Multi-carrier frequency MIMO radar adaptive waveform design method

Abstract

The invention belongs to the technical field of airborne fire control radars, and particularly relates to a multi-carrier-frequency MIMO radar adaptive waveform design method, which can realize optimal matching of a medium-heavy tracking waveform in a radar multi-carrier-frequency mode by adding a medium-heavy tracking waveform selection method in the multi-carrier-frequency mode, reduce the probability that a tracking center falls into a main clutter as much as possible, and improve the reliability of the radar multi-carrier-frequency mode. And the target tracking stability is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of airborne fire control radars, and in particular relates to a multi-carrier frequency MIMO radar adaptive waveform design method. Background Art

[0002] With the development of aviation equipment, the battlefield environment faced by airborne radars has become complex and changeable. The bottleneck of traditional radars in adapting to the modern electronic battlefield has become increasingly obvious, and the performance requirements for radars have become increasingly higher. This has urgently required a new radar system to bring new directions to this field.

[0003] With the emergence and development of MIMO radar, traditional electronic warfare jamming measures seem to be inadequate, which has opened up new avenues for radar anti-jamming technology and brought new challenges to electronic warfare.

[0004] The design of traditional MIMO (multiple input multiple output) radar transmission waveforms is all designed around orthogonal waveforms. If waveform orthogonality or coherence is to be achieved, the carrier frequencies between the transmitting array elements must be the same. Although such a design can improve the detection power, reduce the transmission power, and achieve a certain degree of LPI (low probability of intercept) effect, when facing contemporary new jammers, the opponent has high receiving sensitivity and strong processing capabilities, and the single carrier frequency can be easily intercepted and interfered by the opponent. In particular, when the opponent is a stealth platform, when implementing self-defense interference, the power spectrum density is conventionally reduced, and the opponent can still easily intercept the detection radar signal from the energy dimension. To this end, the radar needs to expand to a multi-carrier form in the frequency dimension, increase the difficulty of the opponent's electronic warfare sorting, identification and interference, and enhance the anti-interference capability of its own radar.

[0005] In recent years, researchers have been trying to combine MIMO radar with frequency diversity and conducting research on MIMO radar systems from the perspective of frequency diversity. Since frequency diversity is reflected in the array working on different carrier frequencies, frequency diversity MIMO radar is also called multi-carrier MIMO radar.

[0006] Since the actual application of multi-carrier frequency radar is still relatively small, compared with the traditional single-carrier frequency radar, compared with the huge improvement in anti-interference ability, the multi-carrier frequency radar needs the antenna to radiate multiple signals at the same time, resulting in a loss of some detection power. In the same scenario, for the same target, due to the decrease in detection power, the detection probability of the multi-carrier frequency radar will also be reduced compared with the traditional single-carrier frequency radar, especially when the target is maneuvering, such as passing through a speed notch. Therefore, relevant measures need to be taken to improve the detection probability of the multi-carrier frequency radar in this scenario. Summary of the invention

[0007] In view of this, the present invention provides a multi-carrier MIMO radar adaptive waveform design method. By adding a medium-weight tracking waveform selection method in the multi-carrier mode, the optimal matching of the medium-weight tracking waveform in the radar multi-carrier mode can be achieved, the probability of the tracking center falling into the main clutter can be reduced as much as possible, and the target tracking stability can be improved.

[0008] The technical solution of the present invention is:

[0009] A multi-carrier frequency MIMO radar adaptive waveform design method comprises the following steps:

[0010] Step 1: When the radar is in the target tracking state and enters the waveform selection, determine whether the radar has turned on the multi-carrier mode;

[0011] Step 2: In non-multi-carrier mode, the radar selects the optimal mid-weight tracking waveform based on the main clutter, sidelobe clutter, image lobe clutter, front and rear occlusions, altitude lines, and target range and speed information;

[0012] In the multi-carrier frequency mode, the radar selects a specific frequency group as the radar carrier frequency according to the anti-interference requirements, and calculates the main clutter areas corresponding to different carrier frequencies of the specific frequency group respectively;

[0013] Step 3: Determine whether the target tracking center does not fall within the main clutter area corresponding to all carrier frequencies of the specific frequency group. If so, update the value range of the maximum main clutter area and restart the selection of medium-heavy waveforms until all do not fall within the area.

