JP2021119332A - Radio signal generation location estimation method - Google Patents

Abstract

To provide a method and system for estimating a radio signal generation location by a simpler configuration.SOLUTION: An interference source location estimation system 100 comprises: receivers 10A to 10D that receive an interference signal, and measure reception strength of the interference signal; and an interference source location estimation device 20. Three receivers of the receivers 10A to 10D are arranged on the same linear line. One receiver is arranged in a location off the linear line. The interference source location estimation device 20 is configured to receive data indicative of reception strength of the interference signal and reception time thereof from each of the receivers 10A to 10D, and estimate a generation location of the interference signal. The interference source location estimation device 20 is configured to estimate a distance difference corresponding to a difference between distances to two receivers from the generation location of the interference signal, from an attenuation characteristic of the interference signal on the basis of the location of each receiver and the data from each receiver. The interference source location estimation device 20 is configured to calculate at least three curves in which the distance difference stays fixed, and estimate a location where the at least three curves are convergent as the generation location of the interference signal.SELECTED DRAWING: Figure 1

Description

The present invention relates to methods and systems for estimating radio signal generation positions.

In a wireless system, an electromagnetic wave including a frequency that overlaps with the frequency of a radio wave used for transmission / reception may be received as an interference signal. The interference signal may affect the operation of the wireless system, and if the effect is serious, it is necessary to detect the interference signal and take countermeasures. To this end, a method of estimating the generation position of the interference signal has been proposed so far.

For example, in the method disclosed in Japanese Patent Application Laid-Open No. 2016-17887 (Patent Document 1), the absolute position of the source of interference is estimated based on the frequency of the signal. Japanese Unexamined Patent Publication No. 2015-732242 (Patent Document 2) discloses another method for estimating the position of an interference source. In this method, it is presumed that the interference source is located closer to the radio that has a smaller number of duplicate receptions than the radio that has a larger number of duplicate receptions due to data retransmission among the pair of radios.

In addition to the above method, there is a method of estimating the position of the interference source using, for example, a multi-beam antenna. Such an estimation method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-236707 (Patent Document 3), Japanese Patent Application Laid-Open No. 2009-206888 (Patent Document 4), and Japanese Patent Application Laid-Open No. 2008-216884 (Patent Document 5). There is.

Japanese Unexamined Patent Publication No. 2016-17887 Japanese Unexamined Patent Publication No. 2015-732242 JP-A-2009-236707 Japanese Unexamined Patent Publication No. 2009-206889 Japanese Unexamined Patent Publication No. 2008-216084

In the method disclosed in Japanese Patent Application Laid-Open No. 2016-17887 (Patent Document 1), a predetermined calculation is executed using signals in the 1.5 GHz band and the 11 GHz band. However, in the low frequency band, the accuracy of the above calculation decreases, and it is assumed that it becomes difficult to accurately estimate the position of the interference source.

With the method disclosed in Japanese Patent Application Laid-Open No. 2015-732242 (Patent Document 2), it is difficult to accurately estimate the position of the interference source when the number of stations is small. In other words, many stations need to be set up to implement this method.

It is low in the case of the estimation method as disclosed in JP-A-2009-236707 (Patent Document 3), JP-A-2009-206888 (Patent Document 4), and JP-A-2008-216884 (Patent Document 5). In terms of frequency, the antenna must be large. Therefore, it is not easy to carry out an estimation method using a multi-beam antenna in a low frequency band.

The present invention provides a method and a system for estimating a radio signal generation position with a simpler configuration.

The present invention, in one aspect, is a method of estimating the location of a radio signal, comprising arranging at least four receivers for receiving the radio signal. At least three of the at least four receivers are located on the same straight line, and at least one of the at least four receivers is located off the straight line. The estimation method includes a step in which each of at least four receivers receives a radio signal and transmits data indicating the reception time and reception strength of the radio signal to the estimation device, and the estimation device determines the position of each receiver. Based on the data from each receiver, the step of estimating the distance difference corresponding to the difference in distance from the position where the radio signal is generated to each of the two receivers from the attenuation characteristics of the radio signal, and the estimation device It includes a step of calculating at least three curves having a constant distance difference and estimating a position where at least three curves gather at a position where a radio signal is generated.

