Ranging device and ranging method

Abstract

To improve ranging accuracy.SOLUTION: A ranging device includes a communication processing unit that performs a first wireless communication using right-handed circular polarization and a second wireless communication using left-handed circular polarization as communication for ranging using a phase-based method with another device, and a ranging unit that measures the distance to the other device on the basis of a first time waveform obtained by performing an inverse Fourier transform on the frequency characteristics of a signal transmission path obtained on the basis of a received signal via the first wireless communication and a second time waveform obtained by performing an inverse Fourier transform on the frequency characteristics of the signal transmission path obtained on the basis of a received signal via the second wireless communication.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present technology relates to a distance measuring device and a mobile terminal device, and more particularly to a technology regarding a distance measuring device and a mobile terminal device that measures distance by transmitting and receiving circularly polarized radio waves. [Background technology]

[0002] Distance measurement accuracy is important for properly measuring the distance between devices. The following Patent Document 1 discloses a technique for improving distance measurement accuracy by switching directivity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 171997 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when radio waves are transmitted from one device to another device, if the time at which the direct wave is received by the other device is close to the time at which the reflected wave is received, there is a risk that simply switching the directivity will not be enough to extract the direct wave.

[0005] The present technology is intended to solve the above problems and aims to improve distance measurement accuracy. [Means for solving the problem]

[0006] The ranging device of the present technology includes a communication processing unit that performs a first wireless communication using right-handed circular polarization and a second wireless communication using left-handed circular polarization as communications for ranging using a phase-based method between another device, and a ranging unit that measures the distance to the other device based on a first time waveform obtained by performing an inverse Fourier transform on the frequency characteristics of a signal transmission path obtained based on a received signal via the first wireless communication and a second time waveform obtained by performing an inverse Fourier transform on the frequency characteristics of a signal transmission path obtained based on a received signal via the second wireless communication. For example, the direct wave component from another device can be identified by using a first time waveform when an antenna receives a circularly polarized radio wave that is easier for the antenna to receive out of right-handed and left-handed circularly polarized waves, and a second time waveform when an antenna receives a circularly polarized radio wave that is harder for the antenna to receive (or vice versa).

[0007] The ranging method of the present technology is one in which a calculation processing device executes a communication process of performing a first wireless communication using right-handed circular polarization and a second wireless communication using left-handed circular polarization with another device as communications for ranging using a phase-based method, and a process of measuring the distance to the other device based on a first time waveform obtained by performing an inverse Fourier transform on the frequency characteristics of a signal transmission path obtained based on a received signal via the first wireless communication and a second time waveform obtained by performing an inverse Fourier transform on the frequency characteristics of a signal transmission path obtained based on a received signal via the second wireless communication. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of a manner in which radio waves are transmitted and received in an embodiment of the present technology, illustrating a state in which a distance measuring device receives a direct wave and a wave reflected by a reflecting object. [Diagram 2] FIG. 1 is a block diagram of a computer device. [Diagram 3] 2 is a block diagram of each unit included in the distance measuring device for transmitting and receiving radio waves. FIG. [Figure 4] FIG. 2 is a functional block diagram of a calculation processing unit. [Diagram 5]FIG. 1 is a diagram showing an example of phase measurement in a phase-based method, in which radio waves are transmitted from a distance measuring device to a base station. [Figure 6] FIG. 1 is a diagram showing an example of phase measurement in a phase-based method, in which the distance measuring device receives radio waves from a base station. [Figure 7] FIG. 2 is an explanatory diagram of the phase of a signal propagation path measured in a phase-based method. [Figure 8] 11 is a diagram illustrating an example of phase characteristics with respect to frequency when a communication device is displaced. [Figure 9] FIG. 11 is a diagram illustrating an example of a slope calculated from a phase characteristic. [Figure 10] FIG. 1 is an explanatory diagram for explaining an example of a positioning method, and this diagram shows a state in which the positioning method is used in an ideal state. [Figure 11] FIG. 1 is an explanatory diagram for explaining an example of a positioning method, and this diagram shows a state in which the positioning method is used in a state including an error. [Figure 12] 1 is a block diagram showing an example of a configuration of a distance measuring device for reducing the influence of multipath. [Figure 13] FIG. 2 is a diagram for explaining a cross dipole antenna. [Figure 14] 11 is a diagram showing an example of a first time waveform acquired when a first method is used as a method for identifying a direct wave component. FIG. [Figure 15] 13 is a diagram showing an example of a second time waveform acquired when a first method is used as a method for identifying a direct wave component. FIG. [Figure 16] FIG. 11 is a diagram showing changes in a reception flag when a first method is used as a method for identifying a direct wave component. [Figure 17] 13 is a diagram showing an example of a first time waveform acquired when a second method is used as a method for identifying a direct wave component. FIG. [Figure 18] 13 is a diagram showing an example of a second time waveform acquired when a second method is used as a method for identifying a direct wave component. FIG. [Figure 19]13 is a diagram showing an example of a differential waveform acquired when a second method is used as a method for identifying a direct wave component. FIG. [Figure 20] 4 is a flowchart showing a flow of processing executed by the distance measuring device to perform distance measurement. [Figure 21] This is an example of a configuration provided in a distance measuring device for reducing the influence of multipath, and this figure is a block diagram showing an example of a configuration provided in a distance measuring device that does not switch polarization. [Figure 22] This is an example of a configuration provided in a distance measuring device to reduce the influence of multipath, and this figure is a block diagram showing an example of the configuration of a distance measuring device having a hybrid coupler. [Diagram 23] This is an example of a configuration that a distance measuring device has to reduce the effects of multipath, and this figure is a block diagram showing an example of the configuration of a distance measuring device that has both an antenna for right-handed circular polarization and an antenna for left-handed circular polarization. [Figure 24] FIG. 2 is a diagram for explaining a patch antenna. [Diagram 25] FIG. 13 is a diagram showing an example in which two pairs of monopole antennas are used. [Figure 26] A diagram showing an example using two pairs of inverted F antennas. [Figure 27] FIG. 13 is a diagram showing an example in which a planar inverted F antenna is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The embodiments will be described below in the following order. <1. Communication using circularly polarized waves> <2. Configuration of distance measuring device> <3. Phase-based distance and positioning> <4. How to identify direct wave components> <4-1. First method> <4-2. Second method> <4-3.Distance measurement method> <5. Processing flow> <6. Variations> <6-1. First modified example> <6-2. Second modified example> <6-3.Third modified example> <6-4. Fourth modified example> <6-5.Other> <7. Summary> <8. This Technology>

[0010] <1. Communication using circularly polarized waves> In order to improve the degradation of distance measurement accuracy due to multipath, in this embodiment, communication is performed using circularly polarized radio waves. First, transmission and reception using circularly polarized waves in an ideal environment will be described with reference to FIG. FIG. 1 is a diagram showing an environment for accurately measuring the position information of a distance measuring device 1 serving as a mobile terminal such as a smartphone carried by a user.

[0011] The distance measuring device 1 measures the distance to the base station 2 by transmitting and receiving radio waves to the base station 2 whose location information is known. It is also possible to specify (estimate) its own location information by measuring the distance to multiple base stations 2.

[0012] The base station 2 emits right-hand circularly polarized (RHCP) radio waves, and the distance measuring device 1 receives the right-hand circularly polarized radio waves.

[0013] Here, since there is a reflecting object OB which is a perfect conductor around the distance measuring device 1 and the base station 2, the distance measuring device 1 not only receives the direct wave DW in the radio waves transmitted from the base station 2, but also receives the reflected wave RW reflected by the reflecting object OB.

[0014] When the RHCP radio wave emitted from the base station 2 is specularly reflected by a reflecting object OB, it is converted into a left-hand circularly polarized wave (LHCP) and received by the distance measuring device 1 .

[0015] Therefore, by adopting a configuration in which the distance measuring device 1 can receive only the radio waves of the RHCP, it is not necessary to receive the reflected wave once. This allows the direct wave component to be detected with high accuracy, so that the distance between the distance measuring device 1 and the base station 2 can be calculated with high accuracy, and highly accurate position information of the distance measuring device 1 can be obtained.

[0016] However, in an actual environment, perfect specular reflection does not always occur at the reflecting object OB, and the reflected wave at the reflecting object OB is not a perfect LHCP radio wave. Therefore, the distance measuring device 1 receives not only the direct wave but also the component of the one-time reflected wave, which reduces the distance measuring accuracy.

[0017] To solve this problem, the distance measuring device 1 has a configuration that will be described later.

[0018] <2. Configuration of distance measuring device> The distance measuring device 1 is a computer device that performs various calculations. An example of the hardware configuration of the computer device will be described with reference to FIG.

