JP2005156276A - Radar system for target identification - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve target identification performance by narrowing down reference data, in a radar system for target identification for identifying observed targets. <P>SOLUTION: The radar system for target identification is provided with receiver 106 for receiving a plurality of polarization signals, through the use of a plurality of aerials having polarization characteristics difference from one another; a transmitter 101 for generating and transmitting wide-band pulses; a target detecting part 108 for detecting the targets, on the basis of a plurality of received polarization signals received by the receiver 106; and a target identifying part 109 for identifying the targets by combining the feature quantities. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radar apparatus for identifying a target using information on a target range profile and polarization in the field of radar.

  As a conventional technique related to a radar apparatus for performing target identification, there is a technique for identifying a target using a target range profile observed in a radar apparatus having a high range resolution. A library pre-stored as a reference range profile and means for calculating the correlation between the observed target range profile and the reference range profile stored in the library, and a reference highly correlated with the observed target range profile In the case where there is a range profile, it is disclosed that an observed target is identified as a target corresponding to the reference range profile (see Non-Patent Document 1, for example).

“Correlation Filters for Aircraft Identification From Radar Range Profiles”, IEEE Transactions on Aerospace and Electronic Systems, vol.29, no.3, pp.741-748, July 1993

  The conventional target identification radar device is configured as described above. However, when there are multiple targets with similar range profiles, a frequency band with a shorter wavelength than the target size such as a millimeter wave band is used. If so, the problem arises that these goals cannot be identified.

  The present invention has been made to solve the above-described problems. When there are a plurality of targets having similar range profiles, a frequency band having a short wavelength with respect to a target size such as a millimeter wave band is used. An object of the present invention is to obtain a target identification radar apparatus that can improve the target identification performance even in the case of such a situation.

  A radar device for target identification according to the present invention includes a transmitter that generates and transmits a broadband pulse, a receiver that receives a plurality of polarization signals using a plurality of antennas having different polarization characteristics, and A target detection unit that detects a target from a plurality of received polarization signals received by the receiver, a feature amount extraction unit that calculates a feature amount based on a signal from the target detection unit, and a feature amount extraction unit And a target identifying unit that identifies a target using a feature amount.

  According to the present invention, a plurality of types of indicators indicating the rough shape of the range profile of each polarization channel and a plurality of types of indicators indicating the relationship between the range profiles of the plurality of polarization channels are calculated, and the feature amounts are combined. By performing target identification, there is an effect that the probability of correctly identifying the target can be improved.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a target identifying radar apparatus according to Embodiment 1 of the present invention. Since the target range profile greatly depends on the target aspect angle (the angle between the target center line and the radar line-of-sight direction), for each candidate target, the range profile observed at any aspect angle is prepared as reference data. Must be stored in a library of candidate target range profiles.

  However, with this method, it is required to create and store reference data by changing the aspect angle in very fine steps for each candidate target, so that the library of candidate target range profiles becomes enormous. Occurs. In order to make the candidate target range profile library as small as possible, it is desirable to increase the increment of the aspect angle that is stored as reference data, but this time the candidate target range profile library is If the data does not include data that completely matches the aspect angle of the target, there arises a problem that the target identification performance deteriorates. Therefore, in this embodiment, the problem is solved by performing target identification by combining feature amounts.

Hereinafter, FIG. 1 will be described.
101 is a transmitter for transmitting a pulse signal, 102 is a transmission / reception switch for switching transmission / reception, 103 is a polarization switch, and 104 is a first polarization characteristic orthogonal to the polarization characteristic of the second polarization transmission / reception antenna 105. A single polarization transmission / reception antenna 105 is a second polarization transmission / reception antenna having a polarization characteristic orthogonal to the polarization characteristic of the first polarization transmission / reception antenna 104.

  Note that as the combinations in which the polarization characteristics of the first polarization transmitting / receiving antenna 104 and the second polarization transmitting / receiving antenna 105 are orthogonal, for example, a combination of vertical polarization and horizontal polarization, right-handed circular polarization and left-handed circular polarization, and the like. A combination of waves can be considered.

  A digital reception unit 106 performs phase detection and A / D conversion processing on the reception signals received by the first polarization transmission / reception antenna 104 and the second polarization transmission / reception antenna 105, and indicates the amplitude and phase of the polarization signal. It is a receiver that outputs a polarization signal (scattering matrix range profile described later).

