Method and system for detecting radio wave sources

Abstract

This invention provides a method and system for detecting unknown radio wave sources for radio wave users. [Solution] The present invention relates to a detection method for detecting an unknown radio wave source using a drone. In this detection method, the peak direction θa with the greatest intensity is detected from the radio wave signal received when a drone 200A equipped with a directional receiving antenna is rotated at a known first measurement position, and the peak direction θb with the greatest intensity is detected from the radio wave signal received when a drone 200B equipped with a directional receiving antenna is rotated at a known second measurement position, and the position of the radio wave source is calculated based on the first and second measurement positions and the peak directions θa and θb.

Description

Technical Field

[0001] The present invention relates to detecting an unknown radio wave source using an unmanned aircraft or unmanned aerial vehicle (hereinafter referred to as a drone) capable of remote operation or automatic control.

Background Art

[0002] In recent years, drones have been used for inspections of structures (such as towers and electric wires), delivery of goods, spraying of pesticides and fertilizers, reconnaissance, etc. Drones generally include components such as a battery, a motor, a propeller, a receiver, and a flight controller. The flight controller drives the propeller via the motor based on an instruction (radio wave) from a transmitter received by the receiver, and controls the attitude and speed of the aircraft.

[0003] For example, Patent Document 1 discloses a radio wave measurement system that uses an airborne object such as a drone to measure radio waves radiated by an antenna with high precision by eliminating the influence of multipath and the like. Further, Patent Document 2 discloses a wireless relay device that mounts a relay station on a drone and transmits radio waves from a directional antenna toward the ground.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the use of radio waves (carriers) in the air or above is permitted, users of these radio waves will need to know about unknown sources of radio waves. In addition to radio waves emitted by base stations used by high-performance mobile devices such as smartphones, radio waves from wireless signals such as Wi-Fi and Bluetooth used by businesses and homes, radio waves from wireless signals used by vehicles, and radio waves generated with the intention of intentionally interfering with wireless communications may also exist on the ground. Therefore, when using radio waves in the air or above, it is necessary to know what kinds of radio waves can be used at a given point or area in the air, in other words, to know about unknown sources of radio waves. Furthermore, it is desirable that the methods or systems for identifying unknown sources of radio waves avoid complexity and be low-cost.

[0006] The present invention aims to solve these conventional problems and to provide a method and system for detecting unknown radio wave sources for radio wave users. [Means for solving the problem]

[0007] The detection method according to the present invention detects an unknown radio wave source using at least a first and a second drone, and involves rotating a first drone equipped with a directional antenna at a known first measurement position to measure radio wave signals, detecting a first direction with the greatest radio wave signal strength based on the measurement results, rotating a second drone equipped with a directional antenna at a known second measurement position to measure radio wave signals, detecting a second direction with the greatest radio wave signal strength based on the measurement results, and calculating the location of the radio wave source based on the first and second measurement positions and the first and second directions.

[0008] Furthermore, the detection method according to the present invention uses a drone to detect an unknown radio wave source. When a drone equipped with a directional antenna is rotated at a known measurement position, the peak intensity at which the signal strength is maximum and the peak direction of the peak intensity are detected from the radio wave signal received by the antenna, and the position of the radio wave source is calculated based on the measurement position, the peak intensity, and the peak direction.

[0009] Furthermore, the detection method according to the present invention uses a drone to detect an unknown radio wave source, and measures the radio wave signal with an omnidirectional antenna mounted on the first drone at a known first measurement position, detects the first direction in which the radio wave signal strength is greatest based on the measurement results, measures the radio wave signal with an omnidirectional antenna mounted on the second drone at a known second measurement position, detects the second direction in which the radio wave signal strength is greatest based on the measurement results, and calculates the position of the radio wave source based on the first and second measurement positions and the first and second directions.

