A radar communication integrated waveform design method and device

Abstract

The application discloses a radar communication integrated waveform design method and device, and the method comprises the following steps: firstly, generating a DFC sequence and an LFM waveform; then, generating a DFC-LFM waveform according to the DFC sequence and the LFM waveform; then, mapping communication information of a radar communication process to phase shift keying; then, generating a joint coding waveform of the DFC-LFM waveform and the phase shift keying according to the DFC-LFM waveform and the phase shift keying; and finally, generating a RadCom waveform according to the joint coding waveform. The application can provide a low-interception and anti-interference RadCom waveform, improves the anti-interference performance of the radar, and can be widely applied to the technical field of communication.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, and particularly to a radar communication integrated waveform design method and device. BACKGROUND

[0002] With the development of modern science theory, information technology and microelectronic technology, the demand for informationization combat in related fields is urgent, which makes the function of electronic combat and reconnaissance platform evolve from single to multi-functional system. In order to take the initiative in electronic countermeasures, electronic combat platform needs to be equipped with various combat equipment with different functions to improve the comprehensive electronic combat capability, such as radar equipment, communication equipment, jamming equipment, etc. However, the direct superposition of different electronic equipment on the combat platform not only makes it difficult to form a modern platform with high efficient combat capability, but also brings many new problems in energy consumption, concealment, space utilization and electromagnetic compatibility, etc., which leads to the combat platform unable to achieve the ideal combat effectiveness.

[0003] With the rapid development of communication technology, various communication equipment is increasing, leading to increasingly crowded spectrum resource occupation. Meanwhile, whether it is radar or jamming, communication equipment, the basic working mode of which takes electromagnetic wave as the carrier, has high consistency in signal transmission, reception and processing. However, the interaction and sharing performance of these devices for obtaining signals have been ignored, which makes the combat platform unable to form the maximum information sharing advantage. On this basis, the system concept of realizing multiple functions through the same platform is proposed. The platform is no longer a simple superposition of electronic equipment, but different subsystems realize the unification of signal transmission and reception and the sharing of resources. At the same time, the existing radar system occupies a wealth of spectrum resources, but its spectrum resource utilization rate is low in the same time radar working mode. Radar and communication are two indispensable functions of the combat platform. The corresponding equipment has certain similarities in spectrum use, hardware structure and signal transmission and processing. Meanwhile, considering the spectrum efficiency and cost benefit, the combination of the two by using the same set of equipment or sharing part of the device is the preferred form of future wireless equipment. The concept of RadCom system arises at this moment.

[0004] The RadCom system not only has broad application prospects in the military field, but also attracts attention in the civil field. However, it should be noted that radar system and communication system have different performance requirements for waveform performance. When designing integrated waveform, the target detection capability and communication performance of the waveform need to be considered, that is, the RadCom waveform not only needs to complete the radar target detection task, but also needs to have reliable information carrying capability and sufficient information transmission rate. The above analysis shows that the design of integrated waveform directly affects the performance of the whole system, so it is of great practical significance to carry out research on the waveform design of RadCom.

[0005] At present, the method of RadCom waveform design mainly includes three types: the design method based on radar waveform, the design method based on communication waveform and the design method based on space domain. The design method based on radar waveform mainly adopts different modulation modes to load information bits into single or multiple parameters of the existing radar waveform, such as frequency modulation, phase, pulse repetition frequency, pulse frequency hopping rule, etc., or directly uses the radar commonly used waveform as the carrier frequency of the communication signal, and cooperates with the improvement of the receiving algorithm to realize the combination of communication and detection functions. The design method based on communication waveform directly transmits the existing communication waveform or the communication waveform after modification, and the modification method can be spread spectrum, constant envelope control, carrier power distribution, etc. Combined with the improved signal processing algorithm at the receiving end, the waveform has certain target detection capability under the condition of ensuring the communication efficiency. The design method based on space domain can share the advantages of large transmission power and strong beam pointing of the MIMO radar platform with the communication system. By means of multi-domain coding technology such as space-time coding, the joint design of radar communication dual-function waveform is completed, and the effective transmission of communication information in the specified angle direction is realized.