[0019] A CPU (Central Processing Unit) 71 of the computer device functions as an arithmetic processing unit that performs various processes, and executes the various processes according to a program stored in a ROM (Read Only Memory) 72 or a non-volatile memory unit 74 such as an EEP-ROM (Electrically Erasable Programmable Read-Only Memory), or a program loaded from a storage unit 79 to a RAM (Random Access Memory) 73. The RAM 73 also stores data necessary for the CPU 71 to execute the various processes, as appropriate.

[0020] The CPU 71 may be implemented as a DSP (Digital Signal Processor) or the like. The CPU 71 performs signal processing, which will be described later, to identify direct wave components and to perform distance measurement-related processing.

[0021] The CPU 71, ROM 72, RAM 73, and non-volatile memory unit 74 are interconnected via a bus 83. To this bus 83, an input / output interface (I / F) 75 is also connected.

[0022] The input / output interface 75 is connected to an input unit 76 including an operator and an operating device. For example, the input unit 76 may be various types of operators or operation devices such as a keyboard, a mouse, keys, a dial, a touch panel, a touch pad, or a remote controller. An operation by the user is detected by the input unit 76, and a signal corresponding to the input operation is interpreted by the CPU 71.

[0023] Further, a display unit 77 formed of an LCD or an organic EL (Electronic Luminescent) panel, etc., and an audio output unit 78 formed of a speaker, etc. are connected to the input / output interface 75 either integrally or separately. The display unit 77 is a display unit that performs various displays, and is configured, for example, by a display device provided in the housing of the computer device, or a separate display device connected to the computer device. The display unit 77 executes display of images for various image analysis processes, moving images to be processed, etc. on the display screen based on instructions from the CPU 71. Furthermore, the display unit 77 performs display of various operation menus, icons, messages, etc., that is, as a GUI (Graphical User Interface), based on instructions from the CPU 71.

[0024] The input / output interface 75 may be connected to a storage unit 79 configured with a hard disk or solid-state memory, or a communication unit 80 configured with a modem or the like.

[0025] The communication unit 80 performs communication processing via a transmission path such as the Internet, and communication with various devices via wired / wireless communication, bus communication, and the like. In the distance measuring device 1 of this embodiment, a communication section 80 including an antenna section and various switches, which will be described later, is provided, thereby enabling transmission and reception of at least one of the radio waves of the RHCP and the LHCP.

[0026] A drive 81 is also connected to the input / output interface 75 as required, and a removable storage medium 82 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory is appropriately mounted thereon. The drive 81 allows data files such as programs used in each process to be read from the removable storage medium 82. The read data files are stored in the storage unit 79, and images and sounds contained in the data files are output on the display unit 77 and the sound output unit 78. In addition, the computer programs and the like read from the removable storage medium 82 are installed in the storage unit 79 as necessary.

[0027] In this computer device, for example, software for the processing of this embodiment can be installed via network communication by the communication unit 80 or via a removable storage medium 82. Alternatively, the software may be stored in advance in the ROM 72, the storage unit 79, etc.

[0028] The CPU 71 performs processing operations based on various programs, thereby executing information processing and communication processing required in various information processing devices equipped with a calculation processing unit, which will be described later. The information processing device is not limited to being configured with a single computer device as shown in Fig. 2, but may be configured with a system of multiple computer devices. The multiple computer devices may be systemized using a LAN (Local Area Network) or the like, or may be located in a remote location using a VPN (Virtual Private Network) using the Internet or the like. The multiple computer devices may include computer devices serving as a server group (cloud) available through a cloud computing service.

[0029] FIG. 3 shows a specific example of a configuration of the distance measuring device 1 or the base station 2 for measuring distances by transmitting and receiving circularly polarized radio waves.

[0030] The distance measuring device 1 is equipped with a calculation processing unit 3, a modulator 4, a DAC (Digital to Analog Converter) 5, a transmission unit 6, a frequency synthesizer 7, a transmission amplifier 8, a transmission / reception switching unit 9, a distributor / synthesizer 10, a polarization switching unit 11, and an antenna unit 12 in order to transmit circularly polarized radio waves.

[0031] The distance measuring device 1 in this example is capable of performing wireless communication according to, for example, the BLE (Bluetooth Low Energy: Bluetooth is a registered trademark) system. The BLE system makes it possible to minimize the time required for operations that require large amounts of power, such as connection establishment and data communication. This makes it possible to reduce power consumption and make the distance measuring device 1 more compact.

[0032] The arithmetic processing unit 3 supplies data to be transmitted to a modulator 4 .

[0033] The modulator 4 performs modulation processing of signals for wireless communication with other devices such as the base station 2. In this example, IQ modulation is used as the modulation processing. In IQ modulation, an I channel (In-phase: in-phase component) and a Q channel (Quadrature: quadrature component) signal are used as baseband signals. Specifically, the modulator 4 performs modulation processing as IQ modulation on the data to be transmitted that is supplied from the arithmetic processing unit 3 .

[0034] The DAC 5 converts the digital signal from the modulator 4 into an analog signal. The analog signal converted by the DAC 5 is supplied to the transmission unit 6.

[0035] The transmitter 6 is a block that transmits signals by communication using radio waves. As shown in the figure, the transmitter 6 has a BPF (Band Pass Filter) 13 and a mixer 14. The BPF 13 passes only signals in a specific frequency band. In other words, the BPF 13 supplies only signals in a specific frequency band from the analog signal from the DAC 5 to the mixer 14.

[0036] The mixer 14 mixes the signal supplied from the BPF 13 with a local oscillation frequency supplied from the frequency synthesizer 7, thereby converting the signal into a transmission frequency for wireless communication.

[0037] The frequency synthesizer 7 supplies the frequency used during transmission and reception. Specifically, the frequency synthesizer 7 includes an internal local oscillator, and is used for conversion between high-frequency signals and baseband signals for wireless communication.

[0038] The transmission amplifier 8 amplifies the signal output from the transmission unit 6 .

[0039] The transmission / reception switching unit 9 is a switch that switches between high frequency (RF: Radio Frequency) signals. When transmitting data, the transmission / reception switching unit 9 connects the transmitting unit 6 to the distributor / synthesizer 10, thereby enabling radio waves to be transmitted from the antenna unit 12, and when receiving data, the transmission / reception switching unit 9 connects the receiving unit 16, which will be described later, to the distributor / synthesizer 10, thereby enabling radio waves to be received by the antenna unit 12.

[0040] When data is transmitted, the distributor / combiner 10 distributes the signal output from the transmission / reception switch 9 into two systems and outputs the distributed signals.

[0041] The polarization switching unit 11 applies a predetermined delay to one of the two signals output from the distributor / combiner 10. For example, the delay is applied so that the phase difference between the two signals becomes 90 deg. Two electric wires (feed lines) are connected to the antenna unit 12, and switching between RHCP and LHCP for radio waves is performed depending on which of the two electric wires the delayed signal is supplied to. The configurations of the distributor / synthesizer 10 and the polarization switching unit 11 will be described in detail later.

[0042] The antenna unit 12 is configured to have one or more antennas for transmitting and receiving signals by wireless communication. The antenna unit 12 in this embodiment is configured to have one antenna.

[0043] In order to receive circularly polarized radio waves, the distance measuring device 1 is equipped with a receiving amplifier 15, a receiving unit 16, and an ADC (Analog to Digital Converter) 17 in addition to a calculation processing unit 3, a transmission / reception switching unit 9, a distributor / synthesizer 10, a polarization switching unit 11, and an antenna unit 12.

[0044] The receiving unit 16 is a block that receives a signal by radio wave communication, and includes a mixer 18, a BPF 19, a VGA (Variable Gain Amplifier) ​​20, a BPF 21, and a VGA 22, as shown in FIG.

[0045] The antenna unit 12 receives RHCP or LHCP radio waves and outputs them to the polarization switching unit 11 via two electric wires.

[0046] The polarization switching unit 11 applies a delay to one of the two systems of received signals output from the antenna unit 12 and outputs the signal to the downstream distributor / combiner 10. At this time, depending on which of the two systems of received signals the delay is applied to, the received signal of the RHCP radio wave or the received signal of the LHCP radio wave is strengthened.

[0047] The distributor / synthesizer 10 combines the two systems of signals output from the polarization switching unit 11 into one system of signal, and outputs this to the receiving amplifier 15 via the transmission / reception switching unit 9 .

[0048] Receiving amplifier 15 amplifies the signal output from transmission / reception switch 9. Mixer 18 converts the signal supplied from receiving amplifier 15 into an I-channel signal and a Q-channel signal by mixing the signal with a local oscillation frequency supplied from frequency synthesizer 7. The I-channel signal (indicated as "Ich" in the figure) is supplied to BPF 19, and the Q-channel signal (indicated as "Qch" in the figure) is supplied to BPF 21.

[0049] The I-channel signal obtained by the mixer 18 is input to the BPF 19, where only signals in a specific frequency band are extracted, and then supplied to the VGA 20. On the other hand, the Q-channel signal obtained by the mixer 18 is input to the BPF 21, where only signals in a specific frequency band are extracted, and then supplied to the VGA 22.

