JP3580270B2 - Target classification device and radar device having the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a target classification device that classifies targets into, for example, missiles, small aircraft, large aircraft, and the like, and a radar device including the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known a radar device that classifies targets detected during a search into missiles, small aircraft, large aircraft, and the like (for example, Japanese Patent Application Laid-Open No. H5-157839).
[0003]
FIG. 5 is a block diagram showing a conventional radar apparatus of this type. Hereinafter, description will be made based on this drawing.
[0004]
A conventional radar device 11 includes an antenna 1 for transmitting and receiving radar radio waves, a wideband modulation signal generating unit 10 for generating a signal that has been subjected to wideband modulation in order to improve the resolution in the range (distance) direction, and amplifying and amplifying the wideband modulation signal. A radar transmitting unit 9 for frequency-converting and generating a radar transmission signal, a circulator 8 for switching transmission / reception signals, a switching unit 2 for switching between wideband reception processing and narrowband reception processing, and a reception processing in a narrowband reception system. Receiving unit 3, a radar signal processing unit 5 for performing signal processing, a wideband receiving unit 4 for receiving a reflected signal from a target in a wideband receiving system, and a wideband for high-pulse compression of a signal received in a wideband. And a signal processing unit 6.
[0005]
The wideband signal processing unit 6 achieves a distance resolution of about 1.5 m by performing high pulse compression in a band of about 100 MHz, and performs target classification. In this classification processing, since the range resolution is greatly increased, the processing calculation amount in the range direction increases. Therefore, processing is performed only in the vicinity of the range in which the target is sent in advance from the radar signal processing unit 5 so that the processing is completed in time so that the normal search and tracking are not affected. .
[0006]
[Problems to be solved by the invention]
The first problem is that a frequency band of 100 MHz is required. That is, a frequency band of as much as 100 MHz is allocated to one radar device. Therefore, a means for performing target classification using a narrower frequency band is required.
[0007]
A second problem is that there is no correction circuit due to a change in the target posture. As a result, the received power fluctuated significantly with respect to the target fluctuation. Further, even when a high-range resolution radar is used, classification is difficult because the reception characteristics in the range direction change according to the estimated angle with respect to the target radar.
[0008]
[Object of the invention]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a target classification device capable of realizing accurate classification processing even in a narrow frequency band, and a radar device provided with the target classification device.
[0009]
[Means for Solving the Problems]
A target classifying apparatus according to the present invention is configured to input a range profile indicating a target range vs. RCS characteristic and target tracking information and output a type of a target, and to estimate a target length from the range profile. , A pattern recognition unit that performs range profile pattern recognition while considering tracking information, and a categorization process that performs categorization processing based on the target length estimated by the target length estimation unit and the range profile recognized by the pattern recognition unit. And a part. Then, the target length is estimated using a plurality of formulas (described later) corresponding to the range profile shape (claims 1 to 3).
[0010]
An average processing unit that calculates RCS from received power for each hit, obtains an average value of these RCSs, and corrects a range profile may be further provided ( Claim 4 ). Target length estimator unit may be varied according to the correction term included in the total formula to the magnitude of the resolution (claim 5).
[0011]
A radar device according to the present invention includes the target classification device according to any one of claims 1 to 5 ( claim 6 ). For example, an antenna that transmits and receives radar radio waves, a wideband modulation signal generator that generates a signal that is broadband modulated to improve the resolution in the range direction, and a radar that amplifies and frequency converts the wideband modulation signal to generate a radar transmission signal A transmitting unit, a circulator for switching transmission / reception signals, a switching unit for switching between a wideband reception system and a narrowband reception system, a radar reception unit for performing reception processing in the narrowband reception system, and a signal in the narrowband reception system. A radar signal processing unit for processing, a wideband receiving unit for receiving a reflected signal from a target in a wideband receiving system, a wideband signal processing unit for high-pulse compressing a signal received in a wideband in the wideband receiving system, and a high-pulse compression the claims 1 to 5 conduct the target classification process on the basis of the range profile and tracking information resolution in the range direction is improved It is obtained and a target classification apparatus according to any displacement (claim 7).
[0012]
In other words, the radar apparatus according to the present invention performs target classification by using track information obtained from a range profile and tracking information, and improves the resolution in the range direction by providing a radar signal processing unit that provides tracking information. A wideband modulation signal generating section for generating a wideband modulated signal, a wideband receiving section for receiving a reflected signal from a target, a wideband signal processing section for compressing a wideband received signal with a high pulse, and a high pulse A target classifying apparatus is provided which estimates a target length based on a range profile obtained as a change in RCS in the range direction and performs pattern recognition based on a range profile obtained as a change in RCS in the range direction due to compression. In addition, the target classification device has a function of reducing the influence of a change in the range profile due to a change in the posture of the target.
