Remote target detection method, system and equipment using narrow pulse signal

Abstract

The invention relates to a long-distance target detection method, system and equipment using a narrow pulse signal, and the method comprises the steps: carrying out the inter-pulse phase coding of a narrow pulse through introducing an Ipaov sequence, employing the full-sampling circulation cross-correlation processing at a receiving end, enabling the maximum unambiguous distance to be expanded to N. PRI, and improving the total energy through the accumulation of N pulses, the maximum unambiguous detection distance is changed from PRI determination to CPI determination, and the maximum unambiguous detection distance can be increased by N times compared with a common high repetition frequency pulse string signal. The complete echo signal is subjected to cyclic cross-correlation processing at the receiving end instead of phase discrimination and then correlation, the maximum detection distance of the radar can be effectively improved by increasing the length of the Ipaatov sequence or properly increasing the pulse width, the low sidelobe level is achieved, false targets are avoided, the target detection accuracy is improved, and meanwhile the detection efficiency is improved. And a relatively large maximum non-blurring detection distance is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar detection, and relates to a method, system and device for detecting distant targets using narrow pulse signals. Background Art

[0002] A narrow pulse refers to a radar pulse with a pulse width below 50 nanoseconds. In radar applications, narrow pulse signals are widely used in ultra-wideband radar imaging, vital sign monitoring, ground penetrating radar and other fields due to their advantages in range resolution, Doppler tolerance and ultra-short range detection capabilities. However, in terms of the performance of detecting distant targets, according to the radar equation, the maximum operating distance of a radar is proportional to the total radiation energy that the radar can utilize. Due to the relatively narrow pulse width, the total radiation energy that a narrow pulse signal can utilize is relatively limited. Therefore, generally, a high-power (peak power exceeding hundreds of megawatts) pulse source or the use of a high pulse repetition frequency (PRF) and coherent processing is relied on to achieve the detection of distant targets.

[0003] In terms of high-power pulse sources, current advanced radar transmitter and antenna systems generally use solid-state transmitters, whose peak power is more limited compared to vacuum tube devices, and it is difficult to transmit high-power narrow pulse signals without using special designs; using a medium-high PRF mode can effectively increase the number of pulses transmitted per unit time, but at this time, range ambiguity problems may occur because the echo delay from distant targets may be longer than the pulse repetition interval (PRI).

[0004] A common way to solve range ambiguity is to use multiple coherent processing intervals (CPIs) within a single dwell time, and each CPI has a different pulse repetition frequency. By adopting a "P select H" decision, it can help determine the true range and Doppler frequency. Here, H is usually 2 or 3 PRFs, and P can be up to 8 PRFs. For example, a "8 select 2" detection decision means that only 2 out of 8 CPIs contribute energy during detection, and this strategy will be relatively inefficient in using the transmitted energy. On this basis, some scholars proposed that the initial phase of each narrow pulse signal can be encoded to mitigate range ambiguity in high PRF. By modulating the initial phase of each transmitted pulse and performing cross-correlation on the entire CPI, inter-pulse phase encoding transfers the task of pulse compression from a single long coded pulse to multiple short pulses with inter-pulse coding. At this time, the maximum unambiguous detection range is controlled by the CPI rather than the PRI, thus solving the range ambiguity problem in the high PRF mode. However, when processing the echo signal in the above research, it is necessary to perform detection, synchronization, and phase discrimination processing on each pulse separately, and then perform correlation processing on the digitized phase obtained by phase discrimination using the reference phase sequence. If a single pulse cannot be detected, subsequent synchronization and phase discrimination work cannot be carried out. Therefore, the detection probability of this method is still limited by the peak transmitted power of a single pulse and it is difficult to meet the energy requirements for long-range target detection. Summary of the Invention

[0005] Aiming at the problems existing in the above traditional technologies, the present invention proposes a long-range target detection method using narrow pulse signals, a long-range target detection system using narrow pulse signals, and a computer device, which can effectively improve the long-range target detection performance.

