Phased array radar ambiguity resolution method based on double repetition frequencies

Abstract

The invention discloses a phased array radar ambiguity resolution method based on double repetition frequencies, and the method comprises the steps: selecting a double repetition carrier frequency transmitting signal which needs to meet an unambiguous distance detection requirement, an unambiguous speed detection requirement and a blind area constraint requirement at the same time; determining a pulse emission time sequence; performing speed ambiguity resolution processing to obtain the real speed of the target; performing distance ambiguity resolution processing to obtain a real distance Rr of the target; and outputting the target real speed and the target real distance Rr. The method has the advantages that the speed ambiguity resolution process and the distance ambiguity resolution process are separated by introducing the double-carrier-frequency design to each repetition frequency, on one hand, the pairing problem and the ghosting problem existing in two-dimensional ambiguity resolution of a coincidence algorithm are relieved, on the other hand, the space filling time of the phased array radar is greatly shortened, and the robustness of target ambiguity resolution is improved.

Description

Technical Field

[0001] This invention relates to the field of radar technology, and in particular to a deambiguation method for phased array radar based on dual repetition frequencies, namely a dual repetition frequency deambiguation method for phased array radar, which can be applied to the deambiguation of range and velocity in phased array early warning radar. Background Technology

[0002] Medium repetition rate (MRPR) radar systems suffer from range and velocity ambiguity. Conventional ground-based and airborne early warning radars typically employ coincidence algorithms to achieve two-dimensional deambiguity resolution. However, applying this algorithm to phased array radars faces several technical challenges:

[0003] 1) Distance defuzzification constraint: The algorithm requires that the target distance and position must be unique. If there are multiple targets in the same distance cell, the correct pairing cannot be achieved.

[0004] 2) False alarm problem in multi-target environment: The fuzzy distance / velocity corresponding to multiple repetition frequencies may overlap; as the number of repetition frequencies and the number of targets increases, the ghost phenomenon shows an exponential growth; ghost interference seriously affects the accuracy of target recognition.

[0005] Based on the above, it is clear that existing defuzzification methods need to be improved.

[0006] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art. Summary of the Invention

[0007] Based on the aforementioned technical problems, the purpose of this invention is to provide a phased array radar deambiguation method based on dual repetition frequencies. This method introduces a dual carrier frequency design for each repetition frequency, separating the velocity deambiguation and range deambiguation processes. On the one hand, it alleviates the pairing problem and ghosting problem existing in the two-dimensional deambiguation of the coincidence algorithm. On the other hand, it significantly reduces the spatial filling time of the phased array radar and improves the robustness of target deambiguation.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0009] A deambiguity resolution method for phased array radar based on dual repetition frequencies, comprising:

[0010] A dual-repetition carrier frequency transmission signal is selected, which must simultaneously meet the requirements of unambiguous range detection, unambiguous velocity detection, and blind zone constraint. The two pulse repetition frequencies used for unambiguity resolution at a certain wavelength are set as the first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2. For each pulse repetition frequency, the phased array radar system uses two carrier frequency transmission signals, and the wavelengths corresponding to the two carrier frequency transmission signals are the first transmission wavelength λ1 and the second transmission wavelength λ2, respectively.

[0011] The pulse transmission timing is determined, which includes four coherent processing time periods. The order of the transmission signal parameters in each time period is (PRF1, λ1), (PRF1, λ2), (PRF2, λ1) and (PRF2, λ2).

[0012] For the echo signals of the coherent processing time corresponding to the first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2, velocity deblurring processing is performed to obtain the true velocity of the target.

[0013] Perform distance deblurring to obtain the true target distance R. r ;

[0014] Output the target's true velocity and true distance R. r .

[0015] Optionally, the unambiguous distance detection requirement and the unambiguous velocity detection requirement are expressed as follows:

[0016]

[0017] Wherein, the symbol (·) represents the least common multiple operation, c represents the speed of light, Ru is the unambiguous detection range required by the phased array radar system, and Vu is the unambiguous detection speed required by the phased array radar system.