[0006] In a complex environment, in the face of advanced reconnaissance interception and jamming equipment, the RadCom waveform based on radar waveform design is often the first choice because it has excellent target detection capability and certain low interception and anti-jamming performance. However, the RadCom waveform based on LFM improvement has random communication information, and the autocorrelation sidelobe is in a fluctuating state, which affects the target resolution and anti-jamming performance of the waveform. Moreover, although the characteristics of LFM enable the RadCom waveform to have a large time-bandwidth product and a good range-Doppler coupling effect, which can effectively improve the integrated waveform target detection and communication transmission performance, the modulation mode based on LFM is relatively single, and it is difficult to escape from the highly targeted interception analysis of modern reconnaissance equipment in the battlefield. At the same time, potential intermittent forwarding and other interference pose a great threat to the waveform. On the other hand, the LPI radar waveform realized by frequency coding or phase coding can confuse enemy reconnaissance equipment and counter specific jamming, but it does not have the carrying capacity of communication information. SUMMARY

[0007] Therefore, the embodiment of the present application provides a radar communication integrated waveform design method and device to provide a low-interception and anti-jamming RadCom waveform.

[0008] An aspect of the embodiment of the present application provides a radar communication integrated waveform design method, which comprises:

[0009] generating a DFC sequence and an LFM waveform;

[0010] generating a DFC-LFM waveform according to the DFC sequence and the LFM waveform;

[0011] mapping communication information of a radar communication process to a phase shift keying;

[0012] generating a joint encoding waveform of the DFC-LFM waveform and the phase shift keying according to the DFC-LFM waveform and the phase shift keying;

[0013] generating a RadCom waveform according to the joint encoding waveform.

[0014] Optionally, the generating a DFC sequence and an LFM waveform comprises:

[0015] reordering a sequential sequence to obtain the DFC sequence, or generating a pseudo-random sequence as the DFC sequence;

[0016] determining the LFM waveform according to a pulse compression waveform of a radar system.

[0017] Optionally, the method further comprises:

[0018] splitting a radar pulse into a plurality of sub-pulses;

[0019] controlling a carrier frequency of each of the sub-pulses to hop according to the DFC sequence to generate an encoding waveform;

[0020] determining an occurrence time of an autocorrelation peak of the DFC sequence according to the encoding waveform.

[0021] Optionally, the determining the LFM waveform according to a pulse compression waveform of a radar system comprises:

[0022] determining an expression form of a baseband LFM waveform according to a preset waveform pulse width and a waveform bandwidth;

[0023] calculating a differential of a phase of the LFM waveform with respect to time according to the expression form of the baseband LFM waveform to obtain an instantaneous frequency of the LFM waveform;

[0024] determining a linear relationship between the instantaneous frequency of the LFM waveform and time.

[0025] Optionally, the generating a DFC-LFM waveform according to the DFC sequence and the LFM waveform specifically comprises:

[0026] encoding the LFM waveform according to the DFC sequence to obtain the DFC-LFM waveform.

[0027] Optionally, the mapping communication information of a radar communication process to a phase shift keying comprises:

[0028] In the process of communication modulation, three bits of information to be communicated are mapped to a symbol phase, and phase shift keying is constructed by using 8 different phase characteristics to represent digital information.

[0029] Optionally, the generating, according to the DFC-LFM waveform and the phase shift keying, of a joint encoding waveform of the DFC-LFM waveform and the phase shift keying comprises:

[0030] Obtaining the length of the DFC sequence;

[0031] According to the bit phase mapping rule of the phase shift keying, obtaining a phase shift keying sequence;

[0032] According to the DFC-LFM waveform and the phase shift keying sequence, obtaining an expression of a joint encoding waveform.

[0033] Optionally, the generating, according to the joint encoding waveform, of a RadCom waveform comprises:

[0034] Combining the DFC-LFM waveform and the joint encoding waveform in front and back to obtain a RadCom waveform.

[0035] Another aspect of the embodiment of the present application further provides a radar communication integrated waveform design device, comprising:

[0036] A first module is configured to generate a DFC sequence and an LFM waveform;

[0037] A second module is configured to generate a DFC-LFM waveform according to the DFC sequence and the LFM waveform;

[0038] A third module is configured to map communication information of a radar communication process to a phase shift keying;

[0039] A fourth module is configured to generate a joint encoding waveform of the DFC-LFM waveform and the phase shift keying according to the DFC-LFM waveform and the phase shift keying;

[0040] A fifth module is configured to generate a RadCom waveform according to the joint encoding waveform.

[0041] Another aspect of the embodiment of the present application further provides an electronic device, comprising a processor and a memory;

[0042] The memory is configured to store a program;

[0043] The processor executes the program to implement the method as described above.

