A detection and communication integrated signal processing method based on positive and negative frequency modulation

Abstract

The embodiment of the present invention discloses a detection and communication integrated signal processing method based on positive and negative frequency modulation, including: a radar system generates an integrated detection and communication waveform, the communication code element information is distributed to each transmission channel after serial-to-parallel conversion, and is mapped to the radar LFM waveform transmitted by each antenna, and the positive or negative frequency modulation slope of the generated LFM signal is determined by the value of the communication code element information; after each receiving channel of the radar system receives the target reflection echo, it is mixed with the corresponding transmitting array element carrier frequency difference and then subjected to bandpass filtering to separate the transmission signal of each channel, and the transmission signal of each channel is processed by communication signal processing and radar signal processing respectively to obtain a serial communication sequence of the communication transmitting end and the result of target detection. The technical solution provided by the embodiment of the present invention solves the problem that the existing integrated waveform solution is difficult to combine the performance advantages of low computational complexity, high communication transmission rate and spectrum utilization.

Description

Technical Field

[0001] The present invention relates to, but is not limited to, the fields of radar technology and wireless communication technology, and in particular to a detection and communication integrated signal processing method based on positive and negative frequency modulation. Background Art

[0002] Integrated detection and communication waveform design is a key technology for achieving this integration. In traditional application platforms, the radar and communication functions of an integrated system are often completely independent. The current trend toward miniaturization and intelligence in various mobile devices requires integrating radar and communication functions into the same waveform, transmission, and processing equipment. This improves system spectrum utilization and reduces device size, cost, and energy consumption.

[0003] Currently, implementations of integrated detection and communication waveforms for MIMO-OFDM radar systems, which combine multiple input multiple output (MIMO) and orthogonal frequency division multiplexing (OFDM), and linear frequency modulation (LFM) signals, often suffer from low real-time performance, high computational complexity, reduced spectrum utilization, or difficulty effectively utilizing the multiple channels of the radar array, reducing communication transmission rates. Summary of the Invention

[0004] Purpose of the present invention: The embodiment of the present invention provides a detection and communication integrated signal processing method based on positive and negative frequency modulation to solve the problem that it is difficult to have the performance advantages of low computational complexity, high communication transmission rate and spectrum utilization in the integrated waveform scheme of existing radar detection signals and communication signals.

[0005] The technical solution of the present invention: An embodiment of the present invention provides a detection and communication integrated signal processing method based on positive and negative frequency modulation, comprising: step 1, a MIMO-OFDM radar system generates a detection and communication integrated waveform of a radar detection signal and a communication signal, including: after serial-to-parallel conversion, communication code element information is distributed to each transmission channel of the MIMO-OFDM radar system and mapped into the radar LFM waveform transmitted by each antenna, and the positive or negative frequency modulation slope of the generated LFM signal is determined by the value of the communication code element information;

[0006] Step 2: After each receiving channel of the MIMO-OFDM radar system receives the target reflected echo, it is mixed with the carrier frequency difference of the corresponding transmitting array element and then subjected to bandpass filtering to separate the transmit signal of each channel. Communication signal processing and radar signal processing are performed on the transmit signal of each channel to obtain a serial communication sequence of the communication transmitting end and the target detection result.

[0007] Optionally, in the above-mentioned detection communication integrated signal processing method based on positive and negative frequency modulation, in step 1,

[0008] When the communication symbol information is "1", the frequency modulation slope of the generated LFM signal is positive;

[0009] When the communication symbol information is "0", the frequency modulation slope of the generated LFM signal is negative.

[0010] Optionally, in the above-mentioned integrated detection communication signal processing method based on positive and negative frequency modulation, step 1 includes:

[0011] Step 11, converting the M serial communication code elements in the communication sequence into a parallel code element sequence {I(m)} by serial-to-parallel conversion, where m is a positive integer from 0 to M-1;

[0012] Step 12: Map each symbol in the parallel symbol sequence {I(m)} to the frequency modulation slope of each transmit channel of the MIMO-OFDM radar system to form a detection and communication integrated baseband signal for each array element;

[0013] Step 13: The MIMO-OFDM radar system performs carrier modulation of the corresponding spectrum on the integrated baseband signal of each array element to form an integrated detection and communication signal of each array element;

[0014] Step 14: Adjust the antenna beam of the MIMO-OFDM radar system according to the communication receiver angle of the communication target so that after the communication target receives the integrated detection and communication signals of each array element, the integrated detection and communication signals transmitted by each transmission channel are spatially beamformed.

