Method and system for generating V-type frequency modulation signal

Abstract

The invention discloses a V-type frequency modulation signal generation method and system, and the method comprises the steps: obtaining a discrete model of a V-type frequency modulation signal, and obtaining a frequency increment and a frequency initial parameter through the first-order difference relation between the frequency and the phase of the discrete signal; taking the frequency increment, the frequency initial parameter and the constant term as positive frequency modulation digital control parameters, constructing a linear increasing sequence based on the frequency increment, obtaining instantaneous frequency values at different moments by sequentially superposing the frequency initial parameter, and superposing the constant term on the instantaneous frequency values at different moments to obtain a phase sequence of the positive frequency modulation slope; negation processing is carried out on the positive frequency modulation digital control parameters, and a phase sequence of a negative frequency modulation slope is obtained through calculation; and according to the sinusoidal waveform, converting the phase sequence into amplitude data, and generating a V-shaped frequency modulation signal. By optimizing parameter configuration logic and simplifying operation, the operation amount of control parameters and the data transmission amount in the signal generation process can be greatly reduced, the calculation efficiency is remarkably improved, and the consumption of calculation resources is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of signal processing, and particularly relates to a V-type frequency modulation signal generation method and system. BACKGROUND

[0002] The V-type frequency modulation signal is proposed as an improved linear frequency modulation pulse signal variant. The V-type frequency modulation signal retains the good detection performance of the linear frequency modulation pulse signal and significantly improves the time-frequency resolution of the signal, which makes the V-type frequency modulation signal exhibit obvious advantages in multi-target resolution and complex environment adaptability.

[0003] At present, the generation method of the V-type frequency modulation signal needs to independently configure the control parameters of two segments of signals respectively, and the control parameters are issued twice to realize the switching control of the starting frequency and the frequency modulation rate of the V-type frequency modulation signal, which leads to a doubled increase in data transmission and an increase in consumption of computing resources. SUMMARY

[0004] In order to solve the problems in the prior art, the technical scheme adopted by the present application is as follows: The present application provides a V-type frequency modulation signal generation method, which comprises the following steps: Obtaining configuration parameters of the V-type frequency modulation signal, and constructing a time-domain expression model of the V-type frequency modulation signal based on the configuration parameters; Discretizing the time-domain expression model to obtain a discrete model of the V-type frequency modulation signal, wherein the discrete model comprises a phase model of a discrete signal, and the phase model of the discrete signal is expressed as the sum of the following three terms: a constant term, a first-order term having a linear relationship with a discrete time, and a second-order term having a quadratic relationship with the discrete time; Converting the phase model of the discrete signal into a frequency calculation model of the discrete signal through a first-order difference relationship between the frequency and the phase of the discrete signal, obtaining a frequency increment and a frequency initial parameter, wherein the frequency increment is twice the coefficient of the second-order term of the phase model, and the frequency initial parameter is the sum of the coefficient of the first-order term and the coefficient of the second-order term of the phase model; Taking the frequency increment, the frequency initial parameter and the constant term as positive frequency modulation digital control parameters of the V-type frequency modulation signal, and obtaining a phase sequence of a positive frequency modulation slope according to the following phase calculation method: constructing a linearly increasing sequence based on the frequency increment, obtaining instantaneous frequency values at different times by sequentially superimposing the frequency initial parameter, superimposing the constant term on the instantaneous frequency values at different times to obtain the phase sequence; Inverting the positive frequency modulation digital control parameters to obtain negative frequency modulation digital control parameters, and obtaining a phase sequence of a negative frequency modulation slope according to the phase calculation method; Converting the phase sequence of the positive frequency modulation slope and the phase sequence of the negative frequency modulation slope into amplitude data according to a sine waveform to generate the V-type frequency modulation signal.

[0005] In summary, the application provides a V-type frequency modulation signal generation method. Based on the time domain expression model of the V-type frequency modulation signal, the positive frequency modulation digital control parameter of the V-type frequency modulation signal is calculated. The phase sequence of the positive frequency modulation slope of the V-type frequency modulation signal is obtained by calculating the instantaneous frequency value at different times. The positive frequency modulation digital control parameter is inverted based on the signal characteristics of the V-type frequency modulation signal to obtain the negative frequency modulation digital control parameter of the V-type frequency modulation signal. The phase sequence of the negative frequency modulation slope of the V-type frequency modulation signal is further calculated to generate the V-type frequency modulation signal. The calculation and data transmission of the parameter configuration are greatly reduced, the calculation efficiency is significantly improved, and the consumption of calculation resources is effectively reduced by optimizing the parameter configuration logic and simplifying the calculation method while improving the generation efficiency of the V-type frequency modulation signal.

[0006] Further, the phase sequence of the positive frequency modulation slope and the phase sequence of the negative frequency modulation slope are calculated in a multi-path parallel processing manner.

[0007] Further, the discretization processing of the time domain expression model includes: setting a system sampling rate, discretizing the time domain expression model according to the system sampling rate, and obtaining a phase model of a discrete signal of the system; using a working clock as a single-path sampling rate, converting the system sampling rate in the phase discrete model of the system according to the single-path sampling rate, and obtaining a phase model of a discrete signal of a single path.

[0008] Further, the phase model of the discrete signal of the single path is represented by the following formula: ;

[0009] In the formula, T represents the pulse width of the V-type frequency modulation signal, m represents the discrete time, B / 2 represents the bandwidth of the V-type frequency modulation signal, u represents the positive and negative frequency modulation slope of the V-type frequency modulation signal, and u=B / T; M represents the number of processing paths, represents the system sampling rate, represents the single-path sampling rate.

