JP2018200218A - Measuring device for measuring incoming radio wave and measuring method thereof - Google Patents

Abstract

An object of the present invention is to easily measure the direction of arrival of an incoming radio wave with a high angle resolution even when the reception intensity of the incoming radio wave fluctuates with time and to increase the accuracy of measurement of the direction of arrival. In each of a plurality of continuous movement measurement ranges in a movement path of a reception antenna, a reception signal of a reception antenna and a reference signal of a reference antenna fixedly arranged at a plurality of different movement positions or one movement position within the movement measurement range. Acquire multiple sets of. For each of a plurality of movement measurement ranges, time diversity is applied to a plurality of sets of reception signals and reference signals acquired within the movement measurement range to select reception signals and reference signals to be subjected to synthetic aperture processing, and time diversity is applied. Synthetic aperture processing is performed based on the received signal and reference signal of each of the selected plurality of moving measurement ranges and the rotation angle of the receiving antenna. The direction of the incoming radio wave is estimated based on the characteristics indicating the relationship between the received signal after the synthetic aperture processing and the rotation angle of the receiving antenna in each of the plurality of moving measurement ranges. [Selection] Figure 1

Description

  The present invention relates to a measuring apparatus for measuring an incoming radio wave and a measuring method thereof.

  Conventionally, arriving radio waves are received every predetermined time while rotating the receiving antenna, and the direction of the incoming radio waves is obtained by performing synthetic aperture processing on the received signal at each predetermined time based on the received signal of the reference antenna. A measuring device that measures the above is known (for example, see Non-Patent Document 1). According to this measuring apparatus, the direction of incoming radio waves can be easily measured with high angular resolution.

Tomimoto Kazuma, Yamaguchi Ryo: “Direction of arrival estimation using synthetic aperture processing”, IEICE Tech. 115, no. 286, AP2015-146, pp. 207-211, November 2015.

  In the above conventional measuring device, it is understood that when the received intensity of the incoming radio wave varies with time, the dynamic range when measuring the direction of the incoming radio wave by performing the synthetic aperture processing is deteriorated, and the measurement accuracy may be reduced. It was.

A measuring apparatus according to an aspect of the present invention is a measuring apparatus that measures an incoming radio wave, and includes a receiving antenna having directivity, an antenna driving unit that moves the receiving antenna, a fixedly arranged reference antenna, In each of a plurality of continuous movement measurement ranges in the movement path of the reception antenna, a plurality of different movement positions in the movement measurement range or received signals received via the reception antenna at one movement position in the movement measurement range A signal acquisition unit for acquiring a plurality of sets of reference signals received via the reference antenna, and time diversity for the plurality of sets of received signals and reference signals acquired within the movement measurement range for each of the plurality of movement measurement ranges To select a received signal and a reference signal to be processed by synthetic aperture processing, and to select the time diversity applied The synthetic aperture processing is performed based on the received signal and reference signal of each of the plurality of moving measurement ranges and the rotation angle of the receiving antenna, and the received signal after the synthetic aperture processing in each of the plurality of moving measurement ranges and the receiving antenna A signal processing unit that estimates a direction of the incoming radio wave based on a characteristic indicating a relationship with a rotation angle.
A measurement method according to another aspect of the present invention is a measurement method for measuring an incoming radio wave, and is a measurement method for measuring an incoming radio wave, wherein the receiving antenna having directivity is moved; and In each of a plurality of continuous movement measurement ranges in the movement path, a reception signal received via the reception antenna at a plurality of different movement positions within the movement measurement range and a reference signal received via a fixedly arranged reference antenna For each of the plurality of movement measurement ranges, and applying time diversity to the plurality of sets of reception signals and reference signals acquired within the movement measurement range, the received signal and reference for the synthetic aperture processing Selecting a signal, applying the time diversity, and selecting the received signal and the reference signal for each of the plurality of movement measurement ranges; and A synthetic aperture process based on a rotation angle of the transmission antenna, and the incoming radio wave based on a characteristic indicating a relationship between the reception signal after the synthetic aperture process and the rotation angle of the reception antenna in each of the plurality of movement measurement ranges Estimating the direction of.

