JP2009019952A - Moving target detector - Google Patents

Moving target detector Download PDF

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JP2009019952A
JP2009019952A JP2007181866A JP2007181866A JP2009019952A JP 2009019952 A JP2009019952 A JP 2009019952A JP 2007181866 A JP2007181866 A JP 2007181866A JP 2007181866 A JP2007181866 A JP 2007181866A JP 2009019952 A JP2009019952 A JP 2009019952A
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complex signal
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moving target
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JP5247077B2 (en
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Masafumi Iwamoto
雅史 岩本
Masao Tsuji
雅生 辻
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Mitsubishi Electric Corp
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<P>PROBLEM TO BE SOLVED: To provide a moving target detector for maximizing a detection probability of a moving target even if a DPCA (Displaced-Phase-Center-Antenna) condition is not satisfied. <P>SOLUTION: The moving target detector amplifies the first and second pulses continuously transmitted and received at a pulse repetition interval, reproduces radar images from the predetermined number of the first and second complex signals obtained by a synchronous detection, creates a conjugate complex signal from the first complex signal for composing one radar image, creates a complex signal of a product to be detected by multiplying the conjugate complex signal by the second complex signal for composing the other radar image, and calculates a possibility density of the complex signal of the product by using a phase deviation obtained from a speed of a radar platform relative to the ground and considering an offset from the DPCA condition of a transmitting/receiving antenna. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

この発明は、移動しているプラットフォームに搭載される移動目標検出装置に関するものである。   The present invention relates to a moving target detection device mounted on a moving platform.

レーダでは一般に指向性を有するアンテナから電磁波を放射し、目標からの散乱波を観測する。この時、目標からの散乱波と同時に地表面からの強大な不要反射（クラッタ）が観測されるので、反射の小さな目標を検出することは容易でない。そこで、例えば移動目標を観測する場合には、ドップラー効果を利用してクラッタを抑圧し目標信号を検出する方法が用いられる。   Radar generally emits electromagnetic waves from a directional antenna and observes scattered waves from a target. At this time, since a large unnecessary reflection (clutter) from the ground surface is observed simultaneously with the scattered wave from the target, it is not easy to detect a target having a small reflection. Thus, for example, when a moving target is observed, a method of detecting a target signal by suppressing clutter using the Doppler effect is used.

ところが、レーダプラットフォームが移動する場合には、アンテナビームの角度拡がりに応じてクラッタのドップラー周波数が拡がるので、低速で移動する目標の信号を弁別することが困難な場合が発生する。そこで、アンテナ開口をレーダプラットフォームの移動方向に分割して、継続する２パルスの間において等価的にアンテナが静止した状況を作り出し、クラッタを抑圧する技術が考案されている。この技術では、クラッタは正の実数として観測され、移動する目標は位相角をもつ複素数として観測されることが期待される。   However, when the radar platform moves, the Doppler frequency of the clutter increases according to the angular spread of the antenna beam, and it may be difficult to discriminate a target signal that moves at low speed. Therefore, a technique has been devised in which the antenna aperture is divided in the moving direction of the radar platform to create a situation where the antenna is equivalently stationary between two continuous pulses, and to suppress clutter. In this technique, clutter is observed as a positive real number, and a moving target is expected to be observed as a complex number having a phase angle.

しかし、例えば樹木は風によって揺らぎ、または受信機の熱雑音によって信号の振幅と位相は変動する。このため、クラッタであっても実数として観測されず、実軸のまわりに分布した複素数として観測される。そこで、あるしきい値を設定し、複素信号平面上でクラッタと移動する目標とを区別する（例えば、非特許文献１参照）。   However, for example, trees fluctuate due to wind, or the amplitude and phase of the signal fluctuate due to receiver thermal noise. For this reason, even a clutter is not observed as a real number, but is observed as a complex number distributed around the real axis. Therefore, a certain threshold value is set to distinguish between the clutter and the moving target on the complex signal plane (see, for example, Non-Patent Document 1).

すなわち、複素信号の振幅をη、位相角をψ、近傍平均をとる画素の数であるプリサム数をｎ、２枚のレーダ画像のコヒーレントをρ、ガンマ関数をΓ、第２種の変形ベッセル関数をＫとして、複素信号の確率密度ｐ（η，ψ）を、式（１）で求める。それから、複素信号の確率密度ｐ（η，ψ）が等しくなるように振幅ηと位相角ψを選び、等確率密度線を求める。そして、与えられた誤警報確率Ｐｆａの下で検出確率を最大化するしきい値Ｐｔｈを式（２）で求める。最後に各複素信号について式（１）に従って確率密度ｐ（η，ψ）を求め、求めた確率密度ｐ（η，ψ）がしきい値Ｐｔｈ以下であれば移動目標であると判断する。 That is, the amplitude of the complex signal is η, the phase angle is ψ, the number of presums is the number of pixels taking the neighborhood average, the coherent of the two radar images is ρ, the gamma function is Γ, and the second modified Bessel function Is K, and the probability density p (η, ψ) of the complex signal is obtained by the equation (1). Then, the amplitude η and the phase angle ψ are selected so that the probability densities p (η, ψ) of the complex signals are equal to obtain an equal probability density line. Then, a threshold value P th that maximizes the detection probability under the given false alarm probability P fa is obtained by the equation (2). Finally, the probability density p (η, ψ) is obtained for each complex signal according to the equation (1). If the obtained probability density p (η, ψ) is equal to or less than the threshold value Pth , it is determined that the target is a moving target.

Figure 2009019952
Figure 2009019952

Ｃ．Ｈ．Ｇｉｅｒｕｌｌ著、「Ｓｔａｔｉｃａｌ Ａｎａｌｙｓｉｓ ｏｆ Ｍｕｌｔｉｌｏｏｋ ＳＡＲ Ｉｎｔｅｒｆｅｒｏｇｒａｍｓ ｆｏｒ ＣＦＡＲ Ｄｅｔｅｃｔｉｏｎ ｏｆ Ｇｒｏｕｎｄ Ｍｏｖｉｎｇ Ｔａｒｇｅｔｓ」、ＩＥＥＥ ＴＲＡＮＳＡＣＴＩＯＮ ＯＮ ＧＥＯＳＣＩＥＮＣＥ ＡＮＤ ＲＥＭＯＴＥ ＳＥＮＳＩＮＧ、２００４年４月、ＶＯＬ．４２、ＮＯ．４、ｐｐ．６９１−７０１C. H. By Gierull, “Statistic Analysis of Multilok SAR Interferograms for CFAR Detection of Ground Moving Moving Targets”, IEEE TRANSACTION ON GEOSCIENCE 42, NO. 4, pp. 691-701