[0010] Further, the configuration parameters of the V-type frequency modulation signal include: signal envelope, center frequency of the V-type frequency modulation signal, pulse width of the V-type frequency modulation signal, bandwidth of the V-type frequency modulation signal, initial phase of the V-type frequency modulation signal, and positive and negative frequency modulation slope of the V-type frequency modulation signal.

[0011] Further, the phase model of the discrete signal is converted into a frequency calculation model of the discrete signal by the first-order difference relationship between the frequency and the phase of the discrete signal, which includes: Based on the phase model of the discrete signal, a phase difference between two adjacent time points is calculated to obtain a frequency calculation model of the discrete signal.

[0012] Further, the phase sequence of the positive frequency modulation slope and the phase sequence of the negative frequency modulation slope are converted into amplitude data by a function lookup table, wherein the function lookup table stores a mapping relationship between the phase and the amplitude of the sine waveform in the interval of π / 2, and the corresponding amplitude of different phases in [0, 2π] is output according to the positive and negative mirror symmetry of the sine function during the lookup table.

[0013] In a second aspect, the present application also provides a V-type frequency modulation signal generation system, wherein the generation system is based on an FPGA module, the FPGA module includes a PS end and a PL end, the PS end is configured to perform floating point operations on the frequency increment, the frequency initial parameter and the constant term based on the V-type frequency modulation signal generation method provided by the present application, the PL end is configured to generate the positive frequency modulation digital control parameter and the negative frequency modulation digital control parameter based on the frequency increment, the frequency initial parameter and the constant term generated by the PS end, and generate the phase sequence of the positive frequency modulation slope and the phase sequence of the negative frequency modulation slope through an adder.

[0014] Further, the PS end sends the frequency increment, the frequency initial parameter and the constant term to the PL end through an AXI bus.

[0015] Further, the FPGA module further includes a storage module, the storage module is used to store a function lookup table, and the function lookup table stores a mapping relationship between the phase and the amplitude of the sine waveform in the interval of π / 2. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A step flowchart of the V-type frequency modulation signal generation method provided by an embodiment of the present application is provided. Figure 2 A step flowchart of the step of discretizing the time domain expression model in the V-type frequency modulation signal generation method provided by an embodiment of the present application is provided. Figure 3 A schematic diagram of the calculation by the adder in the V-type frequency modulation signal generation system provided by an embodiment of the present application is provided. Figure 4 A step flowchart of the step of generating the V-type frequency modulation signal based on the FPGA module in the V-type frequency modulation signal generation system provided by an embodiment of the present application is provided. Figure 5 A time-frequency characteristic schematic diagram of the V-type frequency modulation signal generated in the test experiment provided by an embodiment of the present application is provided. Figure 6 A frequency spectrum characteristic schematic diagram of the V-type frequency modulation signal generated in the test experiment provided by an embodiment of the present application is provided. DETAILED DESCRIPTION

[0017] The present application will be described in detail below with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present application. Any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the protection scope of the present application.

[0018] To address the shortcomings of existing technologies, embodiments of this application provide a method for generating a V-mode frequency modulation signal, such as... Figure 1 As shown, the generation method includes the following steps: Step S11: Obtain the configuration parameters of the V-mode frequency modulation signal, and construct a time-domain representation model of the V-mode frequency modulation signal based on the configuration parameters.

[0019] Step S12: Discretize the time-domain representation model to obtain the discrete model of the V-mode frequency modulation signal. The discrete model includes the phase model of the discrete signal. The phase model of the discrete signal is represented by the sum of the following three terms: a constant term, a linear term that has a linear relationship with the discrete time, and a quadratic term that has a quadratic relationship with the discrete time.

[0020] Step S13: By using the first-order difference relationship between the frequency and phase of the discrete signal, the phase model of the discrete signal is converted into the frequency calculation model of the discrete signal to obtain the frequency increment and initial frequency parameters. The frequency increment is twice the coefficient of the quadratic term of the phase model, and the initial frequency parameters are the sum of the coefficients of the first and quadratic terms of the phase model.

[0021] Step S14: Use the frequency increment, initial frequency parameters, and constant term as the positive frequency modulation digital control parameters of the V-type frequency modulation signal, and obtain the phase sequence of the positive frequency modulation slope according to the following phase calculation method: construct a linearly increasing sequence based on the frequency increment, obtain the instantaneous frequency values ​​at different times by sequentially superimposing the initial frequency parameters, and superimpose the constant term on the instantaneous frequency values ​​at different times to obtain the phase sequence.

[0022] Step S15: Invert the positive frequency modulation digital control parameters to obtain the negative frequency modulation digital control parameters, and obtain the phase sequence of the negative frequency modulation slope according to the phase calculation method.

[0023] Step S16: Based on the sine waveform, convert the phase sequence of the positive frequency modulation slope and the phase sequence of the negative frequency modulation slope into amplitude data to generate a V-type frequency modulation signal.

[0024] Specifically, configuration parameters covering the signal characteristics of the V-mode FM signal are obtained. These parameters include: signal envelope, center frequency of the V-mode FM signal, pulse width of the V-mode FM signal, bandwidth of the V-mode FM signal, initial phase of the V-mode FM signal, and positive and negative modulation slopes of the V-mode FM signal. A time-domain representation model of the V-mode FM signal is constructed based on these configuration parameters. This model consists of two parts: the signal envelope, which describes the amplitude variation of the V-mode FM signal; and the phase oscillation component, mathematically expressed as a function containing linear and quadratic terms. In one embodiment, the signal envelope is a rectangular window function. When the V-mode FM signal is within the pulse width, the signal envelope amplitude is constant; when the V-mode FM signal is outside the pulse width, the signal envelope is zero.

