阅读说明：本技术 一种气溶胶环境下激光引信的定距方法 (Laser fuse spacing method in aerosol environment ) 是由 宋承天 张垚彦 刘博虎 于 2020-04-19 设计创作，主要内容包括：本发明公开了一种气溶胶环境下激光引信的定距方法,通过对引信接收到的差频信号及参考差频信号进行互相关熵谱密度运算处理,使引信能更有效地从被气溶胶悬浮粒子干扰的信号中,分离出有效的目标信息,通过选择优化互相关熵谱密度运算的参数达到提高引信定距精度的目的,提高了激光引信抗气溶胶悬浮粒子干扰的能力。(The invention discloses a distance method of a laser fuse in an aerosol environment, which can separate effective target information from a signal interfered by aerosol suspended particles more effectively by performing cross-correlation entropy spectrum density operation processing on a difference frequency signal received by the fuse and a reference difference frequency signal, achieves the purpose of improving the distance precision of the fuse by selecting and optimizing parameters of the cross-correlation entropy spectrum density operation, and improves the capability of the laser fuse for resisting the interference of the aerosol suspended particles.)

1. A distance method of a laser fuse in an aerosol environment is characterized by comprising the following steps:

step 1, calculating according to a set distance to obtain a reference frequency, and generating a reference difference frequency signal corresponding to the reference frequency; generating an actually measured difference frequency signal of a current target echo;

step 2, calculating the cross-correlation entropy of the reference difference frequency signal and the measured difference frequency signal, and performing discrete Fourier transform on the cross-correlation entropy to obtain the spectrum density of the cross-correlation entropy; adding all the values of the cross-correlation entropy spectrum density to obtain a sum of the cross-correlation entropy spectrum density;

step 3, when the sum of the cross-correlation entropy spectrum densities is larger than or equal to a set threshold value, executing step 4; when the cross-correlation entropy spectrum density sum is smaller than the threshold value, receiving a next target echo, and executing the step 1;

step 4, if the continuous execution times of the step 4 is larger than or equal to the set execution time threshold, executing a step 5; if the continuous execution times of the step 4 is less than the execution time threshold, calculating the distance between the fuze and the fuse in the detection time interval according to the movement speed of the fuze and the detection time interval, updating the distance by using the difference between the distance and the distance, and executing the step 1;

and 5, outputting a detonation signal and igniting the fuse.

2. The method of claim 1, wherein the threshold number of executions is 5 or 6.

Technical Field

The invention belongs to the technical field of laser fuse spacing, and particularly relates to a laser fuse spacing method in an aerosol environment.

Background

The carrier modulated continuous wave laser detection technology is gradually applied to fuzes, but in practical application, the carrier modulated continuous wave laser detection technology is interfered by aerosol suspended particles generated in natural and battlefield environments, such as smoke, fog, rain, sand dust and the like. In these aerosol environments, the laser echo signal is easily affected by aerosol particles, so that the fuse cannot acquire the laser echo signal or the acquired laser echo signal has an error, thereby causing the fuse to explode or fail.

For the carrier modulation continuous wave laser fuse, a difference frequency signal spectrum comprises a target echo signal, a smoke interference signal and random noise, and a plurality of target and interference spectrum peaks can be formed. Without suspended particle interference, the target spectral peak is distinct and energy concentrated. If the backscattering interference of the suspended particles is strong, the energy of a target signal is relatively weak, and a target spectrum peak of the target signal can be submerged by the interference, so that the fuze cannot be fixed because whether the designated frequency point is the target signal spectrum peak or not cannot be judged.

In conclusion, in an aerosol environment, the existing laser fuze technology has the problem of low distance precision.

Disclosure of Invention

In view of this, the present invention provides a method for positioning a laser fuse in an aerosol environment, which can achieve precise positioning of the laser fuse under the interference of aerosol suspended particles.

