Target-based adaptive digital AGC control method

Abstract

The invention discloses a target-based adaptive digital AGC control method, which belongs to the technical field of radar control, and comprises the following steps: S1, initializing radar parameters, receiving and analyzing echo data, and obtaining a target scattering point information set; s2, clustering the target scattering point information set according to radar parameters, and extracting amplitude information of a class target; s3, determining the amplitude of the target to be tracked from the amplitude information of the class target; s4, calculating the variable quantity of the AGC control quantity according to the amplitude of the target to be tracked; s5, determining a gain adjustment amount according to the variation of the AGC control amount; and S6, completing AGC control according to the gain adjustment amount. According to the method, the amplitude of a tracking target selected by the radar is taken as a reference instead of the amplitude envelope of the whole receiving channel, so that the condition that a large target presses a small target or a strong background clutter presses the target can be prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar control, and particularly relates to an adaptive digital AGC control method based on a target. Background Art

[0002] The radar automatic gain control circuit AGC is an important part of a radar. Its function is to automatically adjust the gain of the radar receiver according to the strength of the signal in the receiving channel. When the received target signal is weak, the receiver has a high gain to ensure the detection of distant targets or small targets; when the received signal is strong, the receiver has a low gain to ensure the detection of near targets; through AGC control, no matter how far or near the detected target is, or how large the target RCS is, the signal output by the receiver is always stabilized within a suitable range.

[0003] However, the existing radar automatic gain control circuit AGC performs gain control based on the signal envelope of the entire receiving channel. Its limitation is that when a target such as a ship passes by the island shore background or leaves / enters the port, the island shore background or port background clutter is very strong, and the target signal is submerged in the strong clutter background, and the signal (clutter + target) of the entire receiving channel is very strong. If the traditional method is used, and the strongest value of the signal envelope of the entire receiving channel is used as the benchmark for the AGC control amount, at this time, the gain of the receiving channel will become extremely low, and the strong clutter will submerge the target signal, directly resulting in the inability to effectively detect the target; furthermore, if there are large and small targets at the same time, such as when a ship target passes by a signal tower, or when large and small ships meet, if the traditional method is used, and the strongest value of the signal envelope of the entire receiving channel is used as the benchmark for the AGC control amount, the gain of the receiving channel is determined according to the large target, and the situation of the large target submerging the small target will occur, affecting the effective detection of the small target.

[0004] Therefore, it is necessary to propose a new method to solve the above series of problems. Summary of the Invention

[0005] In order to solve the problems of poor ability to resist adjacent interference targets, inability to effectively detect targets in a strong clutter background, and inability to effectively detect small targets when large and small targets meet, the present invention proposes an adaptive digital AGC control method based on a target.

[0006] The technical solution of the present invention is: an adaptive digital AGC control method based on a target includes the following steps:

[0007] S1. Initialize the radar parameters, receive and analyze the echo data, and obtain the target scatter point information set;

[0008] S2. Cluster the target scatter point information set according to the radar parameters, and extract the amplitude information of the class target;

[0009] S3. Determine the amplitude of the target to be tracked from the amplitude information of the class target;

[0010] S4. Calculate the change amount of the AGC control quantity according to the amplitude of the target to be tracked.

[0011] S5. Determine the gain adjustment amount according to the change amount of the AGC control quantity.

[0012] S6. Complete the AGC control according to the gain adjustment amount.

[0013] Furthermore, in S1, the radar parameters include the initial AGC activation threshold, the gain adjustment step, the gain control dead zone, the current cycle AGC gain control quantity, the next cycle AGC gain control quantity, the number of target scatter points, and the number of target types.

[0014] Furthermore, the method for determining the initial AGC activation threshold includes indoor signal source calibration and outdoor target calibration.

[0015] The indoor signal source calibration is specifically as follows: Obtain the radar echo signal in a darkroom. When the target amplitude of the radar echo signal displayed on the oscilloscope is in the nominal state, use the target intensity of the radar echo signal as the initial AGC activation threshold.

[0016] The nominal state is specifically the state when the target amplitude exceeds the clutter or the state when the target amplitude reaches half of the oscilloscope display range.

[0017] The outdoor target calibration is specifically as follows: Obtain the radar echo signal in the actual working environment. When the target amplitude of the radar echo signal displayed on the oscilloscope is in the nominal state, use the target intensity of the radar echo signal as the AGC activation threshold. The radar starts to work and is tested under this AGC activation threshold. Determine the initial AGC activation threshold according to the radar status data when the balance state is reached and the convergence speed meets the requirements.

