CN105842688A - Air target quick capturing method of monopulse radar - Google Patents

Abstract

The invention provides an air target quick capturing method of monopulse radar. By means of the method, a target searching and capturing capability of the radar can be remarkably improved on conditions of low signal-to-noise ratio and high-speed target movement, thereby realizing quick target capturing. The air target quick capturing method is realized through a technical solution which is characterized in that DSP embedded software is composed of a three-channel constant false-alarm rate detecting module, a wave beam direction adjusting module, a target parameter estimating module, a sequence position correlation module and a slide window accumulation confirmation module, wherein the method comprises the steps of inputting summation, direction difference and pitch difference three-channel distance images, performing constant false-alarm rate determination on the three-channel distance images, thereby obtaining a target signal with a highest amplitude; then changing elapse main triggering time, and adjusting the wave beam according to a designed strategy; performing target parameter estimation by means of a phase and a difference type monopulse measured angle; determining a fact that target correlation successes or fails by means of sequence position correlation; performing sliding window type accumulation on the correlation result, determining the accumulation result, and outputting the target information which is successively captured through the monopulse radar.

Description

Method for rapidly capturing air target by monopulse radar

Technical Field

The invention relates to the field of radar target searching and capturing, in particular to a method for rapidly and accurately capturing an empty high-speed moving target by a monopulse radar under a low signal-to-noise ratio.

Background

In the air search tracking radar, a designated airspace target needs to be searched before tracking guidance is implemented, and the rapid and reliable target capture is the first premise for realizing accurate target strike. The search tracking radar mostly adopts a single pulse technology to realize precise measurement and tracking of the target. Monopulse is a radar angle measurement technique, which obtains accurate target angle information by comparing sum and difference channel signals, theoretically receives an echo pulse to form an angle estimation value of a target relative to a radar, and the radar using the technique is called monopulse radar.

In order to obtain high angle measurement accuracy, the monopulse radar can reduce the width of a receiving beam, so that the instantaneous coverage area of a sum channel is reduced, if the sum channel is only used for detection, and information of two difference channels is not considered, useful information of a target can be lost, and the probability of capturing the target is extremely easy to reduce. With the increasingly mature modern stealth technology at home and abroad, the radar scattering cross section of a target is effectively reduced, so that the energy of an echo signal of the target is weaker than that of a traditional aircraft, the signal-to-noise ratio is reduced, the difficulty in detecting weak and small moving target signals in high-intensity ground clutter is increased, and the traditional method cannot achieve a satisfactory detection effect. At present, the speed of a new generation supersonic aircraft is about Mach 2, the flight speed of an unmanned aerial vehicle reaches more than 10 Mach numbers, and in the face of ultrahigh-speed and high-maneuvering flight of a target, the traditional search and tracking radar is difficult to effectively capture the target in a short time, so that the traditional search and tracking radar poses great threat to the existing radar defense system and provides a severe challenge to target search and tracking. These factors all bring great difficulty to the search and tracking radar to quickly and correctly capture the target, and how to improve the radar to quickly capture the weak and small target moving at high speed and medium air speed becomes a problem which needs to be solved urgently in the search and tracking radar development process.

The existing target search capture method is mainly researched: (1) the radar transmitting and receiving front end is improved, and the signal to noise ratio of a target echo is improved; (2) by accumulating the target signal, the detection probability is improved. The method (1) is usually used for increasing the transmitting power, improving the gain of an antenna and a channel, reducing the noise of a receiver and the like, has strict requirements on the power, the size and basic hardware of the radar, is easy to expose the radar and be attacked by an anti-radiation weapon, is limited by a plurality of practical conditions in the implementation and has high engineering use difficulty; in the signal processing, the output signal-to-noise ratio is improved by carrying out coherent and non-coherent accumulation on a plurality of time series pulses, but the target cannot move away from the unit within the accumulation time, so that the accumulation time of the target moving at high speed and medium air is limited, and the target cannot be accumulated for a long time; in addition, most of the methods only consider sum channel detection, ignore difference channel information, and may lose targets appearing in the difference channels and capture the targets.