[0025] The time-domain representation model can reflect the signal envelope and phase oscillation characteristics of a V-mode frequency modulated signal. In one embodiment, the time-domain representation model of a V-mode frequency modulated signal can be expressed by the following formula: ; In the formula, Indicates the signal envelope, and ; Indicates the center frequency of the V-mode frequency modulation signal. Indicates the pulse width of a V-mode frequency modulation signal. This indicates the bandwidth of the V-mode frequency modulation signal. This indicates the initial phase of the V-mode frequency modulation signal; This represents the positive and negative frequency modulation slopes of a V-mode frequency modulation signal, and .

[0026] The time-domain representation model of the V-mode frequency modulation signal is discretized, transforming the continuous time-domain representation model into a discrete model that can be processed by a digital system. The discrete model of the V-mode frequency modulation signal includes the phase model of the discrete signal, which is the sum of the following three terms: The first term is a constant, representing the initial phase shift of the V-mode frequency modulated signal. This constant remains unchanged throughout the signal generation process and does not change with discrete time. The second term is a linear term that has a linear relationship with discrete time, reflecting the linear phase change trend of the V-mode frequency modulated signal over time. The third term is a quadratic term that has a quadratic relationship with discrete time, proportional to the square of the discrete time. This quadratic term reflects the phase change caused by linear frequency modulation. Based on these three terms, the phase model can completely describe the phase state of the discrete signal at each discrete time point, transforming the continuous phase change law into a discrete phase expression that can be computed by the digital system.

[0027] In one embodiment, the discrete model of the V-mode frequency modulated signal can be expressed by the following formula: ; In the formula, Indicates the signal envelope, and ; This indicates the sampling rate.

[0028] Furthermore, the phase model of a discrete signal can be expressed by the following formula: ; In the formula, , where m represents discrete time and M represents the number of processing paths.

[0029] Removing 2π from the phase model of a discrete signal, based on the lookup table principle, the phase model of a discrete signal can be expressed by the following formula: ; In the formula, T represents the pulse width of the V-mode frequency modulation signal, and B / 2 represents the bandwidth of the V-mode frequency modulation signal. The initial phase of the V-mode frequency modulation signal is represented by ; u represents the positive and negative frequency modulation slope of the V-mode frequency modulation signal, and u = B / T; m represents the discrete time, and M represents the number of processing paths; This indicates the system sampling rate.

[0030] According to the phase model of discrete signals, there is a first-order difference relationship between frequency and phase. In the discrete case, frequency is represented by the difference in phase between adjacent time points. The instantaneous frequency at a certain discrete time point can be obtained by calculating the phase difference between that time point and the previous time point. Based on the first-order difference relationship between frequency and phase, the phase model of discrete signals is converted into a frequency calculation model. In one embodiment, the frequency calculation model can be expressed by the following formula: ; In the formula, Indicates frequency.

[0031] The frequency increment and initial frequency parameters are obtained through a frequency calculation model. The frequency increment is twice the coefficient of the quadratic term in the phase model, reflecting the step size of the frequency's linear change with time. The initial frequency parameters are the sum of the coefficients of the linear and quadratic terms in the phase model, representing the frequency value of the V-mode FM signal at the initial moment. Using the frequency increment and initial frequency parameters, the instantaneous frequency sequence of the V-mode FM signal can be obtained through iterative addition, thereby reducing the consumption of logic operation resources and minimizing computational latency.

[0032] Furthermore, based on the obtained constant term, frequency increment, and initial frequency parameters, these three parameters are determined as the forward frequency modulation digital control parameters for the V-mode frequency modulation signal. These parameters determine the frequency and phase change characteristics of the V-mode frequency modulation signal during the forward frequency modulation phase. Based on the forward frequency modulation digital control parameters, the phase sequence of the forward frequency modulation slope is obtained using the following three-step phase calculation method: Step 1: Construct a linearly increasing sequence based on the frequency increment. The frequency increment reflects the rate of change of frequency over time. By continuously accumulating the frequency increment, a series of frequency change values ​​that increase linearly with discrete time can be obtained. The linearly increasing sequence can reflect the trend of frequency gradually increasing during positive frequency modulation.

[0033] The second step is to sequentially superimpose the initial frequency parameters with the above linearly increasing sequence. The initial frequency parameters serve as the frequency reference at the initial time. The instantaneous frequency value at each discrete time point is obtained by adding the frequency reference value to the cumulative frequency increment value at the corresponding time. Thus, the instantaneous frequency values ​​at different times during the positive frequency modulation stage can be obtained.

[0034] The third step is to superimpose the instantaneous frequency values ​​at different times with the constant term. The constant term serves as phase compensation or phase shift. By accumulating and superimposing the results, the phase sequence of the positive frequency modulation slope is finally obtained.

[0035] After obtaining the phase sequence of the positive frequency modulation slope, the positive frequency modulation digital control parameters are inverted by taking advantage of the characteristic that the V-type frequency modulation signal consists of two segments, positive and negative frequency modulation, with opposite signs of the frequency modulation slopes. This changes the sign of the positive frequency modulation digital control parameters, causing the frequency change trend to change from increasing to decreasing, thus obtaining the negative frequency modulation digital control parameters.