[0014] Further, in step 3, if

[0015] If all waveforms are still not included after traversing, the frequency combination of the selected specific frequency group is adjusted and step 3 is executed again.

[0016] Further, in step 1:

[0017] When the radar works in multi-carrier frequency mode, each RF module of the radar is independently configured with one radar carrier frequency as quadrant excitation; when the radar receives signals, the antenna performs full array reception, and each RF module only receives the radar carrier frequency of its own module;

[0018] Further, in said step 2;

[0019] The method for selecting the optimal mid-weight tracking waveform includes:

[0020] S201 selects the optimal area of ​​the medium-heavy tracking waveform, which can avoid main clutter, sidelobe clutter, image lobe clutter, front and rear occlusions, and altitude line clutter to the greatest extent;

[0021] S202 selects the optimal waveform according to the optimal region.

[0022] Further, in S201, when selecting the regional division of each waveform under a specific frequency group, the position of the leading and trailing edges of the main clutter caused by the situation of main clutter ambiguity is referred to.

[0023] Further, in S201, the regional selection order strategy is as follows: count which region of the waveform the tracking center falls into, determine the selection region order according to the radio altitude. If the tracking center falls in the main clutter region, the region between the front occlusion and the altitude line is selected to the greatest extent; if the waveforms of the tracking center do not fall into the main clutter region, then select the non-occluded region waveform and avoid the clutter of the altitude line.

[0024] Further, in step 2, when the main clutter is not ambiguous, that is, when the leading edge of the main clutter region > 0 and the trailing edge of the main clutter < PRF:

[0025] Calculate the main clutter frequency corresponding to each carrier frequency:

[0026]

[0027] where v is the flight speed of the carrier aircraft, λ i is the wavelength corresponding to different carrier frequencies, θ is the azimuth angle, is the pitch angle, considering the influence of the earth's curvature radius, there is:

[0028]

[0029] where H is the altitude of the carrier aircraft, R c is the slant range;

[0030] After that, calculate the left and right protection areas of the main clutter according to the main clutter protection speed respectively:

[0031]

[0032]

[0033] In the multi-carrier frequency mode, the main clutter region corresponding to each carrier frequency is:

[0034]

[0035] Further, step 3 is specifically as follows:

[0036] Match the main clutter region calculated for each carrier frequency with the tracking center. Confirm that the tracking center does not fall into the main clutter region corresponding to any carrier frequency. When the tracking center falls into the main clutter region, update the value range of the main clutter region selected for the medium and heavy tracking waveform selection. The updated main clutter region is selected as:

[0037]

[0038] Afterwards, the new main clutter area is used as input to reselect the mid-re-tracking waveform so that the tracking center does not fall within the main clutter area of ​​any carrier frequency.

[0039] The beneficial effects of the present invention are:

[0040] Compared with the existing medium-weight tracking waveform selection method, the present invention can achieve the optimal matching of the medium-weight tracking waveform in the radar multi-carrier mode by adding the medium-weight tracking waveform selection method in the multi-carrier mode, reduce the probability of the tracking center falling into the main clutter as much as possible, and improve the target tracking stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 is a decision flow chart in a specific implementation manner of the present invention;

[0043] Figure 2 This is a diagram of the transceiver mode of a multi-carrier radar;

[0044] Figure 3 It is the main clutter protection zone and tracking center of the lower frequency 1 in the multi-carrier mode;

[0045] Figure 4 It is the main clutter protection zone and tracking center of the second carrier in multi-carrier mode. DETAILED DESCRIPTION

[0046] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0047] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0048] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0049] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure. The illustrations only show components related to the present disclosure rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0050] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0051] In one embodiment of the present invention, a multi-carrier MIMO radar adaptive waveform design method is proposed, comprising the following steps:

[0052] Step 1: When the radar is in the target tracking state and enters the waveform selection, determine whether the radar has turned on the multi-carrier mode;

[0053] Step 2: In non-multi-carrier mode, the radar selects the optimal mid-weight tracking waveform based on the main clutter, sidelobe clutter, image lobe clutter, front and rear occlusions, altitude lines, and target range and speed information;

[0054] In the multi-carrier frequency mode, the radar selects a specific frequency group as the radar carrier frequency according to the anti-interference requirements, and calculates the main clutter areas corresponding to different carrier frequencies of the specific frequency group respectively;

[0055] Step 3: Determine whether the target tracking center does not fall within the main clutter area corresponding to all carrier frequencies of the specific frequency group. If so, update the value range of the maximum main clutter area and restart the selection of medium-heavy waveforms until all do not fall within the area.

