Anti-Jamming Integrated Radar and Communication Signal Design Method

Abstract

The present invention relates to a radar-communication integrated signal design method with broadband anti-interference ability, belonging to the field of radar-communication integration. In the present invention, user data is grouped into a p-bit selection mapping group and a q-bit phase shift mapping group. According to a one-to-one mapping relationship, each data combination of the p-bit selection mapping group is respectively mapped to select the i-th orthogonal sequence from N orthogonal sequences to participate in modulation, and each data combination of the q-bit phase shift mapping group is respectively mapped to the cyclic shift state of the i-th orthogonal sequence. Pulse amplitude modulation is adopted to sequentially load each bit of data in the cyclic shift state of the i-th orthogonal sequence onto the prolate spheroidal wave function, and its integral form is used as the additional phase of the exponential-type non-linear frequency modulation signal to form a radar-communication integrated modulation signal. The technical solution disclosed by the present invention improves the anti-interference ability, information transmission ability and power utilization rate of the radar-communication integrated modulation signal.

Description

Technical Field

[0001] The present invention relates to a radar-communication integrated signal design method with broadband anti-interference ability, belonging to the field of radar-communication integration. Background Art

[0002] Radar-communication integration mainly realizes information transmission by sharing radar resources for communication. While detecting and positioning targets, the integrated shared signal can also transmit information to complete the communication function. The integrated shared signal is both a communication signal and a radar signal. Based on the integration of signal sharing, the research focus lies in the design method of the integrated shared signal and the modulation and demodulation technology of the signal. With the rapid development of modern electronic technology, electronic warfare has become a new battlefield in modern warfare.

[0003] Designing radar-communication integrated waveforms based on OFDM is a research hotspot in the existing field of radar-communication integration. This technology uses the high information transmission rate of OFDM-modulated signals to improve the transmission rate of the system. At the same time, when OFDM-modulated signals are used in radar systems, due to their characteristics of large time-bandwidth product signals, they can also meet the requirements of high range resolution and high velocity resolution for radar target detection. However, the inherent high peak-to-average power ratio (PAPR) characteristic of OFDM significantly reduces the power utilization efficiency of the system, thereby reducing the detection range of the radar system for targets and seriously affecting the working performance of the radar system.

[0004] In the field of radar-communication integration, while improving the effectiveness of the radar-communication integrated system, it is also very important to improve the anti-electronic interference ability of the system, which is related to important indicators such as the flexibility and reliability of detecting targets. High-tech electronic equipment such as radar, communication, and electronic countermeasures undertakes tasks such as information acquisition, network transmission, and electromagnetic usage rights competition, and is the core element of the electronic countermeasure system under information-based conditions. Since the 1990s, with the development of radar electronic countermeasure technology, especially the rapid development of active interference technology based on digital radio frequency memory, whether radar-communication integrated signals can have adaptability in complex electromagnetic environments has posed a severe challenge to the design of radar-communication integrated signals.

[0005] Therefore, how to improve the information transmission efficiency and power efficiency of the system while enhancing the anti-interference ability of radar-communication integrated signals is a difficult problem that needs to be solved in the existing design of radar-communication integrated signals. Summary of the Invention

[0006] The purpose of the present invention is to solve the deficiencies existing in the above-mentioned prior art, and provide a radar-communication integrated design method that can improve the information transmission efficiency and power efficiency of the system while enhancing the anti-interference ability of radar-communication integrated signals.

[0007] To achieve the object of the present invention, the present invention provides an anti-interference radar communication integrated signal design method, which is characterized in that in this method, the radar communication integrated signal is:

[0008]

[0009] where f c is the carrier frequency of the radar communication integrated modulation signal, is the exponential non-linear frequency modulation factor, B is the signal bandwidth factor, is the j-th bit data of the k-th cyclic shift state of the i-th orthogonal sequence participating in modulation, j is a positive integer, j = 1, 2, … M, where M is the total number of bits of the i-th orthogonal sequence, k is a positive integer, k = 0, 1, 2, … M - 1, θ(j) is the initial phase factor, γ n (c, t) is the prolate spheroidal wave function, n is the order of the prolate spheroidal wave function, and c is the time-bandwidth product factor.