[0010] The detection system for detecting unknown radio wave sources according to the present invention includes a first drone equipped with a directional receiving antenna, a second drone equipped with a directional receiving antenna, and an electronic device capable of communicating with the first and second drones. The first drone detects the first direction with the greatest intensity from the radio wave signals received when rotated at a known first measurement position and transmits the detected first direction to the electronic device. The second drone detects the second direction with the greatest intensity from the radio wave signals received when rotated at a known second measurement position and transmits the detected second direction to the electronic device. The electronic device calculates the location of the radio wave source based on the first and second measurement positions and the received first and second directions.

[0011] Furthermore, the detection system for detecting unknown radio wave sources according to the present invention includes a drone equipped with a directional receiving antenna and an electronic device capable of communicating with the drone. The drone, at a known measurement position, detects the peak intensity at which the signal strength is maximum and the peak direction of the peak intensity from the radio wave signal received when the drone is rotated, transmits the detected peak intensity and peak direction to the electronic device, and the electronic device calculates the location of the radio wave source based on the measurement position, the received peak intensity, and the peak direction.

[0012] Furthermore, the detection system for detecting unknown radio wave sources according to the present invention includes a first drone equipped with an omnidirectional receiving antenna, a second drone equipped with an omnidirectional receiving antenna, and an electronic device capable of communicating with the first and second drones. The first drone detects the first direction with the greatest intensity from radio wave signals measured at a known first measurement position and transmits the detected first direction to the electronic device. The second drone detects the second direction with the greatest intensity from radio wave signals measured at a known second measurement position and transmits the detected second direction to the electronic device. The electronic device calculates the location of the radio wave source based on the first and second measurement positions and the received first and second directions. [Effects of the Invention]

[0013] According to the present invention, the location of an unknown radio wave source can be easily detected by using a drone equipped with a directional receiving antenna. According to the present invention, the location of an unknown radio wave source can be easily detected by using a drone equipped with an omnidirectional receiving antenna. [Brief explanation of the drawing]

[0014] [Figure 1] This figure shows the overall configuration of a radio wave source detection system using a drone according to an embodiment of the present invention. [Figure 2] This is a block diagram showing the electrical configuration of a radio wave source detection system using a drone according to an embodiment of the present invention. [Figure 3]It is a diagram showing a configuration example of a detection system according to a first embodiment of the present invention. [Figure 4] It is a diagram showing an operation flow of a detection system according to a first embodiment of the present invention. [Figure 5] It is a diagram schematically showing a peak direction where the intensity of the received radio wave signal is maximum. [Figure 6] It is a diagram showing a calculation example of the position of a radio wave source using triangulation according to a first embodiment of the present invention. [Figure 7] It is a diagram showing a storage example of a detection result of a radio wave source according to a first embodiment of the present invention. [Figure 8] It is a diagram showing a calculation example of a radio wave source according to a modification of a first embodiment of the present invention. [Figure 9] It is a diagram showing a configuration example of a detection system according to a second embodiment of the present invention. [Figure 10] It is a diagram showing an operation flow of a detection system according to a second embodiment of the present invention. [Figure 11] It is a diagram showing a calculation example of the position of a radio wave source according to a second embodiment of the present invention. [Figure 12] It is a diagram showing a configuration example of a detection system according to a third embodiment of the present invention.

Mode for Carrying Out the Invention

[0015] The present invention relates to a system for detecting an unknown radio wave source using a drone. It should be noted that the drawings referred to in the following description are exaggerated for easy understanding of the invention and do not represent the actual sizes and shapes of products, parts, etc. as they are.

Examples

[0016] Next, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a diagram showing the overall configuration of a radio wave source detection system using a drone according to an embodiment of the present invention. The detection system 100 of this embodiment comprises one or more electric drones 200 and a user terminal 300 capable of remotely controlling the drones 200. The user terminal 300 may directly transmit and receive wireless signals with the drones 200, or it may transmit and receive wireless signals via a network NW.