ところで、従来のレーダ装置は、継続して送信された２つのパルスのうちの先に送信された第１のパルスにおける送受信の電気的位相中心と、次に送信された第２のパルスにおける送受信の電気的位相中心が一致することを前提としている。そして、２つの電気的位相中心が一致するためのＤｉｓｐｌａｃｅｄ−Ｐｈａｓｅ−Ｃｅｎｔｅｒ−Ａｎｔｅｎｎａ（以下、「ＤＰＣＡ」と称す）条件は、アンテナの開口長Ｄ、パルス繰り返し間隔Ｔｐ、レーダプラットフォームの対地速度ｖの間で条件式（３）を満足することである。 By the way, the conventional radar apparatus has an electric phase center of transmission / reception in the first pulse transmitted first among two pulses transmitted continuously and transmission / reception in the second pulse transmitted next. It is assumed that the electrical phase centers coincide. Then, the Displaced-Phase-Center-Antenna (hereinafter referred to as “DPCA”) conditions for matching the two electrical phase centers are the antenna opening length D, the pulse repetition interval T p , and the radar platform ground velocity v. Is satisfied with conditional expression (3).

Figure 2009019952
Figure 2009019952

すなわち、ＤＰＣＡ条件を満足するためには、レーダプラットフォームの対地速度ｖに応じてパルス繰り返し間隔Ｔｐを調整する必要があり、実用においてはこのＤＰＣＡ条件を満足できない場合が発生する。そして、ＤＰＣＡ条件を満足できない場合、クラッタの分布は等確率密度線からはずれているので、与えられた誤警報確率Ｐｆａの下で移動目標の検出確率を最大化することができないという問題がある。 In other words, in order to satisfy the DPCA condition, it is necessary to adjust the pulse repetition interval T p according to the ground speed v of the radar platform, and this DPCA condition may not be satisfied in practice. If the DPCA condition cannot be satisfied, the clutter distribution deviates from the equiprobability density line, and thus there is a problem that the detection probability of the moving target cannot be maximized under the given false alarm probability P fa. .

この発明の目的は、ＤＰＣＡ条件を満足しない場合でも移動目標の検出確率を最大化できる移動目標検出装置を提供することである。   An object of the present invention is to provide a moving target detection apparatus capable of maximizing the detection probability of a moving target even when the DPCA condition is not satisfied.

この発明に係る移動目標検出装置は、プラットフォームの移動方向に分割された２つの開口を持ち且つパルス繰り返し間隔でパルスが発信されるアンテナ、一方の上記開口で受信されたパルスが変換された第１の複素信号をパルス繰り返し間隔分遅延する遅延手段、上記遅延された所定数の第１の複素信号から第１のレーダ画像を再生する第１の画像再生手段、および上記一方の開口で受信されたパルスから上記パルス繰り返し間隔分遅れて発信され且つ他方の上記開口で受信されたパルスが変換された所定数の第２の複素信号から第２のレーダ画像を再生する第２の画像再生手段を備える移動目標検出装置において、上記第２のレーダ画像を構成する第２の複素信号の複素共役を求める複素共役手段と、上記第１のレーダ画像を構成する第１の複素信号に上記第２のレーダ画像の複素共役の信号を乗算して積の複素信号を求める乗算手段と、上記プラットフォームの対地速度を求める手段と、上記パルス繰り返し間隔の間に上記アンテナが移動した距離と上記アンテナの開口長の４分の１との差を算出する手段と、上記アンテナのアンテナパターンを記憶する手段と、上記差およびコヒーレンスに基づいてしきい値を算出する手段と、上記算出したしきい値と上記乗算手段の積の複素信号の振幅と位相とに基づいて移動目標からの信号を検出する手段と、を備えた。   The moving target detection apparatus according to the present invention includes an antenna having two openings divided in the moving direction of the platform and transmitting a pulse at a pulse repetition interval, and a first pulse converted from one of the openings. Received by the delay means for delaying the complex signal by the pulse repetition interval, the first image reproduction means for reproducing the first radar image from the predetermined number of delayed first complex signals, and the one aperture A second image reproducing unit that reproduces a second radar image from a predetermined number of second complex signals that are transmitted with a delay of the pulse repetition interval and received from the other aperture; In the moving target detection apparatus, complex conjugate means for obtaining a complex conjugate of the second complex signal that constitutes the second radar image, and a first that constitutes the first radar image. The signal obtained by multiplying the complex signal of the second radar image by the complex conjugate signal of the second radar image to obtain the complex signal of the product, the means for obtaining the ground speed of the platform, and the antenna moving between the pulse repetition intervals Means for calculating the difference between the measured distance and a quarter of the antenna aperture length; means for storing the antenna pattern of the antenna; means for calculating a threshold based on the difference and coherence; Means for detecting a signal from the moving target based on the calculated threshold value and the amplitude and phase of the complex signal of the product of the multiplication means.

この発明に係る移動目標検出装置の効果は、パルス繰り返し間隔で連続して送受信される第１のパルスと第２のパルスを増幅し同期検波して得られる所定数の第１の複素信号と第２の複素信号それぞれからレーダ画像を再生し、一方のレーダ画像を構成する第１の複素信号から複素共役な複素信号を生成し、この複素共役な複素信号と他方のレーダ画像を構成する第２の複素信号とを乗算して検出対象の複素信号を生成し、一方、レーダプラットフォームの対地速度から求まる位相偏差を用いて送受信アンテナのＤＰＣＡ条件からのずれを考慮した複素信号の確率密度からクラッタと移動目標とを判別するしきい値を求めるので、等確率密度線がクラッタの分布とよく一致しており、与えられた誤警報確率の下で移動目標の検出確率を最大とすることができることである。   The effect of the moving target detection apparatus according to the present invention is that the predetermined number of first complex signals obtained by amplifying and synchronously detecting the first pulse and the second pulse transmitted and received continuously at the pulse repetition interval and the first pulse A radar image is reproduced from each of the two complex signals, a complex conjugate complex signal is generated from the first complex signal constituting one radar image, and the second complex image and the second radar image constituting the other radar image are generated. And a complex signal to be detected to generate a complex signal to be detected. On the other hand, the phase deviation obtained from the ground speed of the radar platform is used to determine the clutter from the probability density of the complex signal considering the deviation from the DPCA condition of the transmitting / receiving antenna. Since the threshold value for discriminating the moving target is obtained, the equiprobability density line agrees well with the clutter distribution, and the detection probability of the moving target is maximized under the given false alarm probability. It is that it is Rukoto.