[0056] In this embodiment, in step 3, if

[0057] If all waveforms are still not included after traversing, the frequency combination of the selected specific frequency group is adjusted and step 3 is executed again.

[0058] In this embodiment, in step 1:

[0059] When the radar works in multi-carrier frequency mode, each RF module of the radar is independently configured with one radar carrier frequency as quadrant excitation; when the radar receives signals, the antenna performs full array reception, and each RF module only receives the radar carrier frequency of its own module;

[0060] In this embodiment, in step 2;

[0061] The method for selecting the optimal mid-weight tracking waveform includes:

[0062] S201 selects the optimal area of ​​the medium-heavy tracking waveform, which can avoid main clutter, sidelobe clutter, image lobe clutter, front and rear occlusions, and altitude line clutter to the greatest extent;

[0063] S202 selects an optimal waveform according to the optimal area.

[0064] In this embodiment, in S201, when selecting the area division of each waveform under a specific frequency group, the position of the leading and trailing edges of the main clutter caused by the ambiguity of the main clutter is referred to;

[0065] In this embodiment, in S201, the area selection order strategy is: count which area of ​​the waveform the tracking center falls into, determine the area selection order according to the radio altitude, if the tracking centers all fall into the main clutter area, select the area between the front block and the height line to the greatest extent; if the waveform of the tracking center does not fall into the main clutter area, select the waveform of the non-block area and avoid the height line clutter;

[0066] In this embodiment, in step 2, when the main clutter is not ambiguous, that is, the leading edge of the main clutter area is greater than 0, and the trailing edge of the main clutter is less than PRF:

[0067] Calculate the main clutter frequency corresponding to each carrier frequency:

[0068]

[0069] Where v is the flight speed of the aircraft, λ i is the wavelength corresponding to different carrier frequencies, θ is the azimuth angle, is the pitch angle, and the influence of the earth's curvature radius is:

[0070]

[0071] Where H is the height of the aircraft, R c is the slope distance;

[0072] Then, the left and right protection areas of the main clutter are calculated according to the main clutter protection speed:

[0073]

[0074]

[0075] In multi-carrier frequency mode, the main clutter area corresponding to each carrier frequency is:

[0076]

[0077] In this embodiment, step 3 is specifically as follows:

[0078] Match the main clutter area calculated for each carrier frequency with the tracking center to confirm that the tracking center does not fall within the main clutter area corresponding to any carrier frequency. If the tracking center falls within the main clutter area, update the value range of the main clutter area selected by the re-tracking waveform. The updated main clutter area is selected as:

[0079]

[0080] Afterwards, the new main clutter area is used as input to reselect the mid-re-tracking waveform so that the tracking center does not fall within the main clutter area of ​​any carrier frequency.

[0081] The traditional medium-weight tracking waveform selection process designed for a single carrier frequency is not completely applicable to radars that support multiple carrier frequencies, because different carrier frequencies will cause different main clutter areas, resulting in the tracking center not being able to completely avoid the non-detection area. This embodiment dynamically adjusts the main clutter area according to different carrier frequencies based on the traditional process to achieve optimal selection of medium-weight tracking waveforms, thereby improving target detection probability and target tracking stability.

[0082] This embodiment proposes a multi-carrier MIMO radar adaptive waveform design method. According to different carrier frequencies, without affecting the selection of medium-heavy tracking waveforms, the medium-heavy tracking waveform is selected by dynamically adjusting the main clutter interval so that the tracking center always falls in the clear area, thereby improving the radar tracking stability. The method flow chart is as follows: Figure 1 As shown, the present invention is further described below through specific implementation methods.

[0083] Step 1: When the radar is in the target tracking state and enters the waveform selection state, determine whether the radar is in the multi-carrier working mode;

[0084] When the radar works in multi-carrier mode, each RF module is independently configured with a radar carrier frequency for use as quadrant excitation; when receiving, the antenna performs full array reception, but each RF module only receives the radar carrier frequency of its own module, such as Figure 2 shown.

