Method for adaptive power management of an active phased array radar

Abstract

The method for adaptive power management of the active phased array radar of the application comprises: acquiring guidance information of the current radar in a search state and a tracking state; the guidance information comprises guidance information of avionics in the search state and detection information of the radar on a target in the tracking state; calculating a critical detection distance of the radar according to the guidance information, and preliminarily determining the number M of array elements to be turned off; determining a pattern of the array elements to be turned off on the array surface according to the number M of the array elements to be turned off, wherein the pattern of the array elements to be turned off is determined according to a symmetric equal circle method; and evaluating and optimizing the pattern of the array elements to be turned off. The optimal matching of radiation power control and detection performance is realized, and the detection performance loss of the radar is reduced as much as possible.

Description

Technical Field

[0001] This invention belongs to the field of airborne fire control radar, and particularly relates to a method for adaptive power management of active phased array radar. Background Technology

[0002] With the development of radar electronic countermeasures technology and the emergence of anti-radiation missiles, modern radar systems face increasingly harsh working and survival environments. Reducing the probability of radar signals being detected and intercepted has become a hot research topic in radar detection technology. Low Probability of Interception (LPI), also known as radio frequency stealth, is an important stealth measure for aircraft. The exploration of LPI theory began in the 1970s, and in 1983, J.R.Forest of the University of London first introduced the LPI radar equation. LPI radar can be qualitatively understood as "minimizing the probability that the enemy will intercept the radar signal while the radar detects the enemy target." For airborne radar, this means controlling the radar signal, reducing radar wave radiation, or increasing signal complexity to lower the possibility of detection by passive detection devices. That is, radiated power is both transmitted and received, with a longer transmission time. Traditionally, controlling the radar radiation time to be long makes it easier to detect, and reducing the probability of radar detection or target detection leads to a decrease in radar performance.

[0003] In view of this, the present invention is hereby proposed. Summary of the Invention

[0004] The purpose of this invention is to provide an adaptive power management method for active phased array radar, solving the technical problem that existing methods reduce radar performance. The technical solution of this invention has many beneficial effects, as described below:

[0005] An adaptive power management method for an active phased array radar is provided, enabling the radar to detect targets in complex and variable environments. The method includes:

[0006] The system acquires guidance information for the current radar target search and tracking states. The guidance information includes avionics guidance information and radar target detection information. The radar target detection information includes at least the target range, signal-to-noise ratio, and health time. The avionics guidance information is information sent to the radar by the aircraft's avionics system.

[0007] In the search state, when the radar acquires the avionics guidance information, it calculates the critical detection range in the search state based on the guidance information and preliminarily determines the number M of array elements that need to be turned off in the search state.

[0008] In target tracking mode, the radar optimizes the number M of array elements that need to be shut down as determined in search mode. It then uses the difference between the signal-to-noise ratio and the radar detection threshold as a redundancy to evaluate the health time. Finally, it comprehensively optimizes and calculates the critical detection range R in tracking mode based on the redundancy and the evaluation results. c To initially determine the number of array elements that need to be turned off in tracking mode;

[0009] Based on the number of array elements that need to be turned off under the tracking state, the pattern of the array elements to be turned off is determined on the array surface. The pattern of the array elements to be turned off is determined according to the symmetrical equal circle method.

[0010] The pattern of the array element to be shut down is evaluated, the array element pattern is converted into an antenna pattern, the position of the grating lobe in the antenna pattern is determined, and then the pattern of the shut-down array element with the least impact on radar performance is determined.

[0011] The optimization process determines the final number of array elements to be shut down.

[0012] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0013] Its key feature lies in its ability to dynamically adjust the radar's radiated power by precisely switching the radar's radiating elements, based on the target echo signal-to-noise ratio and health time, without altering the radar's equivalent aperture. This enhances the radar's low-intercept performance. Compared to existing power management methods (such as adjusting duty cycle and accumulation time), element-level power management achieves optimal matching between radiated power control and detection performance, minimizing radar detection performance loss. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 Flowchart for radar radiated power management;

[0016] Figure 2 A graph showing the relationship between detection distance and the proportion of closed array elements;

[0017] Figure 3 Linear array and its radiation pattern;

[0018] Figure 4 To disable a portion of the linear array elements and their radiation patterns;

[0019] Figure 5A circular array and its orientation diagram;

[0020] Figure 6 A circular array and its radiation pattern with some array elements turned off while the radar is in target tracking mode;

[0021] Figure 7 A circular array and its radiation pattern with some array elements turned off while the radar is in search mode;

[0022] Figure 8 The ratio of main lobe to sidelobe in the radiation pattern varies with the proportion of antenna elements that are turned off. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Radar countermeasures against intercepting receivers can generally be approached from several aspects, including the time domain, power domain, spectrum domain, spatial domain, and waveform modulation domain. The ultimate goal is to distribute the power of the radar transmitted signal as much as possible in the time, frequency, and spatial domains, making it difficult for the intercepting receiver to acquire radar information, while not affecting the radar's reception of the echo signal formed after the transmitted signal power is reflected by the target.