  Reference numeral 107 denotes a received polarization signal storage unit that accumulates the scattering matrix range profile output from the receiver 106, and 108 denotes a target position detected from the scattering matrix range profile sent from the received polarization signal storage unit. A target detection unit 109 that cuts out a nearby scatter matrix range profile, 109 calculates a plurality of feature amounts from the scatter matrix range profile cut out by the target detection unit 108, and the feature amounts obtained here are accumulated in advance. A target identification unit 110 for identifying a target by comparing it with a library of feature quantities relating to known targets, and a display unit 110 for displaying the detection result and identification result of the target.

  109a is a polarization basis conversion processing unit that performs polarization basis conversion processing on the scattering matrix range profile sent from the target detection unit 108 to generate a range profile of a plurality of polarization channels, and 109b is obtained by 109a. 109c is a feature quantity extraction unit that calculates a plurality of feature quantities used for identification from a plurality of polarization channel range profiles, 109c is a feature quantity extraction unit that includes a polarization basis conversion processing unit 109a and a feature quantity calculation unit 109b, and 109d is known 109e is a reference target feature quantity library 109e that stores feature quantities related to the target, and is determined in advance from the feature quantities extracted by the feature quantity extraction unit 109c and the feature quantities accumulated in the reference target feature quantity library 109d. It is a determination unit that performs target identification in accordance with established rules.

FIG. 3 is an explanatory diagram showing the concept of a range profile.
In FIG. 3, a range profile is obtained by transmitting a pulse of an electromagnetic wave having a short wavelength, receiving a reflected wave reflected by a target, and recording it as a function of time. The range profile can be regarded as a projection of the spatial distribution of the target reflection coefficient in the direction of the line of sight of the radar.

The pulse transmitted at time t ₁ is incident on a strip-shaped region (distance resolution cell) having a pulse width w as shown in FIG. 3 at time t ₂ and reflected there. At a different time t ₃ , the transmission pulse enters another range bin as shown in the figure and is reflected there. Therefore, when the reflected wave from the target is received and recorded as a function of time, the reflected wave from each distance resolution cell can be recorded in order from the side closer to the antenna. In this way, the target range profile is observed.

Next, the scattering matrix range profile will be described.
The incident wave to the target and the scattered wave from the target are originally expressed as a vector in space, as is clear from Maxwell's equation. In particular, when the target is sufficiently far away in free space, these electromagnetic waves can be regarded as plane waves, so that the electric field (magnetic field) can be treated as a two-dimensional vector on a plane orthogonal to the traveling direction. . The state of time variation of these electric field (magnetic field) vectors in a plane wave is understood and classified as a concept of wave bias, that is, so-called polarization. When electromagnetic waves are expressed as vectors, the scattering characteristics of the observation target are not scalar values such as the radar cross section (Radar Cross Section: RCS), but the scattering matrix (Scattering Matrix) of Equations (1) and (2). ).

  The plane wave E (r, t) of the time t, the frequency f at the position vector r, and the wave vector k is expressed by the following equation.

Here, E ₀ is a complex electric field vector, which can be expressed by the following equation using a horizontal (horizontal: h) electric field component Eh and a vertical (vertical: v) electric field component Ev.

In equation (4), the vector [1, ρ] ^T (superscript T is transposed) characterizes the polarization state of the plane wave. Therefore, a vector E _{J in} which the Euclidean norm of [1, ρ] ^T is 1 is defined by the following equation.

Here, the superscript * represents a complex conjugate.
Hereinafter, the expression format of the electric field vector of Equation (4) is referred to as Jones Vector format.
Polarization state of the incident wave to the target, i.e. to represent the polarization state of transmit antennas at the complex electric field vector E _t of Jones Vector format. The vector E _s representing the polarization state of the scattered wave in this case is given by the following equation.

  In the above equation, S is a scattering matrix representing the scattering characteristics of the observation target, and is represented by the following equation.

here,
Shh is the H component of the scattered wave when the polarization of the incident wave is H,
Shv is the V component of the scattered wave when the polarization of the incident wave is H,
Svv is the V component of the scattered wave when the polarization of the incident wave is V,
Svh represents the H component of the scattered wave when the polarization of the incident wave is V.

