Pulse radar multi-waveform signal generation method based on DAC

Abstract

The invention relates to a pulse radar multi-waveform signal generation method based on a DAC (Digital-to-Analog Converter), which belongs to the field of signal processing, can flexibly set each parameter of a signal, adopts an all-digital method to design and generate multiple pulse radar signals in a relatively complex environment scene, realizes the generation of multiple pulse radar signal waveforms in an application environment, and improves the signal processing efficiency. Comprising frequency modulation (conventional frequency modulation, frequency diversity and frequency agility), repetition frequency (PRI) modulation (conventional, stagger, jitter, slip and jump) and intra-pulse modulation (intra-pulse single tone, linear frequency modulation, non-linear frequency modulation, phase encoding, frequency encoding and hybrid encoding), various pulse radar waveforms can be combined at the same time, and dynamic adjustment can be performed according to the bit width of DAC working data. Corresponding signals can be generated through adjustment according to a signal waveform output mode, and the method has obvious advantages in simulation generation of electromagnetic environment pulse radar signals.

Description

Technical Field

[0001] The present invention relates to the field of signal processing, and in particular, to a method for generating multi-waveform signals of a pulsed radar based on a DAC. Background Art

[0002] Currently, the application environment in which radars are located is becoming increasingly complex, and the electromagnetic interference and clutter faced are more diverse, posing higher requirements for radar performance. Radars also need to meet the detection requirements of multiple tasks and the functional requirements of multiple modes, requiring higher flexibility in radar systems. Therefore, generating various pulsed radar signal waveforms using software can adjust radar parameters in real time according to application scenarios and task requirements, improving the anti-interference ability of the radar and increasing the difficulty of reconnaissance and interference by the other party.

[0003] Traditional radars usually have hardware as the core and design the hardware according to actual needs and around actual functions. When changing the radar functions, it is usually necessary to change both the hardware and software, which requires a large amount of manpower and material resources. Obviously, traditional radars with hardware as the core cannot meet the characteristics of high flexibility and openness, and the radar performance will also be greatly restricted by the hardware. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for generating multi-waveform signals of a pulsed radar based on a DAC, which solves the deficiencies existing in the prior art.

[0005] The purpose of the present invention is achieved through the following technical solutions: A method for generating multi-waveform signals of a pulsed radar based on a DAC, the method comprising: Step 1: Set common parameters, frequency modulation type, pulse repetition frequency (PRF) modulation type, and intra-pulse modulation type, determine other PRF parameters according to the set PRF modulation type, and determine other intra-pulse modulation parameters according to the set intra-pulse modulation type; Step 2: Initialize the pulse type and determine whether the set pulsed radar parameters are correct; Step 3: Initialize the frequency type, intra-pulse modulation type, and PRF type respectively; Step 4: Determine the final number of pulses and the PRI value of the pulses, determine the intra-pulse and extra-pulse sampling points of each pulse according to the pulse PRI value and the sampling rate, and generate corresponding intra-pulse baseband data through quadrature modulation according to the intra-pulse modulation type; Step 5: Output the corresponding signal according to the signal output mode, perform corresponding frequency modulation processing on each pulse according to the frequency modulation type, normalize the amplitude of the generated pulsed radar signal according to the set signal power and the number of bits of the DAC chip, and finally store the generated signal data in a data file.

[0006] The setting of common parameters, frequency modulation type, pulse repetition frequency (PRF) modulation type, and intra-pulse modulation type includes: A1. Set common parameters, including sampling rate, number of working data bits of the digital-to-analog converter (DAC), PRI, radar pulse width, and center frequency, where PRI is the radar pulse repetition interval; A2. Set the frequency modulation type, including normal frequency, frequency diversity, and frequency agility. Frequency diversity includes simultaneous diversity and time-division diversity; A3. If the frequency modulation type is simultaneous diversity of frequency diversity, set the number of diversity and the frequency diversity pattern. If the frequency modulation type is time-division diversity of frequency diversity, set the number of diversity and the duration of each frequency. If the frequency modulation type is frequency agility, set the number of agility and the frequency agility pattern; A4. Set the PRF modulation type, including normal PRF, staggered PRF, sliding PRF, jittered PRF, and stepped PRF; A5. Set the intra-pulse modulation type, including single-tone, linear frequency modulation, non-linear frequency modulation, phase coding, frequency coding, and hybrid coding.