[0006] To achieve the above object, the embodiments of the present invention adopt the following technical solutions: On the one hand, a long-range target detection method using narrow pulse signals is provided, including the steps of: Determine the currently used pulse width within the set narrow pulse range; Select the Ipatov sequence as the inter-pulse phase encoding sequence and determine the corresponding reference sequence; Determine the pulse repetition interval according to the characteristics of the narrow pulse and the maximum detection range requirement of the radar system; Perform inter-pulse phase encoding on the narrow pulse train of the radar system according to the Ipatov sequence and the pulse repetition interval, generate the transmitted waveform within the coherent processing interval, and transmit it to the target; Perform cyclic cross-correlation processing on the complete echo signal corresponding to the transmitted waveform received by the radar system to obtain the range information of the target.

[0007] On the other hand, a long-distance target detection system using narrow pulse signals is also provided, including: A pulse width determination module for determining the currently used pulse width within a set narrow pulse range; A sequence selection module for selecting the Ipatov sequence as the inter-pulse phase coding sequence and determining the corresponding reference sequence; An interval determination module for determining the pulse repetition interval according to the characteristics of the narrow pulse and the maximum detection distance requirement of the radar system; A phase coding module for performing inter-pulse phase coding on the narrow pulse train of the radar system according to the Ipatov sequence and the pulse repetition interval, generating a transmitted waveform within the coherent processing interval and transmitting it to the target; A cyclic cross-correlation module for performing cyclic cross-correlation processing on the complete echo signal corresponding to the transmitted waveform received by the radar system to obtain the distance information of the target.

[0008] On the other hand, a computer device is also provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the above-mentioned long-distance target detection method using narrow pulse signals are implemented.

[0009] One of the above technical solutions has the following advantages and beneficial effects: The above-mentioned long-distance target detection method, system, and device using narrow pulse signals, by introducing the Ipatov sequence to perform inter-pulse phase coding on the narrow pulse and adopting full-sampling cyclic cross-correlation processing at the receiving end, extend the maximum unambiguous distance to N ·PRI, and at the same time, can N accumulate the total energy by N pulses. Therefore, it can take into account narrow pulses and long-distance detection, break through the "wide pulse - long distance" binding relationship in traditional radar design, solve the distance ambiguity problem in the high pulse repetition frequency mode, and change the determination of the maximum unambiguous detection distance from being determined by PRI to being determined by CPI. The maximum unambiguous detection distance can be increased by times compared with ordinary high pulse repetition frequency pulse train signals. By performing cyclic cross-correlation processing on the complete echo signal at the receiving end, rather than phase discrimination first and then correlation, the maximum detection distance of the radar can be effectively increased by increasing the length of the Ipatov sequence or appropriately increasing the pulse width. And by using the excellent cyclic correlation characteristics of the Ipatov sequence, low sidelobe levels are achieved and the generation of false targets is avoided, improving the accuracy of target detection. Finally, while maintaining the high range resolution of the narrow pulse signal, a relatively large maximum unambiguous detection distance is achieved, making the radar system more practical in long-distance target detection. Description of the Drawings

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0011] Figure 1 It is a schematic flowchart of a long-distance target detection method using narrow pulse signals in an embodiment; Figure 2 It is a schematic diagram of signal, reference, and cyclic cross-correlation using Ipatov 13 sequence inter-pulse coding in an embodiment; wherein, Figure 2 (a) is the signal with inter-pulse coding, Figure 2 (b) is the corresponding reference sequence, Figure 2 (c) is the result of cyclic cross-correlation; Figure 3 It is a schematic diagram of the direct correlation results corresponding to two sequences in an embodiment; wherein, Figure 3 (a) is the direct cross-correlation result of the Ipatov 13 sequence, Figure 3 (b) is the direct autocorrelation result of the Barker 13 sequence; Figure 4 It is a schematic diagram of the cyclic correlation results corresponding to two sequences in an embodiment; wherein, Figure 4 (a) is the cyclic cross-correlation result of the Ipatov 13 sequence, Figure 4 (b) is the cyclic correlation result of the Barker 13 sequence; Figure 5 It is a schematic diagram of the cyclic correlation results after taking the logarithm of the inter-pulse phase encoding using the Ipatov 13 sequence and the Barker 13 sequence respectively in an embodiment; wherein, Figure 5 (a) is the encoding cyclic correlation result of performing cyclic cross-correlation processing on the received complete echo signal when transmitting a narrow pulse signal with inter-pulse phase encoding using the Ipatov 13 sequence, Figure 5 (b) is the encoding cyclic correlation result of performing cyclic cross-correlation processing on the received complete echo signal when transmitting a narrow pulse signal with inter-pulse phase encoding using the Barker 13 sequence; Figure 6 It is a block diagram of a long-distance target detection system using narrow pulse signals in an embodiment. Detailed implementation manners

