Multi-waveform sweep frequency signal generation method and device based on DAC (Digital-to-Analog Converter)

Abstract

The invention relates to a multi-waveform frequency sweep signal generation method and device based on a DAC (Digital-to-Analog Converter), belongs to the field of signal processing, and adopts an all-digital method to design and generate interference signals in various relatively complex environment scenes. Noise amplitude modulation, noise frequency modulation, sine wave amplitude modulation, sine wave frequency modulation, square wave amplitude modulation, square wave frequency modulation, triangular wave amplitude modulation, triangular wave frequency modulation, sawtooth wave amplitude modulation, sawtooth wave frequency modulation, noise amplitude modulation frequency sweep, sine wave amplitude modulation frequency sweep, square wave amplitude modulation frequency sweep, triangular wave amplitude modulation frequency sweep, sawtooth wave amplitude modulation frequency sweep and noise frequency modulation frequency sweep in an electromagnetic environment are realized. According to the method, interference signals such as a sine wave frequency modulation frequency sweep signal, a square wave frequency modulation frequency sweep signal, a triangular wave frequency modulation frequency sweep signal, a sawtooth wave frequency modulation frequency sweep signal, a pure carrier frequency sweep signal and a sweep amplitude frequency sweep signal can be obtained, signal output data can be dynamically adjusted according to the bit width of DAC working data, arbitrary sampling rate conversion can be achieved, and the method has obvious advantages in simulation generation of electromagnetic environment interference signals.

Description

Technical Field

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

[0002] Traditional physical electronic equipment with complex structures has poor confidentiality and is difficult to iterate and upgrade, and cannot meet the test and verification requirements of receiving test equipment for various types of interference signals in an increasingly complex electromagnetic environment. Therefore, generating various realistic electromagnetic interference signals by using software has become the mainstream method today. Compared with traditional physical signal sources, it has advantages such as low cost and strong feasibility.

[0003] Currently, in the research and design of semi-physical solutions, most adopt the implementation method of editing signal parameters through upper computer software and controlling the hardware system to generate signals in corresponding forms. The system design has a certain integrity and feasibility, but the types of interference signals designed are relatively single, with poor expandability and insufficient versatility, and it is difficult to complete the simulation of various and complex electromagnetic interference signals in a complex electromagnetic environment, having certain limitations in practical applications. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art, and provides a method and device for generating multi-waveform swept-frequency signals based on a DAC, solving 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 swept-frequency signals based on a DAC, the method comprising: Step 1: Set the common parameters of the swept-frequency signal, the modulation shape of the interference signal, and the type of the interference signal; Step 2: Calculate the sweep time, calculate the total number of sweep points in combination with the sampling rate, and generate corresponding interference signals according to the set type corresponding to the modulation shape of the interference signal; Step 3: Determine whether the generated signal is a pure swept-frequency signal. If so, perform the operation in Step 5, otherwise perform the operation in Step 4; Step 4: Perform AM amplitude modulation or FM frequency modulation on the generated interference signal, and use a filter to change the sampling rate, and sample the original data to the target sampling rate; Step 5: Determine whether the set signal type is the first set signal type or the second set signal type. If it is the first set signal type, perform processing according to the set signal power and the number of bits of the DAC chip, and store the generated signal data. If it is the second set signal type, perform a sweep on the stored signal data.

[0006] The said Step 1 includes: A1. Set the common parameters of the swept signal, including the sampling rate, modulation frequency, center frequency, swept bandwidth swept_bw, swept speed swept_v, modulation depth, and modulation frequency deviation; A2. Set the required modulation shape of the interference signal, including noise, sine wave, square wave, triangular wave, and sawtooth wave; A3. Set the required type of interference signal, including swept CHIRP, amplitude-modulated swept AM_CHIRP, and frequency-modulated swept FM_CHIRP.