[0015] Optionally, in the above-mentioned detection communication integrated signal processing method based on positive and negative frequency modulation,

[0016] In step 12, when I(m)=1, the frequency modulation slope μ of the signal transmitted by the mth array element is m =μ; when I(m)=0, μ m = -μ, in step 12, the integrated baseband signal of the mth array element is:

[0017]

[0018] Where μ = B / T p Indicates the LFM signal slope, B and T p They represent the bandwidth and time width of the LFM signal respectively.

[0019] Optionally, in the above-mentioned detection communication integrated signal processing method based on positive and negative frequency modulation,

[0020] In step 13, the carrier frequency of the mth array element is f m =(m-1)Δf=(m-1)B, the detection and communication integrated signal of the mth array element is;

[0021]

[0022] The vector representation of the detection and communication integrated signal transmitted by the MIMO-OFDM radar system is:

[0023] s(t)=[s1(t),s2(t),…,s M (t)] T .

[0024] Optionally, in the above-mentioned integrated detection and communication signal processing method based on positive and negative frequency modulation, step 2 includes:

[0025] Step 21: The MIMO-OFDM radar system receives the echo signal of the communication target and uses the carrier frequency f of each transmission channel to m Perform mixing processing,

[0026] Step 22: Using a bandpass filter corresponding to each transmission channel to filter the mixed signal, separate the separated signal corresponding to each transmission channel, wherein the separated signal is the detection and communication integrated signal transmitted by the corresponding transmission channel and processed by the target side;

[0027] Step 23, performing communication signal processing and radar signal processing on the separated signals respectively, restoring the serial communication sequence of the communication transmitting end through the communication signal processing, and completing the detection of the target and the extraction of the target information through the radar signal processing.

[0028] Optionally, in the above-mentioned integrated detection and communication signal processing method based on positive and negative frequency modulation, the echo signal of the communication target is a signal obtained by delaying and Doppler frequency modulating the signal S(t) after spatial beamforming, that is:

[0029]

[0030] Among them, f dc is the Doppler frequency of the communication target, τ c is the time delay of the communication target echo;

[0031] The separated signals corresponding to each transmission channel separated in step 22 are: the detection communication integrated signal transmitted by each transmission channel in the transmission processing stage, the superposition delay and Doppler frequency, that is:

[0032]

[0033] Optionally, in the above-mentioned detection communication integrated signal processing method based on positive and negative frequency modulation,

[0034] The communication signal processing performed in step 23 includes:

[0035] Step a1: Use the positive FM signal corresponding to the communication code element information "1" and the negative FM signal corresponding to the communication code element information "0" as matched filter factors to filter the separated signal x m (t) Perform pulse compression to obtain m pairs of pulse compression signals y m1 (t) and y m2 (t);

[0036] Step a2: Process the m pairs of pulse pressure signals y by envelope detection. m1 (t) and y m2 (t) Perform a modulo operation to obtain m pairs of tachycardia data sets |y m1 (t)| and|y m2 (t)|;

[0037] Step a3, through sampling decision processing, each pair of tonogram data set |y m1 (t)| and|y m2 (t)|, and determine the communication symbol corresponding to each pair of tonogram data groups in the receiving channel as:

[0038]

[0039] Step a4, performing parallel-to-serial conversion on the communication symbols demodulated by each receiving channel to obtain serial output data, and restoring the serial communication sequence of the communication transmitting end.

[0040] Optionally, in the above-mentioned detection communication integrated signal processing method based on positive and negative frequency modulation,

[0041] The radar signal processing performed in step 23 includes:

[0042] Step b1: Use the corresponding positive frequency modulation signal or negative frequency modulation signal to separate the separated signal x from the channel. m (t) Perform matched filtering processing, the specific processing method is as follows:

[0043]

[0044] Among them, f dr is the Doppler frequency of the far-field target, τ r is the time delay of radar target echo;

[0045] Step b2: Based on the Doppler frequency matching scheme, perform channel sorting on the matched filtering results of all receiving channels to obtain a channel sorting space H;

[0046] Step b3, performing receiving synthesis processing on the result after channel sorting, and obtaining the received synthesis signal:

[0047]

[0048] Step b4: Perform moving target indication (MTI) and coherent accumulation processing on the received composite signal to complete target detection and target information extraction.

