JP3556534B2 - Direction measuring device and direction measuring method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an azimuth measuring device and an azimuth measuring method for capturing an arriving electromagnetic wave by using an antenna that rotates or scans a beam having directivity and measuring the azimuth of arrival of the electromagnetic wave.
[0002]
[Prior art]
In general, an azimuth measuring device that captures an electromagnetic wave arriving by an antenna that rotates a directional beam and measures the azimuth of arrival is a direction finding signal of the electromagnetic wave captured by rotating the rotating beam of the antenna 360 degrees in the azimuth direction. The waveforms are as shown in FIGS. 7 and 8, respectively. The low-frequency reception electromagnetic wave has a gentle waveform in the direction of arrival as shown in FIG. 7, and the high-frequency reception electromagnetic wave has a sharp waveform as shown in FIG. It has a sharp waveform.
[0003]
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 was most strongly received, that is, the waveform. Is the azimuth indicating the maximum peak value.
[0004]
In the method of automatically reading the arrival direction of the electromagnetic wave from the direction search signal waveform of the electromagnetic wave shown in FIGS. 7 and 8, a peak search process of the waveform is performed, and a maximum peak value is obtained from the search result to obtain the arrival direction. There is a way to determine
[0005]
However, as shown in FIG. 8, when the direction signal waveform receives a high-frequency electromagnetic wave, the waveform at the maximum peak becomes sharp, so that it is relatively easy to obtain the direction of arrival. As the frequency becomes lower, as shown in FIG. 7, the maximum peak portion becomes a gentle waveform, so that it is difficult to determine the azimuth at a low reception frequency, or even if it is determined, a large error tends to occur.
[0006]
In addition, even when the reception frequency is high, noise is often superimposed on the direction search signal waveform, and the waveform is disturbed, so that accurate azimuth determination has not been easy.
[0007]
Therefore, in another method of automatically reading the direction of arrival by relatively suppressing noise more, after sampling the direction finding signal waveform in the direction of azimuth, performing correlation processing with a reference pattern prepared in advance, A method of finding the direction at which the maximum peak value was obtained has been considered.
[0008]
That is, the apparatus for measuring the azimuth by the correlation process is configured as shown in FIG. 9, and the receiving unit 12 converts the rotating beam obtained from the antenna 11 into a beam waveform including the result of capturing the electromagnetic wave by the receiving unit 12. After the conversion into the 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. 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.
[0009]
Accordingly, even in the correlation process by the correlation processing unit 15 in FIG. 9, in the direction of arrival, a gentle search signal waveform is obtained as shown in FIG. 10 when the reception frequency is low, and FIG. Although a sharp search signal waveform is obtained as shown in FIG. 11, unlike the peak search processing, a single azimuth waveform with a relatively suppressed noise component is obtained. However, in order to increase the resolution and measure the direction of arrival with high accuracy, it is required to make the sampling interval in the A / D converter 14 smaller in the azimuth direction. Expansion was inevitable.
[0010]
[Problems to be solved by the invention]
As described above, in the azimuth measurement method considered conventionally, when the frequency of the arriving electromagnetic wave is low, the waveform of the direction signal becomes gentle, making it difficult to determine the azimuth of arrival with high accuracy. There is a problem that the measurement result of the direction of arrival tends to include a large error.
[0011]
Also, even when measuring the direction of an incoming electromagnetic wave by correlation processing, it is necessary to make the sampling interval finer in order to obtain a more accurate direction measurement result. There has been a problem that processing takes a lot of time.
[0012]
Therefore, an object of the present invention is to provide an azimuth measuring apparatus and an azimuth measuring method capable of measuring the arrival direction 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 relates to: 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 to provide 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 forming unit that shapes a direction finding signal waveform that indicates the maximum amplitude in the arrival direction of the electromagnetic wave based on the converted output of the receiving unit. An A / D conversion unit 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 conversion unit that generates the digital direction search waveform. 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 preset beam transmission initial direction of the antenna with respect to the digital search waveform A waveform change component per unit time of the digital search waveform based on the first reference waveform from the first reference waveform generator, and a combination thereof. A first correlation processing unit that generates a first impulse response waveform indicating a maximum peak value in an arrival direction; and a direction of 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 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. 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, and a second impulse response waveform formed by the second correlation processing unit based on the second impulse response waveform. Characterized by comprising a signal waveform processing section for calculating the arrival direction of the electromagnetic wave.
