JP4630767B2 - Radar equipment - Google Patents

Description

  The present invention relates to a step-frequency radar device that suppresses clutter and forms a high distance resolution to detect a target.

  According to the pulse compression radar that transmits a chirp signal to which linear FM modulation is applied toward the space, high resolution in the distance direction can be obtained by pulse compression at the time of reception. (For example, refer nonpatent literature 1.).

  The pulse compression radar can obtain higher distance resolution by widening the chirp bandwidth ΔF in the transmission pulse signal. However, the expansion of the chirp bandwidth ΔF with continuous frequency increases the instantaneous bandwidth in transmission and reception. Since the configuration of the antenna and the transmitter / receiver is difficult, there is a limit to increase the distance resolution by increasing the chirp bandwidth ΔF.

  Therefore, in order to obtain a high distance resolution without greatly expanding the instantaneous band, a step frequency type radar apparatus that transmits and receives by changing the frequency of the narrow band in steps has been proposed. (See, for example, pp. 200-209 of Non-Patent Document 2 and Non-Patent Document 3.)

  According to the step frequency type radar apparatus, a pulse signal composed of N (plural) pulses (f1, f2,... Fn,..., FN) in which a narrowband frequency is changed in steps is transmitted and received. Sometimes, a high distance resolution equivalent to that of a broadband chirp signal can be obtained by pulse compression for each pulse and step frequency synthesis by FFT (Fast Fourier Transform) synthesis.

  A conventional step-frequency radar device is configured as shown in FIG.

  That is, the step & chirp signal generator 1 generates a pulse signal having a step frequency and supplies it to the transmission amplifier 2.

  As shown in FIG. 8A, the pulse signal generated in the step & chirp signal generator 1 has a pulse width τ and is composed of pulses formed with a pulse repetition period (PRI). Then, as shown in FIG. 8B, there is an interval (step) of the step frequency Δf, and within the period of CPI (Coherent Processing Interval), that is, MTI (Moving Target Indicator) at the time of reception, It is formed so as to change over the range of the frequency F within a period necessary for completing processing such as DFT (Digital Fourier Transform). In the step-frequency radar apparatus, the wider the frequency F range, the higher the distance resolution at the time of reception.

  The pulse signal generated by the step & chirp signal generator 1 is up-converted to a frequency necessary for transmission from the antenna, supplied to the transmission amplifier 2, transmitted and amplified by the transmission amplifier 2, and then the circulator 3 and the adaptive signal. It is radiated into space via an antenna 4 made of an array.

  The reflected pulse signal radiated to the space via the antenna 4, reflected by the target and received via the antenna 4 is supplied to the receiver 5 via the circulator 3.

  The receiver 5 includes a high-frequency amplifier circuit, a frequency conversion circuit, and an A / D conversion circuit. The target reflected pulse signal supplied via the circulator 3 is amplified, converted into an intermediate frequency signal (IF), and further digitally converted. After conversion to a signal, the signal is supplied to the pulse compressor 6.

  The reflected pulse signal supplied to the pulse compressor 6 is subjected to pulse compression for each narrow-band pulse, and then supplied to the step frequency synthesizer 7.

  The step frequency synthesizer 7 performs FFT synthesis on the pulse-compressed reflected pulse signal, and generates and outputs a high-resolution target detection signal in the distance direction having a pulse width of 1 / F.

  The output signal of the step frequency synthesizer 7 is supplied and displayed on a display (not shown) or the like through processing such as angle measurement with respect to the target, distance measurement processing, and moving target detection.

In FIG. 7, the radar controller 8 comprehensively controls the transmission / reception function of the radar and supplies a timing signal necessary for generating a transmission pulse signal to the step & chirp signal generator 1.
IEICE "Revised Radar Technology" pp.275-278 (1996) Donald R. Wehner `` High-Resolution Radar Second Edition '' Artech House (1995) Jae Sok Son `` Range-Doppler Radar Imaging and Motion Compensation '' Artec House (2001), pp.13-15

  As described above, even if a chirp signal with a wide continuous frequency range cannot be formed due to radio wave acquisition restrictions, etc., the stepped frequency radar device can transmit and receive pulse signals that spread in a narrow band of steps. Thus, a high resolution in the distance direction can be obtained.