The received voltage Vs when this scattered wave is received by a receiving antenna whose polarization state is given by a complex electric field vector _Er in the Jones Vector format is given by the following equation.

  Therefore, the received power Ps in this case is expressed as follows.

Here, in Equations (8) and (9), constant terms that are not affected by the polarization state are omitted.
It is known that the following equation holds when the transmission antenna and the reception antenna are monostatic.

  If the scattering matrix of the observation target can be observed, the range profile of the observation target can also be observed as the range profile of the scattering matrix.

FIG. 4 is an explanatory diagram showing the concept of the scattering matrix range profile, and FIG. 2 is a flowchart showing the target identification method according to the first embodiment.
That is, as shown in FIG. 4, a range profile similar to that shown in FIG. 3 can be obtained for each of the four elements Shh, Svh, Shv, Svv of the scattering matrix. These four range profiles are collectively referred to herein as a scattering matrix range profile. Or it is synonymous even if it considers that the scattering matrix for every distance resolution cell arranged in the distance direction as a scattering matrix range profile. In FIG. 4, for convenience of illustration, the range profile is shown in the form of electric field strength, but each element of the scattering matrix range profile is inherently a complex number.

Next, the operation will be described.
When the transmitter 101 generates a pulse signal as a broadband pulse, the transmission / reception switch 102 sends the pulse signal to the polarization switch 103, and the polarization switch 103 drives the first polarization transmitting / receiving antenna 104, The pulse signal is radiated from the first polarization transmitting / receiving antenna 104 to the space. Hereinafter, a case will be described in which the polarization characteristics of the first polarization transmitting / receiving antenna 104 and the second polarization transmitting / receiving antenna 105 are horizontal polarization and vertical polarization, respectively.

The pulse signal radiated into the space from the first polarization transmitting / receiving antenna 104 is scattered by the observation target.
The polarization switching unit 103 drives both the first polarization transmission / reception antenna 104 and the second polarization transmission / reception antenna 105, so that the first polarization transmission / reception antenna 104 and the second polarization transmission / reception antenna 105 are scattered by the observation target. When the scattered waves are received, the first polarization transmitting / receiving antenna 104 and the second polarization transmitting / receiving antenna 105 send the received signal to the receiver 106, and the receiver 106 receives the first polarization transmitting / receiving antenna 104 and the second polarization. Digital detection signals S ₁₁ (m) and S ₂₁ (m) indicating the amplitude and phase of each received signal by performing phase detection processing and A / D conversion processing on each received signal received by the transmitting / receiving antenna 105. Is output (step ST1).

S _ij (m) is the m-th (m = 1, 2,..., M) sample value of the received signal transmitted by the j-th polarization transmission / reception antenna and received by the i-th polarization transmission / reception antenna. It is. Here, M is the number of samples. Similarly, the broadband pulse generated by the transmitter 101 is sent to the polarization switching unit 103 via the transmission / reception switch 102, and the target is irradiated from the second polarization transmitting / receiving antenna 105 to the first polarization transmitting / receiving antenna 105. By repeating the same processing as the received signal received by the second polarization transmitting / receiving antenna 106, the received signals S ₁₂ (m) and S ₂₂ (m) are obtained (step ST1).

FIG. 5 is an explanatory diagram showing operation modes at each time of the first polarization transmitting / receiving antenna and the second polarization transmitting / receiving antenna.
The operation modes of the first polarization transmission / reception antenna 104 and the second polarization transmission / reception antenna 105 are shown, and the intervals of the received signals S ₁₁ (m), S ₂₁ (m), S ₁₂ (m), S ₂₁ (m) are shown. It is a batch of processing required to obtain a set.

The received polarization signal storage unit 107 temporarily stores the obtained received signals S ₁₁ (m), S ₂₁ (m), S ₁₂ (m), and S ₂₂ (m). Is a reception scattering matrix range profile having a value of the scattering matrix Sm (m = 1, 2,..., M) in each resolution cell, and is expressed as in Expression (11).
Hereinafter, the combination of the polarization states of the transmission antenna and the reception antenna may be referred to as a polarization channel.