[0025] In the time domain, controlling the timing and duration of radar radiation, employing methods such as burst detection, random detection, and increasing the detection time interval, can minimize the probability of being detected by the enemy. In the frequency domain, transmitting ultra-wide spectrum instead of narrow spectrum can reduce the spectral power density of the transmitted signal. In the spatial domain, adaptive pattern technology, radiation space management technology, and wide-beam low-gain transmission technology can be used to reduce the electromagnetic wave space density in the direction of the reconnaissance receiver. In addition, complex waveform modulation techniques, the addition of induced signals, and simultaneous use of multiple carrier frequencies can be employed to increase the difficulty of sorting and identifying radar signals.

[0026] From a power domain perspective, the interception capability of a radar receiver is determined by the power density of the radar signal reaching the receiver antenna, i.e., the signal power per unit area. Therefore, a more accurate definition of controlling radar transmit power is controlling the power-aperture product of radar transmission. Specific methods include controlling duty cycle, accumulation time, radiated power, and burst detection. For radiated power control, a method of array shrinking can be used, i.e., switching radiating elements according to a symmetrical strategy. Alternatively, a desaturation method can be used to make the T / R module operate in the linear region, linearly controlling its output power. This invention uses the equal-circle method for element-level power switching control and optimizes the radiating element pattern by evaluating angular measurement accuracy and grating lobe position, achieving optimal matching between radiated power control and detection performance, and minimizing radar detection performance loss.

[0027] The adaptive power management method for active phased array radar provided in this invention enables the radar to be adapted for target detection in complex and variable environments. Figures 1 to 8 The method includes:

[0028] S101: Obtain guidance information on the current radar tracking status of the target in the search state. The guidance information includes avionics guidance information and radar target detection information. The radar target detection information includes at least the target range, signal-to-noise ratio, and health time. The avionics guidance information is the information sent to the radar by the aircraft's avionics system.

[0029] S102: In search mode, when the radar acquires the avionics guidance information, it calculates the critical detection range in search mode based on the guidance information, and preliminarily determines the number M of array elements that need to be turned off in search mode. Specifically...

[0030] The critical detection range R is determined by the actual distance of the target detected by the radar. c ;

[0031] Through the critical detection distance R c The ratio of radar's full-power detection range R to its critical detection range R c Based on the relationship between the ratio of array elements used and the actual number of array elements (M), the number of array elements (M) that need to be turned off is determined, satisfying the following:

[0032]

[0033] The required radiated power of the radar is determined by the number of array elements M that need to be turned off.

[0034] S103: In target tracking mode, the radar optimizes the number M of array elements that need to be turned off as determined in search mode. By determining the difference between the signal-to-noise ratio and the radar detection threshold, and using this difference as redundancy, the health time is evaluated. The critical detection range R in tracking mode is calculated by comprehensively optimizing the redundancy and the evaluation results.c To initially determine the number of array elements that need to be turned off in tracking mode, specifically:

[0035] When a target detects a radar signal exceeding its threshold, the probability of target acquisition needs to be reduced. The probability of target acquisition at time τ is defined as follows: Its expression is

[0036]

[0037] p fa To capture the false alarm probability of the receiver, P t For radar transmission power, G t For the radar transmitting antenna gain, G Ir To intercept the receiver's receiving antenna gain, where λ is the wavelength, G IP For the signal processing gain of the interceptor, R represents the range, k0 represents the Boltzmann constant, T0 represents the noise temperature of the radar receiver, and B... I To intercept the receiver's bandwidth, T I To capture the receiver's noise factor, π is the mathematical constant pi.

[0038] We can obtain the probability of the target being intercepted by the radar at time τ. With radar transmit power P t Related to the radial distance R, when only considering achieving low intercept effectiveness by changing the transmit power, the relationship between the radar's critical transmit power gain product and detection range is P. t G t ∝R 4 , where P t =P ti ×N, P ti G represents the peak power of a single array element, N is the total number of array elements, and G is the peak power of a single array element. t ∝N;

[0039] At the critical detection distance R c When, then P tc G tc ∝R c 4 , where P tc G tc To detect the gain product of transmit power after disabling some array elements, P tc =P ti ×(NM), where M is the number of closed array elements, G tc ∝(NM).

[0040] S104: Based on the number of array elements that need to be turned off in the tracking state, determine the pattern of the array elements to be turned off on the array surface. The pattern of the array elements to be turned off is determined according to the symmetrical equal circle method, and the calculation method is the same as the formula in S103.

