A signal optimization method and apparatus

Abstract

The application relates to a signal optimization method and device, which comprises the following steps: determining the pulse width required by an optimized signal according to the observable area of a radar; obtaining the residual effective time of the radar according to the pulse width required by the optimized signal; determining the elevation angle range corresponding to a supplementary area according to the residual effective time; modulating the elevation angle range corresponding to the supplementary area into a supplementary sub-pulse, splicing the supplementary sub-pulse and the original transmission signal in the time domain to obtain an optimized transmission signal; and obtaining an optimized echo signal according to the optimized transmission signal. Through the above technical scheme, the limited pulse energy can be accurately positioned to the observable area by analyzing the observable area of the radar; and the residual effective time is distributed to the supplementary area by adjusting the frequency domain, so that the optimized transmission signal and echo signal are obtained, and further imaging can be performed according to the optimized echo signal, so that the system resources are optimized and a larger effective imaging width is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radar signal processing, in particular to a signal optimization method and device. BACKGROUND

[0002] High-Resolution Wide-Swath (HRWS) has attracted extensive attention in recent years due to its advantages of high resolution and wide image swath. In co-sited radar systems, the inability to receive signals during transmission results in certain areas (distance blind area) being unable to be imaged. In the case of a relatively narrow imaging range, the influence of the distance blind area can be avoided by appropriate Pulse Repetition Frequency (PRF) design. However, due to the large beam coverage, the imaging distance blind area in Time Diverse Array-Synthetic Aperture Radar (TDA-SAR) cannot be avoided, and this problem will become more serious under high duty cycle conditions. In addition, existing frequency scanning radar imaging methods ignore the influence of the distance blind area and directly design signals according to the original desired imaging area. This results in a portion of the radar energy being allocated to the distance blind area, thereby causing waste of the limited energy and time resources of the radar system. SUMMARY

[0003] In order to solve the above problems existing in the prior art, the present application provides a signal optimization method and device.

[0004] According to a first aspect of an embodiment of the present application, a signal optimization method is provided, the method comprising:

[0005] determining the pulse width required for the optimized signal according to the observable area of the radar;

[0006] obtaining the remaining effective time of the radar according to the pulse width required for the optimized signal;

[0007] determining the elevation angle range corresponding to the supplementary area according to the remaining effective time;

[0008] after modulating the elevation angle range corresponding to the supplementary area into a supplementary sub-pulse, splicing the supplementary sub-pulse and the original transmitted signal in the time domain to obtain an optimized transmitted signal;

[0009] obtaining an optimized echo signal according to the optimized transmitted signal.

[0010] Optionally, before the pulse width required for the optimized signal is determined according to the observable area of the radar, the method further comprises:

[0011] obtaining a PRI from the zebra map of the radar;

[0012] obtaining a number of delayed pulses of a transmit pulse relative to the target according to the PRI;

[0013] obtaining a rising edge time of a return signal of the target according to the number of delayed pulses;

[0014] determining an observable region according to the rising edge time.

[0015] Optionally, the determining of a pulse width required by an optimized signal according to the observable region of the radar comprises:

[0016] obtaining a range frequency bandwidth of the observable region according to the distance frequency of the observable region;

[0017] obtaining a required time of the observable region according to the range frequency bandwidth of the observable region;

[0018] obtaining a pulse width required by an optimized signal according to the required time of the observable region.

[0019] Optionally, the determining of a corresponding elevation angle range of a supplementary region according to the remaining effective time comprises:

[0020] obtaining a corresponding supplementary signal bandwidth according to the remaining effective time;

[0021] determining a corresponding elevation angle range of the supplementary region according to the supplementary signal bandwidth.