[0012] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0013] It should be noted that referring to "embodiment" in this document means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of the present invention. The phrase is shown at various positions in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art can understand that the embodiments described herein can be combined with other embodiments. The term "and / or" used in the description and appended claims of the present invention refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0014] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0015] Although radar technology using narrow pulse signals for target detection has made great progress, it is still very difficult to achieve long-range target detection. To improve the relevant capabilities of radar using narrow pulse signals for long-range target detection, it is necessary to explore the design method of narrow pulse signals and the corresponding echo signal processing algorithms to better utilize the total radiation energy of the radar and increase the maximum operating range of the radar while solving the range ambiguity problem.

[0016] In one embodiment, as Figure 1 shown, a long-range target detection method using narrow pulse signals is provided. By performing inter-pulse phase encoding on the narrow pulse sequence, the maximum unambiguous detection range is no longer limited by the PRI and inter-pulse energy accumulation can be performed, thereby achieving long-range target detection capabilities. The long-range target detection method may include the following steps S10 to S18: S10, determine the currently used pulse width within the set narrow pulse range; S12, select the Ipatov sequence as the inter-pulse phase encoding sequence and determine the corresponding reference sequence; S14, determine the pulse repetition interval according to the characteristics of the narrow pulse and the maximum detection range requirement of the radar system; S16, perform inter-pulse phase encoding on the narrow pulse train of the radar system according to the Ipatov sequence and the pulse repetition interval, generate the transmitted waveform within the coherent processing interval and transmit it to the target; S18. Perform cyclic cross-correlation processing on the complete echo signal corresponding to the transmitted waveform received by the radar system to obtain the distance information of the target.

[0017] It can be understood that the maximum detection range of the radar can be derived according to the radar equation. R max and the average transmitted power P avg 、the number of pulses within the CPI N CPI and the pulse width T p are related as shown in the following formula: (1) Since the pulse width of the narrow pulse signal is limited, in order to increase the maximum detection range, it is necessary to increase the number of pulses within the CPI. N CPI。 Reduce the PRI. Adopting a medium PRF or high PRF mode can effectively increase the number of pulses. N CPI。 However, for traditional narrow pulse radars, its maximum unambiguous detection range can be expressed as: (2) where c is the speed of light. It can be seen from the above formula (2) that when the CPI is fixed, increasing the number of pulses N CPI will limit the maximum unambiguous detection range, resulting in a serious range ambiguity problem for long-distance detection.

[0018] In this embodiment, first determine the pulse width of the narrow pulse T p , so that T p satisfies the condition of the set narrow pulse range of 10 ns ≤ T p ≤ 50 ns. According to specific application requirements and the hardware capabilities of the radar system, an appropriate pulse width T p can be selected within the above-mentioned set narrow pulse range. T p For example, but not limited to,

[0019] = 20 ns can be selected, which provides a range resolution of 3 meters while ensuring the narrow pulse LPI (Low Probability of Intercept) characteristic. N. The Ipatov sequence has ideal periodic cross-correlation characteristics. Except when the time delay is zero, the periodic cross-correlation between the sequence and its reference sequence is close to zero at other time delays, showing ideal sidelobe-free cross-correlation. Figure 2 Shows the signal (complex envelope) obtained by encoding the initial phase of a pulse train using the Ipatov 13 sequence as Figure 2 shown in (a), the corresponding reference sequence as Figure 2 shown in (b), and their cyclic cross-correlation results as Figure 2 shown in (c). To show the cyclic correlation, two consecutive CPIs of the pulse sequence, reference sequence, and correlation result of the narrow pulse train are shown. From Figure 2 it can be seen that both the sequence and the cyclic correlation result are periodic with where N also represents the number of symbols of the Ipatov sequence, represents the pulse repetition interval (PRI). Therefore, when using the inter-pulse phase encoding system, the ambiguity of the time delay changes from to , and the maximum unambiguous detection range can be increased by increasing the number of symbols N or increasing .