[0007] The determination of other PRF parameters according to the set PRF modulation type includes: If the PRF modulation type is sliding PRF, set the minimum value of the sliding PRF, the maximum value of the sliding PRF, and the increment of the sliding PRF; If the PRF modulation type is staggered PRF, set the number of stagger and the stagger sequence; If the PRF modulation type is jittered PRF, set the number of jitters and the amount of PRF jitter.

[0008] The determination of other intra-pulse modulation parameters according to the set intra-pulse modulation type includes: If the intra-pulse modulation type is linear frequency modulation, set the intra-pulse signal bandwidth and the slope type; If the intra-pulse modulation type is non-linear frequency modulation, set the intra-pulse signal bandwidth and the non-linear frequency modulation method, including triangular, sawtooth, sine, tangent, and quadratic function; If the intra-pulse modulation type is phase coding or frequency coding or hybrid coding, set the number of code elements, calculate the corresponding code element width, and set the code element sequence.

[0009] Step 2 includes: Judgment of some parameters of the frequency modulation part: Judge whether the number of frequency diversity is greater than or equal to 2. If so, the parameters are valid. If the frequency diversity is time-division diversity, judge whether the sum of the frequency durations is equal to the pulse width. If so, the parameters are valid, otherwise the parameters are invalid. Judge whether the number of frequency agility is greater than or equal to 0. If so, the parameters are valid, otherwise the parameters are invalid; Judgment of parameters in the pulse repetition frequency (PRF) modulation part: Judge whether the pulse width of the regular PRF or the pulsed PRF is less than or equal to the PRI. If so, the parameter is valid; otherwise, the parameter is invalid. Judge whether the number of pulses of the staggered PRF or the hopping PRF is greater than or equal to 1, and whether the pulse width is less than or equal to the staggered / hopping PRI. If so, the parameter is valid; otherwise, the parameter is invalid. Judge whether the maximum value of the PRI of the sliding PRF is greater than or equal to the minimum value of the sliding PRI, the PRI sliding increment is not 0, and the pulse width is less than or equal to the sliding PRI. If so, the parameter is valid; otherwise, the parameter is invalid. Judge whether the number of PRF jitters is greater than or equal to 3, and whether the jitter amount ranges from [0,1]. If so, the parameter is valid; otherwise, the parameter is invalid. Judgment of parameters in the intra-pulse modulation part: Judge whether the intra-pulse bandwidth of the linear frequency modulation or the non-linear frequency modulation is not 0. If so, the parameter is valid; otherwise, the parameter is invalid. Judge whether the number of codes of the phase coding, frequency coding, or hybrid coding is not 0, and whether the range of the code element sequence is [0, modulation order - 1]. If so, the parameter is valid; otherwise, the parameter is invalid.

[0010] The third step includes: Initialization of the frequency type: When the frequency is regular, initialize the number of frequencies to 1 and the frequency pattern to 0; for frequency diversity or frequency agility, initialize both the number of frequencies and the pattern to the set parameters; if the signal waveform output mode is the DAC mode, calculate the carrier frequency offset of the pulsed radar signal, and if the signal waveform output mode is the DUC mode, the carrier frequency offset. Initialization of the intra-pulse modulation type: For phase coding or frequency coding, if the sequence length and the code element sequence are not provided, randomly generate the code element sequence internally; for hybrid coding, if the sequence length and the content are already provided, directly calculate the corresponding code element sequence, and if not, first randomly generate the code element sequence internally and then calculate the corresponding code element sequence; set the constellation diagram. Initialization of the PRF type: Calculate the number of sampling points of each PRI sequence under the corresponding type according to the staggered PRF, hopping PRF, sliding PRF, and the number of PRF jitters.

[0011] The determination of the final number of pulses and the PRI value of the pulses includes: Calculate the final number of pulses according to the PRF type and the frequency type, that is, the least common multiple of the number of PRIs and the number of frequencies, and determine the PRI value of each pulse.

[0012] The output of the corresponding signal according to the signal output mode includes: When the signal output mode is set to the DUC mode, the output is a baseband signal, generate each pulse in sequence according to the number of pulses, the intra-pulse data is the intra-pulse baseband data, and the extra-pulse data is 0. When the signal output mode is set to the DAC mode, the output is an intermediate frequency signal, which orthogonally up-converts the in-pulse baseband signal, generates each pulse in sequence according to the number of pulses, the in-pulse data is the processed data, and the out-of-pulse data is 0.

