Method for detecting an unmanned aerial vehicle in flight

Abstract

FIELD: aviation.SUBSTANCE: invention relates to the field of object detection in airspace, and more specifically to methods for determining the in-flight status of unmanned aerial vehicles (UAVs) by measuring the frequency of electromagnetic waves. In the claimed method, electromagnetic waves from a radiation source are used to probe a controlled unmanned aerial vehicle, and the electromagnetic waves reflected from it are received by a radiation detector. When the UAV is stationary, the reflected wave front is calculated at a distance N⋅λ, where N is the number of oscillations per time τ, λ is the length of the emitted wave, the distance is estimated as c⋅ τ, where c is the speed of wave propagation in free space, the obtained distances are equated. When the detected UAV moves in the direction of the detector, the front of the reflected waves is determined at a distance (c–vs) τ, where vs is the speed of the source, the equality (c–vs)τ =N⋅λ1 is formed, where λ1 is the wavelength emitted by a moving source. The wavelength emitted by a moving source is calculated and, taking into account the wave frequencies emitted by a stationary and moving source, a decision is made on the detection of the UAV moving towards the detector in flight.EFFECT: simplifying the process of detecting an unmanned aerial vehicle in flight.3 cl, 1 dwg

Description

[0001] The invention relates to the field of detecting objects in airspace, and more specifically to methods for determining the flight status of unmanned aerial vehicles (UAVs) by measuring the frequency of electromagnetic waves.

[0002] A system and method for detecting and countering unmanned aerial vehicles are known (see RU 2755603 C2, 17.09.2021), according to which the method includes the stages of: a) detecting an unknown flying object in a controlled airspace zone using a primary detection means including a lidar; b) determining, using a primary detection means including a lidar, the spatial coordinates of the detected unknown flying object, which are sent to a control and classification means; c) capturing the detected unknown flying object using a recognition means containing at least one video camera; d) classifying, using a control and classification means, the detected unknown flying object based on the analysis of at least one image received from the recognition means, wherein the said analysis is performed using neural networks;d) when an unknown aircraft is identified as a UAV using a control and classification device, the UAV is identified; e) when a UAV is identified as an unknown UAV, targeted radio suppression of the UAV control signal is carried out using a neutralization device until the UAV leaves the controlled airspace.

[0003] The disadvantages of this well-known technical solution include the short range of lidars and their low accuracy in detecting flying objects due to heavy precipitation in the form of rain, snow, hail, as well as the influence of fog and dust.

[0004] The closest technical solution to the proposed one is the method for detecting small unmanned aerial vehicles (see RU 2735070 C1, 10 / 27 / 2020), adopted by the author as a prototype, the operating principle of which consists in the simultaneous radar measurement of the Doppler and micro-Doppler effects caused by the flight of UAVs with rotating propellers and the flight of birds with flapping wings, and the measurement of the acoustic velocity of particles of acoustic waves emitted by the rotating propellers of UAVs, which makes it possible to identify the radar and acoustic signatures of UAVs and birds by comparing them with known signatures of UAVs and birds from a constantly updated library of known signatures.A method for detecting small UAVs is proposed in which radar signatures and acoustic signatures of objects in the airspace of observation are received simultaneously, and then the received signatures of these objects are compared with known signatures of unmanned aerial vehicles and with known signatures of birds.

[0005] One of the disadvantages of this method of detecting small unmanned aerial vehicles (UAVs) in terms of acoustic signature is the influence of background noise, the limited detection range, and the effects of wind and precipitation. A common drawback of using both radar and acoustic signatures is the difficulty in creating standard signatures due to the varying signatures of different bird species and the dimensions of the aircraft being detected.

[0006] The technical result of the proposed method is to simplify the process of detecting an unmanned aerial vehicle in flight.

[0007] The technical result is achieved in that in the method for detecting an unmanned aerial vehicle in flight, the controlled unmanned aerial vehicle is probed with electromagnetic waves from a radiation source, the electromagnetic waves reflected from it are received by a radiation receiver, when the unmanned aerial vehicle is stationary, the front of the reflected waves is calculated at a distance of N⋅λ, where N is the number of oscillations during time τ, λ is the length of the emitted wave, the distance is estimated in the form of c⋅τ, where c is the speed of propagation of waves in free space, the obtained distances are equated c⋅τ = N⋅λ, when the detected aircraft is moving in the direction of the receiver, the front of the reflected waves is determined at a distance of (c-v и )τ, where v и - the speed of movement of the source, form the equality (c-v и )τ=Nλ1, where λ1 is the wavelength emitted by a moving source, and produces a division of the equality (c-v и)τ=Nλ1by the equality c⋅τ=N⋅λ, the wavelength emitted by a moving source is calculated using the formula λ1=λ(c-v и )c, and by frequency, calculated by the formula f1=f(c / c-v и ), taking into account λ=c / f, λ1=c / f1, where f is the frequency of the wave emitted by a stationary source, f1 is the frequency of the wave emitted by a moving source, we judge the detection of an unmanned aerial vehicle moving towards the receiver in flight, while when the controlled aircraft moves in the opposite direction from the receiver, the frequency is calculated using the formula f1=f⋅c / (c+v и ), they judge the detection of an unmanned aerial vehicle (UAV) moving in the opposite direction from the receiver during flight. Furthermore, the radiation source and receiver are mounted on the frame of a stationary UAV used to detect the target UAV in flight.