Disclosure of Invention

In order to solve the problem of searching and capturing the air high-speed moving weak and small targets by a searching and tracking radar, the invention aims to provide a monopulse radar quick capturing method which can shorten the radar searching time and improve the target capturing probability, so that the target searching and capturing capacity of the radar under the conditions of low signal-to-noise ratio and high-speed movement of the target is improved, and the quick capturing of the air target is realized.

In order to achieve the purpose, the invention provides a method for rapidly capturing an empty target by a monopulse radar, which is characterized by comprising the following steps of: in terminal processing extension DSP embedded software, the DSP embedded software uses a three-channel constant false alarm detection module, a beam direction adjustment module, a target parameter estimation module, a sequence position correlation module and a sliding window accumulation confirmation module as units to construct a single pulse radar empty target rapid capturing processing framework, wherein the three-channel constant false alarm detection module counts background noise mean value and standard difference according to sum, azimuth difference and elevation difference three-channel distance image signals output by a signal processing extension, determines a threshold multiplier according to false alarm probability, calculates a constant false alarm self-adaptive detection threshold, and simultaneously carries out detection judgment on the three-channel distance image to obtain a target signal with maximum amplitude; the beam pointing adjustment module calculates the pushing main trigger time of signal acquisition by using the target distance, carries out beam pointing adjustment according to a design strategy within the maximum adjustment times, and finishes beam adjustment when the sum channel detects a target and the sum channel signal is greater than the azimuth difference and pitch difference channel signals; the target parameter estimation module uses a target signal detected by the sum channel to gate a corresponding difference channel signal, performs phase and difference type single pulse angle measurement, estimates the deviation of a target azimuth angle and the deviation of a pitch angle, calculates the azimuth angle and the pitch angle by using the beam pointing direction, estimates the deviation of the target azimuth angle and the pitch angle, and then calculates the azimuth angle and the pitch angle by using the beam pointing direction; the sequence position association module converts the target distance, the azimuth angle and the pitch angle into observed values under a rectangular coordinate system, calculates Euclidean distances of the target observed values at the front moment and the rear moment, and judges whether the target association is successful or failed by taking the maximum motion speed as a criterion; the sliding window accumulation confirming module represents the result of successful or failed target sequence position association by 0 or 1, then the association result is accumulated in a sliding window mode, the accumulated result is judged, and target information which is successfully acquired is searched and acquired through the output of a single pulse radar, so that the fast acquisition of the weak and small target which moves at high speed and in the air is realized.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a method for rapidly capturing an empty high-speed moving target by a monopulse radar aiming at low signal-to-noise ratio and high-speed movement of the target, which comprises the following steps: inputting sum and difference three-channel distance images, calculating a constant false alarm adaptive detection threshold by using the three-channel distance images by using a three-channel constant false alarm detection module, and simultaneously carrying out detection judgment on the three-channel distance images to obtain a target signal with the maximum amplitude; changing the main triggering time of signal acquisition, and adjusting the beam pointing direction according to a design strategy to enable a sum channel to detect a target and simultaneously meet the condition that the sum channel signal is greater than the azimuth difference and the pitch difference channel signals; performing target parameter estimation on a difference channel signal corresponding to the target signal detected by the channel by using phase and difference single pulse angle measurement; converting the target measured values, calculating Euclidean distances of the target observed values at two moments before and after, and judging whether the target association is successful or failed by taking the maximum motion speed as a criterion; and (4) performing sliding window type accumulation on the correlation result, judging the accumulation result, and outputting target information which is searched and captured successfully through a monopulse radar, thereby realizing the rapid capture of the weak and small target moving at high speed. Compared with the existing method, the existing system of the radar does not need to be changed, only the terminal processing flow and the method are optimized, and finally the method is realized by adopting DSP software, so that the method is convenient to transplant and upgrade, and is easy to operate and realize in engineering application.