[0010] Furthermore, the radar communication integrated signal includes the following design steps:

[0011] Step 1: Group the data D(t) to be transmitted by the user. The grouping includes a p-bit selection mapping group Y(t) = {y1(t), y2(t), …, y p (t)} and a q-bit phase shift mapping group A(t) = {a1(t), a2(t), …, a q (t)};

[0012] Step 2: According to the one-to-one mapping relationship, map each data combination of the p-bit selection mapping group to select the i-th orthogonal sequence from N orthogonal sequences to participate in modulation. Each data combination of the p-bit selection mapping group can only be mapped to one orthogonal sequence, and the orthogonal sequences mapped by any two data combinations are different;

[0013] Step 3: According to the one-to-one mapping relationship, map each data combination of the q-bit phase shift mapping group to the cyclic shift state of the i-th orthogonal sequence. Each data combination of the q-bit phase shift mapping group can only be mapped to one cyclic shift state of the i-th orthogonal sequence, and the cyclic shift states of the orthogonal sequences mapped by any two data combinations are different;

[0014] Step 4: Adopt pulse amplitude modulation to sequentially load each bit data of the cyclic shift state of the i-th orthogonal sequence onto the prolate spheroidal wave function γ n (c, t), and use its integral form as the additional phase of the exponential non-linear frequency modulation signal to form a radar communication integrated modulation signal.

[0015] Further, the initial phase factor θ(j) is: where j is a positive integer, j = 1, 2, … N.

[0016] Further, the N orthogonal sequences are pairwise orthogonal or quasi-orthogonal, and all have M bits.

[0017] Further, p and N satisfy the relation: The symbol denotes rounding down.

[0018] Further, q and M satisfy the relation: The symbol denotes rounding down.

[0019] Preferably, the γ n (c, t) is the zero-order prolate spheroidal wave function, and the time-bandwidth product factor is c = 4π.

[0020] Preferably, the cyclic shift is a cyclic left shift or a cyclic right shift, and each time 1 bit of data is cycled.

[0021] Preferably, the N orthogonal sequences are bipolar orthogonal sequences.

[0022] Preferably, the data D(t) to be transmitted by the user is grouped by 5 bits, and the grouping includes a 2-bit selection mapping group and a 3-bit phase shift mapping group.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The power utilization rate of the system is improved.

[0025] In the technical solution disclosed by the present invention, for the pulse waveform that completes data loading, an integral form is used as the additional phase of the exponential nonlinear frequency modulation signal to realize the integrated radar communication waveform design, so that the integrated modulation signal has a constant envelope characteristic. Therefore, compared with the prior art, the power utilization rate of the radar system can be effectively improved, and the detection range of the target can be enhanced.

[0026] (2) The anti-interference ability of the system is improved.

[0027] In the technical solution disclosed by the present invention, by adopting the methods of orthogonal sequence selective mapping and orthogonal sequence phase shift mapping, the information to be transmitted is loaded onto orthogonal sequences, realizing spectrum spreading, reducing the power spectral density of the radar-communication integrated modulation signal, and improving the concealment performance. Further, by combining orthogonal sequence selection with the initial phase factor, the radar-communication integrated signal is prevented from coherently accumulating in the time domain and frequency domain with the repeater interference signal. Further, since the orthogonal sequences mapped by different data packets are different, the receiving system can utilize their orthogonality or quasi-orthogonality to convert the interference signals carrying different orthogonal sequences into low-power spectral noise signals, effectively suppressing the repeater interference, thereby improving the anti-interference ability.

[0028] (3) The information transmission efficiency of the system is improved.

[0029] In the technical solution disclosed by the present invention, the traditional method of only loading information using amplitude parameters is abandoned, the ways of loading information in the transmission waveform are expanded, and three methods, namely orthogonal sequence selective mapping, orthogonal sequence phase shift mapping, and pulse amplitude modulation, are used to load information simultaneously, effectively improving the information transmission efficiency of the system.

[0030] (4) The signal-to-interference ratio of the radar-communication integrated signal is improved.

