JP2007017271A - Antenna inter-element phase correction mode electric wave emission source visualizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric wave emission source visualizer for enhancing estimation accuracy on an electric wave arrival direction by performing estimation on the arrival direction with data added thereto, the data being amplitude-phase characteristics tabulated as a correction data table on respective antenna elements of an array antenna. <P>SOLUTION: An output of the array antenna 11 for receiving an arrival electric wave is connected to a frequency conversion part 12 while an output of the conversion part 12 is connected to an A/D conversion part 13. An output of the conversion part 13 is connected to an electric wave emission source visualization processing operation part 14. Data on the phase-amplitude characteristics of the respective antenna elements of the array antenna 11 are previously stored and accumulated as the correction data table 16 in the operation part 14. The electric wave arrival direction is corrected by using correction data at an arrival frequency, and then, is displayed on a display device 15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus that can specify the position of an object that emits radio waves with high accuracy by using an arrival direction estimation technique of an incoming radio wave, a radio wave emission source visualization technique, and an antenna technique.

  With the spread of mobile communication systems and wireless LAN systems, problems such as radio wave interference due to radio wave interference and the need to detect illegal radio stations have arisen. In order to solve such a problem, an apparatus for identifying and visualizing a radio wave emission source is required.

  A radio wave emission source visualization device is a system that estimates the direction of arrival of radio waves by receiving radio waves with an array antenna with a plurality of antenna elements arranged on a flat surface and visualizing the radio waves using the received radio waves. is there. As a method for visualizing radio waves, a radio holography method as shown in Reference 1 is known. In the processing, the signal and signal phase information received by each antenna element are used. As a result, the estimation result of the radio wave arrival direction is displayed on the screen as an estimated value (elevation angle, azimuth angle).

  When there is no disturbance in the amplitude and phase information received by the array antenna, it is possible to accurately estimate the direction of arrival of radio waves, but when multiple antennas are close to each other, mutual impedance occurs between antenna elements, The phase and amplitude characteristics of the antenna change. This is called coupling between antenna elements.

An array antenna has a plurality of antenna elements arranged close to each other, and causes coupling between antenna elements between adjacent antenna elements, thereby generating amplitude and phase errors. In the prior art, the radio wave emission source is estimated on the assumption that there is no coupling between the antenna elements of the array antenna, and the amplitude and phase errors are the error factors for the estimation accuracy of the radio wave arrival direction. In particular, an offset error occurs in the central direction (center direction of the array antenna), which is a large error factor in the estimation accuracy of the radio wave arrival direction.
Japanese Patent Laid-Open No. 11-326480

  Accordingly, the present invention has been made in view of the above, and an object thereof is to store amplitude and phase information of each antenna element of the array antenna as a correction data table. When performing radio holography processing to determine the radio wave arrival direction, the radio wave arrival direction is estimated using the radio holography by referring to the correction data at the measurement frequency from this correction data table and estimating the radio wave arrival direction. An object of the present invention is to provide a radio wave emission source visualization device that can be improved.

In order to solve the above problem, in the antenna element phase correction method radio wave emission source visualization device, an array antenna that receives incoming radio waves,
A frequency converter that converts the radio frequency received by the antenna into a predetermined frequency;
An A / D converter that converts the analog signal converted by the frequency converter into a digital signal;
A radio wave emission source visualization processing calculation unit that calculates the position of the radio wave emission source from the signal A / D converted by the A / D conversion unit;
A display device that displays the output of the radio wave emission source visible processing arithmetic unit, and the antenna element of the array antenna by changing the frequency of radio waves coming from a direction perpendicular to the antenna plane in the radio wave emission source visual processing arithmetic unit A correction data table that measures the amplitude and phase characteristics of
When the direction of radio wave arrival is estimated, the correction data of the carrier center frequency of the radio wave received by the array antenna is extracted from the correction data table, and the correction data is multiplied by the uncorrected data to estimate the radio wave arrival direction. It is characterized by doing.

  In the above-mentioned radio wave emission source visualizing device between antenna elements of the present invention, a correction data table for correcting the estimation result of the arrival direction of radio waves can be created in the radio wave emission source visual processing calculation unit, and stored, stored and read out. It is characterized by being.

  According to the present invention, the amplitude and phase information of each antenna element of the array antenna is measured in advance by changing the frequency and stored as a correction data table. When estimating the direction of arrival of radio waves in radio holography, etc., it is possible to improve the estimation accuracy of the direction of arrival of radio waves by making corrections by referring to the correction data at the measurement frequency from the correction data table. is there.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a block diagram showing the configuration of a radio wave emission source visualization device according to an embodiment of the present invention, in which 11 is an array antenna, 12 is a frequency conversion unit, 13 is an A / D conversion unit, and 14 is radio wave emission source visualization processing. An arithmetic unit, 15 is a display device, and 16 is a correction data table.

  The output of the array antenna 11 that receives the incoming radio wave is connected to the frequency conversion unit 12, and the output of the frequency conversion unit 12 is connected to the A / D conversion unit 13. The output of the A / D conversion unit 13 is connected to the radio wave emission source visualization processing calculation unit 14. In the radio wave emission source visualization processing calculation unit 14, phase amplitude characteristic data of each antenna element of the array antenna 11 is stored and stored in advance as a correction data table 16, and the radio wave arrival direction is referred to with reference to the correction data at the arrival frequency. After correction, the image is displayed on the display device 15. The operation based on the above configuration will be described below.