[0050] The VGA 20 and VGA 22 function as analog variable gain amplifiers that adjust the gain of the I-channel signal supplied from the BPF 19 and the Q-channel signal supplied from the BPF 21, respectively.

[0051] The ADC 17 converts the I-channel and Q-channel signals from the receiving unit 16, that is, the I-channel and Q-channel signals output via the VGA 20 and VGA 22, from analog signals to digital signals. The I-channel and Q-channel signals converted into digital signals are supplied to an arithmetic processing unit 3 .

[0052] The arithmetic processing unit 3 performs processes such as demodulating the received data based on the data of the I-channel and Q-channel signals supplied from the ADC 17. In addition, as described above, the arithmetic processing unit 3 performs processes such as supplying data to be transmitted to the modulator 4 and modulating the data.

[0053] The arithmetic processing unit 3 performs processes such as demodulating the received data based on the data of the I-channel and Q-channel signals supplied from the ADC 17. In addition, as described above, the arithmetic processing unit 3 performs processes such as supplying data to be transmitted to the modulator 4 and modulating the data.

[0054] In addition, as shown in Figure 4, the calculation processing unit 3 of the distance measuring device 1 in this example has a function as a communication processing unit F1, a function as a switching unit F2, a function as a frequency phase characteristic acquisition unit F3, and a function as a distance measuring unit F4, all of which are functions for performing distance measuring using wireless communication.

[0055] The communication processing unit F1 performs processes such as supplying data to be transmitted to the modulator 4, demodulating received data based on the data of the I-channel and Q-channel signals, and switching between transmission and reception modes for each unit.

[0056] The switching unit F2 performs a process of switching between a first mode M1 for performing communication using RHCP radio waves and a second mode M2 ​​for performing communication using LHCP radio waves.

[0057] The frequency phase characteristic acquisition unit F3 acquires the phase characteristic with respect to the frequency of the signal propagation path between the communication device and another communication device (for example, the base station 2). In this example, distance measurement using wireless communication is performed by a phase-based method, and therefore a process is performed to obtain the phase characteristics with respect to the frequency of the signal propagation path. The phase-based distance measurement method will be explained later.

[0058] The distance measuring unit F4 calculates the distance to another communication device based on the phase characteristic with respect to the frequency of the signal propagation path acquired by the frequency phase characteristic acquisition unit F3. The method of calculating the distance by the distance measuring unit F4 will be described later.

[0059] <3. Phase-based distance and positioning> 5 and 6 are diagrams showing examples of phase measurement in the phase-based method. Note that the phase-based method is a technique that can be implemented without using circularly polarized radio waves. In the following description, an example using RHCP radio waves will be given.

[0060] In the phase-based method, the phase is measured based on the results of communication using RHCP radio waves while changing the frequency between two devices (in FIG. 5, between the distance measuring device 1 and the base station 2). In this case, first, as shown in FIG. 5, a measurement signal is transmitted from the distance measuring device 1 (initiator) to the base station 2 (reflector). The initiator here refers to a device that performs distance calculation processing based on the measured phase, and the reflector refers to a device that forms a pair with the initiator and exchanges measurement signals with the initiator.

[0061] Note that Figures 5 and 6 mainly show the flow of measurement signals related to phase measurement, and do not show, for example, the modulator 4, DAC 5, frequency synthesizer 7, transmission amplifier 8, distributor / synthesizer 10, polarization switching unit 11, and ADC 17. 5, in the distance measuring device 1 as an initiator, a measurement signal is transmitted from the arithmetic processing unit 3 through the transmitting unit 6 to the antenna of the antenna unit 12. In addition, in the base station 2 as a reflector, the receiving unit 16 receives the measurement signal through the antenna of the antenna unit 12.

[0062] 6, a measurement signal is returned from the base station 2 to the distance measuring device 1. That is, in the base station 2, the measurement signal is transmitted from the antenna of the antenna unit 12 via the transmission unit 6 from the calculation processing unit 3, and in the distance measuring device 1, the measurement signal is received by the reception unit 16 via the antenna of the antenna unit 12, and the phase characteristic between them is measured in the calculation processing unit 3. By performing round-trip communication in this manner, it becomes possible to properly measure the phase characteristics between the two devices.

[0063] FIG. 7 is an explanatory diagram of the phase θ of a signal propagation path measured in the phase-based method. 5, when a measurement signal is transmitted from the ranging device 1 to the base station 2, the signal phase φ of the measurement signal is measured in the base station 2. Here, the signal phase φ measured when such a measurement signal is transmitted from the ranging device 1 (initiator) to the base station 2 (reflector) is denoted as "φIR". 6B, when a measurement signal is transmitted from the base station 2 to the ranging device 1, the signal phase φ of the measurement signal is measured in the ranging device 1. The signal phase φ measured when a measurement signal is transmitted from the base station 2 to the ranging device 1 is denoted as "φRI". Here, the signal phase φ is calculated by the following [Equation 1], where the I-channel and Q-channel signals obtained by receiving the measurement signal are "I" and "Q", respectively.

[0064] φ=arctan(Q / I) [Equation 1]

[0065] In the phase-based method, the phase θ of the signal propagation path is calculated based on the above-mentioned signal phases φIR and φRI. Specifically, the phase θ is calculated by averaging these signal phases φIR and φRI. The averaging calculation here can be a calculation to calculate the average value of these signal phases φIR and φRI, or a calculation to add the signal phases φIR and φRI.

[0066] In the phase-based method, the phase θ is measured for each frequency while sequentially changing the frequency of the measurement signal within a predetermined frequency band. In other words, the phase θ is measured for each of a plurality of frequencies. Note that the "predetermined frequency band" here may be a frequency band determined as a band to be used in communication standards, such as the 2.4 GHz band (2400 MHz to 2480 MHz band) for BLE.

[0067] When the phase θ is measured for each frequency within a specified frequency band as described above, the measurement results are obtained as shown in Figure 8. The black circles in the figure represent the measurement results of the phase θ at each frequency. The results shown in FIG. 8 can be expressed in other words as the phase characteristics with respect to the frequency of the signal propagation path.

[0068] In the phase-based method, distance measurement is performed based on the change in phase θ when the frequency changes. Specifically, in the characteristics of phase θ relative to the change in frequency, the magnitude of the gradient of phase θ correlates with the distance as shown in FIG. 9. In this case, the steeper the gradient of phase θ, the greater the distance. Therefore, the distance can be calculated based on the gradient of phase θ.

[0069] One specific method for calculating distance is to calculate the group delay τ from the gradient of the phase θ, and then multiply the group delay τ by the speed of light (=299,792,458 m / s). The group delay τ is used to eliminate the effect of the 2π uncertainty of the phase. The group delay τ is obtained by differentiating the phase θ with respect to the angular frequency ω.

[0070] Here, the method of calculating the distance based on the characteristic of the phase θ with respect to the frequency, that is, the phase characteristic with respect to the frequency of the signal propagation path, is not limited to the above-mentioned method, and various methods are possible.

[0071] For example, it is possible to obtain not only the phase θ characteristic with respect to frequency but also the amplitude characteristic with respect to frequency, in other words, to obtain not only the frequency characteristic of the phase θ but also the frequency characteristic of the amplitude, and convert these phase θ and amplitude frequency characteristics into a waveform obtained by an inverse Fourier transform such as IFFT (Inverse Fast Fourier Transform) (a waveform with the horizontal axis being the time axis and the vertical axis being the signal intensity; hereinafter referred to as a "time waveform"), and to calculate the distance based on the time waveform.

[0072] Since the phase θ varies depending on the frequency, distance measurement using the phase-based method is, in principle, possible by measuring the phase θ for at least two or more frequencies. 6, the phase-based method calculates the distance by obtaining the phase θ from the measurement results of the signal phase φ in both directions from the ranging device 1 to the base station 2 and from the base station 2 to the ranging device 1. In other words, it is a method of obtaining the distance based on the relative difference information of the signal phase φ. Therefore, the phase-based method has the advantage of being able to prevent the accuracy of ranging from being reduced by the absolute value of the circuit delay of each block related to signal transmission and reception and the variation value due to temperature characteristics.

[0073] Next, positioning will be described with reference to FIG. 10 and FIG. For example, if the ranging device 1 measures distances to at least three base stations 2 and the distances D to the three base stations 2 can be determined, the position of the ranging device 1 can be determined by triangulation. Specifically, since the location of each base station 2 is known, the position of the ranging device 1 can be determined as the intersections (x marks in the figure) of three circles, as shown in Fig. 10, with the position of each base station 2 as the center and the distances D (D1, D2, and D3 in the figure) to each base station 2 as the radius. However, in practice, it is rare for the three circles to intersect at one point. That is, even if the circles intersect, there are usually multiple intersection points V. FIG. 11 shows a state in which the three circles do not intersect at one point, but rather generate a total of six intersection points V1, P2, P3, P4, P5, and P6. In this case, the position of the device to be positioned (i.e., the distance measuring device 1) can be calculated based on the area formed by these intersection points V. Specifically, among the three points that can be selected from the six intersection points V, three points that form a triangle with the smallest area by connecting the points are identified, in other words, three intersection points V that form the overlapping portion of the three circles (in the example shown in the figure, the three intersection points V2, P4, and P5), and the center of gravity of the triangle formed by the three points is determined as the position of the device to be positioned.