[0022] Optionally, the optimized transmit signal is represented as follows:

[0023]

[0024] wherein s mnew (t) represents the optimized transmit signal, t represents a fast time, τ m represents a time delay of an mth transmit element of the radar, T p,i represents a required time of an ith section of the observable region, i = 1, …, I, I represents a total number of sections of the observable region, rect(·) represents a rectangular window function, exp(·) represents an exponential function, j represents an imaginary unit, T p represents a pulse length, f c represents a carrier frequency, μ represents a frequency modulation rate;

[0025]

[0026] wherein T p,q represents a required time of an qth section of the observable region;

[0027]

[0028] wherein f rb,i represents the start distance frequency of the i-th segment of the observable area.

[0029] Optionally, the optimized echo signal is represented as follows:

[0030]

[0031] wherein y r (t,t k ) represents the optimized echo signal, M represents the total number of transmitting elements of the radar, s mnew,i represents the optimized transmitting signal of the i-th segment of the observable area, τ tr,m represents the time delay between the target, the m-th transmitting element and the receiving element.

[0032] Optionally, the signal optimization method further comprises:

[0033] converting the optimized echo signal to a distance frequency domain to obtain an optimized echo signal in the distance frequency domain;

[0034] The optimized echo signal in the distance frequency domain is represented as follows:

[0035]

[0036] wherein y r (f r ,t k ) represents the optimized echo signal in the distance frequency domain, fr represents the distance frequency, represents the radar scanning pattern, B wi represents the range frequency bandwidth of the i-th segment of the observable area, f re,i represents the end distance frequency of the i-th segment of the observable area.

[0037] Optionally, the supplementary signal bandwidth is represented as follows:

[0038] B rest = μ·T p,I+1 ;

[0039] wherein B rest represents the supplementary signal bandwidth, μ represents the frequency modulation rate, T p,I+1 represents the remaining effective time, T p,I+1 = T p -T p_new , T p represents the pulse length, T p_newrepresents a pulse width required by the optimized signal.

[0040] According to a second aspect of the embodiments of the present application, a signal optimization device is provided, the device comprising:

[0041] a pulse width determination module configured to determine a pulse width required by an optimized signal according to an observable area of a radar;

[0042] an effective time determination module configured to obtain a residual effective time of the radar according to the pulse width required by the optimized signal;

[0043] an elevation angle determination module configured to determine an elevation angle range corresponding to a supplementary area according to the residual effective time;

[0044] a transmission signal optimization module configured to modulate the elevation angle range corresponding to the supplementary area into a supplementary sub-pulse, and splice the supplementary sub-pulse and an original transmission signal in a time domain to obtain an optimized transmission signal;

[0045] a return signal optimization module configured to obtain an optimized return signal according to the optimized transmission signal.

[0046] The technical solutions provided by the present application can include the following beneficial effects:

[0047] Through the above technical solutions, the original transmission signal is optimized into a signal with a specific time-frequency structure by analyzing the observable area of the radar, so that the limited pulse energy can be accurately positioned to the observable area; and under the constraint of maintaining the system duty cycle, the residual effective time is allocated to the supplementary area by adjusting the frequency domain, and then the optimized transmission signal and return signal are obtained, and further imaging can be performed according to the optimized return signal, thereby realizing the optimization of system resources and a larger effective imaging width.

[0048] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0049] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, and are used together with the following specific embodiments to explain the present application, but do not constitute a limitation of the present application. In the drawings:

[0050] Figure 1 is a schematic diagram of the geometric relationship between a conventional signal model of a forward-looking TDA-SAR radar platform and a target according to an exemplary embodiment.

[0051] Figure 2 is a flowchart of a signal optimization method according to an exemplary embodiment.

[0052] Figure 3 This is a schematic diagram illustrating an optimized transmission signal according to an exemplary embodiment.

[0053] Figure 4 This is a schematic diagram illustrating the geometric relationship between the front-side-looking TDA-SAR radar platform and the target in this invention, according to an exemplary embodiment.

[0054] Figure 5a This is a schematic diagram illustrating an optimized echo signal in the range frequency domain according to an exemplary embodiment.

