KR20170000835A - FMCW proximity fuse and Shell height detecting methods that prevent shell from wrong explosion - Google Patents

Abstract

Disclosed are a fuse with an FMCW proximity sensor and a method to detect the shell altitude using the same. The present invention relates to an intelligent technology for detecting the shell altitude, which can effectively deal with an error in detection by a proximity sensor, and performs the following method to detect the altitude based on a proximity sensor antenna (14) with the FMCW method, which has an antenna placement and fixation structure which is proper for the flight characteristics of a shell and the structure of a fuse, and a signal processor unit (17). The method of the present invention comprises: a step of performing fast Fourier transform (FFT) on x(n), which is N pieces of time area sampling data among IF signals with Doppler effects removed, into X(k), which is input data of one channel of the real part of a frequency area, to perform FFT of the X(k), to obtain the absolute value, and to obtain the spectrum waveform; a step of saving the maximum peak value of each section among the spectrum waveform, which has no fire altitude signal for a certain unit time in the spectrum waveform, as the threshold; and a step of comparing the current spectrum waveform, which is being calculated, and the threshold to determine the maximum peak value, which is the threshold or higher, as the effective beat frequency value at the time point, and to convert it into an effective altitude value. Here, the method can obtain a filtered effective altitude by further applying the Kalman filter for removing the noise. Accordingly, the present invention can realize a small-sized, lightweight, intelligent FMCW proximity sensor which can be mounted on a variety of projectiles, and can provide a high-performance proximity explosive shell which prevents a mistaken fire due to a momentary inflow of a detection signal in a variety of battlefield environments both on the ground and at sea.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a height of a shell using an FMCW proximity sensor,

This invention relates to intelligent cannon altitude detection techniques that are configured to effectively respond to detection errors of proximity sensors that may occur at times in the flight of a cannon in a shell of a shell designed to explode at a certain altitude above a target point.

Proximity sensor using FMCW (frequency modulated continuous wave) transmission / reception method can measure the relative distance between the sensor and the reflective object by measuring the frequency difference between the radio waves radiated from the antenna and the reflected wave from the feature It is widely used for various purposes such as obstacle detectors and speedometers.

FMCW proximity sensor is difficult to measure the azimuth angle of the target in case of a simple configuration that uses a single antenna for transmission and reception but shows relatively good accuracy in measuring the distance from the target. When using a microwave of several to several tens of GHz, Since the whole device can be made compact, lightweight, and low in power and has excellent durability, it is also actively utilized as a small proximity sensor mounted on a shell tube.

The proximity fuse, which is equipped with the above-described proximity sensor, includes a cluster bomb for heavy suppression of the enemy, an aircraft interceptor for the aircraft interceptor, a hammer shell for flying the low direct trajectory on the sea surface, It can be used to detonate the shells of many types of aerial explosives, such as small-caliber ruptures, of all kinds intended to effect shots rather than penetration effects.

The proximity sensor mounted on the new pipe serves as a large target detection such as an explosion altitude detection or enemy ship, and usually generates an aerial signal under the condition that the altitude of the pre-injection set altitude matches the altitude detected near the impact point Explode the shell.

At this time, the explosion altitude at which the near fuse responds is the relative distance between the sensor antenna and the feature reflecting the radio wave, not the absolute altitude from the sea level. Only the detection of the relative distance value satisfies the set explosion altitude value The identity, azimuth, and relative velocity information of the detected object are usually ignored.

In other words, when an unexpected obstacle appears on the flight path, the proximity sensor recognizes the obstacle as a feature and sends out a false detection signal, which means that the fuse may malfunction against the mission purpose.

In recent years, there is a risk of malfunction of the proximity sensor that is mounted in the development of a range extension gun (mainly an air explosion type cluster shot) that descends at a high altitude and induces a long distance at a low altitude.

Therefore, in order for the explosive to perform its intended mission perfectly, it is necessary to set the explosion altitude above the target point not only uniformly in the charging process but also the trajectory to the explosion point, the terrain near the explosion point, (Cliffs, valleys, waves, large vessels, airplanes, etc.) that can be encountered during the course of the attack.