[0074] In addition, the positioning calculation method for identifying the position of the device to be positioned using the distance D between multiple base stations 2 is not limited to the positioning calculation method using the center of gravity method (centroid method) as described above, and various methods are possible, and the method is not limited to a specific method.

[0075] In this embodiment, a configuration is provided for reducing the influence of multipath, which is a problem when performing distance measurement or positioning as described above. Specifically, by providing the distance measuring device 1 with the distributor / synthesizer 10 and the polarization switching unit 11, the direct wave component can be identified, thereby reducing the effect of multipath.

[0076] A specific description will be given with reference to Fig. 12. Note that Fig. 12 shows only the arithmetic processing unit 3, the transmission / reception switching unit 9, the distributor / synthesizer 10, the polarization switching unit 11, and the antenna unit 12. In other words, the configuration of each unit provided between the arithmetic processing unit 3 and the transmission / reception switching unit 9 is omitted in Fig. 12.

[0077] The transmission / reception switching unit 9 is configured as, for example, an SPDT (Single-Pole / Double-Throw) switch, and switches between a transmission mode and a reception mode based on a transmission / reception switching signal S 1 supplied from the calculation processing unit 3 .

[0078] First, the operation of each part when the mode is switched to the transmission mode will be described. When the transmission / reception switching unit 9 is switched to the transmission mode by the transmission / reception switching signal S1, it outputs the signal from the transmission amplifier 8 to the distributor / combiner 10 at the subsequent stage.

[0079] As described above, when transmitting data, the distributor / combiner 10 distributes the signal output from the transmission / reception switch 9 into two systems and outputs the signals.

[0080] The polarization switching unit 11 includes a delay circuit 23 and a polarization switching switch 24 . The delay circuit 23 is provided to delay the phase of one of the two signals input from the distributor / synthesizer 10 by 90 degrees.

[0081] The polarization changeover switch 24 is configured as, for example, a DPDP (Double-Pole / Double-Throw) switch, and has four ports (a first port P1, a second port P2, a third port P3, and a fourth port P4).

[0082] 12, the output signal from the distributor-combiner 10 is input to the first port P1 via a delay circuit 23, and the output signal from the distributor-combiner 10 is input to the second port P2. In addition, the signal output from the third port P3 is input to the cross dipole antenna 25 of the antenna unit 12.

[0083] Here, the structure of the cross dipole antenna 25 will be briefly described (FIG. 13). The cross dipole antenna 25 has a structure in which two pairs of dipole antennas 25a and 25b are arranged at right angles to each other at 90 degrees.

[0084] Here, by setting the phase difference between the power feed signal supplied to the dipole antenna 25a and the power feed signal supplied to the dipole antenna 25b to 90 deg, it is possible to make the radio waves radiated from the cross dipole antenna 25 circularly polarized. In addition, when the power feed signal supplied to the dipole antenna 25a is set to +90° or -90° with respect to the power feed signal supplied to the dipole antenna 25b, the circular polarization of the radiated radio waves can be switched between RHCP and LHCP. In other words, by switching the method of feeding power to the cross dipole antenna 25, it is possible to switch between the radiation of radio waves in the first mode M1 and the radiation of radio waves in the second mode M2.

[0085] In other words, returning to Figure 12, when a signal with a phase delay of 90 deg by the delay circuit 23 is supplied to the antenna unit 12 from the third port P3, or when it is supplied to the antenna unit 12 from the fourth port P4, the radio waves radiated from the antenna unit 12 switch between RHCP and LHCP.

[0086] The polarization changeover switch 24 is thus configured as a switch for switching between RHCP and LHCP, and switches between a mode in which a signal input to the first port P1 is connected to the third port P3 and a signal input to the second port P2 is connected to the fourth port P4, and a mode in which a signal input to the first port P1 is connected to the fourth port P4 and a signal input to the second port P2 is connected to the third port P3.

[0087] Specifically, based on the polarization switching signal S2 supplied by the calculation processing unit 3, the polarization switching switch 24 switches the connection mode between the first port P1 and the second port P2 and the third port P3 and the fourth port P4, thereby switching between a first mode M1 in which communication is performed using RHCP radio waves and a second mode M2 ​​in which communication is performed using LHCP radio waves.

[0088] Next, the operation of each section when the transmission / reception switching section 9 is switched to the reception mode will be described.

[0089] In the cross dipole antenna 25 of the antenna section 12, signals which are shifted in phase by 90 degrees from each of the dipole antennas 25a, 25b are input to the polarization changeover switch .

[0090] Here, it is assumed that the polarization switching signal S2 is supplied from the arithmetic processing unit 3 to the polarization switching switch 24 for switching to the first mode M1 for receiving radio waves from the RHCP. At this time, for example, when a radio wave of an ideal RHCP is being received, the signal output from the first port P1 via the delay circuit 23 and the signal output from the second port P2 are in phase. When receiving data, the distributor / synthesizer 10 combines the two systems of signals output from the polarization switching unit 11 into one system of signal, and outputs this to the transmission / reception switching unit 9 . Therefore, both signals are combined in the distributor / combiner 10 and output as a received signal to the transmission / reception switch 9 at the subsequent stage.

[0091] On the other hand, when an ideal LHCP radio wave is being received, the signal output from the first port P1 via the delay circuit 23 and the signal output from the second port P2 are of opposite phase. Therefore, when both signals are combined in distributor / combiner 10, the signals cancel each other out, and no signal is output to transmission / reception switch 9.

[0092] Also, it is assumed that the polarization switching signal S2 is supplied from the arithmetic processing unit 3 to the polarization switching switch 24 for switching to the second mode M2 ​​for receiving LHCP radio waves. At this time, for example, when an ideal LHCP radio wave is being received, the signal output from the first port P1 via the delay circuit 23 and the signal output from the second port P2 are in phase. Therefore, both signals are combined in the distributor / combiner 10 and output as a received signal to the transmission / reception switch 9 at the subsequent stage.

[0093] On the other hand, when a radio wave of an ideal RHCP is being received, the signal output from the first port P1 via the delay circuit 23 and the signal output from the second port P2 are of opposite phase. Therefore, when both signals are combined in distributor / combiner 10, the signals cancel each other out, and no signal is output to transmission / reception switch 9.

[0094] In this manner, by switching the mode of the polarization switching unit 11 in response to the polarization switching signal S2 from the arithmetic processing unit 3, it is possible to switch between the RHCP radio waves and the LHCP radio waves to be received.

[0095] When the transmission / reception switching unit 9 is switched to the receiving mode by the transmission / reception switching signal S 1 , it outputs the signal from the distributor / combiner 10 to the receiving amplifier 15 .

[0096] In the explanation given here, it has been described that when an ideal LHCP radio wave is received in the first mode M1, or when an ideal RHCP radio wave is received in the second mode M2, no signal is output from the distributor-combiner 10. However, in a real environment, the radio waves received by the antenna unit 12 are a mixture of various types of radio waves and noise. Therefore, even if the RHCP radio waves radiated from the base station 2 are received in the incompatible second mode M2, some kind of signal is output from the distributor-combiner 10. Similarly, even if the LHCP radio waves radiated from the base station 2 are received in the incompatible first mode M1, some kind of signal is output from the distributor-combiner 10.

[0097] In the following explanation, the case where RHCP radio waves emitted from base station 2 are received in the first mode M1, or the case where LHCP radio waves are received in the second mode M2, i.e., the case where reception is performed in a corresponding mode, will be referred to as “reception in a corresponding mode.” In addition, when RHCP radio waves emitted from base station 2 are received in the second mode M2, or when LHCP radio waves are received in the first mode M1, i.e., when reception is in an incompatible mode, this is referred to as "reception in an incompatible mode."

[0098] <4. How to identify direct wave components> As described above, in order to perform distance measurement and positioning with high accuracy, it is important to identify the direct wave component of the radio waves radiated from base station 2 when receiving radio waves containing a mixture of various radio waves and noise.

[0099] In this embodiment, in order to identify the direct wave component, a time waveform obtained by receiving in the compatible mode and a time waveform obtained by receiving in the non-compatible mode are used.

[0100] Here, the time signal obtained by receiving radio waves in the first mode M1 for receiving radio waves from the RHCP is referred to as a first time waveform, and the time signal obtained by receiving radio waves in the second mode M2 ​​is referred to as a second time waveform.