In the measurement apparatus and the measurement method, the time diversity processing is performed for each of the plurality of movement measurement ranges, and the reference having the largest amplitude among the plurality of reference signals obtained through the reference antenna in the movement measurement range. Processing may be performed in which a signal is selected as a reference signal to be subjected to a synthetic aperture process, and a reception signal obtained through the reception antenna acquired at the same timing as the selected reference signal is selected as a reception signal to be subjected to a synthetic aperture process.
In the measurement apparatus and the measurement method, the time diversity processing is stopped every time the reception antenna is moved by a predetermined angle (for example, 1 °), and complex amplitude measurement is performed a plurality of times while the reception antenna is stopped. A plurality of sets of reception signals via the antenna and reference signals via the reference antenna are acquired, and a reference signal having the largest amplitude among the plurality of reference signals via the reference antenna is selected as a reference signal for the synthetic aperture processing And the process which selects the received signal via the said receiving antenna acquired at the same timing as the said selected reference signal as a received signal of synthetic aperture processing object may be sufficient.
In the measurement apparatus and the measurement method, for each of the plurality of movement measurement ranges, the reference antenna selected by applying the time diversity is used as a denominator, and the reception antenna acquired at the same timing as the selected reference signal The signal to be processed by the synthetic aperture may be derived using the received signal via the numerator.
Further, in the measurement apparatus and the measurement method, the synthetic aperture processing target signal obtained by multiplying the synthetic aperture processing target signal by a weight determined based on a standard deviation of the synthetic aperture processing window function, and multiplying the weight by the weight. The synthetic aperture processing may be performed based on the above.
In the measurement apparatus and the measurement method, the reception antenna may be rotationally driven so as to move in a state in which directivity is directed radially outward on a circular movement path away from the rotation center.
Further, in the measuring apparatus and the measuring method, the rotation angle of the receiving antenna in the i-th measurement point for performing synthetic aperture processing is set to receive the angle theta _i, a plurality of synthetic synthesized at the measurement point of the reception angle theta _i The angle difference between the reception angle θ _i of the rotation angle of the reception antenna corresponding to the j-th synthetic aperture processing target signal among the aperture processing target signals is φ _j , and the time diversity is selected to be selected The received signal and the reference signal at the rotation angle (θ _i + φ _j ) of the receiving antenna are E _Rx (θ _i + φ _j ) and E _Ref (θ _i + φ _j ), respectively, and the number of elements to be processed by the synthetic aperture is 2N + 1. (N: natural number), radius of the moving path of the receiving antenna is R, wave number of the incoming radio wave is k, and standard deviation of the window function of the synthetic aperture processing is σ Using the following formula (1) and (2) may calculate the received signal E _SA after the synthetic aperture processing in the reception angle θ _{i (θ i).}

  According to the present invention, it is possible to easily measure the arrival direction (DOA: Direction-of-Arrival) of an incoming radio wave with high angular resolution even when the reception intensity of the incoming radio wave arriving from an arbitrary direction varies with time. Measurement accuracy in the direction of arrival can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS (a) is explanatory drawing which shows an example of the incoming radio wave measuring apparatus using the synthetic aperture antenna which concerns on one Embodiment of this invention. (B) is explanatory drawing which shows an example of the movement path | route (rotation locus | trajectory) of the receiving antenna of the measuring apparatus. The flowchart which shows an example of the measurement of the incoming radio wave in the measuring apparatus of this embodiment. Explanatory drawing which shows an example of the synthetic aperture process in the measuring apparatus of this embodiment. The graph which shows an example of the simulation result which estimated the direction (DOA) of an incoming radio wave by the synthetic aperture process in the measuring apparatus of this embodiment. The graph which shows an example of the measurement result of the characteristic which shows the relationship between the amplitude of the received signal before performing the synthetic aperture process in case the time diversity is not applied in the measuring apparatus of this embodiment, and the rotation angle of a receiving antenna. The graph which shows an example of the measurement result of the characteristic which shows the relationship between the amplitude of the received signal after performing the synthetic aperture process in case the time diversity is not applied in the measuring apparatus of this embodiment, and the rotation angle of a receiving antenna. Explanatory drawing which shows an example of the received signal waveform explaining the cause of the increase in the relative received signal of a modulated wave in the measuring apparatus of this embodiment. Explanatory drawing of a received signal waveform when applying time diversity in the synthetic aperture process of the measuring apparatus of this embodiment. The graph which shows an example of the measurement result of the characteristic which shows the relationship between the amplitude of the received signal which applied the time diversity in the measuring apparatus of this embodiment, and performed the synthetic aperture process, and the rotation angle of a receiving antenna.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In this embodiment, incoming radio waves are measured using a synthetic aperture antenna. Synthetic aperture antennas measure the complex amplitude of radio waves while moving a small directional antenna (actual aperture antenna), record the measured value of the complex amplitude, and then calculate the measured complex amplitude of the received signal. On the other hand, it is a virtually large antenna formed by in-phase synthesis by signal processing. Since the synthetic aperture antenna has higher resolution than the real aperture antenna with respect to the arrival direction (DOA) of the incoming radio wave, the arrival time of a time-varying wave (for example, a modulated wave such as a fading wave) coming from an arbitrary direction can be obtained. Suitable for high angular resolution measurement of spatial profiles. In addition, since it is not necessary to arrange a plurality of large-size directional antennas having a desired angular resolution, a simple configuration can be achieved. Moreover, since it is not necessary to correct the amplitude and phase between cables that occur when using a plurality of antennas, measurement can be performed easily.

