CN116008920A - Anti-interference radar communication integrated signal design method - Google Patents
Anti-interference radar communication integrated signal design method Download PDFInfo
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Abstract
The invention relates to a radar communication integrated signal design method with broadband anti-interference capability, and belongs to the field of radar communication integration. In the invention, user data are grouped into p-bit selection mapping groups and q-bit shift mapping groups, each data combination of the p-bit selection mapping groups is mapped into an i-th orthogonal sequence selected from N orthogonal sequences to participate in modulation according to a one-to-one mapping relation, each data combination of the q-bit shift mapping groups is mapped into a cyclic shift state of the i-th orthogonal sequence, pulse amplitude modulation is adopted, each data of the cyclic shift state of the i-th orthogonal sequence is sequentially loaded onto a long spherical wave function, and an integral form of the data combination is used as an additional phase of an exponential nonlinear frequency modulation signal to form a radar communication integrated modulation signal. According to the technical scheme disclosed by the invention, the anti-interference capability, the information transmission capability and the power utilization rate of the radar communication integrated modulation signal are improved.
Description
Technical Field
The invention relates to a radar communication integrated signal design method with broadband anti-interference capability, and belongs to the field of radar communication integration.
Background
The radar communication integration mainly realizes information transmission through communication sharing radar resources, and the integrated shared signal can transmit information while detecting and positioning targets, thereby completing 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 is on the design method of the integrated shared signal and the modulation and demodulation technology of the signal. With the rapid development of modern electronics, electronic warfare has become a new battlefield in modern warfare.
The integrated waveform of radar communication is designed based on OFDM, and is a research hotspot in the integrated field of the existing radar communication. The technology utilizes the high information transmission rate of the OFDM modulation signal to improve the transmission rate of the system, and meanwhile, when the OFDM modulation signal is used in a radar system, the OFDM modulation signal has the characteristic of long-time bandwidth product signal, so that the requirements of high resolution and high resolution of distance of radar detection targets can be met. However, the inherent peak average bit property of the OFDM greatly reduces the power utilization rate of the system, thereby reducing the distance of the radar system to target detection and seriously affecting the working performance of the radar system.
In the field of radar communication integration, it is very important to improve the validity of a radar communication integration system and the anti-electronic interference capability of the system, and important indexes such as flexibility, reliability and the like of a detected target are related. The high-tech electronic equipment such as radar, communication, electronic countermeasure and the like is used for carrying the tasks of information acquisition, networking transmission, electromagnetic use right competition and the like, and is a core element of an electronic countermeasure system under the informatization condition. In the 90 s of the 20 th century, along with the development of radar electronic countermeasure technologies, especially the rapid development of active interference technologies based on digital radio frequency memories, radar communication integrated signals can have adaptability in complex electromagnetic environments, which brings serious challenges to the design of the radar communication integrated signals.
Therefore, how to improve the information transmission efficiency and the power efficiency of the system simultaneously on the premise of improving the anti-interference capability of the radar communication integrated signal is a difficult problem to be solved by the existing radar communication integrated signal design.
Disclosure of Invention
The invention aims to solve the defects in the prior art, and provides the integrated design method for the radar communication, which can improve the information transmission efficiency and the power efficiency of the system on the premise of improving the anti-interference capability of the integrated signal of the radar communication.