[0036] After obtaining the negative frequency modulation (NFM) digital control parameters, the same phase calculation method used to calculate the phase sequence of the positive frequency modulation (PFM) slope is employed to obtain the phase sequence of the NFM slope. A linearly decreasing sequence is constructed based on the frequency increment of the NFM (the original increasing sequence becomes a decreasing sequence due to parameter inversion). Then, the initial frequency parameters of the NFM are sequentially superimposed with the linearly decreasing sequence to obtain the instantaneous frequency values ​​at different times during the NFM phase. Finally, the instantaneous frequency values ​​at different times are superimposed with a constant term and accumulated to obtain the phase sequence of the NFM slope. This parameter reuse calculation method simplifies the calculation process for both the positive and negative NFM slopes, avoids repetitive parameter configuration and calculations, and ensures the phase continuity between the two NFM signal segments, providing a consistent and continuous phase basis for subsequent waveform synthesis.

[0037] Furthermore, after obtaining the phase sequences of the positive and negative frequency modulation slopes, based on the waveform function table, the amplitude of the sinusoidal signal changes periodically with the phase. Different phase values ​​correspond to amplitude points on the sinusoidal waveform. According to the mapping relationship between phase values ​​and sinusoidal amplitudes, the phase sequence is converted into an amplitude sequence. The phase sequences of the positive and negative frequency modulation slopes are matched in the waveform function table respectively, and converted into amplitude data. The amplitude data of the positive and negative frequency modulation slopes are then concatenated in time sequence and combined with the signal envelope to obtain the amplitude data of the V-mode frequency modulation signal, thereby generating the V-mode frequency modulation signal.

[0038] Based on the above description, the method for generating a V-mode frequency modulation (FM) signal provided in this application embodiment calculates the positive frequency modulation digital control parameters of the FM signal based on the time-domain representation model of the FM signal. By calculating the instantaneous frequency values ​​at different times, the phase sequence of the positive frequency modulation slope of the FM signal is obtained. Based on the signal characteristics of the FM signal, the positive frequency modulation digital control parameters are inverted to obtain the negative frequency modulation digital control parameters of the FM signal. The phase sequence of the negative frequency modulation slope of the FM signal is further calculated to generate the FM signal. This method eliminates the need for secondary calculation and distribution of digital control parameters, significantly reducing the computational and data transmission volume of parameter configuration and greatly improving computational efficiency. Furthermore, by optimizing the parameter configuration logic and simplifying the calculation method, the method effectively improves the signal quality while increasing the efficiency of FM signal generation and reducing hardware resource consumption. It can stably generate FM signals that meet the requirements of high-precision application scenarios such as radar.

[0039] As an optional implementation, in step S11, the configuration parameters of the V-mode frequency modulation signal include: signal envelope, center frequency of the V-mode frequency modulation signal, pulse width of the V-mode frequency modulation signal, bandwidth of the V-mode frequency modulation signal, initial phase of the V-mode frequency modulation signal, and positive and negative frequency modulation slope of the V-mode frequency modulation signal.

[0040] The signal envelope determines the time distribution range of the V-mode frequency modulation signal. In this embodiment, a rectangular window is used for the signal envelope to ensure the stability of the signal within the pulse width. The center frequency determines the position of the V-mode frequency modulation signal in the spectrum, and the pulse width specifies the duration of the V-mode frequency modulation signal. The bandwidth of the V-mode frequency modulation signal reflects the range of signal frequency variation and is used to determine the frequency resolution of the signal. The initial phase of the V-mode frequency modulation signal is used to determine the phase state at the start of the signal. The positive and negative frequency modulation slopes of the V-mode frequency modulation signal determine the trend of the signal frequency increasing linearly and then decreasing linearly, thus completely describing the variation law of the V-mode frequency modulation signal in the time domain.

[0041] As an optional implementation method, such as Figure 2As shown, the discretization of the time-domain representation model in step S12 also includes the following steps: Step S121: Set the system sampling rate, and discretize the time-domain representation model according to the system sampling rate to obtain the phase model of the discrete signal of the system.

[0042] Step S122: Using the working clock as the single-channel sampling rate, the system sampling rate in the system's phase discrete model is converted based on the single-channel sampling rate to obtain the phase model of the single-channel discrete signal.

[0043] Specifically, the system sampling rate is set based on the bandwidth, frequency variation range, and number of processing paths of the V-mode frequency modulated signal. The time-domain representation model is then discretized according to this sampling rate. By extracting discrete time points along the continuous time axis at time intervals set by the system sampling rate, the continuous-time variable is converted into a discrete sequence of sampling times. For the phase component of the time-domain representation model, the corresponding phase values ​​are calculated based on the discrete time points, thus transforming the continuous phase function into a series of discrete phase data points. These phase data points collectively constitute the phase model of the system's discrete signal.

[0044] The single-channel processing path uses the operating clock as the reference clock signal and the operating clock as the single-channel sampling rate to avoid data loss or processing errors caused by clock mismatch. In one embodiment, the single-channel sampling rate can be expressed as: ; In the formula, Indicates the single-channel sampling rate. The system sampling rate is represented by , and M represents the number of processing paths.

[0045] After determining the single-channel sampling rate, the system sampling rate in the system's phase discrete model is converted based on the single-channel sampling rate to obtain the phase model of the single-channel discrete signal. This allows the single-channel processing path to efficiently and accurately calculate and process the phase sequence under the control of the working clock, providing a discretization basis for the subsequent generation of positive and negative frequency modulation slope phase sequences, and providing a unified timing reference for the coordinated operation of each processing path in multi-channel parallel processing. In one embodiment, the phase model of the single-channel discrete signal can be expressed by the following formula: ; In the formula, T represents the pulse width of the V-mode frequency modulation signal, and B / 2 represents the bandwidth of the V-mode frequency modulation signal. The initial phase of the V-mode frequency modulation signal is represented by ; u represents the positive and negative frequency modulation slope of the V-mode frequency modulation signal, and u = B / T; m represents the discrete time, and M represents the number of processing paths; This indicates the system sampling rate.

