A detection and identification method and system based on orthogonal coding and pseudo-random coding

Abstract

The present invention relates to the field of radar communication technology, and discloses a detection and identification method and system based on orthogonal coding and pseudo-random coding, wherein the method comprises: the detection device sets waveform parameters, generates and transmits a Chirp signal to a target device through a radar transmitter; the target device performs phase coding modulation on the incident Chirp signal through an electromagnetic metasurface, and then reflects the modulated Chirp signal; the detection device uses the Chirp signal obtained by the same modulation mode as the target device as a matched filter, performs matched filtering on the received echo signal, and calculates the distance of the target device; and then performs Fourier transform on the matched filtering results of different pulse echoes to realize coherent accumulation, thereby realizing radar detection and target identification. The present invention utilizes the good autocorrelation characteristics of pseudo-random codes and the good orthogonal characteristics of orthogonal coding, so that the detection device can identify our target and detect the distance, and can confuse the enemy detection device.

Description

Technical Field

[0001] The present invention relates to the field of radar communication technology, and in particular to a detection and identification method and system based on orthogonal coding and pseudo-random coding. Background Art

[0002] Radar and communication are two typical functions widely equipped in modern electronic equipment systems, respectively responsible for target detection and information transmission. Radar and communication integration improves the utilization rate of system resources. The initial radar and communication integration refers to the realization of unified carrying of radar and communication information by one channel, one antenna, and one signal under the conditions of sharing resources such as spectrum space, time, and energy through unified design at the signal channel and information level. Its initial research motivation comes from the exploration and utilization of space resources of confrontation platforms such as aircraft and ships. By sharing resources such as control and display data processing channels and RF front-ends, the platform volume occupied by electronic equipment such as radar communication can be greatly reduced. At this stage, some European and American countries have initially realized the original intention of this research, and gradually shifted the research focus to micro-integrated systems and electromagnetic signal integration. Based on ubiquitous low-cost micro-integrated systems, multifunctional integrated coordination of electromagnetic space can be realized, and then a new integrated idea for the future can be derived to achieve the goal of forming any function in parallel at any time, any place, and any frequency. Therefore, only by further realizing micro-integration and signal integration can integration be truly achieved.

[0003] Detection and identification are two essential requirements in modern information confrontation. Detection is often achieved through radar, while identification is mainly achieved through optoelectronics or secondary radar. The use of secondary radar to complete the identification function requires the cooperation of the interrogator and the transponder. Existing equipment that has both detection and identification functions usually needs to have two electromagnetic transceiver systems, radar and identification. If the radar and identification functions can be combined into one system, the load of the equipment can be reduced. At present, with the development and widespread application of drone technology, in the future, low-cost swarm drones will participate in information confrontation and become the norm. However, this type of platform is small in size, extremely limited in load, and large in number, and easy to wear. On the one hand, it is difficult to install traditional transponder equipment due to the platform's load capacity; on the other hand, due to the huge number of drones, ultra-low cost is its typical requirement. In response to the needs of this information confrontation environment, on the one hand, it is necessary to change the active identification method to the passive identification method and cancel the transponder on the target device; on the other hand, the radar and identification systems on the detection equipment can be combined. The electromagnetic metasurface can simultaneously control the spatial and frequency distribution of reflected echoes. The study modulates the identification coding signal in the radar echo, detects the time-varying scattering field and spectrum in the radar echo signal, and performs corresponding signal information processing, thereby accurately identifying the target's enemy attributes.

[0004] According to the different integration methods of radar and communication, the common waveform integration design can be roughly divided into integration based on radar waveform and integration based on communication waveform. The radar-based integrated waveform refers to a waveform based on radar waveform, on which communication data is modulated. The communication-based integrated waveform refers to a waveform based on communication waveform, which is used or transformed into a waveform that can be detected by radar. Given that the electromagnetic metasurface control system is used to modulate radar echoes, the radar communication integrated waveform design for this application scenario should adopt a design method based on radar waveform.