Preferably, the step of estimating the distance difference is at least the step of obtaining the attenuation characteristic of the radio signal based on the reception intensity in the receiver arranged on the straight line and the position with the receiver, and the step of estimating the attenuation characteristic. It includes a step of converting the difference in reception intensity at the same time between two of the four receivers into a distance difference.

Preferably, the step of estimating the distance difference is the step of determining the angle formed by the arrival direction of the radio signal with respect to the straight line by comparing the attenuation characteristic of the radio signal with the attenuation characteristic of the radio signal on the straight line, and the step on the straight line. Between each receiver based on the step of determining the sign of the angle by comparing the reception strength at the receiver with the reception strength at the receiver located off the straight line and the estimated arrival direction of the radio signal. Based on the comparison between the expected value of the difference in reception intensity and the measured value of the difference in reception intensity, the step of determining whether or not the measured value is appropriate, and the step of determining whether it is appropriate It includes a step of extracting the receiver from which the measured value is obtained as a reasonable measurement point.

Preferably, the step of measuring the reception intensity includes the step of simultaneously measuring the reception intensity in at least two of the four receivers, and one of the at least two receivers is of the reception intensity. It is set as a reference point that gives a standard.

The system for estimating the generation position of a radio signal according to a certain aspect of the present invention includes at least four receivers that receive the radio signal and measure the reception strength of the radio signal. At least three of the at least four receivers are located on the same straight line, and at least one of the at least four receivers is located off the straight line. The estimation system further includes an estimation device that estimates the generation position of the radio signal by receiving data indicating the reception time and reception intensity of the radio signal from each of at least four receivers. The estimation device is based on the position of each receiver and the data from each receiver, and from the attenuation characteristics of the radio signal, the distance difference corresponding to the difference in the distance from the position where the radio signal is generated to each of the two receivers. Is estimated, at least three curves with a constant distance difference are calculated, and the position where at least the three curves gather is estimated as the position where the radio signal is generated.

According to the present invention, the radio signal generation position can be estimated with a simpler configuration.

It is a figure which showed the structure for realizing the method of estimating the generation position of a radio signal according to one Embodiment of this invention. It is a block diagram which showed the structure of the receiver and the interference source position estimation apparatus used in the interference source position estimation system which concerns on this embodiment. It is a figure which showed the arrangement example of the measurement point. It is a schematic diagram which shows the measurement result of the reception intensity at a plurality of points. It is a figure which illustrated the timing of measurement at a plurality of measurement points. It is a schematic diagram which showed the relationship between the received power measured in the real environment, and the distance. It is a figure for demonstrating the relationship between the arrival direction of an interference wave, and the reception intensity at a measurement point. It is a figure explaining the method for narrowing down the arrival direction of an interference wave. It is a schematic diagram explaining the extraction of a reasonable measurement point. It is the figure which expressed the difference of the distance of the measurement point with respect to the interference source. It is a figure for demonstrating the estimation of the position of an interference source. It is a flowchart which showed the estimation method of the interference source which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

<Configuration for estimating the position of the interference source>
FIG. 1 is a diagram showing a configuration for realizing a method of estimating a generation position of a radio signal according to an embodiment of the present invention. In FIG. 1, the sensor 1 wirelessly transmits measurement data (data signal). The type of the sensor 1 is not particularly limited, but may be, for example, an observation station device used in a telemeter system. The type of the observation station device is not particularly limited, and may be, for example, a water level gauge, a rain gauge, a meteorological observation device, an atmospheric environment measurement device, or the like.

If there is a device that emits an electromagnetic wave including a frequency that overlaps with the frequency of the wireless system used by the sensor 1 for data transmission, the electromagnetic wave may cause radio wave interference with the sensor 1. In FIG. 1, a device that causes radio wave interference with the sensor 1 is represented as an interference source 50. When radio wave interference is caused by a radio signal (interference wave) generated from the interference source 50, for example, there is a concern that the transmission of the data signal from the sensor 1 may be interrupted intermittently. When the transmission of the data signal from the sensor 1 is interrupted, the measurement data at a certain time is lost on the side receiving the data signal.

In order to prevent such a problem, in the present embodiment, the position of the interference source 50, that is, the position where the radio signal is generated is estimated by the interference source position estimation system 100. The interference source position estimation system 100 includes receivers 10A, 10B, 10C, 10D and an interference source position estimation device 20. The receivers 10A, 10B, 10C, and 10D are receivers for receiving the interference signal. The interference source position estimation device 20 estimates the position of the interference source 50 based on the reception time and reception intensity of the interference signal at the receivers 10A to 10D.