[0031] In the prior art, linear frequency modulation signals are often used to design radar-communication integrated signals. Such signals have large sidelobes. When suppressing the sidelobes through filters, it will cause serious waveform distortion of the radar modulation signal, thereby reducing the anti-interference ability of the radar signal during channel transmission. In the technical solution disclosed by the present invention, an exponential type is adopted to construct the non-linear frequency domain characteristics to achieve the purpose of reducing the sidelobe amplitude of the radar modulation signal, reducing the signal distortion generated when suppressing the sidelobes, improving the signal-to-interference ratio of the radar signal, making it have strong anti-electromagnetic interference ability during channel transmission, and thus improving the reliability of the transmission of the radar-communication integrated modulation signal. Description of the Drawings

[0032] Figure 1 is a schematic diagram of the generation of the radar-communication integrated modulation signal disclosed in the embodiment of the present invention. Detailed Embodiment

[0033] The following further elaborates on the present invention in detail in conjunction with the embodiments and the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0034] In the prior art, when OFDM technology is used for the integrated design of radar and communication signals, due to its inherent high peak-to-average power ratio (PAPR) characteristic, the power utilization efficiency of the system is significantly reduced, thereby reducing the detection range of the radar system for targets and seriously affecting the working performance of the radar system. Although the method of reducing the PAPR can alleviate the PAPR of the modulated signal to a certain extent, the PAPR of the modulated signal still fluctuates within a large range, so the problem cannot be fundamentally solved. The high PAPR characteristic reduces the power utilization efficiency of the integrated radar and communication system, resulting in limited signal power transmitted by the transmitter and reducing the anti-interference ability.

[0035] In the prior art, compared with OFDM technology, the linear frequency modulation (LFM) signal has a constant envelope characteristic, which guarantees the power efficiency of the system, and has a relatively wide spectral bandwidth, which can improve the resolution when detecting targets. However, the LFM signal has large spectral side lobes. When suppressing the side lobes through filtering, it will cause serious waveform distortion of the modulated signal, resulting in a decrease in the signal-to-noise ratio (SNR) of the signal and reducing the anti-interference ability of the signal during channel transmission, so its application environment is relatively limited.

[0036] With the development of radar electronic countermeasure technology, especially the rapid development of active interference technology based on digital radio frequency memory, it has brought severe challenges to the adaptability of integrated radar and communication signals in complex electromagnetic environments. It is necessary to improve the anti-interference ability of integrated radar and communication signals.

[0037] To solve this problem and improve the anti-interference ability of integrated radar and communication signals, the present invention discloses a design method for anti-interference integrated radar and communication signals. In the technical solution disclosed in the embodiments of the present invention, an exponential-type non-linear frequency domain characteristic is adopted for the modulated signal to construct a non-linear frequency modulation radar modulated signal, that is

[0038]

[0039] where f c is the carrier frequency of the integrated radar and communication modulated signal, is the exponential-type non-linear frequency modulation factor, B is the signal bandwidth factor, and j is a positive integer representing the number of data bits. The exponential-type frequency domain characteristic makes the radar modulated signal exhibit non-linear characteristics, so as to achieve the purpose of reducing the side lobe amplitude of the radar modulated signal, reducing the signal distortion generated when the radar signal passes through antenna filtering and radiation, thereby improving the SNR (signal-to-noise ratio) of the radar modulated signal, making it have strong anti-electromagnetic interference ability during channel transmission, and thus expanding its applicable application environment.

[0040] Therefore, the embodiments of the present invention use non-linear frequency modulation signals to design radar signals, which can improve the reliability of their transmission. On this basis, an integrated design with communication modulation signals is carried out to achieve better radar detection performance and data transmission performance.

[0041] In the field of radar electronic countermeasures, deceptive jamming and repeater jamming are one of the common types of jamming. Deceptive jamming intercepts the signal to be jammed through a listening device, analyzes its signal characteristics, obtains signal parameters, and on this basis, the jammer releases a deceptive jamming signal with similar parameters to implement jamming. Therefore, the prerequisite for the effective implementation of this type of jamming is to obtain radar signal parameters. Compared with deceptive jamming, repeater jamming does not require obtaining radar signal parameters. By amplifying the received signal to be jammed and then forwarding it to the system to be jammed, the purpose of implementing jamming is achieved.