According to the invention, three-channel range profile echo signals of the sum, azimuth difference and pitching difference are fully utilized, and a sum-difference channel joint detection method is adopted, which is equivalent to increasing the beam width of scanning search, mining useful information of a target, improving the discovery probability of the target and shortening the target capture time; in order to prevent the loss of the high-speed moving target, a target locking mode is adopted, and meanwhile, the condition that the target can not meet the single-pulse angle measurement condition is considered, and a beam adjustment strategy is designed so that the beam can be adjusted to be aligned with the target under different conditions; by carrying out sliding window type accumulation confirmation on the result of target sequence position correlation, the confirmation of the target under low signal-to-noise ratio can be achieved, and the target searching and capturing accuracy is further improved.

The invention provides a solution and a solid foundation for the search and capture of the air high-speed target by the monopulse radar under the low signal-to-noise ratio.

Drawings

For a more clear understanding of the invention, it will now be further elucidated by way of the accompanying drawings and examples, in which:

FIG. 1 is a flow chart of the method for rapidly capturing an empty target by a monopulse radar of the invention.

Fig. 2 is a flow chart of the beam pointing adjustment module of the present invention.

Detailed Description

The invention will be further explained with reference to the drawings.

See fig. 1. In the embodiment described below, the whole process of the air target fast capturing method of the monopulse radar is automatically implemented in the terminal processing extension by using a DSP embedded software mode. The DSP embedded software takes a three-channel constant false alarm detection module, a beam direction adjustment module, a target parameter estimation module, a sequence position association module and a sliding window accumulation confirmation module as units to construct a single-pulse radar empty target rapid capturing software architecture, wherein (S1) the three-channel constant false alarm detection module counts the mean value and the standard deviation of background noise according to sum, azimuth difference and pitch difference three-channel distance image signals output by a signal processing extension, determines a threshold multiplier according to the false alarm probability, calculates a constant false alarm self-adaptive detection threshold, and simultaneously carries out detection judgment on the three-channel distance image to obtain a target signal with the maximum amplitude; (S2) the beam pointing adjustment module calculates the pushing main trigger time of signal acquisition by using the target distance, carries out beam pointing adjustment according to a design strategy within the maximum adjustment times, and finishes beam adjustment when the sum channel detects a target and the sum channel signal is greater than the azimuth difference and the elevation difference channel signal; (S3) the target parameter estimation module uses the difference channel signal corresponding to the target signal gating of the channel detection to measure the angle of the phase and difference type monopulse, estimates the deviation of the target azimuth angle and the deviation of the pitch angle, and then calculates the azimuth angle and the pitch angle by using the beam pointing; (S4) the sequence position association module converts the target distance, the azimuth angle and the pitch angle into observed values under a rectangular coordinate system, calculates Euclidean distances of the target observed values at the front moment and the rear moment, and judges the success or failure of target association by taking the maximum motion speed as a criterion; (S5) the sliding window accumulation confirmation module represents the result of successful or failed target sequence position association by 0 or 1, then carries out sliding window accumulation on the association result, judges the accumulation result, and outputs, searches and captures successful target information through a monopulse radar.

Each module comprises the following specific steps:

in the three-channel constant false alarm detection, the three-channel constant false alarm detection module calculates the background noise mean value mu and the standard deviation sigma by using the three-channel distance images of the sum, the azimuth difference and the pitch difference

$\mathrm{\μ}=\frac{1}{n}\underset{i=1}{\overset{n}{\Σ}}{A}_i---\left(1\right)$

$\mathrm{\σ}=\sqrt{\frac{1}{n}\underset{i=1}{\overset{n}{\Σ}}{(A_i-\mathrm{\μ})}^2}---\left(2\right)$

Wherein,A_iis a three-channel range image magnitude value, I_iAnd Q_iThe IQ two-path orthogonal signals of the range profile echo signals are provided, and n is the total number of samples participating in statistics.

