JP2009020015A - Radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar system observing the object distance and direction without enlarging processing or circuit scale. <P>SOLUTION: The apparatus comprises: a one dimension DBF (Digital Beam Forming) array antenna 1 comprising a plurality of sub-arrays that are placed in one direction to form a circular aperture, and that have different phase centers and are divided into the circular aperture in a direction perpendicular to the one direction; an ICA processing part 2 performing complex ICA (Independent Component Analysis) against sub-array signal before combining mono-pulse that is fed from the plurality of sub-arrays of the one dimension DBF array antenna to separate the object signal and the unnecessary wave signal; and a distance measuring part 5 measuring the distance, based on the object signal separated by the ICA processing part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radar apparatus that measures a target distance and a target direction under an unnecessary wave environment input from a main lobe and a side lobe, and more particularly to a technique for suppressing unnecessary waves.

  FIG. 19 is a diagram for explaining a signal state in an unnecessary wave environment. In the radio wave environment, as shown in FIG. 19A, in addition to the target, unnecessary waves such as pulse jamming waves and continuous jamming waves such as clutter are mixed. In such an unnecessary wave environment, the received signals received by the antenna of the radar device are mixed signal 1 to mixed signal 3 in which the target and unnecessary waves are mixed, as shown in FIG. Therefore, since only the target signal cannot be separated, distance measurement and angle measurement with respect to the target cannot be performed.

  SLC (Sidelobe Canceller) etc. when there is sidelobe interference in order to detect the target signal and detect the distance and direction under unnecessary wave environment where unnecessary waves such as broadband interference and clutter exist In the case where there is a clutter, a filter process on the frequency axis is required like a Doppler filter process. In particular, when a large number of filter coefficients (such as tapped delay lines) are changed by adaptation, there is a problem that the processing scale or circuit scale for suppressing unwanted waves increases.

In addition, in the case of a broadband mainlobe jammer, there is a problem that the target cannot be detected because the filter on the spatial axis and the frequency axis cannot be separated, and the target distance and direction cannot be observed.
Nemoto Translation, Detailed Independent Component Analysis, Tokyo Denki University Press, pp.164-217, 2005 ELLA BINGHAM, AAPO HYVARINEN, "A FAST FIXED-POINT ALGOTITHM FOR INDEPENDENTCOMPONENT ANALYSIS OF COMPLEX VALUED SIGNALS", International Journal of Neural Systems, Vol.10, No.1 (Feb.2000)

  As described above, the conventional radar apparatus requires a filtering process on the spatial axis and a filtering process on the frequency axis, and particularly when many filter coefficients are changed by adaptation, the processing scale or circuit scale becomes large. There is a problem. Furthermore, in the case of a broadband mainlobe jammer, there is a problem that the target cannot be detected because the filter on the spatial axis and the frequency axis cannot be separated, and the target distance and direction cannot be observed.

  The present invention has been made to solve the above-mentioned problems, and the problem is to observe the target distance and direction without increasing the processing scale or circuit scale as much as possible even in an unnecessary wave environment. An object of the present invention is to provide a radar device that can be used.

  In order to solve the above-mentioned problems, a first invention includes a plurality of subarrays having different phase centers that are arranged in one direction so as to form a circular opening and are divided in a direction perpendicular to the one direction. By performing complex ICA (Independent Component Analysis) on a subarray signal before monopulse synthesis sent from a plurality of subarrays of a one-dimensional DBF (Digital Beam Forming) array antenna and a one-dimensional DBF array antenna, An ICA processing unit that separates the target signal and the unwanted wave signal and a distance measuring unit that measures the distance based on the target signal separated by the ICA processing unit are provided.