(1) Japanese Unexamined Patent Publication No. 8-005300 Active proximity fuse (2) Japanese Patent Laid Open No. 8-110200 Active proximity fuse (3) US registered patent US 6,741,202 Three-dimensional synthetic aperture radar operating method (4) US registered patent US 7,453,392 Doppler radar system and method for fuzzing (5) Korea registered patent KR 1239166 FMCW proximity sensor

The technical object of the present invention is to implement an FMCW signal processing apparatus and signal processing method capable of quickly and accurately detecting the current altitude of a shell without error.

More specifically, it is an object of the present invention to provide various sensing information (including many suddenly varying noises) received by the proximity sensor so as not to cause a false operation by an unexpected proximity obstacle before reaching a target point in a state that the shell is flying at high speed And to implement a high-performance FMCW proximity sensor for intelligent signal processing based on reliability measurement.

To this end, an FMCW proximity sensor based on an FMCW proximity sensor antenna 14 disposed in a body of a cannon tube, an inner space of a nose cone, and an FMCW signal processing unit 17 disposed thereunder is presented as concrete operating means.

The FMCW proximity sensor antenna 14 has an antenna arrangement structure suitable for a flight characteristic of a cannon and a structure of a new pipe, a rigid antenna supporting and fixing structure, and an efficient radio wave radiation pattern, An effective altitude value which is sufficiently reliable by the FMCW signal processing unit 17 performing the processing step is calculated as an aerial signal.

Next, the effective altitude signal of the present invention as a concrete method means differentiating from the conventional art is obtained through the following processing steps.

First, the instantaneous detection step of obtaining the real time detection value reflecting the influence of the feature that suddenly appears on the flight orbit in the form of a digital signal capable of high-speed processing is performed in the following first to fourth steps. If you look briefly at each step,

A first step of fast Fourier transforming the N time-domain sampling data x (n) out of the IF signals from which the Doppler effect has been removed and transforming them into frequency domain data X (k)

A second step of applying a Hanning window function to the sampling data to suppress spectrum leakage of the data X (k)

A third step of fast Fourier transforming real (real part) real number 1 channel data X (k) to which the Hanning window function is applied, and calculating an absolute value therefrom to obtain a spectral waveform;

A fourth step of detecting a bit frequency signal of a valid size in the spectral waveform obtained as described above and converting it into an instantaneous altitude value.

Next, an effective altitude detection step for filtering undesired detection error information that has been input to the detected instantaneous altitude value is performed in the following fifth through seventh steps. If you look briefly at each step,

The fifth step of storing the maximum peak value of each of the spectral waveforms having no signal satisfying the explosion height for a predetermined unit time (U) of one block in the spectral waveform obtained in the third step as a threshold value of the block step,

Then, the current spectral waveform being calculated through the third step is compared with the threshold values obtained through the fifth step, and the maximum value, that is, the maximum peak value among the peak values not less than the threshold value, And the seventh step of conversion to the effective altitude value.

In this case, the sixth step of filtering the maximum peak value by the Kalman filter using the filter coefficient determined in consideration of the altitude change rate according to the falling speed may be applied to the seventh step.

In the following, the basic structure of the above-described FMCW proximity sensor and specific details supporting the FMCW signal processing step are further added.

According to the present invention, it is possible to realize an FMCW proximity sensor for detecting the height of a shell having small durability and reliability, which is small and light enough to be mounted on a variety of guns, and an extended configuration thereof. Value can be reflected meaningfully to the currently detected signal value.

Accordingly, it is possible to effectively filter out an abnormal detection signal due to an instantaneous sensor error or the like in various electric field environments including both the ground and the sea, thereby providing a high-performance proximity explosive shell in which unexpected operation of the pentagon is prevented.