[0055] Figure 5b This is a schematic diagram illustrating the beam main lobe coverage angle corresponding to an optimized echo signal in the range-frequency domain, according to an exemplary embodiment.

[0056] Figure 6a This is a schematic diagram illustrating the simulation results of a raw echo signal according to an exemplary embodiment.

[0057] Figure 6b This is a schematic diagram illustrating the simulation results of a raw echo signal in the distance-frequency domain according to an exemplary embodiment.

[0058] Figure 6c This is an example illustrating a situation where t k Distance-frequency profile when 0 = 0.

[0059] Figure 6d This is a schematic diagram illustrating the separation result of target 5 in the range frequency domain according to an exemplary embodiment.

[0060] Figure 6e This is a schematic diagram illustrating the imaging result of target 3 according to an exemplary embodiment.

[0061] Figure 6f This is a schematic diagram illustrating the imaging result of target 4 according to an exemplary embodiment.

[0062] Figure 6g This is a schematic diagram illustrating the imaging result of target 5 according to an exemplary embodiment.

[0063] Figure 6h This is a schematic diagram illustrating the imaging result of target 6 according to an exemplary embodiment.

[0064] Figure 7 This is a block diagram illustrating a signal optimization device according to an exemplary embodiment. Detailed Implementation

[0065] To facilitate understanding of the present invention, a brief description of the prior art and the inventive concept of the present invention will be provided first.

[0066] In SCORE (Specific Target and Environment Detection Mode in Synthetic Aperture Radar) mode, the radar transmits a wide elevation beam and receives a narrow beam, effectively suppressing range ambiguity. In addition, the equivalent phase center method effectively improves the signal sampling rate using azimuth multi-channel, thereby reducing the PRF requirement of the system and enhancing the width of the unambiguous imaging. In addition, Multiple-Input Multiple-Output-Synthetic Aperture Radar (MIMO-SAR) converts the orthogonal signals between multiple channels to further expand the imaging width. Based on the system degrees of freedom (such as space, time, frequency, and coding dimensions), Waveform Diversity Array (WDA) can more effectively separate the range ambiguity clutter. However, due to the limitations of non-ideal orthogonal waveforms, the imaging performance of MIMO-SAR is poor.

[0067] To avoid the influence of MIMO waveforms, HRWS imaging based on coherent waveforms has achieved remarkable results. Among them, the Multi-Frequency Sub-Pulse (MFSP) method divides the pulse into multiple sub-pulses, which are separated in the range frequency domain and pointed to different areas, achieving ultra-wide swath imaging. Unlike the spatially discrete scanning regime of sub-pulse, the elevation time diversity array radar introduces time delay between channels, enabling the radar to achieve continuous beam scanning within a single pulse and achieve wide coverage in the range direction.

[0068] Due to the dispersion of energy in a single pulse over a large area, TDA-SAR requires a large transmit signal bandwidth to ensure image quality, which also means a higher duty cycle, and the problem of imaging distance blind area is more serious, thereby causing waste of limited energy and time resources of the radar system.

[0069] Figure 1 is a schematic diagram of the geometric relationship between a conventional signal model and a target of an elevation TDA-SAR radar platform according to an exemplary embodiment, as shown in FIG. 1, the radar uses M transmitting units in the elevation direction, and synthesizes a sub-array when receiving. The inclination angle of the array installation is The transmission signal delay between adjacent array elements is Δτ, and the time delay of the mth element is represented as τ m = (m - (M + 1) / 2) Δτ, assuming that there is a target in the scene with coordinates (x0, y0) and an elevation angle of θ, the signal received by the target can be represented as:

[0070]

[0071] where t is fast time, T p is pulse length, μ is frequency modulation rate, c is light speed, f c is carrier frequency, rect(·) represents fast time window function; is the two-way time delay between the target, the mthtransmitting array element and the receiving array element, and R r (t k ) can be expressed as:

[0072]

[0073] where R B represents the closest slant range between the radar and the target, v represents the speed of the carrier, x0represents the transmitting slant distance between each array element, is the elevation angle of the target. After down-converting the echo and transforming it to the range frequency domain, we can get:

[0074]

[0075] where, is the TDA radar scanning pattern, which can be expressed as:

[0076]

[0077] From the above formula, it can be seen that the angle of the main lobe is coupled with the range frequency, that is, the beam angle changes with the range frequency. When transmitting signals with different range frequencies within the pulse duration, the beam will be scanned accordingly. By relying on the frequency scanning characteristics, wide beam coverage is achieved. In addition, it can be deduced that the range frequency corresponding to a certain main lobe angle is as shown in the following formula:

[0078]

[0079] The two zeros corresponding to the main lobe can be expressed as:08 / 5

[0080]

[0081] The effective range bandwidth of the target is expressed as:

[0082]

[0083] Based on the intra-pulse beam scanning characteristics and considering the above frequency coupling relationship, a corresponding bandwidth range imaging framework is designed, ignoring the distance blind area factor. In practice, the distance blind area cannot be avoided, which will lead to the waste of time and frequency resources. Therefore, the present application proposes a signal optimization method to solve the technical problem.

[0084] Figure 2 is a flowchart of a signal optimization method according to an exemplary embodiment, as shown inFigure 2 As shown, the method includes the following steps:

[0085] S101. Determine the pulse width required for optimizing the signal based on the radar's observable area.

[0086] Optionally, prior to S101, the method may further include:

[0087] PRI is obtained from the zebra pattern of radar;

[0088] The number of delay pulses relative to the target's transmitted pulse is obtained from PRI;

[0089] The rise time of the target's echo signal is obtained from the number of delayed pulses;

[0090] The observable region is determined based on the rise time.

[0091] It is understandable that we assume the lower field of view range of the initial desired imaging region is [θ]. near ,θ far The system protection time is T. g The desired distance resolution and azimuth resolution are then expressed as ρ. r , ρ a We can select a suitable PRI by considering the zebra diagram of the radar system. Then, the delay pulse number relative to the target's transmitted pulse can be expressed as:

[0092]

[0093] Where floor(·) represents rounding down to the nearest integer;

[0094] The rise time of the target echo can be expressed as:

[0095]

[0096] when satisfy When the relationship is such that the corresponding region is the observable region, then the downward elevation angle of the observable region can be determined, denoted as ;

[0097] θ i ∈(θ b,i ,θ e,i );

[0098] Where, θ i (i = 1, ..., I) represents the angle within the i-th segment of a continuously observable region, θ b,i and θ e,i Let represent the starting angle and ending angle of the i-th segment of the observable region, respectively.

[0099] Optionally, S101 can include:

[0100] According to the distance frequency of the observable region, the range frequency bandwidth of the observable region is obtained;

[0101] According to the range frequency bandwidth of the observable region, the required time of the observable region is obtained;

[0102] According to the required time of the observable region, the pulse width required by the optimized signal is obtained.

[0103] It can be understood that the distance frequency mapped to the ith segment of the observable region can be derived as:

[0104] f ri ∈(f rb,i ,f re,i );

[0105] Where f rb,i and f re,i represent the start and end distance frequencies of the ith segment of the observable region, respectively. The range frequency bandwidth of the region can be represented as B wi = f re,i -f rb,i , the time required by the ith segment of the observable region can be represented as T p,i =B wi / k r , Figure 3 is a schematic diagram of transmitting signal optimization according to an exemplary embodiment. As shown in Figure 3 After calculating the time width corresponding to all effective regions of the observable region and the distance frequency mapping region, the corresponding sub-pulse signals in the fast time domain are concatenated to construct a new signal, which only contains the distance frequency mapped to the observable region. At this time, the pulse width required by the optimized signal can be represented as:

[0106]

[0107] S102, according to the pulse width required by the optimized signal, the remaining effective time of the radar is obtained.