  Further, the second invention is a one-dimensional DBF (Digital Beam Forming) including a plurality of subarrays having different phase centers, which are arranged in one direction so as to form a circular opening and are divided in a direction orthogonal to the one direction. ) An array antenna, a subarray division processing unit that converts a monopulse synthesized signal sent from a plurality of subarrays of the one-dimensional DBF array antenna into a subarray signal before monopulse synthesis, and a subarray sent from the subarray division processing unit By performing complex ICA (Independent Component Analysis) on the signal, the ICA processing unit that separates the target signal and the unwanted wave signal, and the distance is measured based on the target signal separated by the ICA processing unit. And a distance measuring unit.

  The third invention is an antenna that outputs a monopulse beam composed of a sum signal Σ, an AZ plane difference signal ΔAZ, and an EL plane difference signal ΔEL, and a subarray division processing unit that converts the monopulse beam output from the antenna into a subarray signal And an ICA processing unit that separates the target signal and the unwanted wave signal by performing complex ICA (Independent Component Analysis) on the subarray signal sent from the subarray division processing unit. And a distance measuring unit for measuring a distance based on the target signal separated by the above.

  Further, a fourth aspect of the present invention is the angle measuring unit for detecting an azimuth by null steering using subarray signals from a plurality of subarrays having different subcenter phase center intervals in any one of the first to third aspects. It is provided with.

  In addition, in a fifth aspect based on any one of the first to third aspects, the ICA processing unit separates the target signal and the unnecessary wave signal by performing a real number ICA on the input subarray signal. It is characterized by doing.

  In a sixth aspect based on the fourth aspect, the ICA processing unit separates the target signal and the unwanted wave signal by performing real number ICA on the input subarray signal, and the angle measuring unit includes: A complex signal is generated from the separated real target signal, and an azimuth is detected by null steering based on the generated complex signal.

  According to the present invention, even in an unnecessary wave environment, only a target signal can be extracted and a target distance and direction can be observed with a simple processing scale or circuit scale without using a large number of filter coefficients. Further, even when there are a plurality of target signals, since the distance and direction of each target can be known, even when a target is input from the side lobe direction with a high sidelobe antenna, only the target input from the main lobe can be separated.

  Specifically, according to the first aspect of the present invention, the target signal and the unwanted wave signal are obtained by performing complex ICA on the sub-array signals before monopulse synthesis sent from the plurality of sub-arrays of the one-dimensional DBF array antenna. The target signal is extracted and only the target signal is extracted and the distance to the target is observed, so even in an unnecessary wave environment, the distance to the target can be reduced without increasing the processing scale or circuit scale as much as possible. Can be observed.

  According to the second aspect of the present invention, the monopulse synthesized signal sent from the plurality of subarrays of the one-dimensional DBF array antenna is converted into the subarray signal before monopulse synthesis, and the subarray signal after the conversion is converted. By performing complex ICA, the mixed signal of the target signal and unnecessary wave is separated, and only the target signal is extracted and the distance to the target is observed. Therefore, even in an unnecessary wave environment, the processing scale or circuit scale It is possible to observe the distance to the target without enlarging as much as possible.

  According to the third aspect of the present invention, the monopulse beam composed of the sum signal Σ, the AZ plane difference signal ΔAZ, and the EL plane difference signal ΔEL is converted into a subarray signal, and complex ICA is performed on the converted subarray signal. Therefore, the target signal and unwanted wave mixed signal are separated, only the target signal is extracted, and the distance to the target is observed, so even in an unnecessary wave environment, the processing scale or circuit scale can be made as large as possible. Without observing the distance to the target.

  According to the fourth aspect of the present invention, since the azimuth is detected by null steering using the subarray signals from a plurality of subarrays having different subcenter phase center intervals, processing can be performed even in an unnecessary wave environment. The distance to the target and the direction of the target can be observed without increasing the scale or the circuit scale as much as possible.

  According to the fifth aspect of the present invention, the target signal and the unnecessary wave signal are separated by performing real number ICA on the input subarray signal, and only the target signal is extracted, and the distance to the target is obtained. Therefore, the operation scale can be reduced as compared with the case of performing complex ICA.