In order to achieve the purpose of the invention, the invention provides an anti-interference radar communication integrated signal design method, which is characterized in that in the method, the radar communication integrated signal is as follows:
wherein f c The carrier frequency of the signal is modulated for the radar communication integration,
is exponential nonlinear frequency modulation factor, B is signal bandwidth factor, < ->
J is a positive integer, j=1, 2, … M, wherein M is the total bit number of the ith orthogonal sequence, k is a positive integer, k=0, 1,2, … M-1, θ (j) is an initial phase factor, and γ n (c, t) is a long sphereThe wave function, n, is the order of the long spherical wave function, and c is the time-bandwidth product factor. />
Further, the radar communication integrated signal comprises the following design steps:
step one: grouping data D (t) to be transmitted by a user, wherein the grouping comprises p-bit selection mapping groups Y (t) = { Y 1 (t),y 2 (t),…,y p (t) } and q-phase shift mapping group a (t) = { a 1 (t),a 2 (t),…,a q (t)}；
Step two: according to a one-to-one mapping relation, mapping each data combination of the p-bit selection mapping group to select an ith orthogonal sequence from N orthogonal sequences to participate in modulation, wherein each data combination of the p-bit selection mapping group can be mapped with only one orthogonal sequence, and the orthogonal sequences mapped by any two data combinations are different;
step three: according to a one-to-one mapping relationship, mapping each data combination of the q-phase shift mapping group into a cyclic shift state of the ith orthogonal sequence, wherein each data combination of the q-phase shift mapping group can only be mapped with one cyclic shift state of the ith orthogonal sequence, and the cyclic shift states of the orthogonal sequences mapped by any two data combinations are different;
step four: sequentially loading each bit of data in the ith orthogonal sequence cyclic shift state to the long spherical wave function gamma by adopting pulse amplitude modulation n And (c, t) and taking the integrated form as the additional phase of the exponential nonlinear frequency modulation signal to form the radar communication integrated modulation signal.
Further, the initial phase factor θ (j) is:
j is a positive integer, j=1, 2, … N.
Further, the N orthogonal sequences are orthogonal or quasi-orthogonal in pairs, and the number of bits is M.
Further, the p and N satisfy the relation:
sign->
Representing a rounding down.
Further, q and M satisfy the relation:
sign->
Representing a rounding down.
Preferably, the gamma n (c, t) is a 0 th order long spherical wave function, and the time-bandwidth product factor is c=4pi.
Preferably, the cyclic shift is cyclic left shift or cyclic right shift, and each cycle shifts 1bit of data.
Preferably, the N orthogonal sequences are bipolar orthogonal sequences.
Preferably, the data D (t) to be transmitted by the user is grouped according to a size of 5 bits, and the grouping includes a 2-bit selection mapping group and a 3-bit phase shift mapping group.
Compared with the prior art, the invention has the following beneficial effects:
(1) The power utilization rate of the system is improved.
In the technical scheme disclosed by the invention, the pulse waveform for completing data loading adopts an integral form as an additional phase of an exponential nonlinear frequency modulation signal, so that the radar communication integrated waveform design is realized, and the integrated modulation signal has constant envelope characteristics. Therefore, compared with the prior art, the power utilization rate of the radar system can be effectively improved, and the acting distance for target detection is enhanced.
(2) The anti-interference capability of the system is improved.
In the technical scheme disclosed by the invention, the information to be transmitted is loaded on the orthogonal sequence by adopting the modes of orthogonal sequence selection mapping and orthogonal sequence phase shift mapping, so that the spectrum spreading is realized, the power spectrum density of the radar communication integrated modulation signal is reduced, and the concealment is improved; further, by adopting a mode of combining orthogonal sequence selection and initial phase factors, radar communication integrated signals are prevented from being accumulated in a coherent mode with forwarding type interference signals in a time domain and a frequency domain; further, because the orthogonal sequences mapped by different data packets are different, the receiving system can convert the interference signals carrying different orthogonal sequences into low-power spectral noise signals by utilizing the orthogonality or quasi-orthogonality of the orthogonal sequences, and can effectively inhibit the forward interference, thereby improving the anti-interference capability.
(3) And the information transmission efficiency of the system is improved.
In the technical scheme disclosed by the invention, the traditional mode of loading information only by adopting amplitude parameters is abandoned, the way of transmitting waveform loading information is expanded, and information is simultaneously loaded by adopting three modes of orthogonal sequence selection mapping, orthogonal sequence phase shift mapping and pulse amplitude modulation, so that the information transmission efficiency of the system is effectively improved.
(4) The signal-to-interference ratio of the radar communication integrated signal is improved.