実施の形態１．   Embodiment 1 FIG.

図１は、この発明に係る実施の形態１による移動目標検出装置を用いて観測するときのジオメトリを表す。
この発明に係る実施の形態１による移動目標検出装置は、例えば航空機、艦船、衛星などのようなレーダプラットフォーム３０に搭載され、移動している移動目標３２を観測する。なお、以下の説明では移動目標検出装置の送受信アンテナ１のアンテナ開口面をレーダプラットフォーム３０の進行方向に平行になるように設定し、送受信アンテナ１のビームをアンテナ開口面に対して垂直になるように設定し、ビームのフットプリント３１を図１に示すように設定して説明する。また、２次元平面内を仮定して動作を説明するが、これらの仮定を満足しない場合であっても、容易に拡張して考えることが可能である。 FIG. 1 shows a geometry when observation is performed using the moving target detection apparatus according to Embodiment 1 of the present invention.
The moving target detection apparatus according to the first embodiment of the present invention is mounted on a radar platform 30 such as an aircraft, a ship, a satellite, etc., and observes a moving moving target 32. In the following description, the antenna opening surface of the transmitting / receiving antenna 1 of the moving target detection apparatus is set to be parallel to the traveling direction of the radar platform 30 so that the beam of the transmitting / receiving antenna 1 is perpendicular to the antenna opening surface. The beam footprint 31 is set as shown in FIG. Although the operation will be described assuming a two-dimensional plane, even if these assumptions are not satisfied, it can be easily expanded and considered.

図２は、この発明に係る実施の形態１による移動目標検出装置の構成図である。
この発明に係る実施の形態１による移動目標検出装置は、送受信アンテナ１の２つの第１のアンテナ２および第２のアンテナ３、送信機８、第１の送受切換器９ａ、第２の送受切換器９ｂ、第１の受信機１０ａ、第２の受信機１０ｂ、第１の受信機１０ａからの第１の複素信号を遅延させる遅延手段１１、遅延手段１１で遅延された第１の複素信号を記憶する第１の記憶手段３３ａ、および、第２の受信機１０ｂからの第２の複素信号を記憶する第２の記憶手段３３ｂを備える。 FIG. 2 is a block diagram of the moving target detection apparatus according to Embodiment 1 of the present invention.
The moving target detection apparatus according to Embodiment 1 of the present invention includes two first antennas 2 and second antennas 3 of a transmission / reception antenna 1, a transmitter 8, a first transmission / reception switch 9a, and a second transmission / reception switching. 9b, first receiver 10a, second receiver 10b, delay means 11 for delaying the first complex signal from the first receiver 10a, and the first complex signal delayed by the delay means 11. First storage means 33a for storing and second storage means 33b for storing the second complex signal from the second receiver 10b are provided.

送受信アンテナ１の開口長をＤとすると、第１のアンテナ２と第２のアンテナ３の開口長はそれぞれＤ／２である。
送信機８は、パルス繰り返し間隔Ｔｐ’毎に高周波パルスを発生し、第１の送受切換器９ａと第２の送受切換器９ｂの両方に送信する。
第１の送受切換器９ａと第２の送受切換器９ｂは、それぞれ送信機８からの高周波パルスを第１のアンテナ２と第２のアンテナ３に送信するとともに、第１のアンテナ２と第２のアンテナ３が受信したパルスをそれぞれ第１の受信機１０ａと第２の受信機１０ｂに送信する。なお、第１のアンテナ２で受信したパルスを第１のパルス、第２のアンテナ３で受信したパルスを第２のパルスと称す。
第１のアンテナ２と第２のアンテナ３とから同じ高周波パルスが同時に空中に放射され、送受信アンテナ１の電気的位相中心位置から送信したことになる。また、受信した第１のパルスと第２のパルスは、それぞれ第１のアンテナ２と第２のアンテナ３の電気的位相中心位置で受信したことになる。 When the opening length of the transmitting / receiving antenna 1 is D, the opening lengths of the first antenna 2 and the second antenna 3 are D / 2, respectively.
The transmitter 8 generates a high-frequency pulse at every pulse repetition interval T p ′ and transmits it to both the first transmission / reception switch 9a and the second transmission / reception switch 9b.
The first transmission / reception switch 9a and the second transmission / reception switch 9b transmit high frequency pulses from the transmitter 8 to the first antenna 2 and the second antenna 3, respectively, and the first antenna 2 and the second transmission switch 9b. The pulses received by the antenna 3 are transmitted to the first receiver 10a and the second receiver 10b, respectively. The pulse received by the first antenna 2 is called a first pulse, and the pulse received by the second antenna 3 is called a second pulse.
The same high-frequency pulse is simultaneously radiated from the first antenna 2 and the second antenna 3 into the air and transmitted from the electrical phase center position of the transmission / reception antenna 1. Also, the received first pulse and second pulse are received at the electrical phase center positions of the first antenna 2 and the second antenna 3, respectively.

第１の受信機１０ａは、第１のパルスを増幅し、同期検波して得られた第１の複素信号を遅延手段１１に送信する。
第２の受信機１０ｂは、第２のパルスを増幅し、同期検波して得られた第２の複素信号を第２の記憶手段３３ｂに送信する。
遅延手段１１は、第１の複素信号を１パルス繰り返し間隔分時間遅延して第１の記憶手段３３ａに送信する。 The first receiver 10 a amplifies the first pulse and transmits the first complex signal obtained by synchronous detection to the delay means 11.
The second receiver 10b amplifies the second pulse and transmits the second complex signal obtained by synchronous detection to the second storage means 33b.
The delay means 11 transmits the first complex signal to the first storage means 33a after being delayed by one pulse repetition interval.

また、この発明に係る実施の形態１による移動目標検出装置は、第１の画像再生手段１２ａ、第２の画像再生手段１２ｂ、第２の複素信号の複素共役を求める複素共役手段１３、第１の複素信号と第２の複素信号の複素共役の信号とを乗算する乗算手段１４、および、近傍の画素の複素信号をプリサムするプリサム手段２７を備える。   The moving target detection apparatus according to the first embodiment of the present invention includes a first image reproduction unit 12a, a second image reproduction unit 12b, a complex conjugate unit 13 for obtaining a complex conjugate of a second complex signal, The multiplication means 14 for multiplying the complex signal of the second complex signal and the complex conjugate signal of the second complex signal, and the presum means 27 for presuming the complex signals of neighboring pixels.