The invention provides a distance method of a laser fuse in an aerosol environment, which comprises the following steps:

step 1, calculating according to a set distance to obtain a reference frequency, and generating a reference difference frequency signal corresponding to the reference frequency; generating an actually measured difference frequency signal of a current target echo;

step 2, calculating the cross-correlation entropy of the reference difference frequency signal and the measured difference frequency signal, and performing discrete Fourier transform on the cross-correlation entropy to obtain the spectrum density of the cross-correlation entropy; adding all the values of the cross-correlation entropy spectrum density to obtain a sum of the cross-correlation entropy spectrum density;

step 3, when the sum of the cross-correlation entropy spectrum densities is larger than or equal to a set threshold value, executing step 4; when the cross-correlation entropy spectrum density sum is smaller than the threshold value, receiving a next target echo, and executing the step 1;

step 4, if the continuous execution times of the step 4 is larger than or equal to the set execution time threshold, executing a step 5; if the continuous execution times of the step 4 is less than the execution time threshold, calculating the distance between the fuze and the fuse in the detection time interval according to the movement speed of the fuze and the detection time interval, updating the distance by using the difference between the distance and the distance, and executing the step 1;

and 5, outputting a detonation signal and igniting the fuse.

Further, the execution number threshold is 5 or 6.

Has the advantages that:

the invention can separate effective target information from the signal interfered by aerosol suspended particles more effectively by performing cross-correlation entropy spectrum density operation processing on the difference frequency signal received by the fuze and the reference difference frequency signal, achieves the purpose of improving the fuze distance precision by selecting and optimizing the parameters of cross-correlation entropy spectrum density operation, and improves the capability of the laser fuze for resisting the interference of the aerosol suspended particles.

Drawings

Fig. 1 is a schematic diagram of a spacing method of a laser fuse in an aerosol environment according to the present invention.

Fig. 2(a) is a graph of a difference frequency echo signal of a carrier modulated continuous wave laser fuse in an aerosol environment with high visibility.

Fig. 2(b) is a graph of a difference frequency echo signal of a carrier modulated continuous wave laser fuse in an aerosol environment with low visibility.

Fig. 3(a) is a processing result diagram of the distance target 3m of the distance method of the laser fuse in the aerosol environment according to the present invention.

Fig. 3(b) is a processing result diagram of a distance target 5m of the laser fuse distance determination method in an aerosol environment according to the present invention.

Fig. 3(c) is a processing result diagram of the distance target 9m of the laser fuse distance determination method in the aerosol environment according to the present invention.

Detailed Description

The invention is described in detail below by way of example with reference to the accompanying drawings.

The invention provides a distance method of a laser fuse in an aerosol environment, which has the basic idea that whether a difference frequency signal and a reference difference frequency signal are similar or not is judged by analyzing the cross-correlation entropy spectrum density characteristics of the actually measured difference frequency signal and the reference difference frequency signal of the fuse, and then a target signal and an interference signal are distinguished to realize distance.

The entropy of cross-correlation (corentropy) is derived from the kernel algorithm, whose basic idea is to convert the data of two discrete signals from the input space into a high-dimensional feature vector space. The high-dimensional feature vector space is a regenerative nuclear Hilbert space, and inner product operation is selected when the Hilbert space calculates the feature vector. Fourier transform is carried out on the cross-correlation entropy, and then the cross-correlation entropy spectrum density function of the two discrete signals can be obtained. Cross-correlation entropy Spectral Density (CSD) reflects the cross-correlation entropy power Density distribution of two discrete signals in the frequency domain. If a frequency point in the CSD has an obvious spectrum peak, the cross-correlation entropy power of the two discrete signals at the frequency point is higher, and the similarity of the two discrete signals at the frequency point is higher.

The invention provides a distance method of a laser fuse in an aerosol environment, the principle of which is shown in figure 1, and the method specifically comprises the following steps:

step 1, according to the set distance R_eCalculating a reference frequency f_IFeGenerating a frequency of f_IFeCorresponding reference difference frequency signal s_IFe(t); obtaining a currently actually measured target echo actual measurement difference frequency signal s_IF(t), wherein t is the time when the difference frequency signal occurs.

Step 2, calculating an actually measured difference frequency signal s_IF(t) and a reference difference signal s_IFe(t) entropy of cross-correlationWherein m is the time offset of the two difference frequency signals; entropy of cross-correlationPerforming discrete Fourier transform to obtain cross-correlation entropy spectrum density C (2 pi f), wherein f is the frequency of the difference frequency signal; cross-correlation entropy spectrum density C (2 pi f) sequence [ C₁,C₂,…C_n]Wherein n is the maximum number of terms of the cross-correlation entropy spectral density sequence, the sum of the cross-correlation entropy spectral densities is expressed asWherein, i is the serial number of the cross-correlation entropy spectrum density, and i is 1,2 … n.

The processing mode of the invention is different from the prior art when the cross-correlation entropy spectrum density is used for signal denoising and filter design, and the prior art only counts the peak point of the entropy spectrum density.

