JP2001059861A - Direction finding device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the arrival direction of electromagnetic waves accurately and speedily even in the case of low frequencies. SOLUTION: Scanning is performed by an antanna 11 of a directional rotating beam, and a beam waveform including the acquisition results of acquired electromagnetic waves is converted into an intermediate frequency and then converted into a direction finding signal waveform which indicates a maximum amplitude at the arrival direction of the electromagnetic waves at a direction finding waveform shaping part 13. The direction signal waveform is sampled at approximate cycles at an A/D converting part 14 and supplied for a first correlation processing part 18. In the first correlation processing part 18, with reference to a first reference waveform (16), the components of waveform changes in a unit of time are extracted and combined to create a first impulse response waveform which indicates a maximum peak value at the arrival direction. In a second correlation processing part 21, the azimuth direction is further limited (ϕ) with the arrival direction as a center to create a second impulse response waveform. As the impulse response waveform that indicates the arrival direction of electromagnetic waves is created by two stages in this way, it is possible to measure the arrival direction speedily and highly accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azimuth measuring apparatus and an azimuth measuring method for capturing an arriving electromagnetic wave by using an antenna for rotating or scanning a directional beam and measuring the azimuth of arrival of the electromagnetic wave. .

[0002]

2. Description of the Related Art In general, an azimuth measuring device which captures an electromagnetic wave arriving by an antenna for rotating a directional beam and measures the azimuth of arrival is obtained by rotating the antenna's rotating beam once in 360 degrees in the azimuth direction. The waveforms of the direction signals of the electromagnetic waves are as shown in FIGS. 7 and 8, respectively. The low-frequency reception electromagnetic waves have a gentle waveform in the direction of arrival as shown in FIG. As shown in FIG.

FIGS. 7 and 8 show the azimuth angle of the rotating beam on the horizontal axis and the signal level on the vertical axis. In any case, the arrival direction of the electromagnetic wave is the azimuth at which the electromagnetic wave is most strongly received. That is, the azimuth indicating the maximum peak value of the waveform.

In the method of automatically reading the arrival direction of an electromagnetic wave from the electromagnetic wave direction search signal waveform shown in FIGS. 7 and 8, a peak search process of the waveform is performed, and the maximum peak value is obtained from the search result. There is a method of determining the direction of arrival.

However, as shown in FIG. 8, when a high frequency electromagnetic wave is received, the waveform of the direction finding signal waveform becomes sharp at the maximum peak portion, so that it is relatively easy to obtain the direction of arrival. As the reception frequency becomes lower, as shown in FIG. 7, since the maximum peak portion becomes a gentle waveform, it is difficult to determine the azimuth at a low reception frequency, or even if it is determined, a large error tends to occur. Show.

In addition, even when the reception frequency is high, noise is often superimposed on the search signal waveform, and the waveform is disturbed, so that accurate azimuth determination has not been easy.

[0007] In order to automatically read the direction of arrival by relatively suppressing noise, another method is to sample the direction signal waveform in the direction of azimuth and then perform correlation processing with a reference pattern prepared in advance. A method of finding the direction at which the maximum peak value of the correlation value is obtained has been considered.

That is, the apparatus for measuring the azimuth by the correlation processing is configured as shown in FIG. 9, and specifies the rotating beam obtained from the antenna 11 with the reception unit 12 to determine the beam waveform including the result of capturing the electromagnetic wave for the reception processing. After being converted into the converted intermediate frequency signal, the direction-finding waveform shaping unit 13 shapes the direction-finding signal waveform, and the A / D conversion unit 14 samples the direction-finding signal waveform in the azimuth direction. At 15,
The correlation value between the reference pattern of the waveform prepared in advance by the reference waveform generation unit 16 and the digital search waveform from the A / D conversion unit 14 is extracted, and the signal processing unit 17 calculates the maximum peak value of the correlation value. It measures the arrival direction of the electromagnetic wave from the position.