[0018] The blind zone constraint requirements include:

[0019] (1) The target velocity must not be blurred into the main lobe clutter region. The first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2 must satisfy the following constraints:

[0020]

[0021] Based on the above formula, the minimum value of the pulse repetition frequency can be obtained, where V represents the satellite's orbital velocity, θ is the 3dB beamwidth of the radar azimuth antenna, and v r_max The target's maximum radial velocity relative to the radar;

[0022] (2) Ensure that the main lobe of the signal is not blurred in distance. If distance blur cannot be completely avoided, select a smaller first pulse repetition frequency PRF1 and second pulse repetition frequency PRF2 to reduce the number of distance blurs in the main lobe of the transmitted pulse signal. The coherent processing interval of each coherent processing period must be kept consistent.

[0023] Optionally, during velocity deambiguation, the phased array radar system employs a dual-carrier frequency alternating transmission mode according to a pre-set pulse transmission sequence, utilizing the velocity deambiguation of two different carrier frequency transmission signals with the same pulse repetition frequency. The velocity deambiguation includes:

[0024] In the first transmission wavelength λ1 signal processing stage, the pulse echo signal of the first transmission wavelength λ1 is used to detect the target, obtain the apparent velocity v0 of the target, and calculate the possible velocity v of the target based on the apparent velocity v0.

[0025] In the second transmission wavelength λ2 signal processing stage, the pulse echo signal of the second transmission wavelength λ2 is used to detect the target, obtain the apparent velocity v0 of the target, and calculate the possible velocity v of the target based on the apparent velocity v0.

[0026] Multi-wavelength data velocity cross-validation processing involves cross-validating the possible velocity v sets obtained from two different transmission wavelengths, combining the possible velocities v obtained from different transmission wavelengths, applying an overlap algorithm to de-ambiguate, and determining the true velocity of the target.

[0027] Optionally, taking the first pulse repetition frequency PRF1 as an example, the method for calculating the possible velocity v of the target includes:

[0028] When the phased array radar system transmits the carrier frequency transmission signal with the first transmission wavelength λ1

[0029] If the apparent velocity of the target is v0 > 0, then the possible velocities v are:

[0030] ν = v0 or i = 1 or 2;

[0031] If the apparent velocity of the target is v0 < 0, then the possible velocities v are:

[0032] ν = v0 or i = 1 or 2;

[0033] When the phased array radar system transmits a carrier frequency transmission signal with a second transmission wavelength λ2

[0034] If the apparent velocity of the target is v0 > 0, the possible velocities v are:

[0035] ν = v0 or i = 1 or 2;

[0036] If the apparent velocity of the target is v0 < 0, the possible velocities v are:

[0037] ν = v0 or i = 1 or 2.

[0038] Optionally, when only one transmission wavelength detects the target at a single pulse repetition frequency, the apparent velocity v0 of the target can be obtained by adjusting the detection threshold of the other transmission wavelength.

[0039] Optionally, the two carrier frequency transmission signals corresponding to the same pulse repetition frequency must satisfy the following:

[0040]

[0041] Among them, the center frequencies of the two carrier frequency transmission signals are the first center frequency f1 and the second center frequency f2 respectively, B represents the spectrum width of the transmission signal, and ν r_min is the minimum target speed recognizable by the phased array radar system, and CPI is the coherent processing interval of each coherent processing period.

[0042] Optionally, performing range ambiguity resolution processing includes:

[0043] Based on the leading edge times t1 and t2 of the pulse echo signals in the coherent processing periods of the first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2 under the same transmission wavelength, calculating the ambiguity order M, and then solving the true target range R r .

[0044] Optionally, the calculation method of the ambiguity order M includes:

[0045] When t1 < t2:

[0046]

[0047] When t1 > t2:

[0048]

[0049] When t1 = t2, M = 0.

[0050] Optionally, the true target range R r is calculated by the formula:

[0051] R r = c / 2 × (t1 + M × PRT1) or R r = c / 2 × (t2 + M × PRT2)

[0052] Among them, c is the speed of light.