  According to the sixth aspect of the present invention, the target signal and the unwanted wave signal are separated by performing real number ICA on the input subarray signal, and only the target signal is extracted, and the distance to the target is obtained. Since the target orientation is observed, the scale of computation can be reduced as compared with the case of performing complex ICA.

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

  FIG. 1 is a block diagram illustrating a configuration of a radar apparatus according to Embodiment 1 of the present invention. The radar apparatus includes an antenna 1, an ICA (Independent Component Analysis) processing unit 2, a signal extraction unit 3, a signal identification unit 4, and a ranging unit 5.

  The antenna 1 includes a one-dimensional DBF (Digital Beam Forming) array antenna, and includes a circular aperture antenna 10 and a small antenna 11 as shown in FIG. In this circular aperture antenna 10, the EL direction is a one-dimensional DBF, and analog synthesis is performed in the AZ direction. The AZ direction is originally divided into two apertures in order to create a monopulse beam, and the EL direction is divided and synthesized in units of N (N is a positive integer). The output of the subarray (the signal before monopulse synthesis) is obtained. This “N” is determined such that the number of subarrays is equal to or greater than the number of independent components described later.

  Since each subarray is arranged so that a circular opening is formed, the phase center of each subarray is different. Therefore, this circular aperture antenna 10 has N × 2 degrees of freedom. The outputs of the N × 2 divided subarrays constituting the circular aperture antenna 10 are sent to the ICA processing unit 2 as subarray signals L1 to LN and R1 to RN.

  The small antenna 11 is optional and is additionally arranged as a part of the circular opening when the degree of freedom is insufficient. The position and number of the small antennas 11 are arbitrary. Signals S <b> 1 to SP (P is a positive integer) output from the small antenna 11 are sent to the ICA processing unit 2.

  Based on the signal from the antenna 1, the ICA processing unit 2 separates the target signal from the signal in which the target and the unnecessary wave are mixed by ICA. The details of ICA are described in Non-Patent Document 1, but here, the principle of ICA will be briefly described.

Assuming that the independent variable is S, the observed variable X can be expressed by the following equation using the mixing matrix A.

Here, when the observation variables are generalized and expressed in the space-time (time-space) axis,

A: Mixing matrix x; Observation variable N: Number of subarrays (AZ axis / EL axis)
M; PRI number s; Independent variable NM; Number of observation variable P; Number of independent variable k; Number of samples (number of range cells)
T: transposition. In the case of only the space axis, M = 1, and in the case of only the time axis, N = 1 may be set. FIG. 3 shows observation variables input as input signals to the ICA processing unit 2. The observation variable is a two-dimensional signal of AZ and EL in a space formed by a two-dimensional subarray, and further becomes a signal for each range cell for each PRI unit on the time axis. FIG. 4 is a diagram illustrating an actual configuration of the antenna 1 for acquiring observation variables.

ICA is a method of estimating the mixing matrix A from the observation matrix X using only the assumption that the independent components are statistically independent without using information about the independent components and the mixing matrix. That is, if the restored data is Y,

The restoration matrix W is calculated so that the Y components such that In this case, since the information regarding the independent component and the mixing matrix is not used, ambiguity remains in the size and order of the components of the restored data.

Prior to this ICA, decorrelation is performed as preprocessing. This facilitates calculation of the restoration matrix.

here,
Q: transformation matrix for decorrelation I; unit matrix E {}; average An algorithm for calculating a restoration matrix using this decorrelated X is, for example, as follows in complex number FAST ICA (details) (See Non-Patent Document 2).

here,
H: conjugate transpose *; complex conjugate ‖ ；; norm g; function g ′; derivative of g For example, as in the following equation (a is a constant).

As described above, the restoration matrix W per independent component can be calculated. In order to extend this to a plurality of components, the following equation is calculated by a method based on the Gram Schmidt orthogonalization method.

here,
p: p-th independent component (p = 1 to P)
The ICA algorithm described above is an example, and other methods such as a method using kurtosis (fourth-order cumulant) (see Non-Patent Document 1) or the like can be used as an independent evaluation amount.