[0005] From the perspective of information modulation, the integrated waveform design based on radar can be divided into two types of methods to load communication information: inter-pulse coding modulation and intra-pulse coding modulation. Inter-pulse coding often uses modulation frequency and pulse repetition frequency coding modulation. This type of waveform parameter carries information inefficiently. Intra-pulse coding divides the pulse into multiple sub-pulses, and then performs amplitude, phase or frequency modulation. Current research includes LFM-BPSK, LFM-QPSK, LFM-MSK, LFM-CPM, etc. The central idea is to use the LFM waveform commonly used by radar as the carrier frequency of the communication signal, which is convenient for achieving target detection while taking into account information modulation, and improves the algorithm to ensure detection performance and improve communication rate. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a detection and identification method and system based on orthogonal coding and pseudo-random coding, which can achieve the purpose of reducing equipment load and low cost.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A detection and identification method based on orthogonal coding and pseudo-random coding, comprising:

[0009] Radar signal generation and transmission: The detection device sets the waveform parameters, generates and transmits the Chirp signal to the target device through the radar transmitter;

[0010] Radar signal echo modulation: The target device performs phase coding modulation on the incident Chirp signal through the electromagnetic metasurface, and then reflects the modulated Chirp signal; the phase coding modulation includes BPSK modulation of the Chirp signal through a number of mutually orthogonal binary coding sequences, and BPSK modulation of the Chirp signal after orthogonal coding phase modulation through pseudo-random coding;

[0011] Radar ranging and target identification: The detection device uses the Chirp signal obtained by the same modulation method as the target device as a matched filter to perform matched filtering on the received echo signal; the matched filtering result is normalized and a first threshold is set. The matched filter code corresponding to the peak value higher than the first threshold is the corresponding target device code, and the time domain position corresponding to the peak value indicates the time of receiving the reflected echo of the target device, thereby calculating the target device code and distance;

[0012] Radar speed measurement: Coherent accumulation is achieved by performing Fourier transform on the matched filtering results of different pulse echoes, and the peak value greater than the second threshold is found in the speed domain and the speed of the target device is calculated, thereby realizing radar detection and target recognition.

[0013] Furthermore, in the radar signal echo modulation, the Chirp signal is BPSK modulated by a plurality of mutually orthogonal binary coding sequences, including:

[0014] Set N Hadamard coding sequences of length N and orthogonal to each other , where i represents the i-th Hadamard code, n represents the n-th code element of the Hadamard code, , The value is -1 or 1;

[0015] Hadamard coding sequence The corresponding baseband signal It is expressed as:

[0016]

[0017] in, G represents the number of sampling points of each code element in the sequence, g Indicates the first g sampling points, represents the sampling time interval, represents a unit impulse signal;

[0018] The Chirp signal is BPSK modulated using mutually orthogonal Hadamard codes:

[0019]

[0020]

[0021] in, represents the Hadamard coded phase modulated Chirp signal, Indicates Chirp signal; Represents a rectangular pulse with a width of T, where T is the period. For time; Indicates the carrier frequency; is the linear FM modulation slope, B is the linear FM modulation bandwidth; " represents dot product, Represents an imaginary unit.

[0022] Furthermore, in the radar signal echo modulation, BPSK modulation is performed on the Chirp signal after orthogonal coding phase modulation by pseudo-random coding, including:

[0023] Set the pseudo code sequence of length P , the value is -1 or 1; the pseudo code sequence The corresponding baseband signal Expressed as:

[0024]

[0025] Among them, Q represents the number of sampling points of each code element in the sequence, p Indicates p Code elements, q Indicates the first q sampling points, Represents a unit impulse signal.

[0026] Use the baseband signal generated by pseudo-random coding to perform pseudo-random code phase modulation on the orthogonal coded phase modulation Chirp signal:

[0027]

[0028] in, The integrated signal obtained by pseudo-random code phase modulation is used as the echo modulation signal; ” represents the dot product.

[0029] Furthermore, the radar ranging and target identification includes:

[0030] The matched filtering method is used to compress and demodulate the echo signal to construct the echo modulation signal. The conjugate anti-fold signal As a matched filter , and perform matched filtering on the received echo signal:

[0031]

[0032] in, represents the matched filtering result using the y-th matched filter, Indicates mixed echo, represents the y-th matched filter, ” indicates convolution; N represents the number of electromagnetic metasurface targets, represents the echo delay of the i-th target, Represents the autocorrelation function of the echo signal and the transmitted signal; represents Gaussian white noise; when When the matched filtering result is at position The target peak appears at When , the matched filtering result will not have target peaks, thereby screening out the orthogonal coded signal corresponding to the target echo;

[0033] According to the matched filtering results, find the peak value and record the distance value at this time and the corresponding matched filter orthogonal coding .

