A method for designing a sensitivity time control curve of a sea clutter suppression radar receiver

Abstract

The present application relates to a kind of sea clutter suppression radar receiver sensitivity time control curve design method, for the radar to the sea clutter suppression when commonly used radar receiver sensitivity time (STC) control curve is improved design, traditional STC control curve with distance variation is improved as the STC control curve with sea state variation, satisfy the change requirement of radar receiver to sea clutter suppression depth under different sea conditions.The present application compared with prior art, its obvious advantages are: the sea clutter scattering intensity under different sea conditions is analyzed specifically, and the STC control curve that can effectively deal with under different sea conditions is designed, satisfy the requirement of radar fine sea clutter suppression (avoid excessive suppression) under different sea conditions.The present application can realize the control requirement of radar under different sea conditions by changing the original radar STC control curve parameter, without changing the original radar hardware configuration, convenient and fast.

Description

Technical Field

[0001] This invention belongs to the field of radar receiver technology and relates to a method for designing the sensitivity time control curve of a radar receiver to suppress sea clutter. It is a design of a radar receiver sensitivity time (STC) control curve to cope with the interference of sea clutter on radar operation when the radar is detecting on the sea surface. Background Technology

[0002] Gain control in radar receivers primarily includes Sensitivity Time Control (STC) and Automatic Gain Control (AGC). STC, also known as short-range gain control, is used to prevent receiver overload saturation caused by short-range interference. In practical operation, radar inevitably suffers from interference reflected by nearby sea clutter. Previously, radar STC curves were designed based on the assumption that the interference power reflected by these clutter objects was relatively constant in azimuth and decreased relatively smoothly with increasing distance, often resulting in a distance-dependent control curve. However, with varying sea states, users often only increase the control distance when adjusting STC, with little change in gain control at the same distance. This effectively turns it into a sea clutter suppression switch—effective or ineffective. Even when effective, it doesn't differentiate between sea states, often leading to over-suppression and suppressing the desired target.

[0003] This method proposes a new sensitivity time control curve for sea clutter suppression radar receivers. This curve varies with the sea state, thus enabling sea clutter suppression for shipborne radars under different sea conditions. After on-site testing at sea, its performance is superior to the traditional STC curve. Summary of the Invention

[0004] Technical problems to be solved

[0005] To avoid the shortcomings of existing technologies, this invention proposes a method for designing the sensitivity time control curve of a sea clutter suppression radar receiver, which can improve the radar's ability to suppress clutter interference under different sea conditions.

[0006] Technical solution

[0007] A method for designing the sensitivity time control curve of a sea clutter suppression radar receiver, characterized by the following steps:

[0008] Step 1: Calculate the radar scattering intensity of sea clutter under different sea conditions according to the sea clutter scattering calculation formula, and obtain the RCS curve of sea clutter radar scattering intensity.

[0009] Step 2: Based on the radar scattering intensity of sea clutter under different sea states, design the STC control curve that varies with sea state. The steps are as follows:

[0010] Step 2a: Calculate the maximum STC control range x required for this radar based on the highest sea state clutter scattering intensity that the radar needs to suppress. max ;

[0011] Step 2b: Calculate the curve control adjustment coefficient based on sea state intensity to meet the sea clutter intensity suppression requirements under different sea states; B = a × x max Where: a is the radar gain adjustment coefficient, x max This is the designed maximum control range of the radar;

[0012] Step 2c: Based on the above constraints, obtain the STC control parameter value Y:

[0013] y = 40·log(x+B) - 40·logx max

[0014] Where x is the distance, y is the control parameter value, and B is the control coefficient under different sea states;

[0015] With the horizontal axis representing the radar distance and the vertical axis representing the STC control parameter value Y, by changing the adjustment coefficient of the radar gain, the control parameter value Y at different distances x is obtained, thus obtaining the STC control curve that varies with sea state.

[0016] The calculation of sea clutter radar scattering intensity under different sea states in step 1 is as follows:

[0017] The main lobe clutter region is: σ MBc =σ 0 ΔRcosθ r ·Rcosθ r ·θ 3dB

[0018] θ r Radar ground scouring angle: θ r =arcsin(h r / R);

[0019] ΔR represents the radar range resolution;

[0020] h r To elevate the radar antenna;

[0021] σ 0 The scattering coefficients of sea clutter under different sea states;

[0022] θ 3dB This refers to the horizontal beamwidth of the radar.

[0023] The radar range resolution ΔR is set to 20m.

[0024] The radar antenna frame is at a height of h. r It is 3 meters high.

[0025] The different sea states refer to the sea clutter scattering coefficient σ under sea state level 4. 0 Take -30dB.

[0026] The different sea states refer to the sea clutter scattering coefficient σ under sea state level 6. 0 Take -15dB.

[0027] The radar horizontal beamwidth θ 3dB It is 4°.

[0028] Step 2a involves calculating the radar's sea clutter detection range under different sea states based on the radar equations, and multiplying the radar's sea clutter detection range by a coefficient to obtain the maximum STC control range x. max .