  By the above-described processing in the ICA processing unit 2, the signals of the target, the clutter, and the jamming wave can be separated even in a radio wave environment in which the target, the clutter, and the jamming wave are mixed as shown in FIG.

  That is, in an unnecessary wave environment in which unnecessary waves such as a pulse interference wave and a continuous interference wave such as a clutter are mixed in addition to the target as shown in FIG. ), The mixed signal 1 to the mixed signal 3 in which the target and the unnecessary wave are mixed are obtained. However, as shown in FIG. And are sent to the signal extraction unit 3 as a target signal, a pulse jamming signal, and a continuous jamming signal, respectively.

  The signal extraction unit 3 extracts a signal exceeding a predetermined threshold for each independent component as shown in FIG. The signal extracted by the signal extraction unit 3 is sent to the signal identification unit 4.

  The signal identification unit 4 identifies the signal transmitted from the signal extraction unit 3. That is, as shown in FIG. 7A, the signal identification unit 4 identifies that the signal transmitted from the signal extraction unit 3 is a pulse interference signal when the signal periodically exceeds the threshold. As shown in (b), when several of the signals sent from the signal extraction unit 3 exceed the threshold with a predetermined width, the signal is identified as a target signal, as shown in FIG. When the signal sent from the signal extraction unit 3 continuously exceeds the threshold, it is identified that it is a continuous disturbance signal or a clutter signal. The identification result in the signal identification unit 4 is sent to the distance measuring unit 5.

  The distance measuring unit 5 measures the distance to the target when the identification result sent from the signal identifying unit 4 indicates the target signal. A measurement result in the distance measuring unit 5 is output to the outside as a target distance.

  Next, the operation of the radar apparatus according to Embodiment 1 of the present invention configured as described above will be described with reference to the flowchart shown in FIG.

  First, sub-array input is performed (step S11). That is, the subarray signals L1 to LN and R1 to RN obtained from the subarray of the antenna 1 are sent to the ICA processing unit 2. Next, ICA processing is performed (step S12). That is, the ICA processing unit 2 separates the signal sent from the antenna 1 into a target signal, a pulse jamming signal, and a continuous jamming signal and sends them to the signal extraction unit 3. Next, signal extraction is performed (step S13). That is, the signal extraction unit 3 extracts a signal exceeding a predetermined threshold for each independent component, and sends the signal to the signal identification unit 4.

  Next, signal identification is performed (step S14). That is, the signal identification unit 4 identifies whether the signal transmitted from the signal extraction unit 3 is a pulse jamming signal, a target signal, a continuous jamming signal, or a clutter signal, and the discrimination result. Is sent to the distance measuring unit 5. Next, distance measurement is performed (step S15). That is, the distance measuring unit 5 measures the distance to the target and outputs the measurement result to the outside as the target distance when the identification result sent from the signal identifying unit 4 indicates the target signal. To do.

FIG. 9 is a diagram showing a configuration of the antenna 1 used in the radar apparatus according to Embodiment 2 of the present invention. The antenna 1 is configured by adding a subarray division processing unit 12 to the antenna of the radar apparatus according to the first embodiment. In the circular aperture antenna 10, the EL direction is a one-dimensional DBF, and analog synthesis is performed in the AZ direction. Regarding the AZ direction, a sum signal Σ and a difference signal Δ are obtained by a power supply circuit (not shown). From this sum signal Σ and difference signal Δ, a signal divided into two apertures is obtained by the following equation.

here,
Xl; one surface divided into two apertures Xr; other surface divided into two apertures Σ; sum signal ΔAZ; AZ surface difference signal From equation (7), the aperture divided signal can be calculated by the following calculation.