Next, the target detection unit 108 detects a target from the received scattering matrix range profile.
Here, for example, the target detection performance may be improved by suppressing clutter by a method such as PWF (Polarimetric Whitening Filter) or PNF (Polarimetric Notch Filter). Further, the target detection unit 108 cuts out the sample Sm (m = M ₀ , M ₀ +1,..., M ₀ + M _T −1) near the detected target position (step ST2).

The number M _T of samples to be cut out here can be determined in advance from information such as the size of a target assumed as an observation target.
First, the basis conversion processing unit 109a applies to the target reception scattering matrix range profile Sm (m = M ₀ , M ₀ +1,..., M ₀ + M _T −1) extracted by the target detection unit 108. Polarization basis conversion shown in equation (12) or polarization component decomposition exemplified in equation (13) is performed (step ST3).

Here, V is a unitary matrix, and the superscript * T represents the conjugate transpose of the matrix.
An arbitrary unitary matrix can be set according to the purpose.
The same observation is performed with a combination of two orthogonal polarizations different from the orthogonal polarization combination of the first polarization transmission / reception antenna 104 and the second polarization transmission / reception antenna 105 by the polarization basis conversion represented by the equation (12). Scattering matrix range profile Um (m = M ₀ , M ₀ +1,..., M ₀ + M _T −1) is obtained.

Alternatively, for example, by using the polarization component decomposition expressed by Equation (13), the odd-numbered reflection component K _o (m) that has reached the transmitting / receiving antenna after being reflected an odd number of times in the target of the received wave, and the even number in the target The even-numbered reflection component K _e (m) that reaches the transmission / reception antenna after being reflected once, and the polarization component (cross component) K _c (m) orthogonal to the incident wave that is generated when reflected by the target are obtained.

As described above, it is possible to obtain a range profile for any type of polarization channel by performing various polarization basis conversions and polarization component decomposition.
The set of range profiles obtained here is hereinafter referred to as a target multi-polarization channel range profile. Here, the “polarization channel” includes not only a combination of transmission polarization and reception polarization but also polarization components such as K _o , K _e , and K _c (the same applies hereinafter).
Next, the feature quantity calculation unit 109b calculates a feature quantity defined below from the multiple polarization channel range profile obtained by the above-described base conversion process (step ST4).

In Expression (14), P (m) represents the power value of a signal of a certain polarization channel. For example, the polarization channel of horizontal polarization transmission horizontal polarization reception is defined as Expression (15). Is done. r _g is the gravity center, is defined by the equation (16). Xp represents the Fourier spectrum of the range profile of the polarization channel p.

  In the equation (14), the second-order and third-order cross moment spectra are exemplified by the polarization channels 1 and 2, and the polarization channels 1, 2, and 3, respectively, but obtained by the basis conversion processing unit 109a. It is possible to calculate for all combinations of polarization channels.

FIG. 6 is an explanatory diagram showing definitions of the average, standard deviation, maximum value, and moment around the center of gravity among the feature amounts calculated by the feature amount calculation unit.
The feature amount is calculated by the feature amount calculation unit 109b, the average value is the average reflection intensity of each polarization channel, the maximum value is the maximum reflection intensity, the standard deviation is the complexity of the range profile shape of each polarization channel, the center of gravity It can be seen that the surrounding moment is an index mainly representing the length of the range profile.

  Furthermore, from equation (14), the normalized moment around the center of gravity and bispectrum show the distribution of points with strong scattering intensity on the range profile, and the cross moment spectrum shows the relationship between the range profiles of multiple polarization channels. It can be said that each is an indicator. Summarizing the above, the feature quantity shown in Equation (14) can be broadly classified into an index indicating the rough shape of the range profile of each polarization channel and an index indicating the relationship between the range profiles of a plurality of polarization channels.

  In the reference target feature amount library 109d, feature amounts extracted from N types of target scattering matrix range profiles observed in advance in the same manner are stored. Smn can be obtained from theoretical calculations (for example, GTD: Geometrical Theory of Diffraction) in addition to prior observations.

  The determination unit 109e compares the N-type target feature quantities stored in the reference target feature quantity library 109d, and identifies the target according to a predetermined rule (step ST5).

