CN113759318B - Automatic identification method for radar signal intra-pulse modulation type - Google Patents
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- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000009825 accumulation Methods 0.000 claims description 17
- 238000004364 calculation method Methods 0.000 claims description 11
- 238000005070 sampling Methods 0.000 claims description 11
- 238000001914 filtration Methods 0.000 claims description 7
- 238000007619 statistical method Methods 0.000 claims description 4
- 230000009191 jumping Effects 0.000 claims description 3
- 238000001228 spectrum Methods 0.000 description 17
- 230000000630 rising effect Effects 0.000 description 5
- 238000012935 Averaging Methods 0.000 description 3
- 230000035772 mutation Effects 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
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- 230000000977 initiatory effect Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/28—Details of pulse systems
Abstract
An automatic identification method for the type of modulation in radar signal pulse. The method comprises the following steps: s1: reading the sampled radar signal; s2: according to the sampled radar signals, solving a radar signal starting point, a radar signal ending point and a radar signal pulse width; s3: setting a broadband frequency modulation signal bandwidth threshold value on a frequency domain, and calculating a signal center frequency I and a signal bandwidth I through FFT operation; s4: s3, judging whether the first signal bandwidth is larger than a set bandwidth threshold; s4.1: judging that the signal bandwidth is a simple pulse, phase coding or narrowband frequency modulation signal if the signal bandwidth is smaller than a set bandwidth threshold; s4.2: the first signal bandwidth is larger than the set bandwidth threshold; s4.25: judging whether sinusoidal frequency modulation is carried out according to the frequency modulation slope; s4.251: if yes, carrying out sine-solving period; s4.252: if not, polynomial fitting is carried out to obtain the frequency modulation rule. The invention greatly reduces the probability of misjudgment of the phase modulation type and the code element width caused by false frequency hopping generated by noise.
Description
Technical Field
The invention relates to a radar signal intra-pulse modulation method, in particular to an automatic identification method for the type of the radar signal intra-pulse modulation.
Background
The identification of the modulation type in the radar signal pulse is an important component of a modern electronic reconnaissance system, and at present, the automatic identification of the modulation type in the radar signal pulse sometimes has the situation of wrong identification type:
on one hand, misjudgment is caused by unobvious characteristics of the pulse modulation type, for example, the pulse modulation bandwidth of the linear frequency modulation signal is narrow, and the linear frequency modulation signal is easy to judge as a simple pulse signal;
on the other hand, because the signal to noise ratio is lower, frequency jump caused by noise exists on a time-frequency curve of the signal, and misjudgment of a pulse modulation type or a modulation parameter is caused, for example, a large noise signal exists in a phase coding signal, and frequency jump caused by noise exists on a time-frequency curve of the phase coding signal, and misjudgment of a phase coding type or a code element width is caused.
The judgment of the signal bandwidth and the time-frequency curve is one of the main methods for automatically identifying the modulation type in the radar signal at present. The bandwidth of a simple pulse signal (no modulation in the pulse) is very narrow, but the bandwidth is also large when the pulse width is very narrow, according to the time-width-bandwidth product of the simple pulse being approximately 1, i.e. bτ=1 (B is the bandwidth, τ is the time width, i.e. the pulse width). The bandwidths of the linear frequency modulation signals or the non-linear frequency modulation signals are wider, the bandwidths of the phase coding signals are narrower, and frequency hopping and the like can occur on a time-frequency curve of the phase coding signals at a phase hopping point. These rules can be used to identify the type of modulation within the radar signal.
Taking a time-frequency curve as an example, as shown in fig. 1-4; the method is respectively a positive frequency modulation linear frequency modulation signal time-frequency curve, a parabolic nonlinear frequency modulation signal time-frequency curve, a 7-bit Baker code two-phase coding signal time-frequency curve and a 13-bit Baker code four-phase coding signal time-frequency curve. Since the pulse is a single frequency signal, the time-frequency curve of a simple pulse signal (no modulation in the pulse) is a horizontal straight line.