[0013] The present invention has the following advantages: A method for generating multi-waveform signals of a pulse radar based on DAC. Using software to generate signals can reuse the same set of hardware resources. According to different functions and modes, different waveform pulse radar signals can be generated by modifying signal parameters. By upgrading the signal library generated by software, the function can be changed or expanded to improve the system performance. It has high flexibility and strong adaptability. When a new pulse radar signal waveform is needed, only the waveform needs to be redeveloped, which can also save a lot of manpower and material resources. Description of the Drawings

[0014] Figure 1 is a schematic flowchart of the present invention; Figure 2 is a schematic diagram of frequency diversity and frequency agility; Figure 3 is a PSK constellation mapping diagram; Figure 4 is a pulse radar spectrogram. Detailed Embodiments

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Usually, the components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application provided in the following drawings is not intended to limit the protection scope of the present application claimed, but only represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present application. The present invention will be further described below in conjunction with the drawings.

[0016] The present invention specifically relates to a method for generating multi-waveform signals of a pulsed radar based on a DAC, which can flexibly set various parameters of the signals. It is designed by a fully digital method to generate pulsed radar signals in various relatively complex environmental scenarios, realizing the generation of various pulsed radar signal waveforms in the application environment, including frequency modulation (conventional frequency modulation, frequency diversity, frequency agility), pulse repetition interval (PRI) modulation (conventional, staggered, jittered, sliding, hopping), intra-pulse modulation (intra-pulse single tone, linear frequency modulation, non-linear frequency modulation, phase coding, frequency coding, hybrid coding). It can simultaneously combine various pulsed radar waveforms, and can be dynamically adjusted according to the working data bit width of the DAC, and can also be adjusted according to the signal waveform output mode to generate corresponding signals, having obvious advantages in the analog generation of pulsed radar signals in the electromagnetic environment.

[0017] As Figure 1 shown, it specifically includes the following contents: (1) Set common parameters, including sampling rate, DAC working data bit number, radar pulse repetition interval (PRI), radar pulse width, center frequency, etc.; (2) Set the frequency modulation type, including conventional frequency, frequency diversity (simultaneous diversity / time-division diversity), and frequency agility. The schematic diagrams of frequency diversity and frequency agility are as Figure 2 shown; (3) According to the set frequency modulation type, determine other frequency parameters: If the frequency modulation type is simultaneous diversity of frequency diversity, set the number of diversities and the frequency diversity pattern; if it is time-division diversity, set the number of diversities and the duration of each frequency, noting that the sum of the durations of each frequency is the pulse width. If the frequency modulation type is frequency agility, set the number of agility and the frequency agility pattern; (4) Set the PRI modulation type, including conventional PRI, staggered PRI, sliding PRI, jittered PRI, hopping PRI; (5) According to the set PRI modulation type, determine other PRI parameters: If the PRI modulation type is sliding PRI, set the minimum value of sliding PRI, the maximum value of sliding PRI, and the increment of sliding PRI; if the PRI modulation type is staggered PRI, set the number of staggerings and the staggered PRI sequence; if the PRI modulation type is jittered PRI, set the number of jitters and the amount of jittered PRI; (6) Set the intra-pulse modulation type, including intra-pulse single tone, linear frequency modulation (positive slope / negative slope), non-linear frequency modulation (sine wave / sawtooth wave / triangle wave / arctangent function / quadratic function), phase coding (BPSK / QPSK / 8PSK / 16PSK), frequency coding (2FSK / 4FSK / 8FSK / 16FSK), hybrid coding (2FSK-2PSK / 4FSK-4PSK / 8FSK-8PSK / 16FSK-16PSK); (7)Set other intra-pulse modulation parameters according to the set intra-pulse modulation type. If the intra-pulse modulation type is linear frequency modulation, set the intra-pulse signal bandwidth and slope type (positive slope / negative slope); if the intra-pulse modulation type is non-linear frequency modulation, set the intra-pulse signal bandwidth and non-linear frequency modulation method, including triangular (up then down / down then up), sawtooth, sine, tangent, quadratic function; if the intra-pulse modulation type is phase coding or frequency coding or hybrid coding, set the number of code elements and calculate the corresponding code element width, set the code element sequence (can be not set, randomly generated internally later), note that the modulation frequency deviation needs to be set for frequency coding. (8)Initialize the pulse radar and judge whether the set pulse radar parameters are correct; specifically including the following: 1. Judgment of frequency modulation part parameters: Frequency diversity: The number of diversity must be ≥2, and the sum of the frequency duration of time-division diversity is equal to the pulse width, otherwise the parameters are invalid; Frequency agility: The number of agility must be ≥0, otherwise the parameters are invalid.

