RU2285272C1 - Method for determining position of a rifleman in an area - Google Patents

Abstract

FIELD: measuring equipment engineering, in particular, technology for detecting position of an object using sound waves, in particular, for determining position of rifleman in an area.

SUBSTANCE: in accordance to method, recording of sound signals is enabled in case of registration of impact waves from by-flying ultrasound bullet and barrel wave from expanding gases from barrel edge by sensitive elements, processing of these signals by means of processor, on basis of results of which position of sound source is determined. Method contains following innovations: sensitive elements are preliminarily fastened immovably relatively to optical axis of video recording device, synchronously with recording of sound signal by not less than 3 sensitive elements, recording of video image of possible position of sound source is performed by means of at least one video recording device, mounted with possible change of filming direction and position in space, during following processing of signals moment of arrival of barrel wave and frame from recorded video row, closest to aforementioned moment, are combined, and mark of rifleman position is placed on that frame. Recording of video image is performed in optical or infrasound or other range.

EFFECT: improved safety, possible finding of direction towards position of an enemy, possible determining of distance to enemy by creating a method making it possible not only to determine direction towards sound source, but also to detect ("see") it.

2 cl, 6 dwg

Description

Technical field

The invention relates to measuring technique, in particular to determining the location of an object using sound waves, in particular the location of the shooter on the ground.

State of the art

Currently, methods for determining the trajectory of a supersonic artillery shell are quite well developed. To a lesser extent, methods have been developed for direction finding of firing positions of snipers. Therefore, much attention is paid to the development of methods for determining the location of a shooter on the ground and search systems for snipers that will find application in law enforcement agencies, in the army, etc.

A known method for determining the trajectory of a supersonic projectile described in the patent for the invention of the "Acoustic system" counter-sniper "[1], designed to determine the movement of a supersonic projectile and includes recording shock waves and compression waves, at least two sensing elements with known mutual location, converting the collected information into an information signal of a time series, processing these signals using a processor, which takes into account the arrival time and amplitude of the state of shock waves from each sensitive element, they are classified as possible components of a blast wave, shock wave, or neither of them, and based on the ballistic coefficient of a supersonic projectile as a function of amplitude voltage (Vp) and wave slope N (V / T) taken from information about the time series and the relative time of arrival of the shock wave, they judge the assumed trajectory of the supersonic projectile.

This method, despite the complexity, laboriousness and significant capital costs for creating the system allows the registration of sound waves that occur during the propagation of an object moving at supersonic speed and determine its trajectory.

The disadvantages of the above method include the need for a terrain orientation system and the inability to obtain a sound image of objects.

From optics it is known that image quality depends on the wavelength. According to the Rayleigh criterion, images of two close luminous (incoherent) points can also be considered separate if the center of the diffraction spot corresponding to one point coincides with the first diffraction minimum at the second point. In accordance with the Rayleigh criterion, the smallest angular resolution δφ between remote point sources, the images of which can still be considered separate, is equal to:

In general, in geometrical optics, it is believed that the usual two-dimensional image can be obtained only if the lens diameter is d≫λ. In this case, the diffraction effects are negligible, and therefore, the wave nature of the light can be neglected. In acoustics, as a rule, we are dealing with fairly long waves. For example, a sound wave with a frequency of 1 KHz has a wavelength of about 34 cm. If you try to create some device with a resolution of 1 °, which would allow you to get a sound image using sound waves with a frequency of 1 KHz, then a simple calculation shows that the diameter of the acoustic lens or mirrors should be about 24 meters. For this reason, the usual way to build a sound image is practically impossible. Only for ultrasound, in which the wavelength is less than 2 cm, at present, it has been possible to create devices of acceptable sizes that form an audio image. The disadvantage of ultrasound is that in a normal atmosphere, ultrasonic waves decay at distances of the order of several tens of meters. In this regard, ultrasound was mainly used only in dense environments, such as water, where it damps more slowly. Sound waves in the range of 100-10000 Hz can propagate in the atmosphere over long distances, but because of the long wavelength, they are difficult to use like optical waves to obtain an image of a sound source. But it is precisely these sound waves that in most cases are an integral attribute of battle. Enemy shots, explosions, etc. are the source of these sounds, which rarely merge together. Even when firing in bursts, the interval between shots is about 0.1 seconds, which is many times longer than the duration of the shot itself. In particular, low-frequency sound waves are already used for direction finding of firing positions in a number of foreign systems, for example, "Pilar" (France) [2]. But such systems, as a rule, are rather cumbersome and require considerable time for deployment.

Therefore, it seems tempting to use these sounds not only for direction finding of firing positions of snipers, but also for obtaining their image.

In relation to this problem, if by registration of shock waves and compression waves we mean shock waves from a passing supersonic bullet and a muzzle wave from expanding gases from a barrel cut by sensitive elements, then the method for determining the trajectory of a supersonic projectile described in the patent for the invention “Acoustic system "counter-sniper" [1]), as the closest in technical essence, can be chosen as a prototype.