[0049] Optionally, in the above-mentioned integrated detection and communication signal processing method based on positive and negative frequency modulation, step b2 includes:

[0050] Assume that the channel spaces corresponding to the communication code element information "0" and "1" in the transmitted parallel communication sequence {I(m)} are H0 and H1 respectively;

[0051] During the channel sorting process, based on the sizes of the two spaces, the space with more elements is selected as the channel space:

[0052]

[0053] Beneficial effects of the present invention: The embodiment of the present invention provides a detection and communication integrated signal processing method based on positive and negative frequency modulation. In the transmitting stage, by mapping the communication code element information to the frequency modulation slope of the linear frequency modulation signal (i.e., LFM signal) transmitted by the MIMO-OFDM radar array element, the transmitted radar detection signal contains communication information, thereby improving the coupling between the radar signal and the communication signal, and completing the integration of the radar function and the communication function in the waveform design direction; in the receiving stage, the separated signals in each channel obtained after separation are respectively subjected to communication reception processing and radar signal processing, and the serial communication sequence of the communication transmitting end is restored through the communication signal processing, and the detection of the target and the extraction of the target information are completed through radar signal processing. The above-mentioned integrated waveform implementation scheme provided by the embodiment of the present invention mainly includes the following beneficial effects:

[0054] (1) In the technical solution provided by the embodiment of the present invention, based on the formation of an integrated detection and communication waveform, communication code element information is mapped to the frequency modulation slope of the LFM signal, thereby completing the detection of radar targets and the transmission of communication information. Compared with the detection and communication integrated waveform design method that maps binary communication code element information to linear frequency modulation signals with different initial frequencies, the method of generating an integrated waveform in the technical solution provided by the embodiment of the present invention fully utilizes the multi-channel nature of the array, thereby improving the code element transmission rate;

[0055] (2) In the technical solution provided by the embodiment of the present invention, a communication code element demodulation method based on positive and negative frequency modulation is adopted, and the orthogonality between positive and negative frequency modulation signals is utilized to increase the difference in communication code element information judgment and improve the communication bit error rate;

[0056] (3) In the technical solution provided by the embodiment of the present invention, a channel sorting scheme based on Doppler frequency matching is adopted. According to the difference in the target position of the pulse compression result caused by the inconsistency of the code element information in each channel, the channels with the same target position are accumulated to complete the channel sorting process, thereby ensuring the correctness of the target information after channel accumulation and reducing the loss of the SNR of the target after accumulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0058] Figure 1 A schematic diagram of communication symbol information in a method for processing integrated detection and communication signals based on positive and negative frequency modulation provided by an embodiment of the present invention;

[0059] Figure 2 , which is a schematic diagram of the principle of generating and sending a detection communication integrated signal in the transmission processing stage of the detection communication integrated signal processing method based on positive and negative frequency modulation provided by an embodiment of the present invention;

[0060] Figure 3 FIG2 is a schematic diagram showing the principle of the processing process of the receiving processing stage in the integrated signal processing method for detection communication based on positive and negative frequency modulation provided by an embodiment of the present invention;

[0061] Figure 4 A schematic diagram showing simulation results of the integrated detection and communication signal processing method based on positive and negative frequency modulation provided in Example 1 of the present invention;

[0062] Figure 5 This is a schematic diagram of the application processing results of the integrated detection communication signal processing method based on positive and negative frequency modulation provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0063] To make the purpose, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other in any manner.

[0064] As explained in the background technology above, existing solutions for integrated detection and communication waveforms struggle to achieve optimal performance characteristics, including real-time performance, computational complexity, spectrum utilization, and communication transmission rate. Several existing solutions are described below:

[0065] (1) The first integrated waveform solution is to complete the radar function and communication function of the integrated system separately in the airspace. When receiving, the system needs to set zero in the communication direction and radar direction respectively to obtain the radar signal and communication reception signal. However, this method has low real-time performance, high computational complexity, and requires pre-estimation of the radar target direction;

[0066] (2) The second integrated waveform solution is to modulate the radar waveform and the communication waveform into different carrier channels of the multi-carrier system respectively. The two functional waveforms are orthogonal to each other. However, this method requires setting a guard interval to ensure that the communication signal and the detection signal after filtering are independent of each other and do not interfere with each other, which undoubtedly reduces the spectrum utilization rate.

[0067] (3) The third integrated waveform scheme is to divide the antenna system elements into two groups of odd and even, and embed the binary information of the communication into the radar signal. Each pair of elements transmits 1 bit of information, and the binary information modulated by the elements is adjusted by controlling the corresponding time width and bandwidth. This method has good frequency utilization and can ensure that the signal bandwidth and the target distance resolution are not affected by the signal processing method of time domain synthesis bandwidth. However, this method uses two elements to transmit one code element information, fails to effectively utilize the array multi-channel, and reduces the communication transmission rate.

[0068] Given the respective advantages and disadvantages of the various existing integrated detection and communication waveform solutions, it is clearly difficult to combine the performance advantages of low computational complexity, high communication transmission rate, and spectrum utilization. Therefore, how to effectively utilize the multi-channel radar array to achieve integrated detection and communication has become one of the main issues in integrated waveform design technology. To address this issue, an embodiment of the present invention provides a detection and communication integrated signal processing method based on positive and negative frequency modulation. This method is related to related equipment in aerospace systems that require simultaneous radar detection and wireless communication. It is a detection and communication integrated waveform implementation solution that combines multiple-input multiple-output (MIMO) and linear frequency modulation (LFM) systems.