[0053] Optionally, before performing velocity ambiguity resolution processing, it further includes:

[0054] Pulse compression, Doppler filtering processing, and phase adjustment.

[0055] The present invention has the following advantages compared with the prior art:

[0056] Compared to traditional coincidence algorithms, the phased array radar deblurring method based on dual repetition frequencies proposed in this invention separates the velocity deblurring and range deblurring processes by introducing a dual carrier frequency design for each repetition frequency. On the one hand, this alleviates the pairing problem and ghosting problem existing in the two-dimensional deblurring of the coincidence algorithm, and on the other hand, it significantly reduces the spatial filling time of the phased array radar and improves the robustness of target deblurring. Attached Figure Description

[0057] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the drawings in the following description are one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0058] Figure 1 This is a schematic diagram of a phased array radar deambiguation method based on dual repetition frequencies according to the present invention;

[0059] Figure 2 The diagram shown is a schematic illustration of a target defuzzification process according to the present invention. Detailed Implementation

[0060] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed explanation of the phased array radar deambiguation method based on dual repetition frequencies proposed in this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions, used only to facilitate and clearly illustrate the embodiments of this invention. Please refer to the accompanying drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0061] This invention innovatively proposes a dual-repetition-frequency (PRF) deambiguation method for phased array radar, specifically a dual-carrier frequency deambiguation optimization method, to address the unique application requirements of phased array radar. The core technical solution of this method lies in: employing dual-carrier frequency modulation technology to decouple the range deambiguation and velocity deambiguation processes; and designing a dual-repetition-frequency signal that satisfies three basic constraints: unambiguous detection range constraint, unambiguous detection velocity constraint, and blind zone avoidance constraint. The signal transmission timing adopts a four-phase coherent processing design, with specific parameter configurations of (PRF1, λ1), (PRF1, λ2), (PRF2, λ1), and (PRF2, λ2).

[0062] The following example, using a phased array radar system to observe multiple targets, will be used to elaborate on the patent solution.

[0063] like Figure 1 and Figure 2 As shown, the phased array radar deambiguation method based on dual repetition frequency of the present invention includes:

[0064] S1. Select the double repetition frequency transmission signal (double repetition signal), that is, select the pulse repetition frequency.

[0065] When a phased array radar system performs beam scanning, the two pulse repetition frequencies used for deambiguation of a certain wave position are the first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2, respectively. The corresponding pulse repetition interval can be expressed as: For each pulse repetition frequency, the phased array radar system uses two carrier frequency transmission signals. The center frequencies corresponding to the two carrier frequency transmission signals are denoted as the first center frequency f1 and the second center frequency f2, respectively. The wavelengths corresponding to the two carrier frequency transmission signals are the first transmission wavelength λ1 and the second transmission wavelength λ2, respectively.

[0066] It should be noted that the dual-repetition carrier frequency transmission signal must simultaneously meet three conditions: unambiguous range detection requirement (unambiguous range detection condition), unambiguous velocity detection requirement (unambiguous velocity detection condition), and blind zone constraint requirement (blind zone restriction condition). The carrier frequency transmission signal can also be referred to as a frequency transmission signal or a wavelength pulse signal.

[0067] Specifically, the unambiguous distance detection requirement and the unambiguous velocity detection requirement can be expressed as follows:

[0068]

[0069] Wherein, the symbol (·) represents the least common multiple operation, c represents the speed of light, Ru is the unambiguous detection range required by the phased array radar system, and Vu is the unambiguous detection speed required by the phased array radar system.