When the interference occurs infrequently and irregularly, it is not easy to estimate the position of the interference source 50. In this embodiment, a plurality of receivers are installed. This makes it easier to estimate the position of the interference source 50. More specifically, in this embodiment, at least four receivers are used to estimate the location of the interference source 50. The reason for this will be described later.

As an example, the frequency band of the data signal is the VHF (Very High Frequency) band. Therefore, the interference source 50 also generates radio waves in the VHF band. However, this frequency band does not limit the scope of the present invention. Even if the frequency band of the data signal and the interference signal is a frequency band other than the VHF band, the interference source position estimation system 100 can be used to estimate the position of the interference source. Further, the type of the interference source 50 is not particularly limited.

FIG. 2 is a block diagram showing a configuration of a receiver and an interference source position estimation device used in the interference source position estimation system 100 according to the present embodiment. The receivers 10A to 10D shown in FIG. 1 all have the same configuration. Therefore, in FIG. 2, the receivers 10A to 10D are collectively referred to as the receiver 10.

The receiver 10 includes an antenna 11, an AD converter (ADC) 12, and a data logger 14.

The antenna 11 is an antenna for receiving an interference wave. The type of the antenna 11 is not limited as long as it is an omnidirectional antenna. As an example, for example, a discone antenna can be applied to the antenna 11. The discone antenna is suitably applicable to the present embodiment in that it has a wide usable frequency range and high sensitivity.

The AD converter 12 converts the received signal (analog signal) from the antenna 11 into a digital signal. As an example, an AD converter for a wireless communication signal can be applied to the AD converter 12.

The data logger 14 is a device that has a data recording and data transfer function, and can be realized by a PC (personal computer). The data logger 14 includes a calculation unit 15, a storage unit 16, and a communication unit 17.

The calculation unit 15 receives the digital data output from the AD converter 12. As a result, the calculation unit 15 can associate the reception intensity with the reception time. The storage unit 16 non-volatilely stores the reception time and reception intensity of the interference wave as log data.

The communication unit 17 transmits the reception time and reception intensity data (log data) stored in the storage unit 16 to the interference source position estimation device 20 through the communication network 30. The communication unit 17 may transmit data using wireless communication. Therefore, the communication network 30 may use, for example, the communication line of a mobile phone.

The receiver 10 (particularly the AD converter 12 and the data logger 14) is preferably small and lightweight. As a result, the burden required for the installation work of the receiver can be reduced, and the restriction on the installation location of the receiver 10 can be reduced.

The interference source position estimation device 20 can be realized by a computer and includes a communication unit 22 and a position estimation unit 24. The communication unit 22 receives data on the reception time and reception intensity of the interference wave from each receiver through the communication network 30. The communication unit 22 is connected to the communication network 30 by, for example, wirelessly. The position estimation unit 24 estimates the position of the interference source using the data from each receiver.

<Arrangement of measurement points>
Hereinafter, the position where the interference wave is measured is referred to as a “measurement point”. The position of the measurement point corresponds to the position of the receiver (particularly the installation position of the antenna).

FIG. 3 is a diagram showing an example of arrangement of measurement points. As shown in FIG. 3, in the present embodiment, the number of measurement points is at least four. Of at least four measurement points, at least three measurement points are arranged on the same straight line. At least one measurement point is off the straight line. The measurement points are arranged apart from each other by a distance that causes a significant difference in reception intensity.

FIG. 3A is a diagram showing an example in which the number of measurement points is four. The measurement points 5A, 5B, and 5C are arranged on the straight line L, and the measurement points 5D are located off the straight line L. FIG. 3B is a diagram showing an example in which the number of measurement points is five. The measurement points 5A, 5B, and 5C are arranged on the straight line L, and the measurement points 5D and 5E are located off the straight line L. The measurement points 5D and 5E are located on opposite sides of the straight line L.

Placing at least three measurement points on an exact straight line is not really easy. Therefore, whether or not at least three measurement points are on a straight line may be determined by whether or not the distance between the line and the measurement points is within a predetermined range.

At each measurement point, the receiver makes a wireless environment measurement. Specifically, the receiver repeats the peak holding measurement of the received power for a certain period of time (may be a short time). The receiver generates a log in which the time stamp of the measurement time is associated with the peak value of the received power for each measurement, and stores the log in the storage unit.