For example, when the number of feature quantities used for identification is L, L feature quantities relating to each target are accumulated in the reference target feature quantity library 109d in the form of L-dimensional feature quantity vectors and extracted from the received signal. After constructing an L-dimensional feature quantity vector from the L feature quantities, the Euclidean distance between the L-dimensional feature quantity vector of the received signal and the feature quantity vector of each reference target is calculated, and the reference distance is the shortest. A method of determining that the type is the same as the target is conceivable.
Finally, the display unit 110 displays the outputs of the target detection unit 108 and the determination unit 109e.

  According to the first embodiment, since a plurality of types of indexes indicating relationships between range profiles of a plurality of polarization channels are calculated, and the target identification is performed by combining the feature amounts, the probability of correctly identifying the target From the scattering matrix range profile for target identification, the rough shape of the range profile of each polarization channel is shown as a feature quantity with small variation due to movement of the target in the distance direction and change of the aspect angle By using a plurality of types of indexes, there is an effect that the amount of library memory and the amount of calculation processing can be reduced.

Embodiment 2. FIG.
FIG. 7 is a block diagram showing the configuration of the target identifying radar apparatus according to Embodiment 2 of the present invention, and 109f is a weight determined on the basis of a previous observation result for the feature quantity extracted by the feature quantity extraction unit 109c. It is a weighting unit for applying a coefficient.

In general, it is expected that the combination of feature quantities effective in reducing the angle dependency varies depending on the target to be identified. Therefore, the feature quantities C _i (i = 1, 2,. .., L: It is desirable to select and combine appropriate ones from among L (the total number of feature values), or perform appropriate weighting.

If the target to be identified is known, the weighting coefficient w _i (i = 1, 2,...) That increases the probability of the most correct identification when performing feature extraction by observation in advance. , L). The weighting unit 109f weights the feature amount extracted by the feature amount extraction unit 109c according to the following equation. If the value of the weighting coefficient is 0, it means that the corresponding feature amount is not selected.

  Here, the feature amount means the average power of each polarization channel signal, the standard deviation of each polarization channel signal, the maximum value of each polarization channel signal, the moment around the center of gravity of each polarization channel signal, and each polarization. It represents a normalized moment around the center of gravity of the channel signal, a higher-order spectrum of each polarization channel signal, a cross moment spectrum of the plurality of polarization channel signals, and the like.

It should be noted that a plurality of combinations of weighting coefficients w _i (i = 1, 2,..., L) are prepared in accordance with the target type to be processed, and an operator selects a combination of weighting coefficients suitable for the operation. By selecting, versatility can be ensured.

  According to the second embodiment, since an appropriate weight can be added to the feature amount depending on the target to be identified, there is an effect that the probability of correctly identifying the target can be improved.

Embodiment 3 FIG.
FIG. 8 is a block diagram showing a configuration of a target identifying radar apparatus according to Embodiment 3 of the present invention. 109g selects a polarization channel to be used for identification according to the signal-to-noise power ratio of each polarization channel. It is a polarization channel selector.

  The polarization channel selection unit 109g obtains the average power of each polarization channel, and then compares this with the known receiver noise level, and the average power of the polarization channel whose average power is lower than α times the receiver noise level. The data is not sent to the feature amount calculation unit 109b.

  According to the third embodiment, since data of a polarization channel having a low signal-to-noise ratio can be excluded, there is an effect of reducing the target misidentification probability due to the influence of noise.

Embodiment 4 FIG.
9, FIG. 10 and FIG. 11 are block diagrams showing the configuration of a target identifying radar apparatus according to Embodiment 4 of the present invention.

  9, 10, and 11, when a plurality of hit observation values are obtained, 109h compares the discrimination results in the respective hit signals, and outputs the most result as the final discrimination result, 109i is a range profile average processing unit that averages the scattering matrix range profile obtained with each hit signal when multiple hit observations are obtained, and 109j is a multiple hit observation value obtained. A feature amount average processing unit that calculates an average value for each feature amount from the feature amounts extracted for each hit in the feature amount extraction unit 109c. 111 is a scatter in each hit signal when multiple hit observation values are obtained. It is a received polarization signal storage unit for multiple hits that stores matrix range profiles.