In the prior art, a linear frequency modulation signal is often adopted to design a radar communication integrated signal, the signal has larger side lobes, and when the side lobes are restrained by a filter, the radar modulation signal can generate serious waveform distortion, so that the anti-interference capability of the radar signal in the channel transmission process is reduced. In the technical scheme disclosed by the invention, the nonlinear frequency domain characteristic is constructed by adopting an exponential manner, so that the purpose of reducing the amplitude of a side lobe of a radar modulation signal is achieved, the signal distortion generated when the side lobe is restrained is reduced, the signal-to-interference ratio of the radar signal is improved, the radar signal has stronger electromagnetic interference resistance in the channel transmission process, and the reliability of radar communication integrated modulation signal transmission is improved.
Drawings
Fig. 1 is a schematic diagram of radar communication integrated modulation signal generation according to an embodiment of the present invention.
Detailed Description
The present invention is described in further detail below with reference to examples and drawings to enable those skilled in the art to practice the same and to refer to the description.
In the prior art, when the OFDM technology is used for designing radar communication integrated signals, the inherent peak-to-average ratio characteristic of the OFDM technology greatly reduces the power utilization rate of the system, thereby reducing the distance of the radar system to target detection and seriously affecting the working performance of the radar system. Although the peak-to-average ratio of the modulation signal can be relieved to a certain extent by adopting the method for reducing the peak-to-average ratio, the peak-to-average ratio of the modulation signal is still changed in a fluctuation in a larger range, so that the problem cannot be fundamentally solved. The peak average bit property reduces the power utilization rate of the radar communication integrated system, so that the power of a signal transmitted by a transmitter is limited, and the interference resistance is reduced.
Compared with the OFDM technology, the linear frequency modulation signal has constant envelope characteristic, ensures the power efficiency of the system, has wider spectrum bandwidth, and can improve the resolution ratio when being used for detecting targets. However, the linear frequency modulation signal has larger frequency spectrum sidelobes, and when the sidelobes are suppressed by filtering, the modulation signal can generate serious waveform distortion, so that the SNR (signal to noise ratio) of the signal is reduced, the anti-interference capability of the signal in the channel transmission process is reduced, and the application environment of the signal is limited.
Along with the development of radar electronic countermeasure technology, especially the rapid development of active interference technology based on digital radio frequency memory, the adaptability of radar communication integrated signals in complex electromagnetic environment is challenged, and the anti-interference capability of the radar communication integrated signals must be improved.
In order to solve the problem and improve the anti-interference capability of radar communication integrated signals, the invention discloses an anti-interference radar communication integrated signal design method. In the technical scheme disclosed by the embodiment of the invention, the modulation signal adopts exponential type construction nonlinear frequency domain characteristics to construct a nonlinear frequency modulation radar modulation signal, namely
Wherein f c The carrier frequency of the signal is modulated for the radar communication integration,
the digital signal is an exponential type nonlinear frequency modulation factor, B is a signal bandwidth factor, j is a positive integer, and the digital bit number is represented. The exponential frequency domain characteristic enables the radar modulation signal to present nonlinear characteristic, so as to achieve the purpose of reducing the amplitude of a side lobe of the radar modulation signal, reduce signal distortion generated when the radar signal is radiated through antenna filtering, and accordingly improve the SNR (signal to noise ratio) of the radar modulation signal, enable the radar modulation signal to have stronger electromagnetic interference resistance in the channel transmission process, and further expand the applicable application environment.
Therefore, the embodiment of the invention adopts the non-linear frequency modulation signal to design the radar signal, so that the transmission reliability can be improved, and on the basis, the radar signal and the communication modulation signal are integrally designed to achieve better radar detection performance and data transmission performance.
In the field of radar electronic countermeasure, spoofing, and repeated interference are one of the common types of interference. The deceptive jamming is to intercept the interfered signal by interception equipment, analyze the signal characteristics of the interfered signal to obtain signal parameters, and release deceptive jamming signals with similar parameters by the jammer on the basis of the signal parameters so as to implement jamming. Thus, the premise of effective implementation of such interference is to obtain radar signal parameters. Compared with deception jamming, the forwarding jamming does not need to obtain radar signal parameters, and the purpose of implementing jamming is achieved by amplifying the power of a received interfered signal and forwarding the amplified signal to a interfered system.