  Fig.1 (a) is explanatory drawing which shows an example of the measuring apparatus of the incoming radio wave using the synthetic aperture antenna which concerns on one Embodiment of this invention, FIG.1 (b) is the movement path | route of the receiving antenna of the measuring apparatus It is explanatory drawing which shows an example of (rotation locus | trajectory) C. The measuring apparatus 10 according to the present embodiment includes a receiving antenna 100 that can be driven to rotate, a reference antenna 200 that is fixedly arranged, and an antenna driving unit 300 that rotates the receiving antenna 100 so that the directionality of the receiving antenna 100 changes. A signal acquisition unit 400 that acquires signals received via the receiving antenna 100 and the reference antenna 200, a signal processing unit 500 that processes the signals acquired by the signal acquisition unit 400, and a control unit 600 that controls each unit, Is provided.

  The receiving antenna 100 is a directional antenna (for example, a horn antenna). The antenna drive unit 300 includes a turntable 310 on which the receiving antenna 100 is mounted, and a rotation drive unit 320 formed of a motor, a gear, or the like that drives the turntable to rotate.

  The receiving antenna 100 is attached at a distance R from the rotation center A of the turntable 310 so that the directionality of the receiving antenna 100 faces the radially outer side of the turntable 310. In this way, when the receiving antenna 100 is shifted from the rotation center A, when the wave source of the incoming radio wave is sufficiently far away, the amplitude pattern of the received signal (electric field) received by the receiving antenna 100 does not change, and the phase pattern changes significantly. .

  The distance R between the reception phase center B of the reception antenna 100 and the rotation center A of the turntable 310 may be set according to the wavelength (λ) of the incoming radio wave to be measured. The distance R may be set to about 1 to several tens of times the wavelength (λ) of the incoming radio wave. For example, R = 8λ to 18λ may be set.

  By rotating the turntable 310 with the rotation drive unit 320, the receiving antenna 100 is radially outward on a circular movement path (rotation locus) C that is separated from the rotation center A of the turntable 310 by a predetermined distance R. Rotate so that it moves with directivity facing.

  The reference antenna 200 is, for example, a horn antenna or an omnidirectional antenna.

  The signal acquisition unit 400 performs complex amplitude measurement using, for example, a 2-channel (2ch) vector receiver, receives a reception signal received via the rotationally driven reception antenna 100, and reception received via the fixedly arranged reference antenna 200. A signal (hereinafter also referred to as “reference signal”) is acquired.

  The signal processing unit 500 performs a synthetic aperture process based on the reception signal and the reference signal acquired by the signal acquisition unit 400 and the rotation angle of the reception antenna 100, and the signal after the synthetic aperture process and the rotation angle of the reception antenna 100 are The direction of incoming radio waves (DOA) is estimated based on the characteristic indicating the relationship.

  FIG. 2 is a flowchart showing an example of measurement of incoming radio waves in the measurement apparatus 10 of the present embodiment. In FIG. 2, first, the measurement apparatus 10 rotates the receiving antenna 100 and receives the received signal received via the receiving antenna 100 and the reference received via the reference antenna 200 at every predetermined rotation angle of the receiving antenna 100. A signal is acquired (S210). For example, the measurement apparatus 10 acquires a reception signal via each of the reception antenna 100 and the reference antenna 200 each time the reception antenna 100 is rotated by 1 ° or an angle smaller than 1 °.

  Next, the measuring apparatus 10 receives the reception signal and the reference signal acquired via the reception antenna 100 and the reference antenna 200 while the reception antenna 100 makes one rotation (360 ° rotation), and the reception antenna 100 at each acquisition time. Based on the rotation angle, a synthetic aperture process described later is performed (S220).

  Next, the measuring apparatus 10 determines the direction of the incoming radio wave based on a characteristic (hereinafter also referred to as “DOA spectrum”) indicating the relationship between the received signal after the synthetic aperture processing and the rotation angle (reception angle) of the receiving antenna 100. (DOA) is estimated (S230).

FIG. 3 is an explanatory diagram illustrating an example of the synthetic aperture processing of the received signal in the measurement apparatus of the present embodiment. In FIG. 3, the i-th rotation angle (hereinafter also referred to as “reception angle”) of the receiving antenna 100 is θ _i, and the j-th received signal (electric field) synthesized by the synthetic aperture processing of the reception angle θ _i is received. The angle difference between the rotation angle of the receiving antenna 100 and the reception angle θ _i (hereinafter also referred to as “combined rotation angle”) is φ _j . In addition, the number (number of elements) of reception signals (electric fields) synthesized by the synthetic aperture processing is 2N + 1 (N: natural number), and the radius of the moving path C at the reception phase center of the reception antenna 100 is R. The reception points (elements) of 2N + 1 angular differences φ _j (j = −N to + N) to be subjected to the synthetic aperture processing are respectively provided with symmetrical virtual arc array antenna elements constituting the synthetic aperture antenna. Can think.

The received signal (electric field) via the receiving antenna 100 is E _Rx (θ _i + φ _j ), the reference signal E _Ref (θ _i + φ _j ) received via the reference antenna 200, the wave number of the incoming radio wave is k, When the standard deviation of the window function of the synthetic aperture processing is σ, the received signal (electric field) E _SA (θ _i ) after the synthetic aperture processing at the reception angle θ _i of the incoming radio wave is calculated using the following equation (1). can do.