[0014]
As described above, in the first invention apparatus, the first and second correlation processing units convert the first reference waveform indicating the maximum amplitude in the preset beam transmission initial azimuth of the antenna and the first reference waveform into the first reference waveform. The impulse response waveform showing the maximum peak value in the arrival direction of the electromagnetic wave is formed by correlation processing in which the waveform change components per unit time are extracted and combined with each other with reference to the corresponding second reference waveform, and the arrival direction of the electromagnetic wave is obtained. Is calculated, an impulse response waveform having a sharp peak in the arrival direction 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.
[0015]
Further, in the device of the present invention, a second correlation processing unit is configured in addition to the first correlation processing unit, and a second azimuth range is set to a predetermined azimuth range centered on the azimuth of the maximum peak value of the first impulse response waveform. Since the correlation processing is performed with reference to the second reference waveform, 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. Since a finer correlation processing operation can be performed only in a narrow area at the center, the amount of calculation data of each correlation processing unit as a whole can be significantly reduced, and the direction of arrival can be quickly obtained.
[0016]
According to a second aspect of the present invention, in the azimuth measuring method, an intermediate frequency signal specified for reception processing by rotating or scanning a beam having directivity and obtaining a beam waveform including a capture result obtained from an antenna for capturing an incoming electromagnetic wave. After that, 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, which is obtained in advance. The maximum amplitude in the beam transmission initial direction of the antenna, and extracting a waveform change component per unit time of the digital search waveform with reference to a first reference waveform having substantially the same frequency as the digital search waveform. By performing correlation processing in combination, a first impulse response waveform showing a maximum peak value in the arrival direction of the electromagnetic wave is formed, and the generated first impulse response wave is generated. Extracting a waveform change component per unit time of the digital search waveform from a predetermined azimuth range centered on the azimuth of the maximum peak value with reference to a second reference waveform corresponding to the first reference waveform. Generating a second impulse response waveform having a maximum peak value in the arrival direction of the electromagnetic wave by correlation processing, and then measuring the arrival direction of the electromagnetic wave based on the second impulse response waveform. I do.
[0017]
As described above, also in the second invention, the first and second correlation processing sections extract and combine the waveform change components per unit time, respectively, based on the first reference waveform and the second reference waveform. The impulse response waveform that shows the maximum peak value in the arrival direction of the electromagnetic wave is calculated and the arrival direction of the electromagnetic wave is calculated, so the appearance of waveform peaks other than the arrival direction is reduced, and the electromagnetic wave Can be measured.
[0018]
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, and obtains the second direction. In the correlation processing, finer-grained correlation processing calculations can be performed only in a narrow area centered on the direction of arrival, so the overall calculation time in each correlation processing is greatly reduced, and the direction of arrival can be measured quickly. can do.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an azimuth measuring apparatus and an azimuth measuring method according to the present invention will be described in detail with reference to FIGS. Note that the same components as those shown in FIG. 9 are denoted by the same reference numerals, and detailed description is omitted.
[0020]
FIG. 1 is a configuration 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.
[0021]
That is, in FIG. 1, the antenna 11 forms an antenna beam A having directivity as shown in FIG. 2, and rotates or scans in the azimuthal direction 360 degrees in the direction of arrow Z1, thereby arriving electromagnetic waves (in FIG. 2). As shown by, for example, an electromagnetic wave arriving from the azimuth direction of 45 degrees is captured.
[0022]
An antenna beam waveform signal obtained by the antenna 11 and including the result of capturing the electromagnetic wave is supplied to the receiving unit 12. The antenna beam waveform signal supplied to the reception 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 of the electromagnetic wave (direction of -45 degrees), and the shaped direction-finding waveform signal is The signal is supplied to the A / D converter 14. The A / D converter 14 A / D converts the search waveform signal at a relatively coarse sampling period in the azimuth direction over 360 degrees in the azimuth direction, and supplies the signal to a first correlation processing unit 18 that forms a digital search waveform. I do.
[0023]
The first correlation processing unit 18 is connected to a first reference waveform unit 16 that stores a first reference waveform having substantially the same frequency as the quadrature waveform having the maximum amplitude in the antenna beam transmission initial direction of the antenna 11. Then, based on the first reference waveform, the input digital search waveform is combined with a waveform change component per unit time extracted and combined, and a first impulse indicating a maximum peak value in the arrival direction of the electromagnetic wave. Shape the response waveform.
[0024]
That is, the operation principle of the first correlation processing unit 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 of the first reference waveform and the first impulse response waveform is performed. That is, when the convolution operation is performed, a digital search waveform indicating the direction of the incoming electromagnetic wave is formed.