However, the intra-pulse modulation characteristic of the radar signal is not obvious, for example, the intra-pulse modulation bandwidth of the chirp signal is narrow, and the slope of the time-frequency curve is not as large as that of the time-frequency curve in fig. 1, so that it is difficult to determine whether the radar signal is a simple pulse signal or a chirp signal. Or, a noise signal is attached to the radar signal, and then a false frequency jump is caused on a time-frequency curve, such as the time-frequency curve of the actually measured 13-bit barker code two-phase coded signal shown in fig. 5, in the figure, a 4-point (a 2 nd vertical line below the horizontal reference line, a 2 nd vertical line from left to right above the horizontal reference line and an 8 th vertical line) with a lower frequency jump amplitude is a false frequency jump, and may be misjudged as a four-phase coded signal during automatic identification.
Disclosure of Invention
Aiming at the problems, the invention provides an automatic identification method for the intra-pulse modulation type of a radar signal, which improves the identification accuracy of the radar.
The technical scheme of the invention is as follows: an automatic identification method for the type of modulation in radar signal pulse, comprising the following steps:
s1: reading the sampled radar signal;
s2: according to the sampled radar signals, solving a radar signal starting point, a radar signal ending point and a radar signal pulse width;
s3: setting a broadband frequency modulation signal bandwidth threshold value on a frequency domain, and calculating a signal center frequency I and a signal bandwidth I through FFT operation;
s4: s3, judging whether the first signal bandwidth is larger than a set bandwidth threshold;
s4.1: judging that the signal bandwidth is a simple pulse, phase coding or narrowband frequency modulation signal if the signal bandwidth is smaller than a set bandwidth threshold;
s4.11: squaring the sampling signal, and calculating a second signal center frequency and a second signal bandwidth through FFT operation;
s4.12: comparing the second signal bandwidth with the first signal bandwidth;
s4.121: when the comparison value in the step S4.12 is between 0.8 and 1.2, judging that the pulse signal is a simple pulse signal;
s4.122: when the second signal bandwidth is larger than 1.2 times of the first signal bandwidth, judging that the second signal bandwidth is a narrowband frequency modulation signal, and executing the step S4.22 in a jumping manner;
s4.123: when the second signal bandwidth is smaller than 0.8 times of the first signal bandwidth, judging the second signal bandwidth as a phase coding signal; selecting the pulse accumulation number, and sequentially carrying out pulse accumulation, time-frequency curve calculation, frequency hopping point calculation, amplitude and histogram statistical analysis;
s4.2: the first signal bandwidth is larger than the set bandwidth threshold;
s4.21: judging the sampled radar signal as a bandwidth frequency modulation signal;
s4.22: solving a time-frequency curve of the radar signal in the step S4.21, and filtering through a median;
s4.23: judging whether the time-frequency curve passing through the median filtering is linear frequency modulation according to the frequency modulation slope;
s4.231: if yes, the frequency modulation index is calculated;
s4.232: if not, the step S4.24 is carried out;
s4.24: judging whether the frequency modulation slope is triangular frequency modulation or not according to the frequency modulation slope;
s4.241: if yes, then the positive and negative frequency modulation slope is calculated;
s4.242: if not, the step S4.25 is carried out;
s4.25: judging whether sinusoidal frequency modulation is carried out according to the frequency modulation slope;
s4.251: if yes, carrying out sine-solving period;
s4.252: if not, polynomial fitting is carried out to obtain the frequency modulation rule.
And when step S4.123 analyzes a jump amplitude through a histogram system, judging the jump amplitude as a two-phase coding signal, and obtaining a coding rule and a horse element width.
And when the step S4.123 analyzes three jump amplitudes through a histogram system, judging the jump amplitudes as four-phase coded signals, and obtaining a coding rule and a horse element width.
Aiming at the problems, the invention provides an automatic identification method of the pulse modulation type, which reduces the identification error probability of the pulse modulation type through the improvement of the following two aspects:
1. the spectrum is obtained after the signal is squared, and the change rule between the spectrum bandwidth of the modulated signal with different types after the signal is squared and the spectrum bandwidth of the original signal is utilized to be different, so that the modulated signal is accurately classified into corresponding types, such as simple pulse, frequency modulation signal, phase coding signal and the like, when the modulation type in the signal pulse is initially classified;
2. after the primary classification is accurately carried out, denoising is carried out on the method which is judged to be the phase coding signal and can be used for sampling and accumulating multiple pulses, the signal to noise ratio is improved, and then the time-frequency curve is obtained, so that the probability of misjudgment of the phase modulation type and the code element width caused by false frequency hopping generated by noise is greatly reduced.