[0018] The balance state is specifically that the radar reaches a state where the antenna does not shake or the shake is within a preset range under this AGC activation threshold.

[0019] The convergence speed meeting the requirements specifically means that the time required from activation to reaching the balance state meets the requirements.

[0020] Furthermore, in S1, determine the gain adjustment step and the gain control dead zone according to the target fluctuation characteristics and the target background clutter characteristics.

[0021] Furthermore, in S2, calculate the distance quantization unit difference and the Doppler quantization unit difference between every two scatter points in the target scatter point information set, and regard two scatter points with a distance quantization unit difference less than or equal to the distance threshold and a Doppler quantization unit difference less than or equal to the Doppler threshold as one class to complete the clustering.

[0022] Further, in S4, the calculation formula for the change amount ΔAGC of the AGC control amount is:

[0023] ΔAGC = T_AMP - Gate_AGC;

[0024] In the formula, T_AMP represents the amplitude of the target to be tracked, and Gate_AGC represents the initial threshold for AGC activation.

[0025] Further, in S5, the method for determining the gain adjustment amount is: If the change amount of the AGC control amount satisfies |ΔAGC| >= 4 * AGC_step, the calculation formula for the gain adjustment amount AGC_next is:

[0026]

[0027] In the formula, AGC_temp represents the AGC gain control amount in the current cycle, ΔAGC represents the change amount of the AGC control amount, int(·) represents the rounding function, and AGC_step represents the gain adjustment step;

[0028] If the change amount of the AGC control amount satisfies AGC_deadband < |ΔAGC| < 4 * AGC_step, the calculation formula for the gain adjustment amount AGC_next is:

[0029] AGC_next = AGC_temp + sign(ΔAGC)AGC_step;

[0030] In the formula, AGC_deadband represents the gain control dead zone, and sign(·) represents the sign function;

[0031] If the change amount of the AGC control amount satisfies |ΔAGC| ≤ AGC_step, the gain adjustment amount remains unchanged.

[0032] Further, in S6, if the gain adjustment amount is less than 0, the gain adjustment amount is set to 0, otherwise the gain adjustment amount remains unchanged.

[0033] The beneficial effects of the present invention are:

[0034] (1) The present invention is based on the amplitude of the radar-selected tracking target, rather than the amplitude envelope of the entire receiving channel, which can prevent the situation of large targets suppressing small targets or strong background clutter suppressing targets, such as the situation of sea surface ship targets, island shore backgrounds, or strong sea clutter backgrounds on the near side suppressing targets;

[0035] (2) The present invention sets a gain control dead zone, mainly for the situation where the target background clutter fluctuates greatly and is fast fluctuating, such as a sea ship target. The setting of the dead zone can instead stably control the output of the receiving channel, providing a more stable data source for signal processing and better analyzing the relevant information of the target;

[0036] (3) The present invention belongs to modular algorithm design and is directly embedded in the software system, with strong adaptability. It is applicable not only to newly developed radars but also to the technical upgrade of existing radars. Without modifying the hardware, it can effectively reduce the time and financial costs brought by performance upgrades. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flowchart of an adaptive digital AGC control method based on a target. DETAILED DESCRIPTION OF THE INVENTION

[0038] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0039] As Figure 1 shown, the present invention provides an adaptive digital AGC control method based on a target, including the following steps:

[0040] S1. Initialize the radar parameters, receive and analyze the echo data to obtain the target scatter point information set;

[0041] S2. Cluster the target scatter point information set according to the radar parameters and extract the amplitude information of the class target;

[0042] S3. Determine the amplitude of the target to be tracked from the amplitude information of the class target;

[0043] S4. Calculate the change amount of the AGC control quantity according to the amplitude of the target to be tracked;

[0044] S5. Determine the gain adjustment amount according to the change amount of the AGC control quantity;

[0045] S6. Complete the AGC control according to the gain adjustment amount.

[0046] In the embodiment of the present invention, in S1, the radar parameters include the initial AGC activation threshold, gain adjustment step, gain control dead zone, current cycle AGC gain control quantity, next cycle AGC gain control quantity, number of target scatter points, and number of target classes.