  In the step-frequency radar device, the pulse signal that forms a narrow-band frequency in a step-like manner is formed in addition to the reason that the expansion of the chirp band makes the configuration of the transmitting / receiving device difficult, as described above. This is because there is a restriction on radio wave acquisition that the wide frequency band cannot be occupied.

  Therefore, due to radio wave acquisition restrictions, when the step frequency signal is formed over the frequency F, there may be a case where the step frequency Δf must be increased in an unavoidable manner.

  However, even if a high resolution is obtained in the distance direction, if the step frequency Δf is widened and the number of steps (N) is reduced as a result in the step frequency type radar apparatus, the result shown in FIG. As shown in the amplitude, the level of the distance side lobe rises, and the grating lobes S1 and S2 are generated with periodicity at a distance of 1 / Δf from the main lobe L.

  In this way, the grating lobes S1 and S2 are generated in the distance region closer to the main lobe L as the interval of the step frequency Δf increases, so even if a high distance resolution is obtained, it is affected by the influence of clutter or the like. Phenomenon that target detection function and target tracking ability declined occurred.

  Accordingly, the present invention solves the above-described conventional problems, and provides a radar device that can suppress a grating lobe and obtain a high resolution in the distance direction while suppressing clutter and obtaining a good target detection function and target tracking capability. The purpose is to provide.

The first of the present invention, a radar chirp signal Ri Do steps frequency pulse signals are arranged in this stepwise and radiated into space through the antenna, detecting a target reflected pulse signals by pulse-compressed combined In the apparatus, the reflected pulse signal received via the antenna is introduced, pulse compression means for pulse compression based on complex weights, and FFT synthesis is performed on the reflected pulse signal pulse-compressed by the pulse compression means. Output step frequency synthesis means, and weight control means for controlling complex weights during pulse compression of the pulse compression means, the weight control means receiving range side lobes in the output signal of the step frequency synthesis means The complex weight is controlled so as to reduce the sensitivity.

The second of the present invention, a radar chirp signal Ri Do steps frequency pulse signals are arranged in this stepwise and radiated into space through the antenna, detecting a target reflected pulse signals by pulse-compressed combined In the apparatus, step frequency synthesizing means for performing FFT synthesis on the reflected pulse signal received via the antenna and outputting it, and pulse-compressing the reflected pulse signal synthesized by the step frequency synthesizing means based on a complex weight And a weight control means for controlling a complex weight at the time of pulse compression of the pulse compression means. The weight control means receives the range side lobe in the output signal of the pulse compression means. The complex weight is controlled so as to reduce the sensitivity.

  In the first and second aspects of the present invention, in the step frequency type radar apparatus, the output waveform by pulse compression and step frequency synthesis at the time of reception is the signal waveform on the distance axis after pulse compression and the distance by step frequency synthesis. This is due to multiplication with the signal waveform on the axis, and it was made by focusing on the fact that the response characteristic of the reception sensitivity in the distance region where the side lobe level increases can be reduced by controlling the complex weight in pulse compression. Is.

  That is, the radar apparatus according to the first and second aspects of the present invention includes weight control means, and controls the complex weight in the pulse compression means so that the response characteristic of the reception sensitivity in the distance region where the grating lobe is formed is lowered. Therefore, even when the interval of the step frequency Δf has to be widened due to restrictions on radio wave acquisition, it is possible to obtain a good target detection function and target tracking capability by suppressing clutter while forming a high resolution in the distance direction. it can.

  An embodiment of a radar apparatus according to the present invention will be described below with reference to FIGS. The same components as those of the conventional configuration shown in FIGS. 7 and 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 1 is a block diagram showing a first embodiment of a radar apparatus according to the present invention.

