormality in order to stop the reception operation of the reception means via the frame synchronization detection and drive means when the time during which the reception intensity is below the decision value continues for a period longer than the decision time. Without fading, fading is likely to occur in the installation environment of the meter-reading wireless device, because it is possible to stop the reception operation by early abnormality determination of the possibility of erroneous detection of frame synchronization due to a long electric field abnormality resulting in a burst error, Improving communication reliability without erroneous frame synchronization detection when a burst error occurs, especially erroneous determination of frame synchronization position Erroneous reception of subsequent data by, malfunction due to it, with the risk of charging such erroneous is eliminated by terminating the reception early, the current consumption is reduced to increase the received noise, battery life is prolonged.
[0049]
  In the wireless device for meter-reading, the signal determination means starts bit synchronization detection of the signal received by the reception means when the reception intensity is equal to or higher than the determination value, and further, the frame synchronization of the demodulated signal is completed when the bit synchronization detection is completed. Start detection, and during this timeunitThe total time that the reception intensity is below the judgment value for each time is added, and when it exceeds the predetermined time, the reception operation of the reception means is stopped via the frame synchronization detection and drive means, so a single short electric field abnormality etc. Frame synchronization detection is not interrupted by this, and there is an early possibility of erroneous detection of frame synchronization due to abnormalities such as frequent occurrence of short radio wave abnormalities that are likely to occur in installation environments with a large amount of traffic, such as meter-reading radio devices. It is possible to stop the reception operation by judging abnormalities, prevent the risk of subsequent erroneous reception of data due to erroneous detection of frame synchronization for random errors, the resulting malfunction, erroneous billing, etc., and improve communication reliability The current consumption increased by receiving noise is reduced, and the battery life is extended.
[Brief description of the drawings]
FIG. 1 is a block diagram of a wireless device for meter reading in a wireless device according to a first embodiment of the present invention.
FIG. 2 is a timing chart for explaining the operation of the apparatus
FIG. 3 is another timing chart for explaining the operation of the apparatus.
FIG. 4 is a flowchart for explaining the operation of the signal determination unit of the apparatus.
FIG. 5 is a timing chart for explaining the operation of the radio apparatus according to the second embodiment of the present invention.
FIG. 6 is a flowchart for explaining the operation of the signal determination unit of the apparatus.
FIG. 7 is a timing chart for explaining the operation of the wireless device according to the third embodiment of the present invention.
FIG. 8 is a flowchart for explaining the operation of the signal determination unit of the apparatus.
FIG. 9 is a flowchart for explaining the operation of the signal determination unit in the wireless apparatus according to the fourth embodiment of the present invention.
FIG. 10 is a flowchart for explaining the operation of signal determination means in a conventional radio apparatus;
[Explanation of symbols]
  1 Wireless device for meter reading
  2 Collection side radio
  3 Metering side radio
  4 meters
  5 Data collection device
  31 Driving means
  32 Timer section
  33 Receiving means
  34 Career sense means
  35 Signal judging means
  36 Response means

Claims

A signal for starting reception of a demodulated signal when the reception strength of the radio signal is equal to or higher than a determination value, and stopping reception of the demodulated signal when a time when the reception strength is equal to or lower than the determination value continues for a determination time tb or longer. A wireless device having determination means.

When the reception strength of the radio signal is equal to or higher than the determination value, reception of the demodulated signal is started, and the time when the reception strength is equal to or lower than the determination value is equal to or higher than a predetermined time tps per unit time tp. A radio apparatus having a signal determination means for canceling reception of.

A signal that starts bit synchronization detection of a demodulated signal when the reception strength of the radio signal is equal to or higher than the determination value, and stops the bit synchronization detection when the time when the reception strength is equal to or lower than the determination value continues for the determination time tb or longer. A wireless device having determination means.

Bit synchronization detection of the demodulated signal is started when the reception strength of the radio signal is equal to or higher than the determination value, and the time when the reception strength is equal to or lower than the determination value becomes equal to or higher than the predetermined time tps per unit time tp. A radio apparatus having signal determination means for canceling synchronization detection.