  In the circular aperture antenna 10, the EL direction is divided into N divided units and combined to obtain an output of a subarray of N × 2 divided units (monopulse combined signal). The output of the subarray of N × 2 division units constituting the circular aperture antenna 10 is sent to the subarray division processing unit 12 as subarray signals Σ1 to ΣN and Δ1 to ΔN.

  The subarray division processing unit 12 converts the subarray signals Σ1 to ΣN and Δ1 to ΔN that have been subjected to monopulse synthesis into subarray signals L1 to LN and R1 to RN before monopulse synthesis, and sends them to the ICA processing unit 2. Since the subarrays are arranged so that circular openings are formed, the phase centers of the subarrays are different from each other. Therefore, this circular aperture antenna 10 has N × 2 degrees of freedom. Furthermore, when the degree of freedom is insufficient, it can be additionally arranged on the small antenna 11 as a part of the circular opening.

  Next, the operation of the radar apparatus according to Embodiment 2 of the present invention configured as described above will be described with reference to the flowchart shown in FIG. Note that steps that perform the same processing as that of the radar apparatus according to the first embodiment illustrated in FIG. 8 are denoted by the same reference numerals as those used in FIG.

  First, monopulse input is performed (step S21). In other words, monopulse-combined subarray signals Σ 1 to ΣN and Δ 1 to ΔN obtained from the circular aperture antenna of antenna 1 are sent to subarray division processing unit 12. Next, subarray conversion is performed (step S22). That is, the subarray division processing unit 12 converts the subarray signals Σ1 to ΣN and Δ1 to ΔN that are monopulse synthesized into the subarray signals L1 to LN and R1 to RN before monopulse synthesis, and sends them to the ICA processing unit 2. The subsequent processing is the same as the processing in the radar apparatus according to the first embodiment.

  The radar apparatus according to Embodiment 3 of the present invention uses the output of a two-dimensional monopulse beam (Σ, ΔAZ, ΔEL) to obtain subarray outputs of the AZ plane and the EL plane.

FIG. 11 is a diagram illustrating the antenna 1 used in the radar apparatus according to Embodiment 3 of the present invention. In the antenna 1, the monopulse comparator 12 generates a sum signal Σ, an AZ plane difference signal ΔAZ, and an EL plane difference signal ΔEL from the aperture-divided signal. Now, as shown in FIG. 11, assuming that the signals obtained by aperture division are X11, X12, X21 and X22, the monopulse signal can be expressed by the following equation.

here,
Σ; Sum signal ΔAZ; AZ surface difference signal ΔEL; EL surface difference signal From equation (9), the aperture division signal can be calculated by the following calculation.

  FIG. 12 is a diagram illustrating a configuration of the antenna 1 for obtaining an observation variable as an aperture division signal obtained by Expression (9). The subarray division processing unit 12 executes the process shown in the equation (9).

  The configuration and operation of the radar apparatus according to the third embodiment are the same as those of the radar apparatus according to the first or second embodiment, including the addition of a small antenna 11 as necessary, except that the subarray output is used. It is.

  In the radar apparatus according to the third embodiment, the subarray output is calculated from the monopulse beam (Σ, ΔAZ, ΔEL). However, since there is a degree of freedom, the subarray division processing unit 12 is removed, and the monopulse beam (Σ, ΔAZ, ΔEL) can also be used as an input signal. In this case, the main beam shown in FIG. 12 corresponds to a monopulse beam or a subarray output calculated from the monopulse beam.

  FIG. 13 is a block diagram illustrating a configuration of a radar apparatus according to Embodiment 4 of the present invention. This radar apparatus is configured by adding an angle measuring unit 6 to the radar apparatus according to any one of the first to third embodiments. The angle measuring unit 6 calculates a target azimuth.