  That is, based on the timing signal supplied from the radar controller 8, the step & chirp signal generator 1 generates a pulse signal having a step frequency, and after up-converting to a frequency necessary for transmission from the antenna, This is supplied to the transmission amplifier 2.

  The pulse signal generated by the step & chirp signal generator 1 includes N (multiple) (f1, f2,... Fn,... FN) narrow-band pulses having a frequency F within the CPI period. As shown in FIG. 2 (a), each pulse having a pulse width τ has a pulse repetition period (PRI), and between adjacent pulse signals, as shown in FIG. As shown in b), it is formed to have an interval of the step frequency Δf. In addition, in the step frequency, the frequency of each step-like pulse may be constant, but in the present embodiment, it will be described as having a narrow band chirp frequency.

  The pulse signal supplied from the step & chirp signal generator 1 to the transmission amplifier 2 is radiated to the space via the circulator 3 and the antenna 4, and the pulse signal radiated to the space via the antenna 4 is reflected by the target. The signal is received by the antenna 4 and supplied to the receiver 5 through the circulator 3.

  The receiver 5 includes a high-frequency amplification circuit, a frequency conversion circuit, and an A / D conversion circuit. The reception pulse signal supplied via the circulator 3 is high-frequency amplified and converted into an intermediate frequency signal (IF). D is converted into a digital signal and output.

  The received pulse signal is converted into a quadrature digital (I, Q) signal x (r, n) by the A / D conversion circuit of the receiver 5 and supplied to the pulse compressor 6.

  In the quadrature digital (I, Q) signal x (r, n) supplied to the pulse compressor 6, that is, the received signal x (r, n), r is a range (distance) cell number (r = 1 to R). (Plurality)), n represents the frequency number (n = 1 to N) of the step frequency.

  Therefore, the radar apparatus according to the first embodiment is different from the conventional radar apparatus shown in FIG. 7, and the pulse compressor 6 is supplied with a received signal x (r, n) as described below. On the other hand, based on the complex weight supplied from the weight controller 9, pulse compression is performed so as to reduce the reception sensitivity of the range side lobe region, and the pulse is supplied to the step frequency synthesizer 7.

  The pulse compression operation of the pulse compressor 6 based on the complex weight for the received signal x (r, n) is compared with the pulse compression operation of the pulse compressor 6 in the conventional radar apparatus shown in FIG. This will be described below.

  The characteristic curve shown by the solid line in FIG. 2C corresponds to the amplitude waveform of the step frequency synthesized signal in the conventional radar apparatus shown in FIG. 8C, and the step in the step frequency synthesizer 7 shown in FIG. The signal amplitude waveform of frequency synthesis is shown.

  On the other hand, the characteristic curve indicated by the dotted line in FIG. 2C shows the response characteristic of the reception sensitivity formed based on the complex weight supplied from the weight controller 9 in the pulse compressor 6 shown in FIG. Is.

・・・・（１）
但し、
ＦＴｒ ： レンジセルｒに関するフーリエ変換
ＦＴ ： フーリエ変換
ＩＦＴｆ ： チャープ周波数ｆ（ｆ＝１〜Ｒ）に対する逆フーリエ変換
＊ ： 複素共役
ｆ ： チャープ周波数
Ｘ（ｆ，ｎ） ： ｘ（ｔ）のフーリエ変換
Ｗ（ｆ，ｎ） ： パルス圧縮時の複素ウェイト
ｘr（ｒ，ｎ） ： パルス圧縮後の信号
ｒｆ ： パルス圧縮用参照信号
を表す。 That is, in the radar apparatus according to the first embodiment shown in FIG. 1, the received signal x (r, n) supplied from the receiver 5 is complexed from the weight controller 9 in the pulse compressor 6. Based on the weight, pulse compression is applied to a narrow-band received pulse signal whose frequency changes stepwise sequentially. The pulse compression in the pulse compressor 6 is performed by the following equation (1). In addition, the pulse compression based on the following formula (1) is described in, for example, Non-Patent Document 1 and Non-Patent Document 2, particularly pp149-153 and pp174-177.