[0085] Step 2: In non-multi-carrier mode, the radar selects the optimal mid-weight tracking waveform based on the main clutter, sidelobe clutter, image lobe clutter, front and rear occlusions, altitude line, target distance and speed, etc.

[0086] The optimal waveform for medium-weight tracking must meet the following requirements: try to avoid main clutter, sidelobe clutter, image lobe clutter, front and rear occlusions, and altitude line clutter, select the optimal area, and select the optimal waveform in the optimal area.

[0087] 1) When dividing the area, the ambiguity of the main clutter needs to be considered, that is, the position of the leading and trailing edges of the main clutter needs to be considered;

[0088] 2) Area selection order strategy: Count the area of ​​the waveform in which the tracking center falls, and determine the order of area selection according to the radio altitude. If they all fall in the main clutter area, try to select the area between the front block and the altitude line. If there is a waveform that is not in the main clutter area, select the waveform in the non-block area and avoid the altitude line clutter.

[0089] 3) According to the area division strategy, all waveforms are traversed to determine whether they fall into the main clutter area, and the optimal waveform is selected based on the front and rear occlusions, altitude lines, target distance and speed and other information.

[0090] Step 3: In the multi-carrier frequency mode, the radar selects a specific frequency group as the radar carrier frequency according to the anti-interference requirements, and calculates the main clutter area corresponding to different carrier frequencies respectively;

[0091] For a target detected in a single quadrant, when tracking is initiated and scheduled for confirmation, the tracking center calculated based on the current quadrant and its frequency point is used. However, the frequency point of each quadrant is different. When the tracking center calculated based on a single quadrant is converted to the quadrant corresponding to other carrier frequencies, the phase center will inevitably shift, and there is a high probability that it will fall into the main clutter protection zone, resulting in the inability to correlate the corresponding quadrant after detecting the target, affecting the target tracking stability.

[0092] Considering the case where the main clutter is not ambiguous, that is, the leading edge of the main clutter area is greater than 0, and the trailing edge of the main clutter is less than PRF:

[0093] First, calculate the main clutter frequency corresponding to each carrier frequency:

[0094]

[0095] Where v is the flight speed of the aircraft, λ i is the wavelength corresponding to different carrier frequencies, θ is the azimuth angle, is the pitch angle. Considering the influence of the earth's curvature radius, equation (1) can be expressed as:

[0096]

[0097] Where H is the height of the aircraft, R c is the slant distance. According to the main clutter protection speed, the left and right protection zones of the main clutter are calculated respectively:

[0098]

[0099]

[0100] Therefore, in the multi-carrier mode, the main clutter area corresponding to each carrier frequency is:

[0101]

[0102] Step 4: Determine whether the tracking center does not fall within the main clutter area corresponding to all carrier frequencies. If not, return to select the largest main clutter area as input and restart the medium-heavy waveform selection;

[0103] Match the main clutter area calculated for each carrier frequency with the tracking center to confirm that the tracking center does not fall within the main clutter area corresponding to any carrier frequency. If the tracking center falls within the main clutter area, it is necessary to update the value range of the main clutter area selected by the mid-re-tracking waveform. The new main clutter area is selected as:

[0104]

[0105] The new main clutter area is used as input to reselect the mid-re-tracking waveform so that the tracking center does not fall within the main clutter area of ​​any carrier frequency.

[0106] Step 5: If the requirements are still not met after traversing all waveforms, adjust the frequency combination and restart the process.

[0107] Example: Figure 3 and Figure 4 The receiving spectra of the two quadrants of the radar in the multi-carrier frequency mode are shown respectively. The three vertical lines on the spectrum represent the left edge (leading edge) of the main clutter, the center of the main clutter and the right edge (trailing edge) of the main clutter from left to right. It is obvious that the main clutter areas of the two quadrants under different carrier frequencies are inconsistent. Figure 3 The clear area of ​​the spectrum outside the main clutter is Figure 4 The clear area of ​​the spectrum is also inconsistent. At this time, the tracking center cannot be selected in Figure 3 The trailing edge of the main clutter Figure 4 Between the leading edge of the main clutter and Figure 3 The main clutter front and Figure 4 Between the trailing edges of the main clutter, finally, the tracking center on the spectrum is optimized through the medium and heavy tracking waveform so that it falls within the clear area of ​​the two spectra, which improves the probability of scheduling detection and thus improves the radar tracking stability.