[0046] Furthermore, the phase model of the discrete signal is merged and simplified by using three new coefficients a, b, and c to replace the quadratic coefficient, the linear coefficient, and the constant term, respectively. Specifically, coefficient a replaces the quadratic coefficient, coefficient b replaces the linear coefficient, and coefficient c replaces the constant term.

[0047] As an optional line-of-sight method, in the initial phase When the phase is zero, the phase model of a single-channel discrete signal can be simplified to: ; In the formula, a is the coefficient of the quadratic term, b is the coefficient of the linear term, c is the constant term, and m represents the discrete time.

[0048] Furthermore, when discrete time When the coefficients a, b, and c are used, they can be expressed by the following formula: ; In the formula, B / 2 represents the bandwidth of the V-mode frequency modulation signal; u represents the positive and negative frequency modulation slope of the V-mode frequency modulation signal, and u=B / T; M represents the number of processing paths.

[0049] When discrete time When the coefficients a, b, and c are used, they can be expressed by the following formula: ; In the formula, B / 2 represents the bandwidth of the V-mode frequency modulation signal; u represents the positive and negative frequency modulation slope of the V-mode frequency modulation signal, and u=B / T; M represents the number of processing paths.

[0050] Based on the formulas expressing coefficients a, b, and c, it can be concluded that in the initial phase... When the value is zero, the value of the quadratic coefficient a is determined by the bandwidth and pulse width. The sign of the quadratic coefficient a determines the direction of the frequency modulation slope. Furthermore, the values ​​of coefficients a, b, and c are opposites of each other between two discrete time periods. The frequency phase change of the V-type frequency modulation signal is configured through coefficients a, b, and c.

[0051] As an optional implementation, in step S13, the phase model of the discrete signal is converted into the frequency calculation model of the discrete signal by the first-order difference relationship between the frequency and phase of the discrete signal. This includes: calculating the phase difference between two adjacent time points based on the phase model of the discrete signal to obtain the frequency calculation model of the discrete signal.

[0052] Specifically, utilizing the relationship between frequency and phase in the discrete domain, frequency, as the rate of change of phase over time, is represented in the discrete case as the phase difference between adjacent time points. The phase model of a discrete signal describes the phase state of the discrete signal at each discrete time point. When calculating the phase difference between two adjacent time points, two consecutive discrete time points are selected, such as the nth time point and the (n-1)th time point, and substituted into the phase model of the discrete signal to obtain the phase values ​​corresponding to these two time points. Based on the phase values ​​of adjacent time points, a difference operation is performed to obtain the phase difference between two adjacent time points. Through phase difference calculation, the original phase model consisting of three terms is transformed into an expression containing only the frequency increment and the initial frequency parameter. This expression is the frequency calculation model of the discrete signal.

[0053] In one embodiment, the frequency calculation model for a discrete signal can be expressed by the following formula: ; In the formula, m represents discrete time.

[0054] The frequency increment and initial frequency parameters are obtained through a frequency calculation model of the discrete signal. Based on the frequency increment, initial frequency parameters, and constant terms, the phase sequences of the positive and negative frequency modulation slopes are calculated. As an optional implementation, in steps S14 and S15, the phase sequences of the positive and negative frequency modulation slopes are calculated using multi-channel parallel processing.

[0055] Specifically, during the calculation process, independent processing paths are set up for the phase sequences with positive and negative frequency modulation slopes, respectively. These processing paths are started simultaneously and run in parallel. One processing path is used to calculate the phase sequence with the positive frequency modulation slope, while the other processing path simultaneously processes the phase sequence with the negative frequency modulation slope. Both processing paths simultaneously receive the corresponding control parameters and then synchronously perform operations such as constructing linearly increasing (or decreasing) sequences, superimposing instantaneous frequencies, and accumulating phases.

[0056] By using multi-channel parallel processing, the overall computation time is significantly reduced, improving the efficiency and real-time performance of signal generation, and also increasing hardware utilization. Furthermore, since the phase sequences of the positive and negative frequency modulation slopes are calculated synchronously, strict time alignment between the two can be ensured, laying the foundation for subsequent conversion into waveform data and synthesis of a complete V-mode frequency modulation signal through a function lookup table, and avoiding the impact of time difference caused by serial processing on the continuity and accuracy of the signal.

[0057] As an optional implementation, in step S16, the phase sequence of the positive frequency modulation slope and the phase sequence of the negative frequency modulation slope are converted into amplitude data through a function lookup table. The function lookup table stores the mapping relationship between the phase and amplitude of the sine waveform in the π / 2 interval. When looking up the table, the corresponding amplitude of different phases in [0, 2π] is output according to the positive and negative mirror symmetry of the sine function.