(1)
However,
FTr: Fourier transform for range cell r FT: Fourier transform IFTf: Inverse Fourier transform for chirp frequency f (f = 1 to R) *: Complex conjugate f: Chirp frequency X (f, n): Fourier transform of x (t) W (F, n): Complex weight at the time of pulse compression xr (r, n): Signal after pulse compression rf: Reference signal for pulse compression
Represents.

・・・・（２）
但し、
Ｂ ： チャープ帯域幅
τ ： パルス幅
ｔ ： 時間
を表す。 That is, the pulse compression in the pulse compressor 6 is based on the complex weight W (f, n) from the weight controller 9 and is a known reference for pulse compression supplied from the radar controller 8 via the weight controller 9. The correlation calculation is performed between the signal rf and the received signal x (r, n) supplied from the receiver 5, and as described above, the correlation calculation is performed by the FFT calculation shown in the above equation (1). Done. The pulse compression reference signal rf supplied from the radar controller 8 is expressed by the following equation (2).

(2)
However,
B: Chirp bandwidth
τ: Pulse width
t: represents time.

  Therefore, in the radar apparatus shown in FIG. 1, when the pulse compressor 5 performs the pulse compression based on the complex weight W (f, n) supplied from the weight controller 9, the received signal x ( The response characteristic of the reception sensitivity with respect to r, n) appears as shown by the dotted line in FIG.

  Therefore, as shown in an enlarged view of the main part in FIG. 3, the weight controller 9 has a reception sensitivity response characteristic over the areas of the grating lobes S1 and S2 generated in the distance direction across the observation range of the main lobe L. The complex weight W (f, n at the time of sufficient convergence is obtained by calculation according to the following equation (3) so that a plurality (M) (1, 2,..., M) of null points are formed. , P = convergence time) is generated and supplied to the pulse compressor 6.

・・・・ （３）
但し、
ｐ ： 収束するまでの演算回数
μ ： ステップサイズ
ｍ ： ヌル形成ポイント番号（ｍ＝１〜Ｍ）
Ｆ（ｎ） ：ステップ周波数（ｎ＝１〜Ｎ）
ｔ０ ： パルス圧縮処理の基準レンジセルに対応する時間
ｔｍ ： パルス圧縮時にヌルを形成するレンジセルに対応する時間
Ｒ０ ： パルス圧縮処理の基準レンジに対応する距離
Ｒｍ ： パルス圧縮処理の基準レンジに対応するヌルを形成するレンジ
ｃ ： 光速
を示す。 Equation (3) below is an MSN (Maximum Signal to Noise Ratio) method of the feedback loop. The MSN method shown in Equation (3) below increases the side lobe level and forms a grating lobe. The complex weight W (f, n, p = convergence time) is generated and supplied to the pulse compressor 6 so that a null point is formed in the reception sensitivity response characteristic. For the feedback loop MSN method, see Noriyoshi Kikuma, “Adaptive Signal Processing with Array Antennas”, Science and Technology Publication (1999), pp. 199 67-86.

(3)
However,
p: Number of operations until convergence
μ: Step size
m: Null formation point number (m = 1 to M)
F (n): Step frequency (n = 1 to N)
t0: Time corresponding to the reference range cell for pulse compression processing
tm: time corresponding to a range cell that forms null during pulse compression
R0: Distance corresponding to the reference range of pulse compression processing
Rm: Range that forms a null corresponding to the reference range of pulse compression processing
c: Indicates the speed of light.

  In the pulse compressor 6, an output signal xr (r) in which a plurality (M) of null points of response characteristics in the reception sensitivity are formed in the distance region of the grating lobes S 1 and S 2 generated across the observation range of the main lobe L. , N) is supplied to the step frequency synthesizer 7.