A radio apparatus comprising signal determination means for starting frame synchronization detection of a demodulated signal upon completion of bit synchronization detection, and for stopping frame synchronization detection when a time when the reception intensity is equal to or less than a determination value continues for a determination time tc or longer.

The bit synchronization detection completion starts frame synchronization detection of the demodulated signal, having a signal determining means to abort the frame synchronization detection when the time reception intensity is less than the determination value becomes a unit time tq per predetermined time tqn more Wireless device.

Transmits a data request signal with a header signal including a bit synchronization signal, receives a response signal to the signal and collects data, and collects data when the data request signal is received by a battery. The meter-reading-side radio unit is configured to receive a radio signal, a driving unit that periodically drives the receiving unit, and the intensity of the received signal is set to a predetermined value. Carrier sensing means for comparing with a level, signal determining means for processing the received signal, and meter reading value responding means for responding a meter reading value or the like with a radio signal when a data request signal is received by the signal determining means And the signal determination means detects the bit synchronization of the demodulated signal when the reception means is driven by the drive means and the reception intensity of the radio signal is equal to or higher than the determination value. It started, and the wireless device to a standby state the operation of the receiving means time reception intensity is equal to or less than the determination value through the bit synchronization detection and drive means in the case of more than determination time tb.

Transmits a data request signal with a header signal including a bit synchronization signal, receives a response signal to the signal and collects data, and is driven by a battery, and when the data request signal is received, the meter reading value The meter-reading-side radio unit receives a radio signal, a driving unit that periodically drives the receiving unit, and the intensity of the received signal is predetermined. Carrier sensing means for comparing the received signal level, signal determination means for processing the received signal, and meter reading value response means for responding a meter reading value or the like with a radio signal when a data request signal is received by the signal determining means. The signal judging means comprises: the receiving means is driven by the driving means, and the bit synchronization detection of the demodulated signal is detected when the reception strength of the radio signal is equal to or higher than the judgment value. Started, the standby state the operation of the reception means via the bit synchronization detection and drive means when the time reception intensity is less than the determination value is equal to or more than a predetermined time tps a predetermined unit time in tp Wireless device to do.

Transmits a data request signal with a header signal including a bit synchronization signal and a frame synchronization signal, receives a response signal to the signal and collects data, and receives the data request signal driven by a battery Then, it is composed of a meter-reading-side radio that responds with a meter-reading value, etc., and the meter-reading-side radio receives a receiving means for receiving a radio signal, a driving means for periodically driving the receiving means, and the received signal Carrier sense means for comparing the intensity with a predetermined level, signal determination means for processing the received signal, and a meter reading value that responds with a radio signal when a data request signal is received by the signal determination means Response means, and the signal determination means is a demodulated signal when the reception means is driven by the drive means and the reception intensity of the radio signal is equal to or higher than the determination value. Start bit synchronization detection further bit synchronization detection starts to the frame sync detection completion, the receiving reception strength through the frame sync detection and driving means when it becomes less than the determination value or more predetermined judgment time tc A wireless device that sets the operation of the means in a standby state.

Transmits a data request signal with a header signal including a bit synchronization signal and a frame synchronization signal, receives a response signal to the signal and collects data, and receives the data request signal driven by a battery Then, it is composed of a meter-reading-side radio that responds with a meter-reading value, etc., and the meter-reading-side radio receives a receiving means for receiving a radio signal, a driving means for periodically driving the receiving means, and the received signal Carrier sense means for comparing the intensity with a predetermined level, signal determination means for processing the received signal, and a meter reading value that responds with a radio signal when a data request signal is received by the signal determination means Response means, and the signal determination means is a demodulated signal when the reception means is driven by the drive means and the reception intensity of the radio signal is equal to or higher than the determination value. Start bit synchronization detection further bit synchronization detection completion by starts frame synchronization detection of the demodulated signal, the frame synchronous reception strength detection during the pre-unit defined time tq time equal to or less than the determination value is greater than a predetermined time tqn A radio apparatus that puts the operation of the receiving means in a standby state via frame synchronization detection and driving means when it becomes