Drawings
Figure 1 is a time-frequency plot of a prior art positive fm chirp,
figure 2 is a time-frequency plot of a parabolic non-chirped signal in the background,
figure 3 is a time-frequency graph of a 7-bit barker code two-phase encoded signal in the background art,
figure 4 is a time-frequency plot of a 13-bit barker code four-phase encoded signal in the background art,
figure 5 is a time-frequency plot of a two-phase encoded signal of a 13-bit barker code as found in the prior art,
figure 6 is a simple pulse signal spectrum,
figure 7 is a simple pulse signal squared spectrum,
figure 8 is a two-phase encoded signal spectrum,
figure 9 is a spectrum of a two-phase encoded signal squared,
figure 10 is a chirp spectrum,
figure 11 is a frequency spectrum of a chirped signal squared,
figure 12 is a straight line approach to approximate zero crossings,
figure 13 is a pulse 1 signal waveform,
figure 14 is a pulse 2 signal waveform,
figure 15 is a waveform of the signal after aligned accumulation averaging,
fig. 16 is a main flow chart of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
The invention discloses a method for automatically identifying the modulation type in a radar signal pulse, which is shown in fig. 6-16 and comprises the following steps:
s1: reading the sampled radar signal;
s2: according to the sampled radar signals, solving a radar signal starting point, a radar signal ending point and a radar signal pulse width; the calculation of the starting point, the ending point and the pulse width of the radar signal belongs to the prior art;
s3: setting a broadband frequency modulation signal bandwidth threshold value on a frequency domain, and calculating a signal center frequency I and a signal bandwidth I through FFT (fast Fourier transform) operation; the first signal center frequency and the first signal bandwidth belong to the prior art;
s4: s3, judging whether the first signal bandwidth is larger than a set bandwidth threshold;
s4.1: judging that the signal bandwidth is a simple pulse, phase coding or narrowband frequency modulation signal if the signal bandwidth is smaller than a set bandwidth threshold;
s4.11: squaring the sampling signal, and calculating a second signal center frequency and a second signal bandwidth through FFT operation;
s4.12: comparing the second signal bandwidth with the first signal bandwidth (the second signal bandwidth is the first signal bandwidth) to determine whether the second signal bandwidth is in the range of 0.8-1.2 times;
s4.121: when the comparison value of the step S4.12 is between 0.8 and 1.2 (comprising 0.8 and 1.2), judging that the pulse signal is a simple pulse signal;
s4.122: when the second signal bandwidth is larger than 1.2 times of the first signal bandwidth, judging that the second signal bandwidth is a narrowband frequency modulation signal, and executing the step S4.22 in a jumping manner;
s4.123: when the second signal bandwidth is smaller than 0.8 times of the first signal bandwidth, judging the second signal bandwidth as a phase coding signal; selecting the pulse accumulation number, and sequentially carrying out pulse accumulation, time-frequency curve calculation, frequency hopping point calculation, amplitude and histogram statistical analysis;
s4.2: the first signal bandwidth is larger than the set bandwidth threshold;
s4.21: judging the sampled radar signal as a bandwidth frequency modulation signal;
s4.22: the time-frequency curve of the radar signal of step S4.21 is obtained, and through median filtering,
s4.23: judging whether the time-frequency curve passing through the median filtering is linear frequency modulation according to the frequency modulation slope;
s4.231: if yes, the frequency modulation index is calculated;
s4.232: if not, the step S4.24 is carried out;
s4.24: judging whether the frequency modulation slope is triangular frequency modulation or not according to the frequency modulation slope;
s4.241: if yes, then the positive and negative frequency modulation slope is calculated;
s4.242: if not, the step S4.25 is carried out;
s4.25: judging whether sinusoidal frequency modulation is carried out according to the frequency modulation slope;
s4.251: if yes, carrying out sine-solving period;
s4.252: if not, polynomial fitting is carried out to obtain the frequency modulation rule.
And when step S4.123 analyzes a jump amplitude through a histogram system, judging the jump amplitude as a two-phase coding signal, and obtaining a coding rule and a horse element width.
And when the step S4.123 analyzes three jump amplitudes through a histogram system, judging the jump amplitudes as four-phase coded signals, and obtaining a coding rule and a horse element width.
And when step S4.123 is analyzed by a histogram system to be not in one jump amplitude and three jump amplitudes, the unknown signal is directly judged.