[0101] In other words, if the radio waves emitted by base station 2 are RHCP, the first time waveform is a time waveform based on reception in a compatible mode, and the second time waveform is a time waveform based on reception in a non-compatible mode.

[0102] On the other hand, if the radio waves emitted by base station 2 are LHCP, the first time waveform is a time waveform based on reception in a non-compatible mode, and the second time waveform is a time waveform based on reception in a compatible mode.

[0103] Some methods will now be described with reference to the accompanying drawings.

[0104] <4-1. First method> The first method for identifying the direct wave component is a method using a noise judgment threshold Th1. Here, a case where the base station 2 emits a radio wave of the RHCP will be described.

[0105] FIG. 14 shows a first time waveform, which is a time waveform based on reception in the corresponding mode. FIG. 15 shows a second time waveform, which is a time waveform based on reception in a non-compatible mode.

[0106] In both figures, the horizontal axis represents time, and the vertical axis represents the signal strength of the received signal. The noise judgment threshold Th1 is a threshold for determining whether the received signal is noise or not. Specifically, if the noise judgment threshold Th1 is not exceeded, it is determined that only noise is being received, and if the noise judgment threshold Th1 is exceeded, it is determined that a signal other than noise, i.e., a signal that should be received, is being received.

[0107] 14, the signal strength of the received signal exceeds the noise determination threshold Th1 at the timing of time T1. Therefore, it is determined that the signal received after time T1 contains a direct wave component. In the following description, the period during which the direct wave is received is referred to as the "direct wave reception period Tr." Furthermore, in the first time waveform shown in FIG. 14, since a peak is located at time T2, there is a risk that it will be determined that a direct wave is being received around time T2.

[0108] Incidentally, in this embodiment, the direct wave component is determined using also the second time waveform, which is a time waveform based on reception in the non-compatible mode. In the second time waveform shown in FIG. 15, the signal strength of the received signal exceeds the noise determination threshold Th1 at the timing of time T3.

[0109] Figure 16 shows the results of determining the reception flag of the direct wave component (the period when a direct wave is received is set to 1, and the rest is set to 0) based on the first time waveform in Figure 14, and the results of determining the reception flag of the direct wave component based on the second time waveform in Figure 15.

[0110] As shown in the figure, the reception flags for both the first and second time waveforms are set to "1" around time T2. Therefore, it can be determined that a peak was formed during this period due to the reception of a large amount of noise components.

[0111] On the other hand, in the period from time T1 to time T3, the reception flag in the second time waveform, which is a time waveform based on reception in the non-compatible mode, is set to “0”, whereas the reception flag in the first time waveform, which is a time waveform based on reception in the compatible mode, is set to “1”.

[0112] That is, as shown in FIG. 14, a direct wave component is contained in the received signal that is likely to be buried in noise, and it can be determined that the period from time T1 to time T3 is the direct wave reception period Tr, or a period that includes the direct wave reception period Tr. That is, by using both the first time waveform and the second time waveform, it is possible to avoid erroneous determination of the direct wave reception period Tr based on the peak of the received waveform.

[0113] <4-2. Second method> The first method for identifying the direct wave component is to use a differential waveform obtained by calculating the difference between the first and second time waveforms. Here, a case where the base station 2 emits RHCP radio waves is described. This method is suitable for an environment where the same level of noise is received in both the first mode M1 and the second mode M2.

[0114] FIG. 17 shows a first time waveform, which is a time waveform based on reception in the corresponding mode. FIG. 18 shows a second time waveform, which is a time waveform based on reception in the non-compatible mode.

[0115] In both figures, the horizontal axis represents time and the vertical axis represents the signal strength of the received signal.

[0116] In the first time waveform shown in FIG. 17, a dull waveform is observed, and it is difficult to accurately identify the direct wave reception period Tr.

[0117] Therefore, the second time waveform in the non-compatible mode is acquired, and the difference is calculated to obtain a differential waveform. An example of the differential waveform is shown in Figure 19.

[0118] As shown in the figure, the noise components are cancelled, and the direct wave components can be identified with high accuracy.

[0119] In order to detect the rising edge of the direct wave component, a detection threshold Th2 may be used for the determination (see FIG. 19).

[0120] <4-3.Distance measurement method> After identifying the direct wave component using the first or second method, a process of measuring the distance to the base station 2 is performed. The horizontal axis in each of Fig. 14 to Fig. 19 is the time axis, which can be said as the axis representing the distance to the base station 2. Specifically, the distance to the base station 2 can be calculated by multiplying the time when the direct wave component was detected by the speed of light.

[0121] It should be noted that positioning can be performed by measuring the distances to a plurality of base stations 2 using this technique.

[0122] <5. Processing flow> The flow of processing executed by the arithmetic processing unit 3 (CPU 71) of the distance measuring device 1 to measure distance will be described with reference to FIG.

[0123] In step S101, the calculation processing unit 3 sets the first mode M1 to receive radio waves from the RHCP.

[0124] Next, in step S102, the calculation processing unit 3 performs a transmission / reception process. In the transmission / reception process, the radio wave of the RHCP transmitted from the base station 2 is received by the distance measuring device 1, and the radio wave transmitted by the distance measuring device 1 is received by the base station 2. This process is performed to obtain the phase θ for each frequency within a predetermined frequency band, thereby obtaining the phase characteristics of the signal propagation path with respect to frequency.

[0125] In step S103, the calculation processing unit 3 obtains a first time waveform as shown in FIG. 14 or FIG. 17 from the phase characteristic.

[0126] In step S104, the calculation processing unit 3 sets the second mode M2 ​​to receive radio waves of the LHCP.

[0127] In step S105, the processor 3 performs a transmission / reception process. The transmission / reception process is performed between the base station 2 and the distance measuring device 1, similar to step S102.

[0128] In step S106, the calculation processing unit 3 obtains a second time waveform as shown in FIG. 15 or FIG. 18 from the phase characteristic.

[0129] In step S107, the calculation processing unit 3 detects a direct wave component using the first time waveform and the second time waveform. Specifically, as described above, the reception flag may be used, or a differential waveform may be calculated and used.

[0130] In step S108, the calculation processing unit 3 calculates the distance based on the detection result of the direct wave component.

[0131] <6. Variations> Various modified examples will be described. <6-1. First modified example> In the above example, the distance measuring device 1 receives either RHCP or LHCP radio waves transmitted from the base station 2 by switching between the first mode M1 and the second mode M2. For example, in the above example, the base station 2 is capable of transmitting only RHCP radio waves, and the distance measuring device 1 receives the RHCP radio waves in the first mode M1 as well as in the second mode M2.

[0132] In the first modification, the base station 2 is capable of transmitting both RHCP radio waves and LHCP radio waves, and the distance measuring device 1A is capable of receiving only either the RHCP radio waves or the LHCP radio waves. That is, the distance measuring device 1A is capable of adopting only one of the first mode M1 and the second mode M2.

[0133] An example of the configuration of a distance measuring device 1A is shown in Fig. 21. Note that in Fig. 21, similar to Fig. 12, the configuration of each unit provided between the calculation processing unit 3 and the transmission / reception switching unit 9 is omitted.

[0134] The distance measuring device 1A does not include the polarization switching unit 11, and therefore is capable of transmitting and receiving using only either the RHCP radio waves or the LHCP radio waves.

[0135] By switching the radio waves transmitted by the base station 2 between RHCP and LHCP, it is possible for the ranging device 1A to acquire a first time waveform based on reception in a compatible mode and a second time waveform based on reception in a non-compatible mode.

[0136] As described above, even if the distance measuring device 1 is configured to be switchable between the first mode M1 and the second mode M2, the same thing as this modified example can be achieved by fixing it to one of the modes.

[0137] <6-2. Second modified example> The distance measuring device 1 described above is provided with the distributor / synthesizer 10 and the polarization switching unit 11, thereby enabling transmission and reception of RHCP radio waves and LHCP radio waves. A distance measuring device 1B in the second modified example includes a polarization changeover switch 24B and a hybrid coupler 26 instead of the distributor-synthesizer 10 and the polarization changeover unit 11.

[0138] An example of the configuration of a distance measuring device 1B is shown in Fig. 22. Note that in Fig. 22, the configuration of each unit provided between the calculation processing unit 3 and the transmission / reception switching unit 9 is omitted, similar to Figs. 12 and 21.

[0139] The distance measuring device 1B includes a polarization changeover switch 24B and a hybrid coupler .

[0140] The polarization changeover switch 24B is configured as an SPDT switch or the like, and functions as the polarization changeover unit 11 in FIG. The hybrid coupler 26 has four ports: a first port Po1, a second port Po2, a third port Po3, and a fourth port Po4.

[0141] The two ports on the double-throw side of the polarization changeover switch 24B are connected to the first port Po1 and the second port Po2, respectively. The hybrid coupler 26 can adjust the phase difference between the signal output from the third port Po3 and the signal output from the fourth port Po4 to 90 deg.