[0041] Determine the total number of array elements N, and calculate the number of array elements M that need to be turned off. Specifically, the critical detection range R_c is determined based on the actual distance of the radar to detect the target aircraft.

[0042] By using the ratio of the critical detection range R_c to the radar's full-power detection range R, and its relationship with the ratio of array elements used, the number M of array elements that need to be turned off can be determined, thereby determining the radiation power required by the current radar.

[0043] The relationship between distance and number of array elements is expressed as:

[0044] The relationship between detection range and the proportion of closed array elements is as follows: Figure 2 As shown:

[0045] Once the detection range is determined, the number of array elements that need to be shut down can be determined accordingly. Taking a 32-element linear array as an example, the element spacing is... Pointing to 0°, as Figure 3 and Figure 4 As shown, the radiation pattern before and after disabling some array elements displays zero-depth losses of 1.15dB for the path gain and 0.904dB for the difference beam, which meet the design requirements. Taking a 608-element circular array as an example, the specific array arrangement is as follows: Figure 5 As shown, the spacing between adjacent array elements is λ / 2, and the beam direction is (0°, 0°), as... Figure 5 As shown in the simulation results, the difference beam null depth, beamwidth, and pattern gain change with the shutdown of array elements, correspondingly altering the angle measurement accuracy, grating lobe position, and sidelobe amplitude. Specifically, strategy 1 exhibits a pattern gain loss of 1.16 dB, and strategy 2 a pattern gain loss of 2.65 dB, meeting the design requirements. In practical applications, the specific array elements to be shut down must be determined comprehensively based on the angle measurement accuracy error and the detection range.

[0046] S105: Evaluate the pattern of the array elements to be shut down, convert the array element pattern into an antenna pattern, determine the grating lobe positions in the antenna pattern, and then determine the pattern of the shut-down array elements that has the least impact on radar performance. Specifically:

[0047] Based on the required number M of array elements to be shut down in search mode and the required number of array elements to be shut down in tracking mode, the shapes of the array elements to be shut down are determined on the array surface. The shapes of the array elements to be shut down are determined according to the symmetrical equal circle method, for example, Figure 6 The circles connected by the black line represent the number of array elements M that need to be turned off (when the radar is in target tracking mode). Figure 7 The circle used in the closed loop is represented by A, which indicates the number M of array elements that need to be turned off by the radar in the search state. The figure includes multiple array elements to be turned off.

[0048] The pattern of the array elements to be shut down is evaluated (the optimal pattern and number need to be determined in each state). The array element pattern is converted into an antenna pattern and the grating lobe positions in the pattern are determined. Evaluation is performed at least by considering the differential beam null depth, main-side lobe ratio, and radar scanning range. The evaluation method is as follows: a threshold is set, which is determined based on the radar performance. Based on the threshold, the array element pattern with the least impact on radar performance is obtained. The antenna pattern and grating lobe positions will also change after the array elements are shut down. The impact of the array element pattern in step 4 on target detection, angle measurement accuracy, and grating lobe positions is evaluated by considering the differential beam null depth, main-side lobe ratio, and radar scanning range. If the impact exceeds the threshold, the array element pattern can be changed accordingly. Through several iterations, the array element pattern with the least impact on performance can be obtained. The optimal radio frequency stealth scheme is selected from the array element shutdown strategy library to control the switching of radar array elements, achieving radiated power management. Figure 8 As shown, by selecting some different array element shutdown ratio schemes from the array element shutdown strategy library, the main lobe and side lobe amplitudes did not show significant performance differences, which met the design requirements.

[0049] S106: Optimization process to determine the final number of array elements to be shut down. Specifically,

[0050] The diagram for minimizing the impact on performance by shutting down array elements involves transmitting signals via the antenna after the array elements are shut down. The signal-to-noise ratio of the target echo signal and the health time of tracking are evaluated. If the radar's detection and tracking performance deteriorates due to a decrease in radiated power or RCS flicker (since the critical position is used as a reference, too many array elements may be shut down, resulting in insufficient radiated power of the radar), then redundancy management is required as needed. The number of array elements shut down should be appropriately reduced to ensure that the radiated power meets the usage requirements.

[0051] In engineering implementation, current T / R modules primarily focus on power output efficiency and other indicators in the saturation region. Controlling the output power in the linear region is difficult (due to low control precision), and imbalances in output power among different T / R modules in the linear region can cause a decline in indicators such as sidelobes. However, using a shrinking array method for radiated power control is relatively easy to implement in engineering. This invention uses the equal-circle method for element-level power switching control and optimizes the radiating element pattern by evaluating angular measurement accuracy and grating lobe positions, achieving optimal matching between radiated power control and detection performance, and minimizing radar detection performance loss. The key feature of this method is that, based on the target echo signal-to-noise ratio and health time, without changing the radar's equivalent aperture, it dynamically adjusts the radar's radiated power through precise switching of the radar radiating elements, thereby improving the radar's low-intercept performance.