[0070] The blind zone constraint requirement, or blind zone limitation condition analysis, states that when a phased array radar system operates in a mid-repetition-rate (MRFR) mode, both range blind zone and velocity blind zone typically exist simultaneously. The range blind zone is mainly caused by the masking effect, while the velocity blind zone is caused by main lobe clutter suppression and its periodic repetition in the Doppler domain. To address the blind zone problem, the MRFR design needs to adhere to the following principles:

[0071] (1) The target velocity must not be blurred into the main lobe clutter region. The first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2 must satisfy the following constraints:

[0072]

[0073] Based on the above formula, the minimum value of the pulse repetition frequency can be obtained, where V represents the satellite's orbital velocity, θ is the 3dB beamwidth of the radar azimuth antenna, and v r_max The target's maximum radial velocity relative to the radar;

[0074] (2) Ensure the main lobe of the signal is not blurred in terms of distance. If distance blurring cannot be completely avoided, select a smaller first pulse repetition frequency (PRF1) and second pulse repetition frequency (PRF2). That is, the first pulse repetition frequency (PRF1) and the second pulse repetition frequency (PRF2) should be as small as possible to reduce / minimize the number of distance blurring events in the main lobe signal of the transmitted pulse signal. This condition effectively limits the maximum value of the pulse repetition frequency. The coherent processing interval (CPI) for each coherent processing period must remain consistent.

[0075] On the other hand, in this invention, the two carrier frequency transmission signals, i.e., wavelength pulse signals, corresponding to the same pulse repetition frequency must satisfy the following:

[0076]

[0077] Wherein, the center frequencies of the two carrier frequency transmitted signals are the first center frequency f1 and the second center frequency f2, respectively, B represents the spectral width of the transmitted signal, i.e., the bandwidth, and ν r_min CPI represents the minimum target velocity that a phased array radar system can identify / detect, and CPI represents the coherent processing interval for each coherent processing period.

[0078] S2. Determine the pulse transmission timing. In this embodiment, the pulse transmission timing of the phased array radar system is divided into 4 coherent processing periods. The order of the transmitted signal parameters in each period is (PRF1, λ1), (PRF1, λ2), (PRF2, λ1), and (PRF2, λ2), and the coherent processing interval (CPI) of all periods remains consistent.

[0079] S3, pulse compression, Doppler filtering, and phase adjustment.

[0080] In practical applications, pulse compression primarily addresses the conflict between range resolution and detection range. The core idea of ​​pulse compression is to modulate the transmitted pulse (such as linear frequency modulation, phase coding, etc.) and then compress the wide pulse into a narrow pulse at the receiver through matched filtering or correlation processing, thereby simultaneously achieving high resolution and high signal-to-noise ratio.

[0081] Furthermore, the echo frequency of a stationary target is the same as the transmitted signal, while a moving target will generate a Doppler frequency shift. By processing the Doppler frequency shift through Doppler filtering, the radial velocity of the target can be directly calculated.

[0082] It should be noted that this invention does not limit the specific methods of pulse compression, Doppler filtering, and phase adjustment; any method that achieves the intended purpose is acceptable. For example, in one embodiment, phase adjustment is performed using digital phase rotation, where the complex signal is rotated or adjusted in digital signal processing (DSP). In another embodiment, phase adjustment is performed using a phase-locked loop (PLL), where the phase relationship between the transmitted and received signals is locked at the RF front end. In yet another embodiment, adaptive filtering is used, dynamically adjusting the phase weights based on algorithms such as minimum mean square error (LMS). It is understood that parts not described in detail in this specification are common knowledge to those skilled in the art and will not be elaborated upon here.

[0083] Based on the aforementioned phased array radar system, this invention proposes the following dual-repetition-frequency deambiguation method, which includes velocity deambiguation and range deambiguation. The velocity deambiguation and range deambiguation processes are separated. First, velocity ambiguity is deambigued using two different carrier frequencies with the same repetition frequency. Then, range ambiguity is deambigued using dual-repetition-frequency deambiguation in the one-dimensional range dimension. Specifically, the dual-repetition-frequency phased array radar deambiguation method of this invention further includes:

[0084] S4. For the echo signals of the coherent processing time corresponding to the first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2, perform one-dimensional velocity defuzzification processing to obtain the true velocity of the target.

[0085] In this invention, a multi-wavelength joint solution method is used to extract the true velocity of the target. During velocity deambiguation processing, the phased array radar system adopts a dual-carrier frequency alternating transmission mode according to a pre-set pulse transmission sequence. When the selected carrier frequency parameters meet the following requirements, the receiver can distinguish and process the signals of each phase coherence processing period by configuring different center frequency filters, thereby avoiding the signal filling time that must be set in traditional methods.