[0142] The behavior of the distance measuring device 1B when transmitting RHCP or LHCP radio waves will be described. The hybrid coupler 26 can switch between when a signal is input to the first port Po1 and when a signal is input to the second port Po2, so that the signal output from the third port Po3 leads or lags the signal output from the fourth port Po4 by 90 degrees.

[0143] That is, the polarization switching switch 24B can switch between outputting a signal to the first port Po1 or to the second port Po2 based on the polarization switching signal S2 supplied from the calculation processing unit 3, thereby switching the phase difference between the two signals output from the hybrid coupler 26 between 90deg and -90deg.

[0144] This allows the radio waves output from the cross dipole antenna 25 to be switched between RHCP and LHCP.

[0145] Next, the behavior of the distance measuring device 1B when receiving radio waves transmitted from the base station 2 will be described.

[0146] One of the two signals output from the cross dipole antenna 25 is input to the third port Po3 of the hybrid coupler 26, and the other is input to the fourth port Po4. In addition, the phase difference between the two output signals switches between 90 deg and -90 deg depending on whether the cross dipole antenna 25 receives an RHCP radio wave or an LHCP radio wave.

[0147] When the signal input to the third port Po3 is delayed by 90 deg from the signal input to the fourth port Po4, the hybrid coupler 26 outputs a signal from the first port Po1. At this time, no signal is output from the second port Po2.

[0148] Furthermore, when the signal input to the third port Po3 leads the signal input to the fourth port Po4 by 90 deg, the hybrid coupler 26 outputs a signal from the second port Po2. At this time, no signal is output from the first port Po1.

[0149] Therefore, the arithmetic processing unit 3 can be configured to receive only one of the radio waves of either RHCP or LHCP by switching the polarization switch 24B to receive only the output signal from the first port Po1 by the polarization switching signal S2. Also, the arithmetic processing unit 3 can be configured to receive only the other circularly polarized radio wave by switching the polarization switch 24B to receive only the output signal from the second port Po2 by the polarization switching signal S2.

[0150] That is, the arithmetic processing unit 3 is capable of switching between the first mode M1 and the second mode M2 ​​by the polarization switching signal S2.

[0151] Even if such a configuration is adopted, the above-mentioned effects can be obtained.

[0152] <6-3.Third modified example> In the above-described example, the antenna section 12 is provided with only one antenna (cross dipole antenna 25), but the antenna section 12C in the distance measuring device 1C in the third modified example is provided with two cross dipole antennas 25R, 25L.

[0153] The configuration of a distance measuring device 1C is shown in Fig. 23. Note that in Fig. 23, the configuration of each unit provided between the calculation processing unit 3 and the transmission / reception switching unit 9 is omitted, similar to Figs. 12, 21 and 22.

[0154] The distance measuring device 1C includes a configuration for RHCP and a configuration for LHCP for each of the transmission / reception switching unit 9, the distributor / combiner 10, the delay circuit 23, and the cross dipole antenna 25.

[0155] Specifically, as components for transmitting and receiving radio waves of the RHCP, the distance measuring device 1C includes a transmission / reception switching unit 9R, a distributor / combiner 10R, a delay circuit 23R, and a cross dipole antenna 25R.

[0156] Further, as components for transmitting and receiving radio waves of the LHCP, the distance measuring device 1C includes a transmission / reception switching unit 9L, a distributor / synthesizer 10L, a delay circuit 23L, and a cross dipole antenna 25L.

[0157] The arithmetic processing unit 3 supplies a transmission / reception switching signal S1R to the transmission / reception switching unit 9R, thereby switching between a transmission mode and a reception mode in communication using the cross dipole antenna 25R. Moreover, the arithmetic processing unit 3 supplies a transmission / reception switching signal S1L to the transmission / reception switching unit 9L to switch between a transmission mode and a reception mode in communication using the cross dipole antenna 25L.

[0158] The configuration of the distance measuring device 1C is such that, for example, when base station 2 transmits RHCP radio waves, it can receive the signal in a compatible mode using each unit that is compatible with transmitting and receiving RHCP radio waves, and at the same time, it can receive the signal in a non-compatible mode using each unit that is compatible with transmitting and receiving LHCP radio waves.

[0159] Therefore, since the first and second time waveforms can be acquired almost simultaneously, for example, even in an environment where noise in a signal propagation path changes over time, the influence of noise variations on the first and second time waveforms can be minimized. That is, the configuration of the distance measuring device 1C can improve the distance measuring accuracy.

[0160] In the distance measuring device 1C shown in FIG. 23, the transmission / reception switching unit 9, distributor / combiner 10, and delay circuit 23 are configured to have one each for the RHCP and the LHCP, but it is also possible to configure some of them to be shared between the RHCP and the LHCP.

[0161] <6-4. Fourth modified example> The antenna section 12 (12C) in each of the above-mentioned examples includes the cross dipole antenna 25 (25R, 25L). The configuration of the antenna for transmitting and receiving radio waves of the RHCP and the LHCP is not limited to the cross dipole antenna, and may be, for example, a patch antenna 27 as shown in FIG.

[0162] Specifically, the antenna section 12 is configured to include a patch antenna 27 formed in a substantially rectangular shape, and a first electric wire 28 and a second electric wire 29 connected to each of electrodes provided on two adjacent sides of the patch antenna 27.

[0163] When transmitting wireless radio waves, RHCP or LHCP wireless radio waves can be emitted by supplying signals with a phase difference of 90 degrees to the first electric wire 28 and the second electric wire 29. Then, by switching the phase of the signal supplied to the first electric wire 28 relative to the signal supplied to the second electric wire 29 between +90 degrees and -90 degrees, it is possible to switch between communication using RHCP wireless radio waves and communication using LHCP wireless radio waves.

[0164] Furthermore, when receiving RHCP or LHCP radio waves, signals with a phase difference of 90 deg are output to the subsequent stage from the first electric wire 28 and the second electric wire 29. By appropriately switching the mode in the subsequent stage between the first mode M1 and the second mode M2, it is possible to receive RHCP or LHCP radio waves.

[0165] <6-5.Other> In each of the above examples, the delay circuit 23 (23R, 23L) is provided so that the phase difference is 90 deg., but it is not necessary to delay one of the signals so that the phase difference is exactly 90 deg.

[0166] For example, the phase difference may be between 30 degrees and 150 degrees, or the phase difference may be between 210 degrees and 330 degrees. In addition, when switching from a mode that emits RHCP radio waves to a mode that emits LHCP radio waves during transmission, this can be achieved by changing the phase difference between the two signals supplied to the antenna section 12 (12C) from a state in which the phase difference is between 30 degrees and 150 degrees to a state in which the phase difference is between 210 degrees and 330 degrees.

[0167] <7. Summary> As described in each of the above examples, the ranging device 1 (1A, 1B, 1C) is equipped with a communication processing unit F1 that performs a first wireless communication (transmission and reception based on RHCP) using right-handed circularly polarized waves and a second wireless communication (transmission and reception based on LHCP) using left-handed circularly polarized waves as communications for ranging using a phase-based method with another device (e.g., base station 2), and a ranging unit F4 that measures the distance to the other device based on a first time waveform (see Figures 14 and 17) obtained by inverse Fourier transforming the frequency characteristics of the signal transmission path obtained based on the received signal via the first wireless communication and a second time waveform (see Figures 15 and 18) obtained by inverse Fourier transforming the frequency characteristics of the signal transmission path obtained based on the received signal via the second wireless communication. For example, the direct wave component from another device can be identified by using a first time waveform when an antenna receives a circularly polarized radio wave that is easier for the antenna to receive out of right-handed and left-handed circularly polarized waves, and a second time waveform when an antenna receives a circularly polarized radio wave that is harder for the antenna to receive (or vice versa). This makes it possible to calculate the distance to other devices with high accuracy. In addition, the primary reflected wave component can be excluded, making it possible to further improve distance measurement accuracy.

[0168] As described in the first modified example with reference to FIG. 21 etc., the first wireless communication may be communication for receiving right-handed circularly polarized (RHCP) radio waves, and the second wireless communication may be communication for receiving left-handed circularly polarized (LHCP) radio waves. The first and second time waveforms can be obtained by receiving two types of radio waves, right-handed circularly polarized waves and left-handed circularly polarized waves, transmitted from another device (base station 2) using an antenna (cross dipole antenna 25R or cross dipole antenna 25L) that supports either one of the circularly polarized waves. By using these two time waveforms, it is possible to identify the direct wave from the other device, making it possible to perform highly accurate distance measurement.