[0017] The drone 200 includes a main body 202, a plurality of support members 204 connected to the main end 202, and a plurality of propellers 206 connected to the ends of the support members 204. Inside the main body 202 are a camera 210, electronic components mounted on a circuit board, a battery, etc. A directional antenna 220 for receiving radio waves is also attached to the main body 202. The antenna 220 is used to detect unknown radio wave sources. The propellers 206 are driven by a motor (not shown), which is powered by electricity from the battery.

[0018] The drone 200 is capable of sending and receiving wireless signals to and from the user terminal 300 via a transmitting and receiving unit. For example, it can receive signals for flight control from the user terminal 300 or transmit video signals captured by the camera 210 to the user terminal 300.

[0019] Figure 2 is a block diagram showing the electrical configuration of the detection system in this embodiment. The drone 200 is composed of a radio wave receiving unit 230 that receives radio waves via a directional antenna 220, a frequency analysis unit 240 that analyzes the frequency of the radio waves received by the radio wave receiving unit 230, a GPS receiving unit 250 that detects the position of the drone 200, a controller 260, a geomagnetic sensor 270 that detects the orientation of the drone 200, a memory 280 that stores various data, and a transmitting / receiving unit 290 for sending and receiving data to and from the user terminal 300.

[0020] The antenna 220 is not limited in shape, type, or size, but is a directional receiving antenna, and the type of antenna used depends on the application and frequency band. Compared to an omnidirectional antenna, a directional antenna 220 has a relatively high gain (high sensitivity) for radio waves received from a specific direction, and a relatively low gain (low sensitivity) for radio waves received from other directions. The antenna 220 is attached, for example, to the approximate center of the main body 202 of the drone 200 via an axis 220a extending in the Z direction. A rotation mechanism for adjusting the orientation and angle of the antenna 220 is not essential; in this embodiment, the orientation of the antenna 220 is adjusted by rotating the drone 200. As will be described later, the antenna 220 is used to detect unknown radio wave sources, and the smaller the range of directivity, i.e., the range of the specific direction in which the gain is high, the better the accuracy of detecting unknown radio wave sources.

[0021] The radio wave receiving unit 230 receives radio wave signals received from the antenna 220. The radio wave receiving unit 230 may include an amplifier to amplify the radio wave signals, a frequency converter to convert high frequencies of the received radio wave signals to lower frequencies, a filter to remove unwanted frequencies, and an A / D converter to convert the received radio wave signals into digital signals.

[0022] Furthermore, the radio wave receiving unit 230 includes a frequency analysis unit (spectrum analyzer) 240 that analyzes the frequency components of the received radio wave signal. The frequency analysis unit 240, for example, extracts signals of a specific frequency band from the radio wave signal received by the antenna 220 via a filter, and performs signal processing to analyze the signal strength of each frequency component of the extracted signal using algorithms such as Fourier transform. The results analyzed by the frequency analysis unit 240 are provided to the controller 260.

[0023] The controller 260 controls the overall operation of the detection system 100. The controller 260 is configured using hardware and / or software resources. For example, the controller 260 includes a microcontroller or microprocessor including ROM / RAM, which executes a program stored in the ROM / RAM to control the operation of the detection system 100.

[0024] When the controller 260 detects an unknown radio wave source, it stops the drone 200 at the measurement location, then rotates the drone 200, measuring the radio waves via the antenna 220 during the rotation. The measurement results are stored in the memory 280 or transmitted in real time to the user terminal 300 via the transceiver 290.

[0025] The geomagnetic sensor 270 detects the orientation of the drone 200 and provides the detection result to the controller 260. When the controller 270 detects an unknown radio wave source, it stops the drone at the measurement location based on the three-dimensional position information detected by the GPS receiver 250, and controls the attitude of the drone 200 so that it faces the reference direction based on the orientation detected by the geomagnetic sensor 270.