The three-channel constant false alarm rate detection module assumes that background noise obeys Gaussian distribution, and determines a threshold multiplier K according to the constant false alarm rate; the three-channel constant false alarm rate detection module calculates a three-channel distance image constant false alarm rate self-adaptive detection threshold U by using the calculated background mean value mu and the threshold multiplier K₁

The three-channel constant false alarm detection module utilizes the calculated constant false alarm self-adaptive detection threshold U₁Range image amplitude A of three channels of pair sum, azimuth difference and pitching difference_i∈{A_∑,A_Δ1,A_Δ2In which A_∑To sum channel amplitude, A_Δ1Is the azimuth channel amplitude, A_Δ2Is the pitch difference channel amplitude) while making a detection decision, will

If A_i≥U₁Is judged as a target signal

If A_i＜U₁Is judged as a noise signal

If a plurality of signals pass the detection threshold judgment, the three-channel constant false alarm detection module only takes the distance unit with the maximum signal amplitude as a target signal for subsequent processing, and records the sum and difference channel number, the distance image unit serial number and the echo signal amplitude.

See fig. 2. In the beam pointing adjustment, the beam pointing adjustment module utilizes the three-channel distance image starting distance R for the maximum amplitude target signal acquired by the three-channel constant false alarm detection module_startDistance unit length r_unitAnd the sequence number k of the distance unit where the target signal is located, calculating the target distance R_k

R_k＝R_start+r_unit×k (4)

Beam pointing adjustment module calculates lapse main trigger time t of signal acquisition by using target distance_AD

$t_{AD}=\frac{2R_k}{C}---\left(5\right)$

Where C is the electromagnetic wave propagation velocity.

The beam pointing adjustment module sets the maximum adjustment times K of the beam, and when the adjustment times of the beam is less than or equal to K, the beam can be continuously adjusted to point to the detection target; and when the beam adjustment times are more than K, stopping the beam adjustment and scanning according to the planned search route sequence. If the target is not detected in the sum channel, the beam pointing adjustment strategy of the beam pointing adjustment module carries out beam adjustment according to the following sequence

1) The azimuth is forward deviated by half the beam width, and the pitching direction is unchanged;

2) the azimuth direction deflects back half beam width, and the elevation direction deflects forward half beam width;

3) the azimuth direction reversely deflects by half the beam width, and the elevation direction reversely deflects by half the beam width;

4) azimuth is back-biased by half the beamwidth, elevation is back-biased by half the beamwidth.

When the sum channel detects a target but does not meet the condition that the sum channel signal is greater than the azimuth difference and the elevation difference channel signal, the beam pointing adjustment strategy of the beam pointing adjustment module adjusts the beam in the following mode

If the sum < azimuth difference: the azimuth direction firstly deflects half beam width in the forward direction and then deflects 1 beam width in the backward direction

If the sum < pitch difference: the pitching direction firstly deflects half beam width forwards and then deflects 1 beam width backwards

The beam pointing adjustment module judges whether a target is detected in the sum channel or not after the beam pointing adjustment, and if the target is not detected in the sum channel, the beam pointing adjustment module needs to continuously adjust the beam pointing to detect the target; otherwise, the next step is processed according to the flow. The beam pointing adjustment module judges whether the sum channel signal is greater than the azimuth difference channel signal and the pitch difference channel signal, if so, the beam adjustment is finished, and the next module is used for processing; otherwise, returning to continuously adjust the beam pointing to the detection target.

