A target-based adaptive digital agc control method

Abstract

The application discloses a target-based adaptive digital AGC control method and belongs to the technical field of radar control, and comprises the following steps: S1, initializing radar parameters, receiving and analyzing echo data to obtain a target scattering point information set; S2, clustering the target scattering point information set according to the radar parameters and extracting amplitude information of a class target; S3, determining a to-be-tracked target amplitude from the amplitude information of the class target; S4, calculating a change amount of an AGC control amount according to the to-be-tracked target amplitude; S5, determining a gain adjustment amount according to the change amount of the AGC control amount; and S6, completing AGC control according to the gain adjustment amount. The amplitude of a selected tracking target of the radar is taken as a reference instead of the amplitude envelope of the whole receiving channel, so that the situation that a large target suppresses a small target or a strong background clutter suppresses a target can be prevented.

Description

Technical Field

[0001] This invention belongs to the field of radar control technology, specifically relating to a target-based adaptive digital AGC control method. Background Technology

[0002] The automatic gain control (AGC) circuit is an important component of radar. Its function is to automatically adjust the radar receiver gain according to the strength of the signal in the receiving channel. When the received target signal is weak, the receiver has high gain to ensure the detection of distant or small targets; when the received signal is strong, the receiver has low gain to ensure the detection of nearby targets. Through AGC control, the signal output by the receiver is always kept stable within an appropriate range, regardless of the distance of the detected target or the size of the target's RCS.

[0003] However, existing radar automatic gain control (AGC) circuits all rely on the entire signal envelope of the receiving channel for gain control. This has a limitation: when a target, such as a ship, passes over an island or port background, or is leaving / entering the port, the background clutter is very strong, submerging the target signal and resulting in a very strong signal (clutter + target) across the entire receiving channel. If the traditional method is used, with the strongest value of the entire receiving channel's signal envelope as the reference for AGC control, the receiving channel gain will become extremely low, leading to strong clutter overwhelming the target signal and directly preventing effective target detection. Furthermore, if both large and small targets are present simultaneously, such as ships passing over a signal tower or ships of different sizes converging, using the traditional method with the strongest value of the entire receiving channel's signal envelope as the reference for AGC control means the receiving channel gain is determined based on the larger target, potentially causing the larger target to overwhelm the smaller target and affecting its effective detection.

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

[0005] To address the problems of poor anti-interference capability against nearby targets, ineffective target detection in strong clutter backgrounds, and ineffective detection of small targets when large and small targets intersect, this invention proposes a target-based adaptive digital AGC control method.

[0006] The technical solution of this invention is: a target-based adaptive digital AGC control method comprising the following steps:

[0007] S1. Initialize radar parameters, receive and parse echo data to obtain target scattering point information set;

[0008] S2. Based on the radar parameters, cluster the target scattering point information set and extract the amplitude information of the target groups;

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

[0010] S4. Calculate the change in AGC control quantity based on the amplitude of the target to be tracked;

[0011] S5. Determine the gain adjustment amount based on the change in the AGC control quantity;

[0012] S6. Complete AGC control based on the gain adjustment amount.

[0013] Furthermore, in S1, the radar parameters include the AGC 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.

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

[0015] The indoor signal source calibration is as follows: acquire radar echo signals in an anechoic chamber, and when the target amplitude of the radar echo signal displayed on the oscilloscope is at the nominal state, use the target intensity of the radar echo signal as the initial threshold for AGC control.

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

[0017] The specific field target calibration is as follows: acquire radar echo signals in the real working environment. When the target amplitude displayed on the oscilloscope is at the nominal state, use the target intensity of the radar echo signal as the AGC start-up threshold. Under this AGC start-up threshold, the radar starts working and is tested. Based on the radar status data, it is determined that the equilibrium state has been reached and the convergence speed meets the requirements. The initial threshold for AGC start-up is then determined.

[0018] The equilibrium state is specifically defined as the radar antenna not jittering or jittering within a preset range under the AGC start-up threshold.

[0019] The convergence speed meets the requirement, specifically the time required from the start of control to reaching the equilibrium state.

[0020] Furthermore, in S1, the gain adjustment step and gain control dead zone are determined based on the target fluctuation characteristics and the target background clutter characteristics.

[0021] Furthermore, in S2, the distance quantization unit difference and 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 grouped together to complete the clustering.