In order to effectively resist deception jamming and forwarding jamming, the embodiment of the invention discloses an anti-jamming radar communication integrated signal design method. In the method, the radar communication integrated modulation signal is:
wherein f c The carrier frequency of the signal is modulated for the radar communication integration,
is exponential nonlinear frequency modulation factor, B is signal bandwidth factor, < ->
J is a positive integer, j=1, 2, … M, wherein 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, and γ n (c, t) is a long spherical wave function, n is the order of the long spherical wave function, and c is a time-bandwidth product factor.
Further, as shown in fig. 1, in the technical solution disclosed in the embodiment of the present invention, generating the radar communication integrated modulation signal includes the following steps:
step one: grouping data D (t) to be transmitted by a user, wherein the grouping comprises p-bit selection mapping groups Y (t) = { Y 1 (t),y 2 (t),…,y p (t) } and q-phase shift mapping group a (t) = { a 1 (t),a 2 (t),…,a q (t)}；
Step two: according to a one-to-one mapping relation, mapping each data combination of the p-bit selection mapping group to select an ith orthogonal sequence from N orthogonal sequences to participate in modulation, wherein each data combination of the p-bit selection mapping group can be mapped with only one orthogonal sequence, and the orthogonal sequences mapped by any two data combinations are different;
step three: according to a one-to-one mapping relationship, mapping each data combination of the q-phase shift mapping group into a cyclic shift state of the ith orthogonal sequence, wherein each data combination of the q-phase shift mapping group can only be mapped with one cyclic shift state of the ith orthogonal sequence, and the cyclic shift states mapped by any two data combinations are different;
step four: by means of pulsesAmplitude modulation, loading each bit of data of the ith orthogonal sequence cyclic shift state to the long spherical wave function gamma in turn n And (c, t) and taking the integrated form as the additional phase of the exponential nonlinear frequency modulation signal to form the radar communication integrated modulation signal.
In the technical scheme disclosed by the embodiment of the invention, the data D (t) to be transmitted by a user are grouped, and the data to be transmitted are mapped into the orthogonal sequence c by selecting a mapping mode and a phase shift mapping mode i (t) the orthogonal sequence c i The number of bits M of (t) is greater than the number of bits of the data packet, i.e. the orthogonal sequence c i The chip duration in (t) is smaller than the data duration in the data packet, after mapping is completed according to the transformation relation between duration and frequency spectrum, frequency spectrum widening is realized, and the effect of frequency spreading is achieved, so that the power spectrum density of a signal is reduced, the hiding capacity of the signal is improved, the waveform parameters of radar communication integrated signals are difficult to obtain by reconnaissance equipment, and deception jamming is difficult to effectively implement.
Further, in the technical solution disclosed in the embodiment of the present invention, each data combination of the p-bit selection mapping group is mapped to select an ith orthogonal sequence from N orthogonal sequences to participate in modulation, that is, orthogonal sequences mapped by different data combinations of the selection mapping group are different, so that orthogonal sequences adopted between different data packets are different and mutually orthogonal or quasi-orthogonal; the method has the advantages that the forward interference is difficult to effectively interfere the signals crossing the data packets, because the orthogonal sequences adopted by different data packets are different and meet the two-to-two orthogonal or quasi-orthogonal relation, the radar communication integrated receiving system can receive useful signals according to the correlation matching of the orthogonal or quasi-orthogonal relation among different sequences, and for the forward interference signals, the receiving system can convert the interference signals carrying different orthogonal sequences into low-power spectrum noise signals by utilizing the orthogonality or quasi-orthogonality, so that the forward interference can be effectively restrained. If efficient forward interference is to be implemented, the whole process of forwarding the interference must be completed within one data packet time, and one data packet time is extremely short, which forces the forward interference platform to be very close to the interfered platform, which is difficult to achieve in a practical battlefield environment.