[0034] Furthermore, the radar ranging and target identification also includes coherently accumulating the matched filtering results of different pulse echoes by the same matched filter to calculate the distance and speed information of the target device:

[0035] The matched filtering results of all pulses based on the same matched filter form a matrix with three dimensions: time, number of pulses and amplitude:

[0036]

[0037] Where u represents the pulse echo number, U represents the number of pulse echoes, and y represents the matched filter number; represents the matched filtering result of the y-th matched filter on the u-th pulse echo, represents the matched filtering result of the y-th matched filter on U pulses;

[0038] Pair Matrix The pulse number dimension is transformed by FFT to obtain , The t-axis corresponds to the distance dimension, and the v-axis corresponds to the speed dimension; by analyzing The t and v values ​​corresponding to the peak are used to convert the distance and speed of the target device.

[0039] A detection and identification system based on orthogonal coding and pseudo-random coding, comprising:

[0040] The detection device is configured to generate and transmit a Chirp signal to a target device through a radar transmitter; and use the Chirp signal obtained by the same modulation method as the target device as a matched filter to perform matched filtering on the received echo signal; the matched filtering result is normalized, and a first threshold is set, and the matched filter code corresponding to the peak value higher than the first threshold value is the corresponding target device code, and the time domain position corresponding to the peak value indicates the time of receiving the reflected echo of the target device, thereby calculating the target device code and distance; by performing Fourier transform on the matched filtering results of different pulse echoes to achieve coherent accumulation, find the peak value greater than the second threshold value in the speed domain and calculate the speed of the target device, thereby achieving radar detection and target identification;

[0041] The target device is configured to perform phase coding modulation on the incident Chirp signal through an electromagnetic metasurface, and then reflect the modulated Chirp signal; the phase coding modulation includes BPSK modulation of the Chirp signal through a plurality of mutually orthogonal binary coding sequences, and BPSK modulation of the orthogonally coded phase-modulated Chirp signal through pseudo-random coding.

[0042] Furthermore, the BPSK modulation of the Chirp signal by using a plurality of mutually orthogonal binary coding sequences comprises:

[0043] Set N Hadamard coding sequences of length N and orthogonal to each other , where i represents the i-th Hadamard code, n represents the n-th code element of the Hadamard code, , The value is -1 or 1;

[0044] Hadamard coding sequence The corresponding baseband signal It is expressed as:

[0045]

[0046] in, G represents the number of sampling points of each code element in the sequence, g Indicates the first g sampling points, represents the sampling time interval, represents a unit impulse signal;

[0047] The Chirp signal is BPSK modulated using mutually orthogonal Hadamard codes:

[0048]

[0049]

[0050] in, represents the Hadamard coded phase modulated Chirp signal, Indicates Chirp signal; Represents a rectangular pulse with a width of T, where T is the period. For time; Indicates the carrier frequency; is the linear FM modulation slope, B is the linear FM modulation bandwidth; " represents dot product, Represents an imaginary unit.

[0051] Furthermore, the target device performs BPSK modulation on the Chirp signal after orthogonal coding phase modulation through pseudo-random coding, including:

[0052] Set the pseudo code sequence of length P , the value is -1 or 1; the pseudo code sequence The corresponding baseband signal Expressed as:

[0053]

[0054] Among them, Q represents the number of sampling points of each code element in the sequence, p Indicates p Code elements, q Indicates the first q sampling points, Represents a unit impulse signal.

[0055] Use the baseband signal generated by pseudo-random coding to perform pseudo-random code phase modulation on the orthogonal coded phase modulation Chirp signal:

[0056]

[0057] in, The integrated signal obtained by pseudo-random code phase modulation is used as the echo modulation signal; ” represents the dot product.

[0058] Furthermore, the detection device uses a Chirp signal obtained by the same modulation mode as the target device as a matched filter to perform matched filtering on the received echo signal, including:

[0059] The matched filtering method is used to compress and demodulate the echo signal to construct the echo modulation signal. The conjugate anti-fold signal As a matched filter , and perform matched filtering on the received echo signal:

[0060]

[0061] in, represents the matched filtering result using the y-th matched filter, Indicates mixed echo, represents the y-th matched filter, ” indicates convolution; N represents the number of electromagnetic metasurface targets, represents the echo delay of the i-th target, Represents the autocorrelation function of the echo signal and the transmitted signal; represents Gaussian white noise; when When the matched filtering result is at position The target peak appears at When , the matched filtering result will not have target peaks, thereby screening out the orthogonal coded signal corresponding to the target echo;

[0062] According to the matched filtering results, find the peak value and record the distance value at this time and the corresponding matched filter orthogonal coding .