第１の画像再生手段１２ａは、第１の記憶手段３３ａに所定数のパルスから得られた第１の複素信号が蓄積される度に第１の記憶手段３３ａから読み出して第１のレーダ画像として再生する。なお、その原理・手順は合成開口レーダの画像再生処理としてよく知られるものである。
第２の画像再生手段１２ｂは、第２の記憶手段３３ｂに所定数のパルスから得られた第２の複素信号が蓄積される度に第２の記憶手段３３ｂから読み出して第２のレーダ画像として再生する。 The first image reproduction means 12a reads out from the first storage means 33a each time a first complex signal obtained from a predetermined number of pulses is accumulated in the first storage means 33a, as a first radar image. Reproduce. The principle and procedure are well known as image reproduction processing of a synthetic aperture radar.
The second image reproduction means 12b reads out from the second storage means 33b each time a second complex signal obtained from a predetermined number of pulses is accumulated in the second storage means 33b, as a second radar image. Reproduce.

複素共役手段１３は、第２の画像再生手段１２ｂからの第２のレーダ画像を構成する第２の複素信号に対する複素共役信号を出力する。
乗算手段１４は、第１の画像再生手段１２ａからの第１のレーダ画像を構成する第１の複素信号と複素共役手段１３からの第２のレーダ画像を構成する第２の複素信号に対する複素共役の複素信号とを乗算して積の複素信号を求める。
プリサム手段２７は、近傍の画素での乗算手段１４からの積の複素信号をプリサムして和の複素信号を求め、和の複素信号とプリサム数ｎを出力する。 The complex conjugate means 13 outputs a complex conjugate signal for the second complex signal that constitutes the second radar image from the second image reproduction means 12b.
The multiplying unit 14 is a complex conjugate with respect to the first complex signal constituting the first radar image from the first image reproducing unit 12a and the second complex signal constituting the second radar image from the complex conjugate unit 13. Is multiplied by the complex signal to obtain a product complex signal.
The presum means 27 presums the complex signal of the product from the multiplication means 14 in the neighboring pixels to obtain a sum complex signal, and outputs the sum complex signal and the presum number n.

また、この発明に係る実施の形態１による移動目標検出装置は、対地速度センサ２２、位置ずれ算出手段２１、アンテナパターン記憶手段３５、しきい値算出手段２０、および検出手段３４を備える。   The moving target detection apparatus according to the first embodiment of the present invention includes a ground speed sensor 22, a positional deviation calculation means 21, an antenna pattern storage means 35, a threshold value calculation means 20, and a detection means 34.

対地速度センサ２２は、レーダプラットフォーム３０の対地速度ｖを計測する。
アンテナパターン記憶手段３５は、位相偏差Δφに対するアンテナ利得ｐａ（Δφ）が記憶されている。
位置ずれ算出手段２１は、送受信アンテナ１の開口長Ｄ、パルス繰り返し間隔Ｔｐ’、レーダプラットフォーム３０の対地速度ｖを式（４）に代入して、第１のパルスにおける送受信の電気的位相中心位置と、第２のパルスにおける送受信の電気的位相中心位置との位置ずれΔｘを算出する。 The ground speed sensor 22 measures the ground speed v of the radar platform 30.
The antenna pattern storage means 35 stores the antenna gain p a (Δφ) with respect to the phase deviation Δφ.
The displacement calculation means 21 substitutes the opening length D of the transmission / reception antenna 1, the pulse repetition interval T p ′, and the ground speed v of the radar platform 30 into the equation (4), and transmits and receives the electrical phase center of transmission / reception in the first pulse. A positional deviation Δx between the position and the electrical phase center position of transmission / reception in the second pulse is calculated.

Figure 2009019952
Figure 2009019952

しきい値算出手段２０は、位置ずれΔｘ、速度ベクトルと直交する方位を基準としたアンテナビームの方位角θおよびレーダの送信波長λを式（５）に代入して位相偏差Δφを算出する。また、しきい値算出手段２０は、位相偏差Δφに関するアンテナ利得ｐａ（Δφ）をアンテナパターン記憶手段３５から読み出す。
また、しきい値算出手段２０は、和の複素信号の振幅ηおよび位相角ψ、算出される位相偏差Δφ、プリサム手段２７のプリサムにおいて用いられる近傍平均をとる画素の数であるプリサム数ｎ、予め定められたコヒーレンスρ、読み出したアンテナ利得ｐａ（Δφ）を式（６）に代入して和の複素信号の確率密度ｐ’（η，ψ）を算出する。なお、式（６）のΓはガンマ関数、Ｋは第２種の変形ベッセル関数である。
また、しきい値算出手段２０は、式（６）から求めた和の複素信号の確率密度ｐ’（η，ψ）を用いて、与えられた誤警報確率Ｐｆａの下で検出確率を最大化するしきい値Ｐｔｈを式（７）で求める。 The threshold value calculating means 20 calculates the phase deviation Δφ by substituting the positional deviation Δx, the azimuth angle θ of the antenna beam with respect to the direction orthogonal to the velocity vector, and the transmission wavelength λ of the radar into equation (5). Further, the threshold value calculation means 20 reads out the antenna gain p a (Δφ) related to the phase deviation Δφ from the antenna pattern storage means 35.
Further, the threshold value calculation means 20 includes the amplitude η and the phase angle ψ of the sum complex signal, the calculated phase deviation Δφ, and the presum number n, which is the number of pixels taking the neighborhood average used in the presum of the presum means 27, predetermined coherence [rho, read antenna gain p probability density p of the complex signal of the sum by substituting a the ([Delta] [phi) in equation (6) '(η, ψ ) is calculated. In Equation (6), Γ is a gamma function, and K is a second type modified Bessel function.
Further, the threshold value calculation means 20 uses the probability density p ′ (η, ψ) of the sum complex signal obtained from the equation (6) to maximize the detection probability under the given false alarm probability P fa. The threshold value P th to be converted is obtained by equation (7).

Figure 2009019952
Figure 2009019952

検出手段３４は、各和の複素信号について式（６）に従って確率密度ｐ’（η，ψ）を求め、求めた確率密度ｐ’（η，ψ）がしきい値Ｐｔｈ以下であれば移動目標であると判断する。 The detection means 34 obtains the probability density p ′ (η, ψ) according to the equation (6) for each complex signal, and moves if the obtained probability density p ′ (η, ψ) is less than or equal to the threshold value P th. Judge as a goal.