[0026] The memory 280 can store data and software applications required by the controller 260, or measurement results of radio signals. The transmitting / receiving unit 290 transmits and receives signals to and from the user terminal 300 via a transmitting / receiving antenna separate from the antenna 220. Alternatively, the transmitting / receiving unit 290 may be connected to the user terminal 300 via a wire, in which case, after the drone 200 stops flying, the measurement results of radio signals stored in the memory 280 can be provided to the user terminal 300. Furthermore, the transmitting / receiving unit 290 may transmit radio signals directly to the user terminal 300, or it may transmit radio signals to the user terminal 300 via a relay station or network.

[0027] The user terminal 300 is not particularly limited, but it is configured using electronic devices such as a multi-functional communication terminal like a smartphone, a mobile communication terminal, or a notebook or laptop computer device equipped with communication functions.

[0028] The user terminal 300 is configured to include, for example, an input unit 310, an output unit 320, a communication unit 330, a storage unit 340, and a control unit 350. The input unit 310 receives instructions from the user and provides them to the control unit 350. The output unit 320 may include a display unit such as a screen or an audio output unit such as a speaker. The communication unit 330 transmits and receives signals with the transceiver unit 290 of the drone 200. The storage unit 340 stores programs and data necessary for controlling the drone 200, as well as programs and data for detecting the location of unknown radio wave sources. The control unit 350 remotely controls the drone 200 via the communication unit 330 based on instructions input from the input unit 310 and programs stored in the storage unit 340, and also detects the location of unknown radio wave sources from measurement results received from the communication unit 330.

[0029] Next, the details of the radio wave source detection system according to the first embodiment of the present invention will be described. As shown in Figure 3, the detection system 100A according to the first embodiment comprises two drones 200A and 200B and an electronic device 300A as a user terminal.

[0030] Figure 4 shows the operation flow of the detection system of the first embodiment. First, drone 200A is flown to the first measurement position, and drone 200B is flown to the second measurement position, and the attitude of drones 200A and 200B is controlled so that they are stationary at the first and second measurement positions, facing approximately horizontally in the reference direction (S100).

[0031] In one embodiment, drones 200A and 200B are flown to the first and second measurement positions by remote control from the electronic device 300A (S100). The control unit 350 transmits an aerial control signal including the first and second measurement positions to drones 200A and 200B via the communication unit 330. Drones 200A and 200B calculate their current position based on the GPS signal received by the GPS receiver 250 and fly to the first and second measurement positions. The first measurement position (X1, Y1, z) and the second measurement position (X2, Y2, z) are set to the same height z. When drones 200A and 200B arrive at the first and second measurement positions, their attitude is controlled based on the measurement results of the geomagnetic sensor 270 so that they face the reference bearing and are horizontal. The reference direction is arbitrary, but for example, drones 200A and 200B are adjusted to face north (0 degrees).

[0032] In another embodiment, the drones 200A and 200B may be controlled to autonomously navigate toward the first and second measurement positions based on flight information stored in memory 280, where they will remain stationary in a horizontal position and face the reference bearing. The following operations of the drones 200A and 200B may be performed by remote control from the electronic device 300A as described above, autonomous control by programs installed on the drones 200A and 200B themselves, or joint control between the electronic device 300A and the drones 200A and 200B.

[0033] Next, at the first and second measurement positions, the drones 200A and 200B are simultaneously rotated in the XY plane at time t while maintaining a horizontal position (S110). For example, when the electronic device 300A transmits information about the first and second measurement positions to the drones 200A and 200B, it can include time information related to the measurement time t. Alternatively, time information related to the measurement time t is stored in the memory 280 of the drones 200A and 200B. The drones 200A and 200B are rotated at least once, i.e., 360 degrees, while maintaining a horizontal attitude. The antenna 220 is attached near the center of the drones 200A and 200B, and when the drones 200A and 200B are rotated once, the antenna 220 measures radio wave signals from all directions in the XY plane of the drones 200A and 200B. If an unknown radio wave source exists, the directional antenna 220 measures a relatively large signal strength in a specific direction during rotation.

