A DAC-based multi-waveform sweep signal generation method and device

Abstract

The present invention relates to a method and device for generating multi-waveform swept-frequency signals based on a DAC, belonging to the field of signal processing. A fully digital method is used to design and generate interference signals in various relatively complex environmental scenarios, realizing interference signals 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 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, sweep amplitude sweep signals, etc. 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.

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 corresponding forms of signals. 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 diverse and complex electromagnetic interference signals in a complex electromagnetic environment, and has 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 provide a method and device for generating multi-waveform swept-frequency signals based on a DAC, which solves the deficiencies existing in the prior art.

[0005] The purpose of the present invention is achieved through the following technical solutions: A method for generating multi-waveform swept-frequency signals based on a DAC, the method comprising:

[0006] 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;

[0007] 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 corresponding modulation shape setting type of the interference signal;

[0008] 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;

[0009] 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;

[0010] 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, process 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 frequency sweeping on the stored signal data.

[0011] The said Step 1 includes:

[0012] A1. Set the common parameters of the frequency-swept signal, including the sampling rate, modulation frequency, center frequency, swept bandwidth swept_bw, swept speed swept_v, modulation depth, and modulation frequency deviation;

[0013] A2. Set the required modulation shape of the interference signal, including noise, sine wave, square wave, triangular wave, and sawtooth wave;

[0014] A3. Set the required interference signal type, including frequency-swept CHIRP, amplitude-modulated frequency-swept AM_CHIRP, and frequency-modulated frequency-swept FM_CHIRP.

[0015] The said Step 2 includes:

[0016] B1. Calculate the frequency-swept time according to the swept bandwidth swept_bw and the swept speed swept_v as ;

[0017] B2. Calculate the total number of frequency-swept points according to the sampling rate fs and the frequency-swept time swept_t;

[0018] 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.

[0019] The said Step 4 includes:

[0020] 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;

[0021] D2. Use the Farrow filter for sampling rate conversion, and upsample the original data to the target sampling rate.

[0022] The said Step 5 includes:

[0023] E1. Remove the filter delay from the sampled baseband signal and store it in the data variable;

[0024] 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;

[0025] If the signal type is set to 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, then perform frequency sweep on the stored signal data;

[0026] 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;

[0027] E4. Store the generated signal data in a data file.

[0028] A multi-waveform frequency sweep signal generation device based on DAC, the device includes a setting module, a calculation module, a judgment module, a modulation module and a judgment processing module;

[0029] The setting module: is configured to set the common parameters of the frequency sweep signal, the modulation shape of the interference signal and the type of the interference signal;

[0030] The calculation module: is configured to calculate the frequency sweep time, calculate the total number of frequency sweep points in combination with the sampling rate, and generate a corresponding interference signal according to the set type of the corresponding interference signal modulation shape;

[0031] The judgment module: is configured to judge whether the generated signal is a pure frequency sweep signal, if so, execute the operation of the judgment processing module, otherwise execute the operation of the modulation module;

[0032] 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;

[0033] 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, then 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, then perform frequency sweep on the stored signal data.

[0034] The setting module specifically includes the following:

[0035] A1. Set the common parameters of the frequency sweep signal, including sampling rate, modulation frequency, center frequency, swept bandwidth swept_bw, swept speed swept_v, modulation depth and modulation frequency deviation;

[0036] A2. Set the required modulation shape of the interference signal, including noise, sine wave, square wave, triangular wave and sawtooth wave;

[0037] A3. Set the required types of interference signals, including swept CHIRP, amplitude-modulated swept AM_CHIRP, and frequency-modulated swept FM_CHIRP.

[0038] The calculation module specifically includes the following:

[0039] B1. Calculate the swept time according to the swept bandwidth swept_bw and the swept speed swept_v as ;

[0040] B2. Calculate the total number of swept points according to the sampling rate fs and the swept time swept_t;

[0041] B3. Generate corresponding noise signals, sine waves, square waves, triangular waves, and sawtooth wave signals according to the set type of the interference signal modulation shape.

[0042] The modulation module specifically includes the following:

[0043] 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;

[0044] D2. Use the Farrow filter for sampling rate conversion to upsample the original data to the target sampling rate.