As a method for calculating the target direction, a null steering method using a subarray signal can be used. In this null steering system, components other than the extracted target signal Ys are set to 0, and null steering is performed on the subarray output Xs calculated by the equation (3). FIG. 14 is a diagram for explaining the principle of the null steering system. In this null steering system, the subarray is divided into two apertures, and the phase is null-steered within a predetermined angle measurement range according to the following equation, and the null direction with the lowest absolute value of Δ / Σ is the angle measurement value (detection) Direction).

here,
Xsn; target signal θb separated by ICA; beam peak direction j; imaginary unit k; wave number (2π / λ)
λ; wavelength dn; distance from the reference position of the nth element (n = 1 to N)
Wσn; complex weight of the nth element of the Σ beam bsrcσ; Wδn; complex weight of the nth element of the Δbeam bsrcδ; Aσn; amplitude weight of the Σbeam bsrcσ Aδn; amplitude weight of the Δbeam bsrcδ bsrccσ; At this time, if the distance between the sub-arrays is long, an ambiguity is generated at the null position, and a plurality of low-level points are generated. In order to suppress this ambiguity, as shown in FIG. 15, null steering is performed with a plurality of subarray sets (L), and if L out of L pieces have the same null direction, the direction is detected. It can be configured to be oriented.

  Next, the operation of the radar apparatus according to Embodiment 4 of the present invention will be described with reference to the flowchart shown in FIG. Note that steps that perform the same processing as that of the radar apparatus according to the first embodiment illustrated in FIG. 8 are denoted by the same reference numerals as those used in FIG.

  First, subarray input or monopulse input and subarray conversion are performed (step S31). In step S31, the processing of step S11 (see FIG. 8) of the radar device according to the first embodiment, or the processing of steps S21 and S22 (see FIG. 10) of the radar device according to the second or third embodiment. The same processing is executed.

  Next, ICA processing (step S12), signal extraction (step S13), signal identification (step S14), and distance measurement (step S15) are sequentially performed, and then angle measurement processing is performed. In the angle measurement process, first, determination based on the Δ beam level is performed (step S32). Next, it is checked whether or not the processing for the scanning range has been completed (step S33). If it is determined in step S33 that the process for the scanning range has not ended, the null direction is changed (step S34). Then, it returns to step S32 and the process mentioned above is repeated.

  If it is determined in step S33 that the process for the scanning range has been completed, it is then checked whether the processes for all subarrays have been completed (step S35). If it is determined in step S35 that the processing for all subarrays has not been completed, the processing is changed to execute processing for the next subarray (step S36). Then, it returns to step S32 and the process mentioned above is repeated.

  When it is determined in step S35 that the processing for all subarrays has been completed, orientation extraction is performed (step S37). That is, the angle measuring unit 6 sets the null direction having the lowest absolute value of Δ / Σ as the angle measurement value (detection direction). The measured angle value measured by the angle measuring unit 6 is output to the outside as the target direction.

  In the radar apparatus according to the first to fourth embodiments described above, the ICA processing unit 2 uses the complex ICA to separate the signals, but the radar apparatus according to the fifth embodiment of the present invention can reduce the computation scale. The signal is separated using a real number ICA.

  When the signal is separated using the real number ICA, the distance measurement by the distance measuring unit 5 can be performed with the real number ICA as it is, but a complex signal is required for the angle measurement. Therefore, in the radar apparatus according to the fifth embodiment, a Fourier transform is performed after the signal is separated, and then a complex signal is generated by a method of extracting only a positive (or negative) frequency.

First, in the case of the real number ICA, the following equation is used instead of the equation (5), for example, in the case of the FAST ICA algorithm (see p. 217 of Non-Patent Document 1). Other processes are the same as the processes according to the first to third embodiments.

here,
T; transposition ‖ ；; norm g; function g ′; derivative of g For example, as in the following equation (a is a constant).

  This ICA algorithm is an example, and other methods such as a method using kurtosis (fourth-order cumulant) (see Non-Patent Document 1) or the like can be used as an independent evaluation amount. Based on the result of this real number ICA, distance measurement is performed by the same method as the radar apparatus according to the first to third embodiments.