[0013]
When the target is detected in the narrowband receiving system and, for example, the operator determines that classification is necessary, the radar signal processing unit outputs a classification request signal to the wideband modulation signal generation unit and the switching unit. Then, the wideband modulation signal generating section supplies a wideband radio wave necessary for high-range resolution to the radar transmitting section and outputs it from the antenna. At the same time, the switching unit switches the connection to the broadband receiving system that performs the classification process. The broadband received signal received by the antenna 1 is amplified and detected by the wideband receiving unit, and the resolution in the range direction is increased by the high pulse compression in the wideband signal processing unit, so that the range profile indicating the target range versus RCS characteristic is calculated. Used. The classification processing unit performs a target classification process based on the stable range profile and the target tracking information by using a means for reducing the fluctuation of the range profile. As a result, the target classification is realized using the feasible frequency band and the range profile indicating the target range-RCS characteristic and the wake information.
[0014]
Therefore, in the radar apparatus, the resolution in the range direction is improved by high-pulse compression in a frequency band of about 30 MHz, and target classification is performed based on characteristics (range profile) obtained as a change in RCS in the range direction and track information obtained from tracking information. A target classification device for performing processing can be provided.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram showing an embodiment of a radar device according to the present invention. Hereinafter, description will be made based on this drawing.
[0016]
The radar device 12 according to the present embodiment includes an antenna 1 for transmitting and receiving radar radio waves, a wideband modulation signal generating unit 10 for generating a signal that has been subjected to wideband modulation to improve the resolution in the range direction, and amplifying and frequency-modulating the wideband modulation signal. A radar transmitting unit 9 for converting and generating a radar transmission signal, a circulator 8 for switching between transmission and reception signals, a switching unit 2 for switching between wideband reception processing and narrowband reception processing, and a reception processing in a narrowband reception system. A radar receiving unit 3 for performing signal processing, a radar signal processing unit 5 for performing signal processing, a wideband receiving unit 4 for receiving a reflected signal from a target in a wideband receiving system, and a wideband signal for compressing a signal received in a wideband with a high pulse. A processing unit 6 and a target classification device 7 for performing target classification processing based on the range profile and the wake information whose resolution in the range direction is improved by high pulse compression. Eteiru. This range profile is obtained as a change in RCS in the range direction.
[0017]
FIG. 2 is a block diagram illustrating an example of the target classification device 7. Hereinafter, description will be made based on this drawing.
[0018]
The target classifying device 7 includes a target length estimating unit 71 for estimating a target length from a range profile, a pattern recognizing unit 72 for recognizing a range profile pattern in consideration of wake information, and calculating RCS from received power for each hit. An averaging unit 73 that obtains an average value from the 50% points by using these as a histogram, and a classification unit 74 that performs a classification process based on the information and the wake information from the target length estimation unit 71 and the pattern recognition unit 72 are provided. I have.
[0019]
Next, the operation of the radar device 12 will be described with reference to FIG.
[0020]
The radio wave radiated from the antenna 1 is reflected by the target and received by the antenna 1 again. In normal operation, since the switching unit 2 is connected to the narrow band receiving system, the received signal is amplified and detected by the radar receiving unit 3 and subjected to signal processing such as pulse compression by the radar signal processing unit 5. Then, target detection and tracking are performed.
[0021]
When the target is detected and, for example, the operator determines that "classification is required", the radar signal processing unit 5 outputs a classification request signal to the wideband modulation signal generation unit 10 and the switching unit 2. The broadband modulation signal generator 10 supplies a wideband radio wave that can be realized at a high frequency of about 30 MHz, for example, to the radar transmitter 9 and outputs it from the antenna 1. The switching unit 2 switches the connection to the broadband receiving system that performs the classification process.
[0022]
The wideband reception signal received by the antenna 1 is amplified and detected by the wideband reception unit 4, the resolution in the range direction is increased by high pulse compression by the wideband signal processing unit 6, and the target range vs. RCS as shown in FIG. A range profile indicating the characteristic is calculated. The target classification device 7 classifies targets by performing classification processes such as calculation of a target length and pattern recognition based on the range profile and the track information obtained from the tracking information of the targets.