[0063] Furthermore, the detection device can perform coherent accumulation of matched filtering results of different pulse echoes through the same matched filter to calculate the distance and speed information of the target device, including:

[0064] The matched filtering results of all pulses based on the same matched filter form a matrix with three dimensions: time, number of pulses and amplitude:

[0065]

[0066] Where u represents the pulse echo number, U represents the number of pulse echoes, and y represents the matched filter number; represents the matched filtering result of the y-th matched filter on the u-th pulse echo, represents the matched filtering result of the y-th matched filter on U pulses;

[0067] Pair Matrix The pulse number dimension is transformed by FFT to obtain , The t-axis corresponds to the distance dimension, and the v-axis corresponds to the speed dimension; by analyzing The t and v values ​​corresponding to the peak are used to convert the distance and speed of the target device.

[0068] The beneficial effects of the present invention are:

[0069] The present invention uses an electromagnetic metasurface to modulate the incident radar chirp signal through phase coding and then reflects it, uses pseudo-random coding + orthogonal coding, and adopts BPSK phase modulation to modulate the reflected signal. The present invention utilizes the good autocorrelation characteristics of pseudo-random codes and the good orthogonality characteristics of orthogonal coding, wherein orthogonal coding is used to encode electromagnetic metasurface targets, and good orthogonality can make it easier to separate target echoes with different codes; pseudo-random codes, due to their good autocorrelation characteristics and encryption characteristics, can enable detection equipment to identify our targets and detect target distances, and can confuse enemy detection equipment.

[0070] The present invention is different from the existing mode of transmitting and receiving integrated radar communication signals at the same time. Instead, the electromagnetic metasurface is used to make the target passively perform phase coding modulation on the incident radar signal. If the detection party knows the modulation mode of the target echo, the target modulation coding information can be decoded, thereby achieving the function of identifying the target. If the modulation mode of the unknown radar echo is not only unable to decode the communication information in the echo, but also makes the normal detection function of the radar invalid, which has a confusing interference effect on the non-cooperative radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 This is one of the flow charts of a detection and identification method based on orthogonal coding and pseudo-random coding in Example 1 of the present invention.

[0072] Figure 2 This is the second flow chart of a detection and identification method based on orthogonal coding and pseudo-random coding in Example 1 of the present invention.

[0073] Figure 3 This is a schematic diagram of a detection and identification system based on orthogonal coding and pseudo-random coding according to Embodiment 2 of the present invention.

[0074] Figure 4 It is a schematic diagram of the matched filtering result of the received signal in Example 1 of the present invention.

[0075] Figure 5 It is a schematic diagram of the coherent accumulation result of the received signal in Example 1 of the present invention. DETAILED DESCRIPTION

[0076] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0077] Example 1

[0078] This embodiment provides a detection and identification method based on orthogonal coding and pseudo-random coding, such as Figure 1 As shown, including:

[0079] Radar signal generation and transmission: The detection device sets the waveform parameters, generates and transmits the Chirp signal to the target device through the radar transmitter;

[0080] Radar signal echo modulation: The target device performs phase coding modulation on the incident Chirp signal through the electromagnetic metasurface, and then reflects the modulated Chirp signal; Phase coding modulation includes BPSK modulation of the Chirp signal through a number of mutually orthogonal codes, and BPSK modulation of the Chirp signal after phase modulation through a number of mutually orthogonal binary code sequences;

[0081] Radar ranging and target identification: The detection device uses the Chirp signal obtained by the same modulation method as the target device as a matched filter to perform matched filtering on the received echo signal; the matched filtering result is normalized and a first threshold is set. The matched filter code corresponding to the peak value higher than the first threshold is the corresponding target device code, and the time domain position corresponding to the peak value indicates the time of receiving the reflected echo of the target device, thereby calculating the target device code and distance;

[0082] Radar speed measurement: Coherent accumulation is achieved by performing Fourier transform on the matched filtering results of different pulse echoes, and the peak value greater than the second threshold is found in the speed domain and the speed of the target device is calculated, thereby realizing radar detection and target recognition.

[0083] like Figure 2 As shown, the detection and identification method of this embodiment can be implemented by the following steps:

[0084] S1. Set waveform parameters to generate a transmitting wave Chirp signal;

[0085] S2. Set the orthogonal coding and pseudo-random coding, and use the BPSK modulation method to mix the orthogonal coded signals and the same pseudo-random coded signals of different target Chirp signal echoes;

[0086] S3. Constructing a conjugate anti-folding signal of the transmitted signal in step S2 as a matched filter, and performing matched filtering on the received echo signal;

[0087] S4. Determine the distance and orthogonal coding information of the target according to the matched filter peak;

[0088] S5. Repeat step S4 using matched filters carrying different orthogonal codes until all matched filters complete filtering;

[0089] S6. Continue to perform matched filtering on the next group of pulse echoes until all pulse echoes have completed matched filtering; perform coherent accumulation on the matched filtering results of different pulse echoes by the same matched filter to calculate the speed information of the target.