In the target parameter estimation, the target parameter estimation module refers to the target signal of which the sum channel passes through the detection threshold in the beam direction adjustment module, namely the formula (4) R_k＝R_start+r_unit× k method for calculating target distance R_k。

The target parameter estimation module uses the target signal of sum channel detection to gate the corresponding difference channel signal for phase and difference singlesMeasuring pulse angle, calculating target azimuth deviation_θAnd pitch angle deviation

${\mathrm{\&epsiv;}}_{\mathrm{\&theta;}}=K_{\mathrm{\&theta;}}\frac{I_{\mathrm{\&Delta;}1}\&times;I_{\&Sigma;}+Q_{\mathrm{\&Delta;}1}\&times;Q_{\&Sigma;}}{{\left(I_{\&Sigma;}\right)}^2+{\left(Q_{\&Sigma;}\right)}^2}---\left(6\right)$

Wherein, K_θ、Respectively as azimuth and pitch angle deviation slopes; i is_∑And Q_∑Are IQ two-path orthogonal signals of sum channel, I_Δ1And Q_Δ1IQ two-path orthogonal signals, I, of azimuth difference channel_Δ2And Q_Δ2And IQ two paths of orthogonal signals of a pitch difference channel are respectively.

The target parameter estimation module calculates a target azimuth angle theta and a target pitch angle by using the beam center pointing direction given by the antenna and the calculated angle deviation

θ＝θ_Beam+_θ(8)

Wherein, theta_BeamAndpointing for antenna azimuth and elevation beam center respectively,_θandazimuth and pitch deviations, respectively.

In the sequence position correlation, a sequence position correlation module correlates a target distance R, an azimuth angle theta and a pitch angleConverting into observed value (x, y, z) under rectangular coordinate system

Sequence position correlation module calculates Euclidean distance between front and rear sequence target observed values

$D=\sqrt{{\&lsqb;x\left(k\right)-x(k-1)\&rsqb;}^2+{\&lsqb;y\left(k\right)-y(k-1)\&rsqb;}^2+{\&lsqb;z\left(k\right)-z(k-1)\&rsqb;}^2}---\left(11\right)$

Wherein, (x (k), y (k), z (k)) is a target observed value at a previous moment, and (x (k-1), y (k-1), z (k-1)) is a target observed value at a later moment. The sequence position correlation module carries out target data correlation judgment through the following criteria

If D/T_s≤V_maxThe target association is judged to be successful

If D/T_s＞V_maxJudging as the target association failure

Wherein D is the Euclidean distance of two moments before and after T_sA time interval of two preceding and succeeding moments, V_maxIs the maximum radial velocity between the radar and the target.

In the sliding window accumulation confirmation, the sliding window accumulation confirmation module indicates the result of successful or failed correlation of the target sequence position as 0 or 1, then inputs the correlation result into a sliding window with the length of N and performs sliding window accumulation, and the accumulation result is marked as M_∑And then making a decision on the accumulated result

If M is_∑≥U₂The judgment is that the target capture is successful

If M is_∑＜U₂Judging as the target capture failure

Wherein, U₂The decision threshold is cumulatively determined for the sliding window, and the value is an integer in the range of 0 < U₂N is less than or equal to N. Cumulative result M_∑And a target cumulative capture probability P_cdIn a relationship of

$P_{cd}=\underset{k=U_2}{\overset{N}{\&Sigma;}}\frac{N!}{k!(N-k)!}{p}_d^k{(1-p_d)}^{N-k}---\left(12\right)$

Wherein, N! Is a factorial of N, p_dIs the single detection probability. If the target cumulative capture probability P is known_cdThe sliding window accumulation confirming module can calculate the accumulation judgment threshold U by using the formula₂. And when the accumulation judgment is successful, the sliding window accumulation confirmation module outputs the target information at the moment as a target which is successfully searched and captured by the monopulse radar.