[0034] Next, the radio wave receiving units 230 of the drones 200A and 200B receive radio signals via the antenna 220 while the drones are rotating. Since the received radio signals reflect a superposition of various signals, the frequency analysis unit 240 analyzes the frequency components of the received radio signals and measures the signal strength for each frequency (S120). The strength of the received radio signals is a function of the rotation angle of the drones 200A and 200B. In other words, if an unknown radio wave source is emitting radio waves, the strength of the radio signal received by the radio wave receiving unit 230 increases when the drones 200A and 200B are rotated in the direction of the radio wave source.

[0035] Figure 5(A) schematically shows the relationship between the rotation angle of drone 200A and the strength of the received radio signal, where the signal strength is at its maximum (peak) when the rotation angle of drone 200A is θa. Figure 5(B) schematically shows the relationship between the rotation angle of drone 200B and the strength of the received radio signal, where the signal strength is at its maximum (peak) when the rotation angle of drone 200B is θb. Hereafter, the rotation angles θa and θb at which the signal strength is maximum will be referred to as the peak direction (rotation angles θa, θb = peak direction θa, θb).

[0036] The frequency analysis unit 240 analyzes the intensity of the radio wave signal received during rotation for each frequency and provides the analysis results to the controller 260. Based on the analysis results from the frequency analysis unit 240, the controller 260 detects the peak azimuths θa and θb of the drones 200A and 200B at which the radio wave signal intensity is maximum (S130). The peak azimuths θa and θb are the rotation angles from the reference azimuth in the XY plane of the drones 200A and 200B located at altitude z. As shown in Figure 5(A), the peak azimuth θa, which is the rotation angle of the drone 200A at which the received radio wave signal intensity is maximum, is detected, and as shown in Figure 5(B), the peak azimuth θb, which is the rotation angle of the drone 200B at which the received radio wave signal intensity is maximum, is detected.

[0037] Next, the transmitting and receiving units 290 of the drones 200A and 200B transmit measurement information (including time information representing the measurement time t, if necessary) including the peak azimuths θa and θb related to the first and second measurement positions to the electronic device 300A (S140). The drones 200A and 200B may transmit the measurement information to the electronic device 300A in real time, or after the end of the flight, the drones 200A and 200B may transmit specific information stored in the memory 280 to the electronic device 300A via wireless communication or a wired cable. The communication unit 330 of the electronic device 300A receives the measurement information regarding the peak azimuths θa and θb from the drones 200A and 200B, and the control unit 350 calculates the position of the radio wave source based on the received measurement information (S150).

[0038] Figure 6 shows an example of calculating the position of a radio wave source using trigonometry. The first and second measurement positions are known, and the height z of the first and second measurement positions are equal. C1 and C2 are the rotation centers of drones 200A and 200B, and the peak azimuths θa and θb are the rotation angles in the XY plane from the reference azimuth. The control unit 350 of the electronic device 300A calculates the point K(Xk, Yk, z) where the peak azimuth θa from the first measurement position (X1, Y1, z) and the peak azimuth θb from the second measurement position (X2, Y2, z) intersect in the XY plane at height z. The position of the radio wave source may be estimated as the coordinates (Xk, Yk) at height z, or as the coordinates (Xk, Yk) at height z0. Height z0 is, for example, the height from the ground or the height of a building. The control unit 350 stores the calculated or estimated location of the radio wave source in the storage unit 340 as location information related to the first and second measurement locations (S160).

[0039] By performing the detection process described above at multiple measurement locations, a location map of radio wave sources can be generated. Figure 7 shows an example of such a location map. The location map includes location information of radio wave sources that generate frequency f at time t at the intersection of a matrix of first measurement locations P1, P2, P3, ..., Pn-1, Pn and second measurement locations Q1, Q2, Q3, ..., Qn-1, Qn. Such a location map can be used to identify usable radio waves in the air or above, or to identify jamming radio waves, etc.