[0022] Furthermore, in S4, the formula for calculating the change in the AGC control quantity ΔAGC 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 control.

[0025] Furthermore, in S5, the method for determining the gain adjustment amount is as follows: if the change in the AGC control quantity satisfies |ΔAGC|>=4*AGC_step, then the formula for calculating 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 in the AGC control amount, int(·) represents the floor function, and AGC_step represents the gain adjustment step.

[0028] If the change in the AGC control quantity satisfies AGC_deadband < |ΔAGC| < 4 * AGC_step, then the formula for calculating the gain adjustment 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 in the AGC control quantity satisfies |ΔAGC|≤AGC_step, then the gain adjustment remains unchanged.

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

[0033] The beneficial effects of this invention are:

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

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

[0036] (3) This invention belongs to modular algorithm design, which is directly embedded in the software system. It is highly adaptable and applicable not only to newly developed radars, but also to the technical upgrade of existing radars. No hardware modifications are required, which can effectively reduce the time and financial expenses brought about by performance upgrades. Attached Figure Description

[0037] Figure 1 This is a flowchart of a goal-based adaptive digital AGC control method. Detailed Implementation

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

[0039] like Figure 1 As shown, this invention provides a target-based adaptive digital AGC control method, comprising the following steps:

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

[0041] S2. Based on the radar parameters, cluster the target scattering point information set and extract the amplitude information of the target groups;

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

[0043] S4. Calculate the change in AGC control quantity based on the amplitude of the target to be tracked;

[0044] S5. Determine the gain adjustment amount based on the change in the AGC control quantity;

[0045] S6. Complete AGC control based on the gain adjustment amount.

[0046] In this embodiment of the invention, S1 includes radar parameters such as AGC 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.

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

[0048] The indoor signal source calibration is as follows: acquire radar echo signals in an anechoic chamber, and when the target amplitude of the radar echo signal displayed on the oscilloscope is at the nominal state, use the target intensity of the radar echo signal as the initial threshold for AGC control.

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

[0050] The specific field target calibration is as follows: acquire radar echo signals in the real working environment. When the target amplitude displayed on the oscilloscope is at the nominal state, use the target intensity of the radar echo signal as the AGC start-up threshold. Under this AGC start-up threshold, the radar starts working and is tested. Based on the radar status data, it is determined that the equilibrium state has been reached and the convergence speed meets the requirements. The initial threshold for AGC start-up is then determined.

[0051] The equilibrium state is specifically defined as the radar antenna not jittering or jittering within a preset range under the AGC start-up threshold.

[0052] The convergence speed meets the requirement, specifically the time required from the start of control to reaching the equilibrium state.

[0053] For indoor signal source calibration, in an anechoic chamber, based on the radar's preset target characteristics and operating environment, the target RCS, noise or clutter (such as sea clutter, the intensity and fluctuation type of which can be set according to different sea conditions), and signal strength are set on the simulated signal source to obtain the radar echo signal under these conditions. The echo signal strength is gradually increased from 0, and the target amplitude and radar-resolved target intensity are simultaneously observed on an oscilloscope and radar display device. When the target amplitude displayed on the oscilloscope reaches the nominal state, the radar-resolved target intensity at this point is recorded; this is the initial threshold for AGC (Automatic Gauge Control) activation. The nominal state can be either the state where the target amplitude just exceeds the clutter threshold, or the state where the target amplitude reaches half the oscilloscope display range.

[0054] For field target calibration, in a real working environment such as the sea, there is a target vessel. Based on the control threshold determined by the indoor signal source calibration, the control threshold is varied within a certain positive and negative range and then tested. The optimal control threshold value is determined based on the stability of the test data and the convergence speed towards the equilibrium state.

[0055] In this embodiment of the invention, in S1, the gain adjustment step and gain control dead zone are determined based on the target fluctuation characteristics and the target background clutter characteristics.

[0056] Gain adjustment steps should generally not be too large, and can be set to 1dB or 2dB. If the target + background clutter fluctuations are large and fast, such as if the target is a ship on the sea, the dead zone can be set slightly larger, because AGC control has a certain periodic time delay, and overly precise control will prevent the system from reaching a stable state. If the target + background clutter fluctuations are small and relatively stable, such as if the target is a desert or forest object, the dead zone can be set slightly smaller.