The disadvantages of the above prototype method include its unacceptability for determining the location of a sniper on the ground in motion and the inability to obtain a sound image of a moving object.

Disclosure of invention

The technical result achieved by the invention is to ensure security, the ability to indicate the direction of the enemy, the range to him by creating a method that allows not only to determine the direction of the sound source, but also to detect ("see") it.

The specified technical result in the claimed invention is achieved by the fact that in the method of determining the location of the shooter on the ground, which includes recording sound signals when registering shock waves from a passing supersonic bullet and a muzzle wave from expanding gases from a barrel cut by sensitive elements, processing these signals using a processor the results of which judge the location of the sound source, new is that previously sensitive elements are fixed motionless relatively optically the axis of the video recorder, simultaneously with the recording of sound signals when registering shock waves with at least 3 sensing elements, record a video image of the probable location of the sound source using at least one video recorder installed with the ability to change the shooting direction and position in space , and during subsequent processing of the signals, the moment of arrival of the muzzle wave and the frame closest in time to this moment from the recorded video sequence, to which and carry a mark on the location of the shooter. In this case, the video image is recorded in the optical or infrared or other range.

Synchronous recording of audio signals with at least 3 sensitive elements and video images of the probable location of the sound source using one or more video recorders installed with the ability to change the shooting direction and position in space, allows you to accurately determine the location of the shooter on the ground.

Preliminary fixed fixing of the sensitive elements relative to the optical axis of the video recorder makes it easier to display the location of the shooter on the ground.

Signal processing, in which the moment of arrival of the muzzle wave and the frame closest in time to this moment from the recorded video, which marks the location of the shooter, is combined in time, which contributes to the high accuracy of determining both the location of the shooter on the ground and the distance to it.

Video recording, carried out in the optical, or infrared, or other range, allows you to determine the location of the sound source on the ground without prior topographic reference.

When implementing this method, you can not only determine the direction of the enemy, the range to him, but also “see” the sound sources directly on the battlefield, including “see” a single sound source, for example, a vehicle moving in the forest, by the sound of its engine .

In addition, an additional advantage of the proposed method is the ability to find directions only to one, the loudest sound source. With this formulation of the problem, the need to separate two incoherent sound sources in space disappears, since these sources are separated in time.

Additionally, if the image is recorded both in the optical and in the infrared range, and the video data is written in a circular video buffer (for at least 2 seconds), it becomes possible to see an infrared flash of powder gases on a section of the barrel. To do this, pull out the frame corresponding to the moment of the shot from the video buffer (t _shot in figure 2). To calculate the _shot t, recorded acoustic signals from microphones are used after the shock wave is detected. Next, the infrared flash is superimposed from the infrared video buffer onto the corresponding video buffer frame of the usual optical range.

Brief Description of the Drawings

In figures 1-6 shows the implementation of the proposed method for determining the location of the shooter on the ground.

The figure 1 presents a General diagram of the device, where 1 is the sensitive elements (microphones), 2 is the video recorder (video camera) connected to the monitor 3 and through an analog-to-digital converter 4 with the processor 5:

The figure 2 shows a signal processing diagram, where 6 is a shock wave - a sign of the beginning of sound recording, 7 - a muzzle wave, 8 - an arrow mark of the position.

The figure 3 shows a view of the correlation peak, which is the surface of the two-dimensional correlation function between the microphone channels when firing from the SVD rifle (Dragunov sniper rifle) from a distance of 330 meters.

The figure 4 shows the location of the same shot (SVD rifle from a distance of 330 meters) in the form of a colored spot with a brightness that varies depending on the magnitude of the amplitude.

The figure 5 shows the appearance of the experimental device, where 1 is a microphone, 2 is a video camera or digital camera, 9 is a sound-absorbing screen.

The figure 6 illustrates the calculated firing positions of the shooters superimposed on the video image.

The implementation of the invention

The method of determining the location of the shooter on the ground is as follows. Sensitive elements are pre-fixed motionless relative to the optical axis of each video recorder. Then, upon detection of shock waves from a passing supersonic bullet and a muzzle wave from expanding gases from the edge of the barrel, sound signals are recorded by at least 3 sensing elements and synchronously record video images of the area of the probable location of the sound source using one or more video recorders installed with the possibility of changes in shooting direction and position in space. In the subsequent signal processing, the moment of arrival of the muzzle wave and the frame closest in time to this moment from the recorded video sequence are combined in time, on which the arrow is marked. Moreover, the video image is recorded in the optical, or infrared, or other range.

The inventive method is implemented on the device shown in Fig. 1 and made in the form of 4 sensitive elements (microphones) 1, fixedly mounted relative to the optical axis of each video recording device 2, placed with the possibility of changing the shooting direction and position in space and connected to the monitor 3 and through analog-to-digital Converter 4 with a processor 5.