Further, in the technical scheme disclosed in the embodiment of the invention, in order to further prevent the radar communication integrated signal from coherently accumulating with the forwarding type interference signal in the time domain and the frequency domain, the integrated signal is further provided with a primary phase factor θ (j), and the primary phase factor θ (j) is:
j is a positive integer, j=1, 2, … M, namely the initial phase size is closely related to the number of bits of the orthogonal sequence, and the initial phases among the numbers of bits are different, so that the phase diversity between the integrated signal and the forwarding interference is further increased. The mode of combining the orthogonal sequence and the initial phase factor is adopted, so that the coherent accumulation of radar communication integrated signals and forwarding type interference signals in time domain and frequency domain is avoided, and the anti-interference capability is further improved. When the receiving end processes signals, the correction of the initial phase factor can be realized through phase compensation. The phase compensation is a common technical means for those skilled in the art, and will not be described in detail herein.
According to the analysis, the technical scheme disclosed by the embodiment of the invention can effectively resist deception interference and forwarding interference.
In the existing radar communication integrated field, when information transmission is carried out, the information is loaded only through the parameters of amplitude, frequency and phase of a transmission waveform, and the information loading mode has high constraint.
In order to further improve the information transmission efficiency of the system, the inventor discards the traditional mode of loading data by parameters and expands the way of transmitting waveform loading data. The information is loaded simultaneously by adopting three modes of orthogonal sequence selection mapping, orthogonal sequence phase shift mapping and pulse amplitude modulation, so that the information transmission efficiency of the system is effectively improved.
In the technical scheme disclosed by the embodiment of the invention, the orthogonal sequences are selected and mapped, namely p-bit selection and mapping groups in the user data D (t) are respectively mapped to select an ith orthogonal sequence from N orthogonal sequences to participate in modulation according to a one-to-one mapping relation, each data combination of the p-bit selection and mapping groups can be mapped with one orthogonal sequence only, and the orthogonal sequences mapped by any two data combinations are different;
the q-phase shift mapping in the user data D (t) is mapped to the cyclic shift state of the ith orthogonal sequence according to a one-to-one mapping relationship, each data combination of the q-phase shift mapping group can only be mapped with one cyclic shift state of the ith orthogonal sequence, and the cyclic shift states mapped by any two data combinations are different;
pulse amplitude modulation, namely loading each bit of data in the cyclic shift state of the ith orthogonal sequence to a long spherical wave function gamma (c, t) in sequence.
Therefore, parameters such as orthogonal sequence selection, orthogonal sequence cyclic shift state, pulse amplitude and the like can be fully utilized to carry data, and the information transmission efficiency of the system is improved. Furthermore, in order to reduce the peak-to-average ratio of the modulation signal, a time domain superposition mode of a multi-carrier modulation technology is abandoned, an integral form after grouping mapping and pulse amplitude modulation is used as an additional phase of a nonlinear frequency modulation signal, so that the nonlinear frequency modulation signal has constant envelope characteristics, the power utilization rate of a radar system is high when the nonlinear frequency modulation signal is transmitted to a channel, the detection target distance is long, and the problem of radar performance reduction caused by the peak-to-average ratio in the prior art is solved.
When the pulse amplitude is used for loading data, the main lobe energy aggregation of the modulated signal is greatly influenced by the pulse form; the better the energy concentration of the main lobe, the better the detection target performance, and conversely, the worse.
The long spherical wave function (Prolate Spheroidal Wave Functions, PSWFs) satisfies the following integral equation over a given time interval [ -T/2, T/2 ]:
wherein lambda is n (c) For the n-order long spherical wave function gamma n And (c, t) corresponding characteristic values for representing the energy concentration factor, wherein n is an order, Ω is an angular frequency, and c is a time bandwidth product factor. The energy collector has the characteristics of optimal energy aggregation and the like, so that the energy collector has wide application. In the technical scheme disclosed by the embodiment of the invention, the pulse waveform participating in pulse amplitude modulation adopts a long spherical wave function gamma n (c, t); preferably, the gamma n And (c, t) is a 0-order long spherical wave function, the time bandwidth product factor is c=4pi, and at the moment, the main lobe energy aggregation of the modulation signal can reach more than 99 percent, and the modulation signal has stronger anti-interference capability when being used for channel transmission. Furthermore, the gamma n (c, t) also has a large time-bandwidth characteristic, and has high energy aggregation, so that the resolution of a detected target is improved when the radar is used in the radar field.