FIGS. 1A and 1B are an exploded view showing the antenna installation structure in the FMCW proximity fuse of the present invention, respectively, and a graph showing the radiation pattern of the antenna by electric field intensity.
FIG. 2 is a flowchart illustrating a method of processing an FMCW signal according to the present invention. FIG.
3 is a graph showing an FMCW modulation waveform when the Doppler effect is present and an IF signal from which the FMCW modulation waveform is removed.
4 illustrates an IF signal sampling interval of the present invention.
5A is an example of application of the Hanning window function for suppressing spectral leakage used in the present invention.
FIG. 5B is a view showing an example where a valid bit frequency signal is detected after sampling data subjected to a window function is subjected to real part FFT to obtain a spectral waveform.
6 is a graph illustrating a threshold value determination process for determining an effective bit frequency.
7 is a graph showing a filtering effective altitude using a Kalman filter.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: FIG.

However, in the embodiments described below, the components expressed in the specific terminology and the combination structure thereof do not limit the technical idea that is included in the present invention in a comprehensive manner.

1 is an exploded perspective view illustrating an antenna installation part of an FMCW proximity fuse of the present invention and an antenna radiation pattern according to the present invention.

The FMCW proximity sensor antenna 14 (which includes all of the reference numeral 14-n) is disposed at the forefront of the main body 10 and is disposed on the front side of the main body 10 facing the antenna, that is, The nose cone 11 made of a material having a low dielectric constant such as a polymer resin is covered.

The installation structure of the FMCW proximity sensor will be described in detail with reference to FIG. 1A.

A disk-shaped bottom plate 13-4 is fixedly disposed in the inner space of the nose cone 11, and an FMCW proximity sensor antenna 14 is disposed on the bottom plate 13-4. A filler A fixing form 12 may be filled.

The FMCW proximity sensor antenna 14 includes a standing plate 14-4 in the form of a trapezoidal plate vertically erected on a bottom plate 13-4 and a proximity sensor 14-4 formed on one surface of the standing plate 14-4. The antenna feed part 14-1 and the proximity sensor antenna mutual coupling part 14-2 formed on the opposite surface of the standing plate 14-4 and the antenna 2 attached to the left and right edges of the standing plate 12, And a plurality of proximity sensor antenna pawls 14-3.

The proximity sensor antenna 14, which operates at a frequency of several to several tens GHz, is formed on the basis of a standing plate 14-4 that extends in the z-axis + direction (upward in the drawing) through the center point of the bottom plate. The standing plate is formed in a trapezoidal plate shape becoming narrower toward the upper side, and is set to be perpendicular to the telemetry antenna pole 13-2 when viewed from above.

The proximity sensor antenna pawl 14-3 connected to the proximity sensor antenna feed portion 14-1 is attached to the right and left corners of the standing plate 12 at an oblique angle. In detail, the proximity sensor antenna pawls 14-3 may be shorter than the telemetry antenna pawls 13-3 and supported and fixed in the left and right corners of the standing plate 14-4 .

The above-described proximity sensor antenna is conceptually a dipole antenna bent in accordance with the nozzone space, having a mutual coupling type feed structure and a micro-strip line structure.

In the above configuration, the two proximity sensor antenna pawls 14-3 are supported and fixed at the same angle as the right and left corner inclination angles of the standing plate 14-4, so that the distance from the isotropic antenna is 5dBi So that the radiation gain is secured.

The proximity sensor antenna configuration described above can be configured not only by the new pipe body 11 distinguished as the new pipe but also by forming the nozzone in the foam body having the aerial structure other than the detachable fuse pipe Leave. In other words, it should be noted that the scope of application of the present invention is not limited to a fuse, but can be applied to an expanding concept extending to a fusing body.

Whether the antenna space of a desired wavelength band can be ensured in the nosecone is a matter which should be considered as the most basic consideration in designing the antenna for the proximity sensor. However, the antenna once installed has the tangential acceleration due to the sudden impact shock, It is also important that it is fully fixed and supported so that it can overcome the back and work normally until just before the explosion.

As shown in FIG. 1B, an antenna beam having a radiation pattern formed in a forward direction (a flying direction) of the shell is an antenna beam for a proximity sensor, and the telemetry antenna pole 13-2 shown in the figure and the ground A radiation pattern is formed in the back (opposite direction of the flight) of the shell so as to facilitate communication with the observation point and not obstruct the proximity sensor antenna 14 .

