JP5339493B2 - Radio wave emission source visualization device and method - Google Patents

Description

  The present invention provides a radio wave emission source visualization device for outputting a two-dimensional arrival direction as a two-dimensional image such as an azimuth angle and an elevation angle of an arrival direction so that an emission source of an incoming radio wave can be easily identified, and the same Regarding the method.

  Conventionally, in order to specify a radio wave emission source, a directional antenna, an electric field probe, and the like and a receiver are used to search for a site where the reception level is maximum, so to speak, the radio wave emission source is specified by hand search. Also, in recent years, the arrival direction of radio waves is estimated using an arrival direction estimation device using an array antenna and the like, and has been located close to the emission source. However, it is still extremely difficult to identify the part or place emitting radio waves.

Patent Document 1 describes a method and apparatus for visualizing a wave source image by a radio holography method, but discloses a method and apparatus for easily identifying a radio wave emission source that is a subject of the present invention. It has not been.
JP 09-134113 A

  As described above, in the conventional radio wave emission source visualization device and method, it is still extremely difficult to specify the portion or place where the radio wave is emitted.

  The present invention has been made to solve the above-described problem. In order to easily identify the radio wave emission source visually, the radio wave emission which can be displayed in a more easily understandable manner by making the arrival direction estimation result into a two-dimensional image. It is an object to provide a source visualization apparatus and method.

  In order to solve the above problems, a radio wave emission source visualization apparatus and method according to the present invention include a reference antenna that receives incoming radio waves in the same frequency band and an array antenna formed by arranging a plurality of antenna elements on a plane. The reception output of each element of the array antenna is sequentially switched from the antenna device provided to be derived simultaneously with the reception output of the reference antenna, and the arrival direction of radio waves from the simultaneous output of each element output of the array antenna and the reference antenna And the direction-of-arrival estimation result converted into a two-dimensional image is output to the display unit. At this time, the captured image is superimposed on the arrival direction estimation result converted into a two-dimensional image and displayed with the camera facing the estimated radio wave arrival direction.

  The processing algorithm for estimating the direction of arrival employs a radio holography method.

  Therefore, according to the present invention, the radio wave emission source capable of displaying the direction-of-arrival estimation result in a two-dimensional image so that the radio wave emission source can be easily identified visually and displaying the camera image so as to be more easily understood. A visualization device and method thereof can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram schematically showing the configuration of a radio wave emission source visualization device according to an embodiment of the present invention. This apparatus includes a reference antenna 10, an array antenna 20, a frequency conversion unit 30, an AD conversion unit 40, an arrival direction estimation processing unit 50, an image composition processing unit 60, a display unit 70, and a camera unit 80.

  The reference antenna 10 and the array antenna 20 are receiving antennas that can measure the same frequency band. The array antenna 20 includes N antenna elements A11 to A1N arranged in a lattice pattern on a plane. The shape and type of antenna elements, the total number of antenna elements, the interval for arranging the antenna elements, and the like are to be measured. It is optional depending on the measurement purpose. In order to suppress the sensitivity of radio waves incident from the opposite side of the array surface, the plane on which the antenna elements A11 to A1N are arranged can be used as a reflector.

  Any one of the antenna elements A11 to A1N can be used as the reference antenna 10. In this case, there is an advantage that a mechanical structure for separately attaching the reference antenna 10 becomes unnecessary.

  The antenna switching unit 21 switches the antenna elements to be sequentially received in the array antenna 20 at a predetermined order and interval, and receives the received signal of the selected antenna element A1i (i is any one of 1 to N) as the reference antenna 10. Are derived simultaneously with the received signal. As described above, by simultaneously deriving from the reference antenna 10 and one of the selected antenna elements A11 to A1N, the received wave between the reference antenna 10 and the selected antenna element A1i in the subsequent arrival direction estimation process Can be detected.

  The frequency converter 30 amplifies the incoming radio wave and converts it to an intermediate frequency that can be AD-converted by the AD converter 40 at the subsequent stage. The AD converter 40 simultaneously samples and converts the received signals from the antenna elements A1i selected by the reference antenna 10 and the array antenna 20 into digital signals. The sampling timing and the switching timing of the antenna switching unit 21 are linked and controlled by the timing control unit 41. The data digitized by the AD conversion unit 40 is processed by the arrival direction estimation processing unit 50 and sent to the image composition processing unit 60.

  On the other hand, the camera unit 80 shoots with the camera imaging direction aligned with the antenna directivity direction. For example, the camera unit 80 is fixed to a base having the element arrangement surface of the array antenna 20, and the directivity direction of the array antenna 20 is substantially the center of the visual field of the camera. It is set to come to the part. The captured image of the camera unit 80 is sent to the image composition processing unit 60. The image composition processing unit 60 converts the arrival direction estimation result into a two-dimensional image, and displays the result on the display unit 70 so as to overlap the captured image from the camera unit 80.

  In the above configuration, the measurement is performed simultaneously with the reference antenna 10 and one of the selected antenna elements A11 to A1N, so that the reference antenna 10 and the antenna element A1i selected in the subsequent arrival direction estimation process are measured. The phase difference between received waves is detected. The arrival direction estimation processing unit performs arrival direction estimation processing by radio holography. FIG. 2 shows a processing flow of direction-of-arrival estimation processing by the radio holography method.

  In FIG. 2, in step S <b> 11, signals received by the reference antenna 10 and the antenna element A <b> 1 i are converted into digital data through the frequency conversion unit 30 and the AD conversion unit 40. When the number of antenna elements of the array antenna is N, N digital data of the reference antenna 10 and N digital data of the array antenna 20 are obtained. When the element number of the array antenna 20 is i = 1,..., N, the digital data of the reference antenna 10 and the digital data of the array antenna 20 are obtained for the element number i. The digital data per element is M samples.