[0029] The coefficient is 1-3.

[0030] An application of an STC control curve designed using the aforementioned design method is characterized in that: the STC control curve is used in a radar receiver controllable attenuator to attenuate the energy of the radar-received echo signal over time.

[0031] Beneficial effects

[0032] This invention proposes a method for designing the sensitivity time control curve of a radar receiver for suppressing sea clutter. It improves the commonly used radar receiver sensitivity time (STC) control curve for suppressing sea clutter by changing the traditional STC control curve that varies with distance to an STC control curve that varies with sea state, thus meeting the varying requirements of the radar receiver for suppressing sea clutter depth under different sea states.

[0033] Compared with the prior art, the significant advantages of this invention are: it specifically analyzes the clutter scattering intensity under different sea conditions, designs STC control curves that can effectively cope with different sea conditions, and meets the radar's need for fine-grained suppression of sea clutter under different sea conditions (avoiding over-suppression).

[0034] The technical solution of this invention improves upon existing navigation radar by changing the STC control curve parameters of the original radar, thereby achieving the radar's control requirements under different sea conditions without altering the original radar hardware configuration, making it convenient and quick.

[0035] The STC control curve is an amplitude control curve that varies with distance. Designing this curve involves: first, determining the maximum control distance x. max Secondly, there is the control value Y of the curve. Since the impact of sea clutter on radar detection decreases with increasing distance, the maximum control range x... max The clutter scattering intensity under different sea states should be considered, and the clutter scattering intensity under different sea states should be used as the basis for calculating the maximum STC control range x required for this radar.max When calculating the STC control parameter Y value, the design curve formula is y = 40·log(x+B) - 40·logx. max The maximum STC control distance x was considered again. max The influence of this, and the adjustment coefficient B = a × x in the formula. max The maximum STC control distance x was also taken into account. max Influencing factors. Attached Figure Description

[0036] Figure 1 This is the main flowchart for the design of the sensitivity time control curve of a radar receiver for suppressing sea clutter, as described in this invention.

[0037] Figure 2 Sea clutter scattering intensity under sea states 4 and 6:

[0038] a: Sea clutter scattering intensity under sea state 4;

[0039] b: Sea clutter scattering intensity under sea state 6

[0040] Figure 3 Analysis of the maximum clutter detection range of a certain radar under different sea states:

[0041] Figure 3 Explanation: In graphs a and b, the horizontal axis represents distance, and the vertical axis represents the energy intensity ratio. The purple horizontal line in the graphs represents the minimum energy intensity ratio required for radar to detect the echo. This invention aims to suppress detectable sea clutter. Therefore, observing the CNR (clutter-to-noise energy ratio), it can be seen that under different sea conditions, the distance where the CNR value is greater than the purple horizontal line is within 1 km. Therefore, the radar can detect sea clutter within a 1 km range. However, considering the accuracy of the theoretical model and appropriate scaling design criteria, x max The radar is designed to have a maximum control range of 3km.

[0042] Figure 4 STC control curves for different sea states: Figure 4 The STC control curves correspond to different control parameters. Different suppression curves can be selected according to the sea state. The horizontal axis represents the maximum control distance, and the vertical axis represents the STC curve suppression depth.

[0043] a: When STC = 1, a = 3;

[0044] b: When STC = 2, a = 1.3

[0045] c: When STC = 3, a = 0.7

[0046] d: When STC = 4, a = 0.45

[0047] e: When STC = 5, a = 0.3

[0048] f: When STC = 6, a = 0.2. Detailed Implementation

[0049] The present invention will now be further described in conjunction with the embodiments and accompanying drawings:

[0050] like Figure 1 As shown, the present invention provides a design for the sensitivity time control curve of a sea clutter suppression radar receiver, comprising the following steps:

[0051] 1) Simulation of sea clutter radar scattering intensity: Based on the sea clutter scattering calculation formula, calculate the sea clutter radar scattering intensity under different sea conditions, and design STC curves for different sea conditions based on the scattering intensity;

[0052] The formula for calculating the RCS of sea clutter within the region is as follows:

[0053] The main lobe clutter region is: σ MBc =σ 0 ΔRcosθ r ·Rcosθ r ·θ 3dB

[0054] θ r Radar ground scouring angle: θ r =arcsin(h r / R);

[0055] ΔR is the radar range resolution, which is 20m for this radar.

[0056] h r To ensure the radar antenna is mounted at a height of 3 meters, this radar is designed to be mounted at a height of 3 meters.

[0057] σ 0 The sea clutter scattering coefficients under different sea states are calculated as follows: for a smaller grazing angle, the coefficients are -30 dB for sea state 4 and -15 dB for sea state 6.

[0058] θ 3dB The horizontal beamwidth of this radar is 4°.

[0059] Based on the above formula, radar cross-section (RCS) curves of sea clutter under sea states 4 and 6 are given, as follows: Figure 2 As shown. The RCS value of sea clutter at 1m 2 the following.

[0060] 2) STC control curve design: Based on the radar scattering intensity of sea clutter under different sea states, a new STC control curve that varies with sea state is designed.