[0086]

[0087] Where B represents the spectral width, or bandwidth, of the transmitted signal, ν r_minCPI represents the minimum target velocity that a phased array radar system can identify / detect, and CPI represents the coherent processing interval for each coherent processing period.

[0088] Based on the above technical features, the velocity deblurring method proposed in this scheme can omit the filling time step. During velocity deblurring, it utilizes two different carrier frequency transmitted signals with the same pulse repetition frequency for velocity deblurring. Specifically, for the coherently processed echo signals generated by the first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2 used by the system, velocity deblurring is performed according to the following steps to finally obtain the actual velocity of the target:

[0089] S41. In the first transmission wavelength λ1 signal processing stage, target detection is performed on the pulse echo signal of the first transmission wavelength λ1 to obtain the target apparent velocity v0, and the target possible velocity v set is calculated based on the target apparent velocity v0; where the target apparent velocity v0 is also called the target apparent velocity or the target visible velocity.

[0090] S42, Second transmission wavelength λ2 signal processing stage, target detection is performed on the pulse echo signal of the second transmission wavelength λ2 to obtain the target apparent velocity v0, and the target possible velocity v set is calculated based on the target apparent velocity v0;

[0091] S43. Multi-wavelength data velocity cross-validation processing: Cross-validation is performed on the possible velocity sets v obtained from two different transmission wavelengths. The possible velocities v obtained from different transmission wavelengths are combined, and an optimal matching algorithm is applied to eliminate velocity ambiguity. For example, an overlap algorithm is used to de-ambiguate and determine the target's true velocity. In other words, joint velocity ambiguity resolution combines the possible velocity v estimates from two different transmission wavelengths, and then applies an overlap algorithm to de-ambiguate and determine the target's true radial velocity.

[0092] Optionally, the matching algorithm may employ Multiple Hypothesis Testing (MHT), the principle of which is to list all possible fuzzy velocity combinations and select the optimal solution using statistical methods (such as likelihood ratio testing). The steps may be: 1) Generate a set of candidate velocities for each wavelength; 2) Find the optimal match (e.g., minimum mean square error) between candidate velocities of different wavelengths; 3) Combine other information (such as the target motion model) to filter the true velocity.

[0093] Taking the first pulse repetition frequency PRF1 as an example, the method for calculating the possible velocity v of the target includes:

[0094] When the phased array radar system transmits the carrier frequency transmission signal with the first transmission wavelength λ1

[0095] If the apparent velocity of the target is v0 > 0, then the possible velocities v are:

[0096] ν = v0 or i = 1 or 2;

[0097] If the target apparent velocity v0 < 0, the possible velocity v is:

[0098] ν = v0 or i = 1 or 2;

[0099] When the phased array radar system transmits a carrier frequency transmission signal with the second transmission wavelength λ2,

[0100] If the target apparent velocity v0 > 0, the possible velocity v is:

[0101] ν = v0 or i = 1 or 2;

[0102] If the target apparent velocity v0 < 0, the possible velocity v is:

[0103] ν = v0 or i = 1 or 2.

[0104] On the other hand, the basic premise for implementing this method is to ensure that the echo signals of both working wavelengths can be effectively detected. For the case of a single pulse repetition frequency, when a target is detected / detected using only one transmission wavelength at the same pulse repetition frequency, the corresponding target apparent velocity v0 can be obtained by adjusting (for example, appropriately reducing) the detection sensitivity threshold / limit of the other transmission wavelength.

[0105] S5. Perform one-dimensional range deblurring processing to obtain the target true range R r .

[0106] Specifically, performing range deblurring processing includes: calculating the ambiguity order M based on the leading edge times t1 and t2 of the pulse echo signals during the coherent processing periods of the first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2 at the same transmission wavelength, and then solving for the target true range R r .