[0020] Next, determine the pulse repetition interval PRI. Considering the characteristics of the narrow pulse and the maximum detection range requirement of the radar system, the PRI value can be reasonably selected accordingly. For example, but not limited to, PRI = 2 μs can be selected, and at this time, the duty cycle of the radar system is 1%.

[0021] Next, the narrow pulse train of the radar system can be encoded with inter-pulse phase according to the selected Ipatov sequence and pulse repetition interval PRI to generate the transmitted waveform within the coherent processing interval (CPI). For each pulse of the narrow pulse train, its initial phase is modulated according to the value at the corresponding position of the Ipatov sequence. During the transmission of the narrow pulse train, its pulse sequence is cyclically transmitted in time sequence to meet the conditions for cyclic cross-correlation processing.

[0022] Finally, perform cyclic cross-correlation processing on the complete echo signal corresponding to the transmitted waveform received by the radar system to obtain the distance information of the target. The cyclic cross-correlation processing includes performing cyclic cross-correlation operation on the received complete echo signal and the reference sequence to obtain the correlation function.

[0023] The above method for detecting distant targets using narrow pulse signals, by introducing the Ipatov sequence to perform inter-pulse phase encoding on the narrow pulse and adopting full-sampling cyclic cross-correlation processing at the receiving end, while expanding the maximum unambiguous distance to , can also NPulse accumulation enhances the total energy, thus enabling both narrow pulses (high resolution) and long-distance detection, breaking through the "wide pulse - long distance" binding relationship in traditional radar designs, solving the range ambiguity problem in high pulse repetition frequency (PRF) modes, and changing the determination of the maximum unambiguous detection range from being determined by the PRI to being determined by the coherent processing interval (CPI). The maximum unambiguous detection range can be increased N times compared to ordinary high-PRF pulse train signals. By performing cyclic cross-correlation processing on the complete echo signal at the receiving end instead of phase discrimination followed by correlation, the maximum detection range of the radar can be effectively increased by increasing the length of the Ipatov sequence or appropriately increasing the pulse width. Utilizing the excellent cyclic correlation characteristics of the Ipatov sequence, low sidelobe levels are achieved and the generation of false targets is avoided, improving the accuracy of target detection. Ultimately, while maintaining the high range resolution of narrow pulse signals, a large maximum unambiguous detection range is achieved, making the radar system more practical for long-distance target detection.

[0024] In the present invention, the maximum unambiguous detection range can be determined by the following formula: (3) where c is the speed of light, N is the length of the Ipatov sequence, and PRI is the pulse repetition interval. For example, when using a ternary Ipatov sequence with N = 183 and PRI = 2 μs, the maximum unambiguous detection range of the radar system is: (4) The above distance is sufficient to meet the general long-distance detection requirements.

[0025] In one embodiment, the Ipatov sequence is a binary Ipatov sequence, and the reference sequence is a sequence that does not match the binary Ipatov sequence.

[0026] Optionally, if the selected Ipatov sequence is a binary Ipatov sequence, the corresponding reference sequence is a sequence that does not match the binary Ipatov sequence; preferably, the peak of the correlation function is enhanced by increasing the code length N of the Ipatov sequence, thereby increasing the maximum detection range of the radar.

[0027] In one embodiment, the Ipatov sequence is a ternary Ipatov sequence, and the reference sequence is the same as the pulse sequence of the narrow pulse train.

[0028] Optionally, the selected Ipatov sequence can also be a series of ternary Ipatov sequences {1, 0, 1} of different lengths, and the corresponding reference sequence is consistent with the pulse sequence of the narrow pulse train. In traditional pulse compression waveforms, ternary Ipatov sequences are usually excluded because a complex envelope with a value of "0" means that the pulse is interrupted, which may bring additional problems to the waveform transmission. However, in inter-pulse coding applications, since each coding element is implemented in a separate pulse and there are already many interruptions in the signal, the "0" element of the ternary Ipatov sequence will only mean skipping a pulse. Therefore, if its periodic correlation is ideal, the ternary Ipatov sequence can also be used for coding, and the reference sequence used at this time is consistent with the pulse sequence of the narrow pulse train. Thus, in step S16 above, if the Ipatov sequence uses the ternary Ipatov sequence {1, 0, 1}, when the sequence element is "0", the corresponding pulse will be skipped; during the transmission of the narrow pulse signal, the sequence is cyclically transmitted in time sequence to meet the conditions for cyclic cross-correlation processing.