[0169] As explained in the first modified example with reference to FIG. 21 etc., the distance measuring device 1A may be provided with a signal receiving unit (e.g., an antenna unit 12, a polarization switching unit 11, a distributor / synthesizer 10) that supports either right-handed circularly polarized (RHCP) radio waves or left-handed circularly polarized (LHCP) radio waves radiated from another device (base station 2). More specifically, the distance measuring device 1A includes an antenna unit 12 that outputs a received signal having a phase difference based on the reception of radio waves, and a combining unit (delay circuit 23 and distributor / combiner 10) that combines the received signals output from the antenna unit 12, and the combining unit may be capable of receiving either right-handed circularly polarized (RHCP) radio waves or left-handed circularly polarized (LHCP) radio waves. As a result, when the base station 2 sequentially radiates both right-handed circularly polarized radio waves and left-handed circularly polarized radio waves, the rotation direction of the circularly polarized wave as a direct wave component is opposite to the rotation direction of the circularly polarized wave corresponding to the antenna unit 12 for at least one of the receptions in the antenna unit 12. Therefore, one of the first time waveform and the second time waveform does not contain many direct wave components but contains many noise components, making it possible to identify the noise components.

[0170] As described with reference to Figures 12, 22, etc., the distance measuring device 1 (1B, 1C) includes an antenna unit 12 that outputs a received signal when receiving radio waves, a synthesis unit (distributor / synthesizer 10 and delay circuit 23) that synthesizes the received signals output from the antenna unit 12, and a switching unit F2 that switches between a first mode M1 in which the synthesis unit performs synthesis corresponding to reception of right-handed circularly polarized (RHCP) radio waves and a second mode M2 ​​in which the synthesis unit performs synthesis corresponding to reception of left-handed circularly polarized (LHCP) radio waves, and the first wireless communication may be radio wave communication performed in a state switched to the first mode M1, and the second wireless communication may be radio wave communication performed in a state switched to the second mode M2. That is, the switching unit F2 switches the polarization switching unit 11 or the polarization switching switch 24B to the first mode M1, so that the synthesis unit performs synthesis corresponding to reception of right-handed circularly polarized radio waves, and switches the polarization switching unit 11 or the polarization switching switch 24B to the second mode M2, so that the synthesis unit performs synthesis corresponding to reception of left-handed circularly polarized radio waves. This makes it possible to receive either right-handed circularly polarized radio waves or left-handed circularly polarized radio waves transmitted from another device (base station 2) in the first mode M1 or the second mode M2.

[0171] As described with reference to each of Figures 14 to 19 as a method for identifying a direct wave component, the first wireless communication may be communication for receiving radio waves of a specific circular polarization, which is either right-handed circular polarization (RHCP) or left-handed circular polarization (LHCP), with the combining unit (delay circuit 23 and distributor / combiner 10) switched to the first mode M1, and the second wireless communication may be communication for receiving radio waves of a specific circular polarization with the combining unit switched to the second mode M2. As a result, reception is performed in both a mode in which the rotation direction of the circularly polarized waves of the radio waves received from another device (base station 2) matches (compatible mode) and a mode in which the rotation direction does not match (non-compatible mode), and the first and second time waveforms are acquired. Therefore, it is possible to identify the direct wave from the other device, and it is possible to perform highly accurate distance measurement.

[0172] As explained with reference to Figures 12, 13, 24, etc., the antenna section 12 (12C) provided in the distance measuring device 1 (1A, 1B, 1C) may be either a cross dipole antenna 25 (25R, 25L) or a patch antenna 27. This makes it possible to perform highly accurate distance measurement using the cross dipole antenna 25 and the patch antenna 27. Further, the distance measuring device 1 may have a structure using two pairs of monopole antennas instead of the cross dipole antenna 25. Specifically, as shown in Fig. 25, the device is configured to have a ground plate 30 and two pairs of monopole antennas 31a and 31b, and a feed signal with a phase difference of 90 deg is applied to each of the monopole antennas 31a and 31b. Alternatively, the distance measuring device 1 may have a structure using two pairs of inverted-F antennas instead of the cross dipole antenna 25. Specifically, as shown in Fig. 26, the device is configured to have a ground plate 30 and two pairs of inverted-F antennas 32a and 32b, and a feed signal with a phase difference of 90 deg is applied to each of the inverted-F antennas 32a and 32b. Furthermore, the distance measuring device 1 may be configured to include a planar inverted-F antenna instead of the patch antenna 27. Specifically, as shown in Fig. 27, the device includes a ground plate 30 and a planar inverted-F antenna 32, and supplies a signal with a phase difference of 90 deg to a first electric wire 34a and a second electric wire 34b that supply signals to the planar inverted-F antenna 32. These modified examples are merely examples, and the distance measuring device 1 may achieve high-precision distance measurement by adopting various other antenna configurations.

[0173] As described with reference to FIG. 13 etc., the switching unit F2 may switch between emitting radio waves in the first mode M1 and emitting radio waves in the second mode M2 ​​by switching the method of feeding power to the antenna unit 12 (12C). For example, when the antenna unit 12 is composed of two pairs of dipole antennas 25a, 25b, the phase difference between the power feed signals applied to the first dipole antenna 25a and the second dipole antenna 25b is set to 90 degrees. In this case, by switching between a power feed method in which the power feed signal to the first dipole antenna 25a is advanced in phase by 90 degrees and a power feed method in which the power feed signal to the second dipole antenna 25b is advanced in phase by 90 degrees, it is possible to switch between the radiation of radio waves in the first mode M1 and the radiation of radio waves in the second mode M2. This makes it possible to switch between communications using right-hand circularly polarized (RHCP) radio waves and communications using left-hand circularly polarized (LHCP) radio waves. Furthermore, when the antenna unit 12 is a patch antenna 27, feed signals with a phase shift of 90 degrees are supplied to two electrodes provided on the patch antenna 27. Then, by interchanging the feed signals supplied to the two electrodes, it is possible to switch between radio wave radiation in the first mode M1 and radio wave radiation in the second mode M2. By switching the mode, it is possible to switch between communication using right-handed circularly polarized radio waves and communication using left-handed circularly polarized radio waves.

[0174] As described elsewhere, the switching unit F2 may switch modes by switching the phase difference between the two types of power supply signals supplied to the antenna unit 12 (12C) from a state in which the phase difference is between 30 degrees and 150 degrees to a state in which the phase difference is between 210 degrees and 330 degrees. This makes it possible to switch radio wave communications from right-hand circular polarization (RHCP) to left-hand circular polarization (LHCP), or vice versa.

[0175] As explained in the second variant with reference to Figure 23 etc., the distance measuring device 1B includes a switch element (polarization switching switch 24B) and a hybrid coupler 26 that distributes a signal input from the switch element and supplies it to the antenna unit 12 (12C) and combines the received signal output from the antenna unit 12 and outputs it to the switch element, and the switching unit F2 may switch modes by outputting a switching signal to the switch element. This makes it possible to receive circularly polarized radio waves corresponding to the mode selected by the switch element out of right-hand circularly polarized (RHCP) radio waves and left-hand circularly polarized (LHCP) radio waves received by the antenna unit 12. Since a predetermined phase difference, such as 90 deg, is automatically created in the hybrid coupler 26, the mode can be easily changed by simply switching the switch element.

[0176] As explained with reference to Figure 23 etc. in the third modified example, the antenna section 12C may have a first antenna (cross dipole antenna 25R) capable of transmitting and receiving radio waves in the first mode M1, and a second antenna (cross dipole antenna 25L) capable of transmitting and receiving radio waves in the second mode M2. By generating a first time waveform based on the received signal from the first antenna and generating a second time waveform based on the received signal from the second antenna, it is possible to identify an antenna suitable for receiving the direct wave component, enabling highly accurate ranging.

[0177] As explained with reference to each of Figures 14 to 16 in the first method of identifying the direct wave component, the distance measurement unit F4 may perform distance measurement by determining as a direct wave reception period Tr a time period in which the judgment results of whether or not the noise judgment threshold Th1 is exceeded are different between the first time waveform and the second time waveform. This prevents the reflected wave component from being mistakenly detected as a direct wave component, enabling appropriate distance measurement.

[0178] As explained with reference to each of Figures 17 to 19 in the second method for identifying the direct wave component, the distance measurement unit F4 may perform distance measurement based on the difference between the first time waveform and the second time waveform. This makes it possible to identify the direct wave component, and therefore the time period during which the direct wave component was mainly received, making it possible to perform appropriate distance measurement.

[0179] The above-mentioned functions as various distance measuring devices can be suitably implemented in mobile terminal devices such as smartphones, tablet terminals, etc. In the mobile terminal device, if the location information of the terminal itself can be determined with high accuracy, the usability of various applications can be improved. For example, when presenting advertisements using location information, appropriate advertising information can be sent based on highly accurate location information, while avoiding the sending of inappropriate advertising information, thereby improving user convenience and making effective use of communication bandwidth. Furthermore, in applications that perform navigation, in addition to reducing the presentation of erroneous guidance and preventing the user from making unnecessary journeys, it is possible to provide an easy-to-use navigation function. Furthermore, in game applications that use location information, a fair gaming environment can be provided by using highly accurate location information.