Here, the first factor E (θ _i + φ _j ) on the right side of the above equation (1) is the amplitude component (synthesis target amplitude component) of the relative reception signal of the j th synthetic aperture processing target at the i th reception angle. is there. The first factor E (θ _i + φ _j ) is the amplitude E _Ref (θ _i ) of the reference signal (electric field) received at the measurement point of the rotation angle (θ _i + φ _j ) of the receiving antenna 100 via the reference antenna 200. + Φ _j ) and the amplitude E _Rx (θ _i + φ _j ) of the received signal (electric field) via the receiving antenna 100, which is expressed by the following equation (2).

Further, the second factor exp {− (φ _j ² / 2σ ² )} on the right side of the above equation (1) is a weight to be given to the j-th synthesis target amplitude component E (θ _i + φ _j ). By giving this weight, it is possible to reduce unnecessary side lobes generated during measurement. Further, the beam width of the directional beam pattern of the synthetic aperture antenna can be changed, and a narrow beam pattern corresponding to the synthetic aperture can be formed.

Further, the third factor exp {jkR (1-cos (φ _j ))} on the right side of the above formula (1) is an arbitrary j (= −N based on the received signal at the j = 0th synthesis target center. This is the phase component of the received signal to be combined with (˜ + N) th.

The synthetic aperture processing at the reception angle θ _i of the incoming radio wave can be performed using the above formulas (1) and (2), and the received signal E _SA (θ _i ) after the synthetic aperture processing can be calculated. Based on the characteristic (DOA spectrum) indicating the relationship between the received signal E _SA (θ _i ) after the synthetic aperture processing and the rotation angle (reception angle) θ _i of the receiving antenna 100, the direction of the incoming radio wave (DOA) is simplified. And with high angular resolution.

FIG. 4 is a graph (see Non-Patent Document 1) showing an example of a simulation result in which the direction of incoming radio waves (DOA) is estimated by the synthetic aperture processing in the measurement apparatus of the present embodiment. A spectrum 401 in FIG. 4 is a characteristic showing a relationship between the amplitude E _SA (θ _i ) of the reception signal after the synthetic aperture processing and the rotation angle (reception angle) θ _i of the reception antenna 100. A spectrum 402 in FIG. 4 is a characteristic of a comparative example showing the relationship between the amplitude of the received signal measured without performing the synthetic aperture processing and the rotation angle (reception angle) θ _i of the receiving antenna 100. The characteristic of this comparative example corresponds to the distance R = 0 of the receiving antenna 100 from the rotation center A in the measurement apparatus of the present embodiment, and is a characteristic when a reception signal is acquired by rotating the receiving antenna at the rotation center A. is there. In FIG. 4, the 3 dB angular resolution in the direction of incoming radio waves (DOA) in the comparative example is 42.9 [°]. In contrast, the 3 dB angular resolution of the direction of incoming radio waves (DOA) measured by the measuring apparatus according to the present embodiment is 4.9 [°], and the direction of incoming radio waves (DOA) is estimated with high angular resolution. be able to. The 3 dB angular resolution is an angular width between points where the maximum amplitude of the received signal at the center in the direction of the incoming radio wave is attenuated by 3 dB.

  In addition, the measurement apparatus 10 of the present embodiment that rotates the reception antenna 100 to acquire a reception signal and performs synthetic aperture processing on the acquired reception signal is a combination of a conventional synthetic aperture antenna using a linear antenna array. Compared to the case, the angle dependency of the angle resolution of the arrival direction is low. In the case of a synthetic aperture antenna using a linear antenna array, the beam characteristics such as the main beam width and side lobe differ depending on the direction of the incoming radio wave, and the angle dependency of the angular resolution of the arrival direction is high.

  Further, unlike the case of the synthetic aperture antenna using the arc-shaped antenna array, the measurement apparatus 10 of the present embodiment does not require calibration between the antenna elements arranged in a circle, so that the direction of the incoming radio wave ( DOA) can be easily measured. In the case of a synthetic aperture antenna using an arc-shaped antenna array, a large number of antenna elements are arranged in a circle, and a symmetrical structure is formed using 2N + 1 antenna elements centered on antenna elements having directivity in the angle of incoming radio waves. In order to form an array antenna arranged in a circular arc shape, calibration between antenna elements is required.

  Next, application of time diversity to the received signal before the synthetic aperture processing in the measurement apparatus 10 of the present embodiment will be described.

  FIGS. 5 and 6 are characteristics (respectively) showing the relationship between the amplitude of the received signal and the rotation angle of the receiving antenna before and after the synthetic aperture processing when time diversity is not applied in the measurement apparatus 10 of the present embodiment. It is a graph which shows an example of the measurement result of (DOA spectrum). In the measurement of this example, a vector signal generator (Tx) as a wave source of an incoming radio wave is arranged at a position away from the measuring device 10 in the direction where the reception angle θ is 0 ° in the anechoic chamber, and the measurement parameters shown in Table 1 are used. The original was used. In addition, the receiving antenna 100 is installed at a radius R from the center of the turntable 310. Since the radius R of the virtual arc array antenna, which is the radius of the moving path C of the receiving antenna 100, was set to 64 cm, the beam width of the virtual arc array antenna was about 3 °.