Below the bottom plate 13-4 is disposed an ignition part 18 which is detonated by the FMCW signal processing part 17 and the altitude detection signal calculated by the FMCW signal processing part 17, It is electronically programmed to perform the altitude detection method described below.

For reference, the z-axis direction is the flight direction of the shell and the upper side of the body of the new tube, and the -direction of the z-axis means the rear side of the center axis of the shell. Accordingly, in the proximity sensor antenna 14 of FIG. 1A, the standing plate 14-4 is a plane perpendicular to the Y axis and the proximity sensor antenna pole 14-3 is arranged in the positive and negative directions of the X axis, The pattern measurement graph is measured by the X, Y, and Z axis direction reference. As a whole, it can be seen that the transmission strength of a sufficient FMCW radio wave is secured in the range of the conical angle of 120 ° around the direction of the flight of the shell. This is a beam pattern that can cover all the ammunition falling slowly at an angle of about 5 ° to 20 ° to the sea and most of the night sky falling at an angle of about 30 ° to 45 ° from the ground. (Noise) in which the relative distance (shell altitude) information of the reflected wave changes instantaneously due to the terrain of the valley or the local wave of the sea level, except for the shell which falls almost vertically like glass or mortar shell, Structure.

Next, a method of detecting the altitude of the cannon for transmitting / receiving the radio wave by the FMCW method based on the above-mentioned FMCW proximity sensor and detecting the relative altitude with respect to the target or the terrain at the receiving time (hereinafter referred to as "altitude" for convenience) will be described.

The instantaneous detection step of obtaining the real-time detection value reflecting the effect of the feature that suddenly appears on the flight orbit in the form of a digital signal capable of high-speed processing is performed in the following first to fourth steps. The basic process common to the signal processing technology of the existing proximity sensor is the first step.

First, the RF signal is linearly frequency-modulated (FM) by a desired bandwidth and transmitted in the form of a continuous wave (CW), and the RF signal reflected from the target or the terrain is received.

Since the received RF signal has a time delay as compared with the transmission, the frequency difference is proportional to the distance. By acquiring the IF signal (intermediate frequency) containing the distance information from the reflection surface (target or terrain) by demodulating it into the original signal.

The altitude detection method of the present invention, which is a combination of high-speed data processing and comparison based on interval comparison and noise filtering, is illustrated in FIG.

)를 검출하고 이로부터 현재시점에 탐지된 순간고도를 계산하는 과정 까지를 보여준다.3 to 5 illustrate the beat frequency (IF) signal by sampling and signal processing the IF signal,

And the process of calculating the instantaneous altitude detected at the present time from this is shown.

That is, as described above, the altitude value described on the basis of FIGS. 3 to 5 is the instantaneous altitude value that does not filter the instantaneous rapid change (noise) of the altitude value that can occur according to the surrounding situation.

3 shows an FMCW modulation waveform when there is a Doppler effect.

The RF signal received from the existing proximity sensor can be used to obtain the relative speed information by using the Doppler effect due to the difference of the speed of the shell, that is, the relative speed between the RF transmission radar and the stationary feature, . However, in the present invention, the Doppler effect is intentionally removed to obtain the IF signal from which the relative speed information is removed, and then the bit frequency is detected from the IF signal to obtain the altitude value.

Referring to FIG. 3, when approaching, the Doppler frequency increases by Fd, and when the Doppler frequency moves away, it becomes lower by Fd. Usually, guided weapons such as guided missiles are important information detected by radar sensors, and they are often used as speed information by using this frequency deviation phenomenon itself.

However, as in the present invention, it is necessary to eliminate (or minimize) the Doppler effect (frequency shift) as described above in a proximity sensor in which it is important to accurately detect and fire the explosion altitude set before the launching rather than the speed of the shell.