[0044] The embodiment of the application further discloses a computer program product or a computer program, which comprises computer instructions stored in a computer readable storage medium. A processor of a computer device can read the computer instructions from the computer readable storage medium, and the processor executes the computer instructions, so that the computer device executes the foregoing method.

[0045] The embodiment of the application first generates a DFC sequence and an LFM waveform; then generates a DFC-LFM waveform according to the DFC sequence and the LFM waveform; then maps communication information of a radar communication process to phase shift keying; then generates a joint encoding waveform of the DFC-LFM waveform and the phase shift keying according to the DFC-LFM waveform and the phase shift keying; and finally generates a RadCom waveform according to the joint encoding waveform. The application can provide a low-interception and anti-interference RadCom waveform, and improves the anti-interference performance of the radar. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0047] Figure 1 The overall step flowchart provided by the embodiment of the application is shown in the following figure:

[0048] Figure 2 The schematic diagram of the related characteristics of the DFC sequence is shown in the following figure:

[0049] Figure 3 The DFC sequence encoding waveform schematic diagram is shown in the following figure:

[0050] Figure 4 The LFM waveform schematic diagram is shown in the following figure:

[0051] Figure 5 The ambiguity function schematic diagram of the LFM waveform is shown in the following figure:

[0052] Figure 6 The DFC-LFM waveform schematic diagram is shown in the following figure:

[0053] Figure 7 The 8PSK phase distribution rule schematic diagram is shown in the following figure:

[0054] Figure 8 The joint encoding schematic diagram is shown in the following figure:

[0055] Figure 9 The bit error rate and signal-to-noise ratio relationship curve schematic diagram of the RadCom waveform is shown in the following figure:

[0056] Figure 10 a schematic diagram of a combination of RadCom waveforms;

[0057] Figure 11 a schematic diagram of HRRP results of a single echo pulse after matched filtering;

[0058] Figure 12 a schematic diagram of R-D plot and its velocity dimension slice obtained by HRRP coherent accumulation of multiple RadCom echo pulses;

[0059] Figure 13 a schematic diagram of frequency domain characteristics of RadCom waveforms. DETAILED DESCRIPTION

[0060] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0061] In view of the problems in the prior art, an aspect of an embodiment of the present application provides a radar-communication integrated waveform design method, comprising:

[0062] generating a DFC sequence and an LFM waveform;

[0063] generating a DFC-LFM waveform according to the DFC sequence and the LFM waveform;

[0064] mapping communication information of a radar-communication process to phase shift keying;

[0065] generating a joint encoding waveform of the DFC-LFM waveform and the phase shift keying according to the DFC-LFM waveform and the phase shift keying;

[0066] generating a RadCom waveform according to the joint encoding waveform.

[0067] Optionally, the generating the DFC sequence and the LFM waveform comprises:

[0068] reordering and rearranging a sequential sequence to obtain the DFC sequence, or generating a pseudo-random sequence as the DFC sequence;

[0069] determining the LFM waveform according to a pulse compression waveform of a radar system.

[0070] Optionally, the method further comprises:

[0071] splitting a radar pulse into multiple sub-pulses;

[0072] The carrier frequency of each of the sub-pulses is hopped according to the DFC sequence to generate an encoded waveform;

[0073] An occurrence time of an autocorrelation peak of the DFC sequence is determined according to the encoded waveform.

[0074] Optionally, the LFM waveform is determined according to a pulse compression waveform of a radar system, and the method comprises:

[0075] An expression form of a baseband LFM waveform is determined according to a preset waveform pulse width and a waveform bandwidth;

[0076] A phase-time differential of the LFM waveform is calculated according to the expression form of the baseband LFM waveform to obtain an instantaneous frequency of the LFM waveform.

[0077] A linear relationship between the instantaneous frequency of the LFM waveform and time is determined.

[0078] Optionally, the DFC-LFM waveform is generated according to the DFC sequence and the LFM waveform, and the method comprises:

[0079] The LFM waveform is encoded according to the DFC sequence to obtain the DFC-LFM waveform.

[0080] Optionally, the communication information of the radar communication process is mapped to phase shift keying, and the method comprises:

[0081] In the process of communication modulation, three information bits to be communicated are mapped to a symbol phase to construct phase shift keying that uses eight different phase characteristics to represent digital information.

[0082] Optionally, the joint encoded waveform of the DFC-LFM waveform and the phase shift keying is generated according to the DFC-LFM waveform and the phase shift keying, and the method comprises:

[0083] The length of the DFC sequence is obtained;

[0084] A phase shift keying sequence is obtained according to a bit phase mapping rule of the phase shift keying.