[0052] The product provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the invention claims.

Claims

1. A method for adaptive power management of an active phased array radar, enabling the radar to detect targets in complex and variable environments, characterized in that, The method includes: The system acquires guidance information for the current radar target search and tracking states. The guidance information includes avionics guidance information and radar target detection information. The radar target detection information includes at least the target range, signal-to-noise ratio, and health time. The avionics guidance information is information sent to the radar by the aircraft's avionics system. In the search state, when the radar acquires the avionics guidance information, it calculates the critical detection range in the search state based on the guidance information and preliminarily determines the number M of array elements that need to be turned off in the search state. In target tracking mode, the radar optimizes the number M of array elements that need to be shut down as determined in search mode. It uses the difference between the signal-to-noise ratio and the radar detection threshold as a redundancy to evaluate the health time. Finally, it calculates the critical detection range in tracking mode by comprehensively optimizing the redundancy and the evaluation results. To initially determine the number of array elements that need to be turned off in tracking mode; Based on the number of array elements that need to be turned off under the tracking state, the pattern of the array elements to be turned off is determined on the array surface. The pattern of the array elements to be turned off is determined according to the symmetrical equal circle method. The pattern of the array element to be shut down is evaluated, the array element pattern is converted into an antenna pattern, the position of the grating lobe in the antenna pattern is determined, and then the pattern of the shut-down array element with the least impact on radar performance is determined. The optimization process determines the final number of array elements to be shut down.

2. The method according to claim 1, characterized in that, In target tracking mode, the radar optimizes the number M of array elements that need to be shut down as determined in search mode. It uses the difference between the signal-to-noise ratio and the radar detection threshold as a redundancy to evaluate the health time. Finally, it calculates the critical detection range in tracking mode by comprehensively optimizing the redundancy and the evaluation results. To initially determine the number of array elements that need to be turned off in tracking mode, including: When a target detects a radar signal exceeding its threshold, the probability of target acquisition needs to be reduced. The probability of target acquisition at time τ is defined as follows: Its expression is ,in, To intercept the false alarm probability of the receiver, For radar transmission power, For radar transmitting antenna gain, To intercept the receiver's receiving antenna gain, For wavelength, To intercept the receiver's signal processing gain, Represents distance, Represents the Boltzmann constant. The noise temperature represents the radar receiver. To intercept the receiver's bandwidth, To capture the receiver's noise factor, π is the mathematical constant pi. ； Therefore, the target is... Probability of radar interception at any given time With radar transmission power and radial distance Relatedly, when only considering achieving low intercept effectiveness by changing the transmit power, the relationship between the product of the radar's critical transmit power and gain and the detection range is as follows: ,in, , Where N is the peak power of a single array element, and N is the total number of array elements. ; At critical detection distance At that time, ,in, To detect the product of transmit power and gain after turning off some array elements, M is the number of closed array elements. .

3. The method according to claim 2, characterized in that, In search mode, when the radar acquires the avionics guidance information, it calculates the critical detection range in search mode based on the guidance information, and preliminarily determines the number M of array elements that need to be turned off in search mode, including: The critical detection range is determined by the actual distance of the target detected by the radar. ; Through critical detection distance The ratio of radar's full-power detection range R to its critical detection range Based on the relationship between the ratio of array elements used and the actual number of array elements (M), the number of array elements (M) that need to be turned off is determined, satisfying the following: ； The required radiated power of the radar is determined by the number of array elements M that need to be turned off.

4. The method according to claim 3, characterized in that, Based on the number of array elements that need to be shut down under tracking conditions, the pattern of the array elements to be shut down is determined on the array surface. The pattern of the array elements to be shut down is determined according to the symmetrical equal circle method, including: The graphs of the array elements to be turned off in the search state and the target tracking state are evaluated, and the array element graphs are converted into antenna radiation patterns and the positions of the grating lobes in the graphs are determined. The differential beam null depth, main-side lobe ratio, and radar scanning range are evaluated. A threshold is set based on the radar performance, and the graph of the shut-off array element with the least impact on radar performance is obtained based on the threshold.

5. The method according to claim 4, characterized in that, Optimization processing is performed to determine the final number of elements to be shut down, including: The image with the least impact on performance is the one where the array elements are turned off. After the array elements are turned off, the signal is transmitted through the antenna to evaluate the signal-to-noise ratio of the target echo signal and the health time of tracking. If the radar detection and tracking performance deteriorates due to a decrease in radiated power or RCS flicker, a preset number of array elements are given to compensate for the deterioration. Alternatively, the operator can manually increase or decrease the number of array elements based on the display on the radar interface.

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