Therefore, even in the correlation processing by the correlation processing unit 15 in FIG. 9, in the direction of arrival, if the reception frequency is low, a gentle direction search signal waveform as shown in FIG.
When the reception frequency is high, a sharp direction search signal waveform is obtained as shown in FIG. 11, but unlike the peak search process, a single waveform azimuth waveform with a relatively suppressed noise component is obtained. However, if the direction of arrival is to be measured with higher resolution and higher accuracy, the A / A
Since it is required that the sampling interval in the D conversion unit 14 be made finer, an increase in processing data in the correlation processing unit 15 cannot be avoided.

[0010]

As described above, according to the conventional azimuth measuring method, when the frequency of the arriving electromagnetic wave is low, the waveform of the direction signal becomes gentle, and the arriving azimuth can be determined with high accuracy. There is a problem that the measurement result of the direction of arrival tends to include a large error due to superposition of noise or the like.

Further, even when the direction of an incoming electromagnetic wave is measured by the correlation processing, the sampling interval needs to be reduced in order to obtain a more accurate direction measurement result. Becomes
There has been a problem that much time is required for arithmetic processing.

An object of the present invention is to provide an azimuth measuring apparatus and an azimuth measuring method capable of measuring the arrival azimuth of an electromagnetic wave more accurately and in a short time even when the direction signal waveform is gentle.

[0013]

Means for Solving the Problems The present invention is based on the following. In order to solve the above-mentioned conventional problems, a first invention is to rotate or scan a directional beam to capture an incoming electromagnetic wave, and a beam including a capture result obtained from the antenna. A receiving unit that converts a waveform into an intermediate frequency signal specified for reception processing, and a direction finding waveform shaping unit that shapes a direction finding signal waveform indicating the maximum amplitude in the arrival direction of the electromagnetic wave based on the converted output of the receiving unit. An A / D converter that performs A / D conversion on the direction signal waveform formed by the direction search waveform shaping unit at a first sampling period to generate a digital direction search waveform, and an A / D converter that is generated by the A / D converter. A first reference waveform for generating a first reference waveform having substantially the same frequency as the digital search waveform by indicating a maximum amplitude in a predetermined beam transmission initial direction of the antenna with respect to the digital search waveform A generating unit, based on said first reference waveform from the first reference waveform generator, combined extracts waveform change component per unit of the digital side probe waveform time,
A first correlation processing unit that generates a first impulse response waveform indicating a maximum peak value in the arrival direction of the electromagnetic wave by the correlation processing, and the first correlation processing unit that generates the first impulse response waveform.
The waveform change per unit time of the digital search waveform with respect to a predetermined azimuth range centered on the azimuth of the maximum peak value of the impulse response waveform based on the second reference waveform corresponding to the first reference waveform Extract and combine the ingredients,
A second correlation processing unit that generates a second impulse response waveform indicating a maximum peak value in the arrival direction of the electromagnetic wave by the correlation processing, and a second impulse response waveform shaped by the second correlation processing unit. A signal waveform processing unit for calculating the direction of arrival of the electromagnetic wave based on the signal waveform.

As described above, in the first invention apparatus, the first and second correlation processing units use the first reference waveform indicating the maximum amplitude in the predetermined beam transmission initial azimuth of the antenna, and the first reference waveform. With reference to a second reference waveform corresponding to the reference waveform,
Since the impulse response waveform showing the maximum peak value in the arrival direction of the electromagnetic wave is shaped by the correlation processing combining and extracting the waveform change components per unit time, the arrival direction of the electromagnetic wave is calculated. Thus, an impulse response waveform having a sharp peak and reducing the appearance of peaks other than the arrival direction is formed, and the arrival direction of the electromagnetic wave can be accurately obtained.

Further, in the apparatus of the present invention, a second correlation processing section is formed in addition to the first correlation processing section, and the second correlation processing section is provided within a predetermined azimuth range centered on the azimuth of the maximum peak value of the first impulse response waveform. On the other hand, since the correlation processing is performed using the second reference waveform as a reference, the first correlation processing unit obtains the arrival direction at a relatively coarse sampling interval over 360 degrees in the azimuth direction, and then the second correlation processing unit calculates the arrival direction. Finer correlation processing calculations can be performed in a narrow area centered on the direction of arrival, so the amount of calculation data for each correlation processor can be significantly reduced, and the direction of arrival can be found quickly. Can be.