[0085] An expression of the joint encoded waveform is obtained according to the DFC-LFM waveform and the phase shift keying sequence.

[0086] Optionally, the RadCom waveform is generated according to the joint encoded waveform, and the method comprises:

[0087] The DFC-LFM waveform and the joint encoded waveform are combined in front and back to obtain the RadCom waveform.

[0088] Another aspect of the embodiment of the present application further provides a radar communication integrated waveform design device, comprising:

[0089] A first module for generating a DFC sequence and an LFM waveform;

[0090] A second module for generating a DFC-LFM waveform according to the DFC sequence and the LFM waveform;

[0091] A third module for mapping communication information of a radar communication process to phase shift keying;

[0092] A fourth module for generating a joint encoding waveform of the DFC-LFM waveform and the phase shift keying according to the DFC-LFM waveform and the phase shift keying;

[0093] A fifth module for generating a RadCom waveform according to the joint encoding waveform.

[0094] Another aspect of the embodiment of the present application further provides an electronic device comprising a processor and a memory;

[0095] The memory is used for storing a program;

[0096] The processor executes the program to realize the method as described above.

[0097] The embodiment of the present application further discloses a computer program product or a computer program, which comprises computer instructions stored in a computer readable storage medium. A processor of a computer device can read the computer instructions from the computer readable storage medium, and the processor executes the computer instructions to enable the computer device to execute the method as described above.

[0098] The specific implementation process of the present application will be described in detail below in combination with the accompanying drawings of the specification:

[0099] As shown in Figure 1 , the radar communication integrated waveform design method of the present application comprises the following steps:

[0100] Step 1: DFC sequence generation;

[0101] In DFC, the sequence is composed of a group of random and non-repeating integers, and an N-bit DFC sequence can be obtained by randomly rearranging the sequential sequence [0, 1, 2, …, N-1]. In actual engineering, a pseudo-random sequence is generally generated for use as a DFC sequence.

[0102] The uncertainty of the arrangement order of the code word brings the autocorrelation and cross-correlation characteristics as shown in Figure 2 to the DFC sequence.

[0103] in, Figure 2 (a) represents the autocorrelation characteristics of the DFC sequence; Figure 2 (b) represents the cross-correlation characteristics of different DFC sequences.

[0104] By splitting a radar pulse into multiple sub-pulses, and hopping the carrier frequency of each sub-pulse according to a DFC sequence, it is possible to generate... Figure 3 The encoded waveform shown. (By...) Figure 2 (a) It can be seen that the autocorrelation peak of the DFC sequence occurs at the moment when the sequence sliding window is aligned with the sequence, which means that the DFC waveform can concentrate energy to the output main lobe during the matched filtering process, thereby improving the target detection performance. Figure 2 (b) demonstrates the cross-correlation characteristics of DFC sequences, indicating that there is orthogonality between different DFC sequences. When the encoded waveforms are the reference waveform and the received waveform, respectively, the gain cannot be obtained by matched filtering.

[0105] Step 2: LFM waveform generation;

[0106] LFM waveform is a pulse compression waveform widely used in various radar systems today. The linear modulation of the pulse frequency in LFM waveform gives the waveform both a large pulse width and bandwidth, solving the coupling problem of the traditional rectangular pulse transmission pulse width and resolution being mutually exclusive.

[0107] Assuming the pulse width is T and the bandwidth is B, the expression for the baseband LFM waveform is:

[0108]

[0109] Where rect(·) is a rectangular function, k is the frequency modulation slope, and satisfies A schematic diagram of the waveform is shown below. Figure 4 As shown, where, Figure 4 (a) shows the time-domain plot of the LFM waveform; Figure 4 (b) shows the time-frequency relationship of the LFM waveform.

[0110] The instantaneous frequency of an LFM waveform is the differential of its phase with respect to time, i.e.

[0111]

[0112] As can be seen from equation (2), the instantaneous frequency of the waveform satisfies a linear relationship with time. Assuming K > 0, within the time interval... Within, the instantaneous frequency of the waveform will be from linearly increasing to like Figure 4 As shown in (b).

[0113] The Ambiguity Function of LFM waveform is like a slanted knife edge, as shown in Figure 5 . This shape represents the range-Doppler coupling property of LFM waveform, which shows that LFM waveform has the following advantages:

[0114] (1) It effectively solves the problem that rectangular pulse does not have Doppler tolerance ability;

[0115] (2) When the range (velocity) of the detected target is known, very high range (velocity) accuracy can be obtained;

[0116] (3) In the scenario of detecting multiple targets with the same speed (range), the target resolution ability in the range (velocity) dimension is very high.