Step 3, setting a threshold value as E_bkIf E is_IF≥E_bkThen the reference difference frequency signal s is determined_IFe(t) sum-and-calculated difference signal s_IF(t) if the similarity is high, executing step 4 to determine whether the signal is a target signal; if E_IF<E_bkThen the reference difference frequency signal s is determined_IFe(t) sum-and-calculated difference signal s_IF(t) the similarity is low, the target signal is not needed to be judged, and the step 1 is returned to restart the distance calculation.

Step 4, according to the movement speed v and the detection time interval T of the fuse_cCalculating delta R and recalculating the required fuse distance R based on delta R_eI.e. R_e＝R_eΔ R, performing step 1 and starting the next detection until a plurality of consecutive measurements (optimally, 5-6 measurements are selected), if the results satisfy E_IF≥E_bkIf the signal is a target signal and meets the distance condition, igniting the fuse and outputting an initiation signal; if the condition E is not satisfied continuously for a plurality of times_IF≥E_bkIf yes, the current echo is caused by smoke interference, and step 1 is executed to start the next detection.

In the non-aerosol (no smoke) environment, the laser echo signal is good, the signal spectrum is single, and the difference frequency signal with high resolution can be obtained by the frequency domain analysis processing method, however, in the aerosol environment with a certain concentration, the signal-to-noise ratio of the laser echo signal is reduced due to noise interference, and the distance error is caused by different frequency components appearing in the difference frequency signal spectrum, as shown in fig. 2(a) and fig. 2 (b). Aiming at the problem, the invention applies a cross-correlation entropy spectrum density CSD algorithm to process difference frequency signals. Wherein two consecutive detections are assumed at t₁And t₂The distances between the time and the target are respectively R₁And R₂And Δ R ═ R₁-R₂。

According to the principle of continuous wave laser detection, the distance R is fixed_eThe corresponding difference frequency signal is a cosine signal with a certain frequency. If the echo difference frequency signal of the fuse is similar to the reference difference frequency signal, the main frequency component of the current difference frequency signal is considered to be consistent with the frequency of the reference difference frequency signal, and therefore the distance between the target and the fuse at the moment is determined to be equal to the fixed distance R_e. If the similarity of the two signals does not exceed the threshold, the interference component proportion in the difference frequency signal at the moment is considered to be large, or the difference between the center frequency of the difference frequency signal and the reference target distance frequency is considered to be large, so that the distance condition is not met. The fuze is continuously arranged at a plurality of moments t in the process of approaching the bullet eyes₁,t₂,…,t_nDetecting the target for multiple times, and judging whether the target signal is at a fixed distance R according to the result of multiple cross-correlation entropy spectrum density analysis on the difference frequency signal_eAnd in the accepted error range, false target signals generated by smoke interference are removed, so that false alarms are avoided, and the reliability of fixed distance is improved.

As shown in the processing results of fig. 3(a) - (c), it can be found that, as the visibility of smoke decreases, the distance target of fig. 3(a) is 3m, the distance to smoke is 1m, the distance to distance is 3m, and the visibility is 10m, the distance target of fig. 3(b) is 5m, the distance to smoke is 3m, the distance to distance is 5m, and the visibility is 10m, and the distance target of fig. 3(c) is 9m, the distance to smoke is 7m, the distance to distance is 9m, and the visibility is 10m, the distance frequency f in the processing results of the CSD algorithm decreases as the visibility of smoke decreases_IFeThe spectrum peak amplitude is gradually reduced, which shows that smoke interference causes the proportion of the target signal in the difference frequency signal to be continuously reduced, the difference between the measured difference frequency signal and the ideal difference frequency signal is enhanced, and the cross-correlation entropy is reduced, so that the spectrum peak amplitude in the spectrum density distribution of the cross-correlation entropy is reduced. Ranging frequency f in CSD algorithm result when distance between target and fuze is equal to ranging distance_IFeThe influence of smoke interference is suppressed, which shows that each frequency and f in the smoke interference signal_IFeThe difference is large, and the frequencies are not f due to the characteristic of Gaussian kernel function in cross-correlation entropy calculation_IFeThe interference signal is attenuated quickly when the cross-correlation entropy is calculated, thereby inhibiting the influence of smoke interference and keeping the frequency as the target f_IFeAccording to the target signal of (f) after CSD processing_IFeThe size can realize spacing.

In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.