: 아래첨자 t는 특정 시간영역에서의 값을 의미)와 고도관계를 구할 수 있다.In this case, when the increase and decrease of the frequency is a constant linear FMCW, that is, an FMCW signal appearing as a sawtooth wave on the frequency graph,

: The subscript t means the value in a specific time domain) and an elevation relationship.

은 변조폭(주파수변화시간), F_up은 목표물(또는 지형)에 접근할 때의 RF반사신호의 주파수증가, F_dn은 목표물(또는 지형)에서 멀어질 때의 RF반사신호의 주파수감소, C는 전파속도(광속)이며 R은 도 3의 Rx(빨간선)에서 도플러효과가 제거된 비트주파수

(점선으로 표시된 IF frequency값)이다.In the above equation, BW is the bandwidth (frequency width) of the sensor transmission wave,

F_up is the frequency increase of the RF reflection signal when approaching the target (or terrain), F_dn is the frequency reduction of the RF reflection signal when the target is away from the target (or terrain), C is the propagation (Light flux) and R is the bit frequency at which the Doppler effect is removed from Rx (red line)

(The IF frequency value indicated by the dotted line).

(비트주파수)값은 도 3 아래에서 점선으로 표시되는 구간의 Y축 값인데 보통 포탄 근접센서에서 송출후 수신되는 반사파는 접근파가 많으므로, 도플러효과가 제거된 비트주파수는 그래프상에서 보통 빨간색 점선의 Y축 값이 된다. 아래의 이산신호변환을 거치지 않을 때는 이 값이 RF신호의 BW값에 대응되는 고도값으로 환산된다.this

(Bit frequency) value is the Y-axis value of the section indicated by a dotted line in FIG. 3, and since the reflected wave received after being transmitted from the shell proximity sensor has many approach waves, the bit frequency from which the Doppler effect is removed is represented by a normal red dotted line Axis direction. When the following discrete signal conversion is not performed, this value is converted into an altitude value corresponding to the BW value of the RF signal.

For reference, in order to obtain the R value, it is necessary to first determine a section for effectively sampling the IF signal.

4 illustrates an effective sampling interval for sampling an IF signal from which a Doppler effect has been removed. (The sampling period is not referred to as a sawtooth wave in the figure.) In the present invention, Sampling is performed in the remaining linear sections except for the beginning and end of the rising / falling section where the linear change is not made in the rising and falling sections.

/2이고 이에 따라 샘플링 주파수 및 포인트를 결정할 수 있다.Typical frequency modulation is based on a sawtooth modulation period in which the rising and falling of the modulation period is repeated linearly and continuously. Also in the present invention, a linear rising / falling frequency modulation method having no flat section is adopted as shown in FIG. Therefore, the rising section time and the falling section time are half of the modulation period

/ 2 and thus the sampling frequency and the point can be determined.

Next, in order to effectively detect the bit frequency from the sampled IF signal, an FFT (Fast Fourier Transform) process, which is useful in digital signal processing, is performed to convert the IF sampling data of the time domain concept into real data of the frequency domain concept, Into a time signal X (k).

의 간격으로 표본화 한 신호가 이산시간신호 X(k)이며 이를 위해 이산푸리에변환이 필요하다. 본 발명에서는 신관의 신호처리부(17)가 이를 빠르게 실행하기 위해 고속푸리에 변환으로 수행한다. 여기까지의 처리과정은 전형적인 디지털 신호처리의 단계라 할 수 있으며 본 발명에서는 제1단계에 해당한다.As is known, the IF signal, which is a continuous-time signal, is converted into a modulation width (sampling period)

And the discrete Fourier transform is necessary for this. In the present invention, the signal processing unit 17 of the new pipe performs fast Fourier transform to perform it quickly. The process up to this point is a typical digital signal processing step, and corresponds to the first step in the present invention.

At this time, there may be spectral leakage that may occur after the fast Fourier transform.

를 적용할 수 있다. The Fourier transform is based on the premise that for practical processing of infinite signals, the spectrum is not greatly affected in the integration process, and the spectrum is leaked when there is a sudden cut. To reduce this, a soft data window

Can be applied.