[0090] Preferably, step S2 specifically includes the following sub-steps:

[0091] S201. Set N Hadamard coding sequences of length N and orthogonal to each other , where i represents the i-th Hadamard code, n represents the n-th code element of the Hadamard code, , The value is -1 or 1; the Hadamard coding sequence The corresponding baseband signal It is expressed as:

[0092]

[0093] in, G represents the number of sampling points of each code element in the sequence, g Indicates the first g sampling points, represents the sampling time interval, Represents a unit impulse signal.

[0094] S202. Using mutually orthogonal Hadamard code pairs Chirp Signal conduct modulation:

[0095]

[0096]

[0097] in, represents the Hadamard coded phase modulated Chirp signal, Indicates Chirp signal; Represents a rectangular pulse with a width of T, where T is the period. For time; Indicates the carrier frequency; is the linear FM modulation slope, B is the linear FM modulation bandwidth; " represents dot product, Represents an imaginary unit.

[0098] S203. Set the pseudo code sequence of length P , the value is -1 or 1; the pseudo code sequence The corresponding baseband signal Expressed as:

[0099]

[0100] Among them, Q represents the number of sampling points of each code element in the sequence, p Indicates p Code elements, q Indicates the first q sampling points, Represents a unit impulse signal.

[0101] S204. Perform pseudo-random code phase modulation on the orthogonal coded phase modulated Chirp signal using a baseband signal generated by pseudo-random coding:

[0102]

[0103] in, The integrated signal obtained by pseudo-random code phase modulation is used as the echo modulation signal; ” represents the dot product.

[0104] It should be noted that the echo signal of a normal target is , L is the distance to the target, Tao is the echo delay of different targets. The reflected echo signal of the electromagnetic metasurface target is , if there are 10 electromagnetic metasurface targets, the received mixed echo expression is , is the channel noise, which is set as Gaussian white noise in the experiment.

[0105] Preferably, step S4 specifically includes the following sub-steps:

[0106] S401. In order to maximize the output signal-to-noise ratio and better separate the target echoes with different codes, the matched filtering method is used to perform pulse compression and demodulation on the echo signal to construct the echo modulation signal. The conjugate anti-fold signal As a matched filter , and perform matched filtering on the received echo signal:

[0107]

[0108] in, represents the matched filtering result using the y-th matched filter, Indicates mixed echo, represents the y-th matched filter, ” indicates convolution; N represents the number of electromagnetic metasurface targets, represents the echo delay of the i-th target, Represents the autocorrelation function of the echo signal and the transmitted signal; represents Gaussian white noise; when When the matched filtering result is at position The target peak appears at When , the matched filtering result will not have target peaks, thereby screening out the orthogonal coded signal corresponding to the target echo;

[0109] S402. According to the matched filtering result, the peak value is found. The horizontal axis corresponding to the peak value represents the reflection wave time. It can be converted into the distance of the target and the estimated distance value at this time is recorded. And the corresponding matched filter frequency modulation value estimation result The experimental matched filtering results are as follows: Figure 4 As shown, the matched filtering results of different matched filters on the received waves are compared respectively. The peaks of the matched filtering results of matched filter 1, matched filter 2, and matched filter 2 are at different positions, corresponding to different targets.

[0110] Preferably, step S6 specifically includes the following sub-steps:

[0111] The matched filtering results of all pulses based on the same matched filter form a matrix with three dimensions: time, number of pulses and amplitude:

[0112]

[0113] Where u represents the pulse echo number, U represents the number of pulse echoes, and y represents the matched filter number; represents the matched filtering result of the y-th matched filter on the u-th pulse echo, represents the matched filtering result of the y-th matched filter on U pulses;

[0114] Pair Matrix The pulse number dimension is transformed by FFT to obtain , The t-axis corresponds to the distance dimension, and the v-axis corresponds to the speed dimension; by analyzing The t and v values ​​corresponding to the peak are as follows: Figure 5 As shown, the distance and speed of the target device can be calculated.