[0018] 2. Judgment of PRF modulation part parameters: PRF conventional or PRF jitter: The pulse width must be ≤PRI, otherwise the parameters are invalid; PRF stagger or PRF hopping: The number of pulses must be ≥1, and the pulse width must be ≤stagger / hopping PRI, otherwise the parameters are invalid; PRF sliding: The maximum value of the sliding PRI must be ≥the minimum value of the sliding PRI, the PRI sliding increment is not equal to 0, and the pulse width must be ≤the sliding PRI, otherwise the parameters are invalid; PRF jitter: The number of jitters ≥3, and the jitter amount value range is [0,1], otherwise the parameters are invalid.

[0019] 3. Judgment of intra-pulse modulation part parameters: Linear frequency modulation or non-linear frequency modulation: The intra-pulse bandwidth is not 0, otherwise the parameters are invalid; Phase / frequency / hybrid coding: The number of codings is not 0, and the code element sequence value range is [0, modulation order - 1], otherwise the parameters are invalid.

[0020] (9)Initialize the frequency type, intra-pulse modulation type, and PRF type respectively; specifically including the following: 1. Frequency type initialization: When the frequency is conventional, the number of frequencies is 1 and the frequency pattern is 0; Frequency diversity or frequency agility: The number of frequencies and the pattern are both the set parameters; If the signal waveform output mode is DAC mode, calculate the carrier frequency offset of the pulse radar signal; if the signal waveform output mode is DUC mode, then the carrier frequency offset.

[0021] 2. Intra-pulse modulation type initialization: Phase encoding or frequency encoding: If the sequence length and symbol sequence are not provided, a symbol sequence is randomly generated internally; Hybrid encoding: If the sequence length and content are provided, the corresponding FSK symbol sequence and PSK symbol sequence are directly calculated; if not, a symbol sequence is first randomly generated internally, and then the corresponding FSK and PSK symbol sequences are calculated; Set the constellation diagram of the corresponding order of PSK: The PSK constellation mapping diagram is as Figure 3 shown, Figure 3 Among them, (a) is the BPSK constellation diagram, (b) is the QSPK constellation diagram, (c) is the 8PSK constellation diagram, and (d) is the 16PSK constellation diagram.

[0022] 3. Pulse repetition frequency type initialization: According to the pulse repetition frequency stagger, pulse repetition frequency hopping, pulse repetition frequency sliding, and the number of pulse repetition frequency jitters, calculate the number of sampling points for each PRI sequence under the corresponding type respectively.

[0023] (10) Determine the final number of pulses and the PRI value of each pulse; Calculate the final number of pulses according to the pulse repetition frequency type and frequency type, that is, the least common multiple of the number of PRIs and the number of frequencies, and determine the PRI value of each pulse; (11) Determine the intra-pulse and extra-pulse sampling points of each pulse according to the pulse PRI value and the sampling rate; (12) Generate the corresponding intra-pulse baseband data through orthogonal modulation according to the intra-pulse modulation type. The specific generation expression is as follows: Intra-pulse single tone: The I channel of the baseband data is 1, and the Q channel is 0; Linear frequency modulation: The most commonly used intra-pulse modulation waveform in pulse compression radar, also called chirp signal, and the mathematical expression is: , Among them, is the time variable, is the signal amplitude of the linear frequency modulation signal at moment, is the carrier frequency, is the frequency modulation slope of the signal, is the amplitude modulation coefficient.

[0024] Nonlinear frequency modulation, the mathematical expression is: , Among them, is the signal amplitude of the nonlinear frequency modulation signal at moment, is the intra-pulse modulation bandwidth, is the sampling frequency, and T is the intra-pulse sampling time interval. are the set different intra-pulse modulation types at moment, which mainly include five modulation types: sine function, trigonometric function, sawtooth function, tangent function, and quadratic function.

[0025] After orthogonal decomposition, we get: , ; The frequency expression of the sine function is: , The frequency expression of the trigonometric function is: , The frequency expression of the sawtooth function is: The frequency expression of the tangent function is: , The frequency expression of the quadratic function is: , Phase encoding: Map the symbol sequence to the constellation diagram according to the mapping relationship such as Figure 3 ; Frequency encoding: , , is the corresponding modulation frequency offset; Hybrid encoding: First, perform frequency encoding modulation on the signal, and then perform phase encoding modulation within each frequency value time.