<Measurement of reception strength>
FIG. 4 is a schematic diagram showing the measurement results of the reception intensity at a plurality of points. At each receiver, the time of measurement and the spectrum are recorded. By measuring the reception intensity at a plurality of points, the reception level of the same interference wave is different. Therefore, this difference in reception level can be detected.

4 (a) and 4 (b) show schematic spectra of received power at two different measurement points (represented as measurement point 1 and measurement point 2), respectively. For example, the interference source position estimation device 20 collects the received data of each receiver and executes FFT (Fast Fourier Transform) on the received data, so that the frequency spectrum of the received power can be obtained. The FFT may be executed in each receiver 10 to obtain the frequency spectrum of the received power, and the result may be collected by the interference source position estimation device 20. The interference source position estimation device 20 can distinguish an interference wave from another signal (for example, a data signal shown in FIG. 1) by a frequency spectrum. As a result, the interference source position estimation device 20 can extract the received power of the interference wave received by each receiver.

In measuring the intensity of received power, it is preferable to set a reference point (1 point) and perform simultaneous measurement at at least 2 points including the reference point and other measurement points.

FIG. 5 is a diagram illustrating measurement timings at a plurality of measurement points. As shown in FIG. 5, for example, a measurement point 5A is set as a reference point. Received power is constantly measured at the reference point. Between the measurement points other than the reference point and the reference point, the relative difference in the reception level with the reception level at the reference point as the reference value can be found. Therefore, the measurements at the measurement points 5B, 5C, and 5D may be performed on different days. Even if the reception power is not measured at all the measurement points at the same time, the reception level at each measurement point at the same time can be obtained by using the relative difference of the reception levels.

空間伝搬係数ｎは無次元数である。ｎ＝２．０では、上記式は障害物のない理想空間での伝搬を表す。ｎ＜２．０であれば、上記式は、電波が反射しながら伝達するモデル（導波管など）を表し、ｎ＞２．０であれば、上記式は電波が障害物に吸収されて減衰しながら伝搬することを表わす。 <Attenuation of wireless signal>
In general, the relationship between distance and signal strength is described by the Friis transmission formula. Friis's transmission formula can generally be approximated by the following equation. Here L _B is the spatial path loss, lambda is the wavelength, D is distance, n represents a spatial propagation coefficients (transmission coefficient).

The spatial propagation coefficient n is a dimensionless number. At n = 2.0, the above equation represents propagation in an unobstructed ideal space. If n <2.0, the above equation represents a model (waveguide, etc.) that transmits radio waves while reflecting, and if n> 2.0, the above equation expresses that radio waves are absorbed by obstacles. Indicates that it propagates while decaying.

FIG. 6 is a schematic diagram showing the relationship between the received power measured in the actual environment and the distance. As shown in FIG. 6, when the signal attenuation (far) is converted into decibels (dB), the received power (unit: dB) is a straight line that changes with respect to the logarithmic distance on the graph unless it is in the immediate vicinity of the signal source. It can be regarded and expressed. The slope Do of the straight line is determined according to the frequency, and this frequency is a value determined based on the frequency spectrum of the interference wave. Therefore, Do is a known value obtained from the above formula and frequency.

In FIG. 6, the points on the straight line indicate that the reception result was good. On the other hand, when affected by shielding or the like, the point representing the reception result deviates below the straight line.

<Estimation of the direction of arrival of the interference wave>
FIG. 7 is a diagram for explaining the relationship between the arrival direction of the interference wave and the reception intensity at the measurement point. As shown in FIG. 7A, the positions of the measurement points 5A, 5B, and 5C are the points a, b, and c on the straight line L, respectively.

As shown in FIG. 6, the intensity (unit: dB) of the received power at the measurement points 5A, 5B, and 5C changes linearly with respect to the logarithm of the distance from the reference point according to the attenuation characteristics. Therefore, as shown in FIG. 7B, in the present embodiment, the attenuation characteristic is obtained based on the reception level difference of another measurement point with respect to the reception level of the reference point and the distance from the reference point. Further, the slope D of a straight line representing the damping characteristic is calculated.

The slope D of the straight line representing the attenuation characteristic depends on the angle θ formed by the arrival direction of the interference wave with respect to the straight line L. The direction of the interference source is as follows depending on the magnitude relationship between the inclination D and the inclination Do.