[0042] To effectively counter deceptive jamming and repeater jamming, the embodiments of the present invention disclose an anti-jamming radar communication integrated signal design method. In this method, the radar communication integrated modulation signal is:

[0043]

[0044] where f c is the carrier frequency of the radar communication integrated modulation signal, is an exponential non-linear frequency modulation factor, B is a signal bandwidth factor, is the j-th bit of the k-th cyclic shift state of the i-th orthogonal sequence participating in modulation, j is a positive integer, j = 1, 2,... M, where M is the total number of bits of the orthogonal sequence, k is a positive integer, k = 0, 1, 2,... M - 1, θ(j) is an initial phase factor, γ n (c, t) is a prolate spheroidal wave function, n is the order of the prolate spheroidal wave function, and c is a time-bandwidth product factor.

[0045] Furthermore, as Figure 1 shown, in the technical solution disclosed in the embodiments of the present invention, generating the radar communication integrated modulation signal includes the following steps:

[0046] Step 1: Group the data D(t) to be transmitted by the user. The grouping includes a p-bit selection mapping group Y(t) = {y1(t), y2(t),..., y p (t)} and a q-bit phase shift mapping group A(t) = {a1(t), a2(t),..., a q (t)};

[0047] Step 2: According to the one-to-one mapping relationship, each data combination of the p-bit selection mapping group is respectively mapped to select the i-th orthogonal sequence from N orthogonal sequences to participate in modulation. Each data combination of the p-bit selection mapping group can only be mapped to one orthogonal sequence, and the orthogonal sequences mapped by any two data combinations are different from each other;

[0048] Step 3: According to the one-to-one mapping relationship, each data combination of the q-bit phase shift mapping group is respectively mapped to the cyclic shift state of the i-th orthogonal sequence. Each data combination of the q-bit phase shift mapping group can only be mapped to one cyclic shift state of the i-th orthogonal sequence, and the cyclic shift states mapped by any two data combinations are different from each other;

[0049] Step 4: Using pulse amplitude modulation, each bit of data of the cyclic shift state of the i-th orthogonal sequence is sequentially loaded onto the prolate spheroidal wave function γ n (c,t), and its integral form is used as the additional phase of the exponential frequency modulation signal to form a radar-communication integrated modulation signal.

[0050] In the technical solution disclosed in the embodiments of the present invention, the data D(t) to be transmitted by the user is grouped, and the data to be transmitted is mapped to the orthogonal sequence c i (t) through the methods of selection mapping and phase shift mapping. The number of bits M of the orthogonal sequence c i (t) is greater than the number of bits of the data grouping, that is, the chip duration in the orthogonal sequence c i (t) is less than the data duration in the data grouping. According to the transformation relationship between duration and spectrum, after mapping, spectrum broadening is achieved, and the effect of spreading spectrum is achieved, thereby reducing the power spectral density of the signal, improving the concealment ability of the signal, making it difficult for reconnaissance equipment to obtain the waveform parameters of the radar-communication integrated signal, and thus making it difficult to effectively implement spoofing interference.

[0051] Further, in the technical solution disclosed in the embodiments of the present invention, each data combination of the p-bit selection mapping group is respectively mapped to select the i-th orthogonal sequence from N orthogonal sequences to participate in modulation, that is, the orthogonal sequences mapped by different data combinations of the selection mapping group are different from each other, so that the orthogonal sequences adopted between different data packets are different from each other and are orthogonal or quasi-orthogonal to each other; it makes it difficult for the repeater interference to effectively interfere with the signals across data packets. Because the orthogonal sequences adopted by different data packets are different from each other and satisfy the pairwise orthogonal or quasi-orthogonal relationship, the radar-communication integrated receiving system can utilize the orthogonal or quasi-orthogonal relationship between different sequences to match and receive useful signals according to their correlation. For the repeater interference signal, the receiving system can utilize its orthogonality or quasi-orthogonality to convert the interference signals carrying different orthogonal sequences into low-power spectral noise signals. Therefore, the repeater interference can be effectively suppressed. To implement effective repeater interference, the entire process of repeater interference must be completed within the time of one data packet, and the time of one data packet is extremely short, which forces the repeater interference platform to be very close to the interfered platform, which is difficult to achieve in the actual battlefield environment.

