JP2019174416A - Distance measuring system - Google Patents
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S11/00—Systems for determining distance or velocity not using reflection or reradiation
- G01S11/02—Systems for determining distance or velocity not using reflection or reradiation using radio waves
Abstract
Description
本発明は、２者間の距離を測定する測距システムに関する。 The present invention relates to a distance measuring system that measures a distance between two persons.
従来、２者間で電波を送受信し合って、電波の伝搬時間から２者間の距離を演算する測距システムが周知である（特許文献１等参照）。この測距システムでは、基地局から端末に電波を送信し、その電波を端末から基地局に返信させる。そして、このときの電波のやり取りに要した伝搬時間から、基地局と端末との間の距離を演算する。 2. Description of the Related Art Conventionally, a distance measuring system that transmits and receives radio waves between two parties and calculates the distance between the two parties from the propagation time of the radio waves is well known (see Patent Document 1, etc.). In this distance measuring system, a radio wave is transmitted from a base station to a terminal, and the radio wave is returned from the terminal to the base station. Then, the distance between the base station and the terminal is calculated from the propagation time required for the exchange of radio waves at this time.
ところで、特許文献１の測距システムは、２者間の通信がブルートゥース通信であるとの明記はなく、ブルートゥース通信する２者間の距離を求めたいニーズがある。よって、ブルートゥース通信する２者間の距離を精度よく演算できる技術開発のニーズがあった。 By the way, the ranging system of Patent Document 1 does not specify that the communication between the two parties is Bluetooth communication, and there is a need to obtain the distance between the two parties performing Bluetooth communication. Therefore, there has been a need for technological development that can accurately calculate the distance between two parties communicating via Bluetooth.
本発明の目的は、第１通信機及び第２通信機の間の距離算出の精度を確保可能にした測距システムを提供することにある。 An object of the present invention is to provide a distance measuring system that can ensure the accuracy of distance calculation between a first communication device and a second communication device.
前記問題点を解決する測距システムは、第１通信機及び第２通信機の一方から他方にブルートゥースの通信を通じて電波を送信し、当該電波の伝搬特性を求めて当該伝搬特性を逆フーリエ変換することにより、前記第１通信機及び前記第２通信機の間の距離を演算する構成であって、前記第１通信機及び前記第２通信機の間で送信される電波として、周期的なデジタル符号からなる周期信号を生成する波形生成部と、受信した電波をフーリエ変換することによって求まる周波数スペクトルの伝搬特性において、ＤＣ成分付近の位相を基に当該ＤＣ成分の位相を補間することにより、ＤＣ成分伝搬特性を抽出するＤＣ成分抽出部と、抽出された前記ＤＣ成分伝搬特性を複数周波数分、合成する合成部と、合成により得られた伝搬特性を逆フーリエ変換した演算結果から、前記第１通信機及び前記第２通信機の間の距離を演算する測距部とを備えた。 A ranging system that solves the above problem transmits radio waves from one of the first communication device and the second communication device to the other through Bluetooth communication, obtains propagation characteristics of the radio waves, and performs inverse Fourier transform on the propagation characteristics. Accordingly, the distance between the first communication device and the second communication device is calculated, and a periodic digital signal is transmitted as a radio wave transmitted between the first communication device and the second communication device. By interpolating the phase of the DC component based on the phase in the vicinity of the DC component in the propagation characteristics of the frequency spectrum obtained by Fourier transforming the received radio wave, and the waveform generation unit that generates a periodic signal composed of codes, the DC A DC component extraction unit that extracts component propagation characteristics, a synthesis unit that synthesizes the extracted DC component propagation characteristics for a plurality of frequencies, and an inverse Fourier transform of the propagation characteristics obtained by the synthesis. From the converted operation result, and a distance measuring unit for calculating a distance between said first communication device and the second communication device.
本構成によれば、周期的なデジタル符号からなる周期信号を電波として送信して測距を行うので、伝搬特性として求められる周波数スペクトルが周期的に立つことになる。このため、位相スペクトルのＤＣ成分を補間する場合には、一定周期で立ち上がる周波数スペクトルの傾向を踏まえてＤＣ成分の位相を補間することが可能となるので、ＳＮ（ＳＮ比：信号雑音比）の高いデータのみを使用して、ＤＣ成分の位相を抽出することが可能となる。これにより、逆フーリエ変換の演算結果が精度よく求まる。よって、第１通信機及び第２通信機の間の距離を精度よく求めることが可能となる。 According to this configuration, since a periodic signal composed of a periodic digital code is transmitted as a radio wave and distance measurement is performed, a frequency spectrum required as propagation characteristics stands periodically. For this reason, when the DC component of the phase spectrum is interpolated, it is possible to interpolate the phase of the DC component based on the tendency of the frequency spectrum that rises at a constant period, so that the SN (SN ratio: signal to noise ratio) It is possible to extract the phase of the DC component using only high data. Thereby, the calculation result of the inverse Fourier transform is obtained with high accuracy. Therefore, the distance between the first communication device and the second communication device can be obtained with high accuracy.
前記測距システムにおいて、前記電波は、複数チャネルで送信されることにより複数周波数での送信が実行され、前記測距部は、各チャネルから測定される伝搬特性を基に、第１通信機及び前記第２通信機の間の距離を演算することが好ましい。この構成によれば、電波を複数チャネルで送信するという簡素な通信態様により、複数周波数での電波送信が可能となる。 In the ranging system, the radio waves are transmitted through a plurality of channels by being transmitted through a plurality of channels, and the ranging unit is configured to transmit the first communication device and the first communication device based on the propagation characteristics measured from each channel. It is preferable to calculate a distance between the second communication devices. According to this configuration, radio waves can be transmitted at a plurality of frequencies by a simple communication mode in which radio waves are transmitted through a plurality of channels.
前記測距システムにおいて、前記ＤＣ成分抽出部は、前記伝搬特性として求まる位相スペクトルにおいて、前記ＤＣ成分の前後の位相の平均をとることにより、前記ＤＣ成分の位相を求めることが好ましい。この構成によれば、位相スペクトルのＤＣ成分の前後平均をとるという簡素な処理により、ＤＣ成分の位相を抽出することが可能となる。 In the ranging system, it is preferable that the DC component extraction unit obtains the phase of the DC component by taking an average of phases before and after the DC component in a phase spectrum obtained as the propagation characteristic. According to this configuration, the phase of the DC component can be extracted by a simple process of averaging the DC component of the phase spectrum before and after.
前記測距システムにおいて、前記デジタル符号は、２値化符号であることが好ましい。この構成によれば、「０」及び「１」から構築される簡素なデータ配列の信号から送信電波を生成することが可能となる。 In the distance measuring system, the digital code is preferably a binarized code. According to this configuration, it is possible to generate a transmission radio wave from a simple data array signal constructed from “0” and “1”.
前記測距システムにおいて、前記周期信号は、前記２値化符号の「０」及び「１」の繰り返しの信号であることが好ましい。この構成によれば、「０」，「１」が単に繰り返される簡素なデータ群から周期信号を構築することが可能となる。 In the distance measuring system, it is preferable that the periodic signal is a signal in which the binary code “0” and “1” are repeated. According to this configuration, it is possible to construct a periodic signal from a simple data group in which “0” and “1” are simply repeated.