[0107] Optionally, the calculation method of the ambiguity order M, that is, the ambiguity number, includes:

[0108] When t1 < t2:

[0109]

[0110] When t1 > t2:

[0111]

[0112] When t1 = t2, M = 0.

[0113] Calculate the target true range R according to the ambiguity order Mr The true distance R of the target r The calculation formula is:

[0114] R r = c / 2×(t1+M×PRT1) or R r = c / 2×(t2+M×PRT2)

[0115] Where c is the speed of light, and the formula for calculating the true distance R of the target is determined by whether the reference repetition frequency for calculating the ambiguity order M is the first pulse repetition frequency PRF1 or the second pulse repetition frequency PRF2. r .

[0116] S6, Output the target's true speed and true distance R r .

[0117] As described above, the dual-repetition-frequency phased array radar deblurring method of the present invention achieves independent processing of velocity deblurring and range deblurring by configuring dual carrier frequencies for each repetition frequency in the phased array radar system. Specifically, the present invention first uses dual carrier frequencies at the same repetition frequency to complete velocity deblurring, and then uses dual repetition frequencies for deblurring processing in the one-dimensional range domain, thereby effectively improving the accuracy of multi-target pairing and significantly reducing ghosting interference generated by the overlap algorithm.

[0118] In summary, compared with traditional coincidence algorithms, the phased array radar deblurring method based on dual repetition frequencies of this invention separates the velocity deblurring and range deblurring processes by introducing a dual carrier frequency design for each repetition frequency. On the one hand, it alleviates the pairing problem and ghosting problem existing in the two-dimensional deblurring of the coincidence algorithm, and on the other hand, it significantly reduces the spatial filling time of the phased array radar and improves the robustness of target deblurring.

[0119] Furthermore, the dual-carrier frequency design proposed in this invention effectively overcomes the technical difficulties in the allocation of spatiotemporal resources for phased array radar, and achieves efficient utilization of system resources.

[0120] Furthermore, the probabilistic optimization-based design method of this invention significantly enhances the reliability of the target defuzzification process while maintaining a low false alarm rate, and improves the system's performance in complex environments.

[0121] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0122] In the description of this invention, it should be understood that the terms "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0123] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0124] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0125] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for deambiguity resolution in phased array radar based on dual repetition frequencies, characterized in that, Include: A dual-repetition carrier frequency transmission signal is selected, which must simultaneously meet the requirements of unambiguous range detection, unambiguous velocity detection, and blind zone constraint. The two pulse repetition frequencies used for unambiguity resolution at a certain wavelength are set as the first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2. For each pulse repetition frequency, the phased array radar system uses two carrier frequency transmission signals, and the wavelengths corresponding to the two carrier frequency transmission signals are the first transmission wavelength λ1 and the second transmission wavelength λ2, respectively. The pulse transmission timing is determined, which includes four coherent processing time periods. The order of the transmission signal parameters in each time period is (PRF1, λ1), (PRF1, λ2), (PRF2, λ1) and (PRF2, λ2). For the echo signals of the coherent processing time corresponding to the first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2, velocity deblurring processing is performed to obtain the true velocity of the target. Perform distance deblurring to obtain the true target distance R. r ; Output the target's true velocity and true distance R. r .

2. The phased array radar deambiguation method based on dual repetition frequency as described in claim 1, characterized in that, The unambiguous distance detection requirement and the unambiguous velocity detection requirement are expressed as follows: Wherein, the symbol (·) represents the least common multiple operation, c represents the speed of light, Ru is the unambiguous detection range required by the phased array radar system, and Vu is the unambiguous detection speed required by the phased array radar system. The blind zone constraint requirements include: (1) The target velocity must not be blurred into the main lobe clutter region. The first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2 must satisfy the following constraints: Based on the above formula, the minimum value of the pulse repetition frequency can be obtained, where V represents the satellite's orbital velocity, θ is the 3dB beamwidth of the radar azimuth antenna, and v r_max The target's maximum radial velocity relative to the radar; (2) Ensure that the main lobe of the signal is not blurred in distance. If distance blur cannot be completely avoided, select a smaller first pulse repetition frequency PRF1 and second pulse repetition frequency PRF2 to reduce the number of distance blurs in the main lobe of the transmitted pulse signal. The coherent processing interval of each coherent processing period must be kept consistent.