Preferably, in the technical solution disclosed in the embodiments of the present invention, the γ n (c, t) is a 0 th order long spherical wave function, and the time-bandwidth product factor is c=4pi.
Further, in the technical scheme disclosed by the embodiment of the invention, the 1 st information loading is completed through the orthogonal sequence selection mapping. The orthogonal sequence selection mapping refers to selecting a certain orthogonal sequence from N orthogonal sequences to participate in modulation. It is unknown which orthogonal sequence is selected from the N orthogonal sequences to participate in modulation, and it has a certain probability, so that information can be carried. For example, a certain orthogonal sequence is selected from 4 kinds of orthogonal sequences, the probability of any one orthogonal sequence is one fourth, and two bits of information can be carried as known from information theory, namely
In the technical scheme disclosed by the embodiment of the invention, when orthogonal sequence selection mapping is performed, each data combination of the p-bit selection mapping group is mapped to select an ith orthogonal sequence from N orthogonal sequences to participate in modulation according to a one-to-one mapping relation, and the p and the N satisfy a relation: />
Sign->
Representing a rounding down. When n=4, p=2.
Preferably, in the technical solution disclosed in the embodiment of the present invention, the N orthogonal sequences are bipolar orthogonal sequences, two-by-two orthogonal or quasi-orthogonal, and the number of bits is M.
In the prior art, the orthogonal sequence participates in modulating and loading information, and normally, information is carried by utilizing two states of normal phase and reverse phase of the orthogonal sequence, so that only 1bit 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 scheme disclosed by the embodiment of the invention, two states of normal phase and reverse phase of a sequence in the prior art are abandoned, and the information is loaded by utilizing the cyclic shift state of an orthogonal sequence so as to increase the number of states and improve the information carrying capacity. And performing cyclic shift on the orthogonal sequence after the mapping is selected, and realizing the information loading of the 2 nd time, namely phase shift mapping by utilizing the cyclic shift state. The cyclic shift is a cyclic left shift or cyclic right shift, each cycle shifting 1bit of data. In the technical scheme disclosed in the embodiment of the invention, each data combination of the q-phase shift mapping group is mapped to the cyclic left shift state of the ith orthogonal sequence according to a one-to-one mapping relationship, each data combination of the q-phase shift mapping group can only be mapped with one cyclic left shift state of the ith orthogonal sequence, and the cyclic left shift states mapped by any two data combinations are different. Further, q and M satisfy the relation:
sign->
Representing a rounding down. For example, by selecting the number of bits of the mapped orthogonal sequence to be 8, i.e., m=8, q=3.
Further, in the present inventionIn the technical solution disclosed in the embodiment, data D (t) to be transmitted by a user is grouped, where the grouping includes p-bit selection mapping groups Y (t) = { Y 1 (t),y 2 (t),…,y p (t) } and q-phase shift mapping group a (t) = { a 1 (t),a 2 (t),…,a q (t) }; i.e. the data D (t) to be transmitted by the user is grouped according to the (p+q) bit size, said grouping comprising a p-bit selection map group and a q-bit shift map group.
Preferably, in the technical scheme disclosed in the embodiment of the present invention, 4 bipolar orthogonal sequences are provided, denoted as c 1 (t)、c 2 (t)、c 3 (t) and c 4 (t) the 4 orthogonal sequences each comprise 8 bits of data. For example, orthogonal sequence c 2 (t) is-1, -1, -1, orthogonal sequence c 2 (t) after cyclic shift, 8 orthogonal sequences can be formed, 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)。
Preferably, in the technical solution disclosed in the embodiment of the present invention, the data D (t) to be transmitted by the user is grouped according to the (2+3) bit size, where the grouping includes a 2bit selection mapping group and a 3bit phase shift mapping group. According to a one-to-one mapping relationship, each data combination of the 2bit selection mapping group is mapped to select a certain orthogonal sequence from the 4 orthogonal sequences to participate in modulation, and each data combination of the 2bit selection mapping group can be mapped with only one orthogonal sequence, and the mapping relationship is shown in table 1.