[0108] S103, according to the remaining effective time, the elevation angle range corresponding to the supplementary region is determined.

[0109] It can be understood that S103 can include:

[0110] According to the remaining effective time, the corresponding supplementary signal bandwidth is obtained;

[0111] According to the supplementary signal bandwidth, the elevation angle range corresponding to the supplementary region is determined.

[0112] Therefore, compared to the original system, the proposed method can effectively reduce the required duty cycle while maintaining the same effective illumination area. By maintaining the radar's duty cycle, the remaining effective time of the radar is given by the following formula:

[0113] T p,I+1 =T p -T p_new ;

[0114] Then, this energy is allocated to the supplementary region, increasing the effective imaging strip width. At this point, the corresponding supplementary signal bandwidth is:

[0115] Brest = μ·(Tp-Tp_new);

[0116] Where μ represents the modulation frequency, T p T represents the pulse length. p_new This indicates the pulse width required to optimize the signal.

[0117] Assume the initial pitch angle of the supplementary region is θ rest1 The corresponding elevation angle is It is worth noting that, due to the effective frequency bandwidth increasing... The decrease in θ leads to an increase in θ; therefore, to ensure that the supplementary region still satisfies the distance resolution constraint, a value satisfying θ should be selected. rest1 <θ near Relationship To ensure effective illumination at this angle, the initial range frequency f of this region is... rb,I+1 This is calculated using a traditional model. The upper limit of the distance frequency in the supplementary region is f. re,I+1 =f rb,I+1 +B rest Then, the other angular boundary of the supplementary region The following relationship must be satisfied:

[0118]

[0119] Therefore, the range of elevation angles corresponding to the supplementary region can be expressed as:

[0120] S104. After modulating the elevation angle range corresponding to the supplementary region into a supplementary sub-pulse, the supplementary sub-pulse and the original transmitted signal are spliced ​​together in the time domain to obtain the optimized transmitted signal.

[0121] Alternatively, the optimized transmitted signal can be represented as follows:

[0122]

[0123] Among them, s mnew (t) represents the optimized transmitted signal, t represents the fast time, and τ represents the fast time. mdenotes the time delay of the mth transmit element of the radar, T p,i denotes the required time of the ith segment of the observable region, i = 1, …, I, I denotes the total number of segments of the observable region, rect(·) denotes a rectangular window function, exp(·) denotes an exponential function, j denotes an imaginary unit, T p denotes the pulse length, f c denotes the carrier frequency, μ denotes the frequency modulation rate;

[0124]

[0125] wherein T p,q denotes the required time of the qth segment of the observable region;

[0126]

[0127] wherein f rb,i denotes the start range frequency of the ith segment of the observable region.

[0128] S105, obtaining an optimized echo signal according to the optimized transmit signal.

[0129] Optionally, the optimized echo signal is represented as follows:

[0130]

[0131] wherein y r (t, t k ) denotes the optimized echo signal, M denotes the total number of transmit elements of the radar, s mnew,i denotes the optimized transmit signal of the ith segment of the observable region, τ tr,m denotes the time delay between the target, the mth transmit element and the receive element.

[0132] Optionally, the method can further comprise:

[0133] converting the optimized echo signal to a range frequency domain to obtain an optimized echo signal in the range frequency domain;

[0134] The optimized echo signal in the range frequency domain is represented as follows:

[0135]

[0136] wherein y r (f r , t k ) denotes the optimized echo signal in the range frequency domain, fr denotes a range frequency, denotes the radar scanning pattern, B wi denotes the range frequency bandwidth of the ith segment of the observable region, f re,iEnd range frequency of the i-th segment representing the observable region.