In this measurement example, the reception antenna 100 is rotated in the range of the reception angle θ of −180 ° to + 180 ° to receive the incoming radio wave, and the measurement reception signal (electric field) E (θ _i + φ _j ) is acquired. Then, the synthetic aperture processing is performed using the above equation (1). In this measurement example, since a two-channel vector receiver and a vector signal generator are used, the received signal measured by the reference antenna 200 fixed at the same position as the measurement apparatus as in the above equation (2). By dividing (electric field), a measurement reception signal (measurement electric field) E (θ _i + φ _j ) to be processed by the synthetic aperture is obtained.

In the measurement result of the relative reception signal (reception signal of the reception antenna / reference signal of the reference antenna) E (θ _i + φ _j ) before application of the synthetic aperture processing in FIG. 5, the reception angle θ is in the range of −180 ° to −60 °. Within the range of + 60 ° to + 180 °, there is an angle θ where the relative received signal of the modulated wave whose amplitude varies with time is higher than the vicinity of the wave source direction (reception angle θ is near 0 °). On the other hand, in the direction of the wave source where the reception angle θ is 0 °, it is unlikely that a strong spectrum with a high relative reception signal will occur.

  In the measurement result (DOA spectrum) of the relative received signal after application of the synthetic aperture processing in FIG. 6, both the modulated wave whose amplitude varies with time and the unmodulated continuous wave whose amplitude does not vary with time (hereinafter referred to as “CW”). The wave source direction (the direction of arrival of incoming radio waves) can be accurately detected. However, when the reception angle θ indicated by the alternate long and short dash line in the figure is in the range of 40 ° to 100 °, the spectrum 601 of the modulated wave is 10 dB or more higher than the spectrum 602 of the CW, and the dynamic range when measuring the modulated wave is large. Since it deteriorates, the possibility of erroneous detection in the direction of the wave source (the direction of arrival of incoming radio waves) increases.

  FIG. 7 is an explanatory diagram illustrating an example of a received signal waveform that explains the cause of an increase in the relative received signal of the modulated wave in the measurement apparatus of the present embodiment. A black circle in FIG. 7 is a reception point of incoming radio waves. As shown in FIG. 7, the modulation wave may fluctuate with time, and the reference signal (electric field) that is the received signal of the reference antenna 200 may be greatly reduced instantaneously like a measurement point surrounded by a one-dot chain line in FIG. 7. is there. Since the reference signal of the reference antenna 200 becomes the denominator of the equation (2) used for the calculation of the relative reception signal, the reception angle θ in FIG. It is considered that an increase in the relative measurement signal occurred within the range of 100 °. In addition, since the phase pattern of the received signal at each reception angle is disturbed due to a decrease in the reference signal received by the reference antenna 200, the synthetic aperture processing is not appropriately performed, and the dynamic range during modulation wave measurement may be deteriorated. .

  Therefore, in the measurement apparatus 10 of the present embodiment, the time diversity exemplified below is applied so that the synthetic aperture processing is appropriately performed even if there is an instantaneous decrease in the reference signal received by the reference antenna 200. Yes.

FIG. 8 is an explanatory diagram of received signal waveforms when time diversity is applied in the synthetic aperture processing of the measurement apparatus 10 of the present embodiment.
In the present embodiment, complex amplitude measurement is performed a plurality of times in each of a plurality of movement measurement angle ranges ψ _k (k = 1 to M) having a predetermined angular width that is continuous on the movement path (rotation locus) C of the receiving antenna 100. (2K + 1 times, K: natural number), and a plurality of sets of each of the received signal via the receiving antenna 100 and the reference signal via the reference antenna 200 are acquired. Here, M is the number of movement measurement angle ranges included in one rotation of the receiving antenna 100. For example, when the angular width of the moving measurement angle range is 1 °, M = 360. K is a parameter that defines the number of acquisitions of the received signal and the reference signal within each movement measurement angle range. For example, when K = 1, the reception signal and the reference signal are acquired 3 (= 2K + 1) times within each movement measurement angle range.

In the example of FIG. 8, the complex amplitude measurement is performed three times during the movement measurement angle range ψ _{k in which} the reception antenna 100 rotates by 1 °, and three sets of reception signals and reference signals are acquired. Further, the center of each of the mobile measurement angle range [psi _k is a target reception angle by 1 °, 2 single receiver angles away a predetermined angle on both sides from the target reception angle is added reception angle. The angle difference between the target reception angle and the additional reception angle can be arbitrarily set under the condition that the additional reception angle is located within the movement measurement angle range ψ _k , for example, 0.2 ° to 0.3 ° (see FIG. In the example of 8, it is 0.25 °).