The invention firstly squares the signal and then obtains the frequency spectrum, and utilizes the difference of the change rule between the frequency spectrum bandwidth of the signal subjected to different types of modulation and the frequency spectrum bandwidth of the original signal, thereby accurately classifying the modulation types in the signal pulse into corresponding types, such as simple pulse, frequency modulation signal, phase coding signal and the like, and reducing the error judgment probability.
The principle of the method is as follows:
the general mathematical expression for a pulse-modulated pulse signal is:
wherein: f (f) 0 For the carrier frequency of the signal,a (t) is a pulse envelope function, which is a phase modulation function;
a (t) =a when the pulse envelope is a rectangular pulse m Rect(t/τ 0 )，A m For pulse amplitude τ 0 Is the pulse width.
When (when)In different cases, S (t) represents different intra-pulse modulations:
1. when (when)When S (t) represents a simple pulse signal;
2. when (when)K is the frequency modulation slope, S (t) is the chirp signal;
3. when (when)At time C a And (t) is a phase encoding function, and S (t) represents a phase encoding signal.
In the above-mentioned formula(s),is the initial phase of the signal.
Now signal the signalSquaring to obtain:
wherein A is 2 And (t) is a direct current or slowly varying signal, the frequency of which is far smaller than the frequency of the signal, and thus the signal is positioned in a low frequency region in the frequency spectrum, and the frequency spectrum analysis of the signal is not affected.
Thus: when (when)When (I)>Therefore, the signal center frequency after the square of the simple pulse signal is the original signal center frequencyThe bandwidth is then the same as the original signal by a factor of 2.
When (when)When (I)>Therefore, the signal center frequency of the square linear frequency modulation signal is 2 times of the original signal center frequency, and the bandwidth is 2 times of the original signal bandwidth.
When (when)When (I)>
Taking a two-phase coded signal as an example, C a (t)＝±1；
Thus (2)Therefore, the signal center frequency of the two-phase coded signal after squaring is 2 times of the original signal center frequency, and the bandwidth is the same as that of the simple pulse signal.
Therefore, the change rule between the spectrum bandwidth of the modulated signals with different types after squaring is different from that of the original signals, and the modulated signals are accurately classified into corresponding categories when the modulation types in the signal pulses are initially classified.
Simulation example:
the invention respectively adopts a simple pulse signal with the intermediate frequency of 150MHz, a 7-bit Baker code two-phase coding signal and a linear frequency modulation signal with the frequency modulation bandwidth of 5MHz for simulation;
the sampling rate is 1200MHz, the pulse width is 4096 points, and the spectrum of the original signal and the spectrum of the squared signal are obtained respectively, as shown in fig. 6-11. The bandwidth of the linear frequency modulation signal is 5MHz, so that the frequency spectrum and the bandwidth change of the signal are displayed more clearly and are easy to distinguish when the linear frequency modulation signal is plotted.
As can be seen from fig. 6 to 11, the center frequency after squaring all types of signals is 2 times that of the original signal, but the bandwidth after squaring the simple pulse signal is almost the same as that of the original signal, the bandwidth after squaring the two-phase encoded signal is almost the same as that of the simple pulse signal, and the bandwidth after squaring the chirp signal is almost 2 times that of the original signal.
The invention further adopts the accumulated denoising of the multiple pulses to improve the signal to noise ratio, thereby reducing the probability of error identification of the type of the phase coding signal and the code element width.
The premise of pulse accumulation is that pulse alignment is necessary, and different numbers of pulses participating in accumulation can be selected according to different signal to noise ratios of signals. The pulse alignment method adopted by the invention is as follows: if all pulse initiation portions involved in pulse accumulation have rising edges with zero crossings, accumulation occurs with rising edge zero crossing alignment, otherwise accumulation occurs with falling edge zero crossing alignment.
In order to accurately determine the zero crossing of the rising or falling edge of the signal, it is required to have at least four samples per signal period, i.e. the sampling frequency fs is at least the highest frequency F of the signal intermediate frequency m 4 times of (2). In order to meet the real-time requirement of the system, the zero crossing point time calculation is simple and direct by using a linear method. The zero crossing point is between two adjacent data points, namely a positive data point and a negative data point, the two points are connected into a straight line, and the intersection point with the time axis is an approximate zero crossing point, and the falling edge zero crossing point is calculated as an example, as shown in fig. 12.