[0029] As Figure 3 shown, if the cross-correlation is only performed on a single binary Ipatov sequence (Ipatov 13 sequence) and its reference sequence (such as Figure 3 the direct cross-correlation result of the Ipatov 13 sequence shown in (a)), and the result is compared with the autocorrelation result of the Barker 13 sequence of the 13-bit Barker code (such as Figure 3 the direct autocorrelation result of the Barker 13 sequence shown in (b)), it can be found that the sidelobes of the Ipatov 13 sequence are higher, and its autocorrelation sidelobe performance is not as ideal as that of the Barker code.

[0030] To compare the cyclic correlation performance of the Ipatov 13 sequence and the Barker 13 sequence, each of the two sequences is repeated 3 times and then correlated, and the cyclic correlation results of the middle section are observed as shown in Figure 4 the Figure 4 (a) and Figure 4 (b) respectively, Figure 4 (a) is the cyclic cross-correlation result of the Ipatov 13 sequence, Figure 4(b) shows the cyclic correlation results of the Barker 13 sequence. It is noted that at this time, the cyclic correlation results of the Barker 13 sequence still have sidelobes with a value of 1, while the Ipatov 13 sequence achieves zero sidelobes under cyclic autocorrelation. The significance of this feature is that when using inter-pulse phase coding, the positions corresponding to the sidelobes are integer multiples of the PRI, which will cause false target problems in Barker inter-pulse phase coding, while the Ipatov sequence does not have this problem. The selectable Ipatov sequences include binary Ipatov sequences and ternary Ipatov sequences {1, 0, 1}. Among them, the reference sequence corresponding to the binary Ipatov sequence is a specific sequence that does not match it; the reference sequence of the ternary sequence is consistent with the pulse sequence of the narrow pulse train.

[0031] In some embodiments, the Ipatov 13 sequence and the Barker 13 sequence are respectively used to perform inter-pulse phase coding on a pulse sequence with a pulse width T p = 20 ns and a PRI of 2 μs at a sampling rate of 100 MHz. The cyclic correlation results after taking the logarithm are as Figure 5 shown, where Figure 5 (a) shows the coded cyclic correlation results of the full echo signal received when transmitting a narrow pulse signal with inter-pulse phase coding using the Ipatov 13 sequence for cyclic cross-correlation processing, Figure 5 (b) shows the coded cyclic correlation results of the full echo signal received when transmitting a narrow pulse signal with inter-pulse phase coding using the Barker 13 sequence for cyclic cross-correlation processing. It can be seen that due to the still existing fixed sidelobes of the Barker code, uniformly distributed false targets appear in the range dimension (as Figure 5 (b)), while the relatively ideal cyclic correlation performance of the Ipatov sequence avoids the occurrence of this phenomenon (as Figure 5 (a)). At this time, the inter-pulse phase coding waveform encoded with the Ipatov sequence exhibits excellent peak sidelobe ratio (PSLR) performance. The peak sidelobe level PSL of the cross-correlation of the pulse train under 13-bit binary Ipatov sequence coding reaches -321.95 dB, while the peak sidelobe level PSL of the 13-bit Barker sequence is only -22.28 dB. Therefore, the Ipatov sequence can be used as the coding sequence adopted in the inter-pulse phase coding system.

[0032] In the present invention, by increasing the code length of the Ipatov sequence N or increasing the pulse width T p , the peak of the correlation function can be effectively increased, thereby improving the maximum detection range of the radar. Analyzing the pulse width Tp and code length N The influence on the peak value of the cross-correlation function under the inter-pulse phase coding system is used to evaluate the ability of the waveform to support long-range radar detection. As a control, a 13-bit intra-pulse modulation Barker code with an amplitude of 1 and a chip width of 20 ns is used for MATLAB simulation at a sampling rate of 100 MHz, and the autocorrelation peak value is obtained as 26.