[0069] The present invention provides the following specific embodiments that can be combined with each other. The same or similar concepts or processes may not be described in detail in some embodiments.

[0070] The integrated detection and communication signal processing method based on positive and negative frequency modulation provided by the embodiment of the present invention maps the communication code element information to the frequency modulation slope of the linear frequency modulation signal (i.e., LFM signal) transmitted by the MIMO-OFDM radar array element, so that the transmitted radar detection signal contains communication information, thereby improving the coupling between the radar signal and the communication signal, and completing the integration of radar function and communication function in the direction of waveform design. The integrated detection and communication signal processing method based on positive and negative frequency modulation provided by the embodiment of the present invention mainly includes the following steps:

[0071] Step 1: The MIMO-OFDM radar system generates an integrated detection and communication waveform for radar detection signals and communication signals, including: communication code element information is distributed to each transmission channel of the MIMO-OFDM radar system after serial-to-parallel conversion, and mapped into the radar LFM waveform transmitted by each antenna. The positive or negative frequency modulation slope of the generated LFM signal is determined by the value of the communication code element information;

[0072] Step 2: After each receiving channel of the MIMO-OFDM radar system receives the target reflected echo, it is mixed with the carrier frequency difference of the corresponding transmitting array element and then subjected to bandpass filtering to separate the transmit signal of each channel. Communication signal processing and radar signal processing are performed on the transmit signal of each channel to obtain a serial communication sequence of the communication transmitting end and the target detection result.

[0073] In the waveform transmission processing stage, the embodiment of the present invention can generate a detection and communication integrated waveform of the radar detection signal and the communication signal based on a predefined detection and communication integrated signal model. In the embodiment of the present invention, the communication code element information can be set to "0" or "1". Figure 1 FIG. 1 is a schematic diagram of communication symbol information in a detection communication integrated signal processing method based on positive and negative frequency modulation provided by an embodiment of the present invention. Figure 1 The figure shows a time-frequency schematic model of the integrated detection and communication waveform. The communication code element includes multiple transmission code elements, where all the transmission code elements in (a) are "1", that is, the communication code element information is "1", and in (b) only the second transmission code element is changed to "0", that is, the communication code element information is "0".

[0074] based on Figure 1 (a) and Figure 1For each transmit symbol in the communication symbol information in (b), in step 1 of this embodiment of the present invention, when the communication symbol information is "1," the frequency modulation slope of the generated LFM signal is positive; when the communication symbol information is "0," the frequency modulation slope of the generated LFM signal is negative. Subsequently, the waveform of each transmit channel is modulated to its corresponding carrier frequency and transmitted through the transmit antenna, completing spatial beamforming at the target location.

[0075] In the detection and communication integrated signal reception and processing phase of the embodiment of the invention, each receiving channel of the MIMO-OFDM radar system receives the target's reflected echo and performs corresponding reception processing. The receiving processor performs signal separation, mixing the signals using the corresponding transmit channel carrier frequency and then passing them through a bandpass filter to separate the separate signals for each receiving channel. After obtaining the separated signals of each channel, two aspects of processing need to be performed in parallel. On the one hand, for communication reception processing, the orthogonality between positive and negative FM signals can be utilized, and the positive FM signal and the negative FM signal can be used as matched filter coefficients respectively to perform matched filtering on the separated signals of each channel. The amplitude difference between the two matched filter signals is utilized. After envelope detection and sampling judgment, the code element information contained in the current channel in the received signal is decoded to restore the communication information. On the other hand, for radar reception processing, the code element information contained in each channel has not changed. The transmitted signal of each channel (that is, the integrated detection and communication signal transmitted by each channel) can be directly used for matched filtering. Combined with the corresponding communication information, a channel sorting method based on Doppler frequency matching is adopted to complete the accumulation and synthesis of the matched filtering results of each channel, thereby improving the signal-to-noise ratio (SNR) of the target in the received signal.

[0076] It should be noted that the receiving channel and the transmitting channel in the MIMO-OFDM radar system used to form and transmit integrated detection and communication signals and process target reflection echoes in the embodiment of the present invention are physically the same channel. They are used as the transmitting channel in the transmitting processing stage and as the receiving channel in the receiving processing stage.