[0058] Specifically, in step S16, the phase sequence of positive and negative frequency modulation slopes is converted into amplitude data using a function lookup table. Regarding the storage design of the function lookup table, based on the positive and negative mirror symmetry of the sine function, the phase-amplitude mapping relationship of the π / 2 interval (i.e., 1 / 4 of the sine wave's period) is selected for storage. The sine function exhibits strict symmetry within the range [0, 2π]: for example, the waveform in the 0~π / 2 interval is mirror-symmetric to the π / 2~π interval, the waveform in the 0~π / 2 interval is positively and negatively symmetric to the π~3π / 2 interval, and the waveform in the π / 2~π interval is positively and negatively symmetric to the 3π / 2~2π interval. Based on the positive and negative mirror symmetry of the sine function, it is unnecessary to store the mapping data for the entire period. The amplitude of any phase within [0, 2π] can be derived through symmetric logic using the stored information in the π / 2 interval, thereby reducing storage resource consumption to 1 / 4 of that for storing the entire period, significantly reducing resource usage.

[0059] In the specific table lookup and conversion process, accurate amplitude conversion is achieved through "phase quadrant judgment + symmetric logic processing". For each phase value in the input phase sequence, quadrant assignment is determined: based on the numerical range of the phase value, it is assigned to one of the following quadrants: [0, π / 2] (first quadrant), [π / 2, π] (second quadrant), [π, 3π / 2] (third quadrant), or [3π / 2, 2π] (fourth quadrant).

[0060] For the first quadrant, the lookup table is directly addressed using the phase value within the range of 0 to π / 2, and the corresponding amplitude is output. For the second quadrant, utilizing mirror symmetry, the lookup table is addressed in reverse using the relative address corresponding to "π - phase value," and the amplitude is output as symmetrical to that in the first quadrant. For the third quadrant, utilizing positive and negative symmetry, the lookup table is first addressed in positive direction using the relative address corresponding to the phase value within the range of π to 3π / 2, and then the output amplitude is negatively taken. For the fourth quadrant, combining mirror and positive / negative symmetry, the lookup table is addressed in reverse using the relative address corresponding to "2π - phase value," and then the output amplitude is negatively taken. Through the above address processing and sign control, the amplitude corresponding to any phase within [0, 2π] is accurately output from the lookup table storing data in the range of 0 to π / 2, reducing resource consumption and improving processing speed.

[0061] Based on the above description, the method for generating a V-mode frequency modulation (FM) signal provided in this application embodiment calculates the positive frequency modulation digital control parameters of the FM signal based on the time-domain representation model of the FM signal. By calculating the instantaneous frequency values ​​at different times, the phase sequence of the positive frequency modulation slope of the FM signal is obtained. Based on the signal characteristics of the FM signal, the positive frequency modulation digital control parameters are inverted to obtain the negative frequency modulation digital control parameters of the FM signal. The phase sequence of the negative frequency modulation slope of the FM signal is further calculated to generate the FM signal. This method eliminates the need for secondary calculation and distribution of digital control parameters, significantly reducing the computational and data transmission volume of parameter configuration and greatly improving computational efficiency. Furthermore, by optimizing the parameter configuration logic and simplifying the calculation method, the method effectively improves the signal quality while increasing the efficiency of FM signal generation and reducing hardware resource consumption. It can stably generate FM signals that meet the requirements of high-precision application scenarios such as radar.

[0062] Secondly, based on the same inventive concept, this application also provides a V-mode frequency modulation signal generation system. The generation system is based on an FPGA module, which includes a PS terminal and a PL terminal. The PS terminal is configured to perform floating-point operations on frequency increment, initial frequency parameters, and constant terms based on the V-mode frequency modulation signal generation method described above. The PL terminal is configured to generate positive frequency modulation digital control parameters and negative frequency modulation digital control parameters based on the frequency increment, initial frequency parameters, and constant terms generated by the PS terminal, and generate a phase sequence of positive frequency modulation slope and a phase sequence of negative frequency modulation slope through an adder.

[0063] Specifically, the PS (Processing System) and PL (Programmable Logic) achieve efficient data and instruction interaction through a high-speed interconnect channel within the FPGA module. The PS is configured to perform floating-point operations on the frequency increment, initial frequency parameters, and constants of the V-mode frequency modulation signal as described above. The PS receives the V-mode frequency modulation signal configuration parameters (such as signal bandwidth, pulse width, center frequency, etc.) from the host computer and calculates the frequency increment, initial frequency parameters, and constants through floating-point operations based on the preset V-mode signal generation logic. The PS transmits the calculated frequency increment, initial frequency parameters, and constants to the PL. The PL is configured to generate positive frequency modulation digital control parameters based on the above parameters and, based on the characteristic that "the two frequency bands of the V-mode frequency modulation signal are opposites of each other," inverts the positive frequency modulation digital control parameters to obtain negative frequency modulation digital control parameters.

[0064] Based on the positive and negative frequency modulation (FM) digital control parameters, the PL terminal uses an adder to generate a phase sequence with a positive FM slope according to the positive FM digital control parameters: a linearly increasing instantaneous frequency sequence is constructed with frequency increments as steps, and then a continuous positive FM phase sequence is obtained by accumulating the instantaneous frequencies and superimposing a constant term; similarly, a negative FM slope phase sequence is generated according to the same calculation logic based on the negative FM digital control parameters. Furthermore, based on the positive and negative FM slope phase sequences, and according to a sine wave, the positive and negative FM slope phase sequences are converted into amplitude data to generate a V-type frequency modulation (FM) signal.

[0065] Based on the above description, the V-mode frequency modulation signal generation system provided in this application generates a V-mode frequency modulation signal by configuring the PS and PL terminals on the FPGA module respectively. This eliminates the need for secondary calculations and the distribution of digital control parameters, significantly reducing the computational and data transmission volume of parameter configuration and lowering hardware resource consumption.