[0040] The above-described method for detecting radio wave sources explains the case where the heights z of the first and second measurement positions are equal, but the heights of the first and second measurement positions may be different. An example of calculation in this case is shown in Figure 8. When the first measurement position is (X1, Y1, Z1) and the second measurement position is (X2, Y2, Z2), the control unit 350 calculates the difference ΔZ between the heights of the first and second measurement positions, and calculates the intersection point K of the peak azimuths θa and θb from the first and second measurement positions using trigonometry in the XY plane of Z1-ΔZ or Z2+ΔZ.

[0041] Furthermore, while the above embodiment shows an example of measuring radio waves when two drones 200A and 200B are rotated simultaneously, the method is not limited to this. For example, at time t1, drone 200A may be flown to a first measurement position, where the peak direction θa is detected from the radio waves received while it is rotating, and the detected peak direction θa is transmitted to the electronic device 300A. Then, at time t2, drone 200A may be flown to a second measurement position, where the peak direction θb is detected from the radio waves received while it is rotating, and the detected peak direction θb is transmitted to the electronic device 300A. The electronic device 300A may then calculate the position of the radio wave source from the peak direction θa at time t1 and the peak direction θb at time t2. In this case, detection errors may occur due to the time difference between t1 and t2, but it is possible to detect the position of the radio wave source using trigonometry with a single drone.

[0042] Next, a second embodiment of the present invention will be described. Figure 9 is a diagram showing the configuration of the detection system according to the second embodiment, and the same reference numerals are used for components identical to those in the first embodiment. The detection system 100B of the second embodiment consists of one drone 200A and an electronic device 300A. In the first embodiment, an example of detecting the location of an unknown radio wave source using two drones was described, but in the second embodiment, the location of an unknown radio wave source is detected using one drone 200A.

[0043] Figure 10 shows the operation flow of the detection system of the second embodiment. The drone 200A flies to the first measurement position (S200), as in the first embodiment, and there it analyzes the frequency of the radio wave signal received via the antenna 220 while rotating, measures the distribution of signal strength for each frequency (S210, S220), and detects the peak value F of the signal strength and the peak direction θa of the peak value F (S230). Next, the drone 200A transmits the peak value F and peak direction θa related to the first measurement position to the electronic device 300A (S240), and the electronic device 300A calculates the position of the radio wave source based on the measurement results from the drone 200A (S250), and stores the calculation result in the storage unit 340 (S260).

[0044] In the second embodiment, the position of the radio wave source is calculated from the peak value F and the peak azimuth θa. Figure 11 shows an example of calculating the position of the radio wave source according to the second embodiment. The first measurement position (X1, Y1, z) is known. The intensity of the radio wave signal radiated from the radio wave source is inversely proportional to the square of the distance as the distance from the radio wave source increases. From this relationship, the distance L corresponding to the peak value F is calculated. The method for calculating the distance L is not particularly limited, but the distance L may be calculated by calculation using a formula that represents the relationship between intensity and distance, or the distance L may be obtained by referring to a lookup table that represents the relationship between intensity and distance, which is prepared in advance. In this way, the control unit 350 of the electronic device 300A calculates the point K (Xk, Yk, z) with the peak azimuth θa and distance L from the first measurement position (X1, Y1, z) in the XY plane at height z. As in the first embodiment, the location of the radio wave source may be estimated as point K, or as coordinates (Xk, Yk) at height z0.

[0045] Thus, according to the second embodiment, the location of a radio wave source can be detected in a simple manner using a single drone.

[0046] Next, a third embodiment of the present invention will be described. In the first embodiment, an example was shown in which an unknown radio wave source was detected using two drones 200A and 200B, but in the third embodiment, an unknown radio wave source is detected using three or more drones.