In the time diversity of the present embodiment, for each of the plurality of movement measurement angle ranges ψ _k , the reference signal having the largest amplitude among the three reference signals E _Ref acquired within the movement measurement angle range ψ _k is used as the reference for the synthetic aperture processing target. Select as signal. For example, in the moving measurement angle range ψ ₀ in FIG. 8, the reference signal on the left side is selected because the reference signal at the measurement point on the left side of the center is the largest. In the moving measurement angle range ψ ₁ in FIG. 8, the reference signal on the right side is selected because the reference signal at the measurement point on the right side of the center is the largest.

In the time diversity of the present embodiment, for each of the plurality of movement measurement angle ranges ψ _k , the reception signal obtained through the reception antenna 100 acquired at the same timing as the selected reference signal is selected as the reception signal for the synthetic aperture processing target. To do. Further, the rotation angle (= target rotation angle θ + correction angle Δθ) of the reception antenna 100 corresponding to the selected reference signal and reception signal is used.

  In this embodiment, the synthetic aperture processing is performed based on the received signal and reference signal of each of the plurality of moving measurement ranges selected by applying the time diversity and the rotation angle of the receiving antenna 100 (the angle of the virtual array antenna). The direction of the incoming radio wave is estimated based on the characteristic (DOA spectrum) indicating the relationship between the received signal after the synthetic aperture processing and the rotation angle (θ + Δθ) of the receiving antenna 100.

  Note that, by using the time diversity, an error (angle difference Δθ) occurs between the angle of the measurement point of the signal used for the synthetic aperture processing and the angle of the virtual array antenna. The influence on the measurement accuracy due to the error (angle difference Δθ) is small, and synthetic aperture processing can be performed.

FIG. 9 shows an example of the measurement result of the characteristic (DOA spectrum) indicating the relationship between the amplitude of the received signal and the rotation angle of the receiving antenna 100 that have been subjected to the synthetic aperture processing by applying time diversity in the measuring apparatus 10 of the present embodiment. It is a graph which shows. A spectrum 901 in FIG. 9 shows a relationship between the amplitude E _SA (θ _i ) of the received signal and the rotation angle (reception angle) θ _i of the receiving antenna 100 when the synthetic aperture processing is performed by applying time diversity. It is a characteristic. A spectrum 902 in FIG. 9 shows a relationship between the amplitude E _SA (θ _i ) of the received signal and the rotation angle (reception angle) θ _i of the receiving antenna 100 when the synthetic aperture processing is performed without applying time diversity. It is a characteristic.

It can be seen from FIG. 9 that the dynamic range around the reception angle of ± 180 ° is improved by applying time diversity. When the time diversity is not applied, the fluctuation range of the amplitude pattern of the reference signal received by the reference antenna 200 is about −40 dB at the maximum. As shown in the above equation (2), the reception level E _Ref of the reference signal received by the reference antenna 200 is used as a denominator, and the reception level E _RX of the reception signal of the reception antenna 100 is calculated as a numerator. For this reason, in the comparative example in which the time diversity indicated by the spectrum 902 in FIG. 9 is not applied, the reception amplitude E _Ref of the reference antenna 200 is lower than the reception amplitude E _RX of the reception antenna 100, and the relative received signal to be subjected to the synthetic aperture processing The reliability of (E _RX / E _Ref ) drops, and the synthetic aperture processing (array synthesis) cannot be performed normally. On the other hand, in the vibration pattern of the reference antenna 200 when the time diversity shown by the spectrum 901 in FIG. 9 is applied, the fluctuation range of the reception level E _Ref of the reference signal is suppressed to within 10 dB at most angles. For this reason, the reliability of the relative received signal (E _RX / E _Ref ) to be subjected to the synthetic aperture processing is improved, and the synthetic aperture processing (array synthesis) can be performed normally, so that the dynamic range is considered to be improved.

  As described above, according to the present embodiment, by applying time diversity, it is possible to avoid an abnormal increase in the relative received signal used for the synthetic aperture processing, so that the reception intensity of the incoming radio wave coming from an arbitrary direction can be reduced. Even when the time fluctuates, the arrival direction (DOA) of the incoming radio wave can be easily measured with high angular resolution, and the measurement accuracy of the arrival direction can be increased. Further, the abnormal behavior of the DOA spectrum is reduced, and the possibility of erroneous detection of the direction of the incoming radio wave (the direction of the wave source) is reduced. In addition, in a dynamic environment (an environment in which Rayleigh fading occurs), it becomes possible to measure a spatiotemporal profile such as the direction of arrival of an incoming radio wave by a synthetic aperture antenna.

  Note that the time diversity method applied to the synthetic aperture processing in the above embodiment is not limited to that shown in FIG. For example, the following time diversity processing may be performed. In another example of the time diversity processing, the reception antenna 100 is stopped every time it moves a predetermined angle (for example, 1 °), and the complex amplitude measurement is performed a plurality of times during the stop, and the reception signal and the reference antenna via the reception antenna 100 are measured. A plurality of sets of reference signals via 200 are acquired. Then, the reference signal having the largest amplitude among the plurality of reference signals via the reference antenna 200 is selected as the reference signal to be subjected to the synthetic aperture processing. A reception signal via the reception antenna 100 acquired at the same timing as the selected reference signal is selected as a reception signal to be subjected to the synthetic aperture processing (reception signal at the angle of the virtual array antenna).