[0066] As an optional implementation, the PS end sends the frequency increment, initial frequency parameters, and constant terms to the PL end via the AXI bus. By leveraging the high-performance communication advantages of the AXI bus in the heterogeneous architecture of the FPGA, an efficient and reliable hardware foundation is provided for parameter interaction between the PS end and the PL end in the V-mode frequency modulation signal generation system, so as to meet the stringent requirements of real-time and accuracy data transmission in high-precision scenarios such as radar.

[0067] As an optional implementation, the FPGA module also includes a storage module for storing a function lookup table. This function lookup table stores the mapping relationship between the phase and amplitude of a sine wave within the π / 2 interval. The function lookup table is designed based on the positive and negative mirror symmetry of the sine function. It eliminates the need to store the mapping data for the entire cycle; by storing information within the π / 2 interval, the amplitude of any phase within [0, 2π] can be derived through symmetrical logic. This reduces storage resource consumption to 1 / 4 of that required for storing the entire cycle, significantly reducing resource usage.

[0068] As an optional implementation method, such as Figure 3 As shown, the phase output calculated by the adder serves as the input to the DDS (Direct Digital Frequency Synthesis) module. The DDS module calculates the phase and outputs real and imaginary data. Based on the data output from the DDS module, a complete V-mode frequency modulated signal is formed by the modulator. Time-division multiplexing technology is used between the adder and the DDS module, achieving parallel output through interleaved clock access, reducing redundant use of storage resources.

[0069] The FPGA module uses a pulse width timer to determine the frequency modulation switching time. It switches the linear frequency modulation phase when the pulse width is halfway through, thus completing the frequency switching of the V-mode frequency modulation signal. The frequency modulation switching control module uses a pulse width timer to monitor the signal generation time in real time; its timing formula is as follows: ; In the formula, This is the global clock cycle of the FPGA module.

[0070] During the positive frequency modulation phase, a phase sequence with a positive frequency modulation slope is generated by calculation; when t=T / 2 (half of the pulse width) in the pulse width timer, the frequency modulation switching signal is triggered, and the discrete frequency value is changed at the same time, and a phase sequence with a negative frequency modulation slope is generated by calculation.

[0071] Furthermore, in one embodiment, the FPGA module has a built-in 8-channel DAC (Digital Analog Converter). The high synchronization accuracy between the multiple DACs facilitates the generation of high-performance signals with multiple channels and phase coherence, which helps maintain phase continuity and avoids phase jumps caused by transmission delays.

[0072] In practical applications, the steps for generating a V-mode frequency modulation signal based on an FPGA module are as follows: Figure 4 As shown, the number of parallel paths on the FPGA and the DAC frequency are determined based on the required V-mode frequency modulation signal. The host computer configures the required pulse width, frequency increment, center frequency, and other parameters and sends them to the PS terminal. The PS terminal performs floating-point calculations to generate the corresponding parameters. The pulse width counter monitors the timing and triggers the frequency switching signal. The PS sends the parameters, and the PL side performs parallel calculations and gradually adds the frequency and phase through adders. The FPGA module generates the address in the corresponding function lookup table from the parameters after the parallel superposition of each path. After matching the address in the waveform function table, the signal is output and undergoes parallel-to-serial conversion through the DAC to output the V-mode frequency modulation signal.

[0073] To further illustrate the method for generating a V-mode frequency modulation signal provided in this application, experimental tests are conducted below to verify the effectiveness of the method. In the experiment, the clock frequency... The time-frequency characteristics of the generated V-mode frequency modulation signal are as follows: Figure 5 As shown, the spectral characteristics are as follows Figure 6 As shown, the parameters of the V-mode frequency modulated signal are: pulse width T = 5 μs, bandwidth B = 500 MHz. Test results show that the generated V-mode frequency modulated signal has excellent time-frequency focusing characteristics.

[0074] It should be noted that traditional FPGA implementations of V-mode frequency modulation signals typically rely on configuring all parameters (including start frequency, modulation slope, and initial phase) of both the positive and negative frequency modulation signals separately. This requires performing numerous multiplication and squaring operations in real-time within the FPGA to accurately generate the frequency and phase control words. This direct computation approach not only consumes a significant amount of valuable dedicated DSP multiplier resources, but its accompanying complex operational logic and multi-stage pipeline structure also lead to a substantial increase in the use of general-purpose lookup tables (LUTs) and registers, severely limiting the system's scalability in multi-channel scenarios.

[0075] This application innovatively constructs a continuous adder chain. Through ingenious algorithmic restructuring, this architecture transforms complex exponentiation operations into continuous addition operations, thus completely avoiding reliance on multipliers at the hardware level. Test data strongly validates the superior performance of this solution: on an FPGA chip of the same process and scale, the V-type frequency modulation signal generation unit, the core of this application, consumes only 1,627 LUTs. In stark contrast, a functionally equivalent but conventional linear frequency modulation signal generation module using a traditional multiplier structure consumes as many as 3,751 LUTs.

[0076] This comparison shows that, while achieving the same frequency modulation function, this solution reduces logic resource consumption by more than 56%. This order-of-magnitude optimization of resource utilization not only significantly reduces hardware costs and power consumption, but also enhances the integration of subsequent systems and facilitates multi-channel parallel expansion, which is crucial in fields such as radar and communications.

[0077] It is understood that the term "exemplary" as used herein means "as an example, illustration, or description." Any embodiment described as "exemplary" is not necessarily preferred or superior to other embodiments and / or does not exclude features in combination with other embodiments. It should be understood that certain features of this application described in the context of a single embodiment for clarity may also be provided in combination in a single embodiment. Conversely, various features of this application described in the context of a single embodiment for clarity may also be provided individually or in any suitable combination or as part of any other described embodiment of this application.