[0025]
Therefore, conversely, as shown in FIG. 4, the first correlation processing unit 18 receives the digital search waveform from the A / D conversion unit 14 and inputs the initial direction of the antenna beam transmission (in FIG. The first impulse response waveform that indicates the maximum peak value in the arrival direction of the electromagnetic wave is obtained by giving a first reference waveform indicating the maximum amplitude in the direction of the electromagnetic wave and performing a deconvolution process corresponding to the inverse operation of the convolution operation. be able to.
[0026]
That is, the first correlation processing unit 18 of this embodiment extracts the waveform change component per unit time from the digital search waveform of the incoming electromagnetic wave with reference to the first reference waveform and combines the deconvolution with the digital reference waveform. By performing the processing, a first impulse response waveform sharp in the direction of the incoming electromagnetic wave is obtained.
[0027]
In this first impulse response waveform, assuming that the time over one cycle (360 degrees) in the azimuthal direction of the digital search waveform is T and the time position at which the impulse is obtained is t, the arrival azimuth θ of the electromagnetic wave is given by the following equation. Is represented.
[0028]
θ = (t / T) × 2π [rad]
Here, at the time position t of the obtained impulse, even the low-frequency arriving electromagnetic wave differs from the gentle waveform obtained by the above-described peak search and the correlation processing of the device shown in FIG. A relatively sharp peak waveform can be obtained.
[0029]
As described above, the first impulse response waveform having a relatively sharp peak waveform is supplied to the data interpolation unit 19 shown in FIG.
[0030]
The data interpolation unit 19 is composed of an adaptive DCT (Adaptive Discrete Transform), and interpolates between sampling periods in the A / D conversion unit 14 by changing encoding parameters as needed according to the movement of input data. A first impulse response waveform having a fine waveform is formed and supplied to the filter section 20.
[0031]
The first impulse response waveform supplied to the filter unit 20 is shaped into a smooth first impulse response waveform by filtering and supplied to the second correlation processing unit 21.
[0032]
The second correlation processing unit 21 measures the approximate azimuth θ of the electromagnetic wave from the first impulse response waveform smoothly shaped by filtering, and sets a predetermined azimuth angle range around the arrival azimuth θ of the electromagnetic wave. The same correlation processing as that performed by the first correlation processing unit 18 is performed within the section to form a second impulse response waveform having a maximum peak value in the arrival direction of the electromagnetic wave.
[0033]
That is, the second correlation processing unit 21 is configured in the same manner as the first correlation processing unit 18, shows the maximum amplitude in the beam transmission initial azimuth of the antenna determined in advance, and is substantially the same as the first impulse response waveform. A second reference waveform generator 22 for generating a second reference waveform having the same frequency is connected, and a predetermined azimuth angle selected with respect to the first impulse response waveform with respect to the second reference waveform. A waveform change component per unit time within the range is extracted and combined, and a deconvolution process is performed to obtain a second impulse response waveform sharp in the direction of an incoming electromagnetic wave.
[0034]
That is, as shown in FIGS. 5 and 6, the second correlation processing unit 21 applies a center to the approximate azimuth (θ) of the direction search waveform signal obtained by the direction search waveform shaping unit 13. Since a relatively narrow range (φ) is set in the azimuth direction and the correlation processing is performed with the second reference waveform, the second impulse response waveform exhibiting finer and higher resolution can be obtained despite a small number of deconvolution processing calculations. Accordingly, the signal processing unit 17 can measure the direction of the incoming electromagnetic wave with high accuracy by suppressing noise even for the incoming electromagnetic wave having a relatively low frequency.
[0035]
In the above embodiment, in each of the correlation processing units (18, 21), the maximum peak value of the impulse response waveform is normalized to 1, and this impulse response waveform is raised to the power of n (n is an integer) for better performance. An impulse response waveform may be obtained.
[0036]
As described above, according to the apparatus and the method of the present invention, the first and second correlation processing units determine the first reference waveform indicating the maximum amplitude in the beam transmission initial azimuth of the antenna determined in advance, and Based on a second reference waveform corresponding to the first reference waveform, a correlation process is performed by extracting and combining waveform change components per unit time to obtain an impulse response waveform indicating the maximum peak value in the arrival direction of the electromagnetic wave. Since it is configured to calculate the arrival direction of the electromagnetic wave by shaping, it suppresses noise by forming an impulse response waveform that shows a sharp peak in the direction of the arrival electromagnetic wave and reduces the appearance of peaks in directions other than the arrival electromagnetic wave. , The arrival direction of the electromagnetic wave can be accurately obtained.