[0023]
FIG. 3 is a graph showing a range profile. FIG. 3 [1] shows a case of a missile, and FIG. 3 [2] shows a case of an aircraft. FIG. 4 is an explanatory diagram illustrating a change in the target length depending on the estimated radar angle. Hereinafter, the operation of the target classification device 7 will be described with reference to FIGS.
[0024]
Range profile information as shown in FIG. 3 is input to the target length estimating unit 71 and the pattern recognizing unit 72. The range profile for a monotonous shape such as a missile is as shown in FIG. A range profile for a complicated shape such as an aircraft having a main wing and a tail wing is as shown in FIG. 3 [2]. When the frequency band is, for example, about 30 MHz, the range resolution is about 5 m, and a sufficient resolution cannot be obtained. However, the accuracy of the target classification can be increased by using a plurality of target classification means and correction processing means.
[0025]
In the present invention, the target classification means includes a target length estimation means, a range profile pattern recognition means, and a means for comprehensively classifying the target from the target length estimation result, the pattern recognition result, and the track information. The correction processing means includes a circuit that corrects target length using wake information, corrects pattern recognition reference data, and reduces fluctuations in received power due to fluctuations in target attitude. The details of the above means will be described below.
[0026]
The pattern recognition unit 72 performs target classification by performing pattern matching processing such as correlation with pre-stored classification reference data, for example, based on differences in range profile characteristics due to differences in target shapes. The part of the range profile that can be actually confirmed by the radar is a portion that is equal to or higher than the threshold level determined by the S / N ratio. Therefore, as shown in FIG. 3, a sufficient S / N ratio is required to estimate the target length from the range profile. Therefore, if the S / N ratio is insufficient when the classification request signal is output from the radar signal processing unit 5, the S / N ratio is improved by means such as multi-hit integration while switching to a wideband receiving system. . That is, the number of transmission hits of the wideband modulation signal generation unit 10 is increased, and the integration process in the wideband signal processing unit 6 is performed.
[0027]
The target length estimating unit 71 obtains a signal range Ls equal to or higher than the threshold level for a single peak, for example, as in the range profile in FIG. 3A, according to the shape of the range profile. Xa and Xb are obtained for a sample having a plurality of peaks, such as the range profile of [2]. Then, the target estimated length is calculated using, for example, the following equation.
[0028]
L = Ls−2La−La / √3 + C1 (1) Equation L = Xb−Xa + La / √3 + C2 (2) Equation L: Target Estimated Length La: Range Resolution Ls: Range Profile Length Above Threshold Xa: First Peak Range Xb: last peak range C1, C2: correction term
Equation (1) is an equation for calculating the target estimated length for a range profile having one peak. Equation (2) is an equation for calculating the target estimated length for a plurality of range profiles having peaks. In both equations (1) and (2), the third term is the correction of the range quantization error. Table 1 below shows a parameter comparison based on the difference in frequency band in the equation.
[0030]
As the range resolution increases, Ls increases.
Ls (30 MHz)> Ls (100 MHz)
(−2La−La / √3) decreases as the frequency band increases as shown in Table 1. Therefore, it can be confirmed that the target estimated length L is corrected so as to be a close value regardless of the frequency band. In this way, the accuracy of target length estimation can be improved even in a frequency band that is not sufficient.
[0031]
[Table 1]
Frequency band Range resolution -2La-La / $ 3
100MHz 1.5m-3.9m
30MHz 5m -12.9m
[0032]
The target length a when viewed from the 0 ° direction, the target length b when viewed from the 30 ° direction, and the target length c when viewed from the 90 ° direction in FIG. The apparent target length changes. Therefore, based on the tracking information from the radar signal processing unit 5, the expected angle from the radio wave emission direction of the radar is calculated, and correction is performed, for example, as shown in Expression (3).
[0033]
Lo = L / F (θ) (3) Expression Lo: Estimated target length L in consideration of expected angle L: Estimated target length F in consideration of expected angle F (θ): Function of expected angle θ, for example, F (0 °) = 1
F (30 °) = 2
F (90 °) = 5
[0034]
The RCS data fluctuates depending on the target posture. Therefore, the averaging unit 73 calculates the RCS from the received power for each hit and obtains the RCS from the 50% point as a histogram to minimize the influence of the fluctuation. The classification unit 74 performs target classification based on information from the target length estimation unit 71 and the pattern recognition unit 72.