[0137] By the above design, the limited radar energy can be allocated to the specific supplementary region, Figure 4 is a schematic diagram of the geometric relationship between the TDA-SAR radar platform and the target in the present application according to an exemplary embodiment, as shown in Figure 4 As shown, correspondingly, compared with the original imaging system, the optimized echo signal obtained by the flexible energy allocation strategy can effectively expand the imaging width of the system.

[0138] In an embodiment, the angular beam coupling characteristic enables it to separate the echoes from different regions in the range frequency domain. To achieve this, a specific bandpass filter can be constructed in the range frequency domain, which is represented as follows:

[0139]

[0140] Since the echo signals from different regions only undergo bandpass filtering and windowing processing in the range frequency domain, the conventional imaging algorithm is still effective. Therefore, the range Doppler imaging algorithm can be used to process the bandpass filtered data, and after range compression, range cell migration correction and azimuth angle matching, the imaging result can be represented as:

[0141]

[0142] Where, Δf a is the Doppler bandwidth of the target. Then, the bandpass filtering and imaging process are applied to other targets located in different regions, and finally the explicit imaging result can be obtained.

[0143] In an embodiment, the effectiveness of the present application is verified by simulation, assuming that the radar works in the side-looking mode, and other system parameters are listed in Table 1.

[0144] Table 1

[0145]

[0146] Then the range blind area map is obtained, and the distance blind area is inevitable in the required large coverage area. After considering the requirement of azimuth resolution, the PRF is selected as 3395 Hz. Therefore, the top view angle of the observable region is θ1∈(42°, 44.395°), θ2∈(45.55°, 47.77°), θ3∈(48.74°, 50°), which accounts for 73.44% of the total observation area. If the original linear frequency modulation (LFM) signal is transmitted, a part of the energy will be wasted due to the fact that the echo data of part of the region cannot be received.

[0147] To solve this problem, the corresponding distance-frequency discrete observable region can be obtained as f r1 ∈(-223.05,-168.72)MHz, f r2 ∈(-125.67,-250.59)MHz, f r3 ∈(29.25,144.75)MHz, corresponding to the length of the sub-pulse T p,i =[8.469,16.017,18.386]μs,(i=1,2,3).T p,4 and B rest are 36.476μs, 229MHz. The initial downward angle of the supplementary region is selected as 39°, and the corresponding initial distance frequency is 271.04MHz. Therefore, the downward angle corresponding to the extended imaging range can be obtained as θ4∈(35.625°,39°).

[0148] Figure 5a is a schematic diagram of an optimized echo signal in a distance-frequency domain according to an exemplary embodiment, Figure 5b is a schematic diagram of a beam main lobe coverage angle corresponding to the optimized echo signal in a distance-frequency domain according to an exemplary embodiment, as Figure 5a shown, the designed echo signal is divided into four discrete distance-frequency support regions in the distance-frequency domain, and each frequency domain region corresponds to one of the four observable regions. In addition, the beam pattern corresponding to the optimized signal is obtained, as Figure 5b shown. The design of the time-frequency optimized signal can flexibly allocate limited energy to different observable regions, thereby improving the energy utilization efficiency of the radar system.