Claims (10)

1. A method for quickly capturing an empty target by a monopulse radar is characterized by comprising the following steps: in terminal processing extension DSP embedded software, the DSP embedded software uses a three-channel constant false alarm detection module, a beam direction adjustment module, a target parameter estimation module, a sequence position correlation module and a sliding window accumulation confirmation module as units to construct a single pulse radar empty target rapid capturing processing framework, wherein the three-channel constant false alarm detection module counts background noise mean value and standard difference according to sum, azimuth difference and elevation difference three-channel distance image signals output by a signal processing extension, determines a threshold multiplier according to false alarm probability, calculates a constant false alarm self-adaptive detection threshold, and simultaneously carries out detection judgment on the three-channel distance image to obtain a target signal with maximum amplitude; the beam pointing adjustment module calculates the pushing main trigger time of signal acquisition by using the target distance, carries out beam pointing adjustment according to a design strategy within the maximum adjustment times, and finishes beam adjustment when the sum channel detects a target and the sum channel signal is greater than the azimuth difference and pitch difference channel signals; the target parameter estimation module uses a target signal detected by the sum channel to gate a corresponding difference channel signal, performs phase and difference type single pulse angle measurement, estimates the deviation of a target azimuth angle and the deviation of a pitch angle, calculates the azimuth angle and the pitch angle by using the beam pointing direction, estimates the deviation of the target azimuth angle and the pitch angle, and then calculates the azimuth angle and the pitch angle by using the beam pointing direction; the sequence position association module converts the target distance, the azimuth angle and the pitch angle into observed values under a rectangular coordinate system, calculates Euclidean distances of the target observed values at the front moment and the rear moment, and judges whether the target association is successful or failed by taking the maximum motion speed as a criterion; the sliding window accumulation confirming module represents the result of successful or failed target sequence position association by 0 or 1, then the association result is accumulated in a sliding window mode, the accumulated result is judged, and target information which is successfully acquired is searched and acquired through the output of a single pulse radar, so that the fast acquisition of the weak and small target which moves at high speed and in the air is realized.

2. The method for rapidly capturing the empty target by the monopulse radar as claimed in claim 1, wherein: in the three-channel constant false alarm detection, the three-channel constant false alarm detection module calculates the background noise mean value mu and the standard deviation sigma by using the three-channel distance images of the sum, the azimuth difference and the pitch difference

$\mathrm{\&mu;}=\frac{1}{n}\underset{i=1}{\overset{n}{\&Sigma;}}{A}_i---\left(1\right)$

$\mathrm{\&sigma;}=\sqrt{\frac{1}{n}\underset{i=1}{\overset{n}{\&Sigma;}}{(A_i-\mathrm{\&mu;})}^2}---\left(2\right)$

Wherein,A_iis a three-channel range image magnitude value, I_iAnd Q_iThe IQ two-path orthogonal signals of the range profile echo signals are provided, and n is the total number of samples participating in statistics.

3. The method for rapidly capturing the empty target by the monopulse radar as claimed in claim 1, wherein: the three-channel constant false alarm detection module determines a threshold multiplier K according to the constant false alarm probability; calculating three-channel distance image constant false alarm rate self-adaptive detection threshold by using calculated background noise mean value mu and threshold multiplier K

4. The method for rapidly capturing the empty target by the monopulse radar as claimed in claim 3, wherein: three-channel constant false alarm rate detection module utilizes calculated constant false alarm rate self-adaptive detection threshold U₁Range image amplitude A of three channels of pair sum, azimuth difference and pitching difference_i∈{A_∑,A_Δ1,A_Δ2Fourthly, simultaneously carrying out detection judgment; if A_i≥U₁Deciding as the target signal if A_i＜U₁The decision is a noise signal, where A_∑To sum channel amplitude, A_Δ1Is the azimuth channel amplitude, A_Δ2Is a pitchThe difference channel amplitude.

5. The method for rapidly capturing the empty target by the monopulse radar as claimed in claim 4, wherein: if a plurality of signals pass the detection threshold judgment, the three-channel constant false alarm detection module only takes the distance unit with the maximum signal amplitude as a target signal for subsequent processing, and records the sum and difference channel number, the distance image unit serial number and the echo signal amplitude.