前記測距システムにおいて、前記周期信号が送信されるにあたり、前記周期信号をＧＦＳＫ変調する変調部を備えることが好ましい。この構成によれば、信号変調の前に周期信号のスペクトルが整形されるので、スペクトル帯域幅や帯域外スペクトラムを低減することが可能となる。よって、隣接チャネルの電力除去が可能となる。 The ranging system preferably includes a modulation unit that performs GFSK modulation on the periodic signal when the periodic signal is transmitted. According to this configuration, since the spectrum of the periodic signal is shaped before the signal modulation, it is possible to reduce the spectrum bandwidth and the out-of-band spectrum. Therefore, it is possible to remove power from adjacent channels.
前記測距システムにおいて、前記第１通信機及び前記第２通信機は、これらの間の距離を演算するにあたって電波を送受し合い、前記測距部は、前記第１通信機から前記第２通信機に電波を送信して求められる伝搬特性と、前記第２通信機から前記第１通信機に電波を送信して求められる伝搬特性とを基に、前記距離を演算することが好ましい。この構成によれば、第１通信機から第２通信機に電波を送信して求まる伝搬特性と、第２通信機から第１通信機に電波を送信して求まる伝搬特性とを乗算するなどの計算を経ることにより、逆符号の位相誤差をキャンセルすることが可能となる。よって、距離演算の精度確保に一層有利となる。 In the distance measuring system, the first communication device and the second communication device transmit and receive radio waves when calculating a distance between them, and the distance measuring unit transmits the second communication from the first communication device. It is preferable to calculate the distance based on propagation characteristics obtained by transmitting radio waves to a machine and propagation characteristics obtained by sending radio waves from the second communication device to the first communication device. According to this configuration, the propagation characteristic obtained by transmitting radio waves from the first communication device to the second communication device is multiplied by the propagation characteristics obtained by transmitting radio waves from the second communication device to the first communication device, etc. Through the calculation, it is possible to cancel the phase error of the opposite sign. Therefore, it becomes more advantageous for ensuring the accuracy of the distance calculation.
本発明によれば、第１通信機及び第２通信機の間の距離算出の精度を確保することができる。 According to the present invention, it is possible to ensure the accuracy of distance calculation between the first communication device and the second communication device.
以下、測距システムの一実施形態を図１〜図９に従って説明する。
図１に示すように、測距システム１は、無線通信を行う第１通信機２及び第２通信機３の間の距離Ｌを測定する。本例の測距システム１は、無線によって接続された第１通信機２及び第２通信機３の間で電波Ｓｉを複数チャネルに亘り送受し、これら各チャネルにおいて伝搬特性（振幅及び位相）を求める。そして、求めた複数チャネルの伝搬特性を合成し、合成により得られた伝搬特性を逆フーリエ変換することにより、等価的にインパルスの伝搬時間Ｔｘ、すなわち距離Ｌを演算する。本例の場合、例えば第１通信機２が車両の電子キーであり、例えば第２通信機３が車両である。第１通信機２及び第２通信機３の通信は、例えばブルートゥース（Bluetooth：登録商標）であることが好ましい。
Hereinafter, an embodiment of a distance measuring system will be described with reference to FIGS.
As shown in FIG. 1, the ranging system 1 measures a distance L between a first communication device 2 and a second communication device 3 that perform wireless communication. The distance measuring system 1 of this example transmits and receives radio waves Si across a plurality of channels between the first communication device 2 and the second communication device 3 that are connected by radio, and the propagation characteristics (amplitude and phase) in each of these channels. Ask. Then, by combining the obtained propagation characteristics of a plurality of channels and performing inverse Fourier transform on the propagation characteristics obtained by the synthesis, an impulse propagation time Tx, that is, a distance L is calculated equivalently. In this example, for example, the first communication device 2 is an electronic key of a vehicle, and the second communication device 3 is a vehicle, for example. The communication between the first communication device 2 and the second communication device 3 is preferably, for example, Bluetooth (registered trademark).
図２に示すように、測距システム１は、電波Ｓｉの送信側となる電波送信部６と、電波Ｓｉの受信側となる電波受信部７とを備える。電波送信部６は、波形生成部８、変調部９、ＤＡコンバータ１０、ミキサ１１、発振器１２及び送信アンテナ１３を備える。 As shown in FIG. 2, the distance measuring system 1 includes a radio wave transmission unit 6 on the radio wave Si transmission side and a radio wave reception unit 7 on the radio wave Si reception side. The radio wave transmission unit 6 includes a waveform generation unit 8, a modulation unit 9, a DA converter 10, a mixer 11, an oscillator 12, and a transmission antenna 13.
波形生成部８は、第１通信機２及び第２通信機３の間で送信される電波Ｓｉとして、周期的な２値化符号からなる周期信号Ｓｋを生成し、これを変調部９に出力する。周期信号Ｓｋは、２値化符号の「０」及び「１」が周期Ｔごとに切り替わる信号である。変調部９は、ＧＦＳＫ（Gaussian Frequency Shift Keying）からなる。周期信号Ｓｋは、変調部９で変調されて、ＤＡコンバータ１０でＤ／Ａ変換された後、ミキサ１１で発振器１２の搬送波と重畳されて、送信アンテナ１３から送信される。 The waveform generation unit 8 generates a periodic signal Sk composed of a periodic binarized code as the radio wave Si transmitted between the first communication device 2 and the second communication device 3, and outputs this to the modulation unit 9 To do. The periodic signal Sk is a signal in which “0” and “1” of the binarized code are switched every period T. The modulation unit 9 is composed of GFSK (Gaussian Frequency Shift Keying). The periodic signal Sk is modulated by the modulator 9, D / A converted by the DA converter 10, superposed on the carrier wave of the oscillator 12 by the mixer 11, and transmitted from the transmission antenna 13.
電波受信部７は、受信アンテナ１６、ミキサ１７、発振器１８、ＡＤコンバータ１９及びフーリエ変換部２０を備える。電波受信部７は、電波送信部６から送信された周期信号Ｓｋの電波Ｓｉを受信アンテナ１６で受信すると、受信信号をミキサ１７でベースバンド信号Ｓｂに変換し、これをＡＤコンバータ１９でＡ／Ｄ変換する。そして、Ａ／Ｄ変換後の信号がフーリエ変換部２０によって変換（ＦＦＴ変換）されることにより、受信信号の周波数スペクトル（伝搬特性）が測定される。伝搬特性は、送受信された電波Ｓｉの振幅及び位相の各データである。 The radio wave receiving unit 7 includes a receiving antenna 16, a mixer 17, an oscillator 18, an AD converter 19, and a Fourier transform unit 20. When the radio wave reception unit 7 receives the radio wave Si of the periodic signal Sk transmitted from the radio wave transmission unit 6 by the reception antenna 16, the radio wave reception unit 7 converts the reception signal into the baseband signal Sb by the mixer 17, and this is converted to the A / A by the AD converter 19. D-convert. Then, the signal after A / D conversion is converted (FFT conversion) by the Fourier transform unit 20, whereby the frequency spectrum (propagation characteristic) of the received signal is measured. The propagation characteristics are each amplitude and phase data of the transmitted and received radio wave Si.