When multiple hits are obtained, there are two main methods. This is a method of selecting a determination result that seems to be most appropriate after determining each hit in the determination unit 109e and a method of averaging the input values to the determination unit 109e in advance.
Here, FIG. 9 shows a configuration embodying the former, and FIGS. 10 and 11 show configurations embodying the latter method.

First, the operation of the majority decision unit 109h in the configuration of FIG. 9 will be described. When the number of hits used for observation is H, the determination unit 109e outputs H target identification results.
When these identification results are not all equal, the majority decision unit 109h outputs the largest number as the final target identification result. Alternatively, according to a predetermined rule, the identification result and the accuracy for the result may be output at the same time.

  For example, when 10 hits are observed, if the determination result of the determination unit 109e is the target A5 times, the target B3 times, and the target C2 times, the majority decision unit 109h outputs “the target is A” Alternatively, “50% probability of target A, 30% probability of target B, 20% probability of target C” may be output.

Next, the operation of the range profile average processing unit 109i in the configuration of FIG. 10 will be described.
When the hit number used for the observation is H, the multiple hit received polarization signal storage unit 111 stores H scattering matrix range profiles Sm, h (m = 1, 2,..., M; h = 1, 2, ..., H) are accumulated.

  The range profile average processing unit 109i averages these scattering matrix range profiles accumulated in the multiple hit received polarization signal storage unit 111 according to the following equation, and the obtained averaged scattering matrix range profile is sent to the feature amount extraction unit 109c. send.

Here, θ _h (h = 1, 2,..., H) is a correction term for correcting the amount of phase change due to the movement of the platform.
Next, the operation of the feature amount average processing unit 109j in the configuration of FIG. 11 will be described. The feature quantity average processing unit 109j obtains L feature quantities C _{i, h} (i = 1, 2,..., L: L is the total number of feature quantities) for each hit obtained by the feature quantity extraction unit 109c; h = 1, 2,..., H) are averaged according to the following equation, and the obtained average feature amount is sent to the determination unit 109e.

  According to the fourth embodiment, since the amount of data can be increased by performing observation a plurality of times, there is an effect that the probability of correctly identifying the target can be improved.

Embodiment 5 FIG.
FIG. 12 is a block diagram showing the configuration of the target identifying radar apparatus according to the fifth embodiment of the present invention. Reference numeral 115 denotes a target movement trajectory calculation unit. Reference numerals 1-110 are the same as those described in the first embodiment. The description of the same parts as those of the first embodiment is based on the description of the first embodiment.

  The target movement trajectory calculation unit 115 receives the signal obtained by detecting the target from the received polarization signal by the target detection unit 108, captures the target movement vector that changes every moment as a wake, calculates the attitude of the target, and refers to the target characteristics On the other hand, 109 calculates a plurality of feature amounts from the scattering matrix range profile extracted by the target detection unit 108, and the feature amounts obtained here are a library of feature amounts relating to known targets accumulated in advance. It has a target identification unit that identifies the target by comparing with.

For example, when the number of feature quantities used for identification is L, L feature quantities relating to each target are accumulated in the reference target feature quantity library 109d in the form of L-dimensional feature quantity vectors and extracted from the received signal. After constructing an L-dimensional feature quantity vector from the L feature quantities, the Euclidean distance between the L-dimensional feature quantity vector of the received signal and the feature quantity vector of each reference target is calculated, and the reference distance is the shortest. A method of determining that the type is the same as the target is conceivable.
Finally, the display unit 110 displays the outputs of the target detection unit 108 and the determination unit 109e.

  Here, the feature amount includes an average power of each polarization channel signal, a standard deviation of each polarization channel signal, a maximum value of each polarization channel signal, a moment around the center of gravity of each polarization channel signal, and the like.

  According to the fifth embodiment, from the scattering matrix range profile for target identification, a plurality of types of indicators indicating the rough shape of the range profile of each polarization channel, and the range profiles of the plurality of polarization channels are used as features. Since a plurality of types of indices indicating the relationship between them are calculated and the target identification is performed by combining the feature amounts, the probability of correctly identifying the target can be improved.