  In addition, the processing steps and the components of the measurement apparatus (antenna drive unit, signal acquisition unit, signal processing unit, control unit) described in this specification can be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof. For example, the processing in the measurement apparatus according to the present embodiment is realized by a predetermined program being read and executed in hardware described later or a predetermined program pre-installed in hardware described later is executed. The

  For hardware implementation, means such as processing units used to implement the steps and components in the entity (e.g., controller or signal processor) may be one or more application specific ICs ( ASIC), digital signal processor (DSP), digital signal processor (DSPD), programmable logic device (PLD), field programmable gate array (FPGA), processor, controller, microcontroller, microprocessor, electronic device May be implemented in other electronic units, computers, or combinations thereof designed to perform the functions described herein.

  Also, for firmware and / or software implementation, means such as processing units used to implement the above components may be programs (eg, procedures, functions, modules, instructions) that perform the functions described herein. , Etc.). In general, any computer / processor readable medium that specifically embodies firmware and / or software code is means such as a processing unit used to implement the steps and components described herein. May be used to implement For example, the firmware and / or software code may be stored in a memory, for example, in a control device, and executed by a computer or processor. The memory may be implemented inside the computer or processor, or may be implemented outside the processor. The firmware and / or software code may be, for example, random access memory (RAM), read only memory (ROM), nonvolatile random access memory (NVRAM), programmable read only memory (PROM), electrically erasable PROM (EEPROM) ), FLASH memory, floppy disk, compact disk (CD), digital versatile disk (DVD), magnetic or optical data storage, etc. Good. The code may be executed by one or more computers or processors, and may cause the computers or processors to perform the functional aspects described herein.

  Also, descriptions of embodiments disclosed herein are provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. The present disclosure is therefore not limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

DESCRIPTION OF SYMBOLS 10 Measuring apparatus 100 Reception antenna 200 Reference antenna 300 Antenna drive part 310 Turntable 320 Rotation drive part 400 Signal acquisition part 500 Signal processing part 600 Control part

Claims (14)

A measuring device for measuring incoming radio waves,
A receiving antenna having directivity;
An antenna driver for moving the receiving antenna;
A fixedly arranged reference antenna;
In each of a plurality of continuous movement measurement ranges in the movement path of the reception antenna, a reception signal received via the reception antenna at a plurality of different movement positions in the movement measurement range or one movement position in the movement measurement range. And a signal acquisition unit for acquiring a plurality of sets of reference signals received via the reference antenna;
For each of the plurality of movement measurement ranges, time diversity is applied to the plurality of sets of reception signals and reference signals acquired within the movement measurement range to select reception signals and reference signals to be subjected to synthetic aperture processing, and the time diversity is selected. The synthetic aperture processing is performed based on the received signal and the reference signal of each of the plurality of moving measurement ranges selected by applying and the rotation angle of the receiving antenna, and after the synthetic aperture processing in each of the plurality of moving measurement ranges And a signal processing unit that estimates a direction of the incoming radio wave based on a characteristic indicating a relationship between a received signal and a rotation angle of the receiving antenna. The measuring apparatus according to claim 1.
The time diversity processing applied by the signal processing unit synthesizes a reference signal having the largest amplitude among a plurality of reference signals acquired through the reference antenna for each of the plurality of movement measurement ranges. A measuring apparatus that is selected as a reference signal to be subjected to aperture processing, and that selects a received signal via the reception antenna acquired at the same timing as the selected reference signal as a received signal to be subjected to synthetic aperture processing. . The measuring apparatus according to claim 1.
The time diversity processing applied by the signal processing unit is stopped every time the reception antenna is moved by a predetermined angle, and during the stop, the reception signal via the reception antenna and the reference signal via the reference antenna are A plurality of sets are acquired, a reference signal having the largest amplitude among a plurality of reference signals via the reference antenna is selected as a reference signal for a synthetic aperture process, and the receiving antenna acquired at the same timing as the selected reference signal The measurement apparatus is a process for selecting the received signal as a received signal to be subjected to the synthetic aperture processing. In the measuring apparatus in any one of Claims 1 thru | or 3,
For each of the plurality of movement measurement ranges, the signal processing unit uses a reference signal selected by applying the time diversity as a denominator, and receives a reception signal via the reception antenna acquired at the same timing as the selected reference signal. A measuring apparatus for deriving a signal of the synthetic aperture processing target as a molecule. The measuring device according to claim 4.
The signal processing unit multiplies the synthetic aperture processing target signal by a weight determined based on the standard deviation of the synthetic aperture processing window function, and the synthetic aperture processing signal based on the synthetic aperture processing target signal multiplied by the weight. A measuring apparatus that performs processing. In the measuring apparatus in any one of Claims 1 thru | or 5,
The measurement apparatus characterized in that the antenna driving unit rotationally drives the receiving antenna so as to move in a state where directivity is directed radially outward on a circular moving path away from the rotation center. The measuring device according to claim 6.
The rotation angle of the reception antenna at the i-th measurement point where the synthetic aperture processing is performed is defined as a reception angle θ _i, and the j-th synthesis among a plurality of synthetic aperture processing target signals synthesized at the measurement point of the reception angle θ _i. The receiving antenna rotation angle (θ _i + φ _j ) selected by applying the time diversity is defined as φ _j , where the angular difference between the receiving antenna θ _i corresponding to the aperture processing target signal and the receiving angle θ _i is φ _j . The received signal and the reference signal in FIG. 4 are respectively E _Rx (θ _i + φ _j ) and E _Ref (θ _i + φ _j ), the number of elements of the synthetic aperture processing is 2N + 1 (N: natural number), and the movement of the receiving antenna When the radius of the path is R, the wave number of the incoming radio wave is k, and the standard deviation of the window function of the synthetic aperture processing is σ,
A measurement apparatus that calculates the reception signal E _SA (θ _i ) after the synthetic aperture processing at the reception angle θ _i using the following formulas (1) and (2).