  In step S12, the digital data obtained in step S11 is subjected to FFT (Fast Fourier Transform). Using the FFT result, a complex correlation value is calculated for the frequency range in which the direction of arrival is to be estimated.

  In step S13, a correlation matrix is obtained from the complex correlation value obtained in step S12. The correlation matrix is a mathematical matrix in which complex correlation values are arranged in the same arrangement as the physical arrangement of the array antenna 20.

  In step S14, the correlation matrix obtained in step S13 is zero-padded to obtain an extended correlation matrix. The extended correlation matrix is extended to a matrix of 256 × 256, for example.

  In step S15, a two-dimensional FFT is performed on the extended correlation matrix obtained in step S14. An arrival direction estimation result can be obtained by performing two-dimensional FFT. As the arrival direction estimation result, it is possible to obtain an estimated radio wave intensity for each arrival direction. It is estimated that there is a radio wave emission source in the direction where the estimated radio wave intensity is strong. In the two-dimensional FFT, for example, a one-dimensional FFT is first performed for every row, and then a one-dimensional FFT is performed for every column.

  The reason why the correlation matrix is the extended correlation matrix is to intentionally increase the number of samples when performing the two-dimensional FFT and improve the arrival direction estimation resolution.

  The image composition processing unit 60 creates a composite image by superimposing the arrival direction estimation result obtained by the arrival direction estimation processing unit 50 and the image captured by the camera unit 80. The azimuth and elevation angle corresponding to each pixel of the camera image is measured in advance, and the synthesized image is created by combining the elevation angle and azimuth angle of the arrival direction estimation result.

  Arrival direction estimation results are imaged by coloring each estimated radio wave intensity. There are various synthesis methods, but an example is shown below.

When creating a composite image, the color of the radio field intensity is added to the camera image at a certain rate. If the hue of the camera image is quantified with the three primary colors of red, green, and blue, and Rc, Gc, and Bc, respectively, and the colors of the arrival direction estimation results are Re, Ge, and Be, the combined colors R, G, and B are When the ratio is 7: 3, the result is as follows.
R = (7Rc + 3Re) / 10
G = (7Gc + 3Ge) / 10
B = (7Bc + 3Be) / 10
When the camera unit 80 is installed at a location away from the phase center of the antenna, an accurate composite image can be obtained by performing correction using parallax.

  According to the radio wave emission source visualizing device having the above configuration, the radio wave intensity for each direction of arrival of radio waves is imaged and combined with the camera image for display, so that the radio wave emission source can be easily identified. Will be able to.

  The present invention can be applied in various fields such as a radio wave monitoring field for the purpose of finding a source of illegal radio waves and an analysis of unnecessary radiation emitted from a device.

  In particular, in the direction-of-arrival estimation processing according to the present invention, since a two-dimensional FFT is used for two-dimensional visualization, processing can be performed at a higher speed than other generally known MUSIC methods and interferometry methods. (The MUSIC method and the interferometry method require scanning at fine angular intervals when detecting the direction of arrival, and thus require a large amount of calculation, and are not particularly suitable for two-dimensional visualization.)

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram which shows the structure of the radio wave emission source visualization apparatus of one Embodiment which concerns on this invention. The flowchart which shows the flow of a process of the arrival direction estimation process part shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Reference antenna, 20 ... Array antenna, A11-A1N ... Antenna element, 21 ... Antenna switching part, 30 ... Frequency conversion part, 40 ... AD conversion part, 50 ... Arrival direction estimation process part, 60 ... Image composition process part, 70: display unit, 80: camera unit.

Claims (4)

An antenna device including an array antenna formed by arranging a reference antenna that receives incoming radio waves in the same frequency band and a plurality of antenna elements on a plane;
Antenna switching means for sequentially switching the reception output of each element of the array antenna from the antenna device and deriving simultaneously with the reception output of the reference antenna;
Estimating the direction of arrival of radio waves from the simultaneous output of each element output of the array antenna and the reference antenna, and arrival direction estimation processing means for outputting a direction of arrival estimation result obtained by two-dimensional imaging,
An imaging camera for imaging the direction of arrival obtained by the direction-of-arrival estimation processing means;
The parallax of the captured image of the imaging camera with respect to the phase center of the array antenna is corrected , and the azimuth angle and elevation angle corresponding to each pixel of the captured image are measured. Image combining means for combining the azimuth angle and the elevation angle and combining the arrival direction estimation result and the captured image;
A radio wave emission source visualizing device comprising: display means for displaying a composite image generated by the image composition means.   The radio wave emission source visualization device according to claim 1, wherein the arrival direction estimation processing means employs a radio holography method as a processing algorithm.   The radio wave emission source visualization device according to claim 1, wherein the reference antenna is a part of an antenna element of the array antenna. The reception output of each element of the array antenna is sequentially switched from an antenna device including an array antenna formed by arranging a reference antenna that receives incoming radio waves in the same frequency band and a plurality of antenna elements on a plane, and the reference antenna The process of deriving simultaneously with the received output;
Estimating the direction of arrival of radio waves from the simultaneous output of each element output of the array antenna and the reference antenna, and outputting a direction of arrival estimation result obtained by two-dimensional imaging,
Imaging the direction of arrival obtained by the direction of arrival estimation process;
The parallax of the captured image with respect to the phase center of the array antenna is corrected , and the azimuth angle and elevation angle corresponding to each pixel of the captured image are measured. A process of synthesizing the arrival direction estimation result and the captured image by combining the angle and the elevation angle ;
And a step of displaying a composite image generated by the image composition.

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