Next, in order to measure the angle, it is considered that the restored signal Y is converted into a complex number by the Hilbert transform shown in FIG. When the real number is simply expressed by coswt (sinwt), the complex number exp (jwt) is related by the following equation from Euler's formula. Euler's formula is described in, for example, “Matsuda, Introduction to Digital Signal Processing, Nikkan Kogyo Shimbun, p.119, 1984”.

here,
ω; 2πf
f; frequency t; time Thus, a complex number can be calculated from a real number by the following method. First, Y is Fourier transformed to extract only positive (negative) frequencies and inverse Fourier transformed. This is because a real number is a signal having a positive frequency and a negative frequency, whereas a complex number has either a positive or negative frequency. Using the complexized Y, the components other than the extracted target signal Ys are set to zero, the subarray output Xs is calculated by the equation (3), and the angle is measured by the same method as that of the radar apparatus according to the fourth embodiment.

  Next, the operation of the radar apparatus according to Embodiment 5 of the present invention will be described with reference to the flowchart shown in FIG. Note that steps that perform the same processing as that of the radar apparatus according to the first embodiment illustrated in FIG. 16 are denoted by the same reference numerals as those used in FIG.

  First, subarray input or monopulse input and subarray conversion are performed (step S31). Next, ICA processing (step S12), signal extraction (step S13), signal identification (step S14), and distance measurement (step S15) are sequentially performed, and then angle measurement processing is performed. In the angle measurement process, first, complex number conversion is performed (step S41). Next, determination based on the Δ beam level is performed (step S32). Next, it is checked whether or not the processing for the scanning range has been completed (step S33). If it is determined in step S33 that the process for the scanning range has not ended, the null direction is changed (step S34). Then, it returns to step S32 and the process mentioned above is repeated.

  If it is determined in step S33 that the process for the scanning range has been completed, it is then checked whether the processes for all subarrays have been completed (step S35). If it is determined in step S35 that the processing for all subarrays has not been completed, the processing is changed to execute processing for the next subarray (step S36). Then, it returns to step S32 and the process mentioned above is repeated.

  When it is determined in step S35 that the processing for all subarrays has been completed, orientation extraction is performed (step S37). That is, the angle measuring unit 6 sets the null direction having the lowest absolute value of Δ / Σ as the angle measurement value (detection direction). The measured angle value measured by the angle measuring unit 6 is output to the outside as the target direction.

  In the radar apparatus according to the fifth embodiment described above, the main purpose is to generate and process a complex number using the real number ICA. For conversion from the real number to the complex number, a method other than the above-described conversion is used. Can be used. Further, the distance is measured using the real number ICA, and the angle is measured after the complex number conversion. However, the distance measurement may be performed using the result obtained by the complex number conversion.

  Further, the present invention may not be pulsed as long as the target signal has a shape that can be identified as an unnecessary wave. Further, the present invention is not limited to a radar apparatus, and can be applied to a receiving apparatus when a signal that can be distinguished from an unnecessary wave is obtained as a target signal. Further, when measuring the disturbance azimuth, the direction of the separated continuous disturbance and pulse disturbance can be detected by the same method as the target signal.

  The present invention is applicable to a radar apparatus or a receiving apparatus that is required to reduce a processing scale or a circuit scale.