[0007] The second step includes: B1. Calculate the swept time as ; B2. Calculate the total number of swept points according to the sampling rate fs and the swept time swept_t; B3. Set the type according to the corresponding modulation shape of the interference signal, and generate the corresponding noise signal, sine wave, square wave, triangular wave, and sawtooth wave signal.

[0008] The fourth step includes: D1. Perform AM amplitude modulation or FM frequency modulation on the generated interference signal, and map it to the space composed of the in-phase and quadrature components of the baseband signal through orthogonal decomposition; D2. Use the Farrow filter for sampling rate conversion to upsample the original data to the target sampling rate.

[0009] The fifth step includes: E1. Remove the filter delay from the sampled baseband signal and store it in a data variable; E2. If the signal type is set to noise amplitude modulation, noise frequency modulation, sine wave amplitude modulation, sine wave frequency modulation, square wave amplitude modulation, square wave frequency modulation, triangular wave amplitude modulation, triangular wave frequency modulation, sawtooth wave amplitude modulation, sawtooth wave frequency modulation, directly execute step E3; If the signal type is set to noise amplitude-modulated sweep, sine wave amplitude-modulated sweep, square wave amplitude-modulated sweep, triangular wave amplitude-modulated sweep, sawtooth wave amplitude-modulated sweep, noise frequency-modulated sweep, sine wave frequency-modulated sweep, square wave frequency-modulated sweep, triangular wave frequency-modulated sweep, sawtooth wave frequency-modulated sweep, pure carrier sweep, amplitude sweep, narrowband sweep signal, perform sweeping on the stored signal data; E3. Determine the quantization bits generated by the analog interference signal according to the set signal power and the number of bits of the DAC chip, and normalize the amplitude of the generated swept signal; E4. Store the generated signal data in a data file.

[0010] A multi - waveform swept - frequency signal generating device based on DAC, the device includes a setting module, a calculation module, a judgment module, a modulation module and a judgment processing module; The setting module: is configured to set the common parameters of the swept - frequency signal, the modulation shape of the interference signal and the type of the interference signal; The calculation module: is configured to calculate the swept - frequency time, calculate the total number of swept - frequency points in combination with the sampling rate, and generate corresponding interference signals according to the set type corresponding to the modulation shape of the interference signal; The judgment module: is configured to judge whether the generated signal is a pure swept - frequency signal. If so, execute the operation of the judgment processing module, otherwise execute the operation of the modulation module; The modulation module: is configured to perform AM amplitude modulation or FM frequency modulation on the generated interference signal, and use a filter to change the sampling rate, and sample the original data to the target sampling rate; The judgment processing module: is configured to judge whether the set signal type is the first set signal type or the second set signal type. If it is the first set signal type, determine the processing according to the set signal power and the number of bits of the DAC chip, and store the generated signal data. If it is the second set signal type, perform swept - frequency on the stored signal data.

[0011] The setting module specifically includes the following: A1. Set the common parameters of the swept - frequency signal, including the sampling rate, modulation frequency, center frequency, swept bandwidth swept_bw, swept speed swept_v, modulation depth and modulation frequency deviation; A2. Set the required modulation shape of the interference signal, including noise, sine wave, square wave, triangular wave and sawtooth wave; A3. Set the required type of the interference signal, including swept - frequency CHIRP, amplitude - modulated swept - frequency AM_CHIRP and frequency - modulated swept - frequency FM_CHIRP.

[0012] The calculation module specifically includes the following: B1. Calculate the swept - frequency time according to the swept bandwidth swept_bw and the swept speed swept_v as ; B2. Calculate the total number of swept - frequency points according to the sampling rate fs and the swept - frequency time swept_t; B3. Generate corresponding noise signals, sine waves, square waves, triangular waves, sawtooth wave signals according to the set type corresponding to the modulation shape of the interference signal.

[0013] The modulation module specifically includes the following: D1. AM amplitude modulation or FM frequency modulation is performed on the generated interference signal, and it is mapped to the space composed of the in-phase and quadrature components of the baseband signal through orthogonal decomposition; D2. The Farrow filter is used for sampling rate conversion to upsample the original data to the target sampling rate.