In other words, a Hann window function (Raised cosine) can be applied to the IF sampling data of the time domain concept. The formula for applying the function is as follows.

Hanning window reduces spectral leakage and significantly reduces the wave appearing in the spectrum. This process corresponds to the second step in the present invention.

4A is a diagram illustrating an example of a Hanning window function application for suppressing spectral leakage.

In the present invention, the Fast Fourier Transform is a step of FFT-transforming N time-domain sampling data x (k) in one channel of the real part and transforming it into input data X (k) in the frequency domain. The conversion equation is as follows.

FIG. 4B shows a spectrum waveform obtained by performing a real part FFT on the frequency-domain sampling data X (k) applied with the Hanning window function as shown in FIG. 4A. Since the input data is one channel of the real part, the fast Fourier transform of the real part is performed according to the above equation, and the absolute value (magnitude) is calculated therefrom to obtain the spectrum waveform. (This is the process of the third step.)

Through the above steps, it is possible to detect a bit frequency signal of a valid size in the spectrum waveform in the IF sampled signal, and obtain the instantaneous altitude value without removing the speed information by obtaining the difference between the transmission and reception signals. (This is the processing procedure of the fourth step.)

: 아래첨자 r은 이산시간 영역에서의 실수(real)값을 의미)를 구하기 위해 앞서 제시한 식을 재차 이용한다.At this time,

: The subscript r is the real value in the discrete time domain).

Through the steps described above, instantaneous elevation values that can be processed very quickly and simply in a small processor of the new building, while retaining sophisticated detection values, were obtained.

It is now necessary to extract an effective altitude value suitable for the actual environment of the shell so as to be practically applicable to the detonation motion of the fuse among the altitude values at this moment.

이 시간영역의 신호라면 이산신호 변환을 거쳐 얻어지는

은 이산시간영역의 실수값(스펙트럼 파형)이다. 이 같은 실수형태의 비트주파수 값을 이용하면 아래와 서술한 바와 같이 이전 시간과 현재 시간에 얻어지는 비트주파수들을 서로 비교하는 논리회로의 설계가 매우 쉬워지며 그 처리속도 또한 빨라진다.For reference, the bit frequency

If the signal is in the time domain,

(Spectral waveform) of the discrete time domain. Using such a real bit-frequency value makes it very easy to design a logic circuit that compares the bit frequencies obtained at the previous time and the current time as described below, and the processing speed is also improved.

Next, an effective altitude detection step for filtering undesired detection error information that has been input to the detected instantaneous altitude value is performed in the following fifth through seventh steps. Let's look at each step briefly.

In order to logically determine the validity of the instantaneous elevation values obtained at the bit frequency by an accumulated comparison, the following threshold value concept can be stored.

The term " threshold " means a threshold value that satisfies a condition under which an operation is started.

In the present invention, the maximum peak value of each of the spectral waveforms having no signal satisfying the explosion height for a predetermined unit time (U) of one block in the spectral waveform obtained in the third step is stored as a threshold value of the block .

In the embodiment of FIG. 6, for convenience of description, the unit time is set to 1 second, and the spectral waveform for 1 second is calculated. And the maximum value among them is set as a threshold value. In this case, the ability to respond to the instantaneous obstacles (valley topography, mast of adjacent ships, nearby objects, etc.) described in the background description and the solution is greatly increased.

When the shell is stably flying at a high altitude, the noise signal of the signal processing system appears without an effective altitude signal in the proximity sensor of the new pipe. In this case, the spectral waveform for a unit time (for example, 1 second) To find the maximum value. It has the same function as Maxhold (maximum value) of the spectrum analyzer, and the cumulative spectrum is, for example, the target altitude (relative altitude relative to the target terrain: HOB) + 2m, + 3dB is used as the threshold value. (This is the process of the fifth step.)

FIG. 6 is a graph illustrating a threshold waveform at the time of effective altitude detection, and is a diagram illustrating the fifth and seventh steps.