[0052] Further, in the technical solution disclosed in the embodiments of the present invention, in order to further prevent the radar-communication integrated signal from coherently accumulating with the repeater interference signal in the time domain and frequency domain, the integrated signal is also provided with an initial phase factor θ(j), and the initial phase factor θ(j) is: where j is a positive integer, j = 1, 2, … M, that is, the initial phase size is closely related to the number of bits of the orthogonal sequence, and the initial phases between each bit are different from each other, thereby further increasing the coherent difference between the integrated signal and the repeater interference. By combining the orthogonal sequence and the initial phase factor, the coherent accumulation of the radar-communication integrated signal and the repeater interference signal in the time domain and frequency domain is avoided, thereby further improving the anti-interference ability. When performing signal processing at the receiving end, the correction of the initial phase factor can be achieved through phase compensation. Regarding phase compensation, it is a conventional technical means for those skilled in the art and will not be elaborated here.

[0053] Through the above analysis, it can be seen that the technical solution disclosed in the embodiments of the present invention can effectively counter spoofing interference and repeater interference.

[0054] In the existing field of radar-communication integration, when transmitting information, it is only limited to loading information through the amplitude, frequency, and phase parameters of the transmitted waveform, and the constraint of the information loading method is relatively large.

[0055] In order to further improve the information transmission efficiency of the system, the inventor abandoned the traditional way of loading data with parameters and explored the way of loading data with transmission waveforms. Three methods, namely orthogonal sequence selective mapping, orthogonal sequence phase shift mapping, and pulse amplitude modulation, are used to load information simultaneously, thus effectively improving the information transmission efficiency of the system.

[0056] In the technical solution disclosed in the embodiment of the present invention, orthogonal sequence selective mapping means that p-bit selective mapping groups in user data D(t) are respectively mapped to the i-th orthogonal sequence selected from N orthogonal sequences for modulation according to a one-to-one mapping relationship. Each data combination of the p-bit selective mapping group can only be mapped to one orthogonal sequence, and the orthogonal sequences mapped by any two data combinations are different from each other;

[0057] Orthogonal sequence phase shift mapping means that q-bit phase shift mapping groups in user data D(t) are respectively mapped to the cyclic shift states of the i-th orthogonal sequence according to a one-to-one mapping relationship. Each data combination of the q-bit phase shift mapping group can only be mapped to one cyclic shift state of the i-th orthogonal sequence, and the cyclic shift states mapped by any two data combinations are different from each other;

[0058] Pulse amplitude modulation means that each bit of data in the cyclic shift state of the i-th orthogonal sequence is sequentially loaded onto the prolate spheroidal wave function γ(c,t).

[0059] In this way, parameters such as orthogonal sequence selection, orthogonal sequence cyclic shift state, and pulse amplitude can be fully utilized to carry data simultaneously, thereby improving the information transmission efficiency of the system. Further, in order to reduce the peak-to-average ratio of the modulated signal, the time-domain superposition method of multi-carrier modulation technology is abandoned, and the integral form after block mapping and pulse amplitude modulation is used as the additional phase of the non-linear frequency modulation signal, so that the non-linear frequency modulation signal has a constant envelope characteristic. When transmitted to the channel, the radar system has high power utilization efficiency and can detect targets at a long distance, solving the problem of reduced radar performance caused by high peak ratio in the prior art.

[0060] When loading data with pulse amplitude, the pulse form has a great influence on the main lobe energy concentration of the modulated signal; the better the energy concentration of the main lobe, the better the target detection performance, and vice versa, the worse.

[0061] Prolate Spheroidal Wave Functions (PSWFs) satisfy the following integral equation within a given time interval [-T / 2, T / 2]:

[0062]

[0063] where λ n (c) is the n-th order prolate spheroidal wave function γn (c,t) corresponds to the eigenvalue, which is used to represent the energy concentration factor, n is the order, Ω is the angular frequency, and c is the time-bandwidth product factor. Because of its characteristics such as the best energy aggregation, it has a wide range of applications. In the technical solution disclosed in the embodiments of the present invention, the pulse waveform participating in pulse amplitude modulation adopts the prolate spheroidal wave function γ n (c,t); preferably, the γ n (c,t) is the 0th-order prolate spheroidal wave function, and the time-bandwidth product factor is c = 4π. At this time, the main lobe energy aggregation of the modulation signal can reach more than 99%. When used for channel transmission, it has strong anti-interference ability. Moreover, the γ n (c,t) also has the characteristic of large time bandwidth, and its high energy aggregation makes it beneficial to improve the resolution of the detected target when used in the radar field.