[0047] In the embodiment of the present invention, the method for determining the initial AGC activation threshold includes indoor signal source calibration and outdoor target calibration;

[0048] The indoor signal source calibration is specifically as follows: Obtain the radar echo signal in a darkroom. When the target amplitude of the radar echo signal displayed on the oscilloscope is in the nominal state, use the target intensity of the radar echo signal as the initial threshold for AGC activation;

[0049] The nominal state is specifically the state when the target amplitude exceeds the clutter or the state when the target amplitude reaches half of the display range of the oscilloscope;

[0050] The outdoor target calibration is specifically as follows: Obtain the radar echo signal in the actual working environment. When the target amplitude of the radar echo signal displayed on the oscilloscope is in the nominal state, use the target intensity of the radar echo signal as the AGC activation threshold. Under this AGC activation threshold, the radar starts to work and conducts tests. Determine the initial threshold for AGC activation based on the radar status data when it reaches the equilibrium state and the convergence speed meets the requirements;

[0051] The equilibrium state is specifically that the radar reaches a state where the antenna does not shake or the shake is within a preset range under this AGC activation threshold;

[0052] The convergence speed meeting the requirements specifically means that the time required from activation to reaching the equilibrium state meets the requirements.

[0053] For indoor signal source calibration, in a darkroom, according to the preset detection target characteristics and working environment of the radar, set the target RCS, noise or clutter (such as sea clutter, and the corresponding sea clutter intensity and fluctuation type can be set according to different sea states) and signal intensity on the simulation signal source to obtain the radar echo signal under this condition. Gradually increase the echo signal intensity from 0, and simultaneously observe the target amplitude and the target intensity analyzed by the radar on the oscilloscope and the radar display device. When the target amplitude displayed on the oscilloscope reaches the nominal state, record the target intensity analyzed by the radar at this time, which is the initial threshold for AGC activation. Here, the nominal state can be the state when the target amplitude just exceeds the clutter or the state when the target amplitude reaches half of the display range of the oscilloscope.

[0054] For outdoor target calibration, in the actual working environment such as on the sea surface, there are target ships at this time. Based on the activation threshold determined by indoor signal source calibration, vary the activation threshold within a certain range above and below and then conduct tests. Determine the optimal activation threshold value according to the stability of the test data and the convergence speed towards the equilibrium state.

[0055] In the embodiment of the present invention, in S1, determine the gain adjustment step and the gain control dead zone according to the target fluctuation characteristics and the target background clutter characteristics.

[0056] The gain adjustment step is generally not too large, and 1 dB or 2 dB can be taken. If the target + background clutter fluctuates greatly and is a fast fluctuation, such as the target being a sea ship, the dead zone can be taken a little larger because there is a time delay in the AGC control cycle, and overly precise control will instead prevent the system from reaching a stable state all the time; if the target + background clutter fluctuates little and is relatively stable, such as the target being a desert or forest object, the dead zone can be taken a little smaller.

[0057] In the embodiment of the present invention, in S2, calculate the distance quantization unit difference and Doppler quantization unit difference between every two scatter points in the target scatter point information set, and take two scatter points with the distance quantization unit difference less than or equal to the distance threshold and the Doppler quantization unit difference less than or equal to the Doppler threshold as one category to complete clustering.

[0058] The calculation of the AGC control amount is based on the amplitude of the radar-selected tracking target, rather than the amplitude envelope of the entire radar receiving channel, which can prevent the situation of large targets suppressing small targets or strong background clutter suppressing radar targets, such as the situation of sea ship targets, island shore backgrounds or strong sea clutter backgrounds on the near side suppressing targets.

[0059] Receive and parse the echo data to obtain the target scatter point information set, which is a set of multi-dimensional information, including information such as the target distance quantization unit, Doppler quantization unit, amplitude, and angle.

[0060] In the embodiment of the present invention, in S4, the calculation formula for the change amount ΔAGC of the AGC control amount is:

[0061] ΔAGC = T_AMP - Gate_AGC;

[0062] In the formula, T_AMP represents the amplitude of the target to be tracked, and Gate_AGC represents the initial threshold for the AGC to start.

[0063] In the embodiment of the present invention, in S5, the method for determining the gain adjustment amount is: if the change amount of the AGC control amount satisfies |ΔAGC| >= 4 * AGC_step, the calculation formula for the gain adjustment amount AGC_next is:

[0064]

[0065] In the formula, AGC_temp represents the AGC gain control amount in the current cycle, ΔAGC represents the change amount of the AGC control amount, int(·) represents the rounding function, and AGC_step represents the gain adjustment step;

[0066] If the change amount of the AGC control amount satisfies AGC_deadband < |ΔAGC| < 4 * AGC_step, the calculation formula for the gain adjustment amount AGC_next is:

[0067] AGC_next = AGC_temp + sign(ΔAGC) × AGC_step;

[0068] In the formula, AGC_deadband represents the gain control dead zone, and sign(·) represents the sign function;

[0069] If the change amount of the AGC control quantity satisfies |ΔAGC| ≤ AGC_step, the gain adjustment amount remains unchanged.