Embodiment 6 FIG.
FIG. 13 is a block diagram showing the configuration of a target identifying radar apparatus according to Embodiment 6 of the present invention. Reference numeral 112 shows a target received polarization signal imaged as a polarization characteristic by the target detector 108, and then the target is detected. The target feature quantity to be referred to is narrowed down, while 109 calculates a plurality of feature quantities from the scattering matrix range profile extracted by the target detection unit 108, and the obtained feature quantities are calculated in advance. The target is identified by comparing it with a library of feature quantities related to the accumulated known target.

  According to the sixth embodiment, in order to image the target polarization characteristics to be identified, the posture angle can be grasped from the shape of the object itself, so that more appropriate weighting is added to the feature amount. Or since it can select, the effect which can improve the probability which identifies a target correctly is produced.

Embodiment 7 FIG.
FIG. 14 is a block diagram showing the configuration of a target identifying radar apparatus according to Embodiment 7 of the present invention. Reference numeral 113 denotes a target detected by the target detecting unit 108 using the received polarization signal, and the detected neighborhood. The target RCS (radar reflection area) data is calculated from the result of cutting out the range profile, and based on the RCS data, the target posture is obtained by the RCS data determined based on the previous observation result and the pattern matting method. The target feature amount to be referred to is narrowed down, while 109 calculates a plurality of feature amounts from the scattering matrix range profile cut out by the target detection unit 108, and the obtained feature amounts are stored in advance as known features. The target is identified by comparing it with a library of feature values for the target.

  According to the seventh embodiment, since reference data for calculating a target posture can be easily secured, the calculation load is low, and the probability of target identification using feature quantities is improved for every target. There is an effect that can.

Embodiment 8 FIG.
FIG. 15 is a block diagram showing the configuration of a target identification radar apparatus according to Embodiment 8 of the present invention. Reference numeral 109 denotes a target identification unit for calculating a plurality of feature amounts from the scattering matrix range profile extracted by the target detection unit 108. On the other hand, 114 performs polarization basis conversion processing on the received polarization signal cut out by the basis conversion processing unit 109a to obtain a plurality of polarization channel signals to obtain a one-time reflection component, two-time reflection component, and multiplexing. It is decomposed into three basic components of the reflection component, the target posture is calculated from each contribution rate, the target feature amount to be referred to is narrowed down, and the feature amount obtained by the target identification unit 109 is accumulated in advance. The basic component three-component contribution rate calculation unit for identifying a target by comparing it with a library of feature amounts related to a known target.

  According to the eighth embodiment, the accuracy of the target polarization characteristic to be identified is improved, and the result is reflected in the attitude angle calculation accuracy. Therefore, more appropriate weighting is added to the feature amount. Or, since it can be selected, it is possible to improve the probability of correctly identifying the target.

It is a block diagram which shows the structure of the radar apparatus for target identification by Embodiment 1 of this invention. It is a flowchart which shows the target identification method by Embodiment 1 of this invention. It is explanatory drawing which shows the concept of a range profile. It is explanatory drawing which shows the concept of a scattering matrix range profile. It is explanatory drawing which shows the operation mode in each time of a 1st polarized wave transmission / reception antenna and a 2nd polarization transmission / reception antenna. It is explanatory drawing which shows the definition of an average, a standard deviation, a maximum value, and the moment around a gravity center among the feature-values calculated in a feature-value calculation part. It is a block diagram which shows the structure of the radar apparatus for target identification by Embodiment 2 of this invention. It is a block diagram which shows the structure of the radar apparatus for target identification by Embodiment 3 of this invention. It is a block diagram which shows the structure of the radar apparatus for target identification by Embodiment 4 of this invention. It is a block diagram which shows the structure of the radar apparatus for another target identification by Embodiment 4 of this invention. It is a block diagram which shows the structure of the radar apparatus for target identification other than FIG. 9 or FIG. 10 by Embodiment 4 of this invention. It is a block diagram which shows the structure of the radar apparatus for target identification by Embodiment 5 of this invention. It is a block diagram which shows the structure of the radar apparatus for target identification by Embodiment 6 of this invention. It is a block diagram which shows the structure of the radar apparatus for target identification by Embodiment 7 of this invention. It is a block diagram which shows the structure of the radar apparatus for target identification by Embodiment 8 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 Transmitter, 102 Transmission / reception switch, 103 Polarization switch, 104 1st polarization transmission / reception antenna, 105 2nd polarization transmission / reception antenna, 106 receiver, 107 Reception polarization signal memory | storage part, 108 Target detection part, 109 Target Identification unit, 109a basis conversion processing unit, 109b feature quantity calculation unit, 109c feature quantity extraction unit, 109d reference target feature quantity library, 109e determination unit, 109f weighting unit, 109g polarization channel selection unit, 109h majority decision unit, 109i range Profile average processing unit, 109j feature quantity average processing unit, 110 display unit, 111 multiple hit received polarization signal storage unit, 112 target image generation unit, 113 · RCS calculation unit, 114 · basic configuration three component contribution rate calculation unit, 115 Target movement track calculation unit.