[0077] The embodiment of the present invention provides an integrated signal processing method for detection and communication based on positive and negative frequency modulation. In the transmitting stage, by mapping the communication code element information to the frequency modulation slope of the linear frequency modulation signal (i.e., LFM signal) transmitted by the MIMO-OFDM radar array element, the transmitted radar detection signal contains communication information, thereby improving the coupling between the radar signal and the communication signal, and completing the integration of the radar function and the communication function in the waveform design direction; in the receiving stage, the separated signals in each channel obtained after separation are respectively subjected to communication reception processing and radar signal processing, and the serial communication sequence of the communication transmitting end is restored through the communication signal processing, and the detection of the target and the extraction of the target information are completed through radar signal processing. The above-mentioned integrated waveform implementation scheme provided by the embodiment of the present invention mainly includes the following beneficial effects:

[0078] (1) In the technical solution provided by the embodiment of the present invention, based on the formation of an integrated detection and communication waveform, communication code element information is mapped to the frequency modulation slope of the LFM signal, thereby completing the detection of radar targets and the transmission of communication information. Compared with the detection and communication integrated waveform design method that maps binary communication code element information to linear frequency modulation signals with different initial frequencies, the method of generating an integrated waveform in the technical solution provided by the embodiment of the present invention fully utilizes the multi-channel nature of the array, thereby improving the code element transmission rate;

[0079] (2) In the technical solution provided by the embodiment of the present invention, a communication code element demodulation method based on positive and negative frequency modulation is adopted, and the orthogonality between positive and negative frequency modulation signals is utilized to increase the difference in communication code element information judgment and improve the communication bit error rate;

[0080] (3) In the technical solution provided by the embodiment of the present invention, a channel sorting scheme based on Doppler frequency matching is adopted. According to the difference in the target position of the pulse compression result caused by the inconsistency of the code element information in each channel, the channels with the same target position are accumulated to complete the channel sorting process, thereby ensuring the correctness of the target information after channel accumulation and reducing the loss of the SNR of the target after accumulation.

[0081] The integrated detection and communication signal processing method based on positive and negative frequency modulation provided in this embodiment of the present invention primarily includes: processing methods related to the detection and communication integrated signal during the transmission processing stage; and processing methods related to the detection and communication integrated signal during the reception processing stage. The reception processing stage primarily includes three parts: signal separation, communication signal processing, and detection signal processing. The specific processing methods for each of these stages are described in detail below.

[0082] (1) The transmission and processing phase of the integrated detection and communication signal specifically includes the following:

[0083] (1.1), detection and communication integrated signal model

[0084] The detection and communication integrated signal model is used to generate detection and communication integrated waveforms in MIMO-OFDM radar systems, such as Figure 2 1 is a schematic diagram showing the principle of generating and sending a detection communication integrated signal in the transmission processing stage of the detection communication integrated signal processing method based on positive and negative frequency modulation provided by an embodiment of the present invention.

[0085] (1.2) The generation and transmission of the integrated detection and communication signal in the transmission processing stage includes the following processing steps:

[0086] Step 11, converting the M serial communication code elements in the communication sequence into a parallel code element sequence {I(m)} through serial-to-parallel conversion processing, where m is a positive integer from 0 to M-1.

[0087] Step 12: Map each symbol in the parallel symbol sequence {I(m)} to the frequency modulation slope of each transmit channel of the MIMO-OFDM radar system to form a detection and communication integrated baseband signal of each array element.

[0088] In this step, when I(m)=1, the frequency modulation slope μ of the signal transmitted by the mth array element is m =μ; when I(m)=0, μ m = -μ, the detection and communication integrated baseband signal of the mth array element is:

[0089]

[0090] Where μ = B / T p Indicates the LFM signal slope, B and T p They represent the bandwidth and time width of the LFM signal respectively.

[0091] In step 13, the MIMO-OFDM radar system performs carrier modulation of the corresponding spectrum on the integrated baseband signal of each array element to form an integrated detection and communication signal of each array element.

[0092] In this step, carrier modulation of different spectra is performed on the integrated baseband signal of each array element. For example, the carrier frequency for modulating the mth array element is:

[0093] f m =(m-1)Δf=(m-1)B, then the detection and communication integrated signal of the mth array element is;

[0094]

[0095] In addition, the vector representation of the integrated detection and communication signal transmitted by each transmission channel in the MIMO-OFDM radar system can be:

[0096] s(t)=[s0(t),s1(t),…,s M-1 (t)] T .

[0097] Step 14: Adjust the antenna beam of the MIMO-OFDM radar system according to the communication receiver angle of the communication target so that after the communication target receives the integrated detection and communication signals of each array element, the integrated detection and communication signals transmitted by each transmission channel are spatially beamformed to form S(t), which serves as the basis for subsequent formation of the echo signal.