測距システム１は、通信時の伝搬特性の測定を、通信されるチャネルの全てで実行する。通信がブルートゥースの場合、複数のチャネル（例えば４０チャネル）が存在するので、全てのチャネル（ＣＨ１，ＣＨ２，…，ＣＨｎ）において伝搬特性の測定が実行される。このように、本例の場合、電波Ｓｉを複数チャネルで送信することにより、電波Ｓｉを複数周波数で送信する。また、本例の場合、第１通信機２から第２通信機３に電波Ｓｉを送信して伝搬特性を測定するとともに、第２通信機３から第１通信機２にも電波Ｓｉを送信して伝搬特性を測定する。すなわち、第１通信機２及び第２通信機３の両方で伝搬特性の測定を行う。この場合、第１通信機２及び第２通信機３の両方に、電波送信部６及び電波受信部７が各々設けられることになる。 The ranging system 1 performs the measurement of the propagation characteristics during communication on all the channels to be communicated. When the communication is Bluetooth, there are a plurality of channels (for example, 40 channels), and therefore propagation characteristics are measured in all channels (CH1, CH2,..., CHn). Thus, in this example, the radio wave Si is transmitted at a plurality of frequencies by transmitting the radio wave Si through a plurality of channels. In the case of this example, the radio wave Si is transmitted from the first communication device 2 to the second communication device 3 to measure the propagation characteristics, and the radio wave Si is also transmitted from the second communication device 3 to the first communication device 2. To measure the propagation characteristics. That is, the propagation characteristics are measured by both the first communication device 2 and the second communication device 3. In this case, both the first communication device 2 and the second communication device 3 are provided with the radio wave transmission unit 6 and the radio wave reception unit 7, respectively.
電波受信部７は、伝搬特性のＤＣ成分を抽出するＤＣ成分抽出部２１を備える。ＤＣ成分抽出部２１は、伝搬特性として振幅及び位相のＤＣ成分（ＤＣ成分伝搬特性）を抽出する。特に、本例のＤＣ成分抽出部２１は、受信した電波Ｓｉをフーリエ変換することによって求まる周波数スペクトルの伝搬特性において、ＤＣ成分付近の位相を基にＤＣ成分の位相を補間して、ＤＣ成分伝搬特性を算出する。ＤＣ成分は、フーリエ変換後（ＦＦＴ変換後）の周波数スペクトルにおいて周波数が「０」のときの特性値である。 The radio wave receiver 7 includes a DC component extractor 21 that extracts a DC component of propagation characteristics. The DC component extraction unit 21 extracts amplitude and phase DC components (DC component propagation characteristics) as propagation characteristics. In particular, the DC component extraction unit 21 of this example interpolates the phase of the DC component based on the phase near the DC component in the propagation characteristics of the frequency spectrum obtained by Fourier transform of the received radio wave Si, and propagates the DC component. Calculate the characteristics. The DC component is a characteristic value when the frequency is “0” in the frequency spectrum after Fourier transform (after FFT transform).
図３に示すように、測距システム１は、乗算部２３、合成部２４、逆フーリエ変換部２５及び測距部２６を備える。なお、乗算部２３、合成部２４、逆フーリエ変換部２５及び測距部２６の機能群は、第１通信機２及び第２通信機３のどちらに設けられていてもよい。 As shown in FIG. 3, the ranging system 1 includes a multiplying unit 23, a combining unit 24, an inverse Fourier transform unit 25, and a ranging unit 26. Note that the function group of the multiplication unit 23, the synthesis unit 24, the inverse Fourier transform unit 25, and the distance measurement unit 26 may be provided in any of the first communication device 2 and the second communication device 3.
乗算部２３は、第１通信機２から第２通信機３に電波送信して測定された伝搬特性と、第２通信機３から第１通信機２に電波送信して測定された伝搬特性とを乗算する。このように、本例の乗算部２３は、第１通信機２から第２通信機３に電波送信して求まったＦＦＴ結果と、第２通信機３から第１通信機２に電波送信して求まったＦＦＴ結果とを乗算する。 The multiplication unit 23 has propagation characteristics measured by transmitting radio waves from the first communication device 2 to the second communication device 3, and propagation characteristics measured by transmitting radio waves from the second communication device 3 to the first communication device 2. Multiply As described above, the multiplication unit 23 of this example transmits the radio wave from the first communication device 2 to the second communication device 3 and transmits the radio wave from the second communication device 3 to the first communication device 2. Multiply the obtained FFT result.
合成部２４は、抽出されたＤＣ成分伝搬特性を複数チャネル分合成する。本例の合成部２４は、各チャネルの伝搬特性を並べたベクトルからなる周波数データＨ（ｆ）を求める。 The synthesizer 24 synthesizes the extracted DC component propagation characteristics for a plurality of channels. The synthesizing unit 24 in this example obtains frequency data H (f) including a vector in which the propagation characteristics of each channel are arranged.
逆フーリエ変換部２５は、合成後の伝搬特性を逆フーリエ変換するものである。逆フーリエ変換部２５は、合成部２４により求められた周波数データＨ（ｆ）を逆フーリエ変換し、その演算結果として時間データｙ（ｔ）を求める。 The inverse Fourier transform unit 25 performs inverse Fourier transform on the combined propagation characteristics. The inverse Fourier transform unit 25 performs inverse Fourier transform on the frequency data H (f) obtained by the synthesis unit 24, and obtains time data y (t) as a calculation result.
測距部２６は、合成により得られた伝搬特性を逆フーリエ変換した演算結果（逆フーリエ変換部２５の演算結果）から、第１通信機２及び第２通信機３の間の距離Ｌを算出する。本例の測距部２６は、逆フーリエ変換部２５により求められた時間データｙ（ｔ）から、第１通信機２及び第２通信機３の間の距離Ｌを算出する。 The distance measuring unit 26 calculates the distance L between the first communication device 2 and the second communication device 3 from the calculation result obtained by performing inverse Fourier transform on the propagation characteristics obtained by the synthesis (calculation result of the inverse Fourier transform unit 25). To do. The distance measuring unit 26 of this example calculates the distance L between the first communication device 2 and the second communication device 3 from the time data y (t) obtained by the inverse Fourier transform unit 25.
次に、図４〜図９を用いて、本実施例の測距システム１の作用及び効果を説明する。
図４に示すように、ステップ１０１において、第１通信機２は、電波Ｓｉを第２通信機３に送信して、第２通信機３に伝搬特性を測定させる。本例の場合、まず波形生成部８は、「０」及び「１」が周期的に繰り返される周期信号Ｓｋを生成し、これを変調部９に出力する。変調部９は、「０」及び「１」の繰り返し信号の周期信号ＳｋをＧＦＳＫ変調し、これをＤＡコンバータ１０に出力する。ＤＡコンバータ１０は、変調後の信号をＤ／Ａ変換する。ＤＡコンバータ１０でＤ／Ａ変換された信号は、ミキサ１１で搬送波に乗せられ、送信アンテナ１３から電波Ｓｉとして送信される。なお、電波Ｓｉが複数チャネルで送信される場合、各チャネルの電波Ｓｉは、各々対応するキャリアに乗せられて送信される。
Next, operations and effects of the distance measuring system 1 according to the present embodiment will be described with reference to FIGS.
As shown in FIG. 4, in step 101, the first communication device 2 transmits the radio wave Si to the second communication device 3 to cause the second communication device 3 to measure the propagation characteristics. In the case of this example, the waveform generation unit 8 first generates a periodic signal Sk in which “0” and “1” are periodically repeated, and outputs this to the modulation unit 9. The modulation unit 9 performs GFSK modulation on the periodic signal Sk of the repetitive signals “0” and “1”, and outputs this to the DA converter 10. The DA converter 10 D / A converts the modulated signal. The signal D / A converted by the DA converter 10 is put on a carrier wave by the mixer 11 and transmitted from the transmission antenna 13 as radio wave Si. When the radio wave Si is transmitted through a plurality of channels, the radio wave Si of each channel is transmitted on a corresponding carrier.