When D≈Do, θ = 0. That is, the interference source is in the extension direction of the straight line L.

When D <Do, the interference source is in the direction of θ = arccos (D / Do) with respect to the straight line L.

When D≈0, the interference source is in the direction of θ = 90 ° with respect to the straight line L.

In the graph shown in FIG. 7B, if the difference in reception level is not represented by a straight line and the center becomes large, it is estimated that the interference source is located near the point b (that is, near the measurement point 5B). Will be done.

In FIG. 7A, the interference wave is shown to arrive from the right side of the paper surface with respect to the straight line L. However, the interference wave may come from the opposite side (left side of the paper surface with respect to the straight line L). Therefore, in order to estimate the position of the interference source, it is necessary to specify from which side the interference wave comes from the left or right side with respect to the straight line L. By determining the sign of the angle θ, it is possible to specify from which side the interference wave comes from the left or right side with respect to the straight line L. In the following description, when the sign of the angle θ is positive, it is defined that the interference wave arrives from the direction on the right side of the straight line L.

FIG. 8 is a diagram illustrating a method for narrowing down the arrival direction of the interference wave. As shown in FIG. 8, the measurement points 5A, 5B, and 5C are located at points a, b, and c on the straight line L, respectively, and the measurement points 5D are located at points d off the straight line L.

The reception intensity at a point on the straight line L (for example, point b) is compared with the reception intensity at a point d not on the straight line L. When the reception intensity at the point d is larger than the reception intensity at the point b, it is estimated that the interference wave arrives from the side of the measurement point 5D (that is, the right side of the paper surface with respect to the straight line L). That is, θ> 0 (denoted as “+ θ” in FIG. 8). On the contrary, when the reception intensity at the point d is smaller than the reception intensity at the point b, it is estimated that the interference wave arrives from the side opposite to the measurement point 5D with respect to the straight line L (that is, the left side of the paper surface with respect to the straight line L). .. That is, θ <0 (denoted as “−θ” in FIG. 8).

<Extraction of appropriate measurement points>
As shown in FIG. 6, the plurality of measurement points may include measurement points in which the reception condition of the interference wave is not good due to the surrounding environment and the like. In order to estimate the position of the interference source more accurately, it is preferable to extract a measurement point from which a reasonable measurement result is obtained from a plurality of measurement points.

FIG. 9 is a schematic diagram illustrating the extraction of appropriate measurement points. Since the positional relationship between the measurement points is known with reference to FIG. 9, the distance between the measurement points is also known. Therefore, it is possible to predict the difference in reception level between a plurality of measurement points based on the attenuation characteristics. A measurement point with a small deviation between the expected reception level difference and the actual reception level difference is extracted as a valid measurement point. On the other hand, a measurement point having a large difference (deviation) between the expected reception level difference and the actual reception level difference is excluded from the estimation of the position of the interference source.

<Estimation of the position of the interference source>
FIG. 10 is a diagram showing the difference in the distance of the measurement points with respect to the interference source. In FIG. 10, each of points A and B is set as a valid measurement point. The difference in reception intensity between points A and B is β (dB).

The slope of the straight line representing the attenuation characteristic of the interference wave is D. There is a β / D difference between the distance from point A to the interference source and the distance from point B to the interference source. In this way, the difference β of the reception intensity between the points A and B can be converted into the difference (β / D) between the distance from the point A to the interference source and the distance from the point B to the interference source.

The source of interference is either on a curve that maintains a β / D distance from points A and B. Such a curve is a hyperbola, where points A and B correspond to the focal points of the hyperbola.

FIG. 11 is a diagram for explaining the estimation of the position of the interference source. As shown in FIG. 11, three valid measurement points are extracted (point A, point B and point C). A hyperbola is obtained based on two of the three measurement points. In FIG. 11, the hyperbola P1 is obtained from the points A and B, the hyperbola P2 is obtained from the points B and C, and the hyperbola P3 is obtained from the points C and A. The position where the hyperbola P1, the hyperbola P2, and the hyperbola P3 gather is presumed to be the position of the interference source 50.

If the number of valid measurement points is two, then there is one hyperbola. By having at least three reasonable measurement points, it is possible to obtain three or more hyperbolas, so that the position of the interference source 50 can be estimated. The number of reasonable measurement points may be 4 or more. The greater the number of valid measurement points, the more accurately the position of the interference source 50 can be estimated.