[0064] Preferably, in the technical solution disclosed in the embodiments of the present invention, the γ n (c,t) is the 0th-order prolate spheroidal wave function, and the time-bandwidth product factor is c = 4π.

[0065] Furthermore, in the technical solution disclosed in the embodiments of the present invention, the first information loading is completed through orthogonal sequence selection mapping. The orthogonal sequence selection mapping refers to selecting a certain orthogonal sequence from N orthogonal sequences to participate in modulation. Which orthogonal sequence is selected from N orthogonal sequences to participate in modulation is unknown and has a certain probability, so that information can be carried. For example, when selecting a certain orthogonal sequence from 4 kinds of orthogonal sequences, the probability of any one orthogonal sequence appearing is one-fourth. According to information theory, two bits of information can be carried, that is In the technical solution disclosed in the embodiments of the present invention, when performing orthogonal sequence selection mapping, according to the one-to-one mapping relationship, each data combination of the p-bit selection mapping group is respectively mapped to select the i-th orthogonal sequence from N orthogonal sequences to participate in modulation, and the p and N satisfy the relationship: The symbol represents rounding down. When N = 4, p = 2.

[0066] Preferably, in the technical solution disclosed in the embodiments of the present invention, the N orthogonal sequences are bipolar orthogonal sequences, pairwise orthogonal or quasi-orthogonal, and the number of bits is M.

[0067] In the prior art, when orthogonal sequences are involved in modulation to load information, usually two states, i.e., the positive phase and the negative phase of the orthogonal sequences, are used to carry information. Therefore, only 1 bit of information can be carried. In order to further improve the information-carrying capacity of the system and improve the information transmission efficiency, in the technical solution disclosed in the embodiments of the present invention, the two states of the positive phase and the negative phase of the sequence in the prior art are abandoned, and the cyclic shift states of the orthogonal sequences are used to load information, so as to increase the number of states and improve the information-carrying capacity. The orthogonal sequences after selective mapping are cyclically shifted, and the second information loading, i.e., phase shift mapping, is realized by using the cyclic shift states. The cyclic shift is a cyclic left shift or a cyclic right shift, and 1 bit of data is cyclically shifted each time. In the technical solution disclosed in the embodiments of the present invention, according to a one-to-one mapping relationship, each data combination of the q-bit phase shift mapping group is mapped to the cyclic left shift state of the i-th orthogonal sequence. Each data combination of the q-bit phase shift mapping group can only be mapped to one cyclic left shift state of the i-th orthogonal sequence, and the cyclic left shift states mapped by any two data combinations are different. Further, q and M satisfy the relational expression: Symbol represents rounding down. For example, if the number of bits of the orthogonal sequence after selective mapping is 8, i.e., M = 8, then q = 3.

[0068] Further, in the technical solution disclosed in the embodiments of the present invention, the data D(t) to be transmitted by the user is grouped. The grouping includes a p-bit selective mapping group Y(t) = {y1(t), y2(t), …, y p (t)} and a q-bit phase shift mapping group A(t) = {a1(t), a2(t), …, a q (t)}; that is, the data D(t) to be transmitted by the user is grouped according to the size of (p + q) bits. The grouping includes a p-bit selective mapping group and a q-bit phase shift mapping group.

[0069] Preferably, in the technical solution disclosed in the embodiments of the present invention, 4 bipolar orthogonal sequences are provided, denoted as c1(t), c2(t), c3(t), and c4(t). The 4 orthogonal sequences all contain 8 bits of data. For example, the orthogonal sequence c2(t) is -1, 1, 1, 1, 1, 1, -1, -1. After the orthogonal sequence c2(t) is cyclically shifted, 8 orthogonal sequences can be formed, which are respectively denoted as c 2,0 (t), c 2,1 (t), c 2,2 (t), c 2,3 (t), c 2,4 (t), c 2,5 (t), c 2,6 (t), c 2,7 (t).