Array antenna 11, for example, ^two N on the same plane T-type half-wave dipole antenna in the vertical and horizontal (N × NN is a positive integer) are arranged, the reference antenna is set at the center. The radio wave arrival direction can be calculated by comparing the amplitude and phase difference between the outputs of the reference antenna and the surrounding antennas and obtaining the direction in which the radio waves are strengthened most. This method is called radio holography.

  The radio wave received by the array antenna 11 is down-converted to a certain frequency (for example, 21.4 MHz) by the frequency changing unit 12 in order to match the processing method of the radio wave emission source visualization processing calculation unit 14 connected at a later stage. The A / D converter 13 converts the analog signal into digital using the output after frequency conversion. In the radio wave emission source visualization processing calculation unit 14, the phase amplitude characteristic data of each antenna element of the array antenna 11 is stored and stored in advance as a correction data table 16, and the data is read by reading the correction data at the frequency of the incoming radio wave. Correction processing is performed and the direction of arrival of radio waves is displayed on the display device 15.

  The correction data table 16 of the present invention will be described. Radio waves are radiated from a direction perpendicular to the center of the antenna plane while changing the frequency, and amplitude phase information of each antenna element is acquired in advance. The correction data table 16 shown in FIG. 2 indicates the frequency of radio waves vertically and the antenna element numbers in the array antenna 11 horizontally. Then, amplitude and phase characteristic data cal k (N) (k and N are positive integers) to be corrected of the measured radio wave are stored.

  An example of this correction data creation algorithm will be shown. Consider a case in which A / D conversion data having a center frequency fk is acquired using an array antenna having N antenna elements, and this A / D conversion data acquisition is repeated M times.

A / D conversion data (the number of samples is arbitrary) of the n-th antenna element is defined as ad (n). Fourier transform is performed on ad (n) and converted to frequency components. Let c (n) be the result of the conversion.

Thereafter, the band c (n) is added in accordance with the frequency band (center frequency fk, bandwidth: arbitrary (fh−fl), Nyquist frequency or less) at the time of estimating the radio wave arrival direction. The result of addition is e (n).

This is performed for all antenna elements (ad_1 to ad_N) and stored in an independent data area. Next, in order to increase the reliability of the correction data, the data acquisition (M times) is performed a plurality of times and added together. The result is E (n).

Then, the average of the number of data acquisition times is taken, and the result is set as correction data (ca1 (n)).

  This ca1 (n) is obtained at various center frequencies and stored as a correction data table.

  FIG. 2 explains the operation sequence in detail with reference to the processing flowchart of the present invention.

The radio wave to be measured is received by the array antenna 11. (S301)
The frequency changing unit 12 down-converts the signal to a certain frequency. (S302)
The A / D converter 13 converts an analog signal into digital. (S303)
(S302) and (S303) are performed to match the processing method in the radio wave emission source visualization processing calculation unit 14 connected in the subsequent stage.

The center frequency of the carrier of the incoming radio wave is determined by performing FFT (Fast Fourier Transform) on the A / D converted signal. (S304)
The correction data of the carrier center frequency is referred from the correction data table. (S305)
The data obtained by processing the A / D conversion data obtained here in the same manner using (Expression 1) and (Expression 2) described above is defined as e ′ (n).

Then, e ′ (n) is multiplied by the correction data referenced from the table. Let the result be cor (n).

Calculation of (Equation 5) is performed on all measured antennas, and the arrival direction of the radio wave is estimated by radio holography using cor (n). (S306)
By performing the above algorithm, the offset error can be reduced. (S307)
According to the inter-antenna element phase correction method radio wave emission source visualization apparatus according to the embodiment of the present invention configured as described above, the amplitude phase information of the antenna element is obtained when performing the radio wave arrival direction estimation process by radio holography or the like. By performing arithmetic processing using a correction data table that has been measured by changing the frequency in advance, it is possible to improve the estimation accuracy of the direction of arrival of radio waves.

  The present invention is not limited to the above-described embodiment as it is, and can be embodied without departing from the spirit of the invention at the stage of implementation.

It is a block diagram which shows the structure of the phase correction type | mold radio wave emission source visualization apparatus between antenna elements in one Example of this invention. It is an example of the correction | amendment data table of the phase correction type | formula radio wave emission source visualization apparatus between antenna elements in one Example of this invention. It is a flowchart which shows the process of the phase correction type | formula radio wave emission source visualization apparatus between antenna elements in one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Array antenna 12 ... Frequency conversion part 13 ... A / D conversion part 14 ... Radio wave emission source visualization process calculating part 15 ... Display apparatus 16 ... Correction data table

Claims (2)

An array antenna for receiving incoming radio waves,
A frequency converter that converts the radio frequency received by the antenna into a predetermined frequency;
An A / D converter that converts the analog signal converted by the frequency converter into a digital signal;
A radio wave emission source visualization processing calculation unit that calculates the position of the radio wave emission source from the signal A / D converted by the A / D conversion unit;
A display device for displaying the output of the radio wave emission source visual processing calculation unit;
In the radio wave emission source visible processing calculation unit, by changing the frequency of radio waves arriving from the direction perpendicular to the antenna surface, comprising a correction data table that measures in advance the amplitude phase characteristics of each antenna element of the array antenna,
When the direction of radio wave arrival is estimated, the correction data of the carrier center frequency of the radio wave received by the array antenna is extracted from the correction data table, and the correction data is multiplied by the uncorrected data to estimate the radio wave arrival direction. An antenna element phase correction method radio wave emission source visualization device characterized by:   The inter-antenna element phase correction method radio wave according to claim 1, wherein a correction data table for correcting the estimation result of the radio wave arrival direction is created in the radio wave emission source visual processing arithmetic unit, and can be stored, stored and read. Launch source visualization device.

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