[0047] Figure 12 shows the configuration of the detection system of the third embodiment. The detection system 100C of the third embodiment comprises N (where N is an integer of 3 or more) drones 200A, 200B, ..., 200N and an electronic device 300B that communicates with these drones. The N drones 200A, 200B, ..., 200N transmit measurement information, including N peak directions θa, θb, ..., θN detected at their respective measurement positions, to the electronic device 300B, and the electronic device calculates the position of the radio wave source based on the received measurement information. If there are multiple points where the N peak directions intersect, the electronic device 300B may, for example, calculate the center point or centroid of the multiple points and estimate this as the position of the radio wave source in the XY plane, or it may find a circle inscribed in the multiple points and estimate the center of this circle as the position of the radio wave source, or it may estimate the area surrounded by the multiple points as the position of the radio wave source. Thus, according to this embodiment, by using N drones, the accuracy of detecting the location of the radio wave source can be further improved.

[0048] Next, a fourth embodiment of the present invention will be described. While the first to third embodiments showed examples of measurements using a directional receiving antenna, the fourth embodiment uses an omnidirectional antenna instead of a directional antenna. Since an omnidirectional antenna has average receiving sensitivity in all directions, it is possible to receive radio waves from all directions.

[0049] For example, drones 200A and 200B are equipped with omnidirectional antennas. Drones 200A and 200B remain stationary at the first and second measurement positions, where they measure radio signals via the omnidirectional antennas. Rotation or circling of drones 200A and 200B is unnecessary during radio signal measurement. The radio signals received from the omnidirectional antennas reflect a superposition of various signals arriving from various directions. Drones 200A and 200B analyze the frequency components of the measured radio signals and detect the peak direction with the greatest signal strength from all frequency components, or, depending on the detection purpose, detect the peak direction with the greatest signal strength from a specific frequency band.

[0050] Omnidirectional antennas have average reception sensitivity across all directions, and their accuracy in detecting peak direction is not as good as that of directional antennas. Therefore, when using an omnidirectional antenna, it is desirable to perform measurements using N drones, as in the third embodiment.

[0051] Thus, according to the fourth embodiment, by using an omnidirectional antenna, it becomes unnecessary to rotate each drone at the measurement location, thereby shortening the radio wave measurement time and simplifying the measurement process.

[0052] Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, the drone is equipped with a drive mechanism for tilting the axis 220a of the antenna 220 with respect to the Z axis. The drive mechanism is not particularly limited, but includes, for example, a gear or link driven by a motor, and the drive mechanism adjusts the tilt angle of the axis 220a of the antenna 220 with respect to the Z axis. In the first embodiment, the axis 220a of the antenna 220 is parallel to the Z axis, and therefore radio wave signals in the XY plane are measured. However, in this embodiment, it is possible to measure radio wave signals in a plane corresponding to the tilt angle of the axis 220a of the antenna 220.

[0053] In the fifth embodiment, when measuring the radio wave signal, the tilt angle θ of the axis 220a of the antenna 220 is adjusted, and then the drone is rotated while maintaining a horizontal attitude. As a result, the radio wave signal is measured in a plane tilted by θ from the XY plane, and the peak direction is detected from the measurement result. The fifth embodiment can be used to estimate the position of the radio wave source in the Z direction. For example, by changing the tilt angle θ of the axis 220a of the antenna 220 to θ=0 degrees, θ=5 degrees, θ=10 degrees, θ=15 degrees, and θ=20 degrees, and measuring the radio wave signal at each tilt angle, the plane with the highest signal strength can be identified, thereby estimating the height of the radio wave source in the Z direction. The tilt angle θ can be transmitted to the drone along with the measurement position information when the electronic device 300A has the drone measure the radio wave signal.

[0054] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims. [Explanation of Symbols]

[0055] 100, 100A, 100B, 100C: Detection system 200, 200A, 200B, 200C: Drone 300, 300A: User terminal (electronic device) 220: Antenna 230: Radio wave receiving unit 240: Frequency Analysis Unit 250: GPS receiver 260: Controller 270: Geomagnetic sensor 280: Memory 290: Transmitter / Receiver

Claims

1. A detection method for detecting an unknown radio wave source using at least a first and a second drone, At a known first measurement position, a first drone equipped with a directional antenna is rotated to measure radio signals, and based on the measurement results, the first direction with the greatest radio signal strength is detected. At a known second measurement location, a second drone equipped with a directional antenna is rotated to measure radio signals, and based on the measurement results, the second direction with the strongest radio signal strength is detected. A detection method for calculating the location of a radio wave source based on first and second measurement positions and first and second azimuths.