1 is a block diagram illustrating a configuration of a radar apparatus according to Embodiment 1 of the present invention. It is a figure which shows the structure of the antenna used with the radar apparatus which concerns on Example 1 of this invention. It is a figure which shows the observation variable input as an input signal into the radar apparatus which concerns on Example 1 of this invention. It is a figure which shows the structure of the antenna for acquiring an observation variable in the radar apparatus which concerns on Example 1 of this invention. It is a figure for demonstrating the electromagnetic wave environment to which the radar apparatus which concerns on Example 1 of this invention is applied. It is a figure for demonstrating ICA performed in the radar apparatus which concerns on Example 1 of this invention. It is a figure for demonstrating extraction and identification of the signal isolate | separated by the ICA process part in the radar apparatus which concerns on Example 1 of this invention. It is a flowchart which shows operation | movement of the radar apparatus which concerns on Example 1 of this invention. It is a figure which shows the structure of the antenna used with the radar apparatus which concerns on Example 2 of this invention. It is a flowchart which shows operation | movement of the radar apparatus which concerns on Example 2 of this invention. It is a figure which shows the structure of the antenna used with the radar apparatus which concerns on Example 3 of this invention. It is a figure which shows the structure of the antenna for acquiring an observation variable in the radar apparatus which concerns on Example 3 of this invention. It is a block diagram which shows the structure of the radar apparatus which concerns on Example 4 of this invention. It is a figure for demonstrating the principle of the null steering system employ | adopted in order to calculate a target azimuth | direction with the radar apparatus which concerns on Example 4 of this invention. It is a figure for demonstrating the null steering which suppresses ambiguity and calculates a target direction by the radar apparatus which concerns on Example 4 of this invention. It is a flowchart which shows operation | movement of the radar apparatus which concerns on Example 4 of this invention. It is a figure for demonstrating the Hilbert transformation performed in the radar apparatus which concerns on Example 5 of this invention. It is a flowchart which shows operation | movement of the radar apparatus which concerns on Example 5 of this invention. It is a figure for demonstrating the state of the signal in an unnecessary wave environment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 ICA process part 3 Signal extraction part 4 Signal recognition part 5 Distance measurement part 6 Angle measurement part 10 Circular aperture antenna 11 Small antennas 12 and 14 Subarray division | segmentation process part 13 Monopulse comparator

Claims (6)

A one-dimensional DBF (Digital Beam Forming) array antenna including a plurality of subarrays having different phase centers, which are arranged in one direction so as to form a circular opening and are divided in a direction orthogonal to the one direction;
By performing complex ICA (Independent Component Analysis) on the sub-array signals before monopulse synthesis sent from the plurality of sub-arrays of the one-dimensional DBF array antenna, the target signal and the unwanted wave signal are separated. An ICA processing unit;
A distance measuring unit for measuring a distance based on the target signal separated by the ICA processing unit;
A radar apparatus comprising: A one-dimensional DBF (Digital Beam Forming) array antenna including a plurality of subarrays having different phase centers, which are arranged in one direction so as to form a circular opening and are divided in a direction orthogonal to the one direction;
A subarray division processing unit that converts monopulse synthesized signals sent from a plurality of subarrays of the one-dimensional DBF array antenna into subarray signals before monopulse synthesis;
An ICA processing unit that separates a target signal and an unnecessary wave signal by performing complex ICA (Independent Component Analysis) on the subarray signal sent from the subarray division processing unit;
A distance measuring unit for measuring a distance based on the target signal separated by the ICA processing unit;
A radar apparatus comprising: An antenna that outputs a monopulse beam composed of a sum signal Σ, an AZ surface difference signal ΔAZ, and an EL surface difference signal ΔEL;
A subarray division processing unit that converts a monopulse beam output from the antenna into a subarray signal;
An ICA processing unit that separates a target signal and an unnecessary wave signal by performing complex ICA (Independent Component Analysis) on the subarray signal sent from the subarray division processing unit;
A distance measuring unit for measuring a distance based on the target signal separated by the ICA processing unit;
A radar apparatus comprising:   4. The angle measuring unit for detecting an azimuth by null steering using sub-array signals from a plurality of sub-arrays having different phase center intervals of the sub-arrays. Radar equipment.   The said ICA process part isolate | separates a target signal and an unnecessary wave signal by performing real number ICA with respect to the input subarray signal, The Claim 1 thru | or 3 characterized by the above-mentioned. Radar device. The ICA processing unit separates the target signal and the unwanted wave signal by performing real ICA on the input subarray signal,
5. The radar apparatus according to claim 4, wherein the angle measuring unit generates a complex signal from the separated real target signal and detects an azimuth by null steering based on the generated complex signal.

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