[0061] 21) Determine the maximum STC control range: Calculate and determine the maximum STC control range required for this radar based on the highest sea state clutter scattering intensity that the radar needs to suppress;

[0062] The calculation of the maximum STC control range x required for this radar is described. max Related to the minimum detectable clutter ratio (CNR) of the radar, the radar's sea clutter detection range under different sea states is calculated based on the radar equation. Considering the principle of appropriate amplification, a coefficient (selected between 1 and 3 based on actual test results) is multiplied to obtain the maximum STC control range x. max .

[0063] Radar parameters: X-band, transmit power 80W, beamwidth 4 degrees, pulse width 0.1µs. The detection range of this radar for sea clutter under different sea states is as follows: Figure 3 As shown. The radar detection range is within 1 km.

[0064] 22) Design adjustment coefficient: Based on the sea state intensity, design the curve control adjustment coefficient to meet the sea clutter intensity suppression requirements under different sea states;

[0065] Design B = a × x max 'a' is the adjustment coefficient, and 'x' is the adjustment coefficient. max It is the designed maximum control range of the radar.

[0066] 23) STC control curve: Based on the above constraints, design the mathematical formula for the STC control curve to form the STC control parameters.

[0067] The mathematical formula for designing the STC control curve is as follows:

[0068] y = 40·log(x+B) - 40·logx max (1)

[0069] Where x is the distance, y is the control parameter value, and B is the control coefficient for different sea states.

[0070] STC curves under different control coefficients are as follows Figure 4 As shown.

[0071] This led to the design of a sensitivity time control curve for a sea clutter suppression radar receiver, meeting the radar's gain control requirements under different sea conditions.

[0072] The technical solution of this invention allows for STC curve design on existing radars. Without changing the original radar hardware configuration, it specifically analyzes the clutter scattering intensity under different sea conditions and designs an STC control curve that can effectively cope with different sea conditions, thus meeting the radar's need for refined suppression of sea clutter under different sea conditions (avoiding over-suppression).

Claims

1. A method of designing a sensitivity time control curve for a sea clutter mitigation radar receiver, characterized in that The steps are as follows: Step 1: Calculate the radar scattering intensity of sea clutter under different sea conditions according to the sea clutter scattering calculation formula, and obtain the RCS curve of sea clutter radar scattering intensity. Step 2: Based on the radar scattering intensity of sea clutter under different sea states, design the STC control curve that varies with sea state. The steps are as follows: Step 2a: Calculate the maximum STC control range required for this radar based on the highest sea state sea clutter scattering intensity that the radar needs to suppress ; Step 2b: According to the sea state intensity, the curve control adjustment coefficient is calculated to meet the sea clutter intensity suppression requirements under different sea states; , wherein: a is the adjustment coefficient of radar gain, is the designed maximum control distance of the radar; Step 2c: Obtain STC control parameter values according to the above constraints y Value: wherein x is the distance, y control parameter value, B is the control coefficient under different sea conditions; The horizontal axis is the radar range, and the vertical axis is the STC control parameter value y The adjustment coefficient of the radar gain is changed to obtain different distances x The control parameter value Y The STC control curve changes with the sea state.

2. The method of claim 1, wherein: The calculation of sea clutter radar scattering intensity under different sea states in step 1 is as follows: The main-lobe spur region is: For radar ground clearance: ; For radar range resolution; h r To elevate the radar antenna; For different sea conditions, according to statistics, when the smaller ground angle is-30dB, 6 sea conditions-15dB; The horizontal beamwidth of this radar is 4°.

3. The method for designing the sensitivity time control curve of a sea clutter suppression radar receiver according to claim 2, characterized in that: The radar range resolution The value is 20m.

4. The method for designing the sensitivity time control curve of a sea clutter suppression radar receiver according to claim 2, characterized in that: The radar antenna height h r is 3 m height.

5. The method for designing the sensitivity time control curve of a sea clutter suppression radar receiver according to claim 2, characterized in that: The different sea states refer to the sea clutter scattering coefficients under sea state level 4. Take -30dB.

6. The method for designing the sensitivity time control curve of a sea clutter suppression radar receiver according to claim 2, characterized in that: The different sea states refer to the sea clutter scattering coefficients under sea state level 6. Take -15dB.

7. The method for designing the sensitivity time control curve of a sea clutter suppression radar receiver according to claim 2, characterized in that: The radar horizontal beamwidth It is 4°.

8. The method for designing the sensitivity time control curve of a sea clutter suppression radar receiver according to claim 1, characterized in that: Step 2a involves calculating the radar's sea clutter detection range under different sea states based on the radar equations, and then multiplying the radar's sea clutter detection range by a coefficient to obtain the maximum STC control range. .

9. The method for designing the sensitivity time control curve of a sea clutter suppression radar receiver according to claim 8, characterized in that: The coefficient is 1-3.

10. An application method for an STC control curve designed using the design method described in any one of claims 1 to 9, characterized in that: The STC control curve is used in radar receiver controllable attenuators to attenuate the energy of the radar echo signal over time.

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