[0115] Example 2

[0116] like Figure 3 As shown, this embodiment provides a detection and identification system based on orthogonal coding and pseudo-random coding, including:

[0117] The detection device is configured to generate and transmit a Chirp signal to a target device through a radar transmitter; and use the Chirp signal obtained by the same modulation method as the target device as a matched filter to perform matched filtering on the received echo signal; the matched filtering result is normalized, and a first threshold is set, and the matched filter code corresponding to the peak value higher than the first threshold value is the corresponding target device code, and the time domain position corresponding to the peak value indicates the time of receiving the reflected echo of the target device, thereby calculating the target device code and distance; by performing Fourier transform on the matched filtering results of different pulse echoes to achieve coherent accumulation, find the peak value greater than the second threshold value in the speed domain and calculate the speed of the target device, thereby achieving radar detection and target identification;

[0118] The target device is configured to perform phase coding modulation on the incident Chirp signal through the electromagnetic metasurface, and then reflect the modulated Chirp signal; the phase coding modulation includes BPSK modulation of the Chirp signal through a plurality of mutually orthogonal orthogonal codes, and BPSK modulation of the Chirp signal after orthogonal coding phase modulation through pseudo-random coding.

[0119] Preferably, the target device performs BPSK modulation on the Chirp signal through a plurality of mutually orthogonal orthogonal codes, including:

[0120] Set N Hadamard coding sequences of length N and orthogonal to each other , where i represents the i-th Hadamard code, n represents the n-th code element of the Hadamard code, , The value is -1 or 1;

[0121] Hadamard coding sequence The corresponding baseband signal It is expressed as:

[0122]

[0123] in, G represents the number of sampling points of each code element in the sequence, g Indicates the first g sampling points, represents the sampling time interval, represents a unit impulse signal;

[0124] The Chirp signal is BPSK modulated using mutually orthogonal Hadamard codes:

[0125]

[0126]

[0127] in, represents the Hadamard coded phase modulated Chirp signal, Indicates Chirp signal; Represents a rectangular pulse with a width of T, where T is the period. For time; Indicates the carrier frequency; is the linear FM modulation slope, B is the linear FM modulation bandwidth; " represents dot product, Represents an imaginary unit.

[0128] Preferably, the target device performs BPSK modulation on the Chirp signal after orthogonal coding phase modulation through pseudo-random coding, including:

[0129] Set the pseudo code sequence of length P , the value is -1 or 1; the pseudo code sequence The corresponding baseband signal Expressed as:

[0130]

[0131] Among them, Q represents the number of sampling points of each code element in the sequence, p Indicates p Code elements, q Indicates the first q sampling points, Represents a unit impulse signal.

[0132] Use the baseband signal generated by pseudo-random coding to perform pseudo-random code phase modulation on the orthogonal coded phase modulation Chirp signal:

[0133]

[0134] in, The integrated signal obtained by pseudo-random code phase modulation is used as the echo modulation signal; ” represents the dot product.

[0135] Preferably, the detection device uses a Chirp signal obtained by the same modulation mode as the target device as a matched filter to perform matched filtering on the received echo signal, including:

[0136] The matched filtering method is used to compress and demodulate the echo signal to construct the echo modulation signal. The conjugate anti-fold signal As a matched filter , and perform matched filtering on the received echo signal:

[0137]

[0138] in, represents the matched filtering result using the y-th matched filter, Indicates mixed echo, represents the y-th matched filter, ” indicates convolution; N represents the number of electromagnetic metasurface targets, represents the echo delay of the i-th target, Represents the autocorrelation function of the echo signal and the transmitted signal; represents Gaussian white noise; when When the matched filtering result is at position The target peak appears at When , the matched filtering result will not have target peaks, thereby screening out the orthogonal coded signal corresponding to the target echo;

[0139] According to the matched filtering results, find the peak value and record the distance value at this time and the corresponding matched filter orthogonal coding .

[0140] Preferably, the detection device can perform coherent accumulation of matched filtering results of different pulse echoes through the same matched filter to calculate the distance and speed information of the target device, including:

[0141] The matched filtering results of all pulses based on the same matched filter form a matrix with three dimensions: time, number of pulses and amplitude:

[0142]

[0143] Where u represents the pulse echo number, U represents the number of pulse echoes, and y represents the matched filter number; represents the matched filtering result of the y-th matched filter on the u-th pulse echo, represents the matched filtering result of the y-th matched filter on U pulses;

[0144] Pair Matrix The pulse number dimension is transformed by FFT to obtain , The t-axis corresponds to the distance dimension, and the v-axis corresponds to the speed dimension; by analyzing The t and v values ​​corresponding to the peak are used to convert the distance and speed of the target device.