[0098] (2) The receiving and processing stage of the integrated detection and communication signal specifically includes the following:

[0099] Figure 3 The figure shows a schematic diagram of the principle of the processing process of the receiving processing stage in the integrated detection communication signal processing method based on positive and negative frequency modulation provided by an embodiment of the present invention.

[0100] (2.1), receiving echo signals and performing signal separation;

[0101] like Figure 3 The processing of the middle left part includes the following:

[0102] Step 21: The MIMO-OFDM radar system receives the echo signal of the communication target and uses the carrier frequency f of each transmission channel to m Perform frequency mixing;

[0103] In this step, the received echo signal of the communication target is a signal obtained by delaying and Doppler frequency modulation of the signal S(t) after spatial beamforming, that is:

[0104]

[0105] Among them, f dc is the Doppler frequency of the communication target, τ c is the time delay of the communication target echo.

[0106] Step 22, use the bandpass filter corresponding to each transmission channel to filter the mixed signal to separate and obtain the separated signal corresponding to each transmission channel. The separated signal is the detection and communication integrated signal transmitted by the corresponding transmission channel and obtained by the communication target processing.

[0107] In this step, the separated signals corresponding to each transmission channel are: the detection communication integrated signal transmitted by each transmission channel in the transmission processing stage, the superposition delay and Doppler frequency, specifically:

[0108]

[0109] After the corresponding separated signals are separated in each receiving channel, communication signal processing and radar signal processing can be performed on the separated signals in parallel; Figure 3 The processing content on the right side of the middle is executed in parallel.

[0110] (2.2), Communication Signal Processing

[0111] The communication reception and processing process of the detection communication integrated signal is as follows: Figure 3 As shown in the dotted box above the right part, the main processing steps are as follows:

[0112] Step a1: Use the positive FM signal corresponding to the communication code element information "1" and the negative FM signal corresponding to the communication code element information "0" as matched filter factors to filter the separated signal x m (t) Perform pulse compression to obtain m pairs of pulse compression signals y m1 (t) and y m2 (t).

[0113] When the transmission code element com(m) in the current receiving channel is 1 and 0 respectively, 2m pairs of pulse pressure signals y can be obtained. m1 (t) and y m2 (t), as follows:

[0114]

[0115]

[0116] In this step, the signals entering the positive and negative frequency-modulated pulse pressure after passing through the bandpass filter are m separated signals corresponding to m channels. Each separated signal is processed with positive frequency-modulated pulse pressure and negative frequency-modulated pulse pressure respectively to form m pairs of pulse pressure signals y m1 (t) and y m2 (t), a total of 2m signals.

[0117] When the frequency modulation slope matches, the pulse pressure output signal is When the frequency modulation slope does not match, the pulse compression result is similar to the LFM signal spectrum, which is approximately in the form of a rectangular window within a certain period of time.

[0118] Step a2: Process the m pairs of pulse pressure signals y by envelope detection. m1 (t) and y m2 (t) Perform a modulo operation to obtain m pairs of tachycardia data sets |y m1 (t)| and|y m2 (t)|; The envelope detection processing in this step may be performed using an envelope detector.

[0119] Step a3, through sampling decision processing, each pair of tonogram data set |ym1 (t)| and|y m2 (t)|, and the communication symbol (“0” or “1”) corresponding to each pair of tachycardia data sets in the receiving channel is determined as follows:

[0120]

[0121] Step a4, performing parallel-to-serial conversion on the communication symbols demodulated by each receiving channel to obtain serial output data, and restoring the serial communication sequence of the communication transmitting end.

[0122] (2.3), detection signal processing

[0123] The communication reception and processing process of the detection communication integrated signal is as follows: Figure 3 As shown in the dotted box below the middle right part, the main processing steps are as follows:

[0124] Step b1: Use the corresponding positive frequency modulation signal or negative frequency modulation signal to separate the separated signal x from the channel. m (t) Perform matched filtering processing, the specific processing method is as follows:

[0125]

[0126] Among them, f dr is the Doppler frequency of the far-field target, τ r is the time delay of radar target echo;

[0127] Step b2: Based on the Doppler frequency matching scheme, channel sorting is performed on the matched filtering results of all receiving channels to obtain a channel sorting space H.

[0128] In this step, in the positive and negative frequency modulation pulse pressure results, the positions of the same target are and The time difference between the target position in the two pulse pressure results is 2f dr When the target position differences are different due to different target Doppler frequencies, the receiving channel can adopt different channel sorting schemes to obtain the final channel sorting space H.