第２通信機３は、第１通信機２から送信された電波Ｓｉを受信アンテナ１６で受信する。受信アンテナ１６で受信した信号は、ミキサ１７を通じてベースバンド信号Ｓｂに変換する。ベースバンド信号Ｓｂは、ＡＤコンバータ１９によってＡ／Ｄ変換され、フーリエ変換部２０に出力される。フーリエ変換部２０は、Ａ／Ｄ変換後の信号をフーリエ変換し、ベースバンド信号Ｓｂの周波数スペクトル（伝搬特性）を測定する。そして、以降、ベースバンド信号ＳｂのＤＣ成分伝搬特性を求めていき、この伝搬特性に基づき、電波受信部７が受信した信号の中心周波数の伝搬特性を測定することができる。 The second communication device 3 receives the radio wave Si transmitted from the first communication device 2 by the reception antenna 16. A signal received by the receiving antenna 16 is converted into a baseband signal Sb through the mixer 17. The baseband signal Sb is A / D converted by the AD converter 19 and output to the Fourier transform unit 20. The Fourier transform unit 20 performs Fourier transform on the signal after A / D conversion, and measures the frequency spectrum (propagation characteristic) of the baseband signal Sb. Thereafter, the DC component propagation characteristic of the baseband signal Sb is obtained, and based on this propagation characteristic, the propagation characteristic of the center frequency of the signal received by the radio wave receiver 7 can be measured.
図５及び図６に示すように、伝搬特性は、周波数スペクトルの要素として振幅データＰ（ｆ）（図５参照）と位相データ∠θ（ｆ）（図６参照）とから構築される。振幅データＰ（ｆ）は、図５に示すようなパワースペクトルで表される。本例の場合、周期Ｔで「０」，「１」が繰り返される周期信号Ｓｋを送信して測距するので、パワースペクトルは、１／Ｔ周期でスペクトルが立つ波形をとる。すなわち、パワースペクトルは、ＤＣ成分である周波数「０」を頂点とした放物線に沿って値が変化する波形をとる。ＤＣ成分抽出部２１は、フーリエ変換後のパワースペクトルからＤＣ成分（周波数「０」）の振幅Ｐ０を抽出する。 As shown in FIGS. 5 and 6, the propagation characteristics are constructed from amplitude data P (f) (see FIG. 5) and phase data ∠θ (f) (see FIG. 6) as frequency spectrum elements. The amplitude data P (f) is represented by a power spectrum as shown in FIG. In the case of this example, since the periodic signal Sk in which “0” and “1” are repeated in the period T is transmitted and the distance is measured, the power spectrum takes a waveform in which the spectrum stands in the 1 / T period. That is, the power spectrum has a waveform whose value changes along a parabola with the frequency component “0” being a DC component at the top. The DC component extraction unit 21 extracts the amplitude P0 of the DC component (frequency “0”) from the power spectrum after the Fourier transform.
図６に示すように、位相データ∠θ（ｆ）は、同図に示すような位相スペクトルで表される。本例の場合、周期Ｔで「０」，「１」が繰り返される周期信号Ｓｋを送信して測距するので、位相スペクトルは、１／Ｔ周期でスペクトルが立つ波形をとる。ここで、図６（ａ）に示すように、例えばベースバンド信号Ｓｂの伝搬による位相変化特性は、値が比例増加していくような直線状をとる。ところで、電波送受信時、Ａ／Ｄ変換やＤ／Ａ変換のサンプリングタイミングの際に遅延が生じるが、仮に遅延が発生した場合には、図６（ｂ）に示すように、位相変化特性の傾きは変化するものの、ＤＣ成分である周波数「０」の位相は変化しない。このように、周波数「０」の位相には遅延の誤差が現れないので、この位相を電波（送信チャネルの中心周波数）の位相として抽出すれば、遅延の誤差をキャンセルできることが分かる。しかし、図６（ｃ）に示すように、実際のところ、周波数「０」の成分にはオフセットによる誤差が生じ、正しく「０」成分を抽出することができない。このように、測距にＤＣ成分の伝搬特性のみ使用するのは、ＤＣ成分の位相には誤差がのらないが、それ以外の成分には誤差が入っているため、使えないからである。 As shown in FIG. 6, the phase data ∠θ (f) is represented by a phase spectrum as shown in FIG. In the case of this example, since the periodic signal Sk in which “0” and “1” are repeated in the period T is transmitted and the distance is measured, the phase spectrum takes a waveform in which the spectrum stands in the 1 / T period. Here, as shown in FIG. 6A, for example, the phase change characteristic due to the propagation of the baseband signal Sb is linear so that the value increases proportionally. By the way, a delay occurs at the time of A / D conversion or D / A conversion sampling timing during radio wave transmission / reception. If a delay occurs, the slope of the phase change characteristic as shown in FIG. Changes, but the phase of the frequency “0”, which is a DC component, does not change. As described above, since a delay error does not appear in the phase of the frequency “0”, it is understood that the delay error can be canceled by extracting this phase as the phase of the radio wave (the center frequency of the transmission channel). However, as shown in FIG. 6C, an error due to an offset occurs in the component of frequency “0”, and the “0” component cannot be correctly extracted. The reason why only the DC component propagation characteristic is used for distance measurement is that there is no error in the phase of the DC component, but there is an error in the other components, and therefore it cannot be used.
そこで、図７に示すように、本例のＤＣ成分抽出部２１は、位相スペクトルのＤＣ成分（周波数「０」）の直近前後の位相θｍ，θｐを利用して、ＤＣ成分の位相θ０を算出する。本例の場合、ＤＣ成分（周波数「０」）の１つ前の位相スペクトルの位相θｍと、ＤＣ成分（周波数「０」）の１つ後の位相スペクトルの位相θｐとの平均を求め、これをＤＣ成分の位相θ０（＝（θｍ＋θｐ）／２）として割り出す。このようにして、本例のＤＣ成分抽出部２１は、周波数スペクトルの伝搬特性において、ＤＣ成分付近の位相を基にＤＣ成分の位相を補間することにより、ＤＣ成分伝搬特性を抽出する。そして、ＤＣ成分抽出部２１は、パワースペクトルのＤＣ成分と、補間により求めた位相スペクトルのＤＣ成分とを、ＤＣ成分伝搬特性として算出する。 Therefore, as shown in FIG. 7, the DC component extraction unit 21 of this example calculates the phase θ0 of the DC component using the phases θm and θp immediately before and after the DC component (frequency “0”) of the phase spectrum. To do. In this example, the average of the phase θm of the phase spectrum immediately before the DC component (frequency “0”) and the phase θp of the phase spectrum immediately after the DC component (frequency “0”) is obtained. Is determined as the phase θ0 (= (θm + θp) / 2) of the DC component. In this manner, the DC component extraction unit 21 of this example extracts the DC component propagation characteristic by interpolating the phase of the DC component based on the phase near the DC component in the propagation characteristic of the frequency spectrum. Then, the DC component extraction unit 21 calculates the DC component of the power spectrum and the DC component of the phase spectrum obtained by interpolation as DC component propagation characteristics.