[0108] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A multi-carrier MIMO radar adaptive waveform design method, characterized in that , including the following steps: Step 1: When the radar is in the target tracking state and enters the waveform selection, determine whether the radar has enabled the multi-carrier frequency mode; Step 2: In the non-multi-carrier frequency mode, the radar selects the optimal medium-weight tracking waveform based on the main clutter, sidelobe clutter, mirror lobe clutter, front and rear occlusion, altitude line, and target range-velocity information; In the multi-carrier frequency mode, the radar selects a specific frequency group as the radar carrier frequency according to the anti-jamming requirements, and calculates the main clutter regions corresponding to different carrier frequencies of the specific frequency group respectively; Step 3: Determine whether the target tracking center does not fall within the main clutter regions corresponding to all the carrier frequencies of the specific frequency group. If it falls, update the value range of the maximum main clutter region, and restart the medium-weight waveform selection until it does not fall completely.

2. The multi-carrier frequency MIMO radar adaptive waveform design method according to claim 1, characterized in that , in Step 3, if After traversing all waveforms and still not meeting the condition of not falling completely, adjust the frequency combination of the selected specific frequency group, and then re-execute Step 3.

3. The multi-carrier frequency MIMO radar adaptive waveform design method according to claim 2, characterized in that , in Step 1: When the radar operates in the multi-carrier frequency mode, each RF module of the radar is independently configured with 1 radar carrier frequency for quadrant excitation; when the radar receives signals, the antenna performs full-array reception, and each RF module only receives the radar carrier frequency of its own module.

4. The multi-carrier frequency MIMO radar adaptive waveform design method according to claim 3 is characterized in that , in Step 2; The selection method of the optimal medium-weight tracking waveform includes: S201 Select the optimal region of the medium-weight tracking waveform. The optimal region can avoid the main clutter, sidelobe clutter, mirror lobe clutter, front and rear occlusion, and altitude line clutter to the greatest extent; S202 Select the optimal waveform according to the optimal region.

5. The multi-carrier frequency MIMO radar adaptive waveform design method according to claim 4, characterized in that , in S201, when selecting the region division of each waveform under a specific frequency group, refer to the position of the front and rear edges of the main clutter caused by the ambiguity of the main clutter.

6. The multi-carrier frequency MIMO radar adaptive waveform design method according to claim 5, characterized in that , in S201, the region selection order strategy is: count which region of the waveform the tracking center falls into, determine the selection region order according to the radio altitude. If the tracking center falls within the main clutter region, select the region between the front occlusion and the altitude line to the greatest extent; if the waveforms of the tracking center do not fall within the main clutter region, select the non-occluded region waveform and avoid the altitude line clutter.

7. The multi-carrier frequency MIMO radar adaptive waveform design method according to claim 6, characterized in that , in Step 2, when the main clutter is not ambiguous, that is, when the front edge of the main clutter region > 0 and the rear edge of the main clutter < PRF: Calculate the main clutter frequency corresponding to each carrier frequency: Where v is the flight speed of the aircraft, λ i is the wavelength corresponding to different carrier frequencies, θ is the azimuth angle, is the pitch angle, and the influence of the earth's curvature radius is: Where H is the height of the aircraft, R c is the slope distance; Then calculate the left and right protection regions of the main clutter according to the main clutter protection speed respectively: In the multi-carrier frequency mode, the main clutter region corresponding to each carrier frequency is:

8. The multi-carrier frequency MIMO radar adaptive waveform design method according to claim 7, characterized in that , Step 3 is specifically: Match the main clutter region calculated for each carrier frequency with the tracking center, confirm that the tracking center does not fall within the main clutter region corresponding to any carrier frequency. When the tracking center falls within the main clutter region, update the value range of the main clutter region for the medium-weight tracking waveform selection. The updated main clutter region is selected as: Then use the new main clutter region as the input to re-perform the medium-weight tracking waveform selection, so that the tracking center does not fall within the main clutter region of any carrier frequency.

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