[0026] (13) When the signal output mode is set to the DUC mode, the output is a baseband signal, and each pulse is generated in sequence according to the number of pulses. The intra-pulse data is the intra-pulse baseband data, and the extra-pulse data is 0; when the signal output mode is set to the DAC mode, the output is an intermediate frequency signal, and the intra-pulse baseband signal is orthogonally up-converted. Substantially, it is to modulate the received and two in-phase and quadrature signals to the carrier respectively, and each pulse is generated in sequence according to the number of pulses. The intra-pulse is the data after modulation of the baseband signal, and the extra-pulse data is 0.

[0027] (14) According to the frequency modulation type, perform corresponding frequency modulation processing on each pulse, and the processing formula is , where is the diversity pattern or the agile pattern.

[0028] (15) Normalize the generated pulsed radar signal according to the set signal power and the number of bits of the DAC chip. Determine the quantization bits after the generation of the analog interference signal according to the working data bit width of the DAC chip, which is dynamically adjustable: for example, when the working data bit width of the used DAC chip is 8 bits, the maximum quantization value of the generated signal data is ; when the working data bit width of the used DAC chip is 16 bits, the maximum quantization value of the generated signal data is , and so on.

[0029] (16) Store the finally generated signal data in a data file.

[0030] The present invention simulates the proposed method for generating pulsed radar signals using the VisualStudio2019 platform, verifies the generated signal file using the MATLAB2021b platform, and finally tests it using a spectrum analyzer. The results prove that the proposed method is feasible. Taking the sampling rate of 2.4G, DUC mode, 16-bit DAC, frequency type of frequency agility, 3 frequency agility numbers, frequency agility patterns of -100M, 0, 100M, PRF type of conventional PRF, and intrapulse modulation type of intrapulse single tone as examples, the generated signal spectrogram is as shown in Figure 4 shown.

[0031] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications, and improvements, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in related fields. And any changes and variations made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A method for generating multi-waveform signals of a pulse radar based on a DAC, characterized in that: The method includes: Step 1: Set common parameters, frequency modulation type, pulse repetition frequency (PRF) modulation type, and intra-pulse modulation type. Determine other PRF parameters according to the set PRF modulation type, and determine other intra-pulse modulation parameters according to the set intra-pulse modulation type; Step 2: Initialize the pulse type and determine whether the set pulse radar parameters are correct; Step 3: Initialize the frequency type, intra-pulse modulation type, and PRF type respectively; Step 4: Determine the final number of pulses and the PRI value of the pulses. Determine the intra-pulse and extra-pulse sampling points for each pulse according to the pulse PRI value and the sampling rate. Generate the corresponding intra-pulse baseband data through orthogonal modulation according to the intra-pulse modulation type; Step 5: Output the corresponding signal according to the signal output mode. Perform corresponding frequency modulation processing on each pulse according to the frequency modulation type. Normalize the amplitude of the generated pulse radar signal according to the set signal power and the number of bits of the DAC chip. Finally, store the generated signal data in a data file.

2. The method for generating multi-waveform signals of a pulse radar based on a DAC according to claim 1, characterized in that: The setting of the common parameters, frequency modulation type, PRF modulation type, and intra-pulse modulation type includes: A1: Set common parameters, including sampling rate, DAC operating data bits, PRI, radar pulse width, and center frequency, where PRI is the radar pulse repetition interval; A2: Set the frequency modulation type, including frequency conventional, frequency diversity, and frequency agility. Frequency diversity includes simultaneous diversity and time-division diversity; A3: If the frequency modulation type is simultaneous diversity of frequency diversity, set the number of diversities and the frequency diversity pattern. If the frequency modulation type is time-division diversity of frequency diversity, set the number of diversities and the duration of each frequency. If the frequency modulation type is frequency agility, set the number of agility and the frequency agility pattern; A4: Set the PRF modulation type, including PRF conventional, PRF stagger, PRF slide, PRF jitter, and PRF hop; A5: Set the intra-pulse modulation type, including intra-pulse single tone, linear frequency modulation, non-linear frequency modulation, phase coding, frequency coding, and hybrid coding.

3. A method for generating multi-waveform signals of a pulse radar based on a DAC according to claim 2, characterized in that: The determination of other PRF parameters according to the set PRF modulation type includes: If the PRF modulation type is PRF slide, set the minimum PRF value of PRF slide, the maximum PRF value of PRF slide, and the PRF increment of PRF slide; If the PRF modulation type is PRF stagger, set the number of PRF staggers and the PRF stagger sequence; If the PRF modulation type is PRF jitter, set the number of jitters and the PRF jitter amount.