このように、本例の場合、伝搬特性を測定するにあたり、２値化符号の「０」、「１」が周期Ｔの間隔で繰り返された周期信号Ｓｋを基に生成された電波Ｓｉを送信するので、伝搬特性として求められた周波数スペクトル（パワースペクトル及び位相スペクトル）においては、スペクトル成分が１／Ｔ間隔で周期的に立つことになる。このため、ＤＣ成分の位相θ０を補間するにあたっては、例えばＤＣ成分の前後の位相θｍ，θｐの２値の平均をとるという演算を通じて、位相θ０を抽出することが可能となる。このため、ＳＮ（ＳＮ比：信号雑音比）の高いデータのみ使用することが可能となるので、位相θ０がばらつきの少ない精度のよい値となる。 Thus, in the case of this example, when measuring the propagation characteristics, the radio wave Si generated based on the periodic signal Sk in which the binary codes “0” and “1” are repeated at intervals of the period T is transmitted. Therefore, in the frequency spectrum (power spectrum and phase spectrum) obtained as the propagation characteristics, the spectrum components stand periodically at 1 / T intervals. For this reason, when interpolating the phase θ0 of the DC component, it is possible to extract the phase θ0 through, for example, an arithmetic operation of averaging the binary values θm and θp before and after the DC component. For this reason, only data having a high SN (SN ratio: signal noise ratio) can be used, and the phase θ0 is a highly accurate value with little variation.
図４に戻り、ステップ１０２において、第２通信機３は、電波Ｓｉを第１通信機２に送信して、第１通信機２に伝搬特性（振幅及び位相）を測定させる。すなわち、第２通信機３から第１通信機２に電波Ｓｉを送信して、第１通信機２においても伝搬特性（振幅及び位相）を測定する。なお、伝搬特性の測定は、第１通信機２から第２通信機３に電波送信して行う場合と同様であるので、説明を省略する。 Returning to FIG. 4, in step 102, the second communication device 3 transmits the radio wave Si to the first communication device 2 to cause the first communication device 2 to measure the propagation characteristics (amplitude and phase). That is, the radio wave Si is transmitted from the second communication device 3 to the first communication device 2, and the propagation characteristics (amplitude and phase) are also measured in the first communication device 2. Note that the measurement of the propagation characteristics is the same as that performed when radio waves are transmitted from the first communication device 2 to the second communication device 3, and thus description thereof is omitted.
第１通信機２及び第２通信機３の通信の往復で伝搬特性が各々測定されると、乗算部２３は、第１通信機２から第２通信機３に電波送信して測定された伝搬特性（ＦＦＴ結果）と、第２通信機３から第１通信機２に電波送信して測定された伝搬特性（ＦＦＴ結果）とを乗算する。これにより、測距システム１の各デバイスにクロック誤差やＰＬＬの初期位相誤差が発生していても、これら誤差は送信側と受信側とで逆符号の位相誤差で現れていることから、ＦＦＴ結果の乗算により、これら誤差がキャンセルされる。 When the propagation characteristics are measured in the round trip of communication between the first communication device 2 and the second communication device 3, the multiplication unit 23 transmits the radio wave from the first communication device 2 to the second communication device 3, and the propagation measured. The characteristic (FFT result) is multiplied by the propagation characteristic (FFT result) measured by transmitting a radio wave from the second communication device 3 to the first communication device 2. As a result, even if a clock error or an initial phase error of the PLL occurs in each device of the distance measuring system 1, these errors appear as phase errors of opposite signs on the transmission side and the reception side. These errors are canceled by multiplying.
ここで、図８に示すように、例えばチャネルＣＨ１の電波が通信された場合には、ＣＨ１の中心周波数ｆ１の伝搬特性Ｈ（ｆ１）、すなわちＣＨ１のベースバンド信号ＳｂのＤＣ成分伝搬特性が得られる。伝搬特性Ｈ（ｆ１）は、大きさが振幅特性、位相角が位相特性を表す複素数として得られる。伝搬特性Ｈ１（ｆ１）は、次式(1)により表される。なお、次式では、Ｐ（ｆ１）がＣＨ１の振幅データであり、∠θ（ｆ１）が位相データである。 Here, as shown in FIG. 8, for example, when radio waves of channel CH1 are communicated, the propagation characteristic H (f1) of the center frequency f1 of CH1, that is, the DC component propagation characteristic of the baseband signal Sb of CH1 is obtained. It is done. The propagation characteristic H (f1) is obtained as a complex number whose magnitude represents the amplitude characteristic and whose phase angle represents the phase characteristic. The propagation characteristic H1 (f1) is expressed by the following equation (1). In the following equation, P (f1) is the amplitude data of CH1, and ∠θ (f1) is the phase data.
Ｈ（ｆ１）＝Ｐ（ｆ１）∠θ（ｆ１） … (1)
図４に戻り、ステップ１０３において、測距システム１（第１通信機２及び第２通信機３）は、通信の各チャネルで、順次、伝搬特性を測定する。通信がブルートゥースの場合、複数のチャネル（例えば４０チャネル）が存在するので、各チャネルの全てにおいて通信（往復）の伝搬特性が測定される。このため、例えばＣＨ２〜ＣＨｎの電波が送受信された場合には、各チャネルの中心周波数ｆ２〜ｆｎの各伝搬特性Ｈ（ｆ２）〜Ｈ（ｆｎ）が得られる。複数周波数の伝搬特性を測定するのは、１つの周波数の伝搬特性ではインパルスを作ることができないからである。
H (f1) = P (f1) ∠θ (f1) (1)
Returning to FIG. 4, in step 103, the ranging system 1 (the first communication device 2 and the second communication device 3) sequentially measures the propagation characteristics in each channel of communication. When the communication is Bluetooth, there are a plurality of channels (for example, 40 channels), so the propagation characteristics of communication (round trip) are measured in all of the channels. Therefore, for example, when radio waves of CH2 to CHn are transmitted and received, the propagation characteristics H (f2) to H (fn) of the center frequencies f2 to fn of each channel are obtained. The reason why the propagation characteristics of a plurality of frequencies are measured is that an impulse cannot be created with the propagation characteristics of one frequency.
ステップ１０４において、合成部２４は、全チャネルの往復の伝搬特性を合成する。本例の場合、合成部２４は、各チャネルの伝搬特性を並べたベクトルを作る。本例では、各チャネルの伝搬特性を並べたベクトル、すなわち周波数データＨ（ｆ）として、［Ｈ（ｆ１），Ｈ（ｆ２），…，Ｈ（ｆｎ）］を得る。 In step 104, the combining unit 24 combines the round-trip propagation characteristics of all channels. In this example, the synthesis unit 24 creates a vector in which the propagation characteristics of each channel are arranged. In this example, [H (f1), H (f2),..., H (fn)] is obtained as a vector in which the propagation characteristics of each channel are arranged, that is, frequency data H (f).
ステップ１０５において、逆フーリエ変換部２５は、合成後の伝搬特性（周波数データＨ（ｆ））を逆フーリエ変換する。本例の場合、ベクトル（周波数データＨ（ｆ））を入力データとして、これを逆フーリエ変換し、その演算結果を取得する。逆フーリエ変換の演算結果は、時間データｙ（ｔ）として取得することができる。時間データｙ（ｔ）は、［ｙ（ｔ１），ｙ（ｔ２），…，ｙ（ｔｎ）］で表される。なお、ｔ１〜ｔｎは、各伝搬特性Ｈ（ｆ１）〜Ｈ（ｆｎ）に対応した時間データである。 In step 105, the inverse Fourier transform unit 25 performs inverse Fourier transform on the combined propagation characteristics (frequency data H (f)). In the case of this example, a vector (frequency data H (f)) is used as input data, and this is subjected to inverse Fourier transform to obtain the calculation result. The calculation result of the inverse Fourier transform can be acquired as time data y (t). The time data y (t) is represented by [y (t1), y (t2), ..., y (tn)]. Note that t1 to tn are time data corresponding to the propagation characteristics H (f1) to H (fn).