FIG. 12 is a flowchart showing a method of estimating an interference source according to the present embodiment. With reference to FIG. 12, in step S10, at least four receivers for receiving the interference wave are arranged. At least three of the at least four receivers are arranged on the same straight line L. On the other hand, at least one of the at least four receivers is arranged at a position deviating from the straight line L.

In step S20, each receiver receives the interference wave. As described above, it is not necessary for all receivers to receive the interference wave at the same time. At least two receivers may measure the reception intensity of the interference wave at the same time. One of these receivers is set at a reference point that gives a reference for reception strength. Each receiver transmits data indicating the reception time and reception intensity of the interference wave to the interference source position estimation device 20. As a result, the interference source position estimation device 20 acquires data from each receiver.

In step S30, the interference source position estimation device 20 acquires the attenuation characteristic of the interference wave. The interference source position estimation device 20 obtains the frequency spectrum of the interference wave from the data from each receiver. Based on the frequency spectrum, the interference source position estimation device 20 determines the frequency of the interference wave. From the frequency of the interference wave, the reception intensity at the measurement point arranged on the straight line L, and the position of the measurement point, the interference source position estimation device 20 calculates the slope D of the straight line representing the attenuation characteristic.

In step S40, the interference source position estimation device 20 estimates a distance difference corresponding to the difference in distance from the position where the interference signal is generated to each of the two receivers by using the calculated attenuation characteristic. Step S40 includes steps S41-S44.

In step S41, the interference source position estimation device 20 estimates the arrival direction of the interference wave. In this case, the interference source position estimation device 20 obtains the attenuation characteristic of the interference wave on the straight line L and calculates the slope Do. The slope Do is calculated from the above equation based on the frequency of the interference wave and the position of the measurement point. The interference source position estimation device 20 compares the inclination Do and the inclination D to obtain the magnitude relationship between the inclination Do and the inclination D. The interference source position estimation device 20 obtains the angle θ from the magnitude relationship between the inclination Do and the inclination D and the D / Do (see FIG. 7).

In step S42, the interference source position estimation device 20 narrows down the arrival direction. The interference source position estimation device 20 determines the sign of the angle θ based on the magnitude relationship between the reception level at the measurement point on the straight line and the reception level at the measurement point off the straight line. As a result, the interference source position estimation device 20 estimates from which side the interference wave is coming from the straight line L (see FIG. 8).

In step S43, the interference source position estimation device 20 extracts a reasonable measurement point. The interference source position estimation device 20 predicts the difference in reception level between the measurement points from the distance between the measurement points and the arrival direction of the interference wave. Then, a measurement point in which the difference between the expected reception level and the difference in the actual reception level is small is extracted as an appropriate measurement point. As described above, the interference source position estimation device 20 extracts three or more appropriate measurement points (see FIG. 9).

In step S44, the interference source position estimation device 20 uses the difference β of the reception intensity and the inclination D representing the attenuation characteristic to obtain the difference β of the reception intensity between the two measurement points from each measurement point to the interference source. Convert to distance difference β / D.

In step S50, the interference source position estimation device 20 calculates a hyperbola in which the difference in distance is β / D, focusing on the positions of the two measurement points. By selecting any two measurement points from three or more reasonable measurement points, the interference source position estimator 20 calculates at least three hyperbolas.

In step S60, the interference source position estimation device 20 estimates the position where the hyperbolas gather as the position of the interference source. If the plurality of hyperbolas do not intersect at one point, the interference source position estimation device 20 may estimate that the interference source is within a certain magnitude range (see FIG. 11).

For example, a VHF band wireless system is used for a communication line (telemeter line) such as disaster prevention radio, collection of weather monitoring information, or dam water discharge warning. Since the VHF band is a relatively low frequency band, it has a feature that the propagation loss is small. However, the antenna and the like become large, and the frequency of noise due to discharge or the like is often included in the VHF band. Therefore, it is assumed that radio wave interference will occur in the telemeter line.

Generally, the source (position) of radio waves is searched using a directional antenna. However, since the VHF band antenna is large, it is difficult to measure the interference wave in the field while holding it by hand. As another method, a method of estimating the source by the difference in the arrival time of radio waves is also known. However, this method requires high-precision time-synchronized measurement at multiple points at the same time.