[0145] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity of description, they are expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the order of the actions described, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

Claims

1. A detection and identification method based on orthogonal coding and pseudo-random coding, characterized in that: include: Radar signal generation and transmission: The detection device sets the waveform parameters, generates and transmits the Chirp signal to the target device through the radar transmitter; Radar signal echo modulation: The target device performs phase coding modulation on the incident Chirp signal through the electromagnetic metasurface, and then reflects the modulated Chirp signal; the phase coding modulation includes BPSK modulation of the Chirp signal through a number of mutually orthogonal binary coding sequences, and BPSK modulation of the Chirp signal after orthogonal coding phase modulation through pseudo-random coding; Radar ranging and target identification: The detection device uses the Chirp signal obtained by the same modulation method as the target device as a matched filter to perform matched filtering on the received echo signal; the matched filtering result is normalized and a first threshold is set. The matched filter code corresponding to the peak value higher than the first threshold is the corresponding target device code, and the time domain position corresponding to the peak value indicates the time of receiving the reflected echo of the target device, thereby calculating the target device code and distance; Radar speed measurement: Coherent accumulation is achieved by performing Fourier transform on the matched filtering results of different pulse echoes, and the peak value greater than the second threshold is found in the speed domain and the speed of the target device is calculated, thereby realizing radar detection and target recognition.

2. A detection and identification method based on orthogonal coding and pseudo-random coding according to claim 1, characterized in that: In the radar signal echo modulation, the Chirp signal is BPSK modulated by a plurality of mutually orthogonal binary coding sequences, including: Set N Hadamard coding sequences of length N and orthogonal to each other , where i represents the i-th Hadamard code, n represents the n-th code element of the Hadamard code, , The value is -1 or 1; Hadamard coding sequence The corresponding baseband signal It is expressed as: in, G represents the number of sampling points of each code element in the sequence, g Indicates the first g sampling points, represents the sampling time interval, represents a unit impulse signal; The Chirp signal is BPSK modulated using mutually orthogonal Hadamard codes: in, represents the Hadamard coded phase modulated Chirp signal, Indicates Chirp signal; Represents a rectangular pulse with a width of T, where T is the period. For time; Indicates the carrier frequency; is the linear FM modulation slope, B is the linear FM modulation bandwidth;" " represents dot product, Represents an imaginary unit.

3. A detection and identification method based on orthogonal coding and pseudo-random coding according to claim 2, characterized in that: In the radar signal echo modulation, BPSK modulation is performed on the Chirp signal after orthogonal coding phase modulation by pseudo-random coding, including: Set the pseudo code sequence of length P , the value is -1 or 1; the pseudo code sequence The corresponding baseband signal Expressed as: Among them, Q represents the number of sampling points of each code element in the sequence, p Indicates p Code elements, q Indicates the first q sampling points, represents a unit impulse signal; Use the baseband signal generated by pseudo-random coding to perform pseudo-random code phase modulation on the orthogonal coded phase modulation Chirp signal: in, The integrated signal obtained by pseudo-random code phase modulation is used as the echo modulation signal; ” represents the dot product.

4. The detection and identification method based on orthogonal coding and pseudo-random coding according to claim 3 is characterized in that: The radar ranging and target identification include: The matched filtering method is used to compress and demodulate the echo signal to construct the echo modulation signal. The conjugate anti-fold signal As a matched filter , and perform matched filtering on the received echo signal: in, represents the matched filtering result using the y-th matched filter, Indicates mixed echo, represents the y-th matched filter, " ” indicates convolution; N represents the number of electromagnetic metasurface targets, represents the echo delay of the i-th target, Represents the autocorrelation function of the echo signal and the transmitted signal; represents Gaussian white noise; when When the matched filtering result is at position The target peak appears at When , the matched filtering result will not have target peaks, thereby screening out the orthogonal coded signal corresponding to the target echo; According to the matched filtering results, find the peak value and record the distance value at this time and the corresponding matched filter orthogonal coding .

5. A detection and identification method based on orthogonal coding and pseudo-random coding according to claim 4, characterized in that: The radar ranging and target identification also includes coherently accumulating the matched filtering results of different pulse echoes by the same matched filter to calculate the distance and speed information of the target device: The matched filtering results of all pulses based on the same matched filter form a matrix with three dimensions: time, number of pulses and amplitude: Wherein, u represents the pulse echo number, U represents the number of pulse echoes, and y represents the matched filter number; represents the matched filtering result of the y-th matched filter on the u-th pulse echo, represents the matched filtering result of the y-th matched filter on U pulses; Pair Matrix The pulse number dimension is transformed by FFT to obtain , The t-axis corresponds to the distance dimension, and the v-axis corresponds to the speed dimension; by analyzing The t and v values ​​corresponding to the peak are used to convert the distance and speed of the target device.