[0117] Step 3: DFC-LFM waveform generation;

[0118] Combining DFC and LFM waveform together, the resulting waveform can further improve the time-bandwidth product to improve the target resolution ability, and can also take advantage of the sequence correlation characteristics and range-Doppler coupling characteristics.

[0119] The single pulse expression of DFC-LFM waveform coded by N-bit DFC is:

[0120]

[0121]

[0122] Wherein, the whole pulse contains N sub-pulses, and the sub-pulse u(t) is a rectangular pulse with pulse width T p , whose expression is shown in equation (4), T r is the repetition interval of the sub-pulse, and K is the frequency modulation slope of the waveform. The carrier frequency f n of the nth sub-pulse is:

[0123] f n = f c + c n Δf,n = 0,1,…,N-1 (5)

[0124] Wherein, f c is the reference carrier frequency, c n is the nth code word of the DFC sequence, and Δf is the frequency hopping step of the carrier frequency, satisfying Δf = 1 / T p .

[0125] After DFC coding, the time-frequency distribution can be obtained as Figure 6The DFC-LFM waveform of the figure. The enemy reconnaissance aircraft needs to detect and identify the waveform after interception in the absence of prior information, and the time-frequency relationship of the waveform in the figure is quite complex, which can greatly improve the processing difficulty of the reconnaissance aircraft, which reflects the good low interception performance of the waveform.

[0126] Step 4: Map the communication information to 8PSK;

[0127] Phase shift keying (PSK) is a high transmission efficiency modulation method, which has stronger anti-noise ability than amplitude shift keying (ASK) and frequency shift keying (FSK), and is not easily affected by channel characteristics, so it is widely used in high-speed and medium-speed transmission in the communication field. 8PSK is a kind of multi-phase keying modulation technology with high frequency band utilization, which uses 8 different phase characteristics of the carrier to represent digital information. In each modulation, 8PSK maps 3 bits of information to be transmitted into a symbol phase, so the symbol rate is 1 / 3 of the bit rate. The phase distribution rule of 8PSK can be represented by 8 points distributed equidistantly on a unit circle, as shown in the figure. Figure 7

[0128] As can be seen from Figure 7 , 8PSK selects 8 phase points equidistantly in a phase period 0~2π, and the phase difference between every two adjacent phase points is 2π / 8=π / 4. Assuming that the radius is A and the initial phase is 0, 3 bits of information to be transmitted are mapped to the i-th phase , an 8PSK symbol can be represented as:

[0129]

[0130] Step 5: Joint encoding waveform generation of DFC-LFM and 8PSK;

[0131] The joint encoding waveform is obtained by combining two or more modulation methods for radar transmitting waveform. The joint encoding waveform can make up for the shortcomings of a single modulation waveform, so that the transmitting waveform has a large time-bandwidth product, and the range and velocity resolution of the radar is improved. At the same time, the complex modulation method makes it difficult to detect and identify the signal, greatly reducing the probability of interception.

[0132] In the waveform design method proposed in the present application, the phase encoding sequence length of the waveform is equal to the length of the DFC sequence. Assuming that the length of the DFC sequence is N, according to the bit-to-phase mapping rule of 8PSK, the number of communication bits is 3N. The 8PSK sequence obtained by mapping the communication bits generated according to the random communication content can be represented as:

[0133] Combined with the expression of the DFC-LFM waveform and the 8PSK sequence, the expression of the joint encoding waveform can be obtained:​

[0134]

[0135] Figure 8 For the joint encoding diagram of the waveform, the joint encoding of the DFC-LFM waveform by 8PSK has two aspects of effects. On the one hand, the communication information is embedded in the waveform, so that the joint encoding waveform meets the dual-function requirement of RadCom. On the other hand, the modulation complexity of the waveform is increased on the basis of DFC, and the target detection and anti-interception, anti-interference performance of the waveform are further improved.

[0136] The joint encoding waveform is the front section of the RadCom waveform, and plays a role in carrying communication information and acting as a radio frequency cover. In the modern battlefield environment, the communication information carried by the RadCom waveform is only transmitted between the devices of the same side. The devices of the same side have prior information related to the integrated waveform, and can complete the trigger reception of the front section of the RadCom waveform by controlling the receiver.