According to a second aspect of the present invention, in the azimuth measuring method, a beam waveform including a capturing result obtained from an antenna for capturing an incoming electromagnetic wave is specified for reception processing by rotating or scanning a beam having directivity. After converting the signal into an intermediate frequency signal, a direction search waveform showing the maximum amplitude in the arrival direction of the electromagnetic wave is formed, and this direction search waveform is converted to A at the first sampling period.
After forming a digital search waveform by performing / D conversion, the maximum amplitude is obtained in the beam transmission initial direction of the antenna determined in advance, and a first reference waveform having substantially the same frequency as the digital search waveform is used as a reference. The first impulse response waveform having the maximum peak value in the arrival direction of the electromagnetic wave is shaped and generated by extracting and combining the waveform change components per unit time of the digital search waveform and performing the correlation process. For a predetermined azimuth range centered on the azimuth of the maximum peak value of the first impulse response waveform, a unit time of the digital search waveform is determined based on a second reference waveform corresponding to the first reference waveform. After extracting and combining the waveform change components of the above, a second impulse response waveform indicating the maximum peak value in the arrival direction of the electromagnetic wave is generated by the correlation process, and then the second impulse response waveform is generated. And measuring the arrival direction of the electromagnetic wave based on the pulse response waveform.

As described above, also in the second invention, the first invention
And a second correlation processing unit performs correlation processing in which a waveform change component per unit time is extracted and combined based on the first reference waveform and the second reference waveform, respectively.
Since the impulse response waveform showing the maximum peak value in the direction of arrival of the electromagnetic wave is shaped to calculate the direction of arrival of the electromagnetic wave, the appearance of waveform peaks other than the direction of arrival is reduced, and the direction of arrival of the electromagnetic wave is measured with higher accuracy. be able to.

Further, in the apparatus of the present invention, since the second correlation processing is performed in addition to the first correlation processing, the first correlation processing section obtains the arrival direction at a relatively coarse sampling period in the azimuth direction. In the second correlation processing, finer correlation processing operation can be performed by limiting the area to a narrow area centered on the arrival direction, so that the overall calculation time in each correlation processing is greatly reduced, and the arrival time can be increased quickly. The azimuth can be measured.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an azimuth measuring apparatus and an azimuth measuring method according to the present invention will be described below in detail with reference to FIGS. The same components as those shown in FIG. 9 are denoted by the same reference numerals, and detailed description is omitted.

FIG. 1 is a block diagram showing an embodiment of an azimuth measuring device according to the present invention, and FIG. 2 is an antenna pattern diagram of an antenna for capturing, for example, an electromagnetic wave arriving from a single direction.

That is, in FIG.
Is an antenna beam A having directivity as shown in FIG.
Is formed and is rotated or scanned 360 degrees in the azimuth direction in the direction of arrow Z1, thereby capturing an incoming electromagnetic wave (for example, an electromagnetic wave arriving from a azimuth of 45 degrees as shown in FIG. 2).

The antenna beam waveform signal obtained by the antenna 11 and including the result of capturing the electromagnetic wave is transmitted to the receiving section 12.
Supplied to The antenna beam waveform signal supplied to the receiving unit 12 is converted into an intermediate frequency signal specified for reception processing, and is supplied to the search waveform shaping unit 13. The intermediate frequency signal supplied to the direction-finding waveform shaping unit 13 is shaped into a direction-finding waveform showing the maximum swing in the arrival direction (direction of -45 degrees) of the electromagnetic wave, and the shaped direction-finding waveform signal is A / D
It is supplied to the conversion unit 14. The A / D converter 14 A / D converts the search waveform signal at a relatively coarse sampling cycle in the azimuth direction over 360 degrees in the azimuth direction, and supplies the A / D converter to the first correlation processing unit 18 which forms a digital search waveform. I do.