[0014] The judgment and processing module specifically includes the following: E1. Remove the filter delay of the sampled baseband signal and store it in a data variable; E2. If the set signal types are noise amplitude modulation, noise frequency modulation, sine wave amplitude modulation, sine wave frequency modulation, square wave amplitude modulation, square wave frequency modulation, triangular wave amplitude modulation, triangular wave frequency modulation, sawtooth wave amplitude modulation, sawtooth wave frequency modulation, directly execute step E3; If the set signal types are noise amplitude modulation sweep, sine wave amplitude modulation sweep, square wave amplitude modulation sweep, triangular wave amplitude modulation sweep, sawtooth wave amplitude modulation sweep, noise frequency modulation sweep, sine wave frequency modulation sweep, square wave frequency modulation sweep, triangular wave frequency modulation sweep, sawtooth wave frequency modulation sweep, pure carrier sweep, amplitude sweep, narrowband sweep signal, perform frequency sweep on the stored signal data; E3. Determine the quantization bits generated by the analog interference signal according to the set signal power and the number of bits of the DAC chip, and normalize the amplitude of the generated frequency sweep signal; E4. Store the generated signal data in a data file.

[0015] The present invention has the following advantages: A method and device for generating multi-waveform frequency sweep signals based on DAC can realize 22 interference signal waveforms in the electromagnetic environment, can dynamically adjust the signal output data according to the working data bit width of the DAC, and can also realize arbitrary sampling rate conversion, having obvious advantages in the analog generation of electromagnetic environment interference signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic flow chart of the method of the present invention; Figure 2 It is a schematic structural diagram of the Farrow filter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part rather than all of the embodiments of this application. The components of the embodiments of this application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below in conjunction with the accompanying drawings is not intended to limit the protection scope of the claimed application, but merely represents the selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative efforts belong to the protection scope of this application. The following further describes the present invention in conjunction with the accompanying drawings.

[0018] The present invention specifically relates to a method for generating multi-waveform swept signals based on a DAC, which can flexibly set parameters such as the swept speed of the signal, and uses a fully digital method to design and generate interference signals in various relatively complex environmental scenarios, realizing 22 interference signal waveforms in the electromagnetic environment, including noise amplitude modulation, noise frequency modulation, sine wave amplitude modulation, sine wave frequency modulation, square wave amplitude modulation, square wave frequency modulation, triangular wave amplitude modulation, triangular wave frequency modulation, sawtooth wave amplitude modulation, sawtooth wave frequency modulation, noise amplitude modulation swept, sine wave amplitude modulation swept, square wave amplitude modulation swept, triangular wave amplitude modulation swept, sawtooth wave amplitude modulation swept, noise frequency modulation swept, sine wave frequency modulation swept, square wave frequency modulation swept, triangular wave frequency modulation swept, sawtooth wave frequency modulation swept, pure carrier swept, and swept amplitude swept signals. At the same time, it can dynamically adjust the signal output data according to the working data bit width of the DAC, and can also achieve arbitrary sampling rate conversion, having obvious advantages in the analog generation of electromagnetic environment interference signals.