図３は、この発明に係る実施の形態１による移動目標検出装置での送受信の際の送受信アンテナ１の位置関係を示す図である。
次に、この発明に係る実施の形態１による移動目標検出装置の動作を説明する。
送信機８が発生した高周波パルスは、先のパルスとして第１の送受切換器９ａと第２の送受切換器９ｂを通して第１のアンテナ２および第２のアンテナ３から同時に空中に放射される。すなわち、先のパルスは電気的位相中心位置５ａから送信されたことになる。
先のパルスは移動目標に到達し反射して送受信アンテナ１に戻ってくるが、その間に送受信アンテナ１は電波伝播遅延時間をτ、レーダプラットフォーム３０の対地速度をｖとすると距離ｖ・τだけ移動する。そして、戻ってきた先のパルスを第１のアンテナ２で受信するが、電気的位相中心位置６ａで受信されたことになる。この第１のアンテナ２で受信された先のパルスを第１のパルスと称す。 FIG. 3 is a diagram showing the positional relationship of the transmission / reception antenna 1 during transmission / reception in the moving target detection apparatus according to Embodiment 1 of the present invention.
Next, the operation of the moving target detection apparatus according to the first embodiment of the present invention will be described.
The high-frequency pulse generated by the transmitter 8 is radiated from the first antenna 2 and the second antenna 3 simultaneously into the air through the first transmission / reception switch 9a and the second transmission / reception switch 9b as the previous pulse. That is, the previous pulse is transmitted from the electrical phase center position 5a.
The previous pulse reaches the moving target, is reflected, and returns to the transmitting / receiving antenna 1. Meanwhile, the transmitting / receiving antenna 1 moves by a distance v · τ, where τ is the radio wave propagation delay time and v is the ground speed of the radar platform 30. To do. Then, the previous pulse that has returned is received by the first antenna 2, but is received at the electrical phase center position 6a. The previous pulse received by the first antenna 2 is referred to as a first pulse.

次に、パルス繰り返し間隔Ｔｐを隔てた次の時点で送信機８が発生した高周波パルスは、後のパルスとして第１の送受切換器９ａと第２の送受切換器９ｂを通して第１のアンテナ２および第２のアンテナ３から同時に空中に放射される。このとき、送受信アンテナ１は、先のパルスを送信した位置から距離ｖ・Ｔｐ’だけ移動しており、後のパルスは電気的位相中心位置５ｂから送信されたことになる。
後のパルスは移動目標に到達し反射して送受信アンテナ１に戻ってくるが、その間に送受信アンテナ１は距離ｖ・τだけ移動する。そして、戻ってきた後のパルスを第２のアンテナ３で受信するが、電気的位相中心位置７ｂで受信されたことになる。この第２のアンテナ３で受信された後のパルスを第２のパルスと称す。 Next, the high frequency pulse generated by the transmitter 8 at the next time point separated by the pulse repetition interval Tp is transmitted through the first antenna 2 and the second transmission / reception switch 9b as the subsequent pulses through the first transmission / reception switch 9a and the second transmission / reception switch 9b. It is simultaneously radiated from the second antenna 3 into the air. At this time, the transmitting / receiving antenna 1 has moved by a distance v · T p ′ from the position where the previous pulse is transmitted, and the subsequent pulse is transmitted from the electrical phase center position 5b.
The subsequent pulse reaches the movement target, is reflected, and returns to the transmission / reception antenna 1, while the transmission / reception antenna 1 moves by a distance v · τ. Then, although the pulse after returning is received by the second antenna 3, it is received at the electrical phase center position 7b. The pulse after being received by the second antenna 3 is referred to as a second pulse.

第１のアンテナ２で受信された第１のパルスは、第１の送受切換器９ａを通して第１の受信機１０ａへ送られ、増幅され、同期検波されて第１の複素信号に変換される。この第１の複素信号は、遅延手段１１によって１パルス繰り返し間隔分だけ時間遅延され、第１の記憶手段３３ａに蓄積される。
第２のアンテナ３で受信された第２のパルスは、第２の送受切換器９ｂを通して第２の受信機１０ｂへ送られ、増幅され、同期検波されて第２の複素信号に変換される。この第２の複素信号は、第２の記憶手段３３ｂに蓄積される。 The first pulse received by the first antenna 2 is sent to the first receiver 10a through the first transmission / reception switch 9a, amplified, synchronously detected, and converted into a first complex signal. The first complex signal is delayed by one pulse repetition interval by the delay means 11 and stored in the first storage means 33a.
The second pulse received by the second antenna 3 is sent to the second receiver 10b through the second transmission / reception switch 9b, amplified, synchronously detected, and converted into a second complex signal. This second complex signal is stored in the second storage means 33b.

第１の記憶手段３３ａに蓄積された所定数の第１の複素信号は、第１の画像再生手段１２ａで第１の記憶手段３３ａから読み出され、第１のレーダ画像を構成する第１の複素信号として出力される。
第２の記憶手段３３ｂに蓄積された所定数の第２の複素信号は、第２の画像再生手段１２ｂで第２の記憶手段３３ｂから読み出され、第２のレーダ画像を構成する第２の複素信号として出力される。
第２のレーダ画像を構成する第２の複素信号は、複素共役手段１３で第２のレーダ画像を構成する複素共役信号に変換される。 A predetermined number of first complex signals accumulated in the first storage means 33a are read from the first storage means 33a by the first image reproduction means 12a, and the first radar image constituting the first radar image is formed. Output as a complex signal.
A predetermined number of second complex signals accumulated in the second storage means 33b are read from the second storage means 33b by the second image reproduction means 12b, and a second radar image constituting the second radar image is formed. Output as a complex signal.
The second complex signal constituting the second radar image is converted by the complex conjugate means 13 into a complex conjugate signal constituting the second radar image.

第１のレーダ画像を構成する第１の複素信号と第２のレーダ画像を構成する複素共役信号とは、乗算手段１４で乗算されて第３のレーダ画像を構成する積の複素信号に変換される。
第３のレーダ画像を構成する積の複素信号は、プリサム手段２７でプリサムされて第４のレーダ画像を構成する和の複素信号に変換される。 The first complex signal constituting the first radar image and the complex conjugate signal constituting the second radar image are multiplied by the multiplication means 14 and converted into a complex signal of the product constituting the third radar image. The
The complex signal of the product constituting the third radar image is presumed by the presum means 27 and converted into the sum complex signal constituting the fourth radar image.