According to this embodiment, the interference wave is measured at a plurality of points. By grasping the difference in reception intensity between the basic point and other measurement points, it is possible to estimate the position where the interference wave is generated without having to perform simultaneous measurement at all measurement points.

In addition, when communication is interrupted in the telemeter line due to interference, for example, it is dispatched to the site to capture the interference wave and elucidate the cause. However, since interference waves are often generated intermittently, it is possible that they will be dispatched to the site for a long period of time and many times in order to capture the interference waves and clarify the cause. This puts a strain on human resources. On the other hand, in the present embodiment, if a receiver is installed, the position of the interference source can be estimated basically by performing unmanned and automatic measurement. Therefore, it is possible to reduce the burden on equipment and personnel.

In addition, the receiver is configured to be portable. In addition, there are few restrictions on the installation location of the receiver. Therefore, a system for estimating the position of the interference source can be easily constructed.

Although embodiments of the present invention have been described, it should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is indicated by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

1 sensor, 2,11 antenna, 5A to 5E measurement points, 10,10A to 10D receiver, 12 AD converter, 14 data logger, 15 arithmetic unit, 16 storage unit, 17,22 communication unit, 20 interference source position estimation Device, 24 position estimation unit, 30 communication network, 50 interference source, 100 interference source position estimation system, points A, B, C, D, Do tilt, L straight line, P1 to P3 hyperbola, S10 to S60, S41 to S44 steps , A, b, c, d points.

Claims (5)

It is a method of estimating the position where a wireless signal is generated.
A step of arranging at least four receivers for receiving the radio signal is provided.
At least three of the at least four receivers are located on the same straight line, at least one of the at least four receivers is located off the straight line, and further. ,
A step in which each of the at least four receivers receives the radio signal and transmits data indicating the reception time and reception strength of the radio signal to the estimation device.
Based on the position of each receiver and the data from each receiver, the estimation device determines the distance from the generation position of the radio signal to each of the two receivers based on the attenuation characteristics of the radio signal. And the step of estimating the distance difference corresponding to the difference between
Generation of a radio signal, wherein the estimation device includes a step of calculating at least three curves having a constant distance difference and estimating a position where the at least three curves gather at the generation position of the radio signal. Position estimation method. The step of estimating the distance difference is
A step of obtaining the attenuation characteristic of the radio signal based on the reception intensity of the receiver arranged on the straight line and the position with the receiver.
The first aspect of the present invention includes a step of converting the difference in reception intensity at the same time between two receivers out of the at least four receivers into the distance difference based on the attenuation characteristics. The method for estimating the generation position of the radio signal described. The step of estimating the distance difference is
A step of determining the angle formed by the arrival direction of the radio signal with respect to the straight line by comparing the attenuation characteristic of the radio signal with the attenuation characteristic of the radio signal on the straight line.
A step of comparing the reception intensity of the receiver on the straight line with the reception intensity of the receiver at a position deviating from the straight line to determine the sign of the angle.
A step of predicting a difference in reception intensity between the receivers based on the estimated arrival direction of the radio signal, and
A step of determining whether or not the measured value is appropriate based on a comparison between the expected value of the difference in reception strength and the measured value of the difference in reception strength, and
The method for estimating a position where a radio signal is generated according to claim 2, further comprising a step of extracting a receiver for which an actually measured value determined to be valid is obtained as a valid measurement point. The step of measuring the reception intensity is
Including a step of simultaneously measuring the reception intensity in at least two of the at least four receivers.
The method for estimating a radio signal generation position according to any one of claims 1 to 3, wherein one of the at least two receivers is defined as a reference point that gives a reference for the reception strength. A receiver comprising at least four receivers for receiving a radio signal and measuring the reception strength of the radio signal.
At least three of the at least four receivers are located on the same straight line, and at least one of the at least four receivers is located off the straight line.
An estimation device for estimating the generation position of the radio signal by receiving data indicating the reception time and reception intensity of the radio signal from each of the at least four receivers is further provided.
The estimation device
Based on the position of each receiver and the data from each receiver, the attenuation characteristic of the radio signal corresponds to the difference in distance from the generation position of the radio signal to each of the two receivers. Estimate the distance difference and
Calculate at least three curves with a constant distance difference,
A system for estimating the generation position of a radio signal, which is configured to estimate the position where the at least three curves are gathered at the generation position of the radio signal.

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