Claims (13)

A transmitter that generates and transmits wideband pulses; and
A receiver that receives a plurality of polarization signals using a plurality of antennas having different polarization characteristics from each other; a target detection unit that detects a target from a plurality of received polarization signals received by the receiver;
A feature amount extraction unit that calculates a feature amount based on a signal from the target detection unit;
A target identifying radar apparatus comprising: a target identifying unit that identifies a target using the feature amount extracted by the feature amount extracting unit. 2. The target identifying radar apparatus according to claim 1, wherein the feature quantity extraction unit calculates a feature quantity by calculating a plurality of polarization channel signals from a plurality of received polarization signals received. 3. The target identifying radar apparatus according to claim 1, wherein the feature amount extracting unit calculates a feature amount that is small in variation due to movement of the target in the distance direction and change in the aspect angle. 4. The target is identified by comparing the feature quantity extracted by the feature quantity extraction unit with a library of feature quantities relating to known targets accumulated in advance. The radar device for target identification according to 1. The target identification unit is configured to identify a target after adding an appropriate weight to each feature amount based on the reliability of the feature amount determined based on a previous observation result as the target identification unit. The radar device for target identification according to any one of claims 1 to 4. The target identification is performed by using a signal of a polarization channel obtained by removing a signal whose average power is equal to or lower than a certain level with respect to known noise power in advance as the target identification unit. The radar device for target identification according to any one of 5. The feature amount extraction unit calculates the feature amount from the received multiple hit signals, and the target identification unit obtains all or part of the feature amounts calculated by the feature amount extraction unit for each hit signal. Claims 1 to claim, further comprising: a majority voting unit that aggregates the identification results for each hit signal and outputs the most frequent identification result as a final identification result after identifying the target. The radar device for target identification according to any one of 6. 2. The feature quantity extracting unit, after averaging a plurality of received hit signals in the hit direction to calculate an average received polarization signal, calculating the feature quantity from the average received polarization signal. The target identifying radar apparatus according to claim 7. The said feature-value extraction part calculates the said feature-value from the received multiple hit signal, Then, averages each feature-value in the hit signal direction, The any one of Claims 1-8 characterized by the above-mentioned. Target identification radar device. A target movement track calculation unit for calculating a movement track of the detected target and determining a posture of the target;
2. The target identifying radar apparatus according to claim 1, wherein the feature quantity extraction unit calculates a feature quantity by calculating a plurality of polarization channel signals from a plurality of received polarization signals received. The target identification unit includes a target image generation unit that images a plurality of received polarization signals received and calculates a target attitude, and is a comparative feature suitable for a feature amount determined based on a previous observation result 11. The target identifying radar apparatus according to claim 1, wherein the target identifying ability is improved by selecting a quantity. As the target identification unit, an RCS (radar reflection area) is calculated from a plurality of received polarization signals received, and an RCS calculation unit for determining a target attitude is provided. The target identification radar apparatus according to any one of claims 1 and 3 to 11, wherein an appropriate comparison feature amount is selected to improve target identification capability. As the target identification unit, three types of basics for performing base conversion processing from a plurality of received polarization signals received, decomposing the components into three types of basic components, calculating respective contribution rates, and calculating a target attitude A basic configuration 3 component contribution rate calculation unit that calculates the contribution rate of the component of the configuration is selected, and appropriate comparison feature amounts are selected with respect to the feature amounts determined based on the previous observation results, and the target discrimination ability is increased. 13. The target identifying radar apparatus according to claim 1, wherein the target identifying radar apparatus is improved.

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