The first correlation processing unit 18 includes an antenna 11
A first reference waveform section 16 storing a first reference waveform having substantially the same frequency as the direction search waveform showing the maximum amplitude in the antenna beam transmission initial direction is connected to the first reference waveform. The input digital search waveform is extracted and combined with a waveform change component per unit time to form a first impulse response waveform having a maximum peak value in the arrival direction of the electromagnetic wave.

That is, the principle of operation of the first correlation processing section 18 will be described with reference to FIGS. Now, assuming that the first impulse response waveform has been input to the first correlation processing unit 18, as shown in FIG. 3, the convolution (co.) Of the first reference waveform and the first impulse response waveform is performed.
nvolume), that is, when the convolution operation is performed, a digital search waveform indicating the direction of the incoming electromagnetic wave is formed.

Therefore, conversely, as shown in FIG. 4, the first correlation processing section 18 receives the digital search waveform from the A / D conversion section 14 and inputs the initial direction of the antenna beam transmission (see FIG. 4).
By giving a first reference waveform indicating the maximum amplitude at the azimuth of 0 °) and performing a deconvolution process corresponding to the inverse operation of the convolution operation, the first reference waveform indicating the maximum peak value at the arrival direction of the electromagnetic wave is obtained. An impulse response waveform can be obtained.

That is, the first correlation processing section 18 of this embodiment extracts a waveform change component per unit time from the digital search waveform of the incoming electromagnetic wave with reference to the first reference waveform. By performing the combined deconvolution processing, a first impulse response waveform sharp in the direction of the incoming electromagnetic wave is obtained.

In the first impulse response waveform, one cycle (360 degrees) in the azimuth direction of the digital search waveform
Assuming that T is the time over which the impulse is obtained and t is the time position at which the impulse is obtained, the arrival direction θ of the electromagnetic wave is expressed by the following equation.

Θ = (t / T) × 2π [rad] Here, at the time position t of the obtained impulse, the above-described peak search and the correlation processing of the apparatus shown in FIG. And the like, a relatively sharp peak waveform can be obtained in the arrival direction, unlike the gentle waveform obtained by the above method.

As described above, even in the case of an incoming electromagnetic wave having a low frequency, the first impulse response waveform having a relatively sharp peak waveform is supplied to the data interpolation unit 19 shown in FIG.

The data interpolating section 19 is adapted for adaptive DCT (ada)
ptive Discrete Transform)
By interpolating between sampling periods in the A / D converter 14 by changing the encoding parameters as needed in accordance with the movement of the input data, a fine-grained first impulse response waveform is formed. It is supplied to the filter unit 20.

The first impulse response waveform supplied to the filter unit 20 is formed into a smooth first impulse response waveform by filtering, and the second correlation processing unit 21
Supplied to

The second correlation processing section 21 measures the approximate arrival direction θ of the electromagnetic wave from the first impulse response waveform which is smoothly shaped by filtering, and determines a predetermined direction around the arrival direction θ of the electromagnetic wave. Correlation processing similar to that performed by the first correlation processing unit 18 is performed within the azimuth angle range, and a second impulse response waveform having a maximum peak value in the arrival direction of the electromagnetic wave is formed.

That is, the second correlation processing unit 21
The maximum amplitude in the beam transmission initial azimuth of the antenna determined in advance, and the second amplitude having substantially the same frequency as the first impulse response waveform.
A second reference waveform generator 22 for generating a reference waveform is connected to the first impulse response waveform with respect to the first impulse response waveform per unit time within a selected predetermined azimuth angle range based on the second reference waveform. Are extracted and combined, and deconvolution processing is performed to obtain a second impulse response waveform sharp in the direction of the incoming electromagnetic wave.

That is, as shown in FIGS. 5 and 6, the second correlation processing section 21 calculates the approximate azimuth (θ) of the direction search waveform signal obtained by the direction search waveform shaping section 13. Since a relatively narrow range (φ) is set in the azimuth direction with respect to the center and the correlation processing is performed with the second reference waveform, the second impulse that is finer and exhibits high resolution despite a small number of deconvolution processing calculations A response waveform can be obtained, and the signal processing unit 17 can measure the direction of the incoming electromagnetic wave with high accuracy by suppressing noise even for an incoming electromagnetic wave having a relatively low frequency.