[0070] Preferably, in the technical solution disclosed in the embodiments of the present invention, the data D(t) to be transmitted by the user is grouped according to the size of (2 + 3) bits. The grouping includes a 2-bit selection mapping group and a 3-bit phase shift mapping group. According to the one-to-one mapping relationship, each data combination of the 2-bit selection mapping group is respectively mapped to select an orthogonal sequence from the 4 orthogonal sequences to participate in modulation. Each data combination of the 2-bit selection mapping group can only be mapped to one orthogonal sequence, and its mapping relationship is shown in Table 1.

[0071] Table 1 Mapping relationship between data combinations of the selection mapping group and orthogonal sequences

[0072] <![CDATA[Data combinations y1(t) and y2(t) of the 2-bit selection mapping group]]> Orthogonal sequence 00 <![CDATA[c1(t)]]> 01 <![CDATA[c2(t)]]> 10 <![CDATA[c3(t)]]> 11 <![CDATA[c4(t)]]>

[0073] In the technical solution disclosed in the embodiments of the present invention, the one-to-one mapping relationship between the data combinations in the selection mapping group and the orthogonal sequences is not limited to Table 1, as long as each data combination in the selection mapping group has only one orthogonal sequence corresponding to it, and the orthogonal sequences corresponding to any two data combinations are different from each other.

[0074] As shown in Table 1, when the data combination of the 2-bit selection mapping group is 01, it is mapped to the second orthogonal sequence, that is, c2(t), thus completing the data loading of the selection mapping group, that is, representing the data combination with an orthogonal sequence. Generally speaking, the number of bits of the orthogonal sequence is greater than the number of bits of the data combination, thereby realizing spectrum spreading, reducing the power spectral density of the signal, improving the concealment ability of the signal, and making it difficult to be detected by reconnaissance equipment.

[0075] As mentioned above, when the orthogonal sequence c2(t) is -1, 1, 1, 1, 1, 1, -1, -1, after cyclic shift, 8 orthogonal sequences can be formed, which can be respectively expressed as c 2,0 (t), c 2,1 (t), c 2,2 (t), c 2,3 (t), c 2,4 (t), c 2,5 (t), c 2,6 (t), c 2,7 (t), where c 2,0 (t) = c 2,0 (t), that is, the initial state; on the basis of the selection mapping, the second information loading is completed through phase shift mapping.

[0076] According to the one-to-one mapping relationship, each data combination of the 3-bit phase shift mapping group is respectively mapped to the cyclic shift state of the second orthogonal sequence c2(t). Each data combination of the 3-bit phase shift mapping group can only be mapped to one cyclic shift state of the second orthogonal sequence c2(t). When the orthogonal sequence c2(t) uses cyclic left shift, the mapping relationship between the data combination of the phase shift mapping group and the cyclic shift state of the second orthogonal sequence c2(t) is shown in Table 2.

[0077] Table 2 Mapping relationship between data combination of phase shift mapping group and cyclic shift state of c2(t)

[0078]

[0079] In the technical solution disclosed in the embodiment of the present invention, the one-to-one mapping relationship between the data combination in the phase shift mapping group and the cyclic left shift state of the second orthogonal sequence c2(t) is not limited to Table 1. As long as each data combination in the phase shift mapping group has only one corresponding orthogonal sequence cyclic shift state, and the orthogonal sequence cyclic shift states corresponding to any two data combinations are different from each other.

[0080] As shown in Table 2, when the data combination of the phase shift mapping group is 001, it is mapped to the second cyclic shift state of the second orthogonal sequence c2(t) at this time, that is, c 2,1 (t). At this time, the values of each bit of the sequence c 21 (t) can be respectively expressed as:

[0081]

[0082] In the technical solution disclosed in the embodiment of the present invention, after completing the selection mapping and phase shift mapping information loading, pulse amplitude modulation is then used to load each bit of data of the second cyclic left shift state c 2,1 (t) of the second orthogonal sequence c2(t) onto the prolate spheroidal wave function γ0(c,t) in sequence, and its integral form is used as the additional phase of the exponential non-linear frequency modulation signal to form a radar-communication integrated modulation signal, that is:

[0083]

[0084] where, f c is the carrier frequency of the radar-communication integrated modulation signal, is the exponential non-linear frequency modulation factor, B is the signal bandwidth factor, is the second cyclic left shift state c of the second orthogonal sequence c2(t) participating in modulation 2,1The j-th bit data of (t), where j is a positive integer, j = 1, 2, … 8, γ0(c, t) is the zero-order prolate spheroidal wave function, and the c is the time-bandwidth product factor. The formed modulation signal has the characteristics of constant envelope and low peak-to-average ratio, improves the power utilization rate of the radar power amplifier system, ensures the detection performance of the radar for targets, expands the signal spectrum at the same time, improves the concealment ability of the radar signal, improves the ability to resist deceptive interference, and can convert the repeater interference into low-power spectral noise, significantly improving the anti-interference ability. On this basis, it also improves the information transmission efficiency of the system and solves the problems existing in the prior art.