[0137] According to the design idea of the present application, the RadCom waveform can achieve the following communication performance:

[0138] The effectiveness of communication, that is, the information transmission rate. The present application uses 8PSK to load information onto the waveform, and each sub-pulse of the joint encoding part of the waveform carries 3 bits. If the pulse width of the radar transmitted pulse is about 50 microseconds, and the width of the sub-pulse is selected to be 1us, then the RadCom waveform as a transmitted pulse can transmit about 48-96 bits. Such an information rate is not outstanding in the traditional communication field, but in the modern battlefield environment where the new system radar is located, it has met the transmission requirements of battlefield information.

[0139] The reliability of communication, the bit error rate curve of the RadCom waveform under the Gaussian white noise channel is as shown in Figure 9 When the signal-to-noise ratio is greater than or equal to 0dB, the bit error rate of the designed waveform is basically 0. This shows that the communication information demodulated and recovered from the waveform is very reliable, unless the channel environment is further deteriorated.

[0140] Step 6: Radar-communication integrated waveform combination generation.

[0141] The waveform designed in the present application can be regarded as being composed of two waveforms due to the difference in intrapulse modulation mode. By using this characteristic, the combination of the encoding waveforms modulated in steps 4 and 5 can generate the RadCom waveform of the present application. The combination mode of the RadCom waveform is as shown in Figure 10 Combining formulas (3) and (7), the expression of the Figure 10 waveform in the middle can be obtained:

[0142]

[0143] By Figure 10 It can be seen that the combined waveform has two parts according to the different intra-pulse modulation modes. The front part of the waveform using 8PSK is the joint coding waveform of step 5, which plays a role in carrying communication information and serving as a radio frequency cover. The rear part of the waveform is the DFC-LFM waveform of step 4, which will be used as a reference signal in the matching filtering process at the receiving end. The combined waveform as a whole will be used for radar detection of the target by the transmitted pulse. In the construction process of the RadCom waveform, the use of two groups of DFC sequences with the same length but different code words is the key.

[0144] According to the design idea of the present application, the expected performance of the RadCom waveform in target detection and resolution, anti-interception and anti-jamming is as follows:

[0145] Suppose that the echo of the RadCom waveform contains two point targets with a distance of 15m and a speed difference of 0.15m / s, and under the condition of low signal-to-noise ratio, the HRRP result of a single echo pulse after matching filtering is as shown in Figure 11 .

[0146] By Figure 11 It can be seen that the RadCom waveform can distinguish two targets with close distances and has high range resolution. By comparing the upper and lower results in the figure, it can be found that under the condition of low signal-to-noise ratio, the HRRP taking the whole transmitted waveform as a reference appears multiple false targets, which will make it very difficult to set the detection threshold and easily cause obvious false alarm detection; while the HRRP taking the rear part of the waveform as a reference has much lower requirement for the setting of the detection threshold under the same signal-to-noise ratio condition, and has excellent target detection performance.

[0147] Figure 12 is a schematic diagram of the R-D diagram and the velocity (Doppler) dimension slice obtained by coherent accumulation of the HRRP of multiple echo pulses.

[0148] From the slice result, it can be seen that the RadCom waveform can obviously distinguish two targets with close distances and similar speeds, which shows that the waveform has excellent resolution ability in both the range dimension and the velocity dimension.

[0149] The frequency domain characteristics of the RadCom waveform are as shown in Figure 13 , wherein Figure 13 (a) is the frequency spectrum of the waveform, Figure 13 (b) is the time-frequency diagram of the waveform.

[0150] By Figure 13It can be seen that the RadCom waveform has a large bandwidth, and its frequency spectrum is as messy as noise spectrum. In terms of time-frequency distribution, the time-frequency diagram of the RadCom waveform presents a random jump feature, and there is no rule. Such frequency domain characteristics increase the difficulty of interception and subsequent decryption of the waveform by enemy reconnaissance receivers, and improve the anti-interception performance of the waveform.

[0151] In terms of anti-interference, the jammer usually performs copy processing based on the front of the waveform signal. After obtaining the local signal (i.e. slice) by sampling copy, the most direct interference mode is to delay and forward it, that is, to superimpose the slice forwarding interference on the echo, thereby disturbing the target detection process at the radar receiving end.