[0129] In the channel sorting scheme, the time difference corresponding to the target position difference can be divided into three time difference ranges (0, T s ],(T s ,1 / B] and (1 / B,T r ], thereby executing the corresponding channel sorting scheme within each time difference range, as follows:

[0130] a) When the time difference is between (0,T s ] range, The target position in the two pulse pressure results is less than one sampling interval, and there is no obvious difference in the time domain. The pulse pressure results of all channels can be directly accumulated, and the accumulation gain is basically not lost. At this time, the target speed is

[0131] b) When the time difference is between (T s ,1 / B], The corresponding distance is greater than 1 sampling interval but less than 1 distance resolution, that is, Then, when the pulse pressure results of all channels are accumulated, for the radar system, the target position does not change and is still within a range resolution unit, but there will be a certain loss in the accumulation gain. At this time, the target speed satisfies

[0132] c) When the time difference is between (1 / B,T r ] range, the target position distance difference between the positive and negative FM pulse compression signals is greater than one range resolution, making joint accumulation unsuitable. To minimize the accumulation gain, only the channel signal corresponding to one type of code element information (the portion with the majority of "0" or "1") can be selected for channel synthesis.

[0133] Assume that the channel spaces corresponding to the communication code element information "0" and "1" in the transmitted parallel communication sequence {I(m)} are H0 and H1 respectively, that is:

[0134] m∈{H0|I(m)=0}, m∈{H1|I(m)=1}, m=0,1,...,M-1.

[0135] In the channel sorting process, according to the size of the two spaces, the space with more elements is selected as the channel space, and the channel sorting space H is obtained as follows:

[0136]

[0137] Step b3, performing receiving synthesis processing on the result after channel sorting, and obtaining the received synthesis signal:

[0138]

[0139] Step b4: performing Moving Target Indication (MTI) and coherent accumulation processing on the received composite signal to complete target detection and target information extraction.

[0140] The following uses several specific examples to schematically illustrate the application results of the detection and communication integrated signal processing method based on positive and negative frequency modulation provided by the embodiments of the present invention.

[0141] Example 1

[0142] Figure 4 This is a schematic diagram of the simulation results of the integrated detection and communication signal processing method based on positive and negative frequency modulation provided in Example 1 of the present invention.

[0143] Example 1 provides several sets of MATLAB simulation results using the integrated detection and communication signal processing method based on positive and negative frequency modulation provided by an embodiment of the present invention. Figure 4 The figure shows the pulse compression results when the code element in the current channel remains unchanged and changes during communication demodulation. Figure 4 It can be seen that the maximum amplitude of the pulse compression result when the code element changes is much smaller than the maximum amplitude of the pulse compression result when the code element remains unchanged. This feature provides theoretical and practical support for the sampling decision process of communication decoding.

[0144] Example 2

[0145] Figure 5 This is a schematic diagram of the application processing results of the integrated detection communication signal processing method based on positive and negative frequency modulation provided in Example 2 of the present invention.

[0146] Figure 5 The figure shows the comparison of the communication bit error rate between the technical solution provided by the embodiment of the present invention and the detection communication integrated waveform using two adjacent array elements to modulate one symbol information. Figure 5 As can be seen from the figure, compared to the adjacent element modulation scheme, the technical solution provided by the embodiment of the present invention, namely the solution based on positive and negative slope frequency modulation, achieves a lower bit error rate at the same SNR. For the same bit error rate, the required SNR is reduced by approximately 3dB.

[0147] Although the embodiments disclosed herein are as described above, the contents are merely provided to facilitate understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art may make any modifications and variations in the form and details of the embodiments without departing from the spirit and scope of the present invention. However, the scope of patent protection of the present invention shall remain subject to the scope defined by the appended claims.