[0078] In the description of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. The "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Furthermore, "at least one" means one or more, and "multiple" means two or more. The terms "first," "second," etc., do not limit the quantity or order of execution, and "first," "second," etc., do not necessarily imply differences.

[0079] The above-disclosed embodiments are merely preferred embodiments of this application, but are not intended to limit the scope of this application. Those skilled in the art will understand that any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and scope of this application and the appended claims are equivalent substitutions and still fall within the scope of this application.

Claims

1. A method for generating a V-mode frequency modulation signal, characterized in that, The generation method includes the following steps: Obtain the configuration parameters of the V-mode frequency modulation signal, and construct a time-domain representation model of the V-mode frequency modulation signal based on the configuration parameters; The time-domain representation model is discretized to obtain a discrete model of the V-mode frequency modulation signal. The discrete model includes a phase model of the discrete signal, which is expressed as the sum of the following three terms: a constant term, a linear term that has a linear relationship with the discrete time, and a quadratic term that has a quadratic relationship with the discrete time. By using the first-order difference relationship between the frequency and phase of the discrete signal, the phase model of the discrete signal is converted into a frequency calculation model of the discrete signal to obtain the frequency increment and initial frequency parameters. The frequency increment is twice the coefficient of the quadratic term of the phase model, and the initial frequency parameters are the sum of the coefficients of the first and quadratic terms of the phase model. Using the frequency increment, the initial frequency parameter, and the constant term as the positive frequency modulation digital control parameters of the V-type frequency modulation signal, the phase sequence of the positive frequency modulation slope is obtained according to the following phase calculation method: a linearly increasing sequence is constructed based on the frequency increment, the instantaneous frequency values ​​at different times are obtained by sequentially superimposing the initial frequency parameter, and the constant term is superimposed on the instantaneous frequency values ​​at different times to obtain the phase sequence; The positive frequency modulation digital control parameters are inverted to obtain the negative frequency modulation digital control parameters, and the phase sequence of the negative frequency modulation slope is obtained according to the phase calculation method. Based on the sinusoidal waveform, the phase sequence of the positive frequency modulation slope and the phase sequence of the negative frequency modulation slope are converted into amplitude data to generate the V-type frequency modulation signal.

2. The method for generating a V-mode frequency modulation signal according to claim 1, characterized in that, The phase sequence of the positive frequency modulation slope and the phase sequence of the negative frequency modulation slope are calculated using a multi-path parallel processing method.

3. The method for generating a V-mode frequency modulation signal according to claim 2, characterized in that, The discretization process of the time-domain representation model includes: Set the system sampling rate, and discretize the time-domain representation model according to the system sampling rate to obtain the phase model of the discrete signal of the system; Using the operating clock as the single-channel sampling rate, the system sampling rate in the phase discrete model of the system is converted according to the single-channel sampling rate to obtain the phase model of the single-channel discrete signal.

4. The method for generating a V-mode frequency modulation signal according to claim 3, characterized in that, The phase model of the single-channel discrete signal is expressed by the following formula: ； In the formula, T represents the pulse width of the V-mode frequency modulation signal, m represents the discrete time, B / 2 represents the bandwidth of the V-mode frequency modulation signal, u represents the positive and negative frequency modulation slope of the V-mode frequency modulation signal, and u=B / T; M represents the number of processing paths. Indicates the system sampling rate. This indicates the single-channel sampling rate.

5. The method for generating a V-mode frequency modulation signal according to claim 1, characterized in that, The configuration parameters of the V-mode frequency modulation signal include: Signal envelope, center frequency of V-mode FM signal, pulse width of V-mode FM signal, bandwidth of V-mode FM signal, initial phase of V-mode FM signal, positive and negative FM slope of V-mode FM signal.

6. The method for generating a V-mode frequency modulation signal according to claim 1, characterized in that, Converting the phase model of a discrete signal into a frequency calculation model using the first-order difference relationship between its frequency and phase includes: Based on the phase model of the discrete signal, the phase difference between two adjacent time points is calculated to obtain the frequency calculation model of the discrete signal.

7. The method for generating a V-mode frequency modulation signal according to claim 1, characterized in that, The phase sequence of the positive frequency modulation slope and the phase sequence of the negative frequency modulation slope are converted into amplitude data through a function lookup table. The function lookup table stores the mapping relationship between the phase and amplitude of the sine waveform in the π / 2 interval. When looking up the table, the corresponding amplitude of different phases in [0, 2π] is output according to the positive and negative mirror symmetry of the sine function.

8. A system for generating a V-mode frequency modulation signal, characterized in that, The generation system is based on an FPGA module, which includes a PS terminal and a PL terminal. The PS terminal is configured to perform floating-point operations on the frequency increment, the initial frequency parameter, and the constant term based on the V-type frequency modulation signal generation method according to any one of claims 1 to 4. The PL terminal is configured to generate positive frequency modulation digital control parameters and negative frequency modulation digital control parameters based on the frequency increment, initial frequency parameter, and constant term generated by the PS terminal, and generate a phase sequence of positive frequency modulation slope and a phase sequence of negative frequency modulation slope through an adder.

9. The V-mode frequency modulation signal generation system according to claim 8, characterized in that, The PS terminal sends the frequency increment, the initial frequency parameters, and the constant terms to the PL terminal via the AXI bus.

10. The V-mode frequency modulation signal generation system according to claim 8, characterized in that, The FPGA module also includes a storage module for storing a function lookup table, which stores the mapping relationship between the phase and amplitude of a sine wave in the π / 2 interval.

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