As a method for distinguishing noise from altitude information effective at an instantaneous altitude value including undesired sudden change values (noise) obtained through signal processing in the first to fourth steps, a bit frequency obtained through a spectral waveform, that is, ) This shows how to effectively filter out instantaneous sudden changes that occur at an instant altitude value due to external factors.

Referring to FIG. 6, a threshold value is calculated with one second as one block, and a threshold value obtained from n-2 to n-1 second intervals at the nth detection of the altitude is compared with a current spectral waveform, That is, the maximum peak value, is determined to be the bit value for converting the effective altitude value per section (block), and is stored

In other words, the spectral waveform of the previous time without the explosion altitude (mission altitude) signal is stored as a threshold value (or threshold value) and compared with the current spectral waveform. In the case of the altitude 20 m, If the signal is not within the range of 7m to 9m, the current altitude is still considered to be the previous threshold of 20m. In this case, it is possible to effectively filter the momentary obstacles on the ground, which are detected between 9m and 20m, or the omnipresence signal due to the transient wave in the sea, in the terminal induction phase of the low level horizontal flying shell.

For reference, the predetermined section (one block) shown in FIG. 6 is 1 second, but it can be appropriately adjusted as necessary, and the adjustment standard is set based on the speed and descent angle of the shell (a factor affecting the rate of change in altitude) The altitude (the probability of occurrence of the noise of the maximum peak value), and the amount of rotation of the shell (the phase difference of the transmission and reception waves).

Meanwhile, in the altitude detection method of the present invention, a step of excluding a noise altitude value deviating from a predicted trend may be additionally performed.

This is in fact taking into account the fact that the height of the shell is physically difficult to change rapidly during the flight of the shell and changes along the course of the terrain.

For this, a Kalman filter was applied to the altitude value determined as the maximum peak value above the threshold value. (Corresponds to the sixth step).

The relation of the Kalman filter is as follows.

The Kalman filter reflects the prediction and measurement noise as a normal distribution, reflecting the dynamics of the target data. Many scientific experimental models can be accessed comprehensively by verifying probabilities and risks through Kalman filtering backtester.

The Kalman filter, which tracks the optimal value through iterative operations, is based on measurements made over time, as a recursive filter that tracks the state of the linear dynamics including noise.

은 현 시점 측정값

에 표준편차계수

를 곱한 값과 이전 단계의 필터링된 3개의 값들을 각각의 표준편차계수

과 곱한 값을 합해서 구하고 있음을 알 수 있다.Referring to the relationship, the value obtained through the filter

Lt; RTI ID = 0.0 >

Standard deviation coefficient

And the filtered three values of the previous step are multiplied by respective standard deviation coefficients

And the sum of the values obtained by multiplying the values obtained by the multiplication.

It is most preferable to determine the standard deviation coefficient of the Kalman filter in consideration of the altitude change rate according to the dropping rate, and the number of input data is the same as the previous altitude value comparing step, , The average flight height of the shell (noise generation rate), and the amount of shell rotation (the phase difference of the transmission and reception waves) of the shell.

After the Kalman filtering step, the current spectral waveform being calculated through the third step is compared with the threshold values obtained through the fifth step, and the maximum peak value is set as the effective bit frequency value at that point, and the filtered effective altitude value In the second step.

That is, the filtered effective altitude value in the present embodiment is obtained by a total of four pieces of data including the filter valid altitude value of the previous three times and the current effective altitude value. Considering that the above-described altitude value for each interval is obtained through comparison of the threshold values of the three previous spectral waveforms, it can be seen that the three-sample maximum value comparison and the four-sample standard deviation comparison are applied in this embodiment.

Obviously, as the number of data increases, the filtered effective altitude change becomes insensitive and more sensitive as the number of data increases.

7 is an effective altitude (filtered) obtained through the sixth and seventh steps. In the drawing, the blue graph shows the altitude value detected by the FMCW signal processing step, the red graph shows the effective altitude value obtained through the Kalman filter, and the filtered effective altitude shows an improved result when the detection altitude shows an unusual value .