[0152] According to the cross-correlation characteristics of the DFC sequence in step 1, there is orthogonality between the DFC waveforms obtained by different sequence encoding. Since the RadCom waveform designed in the application is encoded by two different DFC sequences, and the local waveform is used as the reference signal for matched filtering. Such design makes it impossible for the slice forwarding interference to obtain sufficient gain at the receiving end under the radio frequency cover of the front section of the waveform, which can effectively avoid the influence of interference on target detection.

[0153] In summary, the application has the following characteristics:

[0154] 1. A low-interception and anti-interference RadCom waveform is designed, and the interference type to be countered is slice forwarding interference;

[0155] 2. A joint encoding waveform design method of DFC and PSK is proposed, and the designed waveform can realize the combination of radar detection and communication information transmission functions, and has good low-interception characteristics;

[0156] 3. A construction method of multifunctional integrated combined waveform is invented. By controlling the intrapulse modulation mode (frequency modulation, phase modulation, etc.) and combination order of the segmented waveform, and cooperating with the selection of the reference waveform of the receiving end matched filtering, the target detection, target resolution and anti-interference ability of the waveform are effectively improved;

[0157] 4. The designed waveform belongs to a highly covert RadCom waveform, and the enemy reconnaissance receiver cannot know that the waveform carries communication information through the commonly used frequency domain or time-frequency analysis method;

[0158] 5. A radio frequency cover waveform is designed to improve the radar anti-interference performance.

[0159] In the existing waveform design technology, the designed RadCom waveform generally does not have the characteristics of anti-interception and anti-interference. The information carrying capacity of the LPI radar waveform with good anti-interference performance has not been studied. The application proposes a new multifunctional waveform design method, and designs a low-interception and anti-interference RadCom waveform.

[0160] In some alternative embodiments, the functions / operations mentioned in the block diagrams can not occur in the order mentioned in the operation diagram. For example, depending on the functions / operations involved, two blocks shown in succession can actually be executed substantially concurrently or the blocks can sometimes be executed in reverse order. Furthermore, the embodiments presented and described in the flow diagrams of the application are provided by way of example only. The disclosed methods are not limited by the illustrated and described operations and logic flows. Alternative embodiments are contemplated in which the order of various operations is changed and in which sub-operations described as part of a larger operation are executed independently.

[0161] Furthermore, although the application is described in the context of functional modules, it should be understood that one or more of the described functions and / or features can be integrated in a single physical device and / or software module, or one or more functions and / or features can be implemented in separate physical devices or software modules, unless otherwise specified. It can also be understood that a detailed discussion of the actual implementation of each module is unnecessary for an understanding of the application. Rather, consideration of the properties, functions and internal relationships of the various functional modules disclosed in the devices herein, within the context of the attributes, functions and internal relationships of the modules, will be within the ordinary skill of the engineer. Therefore, those skilled in the art with ordinary skill can implement the application as set forth in the claims without undue experimentation, using ordinary skill. It can also be understood that the disclosed specific concepts are merely illustrative and are not intended to limit the scope of the application, which is determined by the full scope of the appended claims and their equivalents.

[0162] If the functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the parts of the technical solutions that essentially contribute to the prior art or the parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0163] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered a list of executable instructions for implementing logic functions, and can be specifically embodied in any computer-readable medium for use by an instruction execution system, apparatus, or device, such as a computer-based system, a system including a processor, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions, or in conjunction with these instructions execution systems, apparatuses, or devices. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport programs for use by an instruction execution system, apparatus, or device, or in conjunction with these instruction execution systems, apparatuses, or devices.

[0164] More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection having one or more wires (electrical devices), a portable computer diskette (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium can even be paper or other suitable medium on which the program can be printed, as the program can be electronically obtained, for example, by optical scanning of the paper or other medium, followed by editing, interpreting, or otherwise processing, if necessary, in other suitable ways to be electronically obtained, and then stored in the computer memory.

[0165] It should be understood that aspects of the application can be implemented in hardware, software, firmware or a combination thereof. In the above embodiments, various steps or methods can be implemented in software or firmware which is stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, and in another embodiment, any of the following technologies, known in the art, can be used: a combination of discrete logic circuits having logic gates for implementing logic functions upon an application of data signals, application specific integrated circuits having logic gates, field programmable gate arrays (FPGA), or other components, in combination or as the case can be.

[0166] In the description of the present application, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. The illustrative appearances of the above terms in various places in the specification are not intended to exclude that the terms in other places mean the same or similar features, structures, materials, or characteristics. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0167] Although embodiments of the present application have been shown and described, it would be appreciated by those skilled in the art that changes can be made in these embodiments without departing from the principles and spirit of the application, the scope of which is defined in the claims and their equivalents.