図９に示すように、測距部２６は、逆フーリエ変換の演算結果を基に、電波Ｓｉの伝搬時間Ｔｘ、すなわち第１通信機２及び第２通信機３の距離Ｌを演算する。逆フーリエ変換を演算すると、同図に示すようなパルス３０を取得できる。なお、マルチパスの影響により複数のパルス３０が出現した場合には、最短時間のもの（パルス３０ａ）を対象パルスとして取得する。測距部２６は、パルス３０ａの位置から伝搬時間Ｔｘを算出し、これを距離Ｌに換算する。 As shown in FIG. 9, the distance measuring unit 26 calculates the propagation time Tx of the radio wave Si, that is, the distance L between the first communication device 2 and the second communication device 3 based on the calculation result of the inverse Fourier transform. When inverse Fourier transform is calculated, a pulse 30 as shown in the figure can be obtained. If a plurality of pulses 30 appear due to the influence of multipath, the pulse having the shortest time (pulse 30a) is acquired as the target pulse. The distance measuring unit 26 calculates the propagation time Tx from the position of the pulse 30a and converts this to the distance L.
なお、パルス３０の選択は、最短時間のものを選ぶ方式に限定されない。例えば、パルス３０のピーク値が最も高いものを対象パルスとして取得してもよい。このように、パルス３０の選択の仕方は、様々な方法が採用できる。 The selection of the pulse 30 is not limited to the method of selecting the pulse with the shortest time. For example, the pulse 30 having the highest peak value may be acquired as the target pulse. As described above, various methods can be employed for selecting the pulse 30.
ところで、例えば周期信号Ｓｋとして２値化符号の「０」，「１」がランダムに並んだビット信号を送信して測距を行う場合、周波数スペクトル（位相スペクトル）がランダムに帯域全体に広がる。このため、ＤＣ成分の位相θ０を補間しようとした場合、例えばスペクトル全体を平均してＤＣ成分の位相θ０を抽出することになるが、この場合はランダムに立ち上がる多数データの平均をとって値を抽出する演算を行うので、精度よい値を求めることができず、ＳＮＲが劣化してしまう。このため、ＳＮが低い部分の位相データも使うことになってしまうので、測距の精度が確保できない問題が生じる。 By the way, for example, when ranging is performed by transmitting a bit signal in which binary codes “0” and “1” are randomly arranged as the periodic signal Sk, the frequency spectrum (phase spectrum) randomly spreads over the entire band. For this reason, when the phase θ0 of the DC component is to be interpolated, for example, the entire spectrum is averaged to extract the phase θ0 of the DC component. In this case, the value is obtained by taking the average of a large number of data rising at random. Since the extraction operation is performed, an accurate value cannot be obtained, and the SNR deteriorates. For this reason, the phase data of a portion having a low SN is also used, which causes a problem that the accuracy of distance measurement cannot be ensured.
一方、本例の場合、周期的な２値化符号からなる周期信号Ｓｋを電波として送信して測距を行うので、伝搬特性として求められる周波数スペクトルが周期的に立つことになる。このため、位相スペクトルのＤＣ成分を補間する場合には、一定周期で立ち上がる周波数スペクトルの傾向を踏まえてＤＣ成分の位相θ０を補間することが可能となるので、ＳＮの高いデータのみを使用して、ＤＣ成分の位相θ０を抽出することが可能となる。特に、本例の場合、ＤＣ成分の前後の位相θｍ，θｐの単なる平均を求めればよい。これにより、逆フーリエ変換の演算結果が精度よく求まる。よって、第１通信機２及び第２通信機３の間の距離Ｌを精度よく求めることができる。 On the other hand, in the case of this example, the periodic signal Sk composed of a periodic binarized code is transmitted as a radio wave to perform distance measurement, so that a frequency spectrum required as a propagation characteristic stands periodically. For this reason, when interpolating the DC component of the phase spectrum, it is possible to interpolate the phase θ0 of the DC component based on the tendency of the frequency spectrum that rises at a constant period, so only data with a high SN is used. The phase θ0 of the DC component can be extracted. In particular, in the case of this example, a simple average of the phases θm and θp before and after the DC component may be obtained. Thereby, the calculation result of the inverse Fourier transform is obtained with high accuracy. Therefore, the distance L between the first communication device 2 and the second communication device 3 can be obtained with high accuracy.
電波Ｓｉは、複数チャネルで送信されることにより複数周波数での送信が実行される。測距部２６は、各チャネルから測定される伝搬特性を基に、第１通信機２及び第２通信機３の間の距離Ｌを演算する。よって、電波Ｓｉを複数チャネルで送信するという簡素な通信態様により、複数周波数での電波送信を実現することができる。 The radio wave Si is transmitted at a plurality of frequencies by being transmitted at a plurality of channels. The distance measuring unit 26 calculates the distance L between the first communication device 2 and the second communication device 3 based on the propagation characteristics measured from each channel. Therefore, radio transmission at a plurality of frequencies can be realized by a simple communication mode in which the radio wave Si is transmitted through a plurality of channels.
デジタル符号は、２値化符号からなる。よって、「０」及び「１」から構築される簡素なデータ配列の信号から送信電波（電波Ｓｉ）を生成することができる。
周期信号Ｓｋは、２値化符号の「０」及び「１」の繰り返しの信号である。よって、「０」，「１」が単に繰り返される簡素なデータ群から周期信号Ｓｋを構築することができる。
The digital code is composed of a binary code. Therefore, a transmission radio wave (radio wave Si) can be generated from a simple data array signal constructed from “0” and “1”.
The periodic signal Sk is a signal in which “0” and “1” of the binary code are repeated. Therefore, the periodic signal Sk can be constructed from a simple data group in which “0” and “1” are simply repeated.
電波送信部６は、周期信号ＳｋをＧＦＳＫ変調する変調部９を備えた。このため、信号変調の前に周期信号Ｓｋのスペクトルが整形されるので、スペクトル帯域幅や帯域外スペクトラムを低減することが可能となる。よって、隣接チャネルの電力除去が可能となる。 The radio wave transmission unit 6 includes a modulation unit 9 that performs GFSK modulation on the periodic signal Sk. For this reason, since the spectrum of the periodic signal Sk is shaped before signal modulation, it becomes possible to reduce the spectrum bandwidth and the out-of-band spectrum. Therefore, it is possible to remove power from adjacent channels.
第１通信機２及び第２通信機３は、これらの間の距離Ｌを演算するにあたって電波Ｓｉを送受し合う。測距部２６は、第１通信機２から第２通信機３に電波Ｓｉを送信して求められる伝搬特性と、第２通信機３から第１通信機２に電波Ｓｉを送信して求められる伝搬特性とを基に、距離Ｌを演算する。ところで、測距システム１の各デバイスには、クロック誤差やＰＬＬの初期位相誤差が発生するが、これら誤差は送信側と受信側とで逆符号の位相誤差として現れる。このため、第１通信機２→第２通信機３の電波送信で求まる伝搬特性と、第２通信機３→第１通信機２の電波送信で求まる伝搬特性とを乗算するなどの計算を経ることにより、逆符号の位相誤差をキャンセルすることができる。よって、距離演算の精度確保に一層有利となる。 The first communication device 2 and the second communication device 3 transmit and receive the radio wave Si when calculating the distance L between them. The distance measuring unit 26 is obtained by transmitting the radio wave Si from the first communication device 2 to the second communication device 3 and transmitting the radio wave Si from the second communication device 3 to the first communication device 2. The distance L is calculated based on the propagation characteristics. By the way, a clock error and an initial phase error of the PLL are generated in each device of the distance measuring system 1. These errors appear as phase errors of opposite signs on the transmission side and the reception side. For this reason, calculation such as multiplying the propagation characteristic obtained by radio wave transmission of the first communication device 2 → the second communication device 3 and the propagation characteristic obtained by radio wave transmission of the second communication device 3 → the first communication device 2 is performed. As a result, the phase error of the opposite sign can be canceled. Therefore, it becomes more advantageous for ensuring the accuracy of the distance calculation.