The technical idea of the present invention has been described above with reference to specific embodiments. It should be understood that the technical idea of the present invention should be construed on the basis of the contents described in the following claims rather than the technical interpretation category of the embodiment.

10: New body body
11: Nozokon
12: Filler
13-3: Telemetry antenna pole
13-4: (for telemetry antenna ground) Bottom plate
14: Proximity sensor antenna
14-1:
14-2:
14-3: Proximity sensor antenna pole
14-4: standing plate
17:
18: Explosion

Claims (7)

A first step of fast Fourier transforming the N time-domain sampling data x (n) out of the IF signals from which the Doppler effect has been removed and transforming them into frequency domain data X (k);
A third step of subjecting the data X (k) to real-valued fast Fourier transform to obtain an absolute value and obtaining a spectral waveform therefrom;
A fourth step of detecting a bit frequency signal of a valid size in the spectrum waveform and converting it into an instantaneous altitude value;
A fifth step of storing, as a threshold value of the block, a peak-to-peak maximum peak value of a spectral waveform having no signal satisfying an explosion altitude for a predetermined unit time (U) of one block in the spectral waveform;
The current spectral waveform being calculated through the third step is compared with the stored threshold values by the block through the fifth step, and the maximum peak value of the threshold value or more is determined as the effective bit frequency value at that time point and converted to the effective altitude value A method for detecting a height of a shell of an FMCW proximity sensor, the method comprising: The method according to claim 1,
The predetermined unit time (U) is adjusted according to the current speed and descent angle of the shell and the average flying height per unit time,
And comparing the threshold values obtained in the n-2 to n-1 sec intervals when the unit time is 1 second with the current spectral waveform, and setting a maximum value of the peak values equal to or higher than the threshold value as a threshold value of the n-th block. A method for detecting the height of a shell of an FMCW proximity sensor. 3. The method of claim 2,
And a second step of applying a Hanning window function to the data X (k) to suppress spectral leakage between the first step and the third step. The method of claim 3,
And a sixth step of filtering the maximum peak value between the fifth step and the seventh step with a Kalman filter using a filter coefficient determined in consideration of a rate of altitude change according to a falling rate of the shell, Of the shell height detection method. A main pipe body (10);
Permeable nose cone (11) coupled to the upper end of the body (10);
A disk-shaped bottom plate (13-4) arranged and fixed in an inner space of the nosecone (11);
An FMCW proximity sensor antenna 14 mounted on the bottom plate 13-4;
An FMCW signal processing unit 17 installed below the bottom plate 13-4;
And a detonator 18 which is detonated by the altitude detection signal calculated by the FMCW signal processor,
The FMCW signal processing unit 17,
An FMCW proximity sensor mounted fuse, characterized in that the altitude detection method according to any one of claims 1 to 4 is carried out. 6. The method of claim 5,
The FMCW proximity sensor antenna 14 includes an upright plate 14-4 in the form of a trapezoidal plate vertically erected on the bottom plate 13-4 and an upright plate 14-4 formed on one surface of the upstand plate 14-4 A proximal sensor antenna feed part 14-1 and a proximity sensor antenna mutual coupling part 14-2 formed on a surface opposite to the standing plate 14-4; And two proximity sensor antenna pawls 14-3,
The two proximity sensor antenna pawls 14-3 are supported and fixed at the same angle as the right and left corner inclination angles of the standing plate 14-4 so that the radiation gain of 5 dBi to the isotropic antenna The FMCW proximity sensor is mounted on the main body of the vehicle. A main pipe body (10);
Permeable nose cone (11) coupled to the upper end of the body (10);
A disk-shaped bottom plate (13-4) arranged and fixed in an inner space of the nosecone (11);
An FMCW proximity sensor antenna 14 mounted on the bottom plate 13-4;
An FMCW signal processing unit 17 installed below the bottom plate 13-4;
And an ignition unit (18) that is ignited by the altitude detection signal calculated by the FMCW signal processing unit (17)
The FMCW signal processing unit 17,
A spreader characterized by carrying out the altitude detection method according to any one of claims 1 to 4.

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