一方、レーダプラットフォーム３０の対地速度ｖは、対地速度センサ２２で計測され、予め定まった送受信アンテナ１の開口長Ｄおよびパルス繰り返し間隔Ｔｐと計測されたレーダプラットフォーム３０の対地速度ｖを式（４）に代入して位置ずれΔｘを算出する。
次に、算出した位置ずれΔｘ、速度ベクトルと直交する方位を基準としたアンテナビームの方位角θおよびレーダの送信波長λを式（５）に代入して位相偏差Δφを算出する。 On the other hand, ground speed v of the radar platform 30 is measured by the ground speed sensor 22, previously stated the transmitting and receiving antenna 1 aperture length D and the pulse repetition interval T p and the measured radar platform 30 of the ground speed v Equation (4 ) To calculate the positional deviation Δx.
Next, the phase deviation Δφ is calculated by substituting the calculated positional deviation Δx, the azimuth angle θ of the antenna beam with reference to the azimuth perpendicular to the velocity vector, and the transmission wavelength λ of the radar into equation (5).

次に、第４のレーダ画像を構成する和の複素信号、算出した位相偏差Δφを用いて和の複素信号の確率密度ｐ’（η，ψ）を式（６）に従って算出する。
次に、式（６）で算出した和の複素信号の確率密度ｐ’（η，ψ）を用いて、与えられた誤警報確率Ｐｆａの下で検出確率を最大化するしきい値Ｐｔｈを式（７）で求める。
最後に、各和の複素信号について式（６）に従って求めた確率密度ｐ’（η，ψ）がしきい値Ｐｔｈ以下であれば移動目標であると判断する。 Next, the probability density p ′ (η, ψ) of the sum complex signal is calculated according to the equation (6) using the sum complex signal constituting the fourth radar image and the calculated phase deviation Δφ.
Next, the threshold P th that maximizes the detection probability under a given false alarm probability P fa using the probability density p ′ (η, ψ) of the sum complex signal calculated by the equation (6). Is obtained by equation (7).
Finally, if the probability density p ′ (η, ψ) obtained according to the equation (6) for each complex signal is equal to or less than the threshold value Pth , it is determined that the target is a moving target.

次に、この発明に係る実施の形態１による移動目標検出装置を用いた観測の結果について説明する。図４は、移動目標検出装置がＤＰＣＡ条件を満たしていないときに観測するクラッタを計算機により模擬し複素信号平面上に図示した図である。
図４（ａ）には、ＤＰＣＡ条件を満たしていないときに式（６）に従って算出したクラッタの確率密度ｐ’（η，ψ）と、クラッタの等確率密度線とが複素信号平面上に図示されている。この図４（ａ）に図示された点１８の座標が各クラッタの振幅と位相を表し、線１９は等確率密度線である。
一方、図４（ｂ）には、比較のために、ＤＰＣＡ条件を満たしていないときに式（１）に従って算出したクラッタの確率密度ｐ（η，ψ）と、クラッタの等確率密度線とが複素信号平面上に図示されている。 Next, the results of observation using the moving target detection apparatus according to Embodiment 1 of the present invention will be described. FIG. 4 is a diagram illustrating a clutter observed when the moving target detection device does not satisfy the DPCA condition by a computer and illustrated on a complex signal plane.
In FIG. 4A, the probability density p ′ (η, ψ) of the clutter calculated according to the equation (6) when the DPCA condition is not satisfied and the equal probability density line of the clutter are illustrated on the complex signal plane. Has been. The coordinates of the point 18 shown in FIG. 4A represent the amplitude and phase of each clutter, and the line 19 is an equiprobability density line.
On the other hand, in FIG. 4B, for comparison, the probability density p (η, ψ) of the clutter calculated according to the equation (1) when the DPCA condition is not satisfied and the equal probability density line of the clutter are shown. It is shown on the complex signal plane.

図４（ｂ）から分かるように、クラッタを示す点１８の分布は等確率密度線１９からはずれており、式（１）を用いて算出した確率密度ｐ（η，ψ）では、与えられた誤警報確率Ｐｆａの下で移動目標の検出確率を最大とすることができない。
一方、図４（ａ）から分かるように、クラッタを示す点１８の分布は等確率密度線１９とよく一致しており、例えＤＰＣＡ条件を満足しない場合においても、与えられた誤警報確率Ｐｆａの下で移動目標の検出確率を最大とすることができる。 As can be seen from FIG. 4B, the distribution of the points 18 indicating the clutter deviates from the equiprobability density line 19 and is given by the probability density p (η, ψ) calculated using the equation (1). The detection probability of the moving target cannot be maximized under the false alarm probability Pfa .
On the other hand, as can be seen from FIG. 4A, the distribution of the points 18 indicating the clutter is in good agreement with the equal probability density line 19, and even if the DPCA condition is not satisfied, the given false alarm probability P fa The detection probability of the moving target can be maximized.

この発明に係る実施の形態１による移動目標検出装置は、パルス繰り返し間隔で連続して送受信される第１のパルスと第２のパルスを増幅し同期検波して得られる所定数の第１の複素信号と第２の複素信号それぞれからレーダ画像を再生し、一方のレーダ画像を構成する第１の複素信号から複素共役な複素信号を生成し、この複素共役な複素信号と他方のレーダ画像を構成する第２の複素信号とを乗算して検出対象の積の複素信号を生成し、一方、レーダプラットフォームの対地速度ｖから求まる位相偏差Δφを用いて送受信アンテナ１のＤＰＣＡ条件からのずれを考慮して積の複素信号の確率密度を算出するので、等確率密度線がクラッタの分布とよく一致しており、与えられた誤警報確率Ｐｆａの下で移動目標の検出確率を最大とすることができる。 The moving target detecting apparatus according to the first embodiment of the present invention a predetermined number of first complex obtained by amplifying and synchronously detecting the first pulse and the second pulse that are continuously transmitted and received at a pulse repetition interval. A radar image is reproduced from each of the signal and the second complex signal, a complex conjugate complex signal is generated from the first complex signal constituting one radar image, and the complex conjugate complex signal and the other radar image are constructed. The second complex signal is multiplied to generate a complex signal of the product to be detected. On the other hand, the phase deviation Δφ obtained from the ground speed v of the radar platform is used to consider the deviation of the transmission / reception antenna 1 from the DPCA condition. since calculating the probability density of the complex signal product Te has equal probability density lines in good agreement with the distribution of the clutter, the maximum probability of detecting the movement under a given false alarm probability P fa goals that you Can.

実施の形態２．
図５は、この発明に係る実施の形態２による移動目標検出装置の構成を示す図である。
この発明に係る実施の形態２による移動目標検出装置は、図５に示すように、この発明に係る実施の形態１による移動目標検出装置のしきい値算出手段２０の代わりにしきい値読み出し手段２３、しきい値テーブル算出手段２４およびしきい値記憶手段２５を備えたことが異なり、それ以外は同様であるので、同様な部分に同じ符号を付記し説明は省略する。 Embodiment 2. FIG.
FIG. 5 is a diagram showing the configuration of a moving target detection apparatus according to Embodiment 2 of the present invention.
As shown in FIG. 5, the moving target detecting apparatus according to the second embodiment of the present invention is a threshold reading means 23 instead of the threshold calculating means 20 of the moving target detecting apparatus according to the first embodiment of the present invention. The difference is that the threshold value table calculating means 24 and the threshold value storing means 25 are provided, and the others are the same, and thus the same parts are denoted by the same reference numerals and the description thereof is omitted.