[0035]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the target classification apparatus and radar apparatus which concern on this invention, by inputting the range profile which shows the target range versus RCS characteristic, and the tracking information of a target, and outputting the kind of target, the classification processing which is accurate also in a narrow frequency band. Can be realized. In addition, by estimating the target length using a plurality of formulas corresponding to the range profile shape, the accuracy of the target classification can be improved even when sufficient range resolution cannot be obtained.
[0036]
In addition, an RPC is calculated from the received power for each hit, an average value of these RCSs is obtained, and an average processing unit that corrects the range profile is further provided, so that the fluctuation of the range profile due to the fluctuation of the target posture can be corrected. Further, by changing in accordance with the correction term included in the total formula to the size of the resolution, it is possible to further improve the accuracy of the target classification, even if not sufficient range resolution is obtained.
[0037]
In other words, the classification accuracy can be increased even in a feasible 30 MHz frequency band. The reason is that an averaging unit that reduces the variation of the range profile due to the variation of the target posture is provided, a target length estimating unit that calculates the target length from a stable range profile, and a pattern recognition unit that performs pattern recognition are provided. This is because a target categorizing device for comprehensively categorizing targets based on the means and the wake information is provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of a radar device according to the present invention.
FIG. 2 is a block diagram illustrating a target classification device used in the radar device of FIG. 1;
FIG. 3 is a graph showing a range profile, wherein FIG. 3 [1] is for a missile, and FIG. 3 [2] is for an aircraft.
FIG. 4 is an explanatory diagram showing a change in a target length according to a radar prospective angle.
FIG. 5 is a block diagram showing a conventional radar device.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 antenna 2 switching unit 3 radar receiving unit 4 wideband receiving unit 5 radar signal processing unit 6 wideband signal processing unit 7 target classification device 8 circulator 9 radar transmission unit 10 wideband modulation signal generating unit 12 radar device 71 target length estimating unit 72 pattern recognition Unit 73 Average processing unit 74 Classification unit a Target length b when viewed from 0 ° direction Target length c when viewed from 30 ° direction c Target length when viewed from 90 ° direction

Claims (7)

What is claimed is: 1. A target classifying device which inputs a range profile indicating a target range versus RCS (radar reflection cross-sectional area) characteristics and tracking information of the target, and outputs a type of the target.
A target length estimating unit for estimating a target length from the range profile; a pattern recognizing unit for recognizing the pattern of the range profile in consideration of the tracking information; a target length estimated by the target length estimating unit and the pattern recognition A classification unit that performs a classification process based on the range profile pattern-recognized by the unit ,
The target length estimating unit obtains a range profile length Ls equal to or more than a threshold level if the range profile has one peak, and a first peak range Xa and a last peak range Xb if the range profile has a plurality of peaks. Is calculated, and a target length L is calculated using a predetermined calculation formula.
Target categorization device. The predetermined formula is the following formula (1) or (2).
L = Ls−2La−La / √3 + C1 (1)
L = Xb−Xa + La / √3 + C2 (2)
(However, La is a range resolution, and C1 and C2 are correction terms.)
The target classification device according to claim 1. The target length estimating unit calculates an expected angle θ from the radar radio wave emission direction based on the tracking information, and corrects the target length L by the following equation (3):
  Lo = L / F (θ) Equation (3)
    (However, Lo is the target length in consideration of the prospective angle, and F (θ) is a function of the prospective angle θ.)
  The target classification device according to claim 1 or 2. RCS is calculated from the received power for each hit, an average value of these RCSs is obtained, and an average processing unit for correcting the range profile is further provided.
The target classification device according to claim 1. The target length estimating unit changes the correction term included in the calculation formula according to the magnitude of the resolution,
The target classification device according to claim 1. A radar device comprising the target classification device according to claim 1 . An antenna for transmitting and receiving radar radio waves, a wideband modulation signal generating section for generating a signal modulated in a wide band to improve the resolution in the range direction, and a radar transmitting section for amplifying and frequency converting the wideband modulated signal to generate a radar transmission signal A circulator for switching transmission / reception signals, a switching unit for switching between a wideband reception system and a narrowband reception system, a radar reception unit for performing reception processing in the narrowband reception system, and a signal in the narrowband reception system. A radar signal processing unit for performing processing, a wideband receiving unit for receiving a reflected signal from a target in the wideband receiving system, a wideband signal processing unit for high-pulse compressing a signal received in a wideband in the wideband receiving system, claim 1 for target classification process based on a range profile resolution in the range direction is improved by a pulse compression and tracking information A target classification apparatus according to any one of Itaru 5,
Radar device equipped with

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