[0180] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0181] Furthermore, the above-mentioned examples may be combined in any manner, and even when various combinations are used, the above-mentioned various operational effects can be obtained.

[0182] <8. This Technology> (1) a communication processing unit that performs a first wireless communication using right-handed circularly polarized waves and a second wireless communication using left-handed circularly polarized waves as communications for distance measurement using a phase-based method with another device; a distance measuring unit that measures a distance to the other device based on a first time waveform obtained by performing an inverse Fourier transform on a frequency characteristic of a signal transmission path obtained based on a reception signal via the first wireless communication and a second time waveform obtained by performing an inverse Fourier transform on a frequency characteristic of a signal transmission path obtained based on a reception signal via the second wireless communication. Ranging device. (2) The first wireless communication is communication for receiving right-handed circularly polarized radio waves, The second wireless communication is communication for receiving left-handed circularly polarized radio waves. A distance measuring device as described in (1) above. (3) A signal receiving unit that can receive either a right-handed circularly polarized radio wave or a left-handed circularly polarized radio wave radiated from the other device is provided. A distance measuring device as described in (2) above. (4) The antenna unit outputs two types of reception signals having a phase difference based on the reception of circularly polarized radio waves, the signal receiving unit has a combining unit that combines the two types of received signals, The synthesis unit performs synthesis corresponding to either a right-handed circularly polarized radio wave or a left-handed circularly polarized radio wave. A distance measuring device as described in (3) above. (5) an antenna unit that outputs a reception signal based on reception of a radio wave; a combining unit that combines the received signals output from the antenna units; A switching unit that switches between a first mode in which the synthesis unit performs synthesis corresponding to reception of a right-handed circularly polarized radio wave signal and a second mode in which the synthesis unit performs synthesis corresponding to reception of a left-handed circularly polarized radio wave signal, the first wireless communication is a wireless radio wave communication performed in a state switched to the first mode, The second wireless communication is a radio wave communication performed in a state switched to the second mode. A distance measuring device as described in (1) above. (6) The first wireless communication is a communication for receiving a radio wave having a specific circular polarization, which is either a right-handed circular polarization or a left-handed circular polarization, with the synthesis unit switched to the first mode, The second wireless communication is communication for receiving the specific circularly polarized radio wave with the synthesis unit switched to the second mode. A distance measuring device as described in (5) above. (7) The antenna unit is either a cross dipole antenna or a patch antenna. A distance measuring device according to any one of (4) to (6) above. (8) The switching unit switches between the radiation of radio waves in the first mode and the radiation of radio waves in the second mode by switching a power supply method for the antenna unit. A distance measuring device according to any one of (5) to (6) above. (9) The switching unit switches the mode by switching the phase difference between the two types of power supply signals supplied to the antenna unit from a state in which the phase difference is between 30 degrees and 150 degrees to a state in which the phase difference is between 210 degrees and 330 degrees. A distance measuring device as described in (8) above. (10) A switch element; a hybrid coupler that distributes a signal input from the switch element, supplies the distributed signal to the antenna unit, and combines a received signal output from the antenna unit and outputs the combined signal to the switch element, The switching unit switches the mode by outputting a switching signal to the switch element. A distance measuring device as described in (9) above. (11) The antenna unit has a first antenna capable of transmitting and receiving radio waves in the first mode, and a second antenna capable of transmitting and receiving radio waves in the second mode. A distance measuring device according to any one of (5) to (6) above. (12) The distance measurement unit determines a time period in which a determination result of whether or not the first time waveform and the second time waveform have exceeded a threshold value differs as a direct wave reception period, and performs the distance measurement. A distance measuring device according to any one of (1) to (11) above. (13) The distance measurement unit performs the distance measurement based on a difference between the first time waveform and the second time waveform. A distance measuring device according to any one of (1) to (12) above. (14) A communication process for performing a first wireless communication using right-handed circularly polarized waves and a second wireless communication using left-handed circularly polarized waves with another device as communication for distance measurement using a phase-based method; a process of measuring a distance to the other device based on a first time waveform obtained by performing an inverse Fourier transform on a frequency characteristic of a signal transmission path obtained based on a received signal via the first wireless communication and a second time waveform obtained by performing an inverse Fourier transform on a frequency characteristic of a signal transmission path obtained based on a received signal via the second wireless communication, Distance measurement method. [Explanation of symbols]

[0183] 1, 1A, 1B, 1C range finder 2 Base station (other device) 12, 12C Antenna section 24 Polarization changeover switch (changeover section) 24B Polarization changeover switch (switch element) 25 Cross dipole antenna 25R Cross dipole antenna (first antenna) 25L Cross dipole antenna (second antenna) 26 Hybrid Coupler 27 Patch Antenna M1 1st mode M2 2nd mode Tr Direct wave reception period F1 Communication processing unit F2 switching section F4 distance measuring section

Claims

1. a communication processing unit that performs a first wireless communication using right-handed circularly polarized waves and a second wireless communication using left-handed circularly polarized waves as communications for distance measurement using a phase-based method with another device; a distance measuring unit that measures a distance to the other device based on a first time waveform obtained by performing an inverse Fourier transform on a frequency characteristic of a signal transmission path obtained based on a reception signal via the first wireless communication and a second time waveform obtained by performing an inverse Fourier transform on a frequency characteristic of a signal transmission path obtained based on a reception signal via the second wireless communication. Ranging device.

2. The first wireless communication is communication for receiving right-handed circularly polarized radio waves, The second wireless communication is communication for receiving left-handed circularly polarized radio waves.

2. A distance measuring device according to claim 1.

3. A signal receiving unit that can receive either a right-handed circularly polarized radio wave or a left-handed circularly polarized radio wave radiated from the other device is provided.

3. A distance measuring device according to claim 2.

4. an antenna unit that outputs two types of reception signals having a phase difference based on reception of a circularly polarized radio wave; the signal receiving unit has a combining unit that combines the two types of received signals, The synthesis unit performs synthesis corresponding to either a right-handed circularly polarized radio wave or a left-handed circularly polarized radio wave.

4. A distance measuring device according to claim 3.

5. an antenna unit that outputs a received signal when receiving a radio wave; a combining unit that combines the received signals output from the antenna units; A switching unit that switches between a first mode in which the synthesis unit performs synthesis corresponding to reception of a right-handed circularly polarized radio wave signal and a second mode in which the synthesis unit performs synthesis corresponding to reception of a left-handed circularly polarized radio wave signal, the first wireless communication is a wireless radio wave communication performed in a state switched to the first mode, The second wireless communication is a wireless radio wave communication performed in a state switched to the second mode.

2. A distance measuring device according to claim 1.

6. The first wireless communication is a communication for receiving a radio wave having a specific circular polarization, which is either a right-handed circular polarization or a left-handed circular polarization, with the synthesis unit switched to the first mode, The second wireless communication is communication for receiving the specific circularly polarized radio wave with the synthesis unit switched to the second mode.

6. A distance measuring device according to claim 5.

7. The antenna unit is either a cross dipole antenna or a patch antenna.

5. A distance measuring device according to claim 4.

8. The switching unit switches between the radiation of radio waves in the first mode and the radiation of radio waves in the second mode by switching a power supply method for the antenna unit.

6. A distance measuring device according to claim 5.

9. The switching unit switches the mode by switching the phase difference between the two types of power supply signals supplied to the antenna unit from a state in which the phase difference is between 30 degrees and 150 degrees to a state in which the phase difference is between 210 degrees and 330 degrees.

9. A distance measuring device according to claim 8.

10. A switch element; a hybrid coupler that distributes a signal input from the switch element, supplies the distributed signal to the antenna unit, and combines a received signal output from the antenna unit and outputs the combined signal to the switch element, The switching unit switches the mode by outputting a switching signal to the switch element.

10. A distance measuring device according to claim 9.

11. The antenna unit has a first antenna capable of transmitting and receiving radio waves in the first mode, and a second antenna capable of transmitting and receiving radio waves in the second mode.

6. A distance measuring device according to claim 5.

12. The distance measurement unit determines a time period in which a determination result of whether or not the first time waveform and the second time waveform have exceeded a threshold value differs as a direct wave reception period, and performs the distance measurement.

2. A distance measuring device according to claim 1.

13. The distance measurement unit performs the distance measurement based on a difference between the first time waveform and the second time waveform.

2. A distance measuring device according to claim 1.

14. A communication process for performing a first wireless communication using right-handed circularly polarized waves and a second wireless communication using left-handed circularly polarized waves with another device as communication for distance measurement using a phase-based method; a process of measuring a distance to the other device based on a first time waveform obtained by performing an inverse Fourier transform on a frequency characteristic of a signal transmission path obtained based on a received signal via the first wireless communication and a second time waveform obtained by performing an inverse Fourier transform on a frequency characteristic of a signal transmission path obtained based on a received signal via the second wireless communication, Distance measurement method.

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