[0045] The judgment and processing module specifically includes the following:

[0046] E1. Remove the filter delay from the sampled baseband signal and store it in the data variable;

[0047] 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;

[0048] 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 frequency sweep on the stored signal data;

[0049] 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;

[0050] E4. Store the generated signal data in the data file.

[0051] The present invention has the following advantages: A method and device for generating multi-waveform swept-frequency signals based on a DAC can implement 22 interference signal waveforms in an electromagnetic environment, 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a schematic flow chart of the method of the present invention;

[0053] Figure 2 is a schematic structural diagram of a Farrow filter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are only some of the embodiments of the present application, rather than all of them. Usually, the components of the embodiments of the present application 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 the present application provided below with reference to the accompanying drawings is not intended to limit the protection scope of the present application claimed, but only represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present application. The present invention will be further described below with reference to the accompanying drawings.

[0055] The present invention specifically relates to a method for generating multi-waveform swept-frequency signals based on a DAC, which can flexibly set parameters such as the swept-frequency speed of the signal, and uses a fully digital method to design and generate interference signals in various relatively complex environmental scenarios, implementing 22 interference signal waveforms in an 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 frequency, sine wave amplitude modulation swept frequency, square wave amplitude modulation swept frequency, triangular wave amplitude modulation swept frequency, sawtooth wave amplitude modulation swept frequency, noise frequency modulation swept frequency, sine wave frequency modulation swept frequency, square wave frequency modulation swept frequency, triangular wave frequency modulation swept frequency, sawtooth wave frequency modulation swept frequency, pure carrier swept frequency, and sweep amplitude swept-frequency 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.

[0056] As Figure 1 shown, it specifically includes the following contents:

[0057] (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-modulated swept signal type), and modulation frequency deviation (a parameter specific to the frequency-modulated swept signal type);

[0058] (2) Set the required modulation shape of the interference signal, including NOISE, SINE, SQURE, TRIANGLE, and SAWTOOTH;

[0059] (3) Set the required type of the interference signal, including CHIRP, AM_CHIRP, and FM_CHIRP;

[0060] (4) Calculate the swept time swept_time based on the swept bandwidth swept_bw and the swept speed swept_v:

[0061] ;

[0062] (5) Calculate the total number of swept points based on the sampling time interval f s and the swept time swept_t;

[0063] (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 types of signals: noise signal, sine wave, square wave, triangular wave, and sawtooth wave. The generation methods are as follows:

[0064] (a) Noise signal: Generate Gaussian white noise across the entire frequency band and filter it to generate a noise signal with a specified bandwidth;

[0065] (b) The mathematical expression of the sine wave signal is:

[0066] ;

[0067] (c) The mathematical expression of the square wave signal is:

[0068] ;

[0069] (d) The mathematical expression of the triangular wave signal is:

[0070] ;

[0071] (e) The mathematical expression of the sawtooth wave signal is:

[0072] ;

[0073] where T is the symbol period and t represents the time variable.

[0074] (7) If it is a simple frequency-swept signal, that is, a pure carrier frequency-swept or amplitude-swept frequency signal, through the method of quadrature modulation, the real part is the generated signal and the imaginary part is 0, then go to step (10);

[0075] (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 quadrature decomposition;

[0076] 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:

[0077] ,

[0078] In the formula, is the modulation index, and the range is between . If , the envelope of the modulated wave will have serious distortion and cannot restore the original waveform of the modulation signal, that is, overmodulation occurs. For the interference signal to achieve quadrature modulation, the real and imaginary parts of AM are shown as follows:

[0079] ,

[0080] .

[0081] 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:

[0082] ,

[0083] After expansion and simplification, it is obtained:

[0084] ,

[0085] Among them, is the carrier angular frequency, is the modulation noise, sine wave, square wave, triangular wave, sawtooth wave signal, is the modulation angular frequency deviation, and the phase deviation is given by the following formula:

[0086] .

[0087] To achieve FM, the modulation signal is integrated, and then the sine and cosine are taken separately for the integrated signal. When implemented by the quadrature modulation method:

[0088] ,

[0089] ;

[0090] When implemented in the digital domain, the above formula is digitized:

[0091] ,

[0092] .

[0093] (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 filter coefficients 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. From Figure 2 it can be seen that each output is calculated from 4 inputs. This set of inputs first passes through several sub-filters to obtain , and then is multiplied and added with through a series of 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.