A measurement method for measuring incoming radio waves,
Moving a directional receiving antenna;
In each of a plurality of continuous movement measurement ranges in the movement path of the reception antenna, a reception signal received via the reception antenna at a plurality of different movement positions in the movement measurement range or one movement position in the movement measurement range. Acquiring a plurality of sets of reference signals received via a fixedly arranged reference antenna;
For each of the plurality of movement measurement ranges, time diversity is applied to the plurality of sets of reception signals and reference signals acquired within the movement measurement range to select reception signals and reference signals to be subjected to synthetic aperture processing, and the time diversity is selected. The synthetic aperture processing is performed based on the received signal and the reference signal of each of the plurality of moving measurement ranges selected by applying and the rotation angle of the receiving antenna, and after the synthetic aperture processing in each of the plurality of moving measurement ranges Estimating the direction of the incoming radio wave based on a characteristic indicating a relationship between a received signal and a rotation angle of the receiving antenna. The measurement method according to claim 8, wherein
In the time diversity processing, for each of the plurality of movement measurement ranges, the reference signal having the largest amplitude among the plurality of reference signals acquired through the reference antenna within the movement measurement range is used as a reference signal to be subjected to synthetic aperture processing. And measuring the received signal via the receiving antenna acquired at the same timing as the selected reference signal as a received signal to be subjected to the synthetic aperture processing. The measurement method according to claim 8, wherein
The time diversity processing is stopped every time the reception antenna is moved by a predetermined angle, and during the stop, a plurality of sets of reception signals via the reception antenna and reference signals via the reference antenna are acquired, A reference signal having the largest amplitude among a plurality of reference signals via the reference antenna is selected as a reference signal to be subjected to the synthetic aperture processing, and a reception signal obtained via the reception antenna obtained at the same timing as the selected reference signal is synthesized. A measurement method characterized by selecting as a reception signal to be subjected to aperture processing. In the measuring method in any one of Claims 8 thru | or 10,
For each of the plurality of movement measurement ranges, a reference signal selected by applying the time diversity is used as a denominator, and a received signal via the reception antenna acquired at the same timing as the selected reference signal is used as the numerator. A measurement method characterized by deriving a signal to be processed. The measurement method of claim 11,
Multiplying the synthetic aperture processing target signal by a weight determined based on the standard deviation of the window function of the synthetic aperture processing, and performing the synthetic aperture processing based on the synthetic aperture processing target signal multiplied by the weight. Characteristic measuring method. In the measuring method in any one of Claims 8 thru | or 12,
The measurement method, wherein the receiving antenna rotates so as to move in a state in which directivity is directed radially outward on a circular moving path away from a rotation center. The measurement method of claim 13,
The rotation angle of the reception antenna at the i-th measurement point where the synthetic aperture processing is performed is defined as a reception angle θ _i, and the j-th synthesis among a plurality of synthetic aperture processing target signals synthesized at the measurement point of the reception angle θ _i. The receiving antenna rotation angle (θ _i + φ _j ) selected by applying the time diversity is defined as φ _j , where the angular difference between the receiving antenna θ _i corresponding to the aperture processing target signal and the receiving angle θ _i is φ _j . The received signal and the reference signal in FIG. 4 are respectively E _Rx (θ _i + φ _j ) and E _Ref (θ _i + φ _j ), the number of elements of the synthetic aperture processing is 2N + 1 (N: natural number), and the movement of the receiving antenna When the radius of the path is R, the wave number of the incoming radio wave is k, and the standard deviation of the window function of the synthetic aperture processing is σ,
A measurement method characterized in that the received signal E _SA (θ _i ) after the synthetic aperture processing at the reception angle θ _i is calculated using the following equations (1) and (2).

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