2. The detection method according to claim 1, wherein the first drone and the second drone measure radio signals when they are rotated at the same time.

3. The detection method according to claim 1, wherein the heights of the first measurement position and the second measurement position are equal.

4. The detection method according to claim 1, wherein the location of the radio wave source is calculated based on the triangulation method.

5. The detection method according to claim 1, wherein the first and second directions are the rotation angles of the first and second drones when the intensity of the received radio signal is maximized.

6. A detection method that uses a drone to detect unknown radio wave sources, When a drone equipped with a directional antenna is rotated at a known measurement location, the peak intensity at which the signal strength is maximum and the peak direction of that peak intensity are detected from the radio signal received by the antenna. A detection method for calculating the location of a radio wave source based on the measurement position, the peak intensity, and the peak direction.

7. A detection method that uses a drone to detect unknown radio wave sources, At a known first measurement location, a radio signal is measured using an omnidirectional antenna mounted on the first drone, and based on the measurement results, the first direction with the greatest radio signal strength is detected. At a known second measurement location, the radio signal is measured using an omnidirectional antenna mounted on the second drone, and based on the measurement results, the second direction with the strongest radio signal strength is detected. A detection method for calculating the location of a radio wave source based on first and second measurement positions and first and second azimuths.

8. A detection system for detecting unknown radio wave sources, The first drone equipped with a directional receiving antenna, A second drone equipped with a directional receiving antenna, Includes an electronic device capable of communicating with the first and second drones, The first drone detects the first direction with the greatest intensity from the radio signal received when it is rotated at a known first measurement position, and transmits the detected first direction to the electronic device. The second drone detects the second direction with the greatest intensity from the radio signal received when it is rotated at a known second measurement position, and transmits the detected second direction to the electronic device. The aforementioned electronic device is a detection system that calculates the location of a radio wave source based on first and second measurement positions and first and second received directions.

9. The detection system further includes N drones (where N is an integer greater than or equal to 3), Each of the N drones detects the N directions with the greatest intensity from the radio signals received when rotated at a known measurement position, and transmits the detected N directions to the electronic device. The detection system according to claim 8, wherein the electronic device calculates the position of the radio wave source based on the N directions received.

10. The detection system according to claim 8, wherein each of the first and second drones is equipped with an adjustment function for adjusting the angle of the receiving antenna in the Z direction.

11. A detection system for detecting unknown radio wave sources, A drone equipped with a directional receiving antenna, Includes an electronic device capable of communicating with the drone, The drone, at a known measurement location, detects the peak intensity and the peak direction of the signal strength from the radio signal received when the drone is rotated. The detected peak intensity and peak orientation are transmitted to the electronic device. The aforementioned electronic device is a detection system that calculates the location of a radio wave source based on the measurement position, the received peak intensity, and the peak direction.

12. A detection system for detecting unknown radio wave sources, The first drone equipped with an omnidirectional receiving antenna, A second drone equipped with an omnidirectional receiving antenna, Includes an electronic device capable of communicating with the first and second drones, The first drone detects the first direction with the greatest intensity from the radio signal measured at a known first measurement position, and transmits the detected first direction to the electronic device. The second drone detects the second direction with the greatest intensity from the radio signal measured at a known second measurement position, and transmits the detected second direction to the electronic device. The aforementioned electronic device is a detection system that calculates the location of a radio wave source based on first and second measurement positions and first and second received directions.

13. The detection system further includes N drones (where N is an integer greater than or equal to 3), Each of the N drones detects the N directions with the greatest intensity from the radio signals measured at a known measurement location, and transmits the detected N directions to the electronic device. The detection system according to claim 12, wherein the electronic device calculates the position of the radio wave source based on the N directions received.

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