Table 1 mapping relation between data combinations of selected mapping groups and orthogonal sequences
| Data combination y of 2bit selection map group 1 (t)、y 2 (t) | Orthogonal sequences |
| 00 | c 1 (t) |
| 01 | c 2 (t) |
| 10 | c 3 (t) |
| 11 | c 4 (t) |
In the technical solution disclosed in the embodiment of the present invention, the one-to-one mapping relationship between the data combinations and the orthogonal sequences in the selection mapping group is not limited to table 1, as long as only one orthogonal sequence corresponding to each data combination in the selection mapping group can be satisfied, and the orthogonal sequences corresponding to any two data combinations are different from each other.
As shown in Table 1, when the data combination of the 2bit selection map group is 01, then the mapping is the 2 nd orthogonal sequence, i.e., c 2 (t) whereby the data loading of the selection map set is completed, i.e. the data combination is represented by an orthogonal sequence. In general, the number of bits of the orthogonal sequence is greater than the number of bits of the data combination, so that spectrum spreading is realized, the power spectrum density of the signal is reduced, the concealment capability of the signal is improved, and the signal is difficult to be detected by the detection device.
As described above, when the orthogonal sequence c 2 (t) is-1, -1, -1, and after cyclic shift, 8 orthogonal sequences can be formed, which can be expressed as c, respectively 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), wherein c 2,0 (t)＝c 2,0 (t), an initial state; and on the basis of the selection mapping, finishing the 2 nd information loading through the phase shift mapping.
According to a one-to-one mapping relation, mapping each data combination of the 3bit phase shift mapping group to the 2 nd orthogonal sequence c respectively 2 (t) a cyclic shift state, each data combination of the 3-bit phase shift mapping group being capable of being combined with only the 2 nd orthogonal sequence c 2 And (t) a cyclic shift state. The orthogonal sequence c 2 (t) combining the data of the phase shift map group with the 2 nd orthogonal sequence c using cyclic left shift 2 The mapping relation of the cyclic shift state of (t) is shown in table 2.
Table 2 phase shift map set data combinations and c 2 (t) cyclic shift state mapping relation
In the technical scheme disclosed in the embodiment of the invention, the data combination in the phase shift mapping group and the 2 nd orthogonal sequence c 2 The one-to-one mapping relationship of the cyclic left shift states of (t) is not limited to table 1, as long as each data combination in the phase shift mapping group can be satisfied that only one orthogonal sequence cyclic shift state corresponds to the data combination, and the orthogonal sequence cyclic shift states corresponding to any two data combinations are different.
As shown in Table 2, when the data combination of the phase shift mapping group is 001, the data combination is mapped to the 2 nd orthogonal sequence c 2 The 2 nd cyclic shift state of (t), i.e. c 2,1 (t) sequence c at this time 21 The numerical values of bits of (t) can be expressed as:
in the technical scheme disclosed by the embodiment of the invention, after finishing the selection mapping and the phase shift mapping information loading, the 2 nd orthogonal sequence c is modulated by adopting pulse amplitude modulation 2 The 2 nd cyclic left shift state c of (t) 2,1 Each bit of data of (t)
Sequentially loaded to the long spherical wave function gamma 0 (c, t) and taking the integrated form as the additional phase of the exponential nonlinear frequency modulation signal to form a radar communication integrated modulation signal, namely:
wherein f c The carrier frequency of the signal is modulated for the radar communication integration,
is exponential nonlinear frequency modulation factor, B is signal bandwidth factor, < ->
2 nd orthogonal sequence c for participating in modulation 2 The 2 nd cyclic left shift state c of (t) 2,1 The j-th bit of data of (t), j being a positive integer, j=1, 2, …, γ 0 (c, t) is a 0 th order long spherical wave function, and c is a 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 a radar power amplification system, ensures the detection performance of a radar on a target, expands the signal spectrum, improves the concealment capability of the radar signal, improves the anti-deception jamming capability, can convert the forward jamming into low-power spectral noise, obviously improves the anti-jamming capability, and also improves the information transmission efficiency of the system on the basis, thereby solving the problems existing in the prior art.