[0019] As Figure 1 shown, it specifically includes the following content: (1) Set the common parameters of the swept signal, including the sampling rate, modulation frequency, center frequency, swept bandwidth swept_bw, swept speed swept_v, modulation depth (a parameter specific to the amplitude modulation swept type signal), and modulation frequency deviation (a parameter specific to the frequency modulation swept type signal); (2) Set the required modulation shapes of the interference signals, including noise NOISE, sine wave SINE, square wave SQURE, triangular wave TRIANGLE, and sawtooth wave SAWTOOTH; (3) Set the required types of interference signals, including swept CHIRP, amplitude modulation swept AM_CHIRP, and frequency modulation swept FM_CHIRP; (4) Calculate the swept time swept_time according to the swept bandwidth swept_bw and the swept speed swept_v: ; (5) Calculate the total number of swept frequency points according to the sampling time interval f s and the swept frequency time swept_t; (6) Generate a waveform signal m(t) with a corresponding symbol period T according to the modulation shape of the interference signal. It mainly includes five signals: noise signal, sine wave, square wave, triangular wave, and sawtooth wave signal. The generation method is as follows: (a) Noise signal: Generate Gaussian white noise in the full frequency band and generate a noise signal with a specified bandwidth after filtering; (b) The mathematical expression of the sine wave signal is: ; (c) The mathematical expression of the square wave signal is: ; (d) The mathematical expression of the triangular wave signal is: ; (e) The mathematical expression of the sawtooth wave signal is: ; where T is the symbol period and t represents the time variable.

[0020] (7) If it is a simple swept frequency signal, that is, a pure carrier swept frequency or swept amplitude swept frequency signal, through the method of quadrature modulation, the real part is the generated signal and the imaginary part is 0, and then go to step (10); (8) Perform amplitude modulation or frequency modulation on the generated interference signal and map it to the space composed of the in-phase and quadrature components of the baseband signal through orthogonal decomposition; Among them, amplitude modulation (AM) is to make the carrier amplitude change according to the variation law of the modulation signal. The mathematical expression of amplitude modulation can be written as: , In the formula, is the modulation index, and the range is between . If , the envelope of the modulated wave will be severely distorted and the original modulation signal waveform cannot be restored, that is, overmodulation occurs. The interference signal needs to achieve quadrature modulation, and the real part and imaginary part of AM are as follows: , .

[0021] Among them, A is the amplitude modulation coefficient. Frequency modulation (FM) is a modulation method in which the instantaneous frequency of the carrier changes linearly with the modulation signal. The mathematical expression of the frequency modulation signal can be written as: , Expand and simplify to get: , wherein, is the carrier angular frequency, is the modulated noise, sine wave, square wave, triangular wave, sawtooth wave signal, is the modulation angular frequency deviation and phase deviation is given by the following formula: .

[0022] To implement FM, the modulation signal is integrated, and then the sine and cosine are respectively taken from the integrated signal. When implemented by the quadrature modulation method: , ; When implemented in the digital domain, the above formula is digitized: , .

[0023] (9) Arbitrary multiple sampling rate conversion: The Farrow filter structure can overcome the disadvantages of half-band filters, CIC filters, and polyphase filters and can achieve arbitrary multiple sampling rate conversion. During the entire sampling rate conversion process, the coefficients of the filter are fixed, and the coefficients are shown in Table 1. Figure 2 The following shows the structure of the Farrow filter of the present invention. It can be seen from Figure 2 that each output is calculated from 4 inputs. This group of inputs first passes through several sub-filters to obtain , and then and are subjected to a series of multiplication and addition operations to obtain the final output , represents the output of the filter, represents the parameter for adjusting the group delay, Ts represents the sampling interval, and y(k) is the output.

[0024] Table 1. Farrow filter system table wherein, represents the input data of the filter. After passing through the Farrow filter, the original data is sampled rate-converted to the target sampling rate.

[0025] (10) Remove the filter delay from the sampled baseband signal and store it in a data variable; (11) Perform frequency sweeping, i.e., chirp processing, on the stored signal data. The chirp mathematical expression is: , In the formula, is the carrier frequency, is the pulse width, is the frequency modulation slope of the signal, is the in-pulse modulation bandwidth.

[0026] Performing frequency sweeping on the amplitude-modulated or frequency-modulated signal can be expressed as: , When implemented using quadrature modulation, the in-phase branch and the quadrature branch can be respectively expressed as: , , where n represents the time variable after digital discretization, S chirp (n) represents S chirp the discrete signal of

[0027] (12) Normalize the amplitude of the generated pulsed radar signal according to the set signal power and the number of bits of the DAC chip. Determine the quantization number 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.