・・・・（４）
但し、
Ｘstep（ｒ） ： レンジセル番号ｒ毎に更にＮポイントに分割した信号
ＦＴｎ ： 周波数ｎに関するフーリエ変換
を表す。 The step frequency synthesizer 7 performs the output (Xstep (r)) further divided into N points in the distance direction for each range cell number r by performing FFT (Fourier transform) synthesis on the step frequency according to the following equation (4). Can be obtained.

.... (4)
However,
Xstep (r): signal further divided into N points for each range cell number r FTn: Fourier transform for frequency n.

  In the above equation (4), for simplification, it is described as an equation that does not include a window function at the time of Fourier transform, but may be an equation that includes a window function.

  As described above, in the radar apparatus of this embodiment, the output amplitude by pulse compression and step frequency synthesis is obtained by multiplying the signal waveform on the distance axis after pulse compression by the signal waveform on the distance axis by step frequency synthesis. In the pulse compressor 6, a plurality of (M) null points of the response characteristic in the reception sensitivity are formed in the distance region of the grating lobes S1 and S2 generated across the observation range of the main lobe L. The response characteristic of the reception sensitivity in the distance region where the side lobe level increases decreases, and clutter can be suppressed to obtain a good target detection function and target tracking capability.

  In the above description, the weight controller 9 sets the complex weight so that M null points of the reception sensitivity response characteristic are formed in the distance direction in which the grating lobes S1 and S2 are generated. As shown, a so-called level constraint may be adopted so that the response characteristic of the reception sensitivity is constant in the observation range region in the distance direction centered on the main lobe L. As for the MSN method with level constraint, Nobuyoshi Kikuma, “Adaptive signal processing by array antenna” Science and Technology Publication (1999), pp. 87-98.

  Further, the complex weight for pulse compression may be changed for each range cell (that is, filter bank) corresponding to the step frequency Δf, but in order to reduce the processing load in the pulse compressor 6, it is common to each range cell. The complex weight may be used.

  When a common complex weight is used in each range cell, the reception sensitivity level is constant (1, 2,... Mc) within the observation range in the distance direction as shown in FIG. Sensitivity response characteristics are reduced or approached to zero so that grating lobes S1 and S2 do not occur in other range cells.

  In the above description, it has been described that the complex weight is calculated by the weight controller 9 using a feedback loop such as the MSN method. Similarly, the null point of the response characteristic of the reception sensitivity can be formed in the distance region where the side lobe rises.

・・・・ （５）
但し、
ｒｅｓ（ｒ）： 所望のレンジセル応答
Ｗ（ｎ） ； 複素ウェイト［Ｗ（１、ｎ） Ｗ（２、ｎ）・・Ｗ（Ｒ、ｎ）］^t
ＩＦＦＴｒ［ ］； レンジセルｒに対する逆フーリエ変換
を表す。 That is, when the desired range cell response is set to res (r), the weight controller 9 receives the complex weights in the distance region of the grating lobes S1 and S2 by calculating the complex weight by the direct solution of the inverse Fourier transform according to the following equation (5). It is possible to suppress the grating lobes S1 and S2 by forming a null point of the sensitivity response characteristic. For the inverse Fourier transform, see “Spectral Analysis” by Aki Shoten (1977) pp. 18-19.

(5)
However,
res (r): desired range cell response W (n); complex weight [W (1, n) W (2, n) ·· W (R, n)] ^t
IFFTr []; Inverse Fourier transform for range cell r
Represents.