第１通信機２及び第２通信機３は、一方から他方に対して複数のチャネルで電波を送信する。測距部２６は、各チャネルにおいて伝搬特性を求めて、これら伝搬特性から距離Ｌを演算する。このため、例えば周波数ホッピング等を通じて、ノイズを避けて通信を実行することが可能となる。よって、通信成立性を確保するのに有利となる。 The first communication device 2 and the second communication device 3 transmit radio waves through a plurality of channels from one to the other. The distance measuring unit 26 obtains propagation characteristics in each channel and calculates a distance L from these propagation characteristics. For this reason, for example, communication can be performed while avoiding noise through frequency hopping or the like. Therefore, it is advantageous to ensure communication establishment.
測距部２６は、複数チャネルでＤＣ成分伝搬特性（振幅データ、位相データ）を求め、これらの伝搬特性を合成し、合成により得られた伝搬特性を逆フーリエ変換して、その演算結果から距離Ｌを演算する。よって、複数チャネルの伝搬特性の合成によって得られるパワースペクトル及び位相スペクトルを逆フーリエ変換した演算結果から、第１通信機２及び第２通信機３の間の距離Ｌを精度よく求めることができる。 The distance measuring unit 26 obtains DC component propagation characteristics (amplitude data and phase data) in a plurality of channels, combines these propagation characteristics, performs inverse Fourier transform on the propagation characteristics obtained by the synthesis, and calculates the distance from the calculation result. L is calculated. Therefore, the distance L between the first communication device 2 and the second communication device 3 can be accurately obtained from the calculation result obtained by performing inverse Fourier transform on the power spectrum and the phase spectrum obtained by combining the propagation characteristics of a plurality of channels.
なお、本実施形態は、以下のように変更して実施することができる。本実施形態及び以下の変更例は、技術的に矛盾しない範囲で互いに組み合わせて実施することができる。
・処理は、全てのチャネルを用いることに限定されず、一部のチャネルのみ使用する態様としてもよい。
In addition, this embodiment can be implemented with the following modifications. The present embodiment and the following modifications can be implemented in combination with each other within a technically consistent range.
The processing is not limited to using all channels, but may be a mode in which only some channels are used.
・周期信号Ｓｋは、「０」，「１」が繰り返される信号に限定されない。例えば、「０」，「０」，「１」のデータ群が繰り返される信号など、２値化符号が周期的に繰り返されるものであれば、「０」，「１」の組み合わせは適宜変更できる。 The periodic signal Sk is not limited to a signal in which “0” and “1” are repeated. For example, the combination of “0” and “1” can be appropriately changed as long as the binarized code is periodically repeated, such as a signal in which a data group of “0”, “0”, and “1” is repeated. .
・周期信号Ｓｋは、「０」，「１」の周期的な信号に限定されず、例えば「０」のみ、或いは「１」のみの信号でもよい。
・演算の順序は、フーリエ変換、ＤＣ成分抽出、乗算の順に限定されない。例えば、フーリエ変換、乗算、ＤＣ成分抽出の順序に変更してもよい。
The periodic signal Sk is not limited to a periodic signal of “0” and “1”, and may be a signal of only “0” or “1”, for example.
The order of operations is not limited to the order of Fourier transform, DC component extraction, and multiplication. For example, the order may be changed to Fourier transform, multiplication, and DC component extraction.
・ＤＣ成分の位相θ０は、ＤＣ成分の前後の平均をとった値に限定されない。例えば、ＤＣ成分前後に限らず位相をいくつか抽出し、それらの値からＤＣ成分の位相θ０を求めてもよい。 The phase θ0 of the DC component is not limited to a value obtained by taking an average before and after the DC component. For example, not only before and after the DC component, some phases may be extracted, and the DC component phase θ0 may be obtained from these values.
・第２通信機３は、電子キー機能を有する高機能携帯電話でもよい。
・複数周波数での電波送信は、電波Ｓｉを複数チャネルで送信することに限定されない。例えば、電波送信に使用するチャネルは１つでもよい。この場合、例えば送信する電波Ｓｉのベースバンド信号Ｓｂを規定量、周波数シフトしたものをアップコンバートして電波送信する。そして、周波数シフトしないベースバンド信号Ｓｂから測定された伝搬特性と、周波数シフトしたベースバンド信号Ｓｂから測定された伝搬特性とを用いて、測距を実行してもよい。
The second communication device 3 may be a high function mobile phone having an electronic key function.
The radio wave transmission at a plurality of frequencies is not limited to transmitting the radio wave Si through a plurality of channels. For example, one channel may be used for radio wave transmission. In this case, for example, the baseband signal Sb of the radio wave Si to be transmitted is frequency-shifted by up-converting the baseband signal Sb by a prescribed amount and transmitted. Then, ranging may be performed using the propagation characteristics measured from the baseband signal Sb that is not frequency shifted and the propagation characteristics measured from the baseband signal Sb that is frequency shifted.
・例えば、任意の周波数を「０」とし、これを逆フーリエ変換時に周波数データＨ（ｆ）に加えてもよい。例えば、Ｈ（ｆ）＝［Ｈ（ｆ１），Ｈ（ｆ２），Ｈ（ｆ３），…，Ｈ（ｆｎ）］を、Ｈ（ｆ）＝［Ｈ（ｆ１），０，Ｈ（ｆ２），０，Ｈ（ｆ３），０，…，０，Ｈ（ｆｎ）］として逆フーリエ変換してもよい。こうすることで、逆フーリエ変換後の時間データサンプル数を増やすことができる。前述の例の場合、サンプル数は「ｎ」→「２ｎ−１」となる。 For example, an arbitrary frequency may be “0” and may be added to the frequency data H (f) at the time of inverse Fourier transform. For example, H (f) = [H (f1), H (f2), H (f3),..., H (fn)] is changed to H (f) = [H (f1), 0, H (f2), 0, H (f3), 0,..., 0, H (fn)] may be inverse Fourier transformed. By doing so, the number of time data samples after the inverse Fourier transform can be increased. In the case of the above example, the number of samples becomes “n” → “2n−1”.
・電波の周波数は、種々の周波数が採用できる。
・デジタル符号は、２値化符号に限定されず、ＱＰＳＫ（Quadrature Phase Shift Keying）等の変調を用いる場合を想定して、他の符号に変更してもよい。
・ Various frequencies can be used for radio waves.
The digital code is not limited to the binary code, and may be changed to another code on the assumption that modulation such as QPSK (Quadrature Phase Shift Keying) is used.
・変調部９は、ＧＦＳＫに限定されず、単なるＦＳＫなどの他の部材に変更してもよい。
・第１通信機２を車両とし、第２通信機３を電子キーとすることに限定されない。例えば、第１通信機２を無線通信式のパーソナルコンピュータとし、第２通信機３を無線ＬＡＮルータとしてもよい。
The modulation unit 9 is not limited to GFSK, and may be changed to other members such as simple FSK.
The first communication device 2 is not limited to a vehicle and the second communication device 3 is an electronic key. For example, the first communication device 2 may be a wireless communication personal computer, and the second communication device 3 may be a wireless LAN router.