[0028] (13) Store the finally generated signal data in a data file.

[0029] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms 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 techniques or knowledge in related fields. And the changes and alterations made by those skilled in the art that do not depart from the spirit and scope of the present invention shall all be within the protection scope of the appended claims of the present invention.

Claims

1. A method for generating a multi-waveform swept signal based on a DAC, characterized in that: The method includes: Step 1: Set the common parameters of the swept signal, the modulation shape of the interference signal, and the type of the interference signal; Step 2: Calculate the swept time, calculate the total number of swept points in combination with the sampling rate, and generate a corresponding interference signal according to the set type corresponding to the modulation shape of the interference signal; Step 3: Determine whether the generated signal is a pure swept signal. If so, perform the operation in Step 5, otherwise perform the operation in Step 4; Step 4: Perform AM amplitude modulation or FM frequency modulation on the generated interference signal, and use a filter to change the sampling rate, and sample the original data to the target sampling rate; Step 5: Determine whether the set signal type is the first set signal type or the second set signal type. If it is the first set signal type, perform processing according to the set signal power and the number of bits of the DAC chip, and store the generated signal data. If it is the second set signal type, perform sweeping on the stored signal data.

2. A method for generating a multi-waveform swept signal based on a DAC according to claim 1, characterized in that: The said Step 1 includes: A1: Set the common parameters of the swept signal, including the sampling rate, modulation frequency, center frequency, swept bandwidth swept_bw, swept speed swept_v, modulation depth, and modulation frequency deviation; A2: Set the required modulation shape of the interference signal, including noise, sine wave, square wave, triangular wave, and sawtooth wave; A3: Set the required type of the interference signal, including swept CHIRP, amplitude modulation swept AM_CHIRP, and frequency modulation swept FM_CHIRP.

3. A multi-waveform frequency-sweeping signal generation method based on DAC according to claim 1, characterized in that: The said Step 2 includes: B1. Calculate the swept frequency time according to the swept bandwidth swept_bw and the swept speed swept_v as ; B2: Calculate the total number of swept points according to the sampling rate fs and the swept time swept_t; B3: Generate corresponding noise signals, sine waves, square waves, triangular waves, and sawtooth wave signals according to the set type corresponding to the modulation shape of the interference signal.

4. A method for generating a multi-waveform swept signal based on a DAC according to claim 1, characterized in that: The said Step 4 includes: D1: Perform AM amplitude modulation or FM frequency modulation on the generated interference signal, and map it to the space composed of the in-phase and quadrature components of the baseband signal through orthogonal decomposition; D2: Use a Farrow filter to perform sampling rate conversion and upsample the original data to the target sampling rate.

5. A method for generating a multi-waveform swept signal based on a DAC according to claim 1, characterized in that: The said Step 5 includes: E1: Remove the filter delay from the sampled baseband signal and store it in a data variable; E2: If the set signal type is noise amplitude modulation, noise frequency modulation, sine wave amplitude modulation, sine wave frequency modulation, square wave amplitude modulation, square wave frequency modulation, triangular wave amplitude modulation, triangular wave frequency modulation, sawtooth wave amplitude modulation, sawtooth wave frequency modulation, directly execute Step E3; If the set signal type is noise amplitude modulation swept, sine wave amplitude modulation swept, square wave amplitude modulation swept, triangular wave amplitude modulation swept, sawtooth wave amplitude modulation swept, noise frequency modulation swept, sine wave frequency modulation swept, square wave frequency modulation swept, triangular wave frequency modulation swept, sawtooth wave frequency modulation swept, pure carrier swept, amplitude swept, narrowband swept signal, perform sweeping on the stored signal data; E3: Determine the quantization bits generated by the analog interference signal according to the set signal power and the number of bits of the DAC chip, and normalize the amplitude of the generated swept signal; E4: Store the generated signal data in a data file.