・・・・ （６）
但し、
Ｘ(ｎ) ； Ｘ（ｆ，ｎ）からなる行列
Ｒｘｘ（ｎ） ； 相関行列
Ｒｘｙ（ｎ） ； 相関行列
Ｗ０（ｆ，ｎ） ； 初期ウェイト
Ｗopt（ｎ）； 所望ウェイト［Ｗopt（1、ｎ） Ｗopt（2、ｎ）・・Ｗopt（Ｒ、ｎ）］^t
Ｅ［ ］；平均
ｔ ；転値
＊ ；複素共役
を表す。 In addition, the SMI (Sample Matrix Inversion) method is known as the direct solution method, but in the calculation of the complex weight by the SMI method in the weight controller 9, a desired complex weight Wopt is calculated by the following equation (6), Similarly, the grating lobes S1 and S2 can be suppressed. As for the SMI method, Nobuyoshi Kikuma, “Adaptive signal processing by array antenna” Science and Technology Publication (1999) pp. 35-37.

(6)
However,
X (n); matrix consisting of X (f, n) Rxx (n); correlation matrix Rxy (n); correlation matrix W0 (f, n); initial weight
Wopt (n); desired weight [Wopt (1, n) Wopt (2, n) · · Wopt (R, n)] ^t
E []; average
t: Inversion
* Represents a complex conjugate.

  Also in this SMI method, the constrained output minimization method can be applied, and when the constrained output minimization method is applied, the observation centered on the main lobe L as shown in FIG. In the range, the level of the grating lobe may be reduced while the level is constrained so that the response characteristic of the reception sensitivity is constant (1, 2,... Mc). For the SMI method with constraints, see Nobuyoshi Kikuma, “Adaptive Signal Processing with Array Antenna” Science and Technology Publication (1999) pp. 98-99.

  As described above, the weight controller 9 generates a pulse-compressed signal having a response characteristic of reception sensitivity that suppresses the grating lobes S1 and S2 by calculation of complex weights by calculation by direct solution without using the feedback method. The step frequency synthesizer 7 performs step frequency synthesis using the above equation (4).

  In short, according to the radar apparatus of this embodiment, the output amplitude by pulse compression and step frequency synthesis is obtained by multiplying the signal waveform on the distance axis after pulse compression by the signal waveform on the distance axis by step frequency synthesis. Therefore, the complex weight at the time of pulse compression is controlled so that the reception sensitivity response in the grating lobe generation distance region is reduced or brought close to zero, so the interval of the step frequency Δf must be widened due to restrictions on radio wave acquisition. Even in this case, it is possible to suppress clutter and obtain a good target detection function and target tracking capability under high distance resolution.

  Next, as shown in FIG. 1, the radar apparatus according to the first embodiment performs pulse compression in the pulse compressor 6 and then performs FFT synthesis in the step frequency synthesizer 7 to receive sensitivity in the side lobe. However, the output by pulse compression and step frequency synthesis is due to multiplication of the signal waveform on the distance axis after pulse compression and the signal waveform on the distance axis by step frequency synthesis. The connection relationship between the compressor 6 and the step frequency synthesizer 7 is reversed, and the step frequency synthesizer 7 first performs FFT synthesis on the received signal supplied from the receiver 5, and the pulse compressor for the synthesized signal. Even if 6 is configured to perform pulse compression by weight control, the same effect can be obtained.

  5 is a block diagram showing a second embodiment of the radar apparatus according to the present invention. The first embodiment shown in FIG. 1 differs from the first embodiment shown in FIG. 1 in the connection order of the pulse compressor 6 and the step frequency synthesizer 7. The other configurations and the operations in the respective configurations are the same as those in the first embodiment, and the complex weight calculation method in the weight controller 9 is the various calculation methods described in the first embodiment. Can be adopted.

  Therefore, also in the radar apparatus according to the second embodiment, the weight controller 9 calculates complex weights by, for example, the feedback method or the direct solution method, as in the first embodiment, and the grating lobes S1 and S2 are formed. Since the response characteristic of the reception sensitivity in the side lobe area to be reduced can be reduced, the clutter can be suppressed and a signal with improved target detection function and target tracking capability can be output as in the first embodiment. .