[0149] To further illustrate the effectiveness of the method, six targets can be set. Figure 6a is a simulation result schematic diagram of an original echo signal according to an exemplary embodiment, Figure 6b is a simulation result schematic diagram of an original echo signal in a distance-frequency domain according to an exemplary embodiment, Figure 6c is a distance-frequency profile diagram when t k =0 according to an exemplary embodiment, Figure 6d is a separation result schematic diagram of target 5 in a distance-frequency domain according to an exemplary embodiment, Figure 6e is an imaging result schematic diagram of target 3 according to an exemplary embodiment, Figure 6f is an imaging result schematic diagram of target 4 according to an exemplary embodiment, Figure 6g is an imaging result schematic diagram of target 5 according to an exemplary embodiment, Figure 6his a schematic diagram of imaging results of target 6 according to an exemplary embodiment. The angles of the following five targets are 45.009°, 48.285°, 46.697°, 49.857°, 43.102° and 38°, respectively. The first two targets are located in the range blind zone. The third, fourth and fifth targets are located in the observable region, and the three targets are located in different range ambiguity zones. The fifth target is located in the supplementary region. Figure 6a Echo targets 1 and 2 show that the original echo signals cannot be effectively received because they are located in the range blind zone. It should be noted that even if the theoretical envelope rising edge is only 25 meters apart for targets 3, 4 and 5, the distance modulation caused by the transmission beam pattern is observed, and different targets show obvious distance differences. From Figure 6b It can be seen from that after the echo signal is converted into the range frequency domain, targets at different distances occupy different range-frequency regions. This feature can gap ambiguity signals in the range frequency domain. Because target 4 is located at the edge of the scene. Figure 6c The range-frequency distribution of the azimuth center time is shown, and the frequency domain support region is aligned with the theoretical analysis. Subsequently, a corresponding range-frequency bandpass filter can be constructed to separate the echo, Figure 6d The separation result of target 5 is shown. After bandpass filtering, the data of target 5 is retained. Other targets are suppressed. Similarly, all these targets can be separated by constructing a corresponding filter. Next, an imaging algorithm is used for imaging processing. Figure 6e - Figure 6h The imaging results of targets 3-6 are shown. After signal optimization design, the pulse energy is effectively allocated to the observable region. The coverage range can be expanded to the region corresponding to target 6, thereby increasing the imaging width. However, due to the waste of energy in the range blind zone and the fact that target 6 is not in the originally specified imaging region, the traditional TDA system cannot observe the region where target 6 is located.

[0150] The present application can flexibly allocate limited pulse energy to the observable region, effectively improve the utilization efficiency of radar resources, and increase the imaging width of the optimized echo signal. The effectiveness of the proposed method is verified by simulation experiments.

[0151] Figure 7 is a block diagram of a signal optimization device according to an exemplary embodiment. Referring to Figure 7 The signal optimization device 700 can include.

[0152] The pulse width determination module 701 is configured to determine the pulse width required by the optimized signal according to the observable region of the radar.

[0153] The effective time determination module 702 is configured to obtain the remaining effective time of the radar according to the pulse width required by the optimized signal.

[0154] An elevation angle determination module 703 is configured to determine an elevation angle range corresponding to the supplementary region according to the remaining valid time;

[0155] A transmission signal optimization module 704 is configured to modulate the elevation angle range corresponding to the supplementary region into a supplementary sub-pulse, and splice the supplementary sub-pulse and the original transmission signal in the time domain to obtain an optimized transmission signal after the splicing;

[0156] An echo signal optimization module 705 is configured to obtain an optimized echo signal according to the optimized transmission signal.

[0157] As to the apparatus in the above-mentioned embodiments, the specific manners in which the various modules perform operations have been described in detail in the embodiments of the method, and thus will not be described in detail here.

[0158] The preferred embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited to the specific details in the above-mentioned embodiments. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application.

[0159] In addition, it should be noted that each specific technical feature described in the above-mentioned specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present application will not make any further description on various possible combinations.

[0160] In addition, any combination of the various different embodiments of the present application can also be made, as long as it does not deviate from the technical concept of the present application, and it should also be considered as the disclosed content of the present application.

Claims

1. A signal optimization method, characterized in that, The method includes: The pulse width required to optimize the signal is determined based on the radar's observable area; The remaining effective time of the radar is obtained based on the pulse width required for optimizing the signal; The range of elevation angles corresponding to the supplementary area is determined based on the remaining effective time. After modulating the elevation angle range corresponding to the supplementary region into a supplementary sub-pulse, the supplementary sub-pulse and the original transmitted signal are spliced ​​together in the time domain to obtain the optimized transmitted signal; The optimized echo signal is obtained based on the optimized transmitted signal; The optimized transmission signal is represented as follows: ； in, This refers to the optimized transmission signal. Indicates a fast time. Indicates radar number Time delay of each transmission element The first term representing the observable region The time required for the segment , This represents the total number of segments in the observable region. Represents a rectangular window function. Represents an exponential function. Indicates the imaginary part unit. Indicates pulse length. Indicates the carrier frequency. Indicates frequency modulation; ； in, The first term representing the observable region The time required for each segment; ； in, The first term representing the observable region The starting distance frequency of the segment.