Let t be 1 And t 2 The sampled value of these two points at the moment is x 1 And x 2 Then the linear equation passing through the two points isThe value of t at the intersection of this line with x=0 is the zero crossing time:
the data points between the adjacent positive data and the adjacent negative data around the zero crossing point are changed according to the sine rule, and the straight line is used for approaching the zero crossing point, so that the error exists certainly, and whether the introduced error is acceptable for analyzing the signal parameters or not needs to be analyzed.
Let n samples be taken per cycle,x 1 =sint, then->The zero crossing time t 'is approximated according to the zero crossing time formula (1)' z With the actual zero crossing time t z The error e (t) of (c) is:
in the formula (2), for the convenience of calculation, it is assumed that the sampling period is an integer multiple of the signal period
Deriving e (t) and then making it zero, the value of t when the error is maximum can be obtained:
in the formula (3), n is the number of sampling points per cycle. From (3)Substituting t into (2) to obtain the maximum error e (t) between the approximate zero crossing point and the actual zero crossing point in the sampling period (n)max Further, the relative error can be obtained. When n=4, 6, 8, the approximate zero-crossing point and the actual zero-crossing point t can be obtained respectively z The relative errors of (a) are respectively: 2.42%, 0.62% and 0.23%. From this, it is seen that the error of approximating the zero crossing point time with a straight line significantly decreases with the increase of the sampling times per cycle, and the sampling point number per cycle is generally 6, which completely meets the requirement of signal accumulation analysis.
The invention performs alignment accumulation on 2 pulses of the actually sampled chirp signal with the bandwidth of 2.3MHz according to the method, as shown in fig. 13-15. Fig. 13 is a signal waveform of pulse 1, fig. 14 is a signal waveform of pulse 2, and fig. 15 is a signal waveform after aligned accumulation and averaging.
As can be seen from fig. 13 to 14, due to the added noise, the rising edge and the falling edge of the signal or the top and the bottom of the signal have obvious mutation points, and after accumulation and averaging are performed by using only 2 pulses, the rising edge and the falling edge of the signal or the top and the bottom of the signal have obvious mutation point amplitudes which are obviously reduced or even disappear. The signal-to-noise ratio of the time-frequency curve of the subsequent signal is greatly improved, false frequency hopping points are eliminated, and the misjudgment rate of the phase coding signal is greatly reduced.
According to the analysis result, the invention provides an automatic identification method aiming at the currently commonly used radar signal intra-pulse modulation type, which comprises the following steps:
(1) Reading the sampled radar signal;
(2) Performing FFT operation on the signal to obtain the center frequency and bandwidth of the signal;
(3) Setting a bandwidth threshold of the broadband frequency-modulated signal, such as 2.5MHz, if the bandwidth of the signal is larger than the set threshold, directly judging the signal as the frequency-modulated signal, entering a frequency-modulated signal identification flow, otherwise judging the signal as a simple pulse signal, a narrowband frequency-modulated signal or a phase code signal;
(4) If the frequency modulation signal identification flow is entered, a time-frequency curve of the signal is obtained, and median filtering is carried out on the time-frequency curve, so that false frequency hopping caused by noise is eliminated; judging whether the signal is a linear frequency modulation signal, if so, judging whether the signal is positive frequency modulation or negative frequency modulation, and calculating parameters such as frequency modulation index, bandwidth and the like; if the non-linear frequency modulation is judged, judging whether the non-linear frequency modulation is triangular frequency modulation, if so, calculating parameters such as positive and negative frequency modulation indexes, total bandwidth, sub-bandwidth and the like; if the frequency modulation type is not the frequency modulation type, the frequency modulation type can be directly judged as a non-linear frequency modulation signal according to the requirement, or polynomial fitting is carried out to obtain a non-linear frequency modulation rule;
(5) If a simple pulse signal, a narrow-band frequency modulation signal or a phase coding signal identification flow is entered, firstly squaring the signal, then carrying out FFT operation on the squared signal, calculating the center frequency and the bandwidth, and then comparing the calculated bandwidth with the bandwidth obtained by the original signal; if the bandwidths are close to the same, judging the signal as a simple signal; if the bandwidth is more than 1.5 times of the original signal bandwidth, judging the signal to be a narrowband frequency modulation signal, and then continuing to analyze the frequency modulation type and parameters by referring to a wideband frequency modulation signal identification flow; if the bandwidth is smaller than 0.5 times of the original signal bandwidth, judging the signal as a phase coding signal, then carrying out pulse accumulation denoising, obtaining a signal time-frequency curve, carrying out histogram statistical analysis on the amplitude of a frequency hopping point of the time-frequency curve, further judging the signal as a two-phase coding signal or a four-phase coding signal, and obtaining parameters such as a coding type, a subcode width, a code element rate and the like.