4. A method for generating multi-waveform signals of a pulse radar based on a DAC according to claim 2, characterized in that: The determination of other intra-pulse modulation parameters according to the set intra-pulse modulation type includes: If the intra-pulse modulation type is linear frequency modulation, set the intra-pulse signal bandwidth and the slope type; If the intra-pulse modulation type is non-linear frequency modulation, set the intra-pulse signal bandwidth and the non-linear frequency modulation method, including triangle, sawtooth, sine, tangent, and quadratic function; If the intra-pulse modulation type is phase coding or frequency coding or hybrid coding, set the number of code elements and calculate the corresponding code element width, and set the code element sequence.

5. A method for generating multi-waveform signals of a pulse radar based on a DAC according to claim 2, characterized in that: The said Step 2 includes: Parameter judgment of the frequency modulation part: Judge whether the number of frequency diversities is greater than or equal to 2. If so, the parameter is valid. If the frequency diversity is time-division diversity, judge whether the sum of the frequency duration is equal to the pulse width. If so, the parameter is valid; otherwise, the parameter is invalid. Judge whether the number of frequency agility is greater than or equal to 0. If so, the parameter is valid; otherwise, the parameter is invalid. Parameter judgment of the pulse repetition frequency (PRF) modulation part: Judge whether the PRF regular or PRF jitter pulse width is less than or equal to the PRI. If so, the parameter is valid; otherwise, the parameter is invalid. Judge whether the number of PRF stagger or PRF hop pulses is greater than or equal to 1, and whether the pulse width is less than or equal to the stagger / hop PRI. If so, the parameter is valid; otherwise, the parameter is invalid. Judge whether the maximum value of the PRF slide PRI is greater than or equal to the minimum value of the slide PRI, the PRI slide increment is not 0, and the pulse width is less than or equal to the slide PRI. If so, the parameter is valid; otherwise, the parameter is invalid. Judge whether the number of PRF jitters is greater than or equal to 3, and whether the jitter amount value range is in [0,1]. If so, the parameter is valid; otherwise, the parameter is invalid. Parameter judgment of the intra-pulse modulation part: Judge whether the intra-pulse bandwidth of linear frequency modulation or non-linear frequency modulation is not 0. If so, the parameter is valid; otherwise, the parameter is invalid. Judge whether the number of codes of phase coding, frequency coding or hybrid coding is not 0, and whether the value range of the code element sequence is [0, modulation order - 1]. If so, the parameter is valid; otherwise, the parameter is invalid.

6. A method for generating multi-waveform signals of a pulse radar based on a DAC according to claim 2, characterized in that: Step three includes: Frequency type initialization: When the frequency is regular, initialize the number of frequencies to 1 and the frequency pattern to 0. For frequency diversity or frequency agility, initialize both the number of frequencies and the pattern to the set parameters. If the signal waveform output mode is the DAC mode, calculate the carrier frequency offset of the pulsed radar signal. If the signal waveform output mode is the DUC mode, the carrier frequency offset. Intra-pulse modulation type initialization: If the phase coding or frequency coding does not provide the sequence length and the code element sequence, randomly generate the code element sequence internally. If the hybrid coding has provided the sequence length and content, directly calculate the corresponding code element sequence. If not, first randomly generate the code element sequence internally, and then calculate the corresponding code element sequence. Set the constellation diagram. PRF type initialization: According to the number of PRF stagger, PRF hop, PRF slide and PRF jitter, calculate the number of sampling points of each PRI sequence under the corresponding type respectively.

7. A method for generating multi-waveform signals of a pulse radar based on a DAC according to claim 2, characterized in that: The determination of the final number of pulses and the PRI value of the pulses includes: Calculate the final number of pulses according to the PRF type and the frequency type, that is, the least common multiple of the number of PRIs and the number of frequencies, and determine the PRI value of each pulse.

8. A method for generating multi-waveform signals of a pulse radar based on a DAC according to claim 2, characterized in that: The output of the corresponding signal according to the signal output mode includes: When the signal output mode is set to the DUC mode, the output is the baseband signal. Generate each pulse in sequence according to the number of pulses. The intra-pulse data is the intra-pulse baseband data, and the extra-pulse data is 0. When the signal output mode is set to the DAC mode, the output is the intermediate frequency signal. Perform quadrature up-conversion on the intra-pulse baseband signal. Generate each pulse in sequence according to the number of pulses. The intra-pulse data is the processed data, and the extra-pulse data is 0.

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