6. The method for rapidly capturing the empty target by the monopulse radar as claimed in claim 1, wherein: the beam pointing adjustment module sets the maximum adjustment times of the beam, and when the adjustment times of the beam are less than or equal to the maximum adjustment times of the beam, the beam is continuously adjusted to point to a detection target; when the beam adjustment times are more than the preset times, stopping the beam adjustment and scanning according to the planned search route sequence; if the target is not detected in the sum channel, the beam pointing adjustment strategy of the beam pointing adjustment module adjusts the beam according to the following sequence,

1) the azimuth is forward deviated by half the beam width, and the pitching direction is unchanged;

2) the azimuth direction deflects back half beam width, and the elevation direction deflects forward half beam width;

3) the azimuth direction reversely deflects by half the beam width, and the elevation direction reversely deflects by half the beam width;

4) azimuth is back-biased by half the beamwidth, elevation is back-biased by half the beamwidth.

7. The method for rapidly capturing the empty target by the monopulse radar as claimed in claim 1, wherein: when the sum channel detects a target but does not meet the condition that the sum channel signal is greater than the azimuth difference and the elevation difference channel signal, the beam pointing adjustment strategy of the beam pointing adjustment module adjusts the beam in the following way: if the sum is less than the azimuth difference, the azimuth direction firstly deviates from the half beam width forward and then deviates from the 1 beam width backward, and if the sum is less than the pitch difference, the pitch direction firstly deviates from the half beam width forward and then deviates from the 1 beam width backward; and the beam pointing adjustment module judges whether a target is detected in the sum channel or not after the beam pointing adjustment, if not, the beam pointing adjustment module needs to continuously adjust the beam pointing to detect the target, otherwise, the beam pointing adjustment module enters the next step of processing according to the flow.

8. The method for rapidly capturing the empty target by the monopulse radar as claimed in claim 1, wherein: the target parameter estimation module uses the target signal of the sum channel detection to gate the corresponding difference channel signal, makes phase and difference type single pulse angle measurement, and calculates the target azimuth angle deviation_θAnd pitch angle deviation

${\mathrm{\&epsiv;}}_{\mathrm{\&theta;}}=K_{\mathrm{\&theta;}}\frac{I_{\mathrm{\&Delta;}1}\&times;I_{\mathrm{\&Sigma;}}+Q_{\mathrm{\&Delta;}1}\&times;Q_{\mathrm{\&Sigma;}}}{{\left(I_{\mathrm{\&Sigma;}}\right)}^2+{\left(Q_{\mathrm{\&Sigma;}}\right)}^2}---\left(3\right)$

Wherein, K_θ、Respectively as azimuth and pitch angle deviation slopes; i is_∑And Q_∑Are IQ two-path orthogonal signals of sum channel, I_Δ1And Q_Δ1IQ two-path orthogonal signals, I, of azimuth difference channel_Δ2And Q_Δ2And IQ two paths of orthogonal signals of a pitch difference channel are respectively.

9. The method for rapidly capturing the empty target by the monopulse radar as claimed in claim 1, wherein: the sequence position correlation module makes a target data correlation judgment according to the following criteria: if D/T_s≤V_maxJudging that the target association is successful, if D/T_s＞V_maxJudging that the target association fails; wherein D is the Euclidean distance of two moments before and after T_sA time interval of two preceding and succeeding moments, V_maxIs the maximum radial velocity between the radar and the target.

10. The method for rapidly capturing the empty target by the monopulse radar as claimed in claim 1, wherein: the sliding window accumulation confirming module represents the result of successful or failed target sequence position association by 0 or 1, then the association result is input into a sliding window with the length of N and accumulated in a sliding window mode, and the accumulation result is recorded as M_∑And then judging the accumulated result: if M is_∑≥U₂Judging that the target capture is successful if M_∑＜U₂Judging that the target capture fails; wherein, U₂The decision threshold is cumulatively determined for the sliding window, and the value is an integer in the range of 0 < U₂≤N。