For the purposes of this disclosure, the following points are also described:
(1) The drawings of the embodiments disclosed in the present application relate only to the structures related to the embodiments disclosed in the present application, and other structures can refer to common designs;
(2) The embodiments disclosed herein and features of the embodiments may be combined with each other to arrive at new embodiments without conflict;
the above is only a specific embodiment disclosed in the present application, but the protection scope of the present disclosure is not limited thereto, and the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (3)
1. The automatic identification method for the radar signal intra-pulse modulation type is characterized by comprising the following steps:
s1: reading the sampled radar signal;
s2: according to the sampled radar signals, solving a radar signal starting point, a radar signal ending point and a radar signal pulse width; the calculation of the starting point, the ending point and the pulse width of the radar signal can be obtained through conventional calculation;
s3: setting a broadband frequency modulation signal bandwidth threshold value on a frequency domain, and calculating a signal center frequency I and a signal bandwidth I through FFT operation;
s4: s3, judging whether the first signal bandwidth is larger than a set bandwidth threshold;
s4.1: judging that the signal bandwidth is a simple pulse, phase coding or narrowband frequency modulation signal if the signal bandwidth is smaller than a set bandwidth threshold;
s4.11: squaring the sampling signal, and calculating a second signal center frequency and a second signal bandwidth through FFT operation;
s4.12: comparing the second signal bandwidth with the first signal bandwidth;
s4.121: when the comparison value in the step S4.12 is between 0.8 and 1.2, judging that the pulse signal is a simple pulse signal;
s4.122: when the second signal bandwidth is larger than 1.2 times of the first signal bandwidth, judging that the second signal bandwidth is a narrowband frequency modulation signal, and executing the step S4.22 in a jumping manner;
s4.123: when the second signal bandwidth is smaller than 0.8 times of the first signal bandwidth, judging the second signal bandwidth as a phase coding signal; selecting the pulse accumulation number, and sequentially carrying out pulse accumulation, time-frequency curve calculation, frequency hopping point calculation, amplitude and histogram statistical analysis;
s4.2: the first signal bandwidth is larger than the set bandwidth threshold;
s4.21: judging the sampled radar signal as a bandwidth frequency modulation signal;
s4.22: solving a time-frequency curve of the radar signal in the step S4.21, and filtering through a median;
s4.23: judging whether the time-frequency curve passing through the median filtering is linear frequency modulation according to the frequency modulation slope;
s4.231: if yes, the frequency modulation index is calculated;
s4.232: if not, the step S4.24 is carried out;
s4.24: judging whether the frequency modulation slope is triangular frequency modulation or not according to the frequency modulation slope;
s4.241: if yes, then the positive and negative frequency modulation slope is calculated;
s4.242: if not, the step S4.25 is carried out;
s4.25: judging whether sinusoidal frequency modulation is carried out according to the frequency modulation slope;
s4.251: if yes, carrying out sine-solving period;
s4.252: if not, polynomial fitting is carried out to obtain the frequency modulation rule.
2. The method according to claim 1, wherein when step S4.123 analyzes a jump amplitude through a histogram system, it is determined that the jump amplitude is a two-phase code signal, and a code rule and a mark width are calculated.
3. The method for automatically identifying the intra-pulse modulation type of the radar signal according to claim 1, wherein when three jump amplitudes are analyzed by a histogram system in step S4.123, the four-phase code signal is determined, and the code rule and the mark width are calculated.
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| CN110412512A (en) * | 2019-08-08 | 2019-11-05 | 唐晓杰 | A kind of radar signal intra-pulse modulation characteristic analysis method |
| CN113009420A (en) * | 2021-02-02 | 2021-06-22 | 中山大学 | Method and system for processing slice forwarding interference signal and storage medium |
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| CN110412512A (en) * | 2019-08-08 | 2019-11-05 | 唐晓杰 | A kind of radar signal intra-pulse modulation characteristic analysis method |
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