しきい値テーブル算出手段２４は、想定されるプリサム数ｎおよび位置ずれΔｘに基づいて予めしきい値Ｐｔｈを計算し、得たしきい値をしきい値記憶手段２５に格納されているしきい値テーブルに記憶する。
しきい値読み出し手段２３は、プリサム手段２７のプリサムで用いたプリサム数ｎおよび位置ずれ算出手段２１からの位置ずれΔｘに基づいてしきい値テーブルから対応するしきい値Ｐｔｈを読み出し、検出手段３４へ出力する。 The threshold value table calculating means 24 calculates the threshold value P th in advance based on the presumed number n and the positional deviation Δx, and the obtained threshold value is stored in the threshold value storing means 25. Store in the threshold table.
The threshold value reading means 23 reads the corresponding threshold value P th from the threshold value table based on the number of presums n used in the presum of the presum means 27 and the positional deviation Δx from the positional deviation calculation means 21, and the detecting means 34.

この発明に係る実施の形態２による移動目標検出装置は、想定されるプリサム数ｎおよび位置ずれΔｘ毎に予めしきい値を算出し、算出したしきい値をしきい値記憶手段２５に格納されているしきい値テーブルに記憶しておき、実際のプリサム手段２７で用いたプリサム数ｎと実際の位置ずれΔｘとによりしきい値テーブルを検索して対応するしきい値Ｐｔｈを読み出し検出手段３４の判断に使用するので、リアルタイムにしきい値を計算する場合に比べて計算機の負荷が減少する。 The moving target detection apparatus according to the second embodiment of the present invention calculates a threshold value in advance for each presum number n and positional deviation Δx, and the calculated threshold value is stored in the threshold value storage means 25. The threshold value table is stored in the threshold value table, the threshold value table is searched based on the number n of the presums used in the actual presum means 27 and the actual positional deviation Δx, and the corresponding threshold value P th is read and detected. Therefore, the load on the computer is reduced as compared with the case where the threshold value is calculated in real time.

実施の形態３．
図６は、この発明に係る実施の形態３による移動目標検出装置の構成を示す図である。
この発明に係る実施の形態３による移動目標検出装置は、図６に示すように、この発明に係る実施の形態１による移動目標検出装置にコヒーレンス推定手段２６を追加したことが異なり、それ以外は同様であるので、同様な部分に同じ符号を付記し説明は省略する。
この発明に係る実施の形態３によるコヒーレンス推定手段２６は、第１の画像再生手段１２ａから出力される第１のレーダ画像の第１の複素信号と第２の画像再生手段１２ｂから出力される第２のレーダ画像の第２の複素信号とのコヒーレンスρを推定する。
しきい値算出手段２０は、和の複素信号の振幅ηおよび位相角ψ、算出される位相偏差Δφ、プリサム数ｎ、第１のレーダ画像と第２のレーダ画像とのコヒーレンスρ、読み出したアンテナ利得ｐａ（Δφ）を式（６）に代入して和の複素信号の確率密度ｐ’（η，ψ）を算出するが、コヒーレンスρはコヒーレンス推定手段２６が推定した値を代入する。 Embodiment 3 FIG.
FIG. 6 is a diagram showing the configuration of the moving target detection apparatus according to Embodiment 3 of the present invention.
The moving target detection apparatus according to Embodiment 3 of the present invention differs from the moving target detection apparatus according to Embodiment 1 of the present invention in that coherence estimation means 26 is added, as shown in FIG. Since it is the same, the same code | symbol is attached to the same part and description is abbreviate | omitted.
The coherence estimation unit 26 according to the third embodiment of the present invention includes the first complex signal of the first radar image output from the first image reproduction unit 12a and the first complex signal output from the second image reproduction unit 12b. Estimate the coherence ρ of the second radar image with the second complex signal.
The threshold calculation means 20 includes the amplitude η and the phase angle ψ of the sum complex signal, the calculated phase deviation Δφ, the presum number n, the coherence ρ between the first radar image and the second radar image, and the read antenna. gain p a ([Delta] [phi) equation (6) to assign to the probability density p '(eta, [psi) of the complex signal sum will be calculated, the coherence ρ assigns a value to the coherence estimator 26 is estimated.

次に、この発明に係る実施の形態３による移動目標検出装置の動作について説明する。
なお、実施の形態１による移動目標検出装置の動作とコヒーレンスρを推定する動作が加わったことが異なるので、この加わった動作だけについて説明する。
第１のレーダ画像を構成する第１の複素信号と第２のレーダ画像を構成する第２の複素信号とは、コヒーレンス推定手段２６で第１のレーダ画像と第２のレーダ画像との間のコヒーレンスが推定される。 Next, the operation of the moving target detection apparatus according to the third embodiment of the present invention will be described.
Since the operation of the moving target detection apparatus according to the first embodiment is different from the operation of estimating the coherence ρ, only the added operation will be described.
The first complex signal composing the first radar image and the second complex signal composing the second radar image are obtained between the first radar image and the second radar image by the coherence estimating means 26. Coherence is estimated.

予め定められたコヒーレンスを代入して確率密度を算出する場合、実際のコヒーレンスが予め定められたコヒーレンスからずれたとき確率密度から算出するしきい値もずれてしまい移動目標の検出性能が低下してしまう可能性があるが、この発明に係る実施の形態３による移動目標検出装置のように、確率密度を実際のレーダ画像から推定したコヒーレンスを代入して算出すると、推定したコヒーレンスが実際のコヒーレンスからずれないので、確率密度から算出するしきい値もずれず移動目標の検出性能を一定に保つことができる。   When calculating the probability density by substituting the predetermined coherence, when the actual coherence deviates from the predetermined coherence, the threshold value calculated from the probability density also deviates and the moving target detection performance decreases. However, when the probability density is calculated by substituting the coherence estimated from the actual radar image as in the moving target detection apparatus according to the third embodiment of the present invention, the estimated coherence is calculated from the actual coherence. Since there is no deviation, the threshold value calculated from the probability density does not deviate and the moving target detection performance can be kept constant.