6. A multi-waveform frequency-sweeping signal generating device based on a DAC, characterized in that: The said device includes a setting module, a calculation module, a judgment module, a modulation module, and a judgment and processing module; The setting module: is configured to set the common parameters of the swept-frequency signal, the modulation shape of the interference signal, and the type of the interference signal; The calculation module: is configured to calculate the swept time, calculate the total number of swept points in combination with the sampling rate, and generate corresponding interference signals according to the corresponding interference signal modulation shape setting type; The judgment module: is configured to judge whether the generated signal is a pure swept-frequency signal. If so, it executes the operation of the judgment processing module; otherwise, it executes the operation of the modulation module; The modulation module: is configured to perform AM amplitude modulation or FM frequency modulation on the generated interference signal, and use a filter to change the sampling rate, and sample the original data to the target sampling rate; The judgment processing module: is configured to judge whether the set signal type is the first set signal type or the second set signal type. If it is the first set signal type, it determines the processing according to the set signal power and the number of bits of the DAC chip, and stores the generated signal data. If it is the second set signal type, it performs a sweep on the stored signal data.

7. A multi-waveform sweep signal generating device based on a DAC according to claim 6, characterized in that: The setting module specifically includes the following: A1. Set the common parameters of the swept-frequency signal, including the sampling rate, modulation frequency, center frequency, swept bandwidth swept_bw, swept speed swept_v, modulation depth, and modulation frequency deviation; A2. Set the required modulation shape of the interference signal, including noise, sine wave, square wave, triangular wave, and sawtooth wave; A3. Set the required type of the interference signal, including swept CHIRP, amplitude-modulated swept AM_CHIRP, and frequency-modulated swept FM_CHIRP.

8. The multi-waveform frequency-sweeping signal generating device based on a DAC according to claim 6, characterized in that: The calculation module specifically includes the following: B1. Calculate the swept frequency time according to the swept bandwidth swept_bw and the swept speed swept_v as ; B2. Calculate the total number of swept points according to the sampling rate fs and the swept time swept_t; B3. Generate corresponding noise signals, sine waves, square waves, triangular waves, and sawtooth wave signals according to the corresponding interference signal modulation shape setting type.

9. The multi-waveform frequency-sweeping signal generating device based on DAC according to claim 6, wherein: The modulation module specifically includes the following: D1. Perform AM amplitude modulation or FM frequency modulation on the generated interference signal, and map it to the space composed of the in-phase and quadrature components of the baseband signal through orthogonal decomposition; D2. Use a Farrow filter to perform sampling rate conversion, and upsample the original data to the target sampling rate.

10. A multi-waveform frequency-sweeping signal generating device based on a DAC according to claim 6, characterized in that: The judgment processing module specifically includes the following: E1. Remove the filter delay from the sampled baseband signal and store it in a data variable; E2. If the set signal type is noise amplitude modulation, noise frequency modulation, sine wave amplitude modulation, sine wave frequency modulation, square wave amplitude modulation, square wave frequency modulation, triangular wave amplitude modulation, triangular wave frequency modulation, sawtooth wave amplitude modulation, sawtooth wave frequency modulation, directly execute step E3; If the set signal type is noise amplitude-modulated sweep, sine wave amplitude-modulated sweep, square wave amplitude-modulated sweep, triangular wave amplitude-modulated sweep, sawtooth wave amplitude-modulated sweep, noise frequency-modulated sweep, sine wave frequency-modulated sweep, square wave frequency-modulated sweep, triangular wave frequency-modulated sweep, sawtooth wave frequency-modulated sweep, pure carrier sweep, amplitude sweep, narrowband sweep signal, perform a sweep on the stored signal data; E3. Determine the quantization bits generated by the analog interference signal according to the set signal power and the number of bits of the DAC chip, and normalize the amplitude of the generated swept-frequency signal; E4. Store the generated signal data in a data file.

Images