  In each of the first and second embodiments, the radar apparatus has a gap between adjacent pulses on the frequency axis from the viewpoint that the radar apparatus has a limitation in radio wave acquisition. Although described as being arranged, if a region of frequency F that can continuously use a relatively wide band can be formed, a step frequency is formed by dividing the region of frequency F into a plurality of portions on the frequency axis. Also good.

  That is, as shown in FIGS. 6A and 6B, the pulse signal waveform diagrams corresponding to FIGS. 2A and 2B are shown in FIG. 6B. As described above, the adjacent step frequencies (f1, f2,... FN) may be formed such that each adjacent pulse is partially overlapped or continuously formed on several axes. As described above, in the step & chirp signal generator 1, the frequency F band is divided while partially overlapping, so that the signal processing in the receiver 5 or the like is facilitated due to the restriction of the frequency band in each step. The scale can be reduced.

It is the block diagram which showed the 1st Example of the radar apparatus based on this invention. 2A and 2B are signal waveform diagrams of transmission pulse signals in the apparatus shown in FIG. 1, and FIG. 2C is a reception output signal waveform chart of the apparatus shown in FIG. FIG. 3 is an enlarged view of the output signal waveform shown in FIG. 2C, and is an explanatory diagram of reception sensitivity response characteristics in which a plurality of null points are formed, particularly in pulse compression by weight control. FIG. 3 is an explanatory diagram of a reception sensitivity characteristic indicating a constraint point in the operation characteristics of pulse compression of the apparatus shown in FIG. 1. It is the block diagram which showed the 2nd Example of the radar apparatus based on this invention. It is a signal waveform diagram of another transmission pulse signal applied to the radar apparatus according to the present invention. It is a block diagram of the conventional radar apparatus. 8A and 8B are signal waveform diagrams of transmission pulse signals in the apparatus shown in FIG. 7, and FIG. 8C is a waveform diagram of received output signals of the apparatus shown in FIG.

Explanation of symbols

1 Step & Chirp Signal Generator 2 Transmitting Amplifier 3 Circulator 4 Antenna 5 Receiver 6 Pulse Compressor (Pulse Compression Means)
7 Step frequency synthesizer (Step frequency synthesizer)
8 Weight controller (weight control means)
9 Radar controller

Claims (6)

The radar apparatus Do Ri chirp signal from the step frequency of the pulse signal are arranged in this stepwise and radiated into space through the antenna, detecting a target reflected pulse signals by pulse-compressed combined,
Pulse compression means for introducing a reflected pulse signal received via the antenna and compressing the pulse based on a complex weight;
Step frequency synthesis means for performing FFT synthesis on the reflected pulse signal pulse-compressed by the pulse compression means and outputting;
Weight control means for controlling a complex weight at the time of pulse compression of the pulse compression means,
The radar apparatus according to claim 1, wherein the weight control unit controls the complex weight so that reception sensitivity of the range side lobe in the output signal of the step frequency synthesis unit is reduced. The radar apparatus Do Ri chirp signal from the step frequency of the pulse signal are arranged in this stepwise and radiated into space through the antenna, detecting a target reflected pulse signals by pulse-compressed combined,
Step frequency synthesizing means for performing FFT synthesis on the reflected pulse signal received via the antenna and outputting it;
Pulse compression means for pulse-compressing and outputting the reflected pulse signal synthesized by the step frequency synthesis means based on complex weights;
Weight control means for controlling a complex weight at the time of pulse compression of the pulse compression means,
The radar apparatus according to claim 1, wherein the weight control means controls the complex weight so that the reception sensitivity of the range side lobe in the output signal of the pulse compression means is reduced. The radar apparatus according to claim 1, wherein the weight control unit calculates the complex weight by a feedback loop. The radar apparatus according to claim 3, wherein the calculation of the complex weight by the feedback loop is based on an MSN method. The radar apparatus according to claim 1, wherein the weight control unit calculates the complex weight by a direct solution method. The radar apparatus according to claim 5, wherein the calculation of the complex weight by the direct solution method is performed by an SMI method.

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