[0070] In the embodiment of the present invention, in S6, if the gain adjustment amount is less than 0, the gain adjustment amount is set to 0, otherwise the gain adjustment amount remains unchanged.

[0071] Those of ordinary skill in the art will realize that the embodiments described herein are to assist the reader in understanding the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations without departing from the essence of the present invention based on the technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the present invention.

Claims

1. A target-based adaptive digital AGC control method, characterized in that: The following steps are involved: S1, initialize radar parameters, receive and analyze echo data, and obtain target scattering point information set; S2. Cluster the target scattering point information set according to radar parameters and extract the amplitude information of the target class; S3, determining the amplitude of the target to be tracked from the amplitude information of the class target; S4. Calculate the change of the AGC control amount according to the target amplitude to be tracked; S5. Determine the gain adjustment amount according to the change in the AGC control amount; S6. Complete AGC control according to the gain adjustment amount.

2. The target-based adaptive digital AGC control method according to claim 1, characterized in that: In S1, the radar parameters include AGC control initial threshold, gain adjustment step, gain control dead zone, current cycle AGC gain control amount, next cycle AGC gain control amount, number of target scattering points and number of target types.

3. The target-based adaptive digital AGC control method according to claim 2, characterized in that: The method for determining the initial threshold of the AGC control includes indoor signal source calibration and outdoor target calibration; The indoor signal source calibration is specifically as follows: obtaining a radar echo signal in a dark room, and when the target amplitude of the radar echo signal displayed on the oscilloscope is in a nominal state, using the target intensity of the radar echo signal as the initial threshold for AGC control; The nominal state is specifically a state when the target amplitude exceeds the clutter or a state when the target amplitude reaches half of the display range of the oscilloscope; The field target calibration is specifically as follows: a radar echo signal is acquired in a real working environment; when the target amplitude displayed by the radar echo signal on the oscilloscope is in a nominal state, the target intensity of the radar echo signal is used as the AGC control threshold; the radar starts working and is tested under the AGC control threshold; and according to the radar state data, it is judged that a balanced state is reached and the convergence speed meets the requirements, and the AGC control initial threshold is determined; The equilibrium state specifically refers to that the radar antenna does not vibrate or vibrates within a preset range under the AGC control threshold; The convergence speed satisfies the requirement specifically that the time required from starting control to reaching a balanced state satisfies the requirement.

4. The target-based adaptive digital AGC control method according to claim 2, characterized in that: In S1, the gain adjustment step and the gain control dead zone are determined according to the target fluctuation characteristics and the target background clutter characteristics.

5. The target-based adaptive digital AGC control method according to claim 1, characterized in that: In S2, the distance quantization unit difference and the Doppler quantization unit difference between every two scattering points in the target scattering point information set are calculated, and two scattering points whose distance quantization unit difference is less than or equal to the distance threshold and whose Doppler quantization unit difference is less than or equal to the Doppler threshold are taken as one class to complete clustering.

6. The target-based adaptive digital AGC control method according to claim 1, characterized in that: In S4, the calculation formula of the change amount ΔAGC of the AGC control amount is: ΔAGC = T_AMP - Gate_AGC; Where T_AMP is the target amplitude to be tracked, and Gate_AGC is the initial threshold for AGC control.

7. The target-based adaptive digital AGC control method according to claim 1, characterized in that: In S5, the method for determining the gain adjustment amount is: if the change in the AGC control amount satisfies |ΔAGC|>=4*AGC_step, the calculation formula of the gain adjustment amount AGC_next is: Where AGC_temp represents the AGC gain control value of the current cycle, ΔAGC represents the change of the AGC control value, int(·) represents the rounding function, and AGC_step represents the gain adjustment step; If the change in the AGC control amount satisfies AGC_deadband<|ΔAGC|<4*AGC_step, the calculation formula for the gain adjustment amount AGC_next is: AGC_next=AGC_temp+sign(ΔAGC)AGC_step; Where AGC_deadband represents the gain control dead band, sign(·) represents the sign function; If the change in the AGC control amount satisfies |ΔAGC|≤AGC_step, the gain adjustment amount remains unchanged.

8. The target-based adaptive digital AGC control method according to claim 1, characterized in that: In S6, if the gain adjustment amount is less than 0, the gain adjustment amount is set to 0, otherwise the gain adjustment amount remains unchanged.

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