6. A detection and identification system based on orthogonal coding and pseudo-random coding, characterized in that: include: The detection device is configured to generate and transmit a Chirp signal to a target device through a radar transmitter; The Chirp signal obtained by the same modulation method as the target device is used as a matched filter to perform matched filtering on the received echo signal; the matched filtering result is normalized, and a first threshold is set. The matched filter code corresponding to the peak value higher than the first threshold value is the corresponding target device code, and the time domain position corresponding to the peak value indicates the time of receiving the reflected echo of the target device, thereby calculating the target device code and distance; coherent accumulation is achieved by performing Fourier transform on the matched filtering results of different pulse echoes, and a peak value greater than the second threshold value is found in the speed domain and the speed of the target device is calculated, thereby realizing radar detection and target recognition; The target device is configured to perform phase coding modulation on the incident Chirp signal through an electromagnetic metasurface, and then reflect the modulated Chirp signal; the phase coding modulation includes BPSK modulation of the Chirp signal through a plurality of mutually orthogonal binary coding sequences, and BPSK modulation of the Chirp signal after orthogonal coding phase modulation through pseudo-random coding.

7. A detection and identification system based on orthogonal coding and pseudo-random coding according to claim 6, characterized in that: The target device performs BPSK modulation on the Chirp signal through a plurality of mutually orthogonal binary coding sequences, including: Set N Hadamard coding sequences of length N and orthogonal to each other , where i represents the i-th Hadamard code, n represents the n-th code element of the Hadamard code, , The value is -1 or 1; Hadamard coding sequence The corresponding baseband signal It is expressed as: in, G represents the number of sampling points of each code element in the sequence, g Indicates the first g sampling points, represents the sampling time interval, represents a unit impulse signal; The Chirp signal is BPSK modulated using mutually orthogonal Hadamard codes: in, represents the Hadamard coded phase modulated Chirp signal, Indicates Chirp signal; Represents a rectangular pulse with a width of T, where T is the period. For time; Indicates the carrier frequency; is the linear FM modulation slope, B is the linear FM modulation bandwidth;" " represents dot product, Represents an imaginary unit.

8. A detection and identification system based on orthogonal coding and pseudo-random coding according to claim 7, characterized in that: The target device performs BPSK modulation on the Chirp signal after orthogonal coding phase modulation through pseudo-random coding, including: Set the pseudo code sequence of length P , the value is -1 or 1; the pseudo code sequence The corresponding baseband signal Expressed as: Among them, Q represents the number of sampling points of each code element in the sequence, p Indicates p Code elements, q Indicates the first q sampling points, represents a unit impulse signal; Use the baseband signal generated by pseudo-random coding to perform pseudo-random code phase modulation on the orthogonal coded phase modulation Chirp signal: in, The integrated signal obtained by pseudo-random code phase modulation is used as the echo modulation signal; ” represents the dot product.

9. A detection and identification system based on orthogonal coding and pseudo-random coding according to claim 8, characterized in that: The detection device uses a Chirp signal obtained by the same modulation mode as the target device as a matched filter to perform matched filtering on the received echo signal, including: The matched filtering method is used to compress and demodulate the echo signal to construct the echo modulation signal. The conjugate anti-fold signal As a matched filter , and perform matched filtering on the received echo signal: in, represents the matched filtering result using the y-th matched filter, Indicates mixed echo, represents the y-th matched filter, " ” indicates convolution; N represents the number of electromagnetic metasurface targets, represents the echo delay of the i-th target, Represents the autocorrelation function of the echo signal and the transmitted signal; represents Gaussian white noise; when When the matched filtering result is at position The target peak appears at When , the matched filtering result will not have target peaks, thereby screening out the orthogonal coded signal corresponding to the target echo; According to the matched filtering results, find the peak value and record the distance value at this time and the corresponding matched filter orthogonal coding .

10. A detection and identification system based on orthogonal coding and pseudo-random coding according to claim 9, characterized in that: The detection device can perform coherent accumulation of matched filtering results of different pulse echoes through the same matched filter to calculate the distance and speed information of the target device, including: The matched filtering results of all pulses based on the same matched filter form a matrix with three dimensions: time, number of pulses and amplitude: Wherein, u represents the pulse echo number, U represents the number of pulse echoes, and y represents the matched filter number; represents the matched filtering result of the y-th matched filter on the u-th pulse echo, represents the matched filtering result of the y-th matched filter on U pulses; Pair Matrix The pulse number dimension is transformed by FFT to obtain , The t-axis corresponds to the distance dimension, and the v-axis corresponds to the speed dimension; by analyzing The t and v values ​​corresponding to the peak are used to convert the distance and speed of the target device.

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