The inventive method of determining the location of the shooter on the ground is as follows. Sensitive elements 1 are pre-fixed motionless relative to the optical axis of the video recorder 2, each of which is installed with the possibility of changing the shooting direction and position in space. When a shock wave 6 is detected, simultaneously with the recording of sound signals using an amplitude-to-digital converter 4 and a processor 5, which register shock waves from a passing supersonic bullet and a muzzle wave 7 from expanding gases from a section of the barrel by at least 3 sensitive elements 1, they record video images of the probable location of the sound source by the video recorder 2. During subsequent signal processing, the moment of arrival of the muzzle wave and the closest frame from the recorded footage, on which they mark the location of arrow 8.

A possible embodiment of the experimental device shown in FIG. 5 was manufactured at the enterprise. Assuming that the speed of sound is also known from the point of view of increasing accuracy, it is more efficient to arrange all the sensitive elements (microphones) 1 in one plane perpendicular to the optical axis of the video recorder (video camera or digital camera) 2. In order to reduce the effect of reflected waves on the microphones side and rear, they are proposed to be placed in front of a sound-absorbing screen (for example, glass wool, foam rubber or other absorbent material) 3. When the microphones 1 are flat, the best Higher direction finding accuracy. The approximate size of the microphone antenna is approximately 20-30 cm. With such dimensions, a change in direction to the sound source by 1 degree corresponds to a change in the arrival of the wave front by 0.6 cm, which is in good agreement with the sampling frequency. At a sampling frequency of 41 KHz per channel, the wave manages to travel 0.7 cm between the clocks. Thus, it can be assumed that the device will be able to ensure the detection of a sound source with an accuracy of about 1 degree. In this regard, it is advisable to cover the video image with a grid in increments of 1 degree.

At the moment of detection of a muzzle wave, a video image is captured and a target mark indicating the range is imposed on this still image. Therefore, in the system, both a digital video camera and an infrared night-vision video camera can be used. In addition, in order to consider the position of the arrow indicated by the device with high magnification, a second long-focus video camera can be introduced into the device. In this case, you can provide a program that responds to movement.

In order to find out the practical feasibility of the proposed method, the following experiment was conducted at the test site. Eight microphones were located on a flat stand with a diameter of 35 cm in the same way as shown in Fig.5. To simulate a video camera, a digital camera was used, the optical axis of which coincided with the perpendicular to the plane of the microphones.

Figure 3 shows the surface of the two-dimensional correlation function between the channels of the microphones 1 when firing from an SVD rifle from a distance of 330 meters. The direction of arrival of sound waves is calculated by determining the maximum sum of inter-channel correlations for 4-16 channels.

In Fig. 4, the same shot is depicted as a colored spot with brightness varying depending on the magnitude of the amplitude. The brightness of the "superimposed sound image" depends on the magnitude of the correlations (energy flow in this direction). The color at a given point depends on the frequency of the sound.

The accuracy of determining the location of the shooter on the ground was determined on the device (figure 5) using a series of the same type of shots. The scatter of the calculated point of position of the shooter from shot to shot corresponds to a possible error. As can be seen from Fig.6, the scatter for 14 shots from two different firing positions was not more than 0.5 degrees both vertically and horizontally. This result demonstrated the potentially high accuracy of locating a shooter.

Based on the foregoing, we can say that the industrial applicability of the method of determining the location of the shooter on the ground is not in doubt. It can be used to search for snipers, to solve security tasks in law enforcement agencies, in the army, etc. When implementing the method, you can see the location of various sound sources on the battlefield. You can use infrared equipment or a night vision device as a video recording device, in addition to a video camera. A device for implementing the method can be quite compact. It does not require prior attachment on the ground, so it can be brought into operation in a short time. In principle, a system can be created without a monitor in the form of binoculars (in one of the focal planes a liquid crystal lattice can be located).

Literature

1. US No. 6178141, MKI: G 01 S 5/80, publ. 01/23/2001

2. www.metravib.fr.

Claims (2)

1. A method for determining the location of a shooter on the ground, including recording sound signals when sensing shock waves from a passing supersonic bullet and a muzzle wave from expanding gases from a barrel cut by sensitive elements, processing these signals using a processor, based on which the location of the sound source is different the fact that the sensitive elements are pre-fixed motionless relative to the optical axis of one or more video recording devices, when registering shock waves about tons of a flying supersonic bullet and a muzzle wave from expanding gases from a barrel cut synchronously with the recording of sound signals, at least 3 sensitive elements record a video image of the probable location of the sound source using one or more video recorders installed with the ability to change the shooting direction and position in space , during subsequent processing of the signals, the moment of arrival of the muzzle wave and the frame closest in time to this moment from the recorded form are combined in time oryada to which the mark is applied for and the location of the shooter. 2. The method for determining the location of the shooter on the ground according to claim 1, characterized in that the video image is recorded in the optical or infrared range.

Images