この発明に係る実施の形態１による移動目標検出装置を用いて観測するときのジオメトリを表す。The geometry at the time of observing using the moving target detection apparatus by Embodiment 1 which concerns on this invention is represented. この発明に係る実施の形態１による移動目標検出装置の構成図である。It is a block diagram of the movement target detection apparatus by Embodiment 1 which concerns on this invention. この発明に係る実施の形態１による移動目標検出装置での送受信の際の送受信アンテナ１の位置関係を示す図である。It is a figure which shows the positional relationship of the transmission / reception antenna 1 at the time of transmission / reception in the moving target detection apparatus by Embodiment 1 which concerns on this invention. 移動目標検出装置がＤＰＣＡ条件を満たしていないときに観測するクラッタを計算機により模擬し複素信号平面上に図示した図である。It is the figure which simulated the clutter observed when a moving target detection apparatus does not satisfy | fill DPCA conditions with the computer, and showed it on the complex signal plane. この発明に係る実施の形態２による移動目標検出装置の構成図である。It is a block diagram of the movement target detection apparatus by Embodiment 2 which concerns on this invention. この発明に係る実施の形態３による移動目標検出装置の構成図である。It is a block diagram of the movement target detection apparatus by Embodiment 3 which concerns on this invention.

符号の説明Explanation of symbols

１ 送受信アンテナ、２、３ アンテナ、５ａ、５ｂ、６ａ、７ｂ 電気的位相中心位置、８ 送信機、９ａ、９ｂ 送受切換器、１０ａ、１０ｂ 受信機、１１ 遅延手段、１２ａ、１２ｂ 画像再生手段、１３ 複素共役手段、１４ 乗算手段、１８ 点、１９ 等確率密度線、２０ しきい値算出手段、２１ 位置ずれ算出手段、２２ 対地速度センサ、２３ しきい値読み出し手段、２４ しきい値テーブル算出手段、２５ しきい値記憶手段、２６ コヒーレンス推定手段、２７ プリサム手段、３０ レーダプラットフォーム、３１ フットプリント、３２ 移動目標、３３ａ、３３ｂ 記憶手段、３４ 検出手段、３５ アンテナパターン記憶手段。   DESCRIPTION OF SYMBOLS 1 Transmission / reception antenna, 2, 3 Antenna, 5a, 5b, 6a, 7b Electrical phase center position, 8 Transmitter, 9a, 9b Transmission / reception switcher, 10a, 10b Receiver, 11 Delay means, 12a, 12b Image reproduction means, 13 complex conjugate means, 14 multiplication means, 18 points, 19 equal probability density lines, 20 threshold value calculation means, 21 position deviation calculation means, 22 ground speed sensor, 23 threshold value reading means, 24 threshold value table calculation means , 25 threshold storage means, 26 coherence estimation means, 27 presum means, 30 radar platform, 31 footprint, 32 moving target, 33a, 33b storage means, 34 detection means, 35 antenna pattern storage means.

Claims (3)

プラットフォームの移動方向に分割された２つの開口を持ち且つパルス繰り返し間隔でパルスが発信されるアンテナ、一方の上記開口で受信されたパルスが変換された第１の複素信号をパルス繰り返し間隔分遅延する遅延手段、上記遅延された所定数の第１の複素信号から第１のレーダ画像を再生する第１の画像再生手段、および上記一方の開口で受信されたパルスから上記パルス繰り返し間隔分遅れて発信され且つ他方の上記開口で受信されたパルスが変換された所定数の第２の複素信号から第２のレーダ画像を再生する第２の画像再生手段を備える移動目標検出装置において、
上記第２のレーダ画像を構成する第２の複素信号の複素共役を求める複素共役手段と、
上記第１のレーダ画像を構成する第１の複素信号に上記第２のレーダ画像の複素共役の信号を乗算して積の複素信号を求める乗算手段と、
上記プラットフォームの対地速度を求める手段と、
上記パルス繰り返し間隔の間に上記アンテナが移動した距離と上記アンテナの開口長の４分の１との差を算出する手段と、
上記アンテナのアンテナパターンを記憶する手段と、
上記差およびコヒーレンスに基づいてしきい値を算出する手段と、
上記算出したしきい値と上記乗算手段の積の複素信号の振幅と位相とに基づいて移動目標からの信号を検出する手段と、
を備えたことを特徴とする移動目標検出装置。 An antenna having two openings divided in the moving direction of the platform and transmitting a pulse at a pulse repetition interval, and delaying a first complex signal obtained by converting a pulse received at one of the openings by the pulse repetition interval Delay means, first image reproduction means for reproducing a first radar image from a predetermined number of delayed first complex signals, and transmission delayed by the pulse repetition interval from the pulse received at the one aperture In the moving target detection apparatus comprising second image reproduction means for reproducing the second radar image from a predetermined number of second complex signals obtained by converting the pulses received at the other opening.
Complex conjugate means for obtaining a complex conjugate of the second complex signal constituting the second radar image;
Multiplying means for multiplying a first complex signal constituting the first radar image by a complex conjugate signal of the second radar image to obtain a complex signal of the product;
Means for determining the ground speed of the platform;
Means for calculating a difference between a distance traveled by the antenna during the pulse repetition interval and a quarter of an aperture length of the antenna;
Means for storing an antenna pattern of the antenna;
Means for calculating a threshold based on the difference and coherence;
Means for detecting a signal from the moving target based on the amplitude and phase of the complex signal of the product of the calculated threshold and the multiplication means;
A moving target detection apparatus comprising: 上記パルス繰り返し間隔の間に上記アンテナが移動すると想定する複数の距離と上記アンテナの開口長の４分の１との差に基づいて予め複数のしきい値を算出ししきい値テーブルに記憶する手段と、
しきい値テーブルが格納される手段と、
上記差を算出する手段が算出した差に基づいて上記しきい値テーブルから対応するしきい値を読み出す手段と、
を備えたことを特徴とする請求項１に記載の移動目標検出装置。 A plurality of threshold values are calculated in advance based on the difference between a plurality of distances assumed to move the antenna during the pulse repetition interval and a quarter of the opening length of the antenna, and are stored in the threshold value table. Means,
Means for storing the threshold table;
Means for reading a corresponding threshold value from the threshold table based on the difference calculated by the means for calculating the difference;
The moving target detection apparatus according to claim 1, further comprising: 上記第１の画像再生手段および上記第２の画像再生手段により再生された２つのレーダ画像のコヒーレンスを求める手段を備えたことを特徴とする請求項１または２に記載の移動目標検出装置。   3. The moving target detection apparatus according to claim 1, further comprising means for obtaining coherence between two radar images reproduced by the first image reproduction means and the second image reproduction means.
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