Although the embodiments of the present invention have been disclosed above, they are not limited to the modes of use listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Additional modifications will readily occur to those skilled in the art. Therefore, the invention is not to be limited to the specific details and illustrations shown and described herein, without departing from the general concepts defined in the claims and their equivalents.
Claims (10)
1. The design method of the anti-interference radar communication integrated signal is characterized in that the radar communication integrated signal is as follows:
wherein f c The carrier frequency of the signal is modulated for the radar communication integration,
is exponential nonlinear frequency modulation factor, B is signal bandwidth factor, < ->
J is a positive integer, j=1, 2, … M, wherein 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, and γ n (c, t) is a long spherical wave function, n is the order of the long spherical wave function, and c is a time-bandwidth product factor.
2. The method of designing an integrated signal for anti-interference radar communication according to claim 1, wherein generating the integrated signal for radar communication comprises the steps of:
step one: grouping data D (t) to be transmitted by a user, wherein the grouping comprises p-bit selection mapping groups Y (t) = { Y 1 (t),y 2 (t),...,y p (t) } and q-phase shift mapping group a (t) = { a 1 (t),a 2 (t),...,a q (t)}；
Step two: according to a one-to-one mapping relation, mapping each data combination of the p-bit selection mapping group to select an ith orthogonal sequence from N orthogonal sequences to participate in modulation, wherein each data combination of the p-bit selection mapping group can be mapped with only one orthogonal sequence, and the orthogonal sequences mapped by any two data combinations are different;
step three: according to a one-to-one mapping relationship, mapping each data combination of the q-phase shift mapping group into a cyclic shift state of the ith orthogonal sequence, wherein each data combination of the q-phase shift mapping group can only be mapped with one cyclic shift state of the ith orthogonal sequence, and the cyclic shift states of the orthogonal sequences mapped by any two data combinations are different;
step four: sequentially loading each bit of data in the ith orthogonal sequence cyclic shift state to the long spherical wave function gamma by adopting pulse amplitude modulation n And (c, t) and taking the integrated form as the additional phase of the exponential nonlinear frequency modulation signal to form the radar communication integrated modulation signal.
3. The method for designing an integrated signal for anti-interference radar communication according to claim 2, wherein the initial phase factor θ (j) is:
j is a positive integer, j=1, 2, … N.
4. The method for designing integrated signals for anti-interference radar communication according to claim 2, wherein the N orthogonal sequences are orthogonal or quasi-orthogonal in pairs, and the number of bits is M.
5. The integrated signal design method for anti-interference radar communication according to claim 2, wherein p and N satisfy the relation:
sign->
Representing a rounding down.
6. Anti-interference radar according to claim 2The communication integrated signal design method is characterized in that q and M satisfy the relation:
sign->
Representing a rounding down.
7. The method for designing integrated signal for anti-interference radar communication according to claim 1, wherein the γ n (c, t) is a 0 th order long spherical wave function, and the time-bandwidth product factor is c=4pi.
8. The integrated signal design method for anti-interference radar communication according to claim 1, wherein the cyclic shift is cyclic left shift or cyclic right shift, and each cyclic shift is performed by 1bit of data.
9. The integrated signal design method for anti-interference radar communication according to claim 2, wherein the N orthogonal sequences are bipolar orthogonal sequences.
10. The integrated signal design method for anti-interference radar communication according to claim 2, wherein the data D (t) to be transmitted by the user is grouped according to a size of 5 bits, and the grouping includes a 2bit selection mapping group and a 3bit phase shift mapping group.
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