[0037]
Further, in addition to the first correlation processing unit, a second correlation processing unit is formed, and a second azimuth range (φ) centered on the azimuth of the maximum peak value of the first impulse response waveform is further added to the second azimuth range. Since the correlation processing is performed using the 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 approximate arrival direction as the center. Since the finer correlation processing operation can be performed only in the narrow area described above, the data amount can be reduced as a whole, and the calculation time in the correlation processing unit can be greatly reduced.
[0038]
That is, according to the present invention, since a sharp impulse response waveform is obtained in the arrival direction by the convolution processing in two stages, noise and the like can be removed quickly and with high precision without performing any particularly complicated waveform processing. The azimuth can be measured, and the device can be downsized.
[0039]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide 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.
[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 that captures electromagnetic waves 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 device shown in FIG. 1;
FIG. 4 is an explanatory diagram of a deconvolution process for explaining 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 finding 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 unit for an incoming electromagnetic wave having a low frequency in the apparatus shown in FIG. 7;
11 is a processing waveform diagram in a correlation processing section 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)

An antenna that rotates or scans a directional beam to capture an incoming electromagnetic wave,
A receiving unit that converts a beam waveform including a capture result obtained from the antenna into an intermediate frequency signal specified for reception processing,
A direction search waveform shaping unit that shapes a direction search signal waveform indicating the maximum amplitude in the arrival direction of the electromagnetic wave based on the converted output of the reception unit,
An A / D conversion unit 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;
A first reference having a maximum amplitude in a preset beam azimuth of the antenna and having substantially the same frequency as that of the digital search waveform with respect to the digital search waveform generated by the A / D converter. A first reference waveform generator for generating a waveform;
With reference to the first reference waveform from the first reference waveform generation unit, a waveform change component per unit time of the digital search waveform is extracted and combined, and a maximum value is obtained in the arrival direction of the electromagnetic wave by correlation processing. A first correlation processing unit that generates a first impulse response waveform indicating a peak value;
A second reference waveform corresponding to the first reference waveform is defined as a reference in a predetermined azimuth range centered on the azimuth of the maximum peak value of the first impulse response waveform generated by the first correlation processing unit. A second correlation process of extracting and combining a waveform change component per unit time of the digital direction finding waveform, and generating a second impulse response waveform having a maximum peak value in an arrival direction of the electromagnetic wave by a correlation process. Department and
An azimuth measuring device, comprising: a signal waveform processing unit that calculates an arrival azimuth of the electromagnetic wave based on the second impulse response waveform formed by the second correlation processing unit. 2. The azimuth measurement device according to claim 1, wherein the first impulse response waveform is configured to be subjected to azimuth direction data interpolation, shaped, and then supplied to the second correlation processing unit. 3. apparatus. The first correlation processing unit obtains the first impulse response waveform by performing a deconvolution process corresponding to an inverse operation of a convolution operation on the digital search waveform and the first reference waveform. ,
The second correlation processing section 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 second impulse response waveform. 3. The azimuth measuring device according to claim 1, wherein the azimuth is determined. After rotating or scanning a beam having directivity, after converting a beam waveform including a capture result obtained from an antenna that captures an incoming electromagnetic wave into an intermediate frequency signal specified for reception processing, in the arrival direction of the electromagnetic wave After forming a direction search waveform showing the maximum amplitude, performing A / D conversion on the direction search waveform at the first sampling period to form a digital direction search waveform, the maximum amplitude is obtained at the beam transmission initial direction of the antenna determined in advance. By extracting and combining a waveform change component per unit time of the digital search waveform with reference to a first reference waveform having substantially the same frequency as the digital search waveform, and performing a correlation process, the electromagnetic wave Shaping the first impulse response waveform showing the maximum peak value at the arrival direction of
For a predetermined azimuth range centered on the azimuth of the maximum peak value of the generated first impulse response waveform, the digital search waveform is defined based on a second reference waveform corresponding to the first reference waveform. After extracting and combining the waveform change components per unit time and performing a correlation process to generate a second impulse response waveform indicating the maximum peak value in the arrival direction of the electromagnetic wave, the electromagnetic wave is generated based on the second impulse response waveform. An azimuth measuring method characterized by measuring an arrival azimuth of a vehicle. The azimuth measuring method according to claim 4, wherein the first impulse response waveform is configured to be supplied to the second correlation processing unit after data interpolation and waveform shaping in the azimuth direction. . 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,
5. The method according to claim 4, wherein the second impulse response waveform is obtained by a deconvolution process corresponding to an inverse operation of a convolution operation on the first impulse response waveform and the second reference waveform. Item 6. The azimuth measuring method according to Item 5.

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