2. The signal optimization method according to claim 1, characterized in that, Before determining the pulse width required to optimize the signal based on the observable area of ​​the radar, the method further includes: PRI is obtained from the zebra pattern of the radar; The number of delay pulses relative to the target's transmitted pulse is obtained based on the PRI. The rise time of the target's echo signal is obtained based on the number of delayed pulses; The observable region is determined based on the rise time.

3. The signal optimization method according to claim 1, characterized in that, Determining the pulse width required for optimizing the signal based on the radar's observable area includes: The range-frequency bandwidth of the observable region is obtained based on the distance frequency of the observable region; The required time for the observable region is obtained based on the range-frequency bandwidth of the observable region; The pulse width required to optimize the signal is obtained based on the required time in the observable region.

4. The signal optimization method according to claim 1, characterized in that, The step of determining the elevation angle range corresponding to the supplementary area based on the remaining effective time includes: The corresponding supplementary signal bandwidth is obtained based on the remaining effective time. The elevation angle range corresponding to the supplementary region is determined based on the supplementary signal bandwidth.

5. The signal optimization method according to claim 1, characterized in that, The optimized echo signal is represented as follows: ； in, This refers to the optimized echo signal. This indicates the total number of transmitting array elements of the radar. The first term representing the observable region The optimized transmission signal of the segment Indicates the goal, the first The time delay between each transmitting element and receiving element.

6. The signal optimization method according to claim 5, characterized in that, The signal optimization method further includes: The optimized echo signal is converted to the range frequency domain to obtain the optimized echo signal in the range frequency domain. The optimized echo signal in the distance-frequency domain is represented as follows: ； in, This represents the optimized echo signal in the range frequency domain. Indicates distance frequency, This indicates the radar scan pattern. The first term representing the observable region The range frequency bandwidth of the segment. The first term representing the observable region The frequency of the end distance of the segment.

7. The signal optimization method according to claim 4, characterized in that, The supplementary signal bandwidth is represented as follows: ； in, This indicates the bandwidth of the supplementary signal. Indicates frequency modulation. This indicates the remaining valid time. , Indicates pulse length. This indicates the pulse width required for the optimized signal.

8. A signal optimization device, characterized in that, The device includes: The pulse width determination module is used to determine the pulse width required to optimize the signal based on the observable area of ​​the radar. An effective time determination module is used to determine the remaining effective time of the radar based on the pulse width required for optimizing the signal; An elevation angle determination module is used to determine the elevation angle range corresponding to the supplementary area based on the remaining effective time; The transmission signal optimization module is used to modulate the elevation angle range corresponding to the supplementary region into a supplementary sub-pulse, and then splice the supplementary sub-pulse and the original transmission signal in the time domain to obtain the optimized transmission signal; An echo signal optimization module is used to obtain an optimized echo signal based on the optimized transmitted signal; The optimized transmission signal is represented as follows: ； in, This refers to the optimized transmission signal. Indicates a fast time. Indicates radar number Time delay of each transmission element The first term representing the observable region The time required for the segment , This represents the total number of segments in the observable region. Represents a rectangular window function. Represents an exponential function. Indicates the imaginary part unit. Indicates pulse length. Indicates the carrier frequency. Indicates frequency modulation; ； in, The first term representing the observable region The time required for each segment; ； in, The first term representing the observable region The starting distance frequency of the segment.

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