[0085] Although the embodiments of the present invention have been disclosed as above, they are not limited to the usage modes listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated and described examples here.

Claims

1. An anti-interference radar communication integrated signal design method, characterized in that The integrated radar communication signal is as follows: where, f c is the carrier frequency of the integrated radar and communication signal, is the exponential non-linear frequency modulation factor, B is the signal bandwidth factor, is the j-th bit data of the k-th cyclic shift state of the i-th orthogonal sequence participating in modulation, j is a positive integer, j = 1, 2, … M, where M is the total number of bits of the orthogonal sequence, k is a positive integer, k = 0, 1, 2, … M-1, θ(j) is the initial phase factor, γ n (c, t) is the prolate spheroidal wave function, n is the order of the prolate spheroidal wave function, and c is the time-bandwidth product factor.

2. The anti-interference radar communication integrated signal design method according to claim 1, wherein, Generating the integrated radar communication signal includes the following steps: Step 1: Group the data D(t) to be transmitted by the user. The grouping includes a p-bit selection mapping group Y(t) = {y1(t), y2(t),..., y p (t)} and a q-bit phase shift mapping group A(t) = {a1(t), a2(t),..., a q (t)}; Step 2: According to a one-to-one mapping relationship, each data combination of the p-bit selection mapping group is respectively mapped to select the i-th orthogonal sequence from N orthogonal sequences to participate in modulation. Each data combination of the p-bit selection mapping group can only be mapped to one orthogonal sequence, and the orthogonal sequences mapped by any two data combinations are different from each other; Step 3: According to a one-to-one mapping relationship, each data combination of the q-bit phase shift mapping group is respectively mapped to the cyclic shift state of the i-th orthogonal sequence. Each data combination of the q-bit phase shift mapping group can only be mapped to one cyclic shift state of the i-th orthogonal sequence, and the cyclic shift states of the orthogonal sequences mapped by any two data combinations are different from each other; Step 4: By using pulse amplitude modulation, each bit of data in the \(i\)-th cyclic shift state of the orthogonal sequence is successively loaded onto the prolate spheroidal wave function \(\gamma(c, t)\), and its integral form is used as the additional phase of the exponential frequency-modulated signal to form an integrated radar and communication modulation signal. n (c,t), and its integral form is used as the additional phase of the exponential frequency-modulated signal to form an integrated radar and communication modulation signal.

3. The anti-interference radar communication integrated signal design method according to claim 2, wherein, The initial phase factor θ(j) is as follows: where j is a positive integer, j = 1, 2, … N.

4. The anti-interference radar communication integrated signal design method according to claim 2, wherein The N orthogonal sequences are pairwise orthogonal or quasi-orthogonal, and each has a bit number of M.

5. The anti-interference radar communication integrated signal design method according to claim 2, wherein The p and N satisfy the relational expression: The symbol represents rounding down.

6. The anti-interference radar communication integrated signal design method according to claim 2, characterized in that The q and M satisfy the relation: The symbol represents rounding down.

7. The anti-interference radar communication integrated signal design method according to claim 1, characterized in that The said γ n (c,t) is the zero-order prolate spheroidal wave function, and the time-bandwidth product factor is c = 4π.

8. The anti-interference radar communication integrated signal design method according to claim 1, wherein The cyclic shift is a cyclic left shift or a cyclic right shift, and each time 1-bit data is cycled.

9. The anti-interference radar communication integrated signal design method according to claim 2, wherein The N orthogonal sequences are bipolar orthogonal sequences.

10. The anti-interference radar communication integrated signal design method according to claim 2, wherein The data D(t) to be transmitted by the user is grouped by 5 bits, and the grouping includes a 2-bit selection mapping group and a 3-bit phase shift mapping group.

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