[0094] Table 1. Farrow filter system table

[0095]

[0096] Among them, 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.

[0097] (10) Remove the filter delay from the sampled baseband signal and store it in a data variable;

[0098] (11) Perform frequency sweeping, i.e., chirp processing, on the stored signal data. The mathematical expression for chirping is:

[0099] ,

[0100] 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.

[0101] Performing frequency sweeping on the amplitude-modulated or frequency-modulated signal again can be expressed as:

[0102] ,

[0103] When implemented using orthogonal modulation, the in-phase branch and the quadrature branch can be respectively expressed as:

[0104] ,

[0105] ,

[0106] where n represents the time variable after digital discretization, S chirp (n) represents S chirp the discrete signal of

[0107] (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 generating 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.

[0108] (13) Store the finally generated signal data in a data file.

[0109] The above is only the preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and improvements, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in related fields. And any changes and variations made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A method for generating a multi-waveform swept-frequency signal based on a DAC, characterized in that: The method comprises: Step 1: Set the common parameters of the sweep signal, the interference signal modulation shape and the interference signal type; Step 2: Calculate the sweep time and the total number of sweep points in combination with the sampling rate, and generate the corresponding interference signal according to the corresponding interference signal modulation shape setting type; Step 3: determine whether the generated signal is a simple frequency sweep signal, if so, perform the operation of step 5, otherwise perform the operation of 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 to sample the original data to the target sampling rate; Step 5: Determine whether the signal type is the first set signal type or the second set signal type. If it is the first set signal type, process it 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 frequency sweep on the stored signal data. The step five includes: E1. Remove the filter delay from the sampled baseband signal and store it in the data variable; E2. If the signal type is set to noise AM, noise FM, sine wave AM, sine wave FM, square wave AM, square wave FM, triangle wave AM, triangle wave FM, sawtooth wave AM, or sawtooth wave FM, go directly to step E3; If the signal type is set to noise AM sweep, sine AM sweep, square AM sweep, triangle AM sweep, sawtooth AM sweep, noise FM sweep, sine FM sweep, square FM sweep, triangle FM sweep, sawtooth FM sweep, pure carrier sweep, amplitude sweep, or narrowband sweep, the stored signal data will be swept. E3. Determine the quantization bit number of 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 sweep signal; E4. Store the generated signal data in a data file.

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

3. A method for generating a multi-waveform swept signal based on a DAC according to claim 1, characterized in that: The second step 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 sweep points based on the sampling rate fs and the sweep time swept_t; B3. Set the type according to the corresponding interference signal modulation shape to generate corresponding noise signal, sine wave, square wave, triangle wave, and sawtooth wave signal.

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

5. A multi-waveform swept-frequency signal generating device based on a DAC, characterized in that: 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 frequency-swept signal, the modulation shape of the interference signal, and the type of the interference signal; The calculation module: is configured to calculate the frequency-swept time, calculate the total number of frequency-swept points in combination with the sampling rate, and generate a corresponding interference signal according to the set type of the corresponding interference signal modulation shape; The judgment module: is configured to judge whether the generated signal is a pure frequency-swept 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 frequency sweeping on the stored signal data; 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 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, noise frequency modulation frequency sweep, sine wave frequency modulation frequency sweep, square wave frequency modulation frequency sweep, triangular wave frequency modulation frequency sweep, sawtooth wave frequency modulation frequency sweep, pure carrier frequency sweep, amplitude sweep frequency sweep, narrowband frequency sweep signal, perform frequency 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 frequency-swept signal; E4. Store the generated signal data in a data file.

6. The multi-waveform sweep signal generating device based on DAC according to claim 5, wherein: The setting module specifically includes the following: A1. Set the common parameters of the frequency-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 frequency sweep CHIRP, amplitude modulation frequency sweep AM_CHIRP, and frequency modulation frequency sweep FM_CHIRP.

7. A multi-waveform frequency-sweeping signal generating device based on a DAC according to claim 5, 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 frequency-swept points according to the sampling rate fs and the frequency-swept time swept_t; B3. Generate corresponding noise signals, sine waves, square waves, triangular waves, and sawtooth wave signals according to the set type of the corresponding interference signal modulation shape.

8. The multi-waveform sweep signal generating device based on a DAC according to claim 5, characterized in that: 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 for sample rate conversion to upsample the original data to the target sample rate.

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