3. The phased array radar deambiguation method based on dual repetition frequency as described in claim 1, characterized in that, During velocity deambiguation processing, the phased array radar system adopts a dual-carrier frequency alternating transmission mode according to a pre-set pulse transmission sequence. It utilizes the velocity deambiguation of two different carrier frequency transmission signals with the same pulse repetition frequency. The velocity deambiguation includes: In the first transmission wavelength λ1 signal processing stage, the pulse echo signal of the first transmission wavelength λ1 is used to detect the target, obtain the apparent velocity v0 of the target, and calculate the possible velocity v of the target based on the apparent velocity v0. In the second transmission wavelength λ2 signal processing stage, the pulse echo signal of the second transmission wavelength λ2 is used to detect the target, obtain the apparent velocity v0 of the target, and calculate the possible velocity v of the target based on the apparent velocity v0. Multi-wavelength data velocity cross-validation processing involves cross-validating the possible velocity v sets obtained from two different transmission wavelengths, combining the possible velocities v obtained from different transmission wavelengths, applying an overlap algorithm to de-ambiguate, and determining the true velocity of the target.

4. The phased array radar deambiguation method based on dual repetition frequency as described in claim 3, characterized in that, Taking the first pulse repetition frequency PRF1 as an example, the method for calculating the possible velocity v of the target includes: When the phased array radar system transmits a carrier frequency signal with a first transmission wavelength λ1, if the target's apparent velocity v0 > 0, then the possible velocity v is: ν = v0 or i = 1 or 2; If the target apparent velocity v0 < 0, the possible velocity v is: ν = v0 or i = 1 or 2; When the phased array radar system transmits a carrier frequency transmission signal with a second transmission wavelength λ2, if the target apparent velocity v0 > 0, the possible velocity v is: ν = v0 or i = 1 or 2; If the target apparent velocity v0 < 0, the possible velocity v is: ν = v0 or i = 1 or 2.

5. The phased array radar ambiguity resolution method based on dual pulse repetition frequencies according to claim 3, wherein: When only one transmission wavelength detects a target at a single pulse repetition frequency, the corresponding target apparent velocity v0 is obtained by adjusting the detection threshold of the other transmission wavelength.

6. The phased array radar deambiguation method based on dual repetition frequency as described in claim 1, characterized in that, The two carrier frequency transmission signals corresponding to the same pulse repetition frequency need to satisfy: Wherein, the center frequencies of the two carrier frequency transmitted signals are the first center frequency f1 and the second center frequency f2, respectively, B represents the spectral width of the transmitted signal, and ν r_min CPI represents the minimum target velocity that the phased array radar system can identify, and CPI represents the phased processing interval for each phased processing period.

7. The deambiguation method for phased array radar based on dual repetition frequencies as described in claim 1, characterized in that, Performing range ambiguity resolution processing includes: Based on the leading edge times t1 and t2 of the pulse echo signals during the coherent processing period of the first pulse repetition frequency PRF1 and the second pulse repetition frequency PRF2 at the same transmission wavelength, the ambiguity order M is calculated, and then the true target distance R is obtained. r .

8. The phased array radar deambiguation method based on dual repetition frequency as described in claim 7, characterized in that, The calculation method of the ambiguity order M includes: When t1 < t2: When t1 > t2: When t1 = t2, M = 0.

9. The phased array radar deambiguation method based on dual repetition frequencies as described in claim 7, characterized in that, The true distance to the target R r The calculation formula is: R r = c / 2×(t1+M×PRT1) or R r = c / 2×(t2+M×PRT2) Where c is the speed of light.

10. The deambiguation method for phased array radar based on dual repetition frequencies as described in claim 1, characterized in that, Before performing velocity ambiguity resolution processing, it also includes: Pulse compression, Doppler filtering processing, and phase adjustment.

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