[0168] The above is a specific description of the preferred embodiments of the present application, but the present application is not limited to the described embodiments, and those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the present application, and these equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. A waveform design method for integrated radar communication, characterized in that, include: Generate DFC sequences and LFM waveforms; Based on the DFC sequence and the LFM waveform, a DFC-LFM waveform is generated; Mapping the communication information of the radar communication process to phase shift keying; Based on the DFC-LFM waveform and the phase shift keying, a joint encoded waveform of the DFC-LFM waveform and the phase shift keying is generated; Based on the jointly encoded waveform, a RadCom waveform is generated; The generation of the DFC sequence and LFM waveform includes: The DFC sequence is obtained by rearranging the sequential sequence into random order, or by generating a pseudo-random sequence as the DFC sequence. The LFM waveform is determined based on the pulse compression waveform of the radar system; The process of mapping communication information from the radar communication process to phase shift keying includes: In the process of communication modulation, three information bits to be transmitted are mapped to a symbol phase, and phase shift keying is constructed using eight different phase features to characterize digital information. The step of generating a jointly encoded waveform of the DFC-LFM waveform and the phase shift keying based on the DFC-LFM waveform and the phase shift keying includes: Get the length of the DFC sequence; Based on the bit phase mapping rules of phase shift keying, the phase shift keying sequence is obtained; Based on the DFC-LFM waveform and the phase shift keying sequence, the expression for the jointly encoded waveform is obtained; The step of generating the RadCom waveform based on the jointly encoded waveform includes: The DFC-LFM waveform is combined with the joint encoded waveform to obtain the RadCom waveform.

2. The integrated radar-communication waveform design method according to claim 1, characterized in that, The method further includes: The radar pulse is split into multiple sub-pulses; The carrier frequency of each sub-pulse is controlled to jump according to the DFC sequence to generate an coded waveform; The occurrence time of the autocorrelation peak of the DFC sequence is determined based on the encoded waveform.

3. The integrated radar-communication waveform design method according to claim 1, characterized in that, Determining the LFM waveform based on the pulse compression waveform of the radar system includes: The expression form of the baseband LFM waveform is determined based on the preset waveform pulse width and waveform bandwidth. The instantaneous frequency of the LFM waveform is obtained by calculating the phase derivative with respect to time of the LFM waveform based on the expression of the baseband LFM waveform. Determine the linear relationship between the instantaneous frequency and time of the LFM waveform.

4. The integrated radar-communication waveform design method according to claim 1, characterized in that, The step of generating the DFC-LFM waveform based on the DFC sequence and the LFM waveform specifically involves: The LFM waveform is encoded according to the DFC sequence to obtain the DFC-LFM waveform.

5. A radar communication integrated waveform design device, characterized in that, include: The first module is used to generate DFC sequences and LFM waveforms; The second module is used to generate a DFC-LFM waveform based on the DFC sequence and the LFM waveform; The third module is used to map the communication information of the radar communication process to phase shift keying; The fourth module is used to generate a joint encoded waveform of the DFC-LFM waveform and the phase shift keying based on the DFC-LFM waveform and the phase shift keying. The fifth module is used to generate a RadCom waveform based on the jointly encoded waveform; The generation of the DFC sequence and LFM waveform includes: The DFC sequence is obtained by rearranging the sequential sequence into random order, or by generating a pseudo-random sequence as the DFC sequence. The LFM waveform is determined based on the pulse compression waveform of the radar system; The process of mapping communication information from the radar communication process to phase shift keying includes: In the process of communication modulation, three information bits to be transmitted are mapped to a symbol phase, and phase shift keying is constructed using eight different phase features to characterize digital information. The step of generating a jointly encoded waveform of the DFC-LFM waveform and the phase shift keying based on the DFC-LFM waveform and the phase shift keying includes: Get the length of the DFC sequence; Based on the bit phase mapping rules of phase shift keying, the phase shift keying sequence is obtained; Based on the DFC-LFM waveform and the phase shift keying sequence, the expression for the jointly encoded waveform is obtained; The step of generating the RadCom waveform based on the jointly encoded waveform includes: The DFC-LFM waveform is combined with the joint encoded waveform to obtain the RadCom waveform.

6. An electronic device, characterized in that, Including the processor and memory; The memory is used to store programs; The processor executes the program to implement the method as described in any one of claims 1 to 4.

Images