[0033] First, analyze the code length N The influence on the peak value of the correlation function. The amplitude of the transmitted signal is set to 1, the sampling rate is the same as above, and the pulse width T p = 20 ns. Respectively use N = 13, 21, 24, 40. Use the average of the absolute values of the reference sequences to normalize it for the purpose of controlling variables. At this time, the corresponding correlation function peak values given by the MATLAB simulation are 26, 42, 48, 80, which is linearly related to the code length N . It can be seen that on the premise that the transmit power and transmit pulse width remain unchanged, the length of the Ipatov sequence used can be increased to increase the number of pulses within a single CPI, thereby increasing the maximum operating range; keep the number of code elements N = 13 unchanged, and analyze the influence of the pulse width on the peak value of the correlation function. At a sampling rate of 100 MHz, according to the Nyquist law, the maximum bandwidth of the complex signal is 100 MHz, corresponding to the shortest pulse width of 10 ns. Keeping other parameters the same, the pulse widths T p = 10, 20, 30, 40, 50 ns are set respectively to observe the change of the correlation function peak value. At this time, the corresponding correlation function peak values given by the simulation are 13, 26, 39, 52, 65, which is also linearly related to the pulse width. Through experimental verification, the peak value of the correlation function is linearly related to the sequence code length N , and similarly, the peak value of the correlation function is also linearly related to the pulse width T p .

[0034] It should be understood that although each step in the above process Figure 1 is shown in sequence according to the arrow indication, these steps are not necessarily executed in the order indicated by the arrow. Unless there is a clear description in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. And the above process Figure 1At least a part of the steps may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed and completed at the same moment, but can be executed at different moments, and the execution order of these sub-steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or sub-steps or stages of other steps.

[0035] All of the above optional technical solutions can be combined arbitrarily to form optional embodiments of the present application, which will not be elaborated one by one here.

[0036] In one embodiment, as Figure 6 shown, there is also provided a long-distance target detection system 100 using narrow pulse signals, including a pulse width determination module 11, a sequence selection module 13, an interval determination module 15, a phase encoding module 17, and a cyclic cross-correlation module 19. Among them, the pulse width determination module 11 is used to determine the currently used pulse width within a set narrow pulse range. The sequence selection module 13 is used to select the Ipatov sequence as the inter-pulse phase encoding sequence and determine the corresponding reference sequence. The interval determination module 15 is used to determine the pulse repetition interval according to the characteristics of the narrow pulse and the maximum detection distance requirement of the radar system. The phase encoding module 17 is used to perform inter-pulse phase encoding on the narrow pulse train of the radar system according to the Ipatov sequence and the pulse repetition interval, generate the transmitted waveform within the coherent processing interval, and transmit it to the target. The cyclic cross-correlation module 19 is used to perform cyclic cross-correlation processing on the complete echo signal corresponding to the transmitted waveform received by the radar system to obtain the distance information of the target.

[0037] For the above long-distance target detection system 100 using narrow pulse signals, by introducing the Ipatov sequence to perform inter-pulse phase encoding on the narrow pulse and adopting full-sampling cyclic cross-correlation processing at the receiving end, the maximum unambiguous distance is extended to N ·PRI, and at the same time, the total energy can be increased by N pulse accumulations. Therefore, it can take into account narrow pulses and long-distance detection, break through the "wide pulse - long distance" binding relationship in traditional radar design, solve the distance ambiguity problem in the high pulse repetition frequency mode, make the maximum unambiguous detection distance determined by PRI change to be determined by CPI, and the maximum unambiguous detection distance can be increased by Ntimes. By performing cyclic cross-correlation processing on the complete echo signal at the receiving end instead of phase discrimination first and then correlation, it is possible to effectively increase the maximum detection range of the radar by increasing the length of the Ipatov sequence or appropriately increasing the pulse width. Moreover, by utilizing the excellent cyclic correlation characteristics of the Ipatov sequence, low sidelobe levels are achieved and the generation of false targets is avoided, improving the accuracy of target detection. Finally, while maintaining the high range resolution of the narrow pulse signal, a large unambiguous maximum detection range is achieved, making the radar system more practical in long-range target detection.

[0038] In one embodiment, the Ipatov sequence is a binary Ipatov sequence, and the reference sequence is a sequence that does not match the binary Ipatov sequence.

[0039] In one embodiment, the Ipatov sequence is a ternary Ipatov sequence, and the reference sequence is consistent with the pulse sequence of the narrow pulse train.