Claims

1. A detection communication integrated signal processing method based on positive and negative frequency modulation, characterized in that: include: Step 1: The MIMO-OFDM radar system generates an integrated detection and communication waveform for radar detection signals and communication signals, including: communication code element information is distributed to each transmission channel of the MIMO-OFDM radar system after serial-to-parallel conversion, and mapped into the radar LFM waveform transmitted by each antenna. The positive or negative frequency modulation slope of the generated LFM signal is determined by the value of the communication code element information; Step 2: After receiving the target reflected echo on each receiving channel of the MIMO-OFDM radar system, the received echo is mixed with the carrier frequency difference of the corresponding transmitting array element and then subjected to bandpass filtering to separate the transmit signal of each channel. The transmit signal of each channel is subjected to communication signal processing and radar signal processing respectively to obtain a serial communication sequence of the communication transmitting end and a target detection result; The step 2 includes: Step 21: The MIMO-OFDM radar system receives the echo signal of the communication target and uses the carrier frequency of each transmission channel to f m Perform mixing processing, Step 22: Using a bandpass filter corresponding to each transmission channel to filter the mixed signal, separate the separated signal corresponding to each transmission channel, wherein the separated signal is the detection and communication integrated signal transmitted by the corresponding transmission channel and processed by the target side; Step 23, performing communication signal processing and radar signal processing on the separated signals, respectively, recovering the serial communication sequence of the communication transmitter through the communication signal processing, and completing target detection and target information extraction through radar signal processing; The radar signal processing performed in step 23 includes: Step b1: Use the corresponding positive frequency modulation signal or negative frequency modulation signal to separate the separated signals from the channel x m ( t ) to perform matched filtering processing, the specific processing method is as follows: ； in, f dr is the Doppler frequency of the far-field target, is the time delay of radar target echo; Step b2: Based on the Doppler frequency matching scheme, perform channel sorting on the matched filtering results of all receiving channels to obtain a channel sorting space H; Step b3, performing receiving synthesis processing on the result after channel sorting, and obtaining the received synthesis signal: ； Step b4, performing moving target display and coherent accumulation processing on the received composite signal to complete target detection and target information extraction; The step b2 comprises: Assume that the channel spaces corresponding to the communication code element information "0" and "1" in the transmitted parallel communication sequence {I(m)} are H0 and H1 respectively; During the channel sorting process, based on the sizes of the two spaces, the space with more elements is selected as the channel space: 。 2. The integrated signal processing method for detection and communication based on positive and negative frequency modulation according to claim 1, characterized in that: In the step 1, When the communication symbol information is "1", the frequency modulation slope of the generated LFM signal is positive; When the communication symbol information is "0", the frequency modulation slope of the generated LFM signal is negative.

3. The integrated signal processing method for detection and communication based on positive and negative frequency modulation according to claim 2, characterized in that: The step 1 comprises: Step 11, converting the M serial communication code elements in the communication sequence into a parallel code element sequence {I(m)} by serial-to-parallel conversion, where m is a positive integer from 0 to M-1; Step 12: Map each symbol in the parallel symbol sequence {I(m)} to the frequency modulation slope of each transmit channel of the MIMO-OFDM radar system to form a detection and communication integrated baseband signal for each array element; Step 13: The MIMO-OFDM radar system performs carrier modulation of the corresponding spectrum on the integrated baseband signal of each array element to form an integrated detection and communication signal of each array element; Step 14: Adjust the antenna beam of the MIMO-OFDM radar system according to the communication target and the communication receiver angle, so that after the communication target receives the integrated detection and communication signals of each array element, the integrated detection and communication signals transmitted by each transmission channel are spatially beamformed.

4. The integrated signal processing method for detection and communication based on positive and negative frequency modulation according to claim 3, characterized in that: In step 12, when I(m)=1, m The frequency modulation slope of the signal transmitted by each array element μ m = μ ; When I(m)=0, μ m =- μ In step 12, the first m The integrated baseband signal of each array element is: in, μ=B / T p represents the slope of the LFM signal, B and T p They represent the bandwidth and time width of the LFM signal respectively.

5. The integrated signal processing method for detection and communication based on positive and negative frequency modulation according to claim 4, characterized in that: In the step 13, m The carrier frequency of each array element is , No. m The detection and communication integrated signal of each array element is: The vector representation of the detection and communication integrated signal transmitted by the MIMO-OFDM radar system is: 。 6. The integrated signal processing method for detection and communication based on positive and negative frequency modulation according to claim 5, characterized in that: The echo signal of the communication target is the signal synthesized by the spatial beam S(t) The signal after delay and Doppler frequency modulation is: ； in, f dc is the Doppler frequency of the communication target, is the time delay of the communication target echo; The separated signals corresponding to each transmission channel separated in step 22 are: the detection communication integrated signal transmitted by each transmission channel in the transmission processing stage, the superposition delay and Doppler frequency, that is: 。 7. The integrated signal processing method for detection and communication based on positive and negative frequency modulation according to claim 6, characterized in that: The communication signal processing performed in step 23 includes: Step a1, using the positive FM signal corresponding to the communication code element information "1" and the negative FM signal corresponding to the communication code element information "0" as matched filter factors, the separated signals separated by the channel are x m ( t ) to perform pulse compression and obtain m pairs of pulse pressure signals and ; Step a2: Process m pairs of pulse pressure signals by envelope detection. and Perform the modulo operation to obtain m pairs of pulse pressure modulus data sets and ; Step a3, through sampling decision processing for each pair of pulse pressure model data set and The maximum amplitude is compared to determine the communication symbol corresponding to each pair of pulse compression mode data groups in the receiving channel: ； Step a4, performing parallel-to-serial conversion on the communication symbols demodulated by each receiving channel to obtain serial output data, and restoring the serial communication sequence of the communication transmitting end.

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