[0057] In this embodiment of the invention, in S2, the distance quantization unit difference and 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 classified as a group to complete clustering.

[0058] The AGC control quantity calculation is based on the amplitude of the radar-selected target, rather than the amplitude envelope of the entire radar receiving channel. This can prevent situations where large targets suppress small targets, or strong background clutter suppresses radar targets, such as ship targets on the sea surface, island and shore backgrounds, or strong sea clutter backgrounds on the near side suppressing targets.

[0059] The system receives and parses echo data to obtain a set of target scattering point information, which is a collection of multi-dimensional information, including target range quantization units, Doppler quantization units, amplitude, and angle information.

[0060] In this embodiment of the invention, the formula for calculating the change in AGC control quantity ΔAGC in S4 is as follows:

[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 AGC control.

[0063] In this embodiment of the invention, in S5, the method for determining the gain adjustment amount is as follows: if the change in the AGC control amount satisfies |ΔAGC|>=4*AGC_step, then 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 in the AGC control amount, int(·) represents the floor function, and AGC_step represents the gain adjustment step.

[0066] If the change in the AGC control quantity satisfies AGC_deadband < |ΔAGC| < 4 * AGC_step, then the formula for calculating the gain adjustment 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 in the AGC control quantity satisfies |ΔAGC|≤AGC_step, then the gain adjustment remains unchanged.

[0070] In this embodiment of the invention, in step 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 skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A goal-based adaptive digital AGC control method, characterized in that, Includes the following steps: S1. Initialize radar parameters, receive and parse echo data to obtain target scattering point information set; S2. Based on the radar parameters, cluster the target scattering point information set and extract the amplitude information of the target groups; S3. Determine the amplitude of the target to be tracked from the amplitude information of the target class; S4. Calculate the change in AGC control quantity based on the amplitude of the target to be tracked; S5. Determine the gain adjustment amount based on the change in the AGC control quantity; S6. Complete AGC control based on the gain adjustment amount; In step S2, the distance quantization unit difference and 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 classified as a group to complete the clustering. In S4, the change in the AGC control quantity The calculation formula is: ； In the formula, Indicates the magnitude of the target to be tracked. Indicates the initial threshold for AGC control; In step S5, the method for determining the gain adjustment amount is as follows: if the change in the AGC control amount satisfies... Then the gain adjustment amount The calculation formula is: ； In the formula, This indicates the AGC gain control value for the current cycle. This indicates the change in the AGC control quantity. This represents the floor function. Indicates the gain adjustment step; If the change in the AGC control quantity satisfies Then the gain adjustment amount The calculation formula is: ； In the formula, Indicates the gain control dead zone. Represents a symbolic function; If the change in the AGC control quantity satisfies If the gain adjustment remains unchanged, then the gain adjustment amount remains unchanged.

2. The target-based adaptive digital AGC control method according to claim 1, characterized in that, In S1, the radar parameters include the AGC 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 AGC control includes indoor signal source calibration and outdoor target calibration; The indoor signal source calibration is specifically as follows: acquire radar echo signals in an anechoic chamber, and when the target amplitude of the radar echo signal displayed on the oscilloscope is at the nominal state, use the target intensity of the radar echo signal as the initial threshold for AGC control. The nominal state is specifically the state when the target amplitude exceeds the noise or the state when the target amplitude reaches half of the oscilloscope display range. The field target calibration is specifically as follows: acquire radar echo signals in a real working environment, and when the target amplitude displayed on the oscilloscope is at the nominal state, use the target intensity of the radar echo signal as the AGC start-up threshold. Under this AGC start-up threshold, the radar starts working and is tested. Based on the radar status data, it is determined that the equilibrium state has been reached and the convergence speed meets the requirements, and the initial threshold for AGC start-up is determined. The equilibrium state is specifically defined as the radar antenna not jittering or jittering within a preset range under the AGC start-up threshold. The convergence speed requirement specifically refers to the time required from the start of control to reaching the equilibrium state meeting the requirements.

4. The target-based adaptive digital AGC control method according to claim 2, characterized in that, In S1, the gain adjustment step and gain control dead zone are determined based on 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 step S6, if the gain adjustment is less than 0, the gain adjustment is set to 0; otherwise, the gain adjustment remains unchanged.

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