In the above embodiment, each of the correlation processing sections (18, 21) normalizes the maximum peak value of the impulse response waveform to 1, and converts this impulse response waveform to n.
(N is an integer) to obtain a better impulse response waveform.

As described above, according to the apparatus and the method of the present invention, the first and second correlation processing units use the first reference indicating the maximum amplitude in the initial beam transmission azimuth of the antenna determined in advance. An impulse showing a maximum peak value in the arrival direction of an electromagnetic wave by performing a correlation process in which a waveform change component per unit time is extracted and combined based on a waveform and a second reference waveform corresponding to the first reference waveform. Because it is configured to calculate the arrival direction of the electromagnetic wave by shaping the response waveform, the noise impulse response waveform that shows a sharp peak in the direction of the arrival electromagnetic wave and reduces the appearance of the peak in the direction other than the arrival electromagnetic wave, thereby reducing noise. And the arrival direction of the electromagnetic wave can be accurately obtained.

Further, in addition to the first correlation processing section, a second correlation processing section is constituted, and a predetermined azimuth range (φ) centered on the azimuth of the maximum peak value of the first impulse response waveform is defined as: Further, since the correlation processing is performed using the second reference waveform as a reference, the first correlation processing unit obtains the approximate arrival direction at a relatively coarse sampling interval over 360 degrees in the azimuth direction, and the second correlation processing unit calculates the arrival direction. Since finer correlation processing calculation can be performed only in a narrow area around the azimuth, the data amount can be reduced as a whole, and the calculation time in the correlation processing unit can be greatly reduced.

That is, according to the present invention, a sharp impulse response waveform is obtained in the direction of arrival by the convolution processing in two stages, so that noise and the like can be removed quickly and efficiently without performing particularly complicated waveform processing. The direction of arrival can be measured with high accuracy, and the size of the device can be reduced.

[0039]

As described in detail above, according to the present invention,
An azimuth measuring device and an azimuth measuring method capable of more accurately and quickly measuring the arrival direction of an electromagnetic wave captured by an antenna can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an azimuth measuring device according to the present invention.

FIG. 2 is an antenna pattern diagram of an antenna for capturing an electromagnetic wave arriving from a single direction in the device shown in FIG.

FIG. 3 is an explanatory diagram of a convolution process for explaining a processing operation of a first correlation processing unit in the apparatus shown in FIG. 1;

FIG. 4 is an explanatory diagram of a deconvolution process illustrating a processing operation of a first correlation processing unit in the apparatus shown in FIG. 1;

FIG. 5 is a diagram showing a calculation processing range in a second correlation processing unit for an incoming electromagnetic wave having a low frequency in the apparatus shown in FIG. 1;

FIG. 6 is a diagram showing a calculation processing range in a second correlation processing unit for an incoming electromagnetic wave having a high frequency in the apparatus shown in FIG. 1;

FIG. 7 is a waveform chart of a direction search signal of a low-frequency electromagnetic wave in a conventional direction measurement.

FIG. 8 is a waveform diagram of a direction search signal of a high-frequency electromagnetic wave in a conventional direction measurement.

FIG. 9 is a configuration diagram showing a conventional direction measurement device.

FIG. 10 is a processing waveform diagram in a correlation processing section for an incoming electromagnetic wave having a low frequency in the device shown in FIG. 7;

11 is a processing waveform diagram in a correlation processing unit for an incoming electromagnetic wave having a high frequency in the device shown in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Antenna 12 Receiving part 13 Way search waveform shaping part 14 A / D conversion part 15 Correlation processing part 16 Reference waveform generation part 17 Signal processing part 18 First correlation processing part 19 Data interpolation part 20 Filter part 21 Second correlation processing Unit 22 Second Reference Waveform Generation Unit

Claims (6)