・測距システム１は、電波を送受し合って測距を行うシステムに限定されない。例えば、第１通信機２及び第２通信機３の一方から他方のみに電波を送信して測距を行う単方向としてもよい。また、第１通信機２及び第２通信機３で電波を送受し合い、さらにもう一度、第１通信機２及び第２通信機３の一方から他方に電波を送信した上で、伝搬特性を求めて、２者間の測距を行ってもよい。 The ranging system 1 is not limited to a system that performs distance measurement by transmitting and receiving radio waves. For example, it is good also as a single direction which transmits a radio wave only to the other from one side of the 1st communication apparatus 2 and the 2nd communication apparatus 3, and performs ranging. In addition, the first communication device 2 and the second communication device 3 transmit and receive radio waves, and once again transmit radio waves from one of the first communication device 2 and the second communication device 3 to obtain the propagation characteristics. Then, ranging between the two may be performed.
・測距システム１は、車両用の電子キーの認証を無線で行う電子キーシステムに使用されることに限定されず、種々のシステムや装置に適用してもよい。
・通信方式は、ブルートゥースに限定されず、例えば無線ＬＡＮやＵＷＢ等の他の通信としてもよい。
The ranging system 1 is not limited to being used in an electronic key system that wirelessly authenticates an electronic key for a vehicle, and may be applied to various systems and devices.
-A communication system is not limited to Bluetooth, For example, it is good also as other communications, such as wireless LAN and UWB.
次に、上記実施形態及び変更例ら把握できる技術的思想について記載する。
（イ）第１通信機及び第２通信機の一方から他方にブルートゥースの通信を通じて電波を送信し、当該電波の伝搬特性を求めて当該伝搬特性を逆フーリエ変換することにより、前記第１通信機及び前記第２通信機の間の距離を演算する測距方法であって、前記第１通信機及び前記第２通信機の間で送信される電波として、周期的なデジタル符号からなる周期信号を生成するステップと、受信した電波をフーリエ変換することによって求まる周波数スペクトルの伝搬特性において、ＤＣ成分付近の位相を基に当該ＤＣ成分の位相を補間することにより、ＤＣ成分伝搬特性を抽出するステップと、抽出された前記ＤＣ成分伝搬特性を複数周波数分、合成するステップと、合成により得られた伝搬特性を逆フーリエ変換した演算結果から、前記第１通信機及び前記第２通信機の間の距離を演算するステップとを備えた測距方法。
Next, a technical idea that can be grasped from the above embodiment and modified examples will be described.
(A) By transmitting radio waves from one of the first communication device and the second communication device to the other through Bluetooth communication, obtaining the propagation characteristics of the radio waves, and performing inverse Fourier transform on the propagation characteristics, the first communication apparatus And a distance measuring method for calculating a distance between the second communication devices, wherein a periodic signal composed of a periodic digital code is used as a radio wave transmitted between the first communication device and the second communication device. And generating a DC component propagation characteristic by interpolating the phase of the DC component based on the phase near the DC component in the propagation characteristic of the frequency spectrum obtained by Fourier transforming the received radio wave. A step of combining the extracted DC component propagation characteristics for a plurality of frequencies, and a calculation result obtained by performing inverse Fourier transform on the propagation characteristics obtained by the combination, Ranging method comprising the step of calculating the distance between the signal device and the second communication device.
１…測距システム、２…第１通信機、３…第２通信機、８…波形生成部、９…変調部、２１…ＤＣ成分抽出部、２４…合成部、２６…測距部、Ｓｉ…電波、Ｓｋ…周期信号、Ｔｘ…伝搬時間、Ｌ…距離、θ０…位相、θｍ…位相、θｐ…位相。 DESCRIPTION OF SYMBOLS 1 ... Ranging system, 2 ... 1st communication apparatus, 3 ... 2nd communication apparatus, 8 ... Waveform production | generation part, 9 ... Modulation part, 21 ... DC component extraction part, 24 ... Synthesis | combination part, 26 ... Ranging part, Si ... Radio wave, Sk ... periodic signal, Tx ... propagation time, L ... distance, .theta.0 ... phase, .theta.m ... phase, .theta.p ... phase.
Claims (7)
前記第１通信機及び前記第２通信機の間で送信される電波として、周期的なデジタル符号からなる周期信号を生成する波形生成部と、
受信した電波をフーリエ変換することによって求まる周波数スペクトルの伝搬特性において、ＤＣ成分付近の位相を基に当該ＤＣ成分の位相を補間することにより、ＤＣ成分伝搬特性を抽出するＤＣ成分抽出部と、
抽出された前記ＤＣ成分伝搬特性を複数周波数分、合成する合成部と、
合成により得られた伝搬特性を逆フーリエ変換した演算結果から、前記第１通信機及び前記第２通信機の間の距離を演算する測距部と
を備えた測距システム。 By transmitting radio waves from one of the first communication device and the second communication device to the other through Bluetooth communication, obtaining the propagation characteristics of the radio waves, and performing inverse Fourier transform on the propagation characteristics, the first communication device and the first communication device A distance measuring system for calculating a distance between two communication devices,
As a radio wave transmitted between the first communication device and the second communication device, a waveform generation unit that generates a periodic signal composed of a periodic digital code,
A DC component extraction unit that extracts the DC component propagation characteristic by interpolating the phase of the DC component based on the phase in the vicinity of the DC component in the propagation characteristic of the frequency spectrum obtained by Fourier transforming the received radio wave;
A combining unit that combines the extracted DC component propagation characteristics for a plurality of frequencies;
A distance measuring system comprising: a distance measuring unit that calculates a distance between the first communication device and the second communication device from a calculation result obtained by performing inverse Fourier transform on the propagation characteristics obtained by combining.
前記測距部は、各チャネルから測定される伝搬特性を基に、第１通信機及び前記第２通信機の間の距離を演算する
請求項１に記載の測距システム。 The radio wave is transmitted through a plurality of frequencies by being transmitted through a plurality of channels,
The distance measuring system according to claim 1, wherein the distance measuring unit calculates a distance between the first communication device and the second communication device based on propagation characteristics measured from each channel.
請求項１又は２に記載の測距システム。 The ranging system according to claim 1, wherein the DC component extraction unit obtains a phase of the DC component by taking an average of phases before and after the DC component in a phase spectrum obtained as the propagation characteristic.
請求項１〜３のうちいずれか一項に記載の測距システム。 The ranging system according to claim 1, wherein the digital code is a binarized code.
請求項４に記載の測距システム。 The distance measuring system according to claim 4, wherein the periodic signal is a signal in which the binarized code is “0” and “1”.
請求項１〜５のうちいずれか一項に記載の測距システム。 The ranging system according to any one of claims 1 to 5, further comprising a modulation unit that performs GFSK modulation on the periodic signal when the periodic signal is transmitted.
前記測距部は、前記第１通信機から前記第２通信機に電波を送信して求められる伝搬特性と、前記第２通信機から前記第１通信機に電波を送信して求められる伝搬特性とを基に、前記距離を演算する
請求項１〜６のうちいずれか一項に記載の測距システム。 The first communication device and the second communication device transmit and receive radio waves in calculating the distance between them,
The distance measuring unit is a propagation characteristic obtained by transmitting radio waves from the first communication device to the second communication device, and a propagation characteristic obtained by transmitting radio waves from the second communication device to the first communication device. The distance measuring system according to any one of claims 1 to 6, wherein the distance is calculated based on the following.
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