[0040] It can be understood that the explanations of the features in the above-mentioned long-range target detection system 100 using narrow pulse signals can be understood by analogy with the corresponding explanations in the respective embodiments of the above-mentioned long-range target detection method using narrow pulse signals.

[0041] Each module in the above-mentioned long-range target detection system 100 using narrow pulse signals can be implemented in whole or in part by software, hardware, and their combinations. The above-mentioned components can be embedded in or independent of a device with radar data processing functions in hardware form, or stored in the memory of the aforementioned device in software form, so as to facilitate the processor to call and execute the operations corresponding to the above-mentioned modules. The aforementioned device can be, but is not limited to, various existing radar detection computers in the art.

[0042] In one embodiment, a computer device is further provided, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the following processing steps are implemented: determining the currently used pulse width within a set narrow pulse range; selecting an Ipatov sequence as the inter-pulse phase coding sequence and determining the corresponding reference sequence; determining the pulse repetition interval according to the characteristics of the narrow pulse and the maximum detection range requirement of the radar system; performing inter-pulse phase coding on the narrow pulse train of the radar system according to the Ipatov sequence and the pulse repetition interval to generate a transmitted waveform within the coherent processing interval and transmitting it to the target; performing cyclic cross-correlation processing on the complete echo signal corresponding to the transmitted waveform received by the radar system to obtain the distance information of the target.

[0043] In one embodiment, when the processor executes the computer program, it can also implement the additional steps or sub-steps in the respective embodiments of the above-mentioned long-range target detection method using narrow pulse signals.

[0044] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided by the present invention can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), memory bus dynamic random access memory (Rambus DRAM, abbreviated as RDRAM), and interface dynamic random access memory (DRDRAM), etc.

[0045] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0046] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the protection scope of the invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A method for detecting a long-distance target using a narrow pulse signal, characterized in that: Includes steps: Determine the currently used pulse width within the set narrow pulse range; Select the Ipatov sequence as the inter-pulse phase encoding sequence and determine the corresponding reference sequence; The pulse repetition interval is determined according to the characteristics of the narrow pulse and the maximum detection distance requirement of the radar system; According to the Ipatov sequence and the pulse repetition interval, pulse phase encoding is performed on the narrow pulse train of the radar system to generate a transmission waveform within the coherent processing interval and transmit it to the target; The complete echo signal corresponding to the transmitted waveform received by the radar system is subjected to cyclic cross-correlation processing to obtain the distance information of the target.

2. The long-distance target detection method using narrow pulse signals according to claim 1, characterized in that: The Ipatov sequence is a binary Ipatov sequence, and the reference sequence is a sequence that does not match the binary Ipatov sequence.

3. The long-distance target detection method using narrow pulse signals according to claim 1, characterized in that: The Ipatov sequence is a ternary Ipatov sequence, and the reference sequence is consistent with the pulse sequence of the narrow pulse train.

4. A long-distance target detection system using narrow pulse signals, characterized in that: include: A pulse width determination module, used to determine the currently used pulse width within a set narrow pulse range; A sequence selection module, used for selecting an Ipatov sequence as an inter-pulse phase encoding sequence and determining a corresponding reference sequence; An interval determination module, used to determine the pulse repetition interval according to the characteristics of the narrow pulse and the maximum detection distance requirement of the radar system; A phase encoding module, used for performing pulse-to-pulse phase encoding on a narrow pulse train of a radar system according to the Ipatov sequence and the pulse repetition interval, generating a transmission waveform within a coherent processing interval and transmitting the waveform to a target; The cyclic cross-correlation module is used to perform cyclic cross-correlation processing on the complete echo signal corresponding to the transmission waveform received by the radar system to obtain the distance information of the target.

5. The long-distance target detection system using narrow pulse signals according to claim 4, characterized in that: The Ipatov sequence is a binary Ipatov sequence, and the reference sequence is a sequence that does not match the binary Ipatov sequence.

6. The long-distance target detection system using narrow pulse signals according to claim 4, characterized in that: The Ipatov sequence is a ternary Ipatov sequence, and the reference sequence is consistent with the pulse sequence of the narrow pulse train.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the long-distance target detection method using a narrow pulse signal as claimed in any one of claims 1 to 3 are implemented.

Images