[Claims] 1. An antenna for capturing an incoming electromagnetic wave by rotating or scanning a beam having directivity, and converting a beam waveform including a capture result obtained from the antenna into an intermediate frequency signal specified for reception processing. A receiving section, a direction search waveform shaping section for shaping a direction search signal waveform exhibiting the maximum amplitude in the arrival direction of the electromagnetic wave based on the converted output of the reception section, and a direction search signal waveform shaped by the direction search waveform shaping section An A / D converter for performing A / D conversion at a first sampling period to generate a digital search waveform; and a digital search waveform generated by the A / D conversion unit, A first reference waveform generator for generating a first reference waveform having substantially the same frequency as the digital search waveform by indicating the maximum amplitude in the initial beam transmission direction of the antenna; Previous Based on the first reference waveform, combined extracts waveform change component per unit of the digital side probe waveform time, the correlation process,
A first correlation processing unit that generates a first impulse response waveform indicating a maximum peak value in the arrival direction of the electromagnetic wave; and a maximum peak value of the first impulse response waveform generated by the first correlation processing unit. For a predetermined azimuth range centered on the azimuth, a waveform change component per unit time of the digital search waveform is extracted and combined based on a second reference waveform corresponding to the first reference waveform, and the correlation is calculated. Processing, a second peak value indicating the maximum peak value in the arrival direction of the electromagnetic wave is obtained.
A second correlation processing unit that generates the impulse response waveform of the second correlation processing unit; and a signal waveform processing unit that calculates the arrival direction of the electromagnetic wave based on the second impulse response waveform formed by the second correlation processing unit. An azimuth measuring device characterized by the above-mentioned. 2. The apparatus according to claim 1, wherein said first impulse response waveform is shaped after a data interpolation in an azimuth direction and then supplied to said second correlation processing unit. The azimuth measuring device according to 1. 3. The first correlation processing section executes a deconvolution process corresponding to an inverse operation of a convolution operation on the digital search waveform and the first reference waveform, thereby executing the first correlation processing. The second correlation processing unit obtains an impulse response waveform, and performs a deconvolution process corresponding to an inverse operation of a convolution operation on the first impulse response waveform and the second reference waveform, thereby obtaining the impulse response waveform. 3. The azimuth measuring apparatus according to claim 1, wherein the second impulse response waveform is obtained. 4. After rotating or scanning a directional beam to convert a beam waveform including a capture result obtained from an antenna for capturing an incoming electromagnetic wave into an intermediate frequency signal specified for reception processing, A direction search waveform showing the maximum amplitude in the arrival direction of the electromagnetic wave is formed, and this direction search waveform is A / D-converted at a first sampling period to form a digital direction search waveform. Correlation processing is performed by extracting and combining a waveform change component per unit time of the digital search waveform with reference to a first reference waveform having a maximum amplitude in the initial azimuth and having substantially the same frequency as the digital search waveform. Thus, a first impulse response waveform indicating the maximum peak value in the arrival direction of the electromagnetic wave is formed, and the direction of the maximum peak value of the generated first impulse response waveform is formed. With respect to a predetermined azimuth range centered on the basis of a second reference waveform corresponding to the first reference waveform, a waveform change component per unit time of the digital search waveform is extracted and combined, and a correlation process is performed. An azimuth measuring method, comprising: generating a second impulse response waveform indicating a maximum peak value in the arrival direction of the electromagnetic wave, and measuring the arrival direction of the electromagnetic wave based on the second impulse response waveform. 5. The apparatus according to claim 4, wherein the first impulse response waveform is supplied to the second correlation processing section after being subjected to azimuth direction data interpolation and waveform shaping. The orientation measurement method described. 6. The first impulse response waveform is obtained by a deconvolution process corresponding to an inverse operation of a convolution operation on the digital search waveform and the first reference waveform, and the second impulse response waveform is obtained. 6. The waveform according to claim 4, wherein the waveform is obtained by deconvolution processing corresponding to an inverse operation of a convolution operation on the first impulse response waveform and the second reference waveform.
The azimuth measurement method described in 1.