[0008] The essence of the claimed invention, characterized by the combination of the above-mentioned features, is that by measuring the frequency of the received reflected electromagnetic oscillations from the sought unmanned aerial vehicle during its movement in two opposite directions, it is possible to detect the sought aircraft in flight.

[0009] The presence of the set of listed existing features in the claimed method makes it possible to solve the problem of detecting an unmanned aerial vehicle in airspace by measuring the frequency of received reflected electromagnetic oscillations from the detected object as it moves in two opposite directions with the desired technical result, i.e., simplifying the process of detecting an unmanned aerial vehicle in flight.

[0010] The drawing shows a functional diagram of a device that implements this method.

[0011] The method operates as follows. A stationary unmanned aerial vehicle (UAV) is launched into a controlled airspace and hovers at a predetermined altitude. According to the operating principle of this UAV, in addition to the devices and units necessary for performing various maneuvers, its frame also contains a source and receiver of ultra-high-frequency electromagnetic radiation, along with associated secondary equipment for converting and displaying information and other signals. The primary purpose of this UAV is to detect the presence of unauthorized UAVs in the controlled airspace.

[0012] Let a detected aircraft appear in the airspace of a stationary aircraft and be located at some distance from the stationary aircraft in a suspended, motionless state. The target stationary aircraft is probed by oscillations emitted by a radiation source, and the radiation receiver receives the oscillations reflected from the probed aircraft. In this case, based on its reflective properties, the target aircraft can be considered a second source of electromagnetic oscillations received by a radiation receiver located on the frame of the stationary aircraft. Let us assume that the second source completes N complete oscillations over a time τ. During this time, the front of this wave will be at a distance N⋅λ from the second source, where λ is the wavelength of the wave emitted by the second source. If the velocity of wave propagation in air is c, then the following equality is valid: c⋅τ=N⋅λ (1).

[0013] Now let the desired aircraft with the second source (conditional) move towards the radiation receiver (the receiver is located on the frame of the stationary aircraft) at a speed v и In time τ it will travel a distance v и ⋅τ. The wave front moves in the air at a speed of c and by the time τ the front will be at a distance of (c-v и )τ from the second source. Since during this time the source will complete N oscillations and emit N wavelengths, the equality (c-v) holds. и )τ=N⋅λ1(2), where λ1 is the wavelength emitted by the second moving source of the desired apparatus. We divide equality (2) by equality (1) and from the resulting relation we calculate λ1 as λ1=λ-(c-v и) / с (3). From expression (3) it is evident that as the second source moves (approaches) towards the receiver, the wavelength of the electromagnetic wave emitted by this source decreases. Taking into account the relationship between wavelength and frequency (λ=c / f, λ1=c / f1, where f is the frequency of the wave emitted by a stationary source, f1 is the frequency of the wave emitted by a moving source), from (3) we obtain the formula for frequencies f1=f⋅c / (с-v и ) (4). From (4) it is evident that as the second source moves toward the receiver, the frequency of the wave received by the receiver increases. Consequently, by measuring the frequency from formula (4), it is possible to detect the target aircraft approaching the stationary aircraft within the range of the stationary aircraft.

[0014] In the case of movement of the sought-after aircraft in the opposite direction from the stationary aircraft at a speed of v иsimilar reasoning to the previous ones leads to the conclusion that the wavelength emitted by the second source increases: λ1=λ(c+v и ) / c (5). It follows that the frequency of oscillations received by the receiver decreases as the source moves away from the receiver: f1=f⋅c / (c+v и ) (6). Therefore, by measuring the frequency from formula (6), it is possible to detect the desired aircraft moving away from the stationary apparatus in the zone of action of the stationary aircraft.

[0015] The proposed method can also be used to detect a target unmanned aerial vehicle when a stationary aircraft is moving relative to the target, as well as when both aircraft are moving simultaneously. This will be discussed below.

[0016] Now let a stationary aircraft with a radiation source and receiver move with a speed v пin the direction of the second source of the sought-after aircraft when it is stationary. In this case, taking into account the above reasoning, for the frequency of oscillations received by the receiver of a stationary aircraft, we can write f1 = f(c + v п ) / c (7). From the resulting formula it is clear that the frequency increases.

[0017] If the receiver moves from the second source with a speed v п , the speed of the wave relative to the receiver will be equal to c - v п . Repeating the previous reasoning, for the frequency received by the receiver, we obtain the formula f1=f(cv п ) / c (8). Here the frequency decreases.

[0018] If both the source and receiver move simultaneously, then both effects occur: the wavelength of the source's emitted wavelength in the air changes, and the wave's velocity relative to the receiver changes. In this case, formulas (4), (6), (7), and (8) can be generalized as follows:

[0019] In (9), the upper sign is taken in the numerator (denominator) if the velocity of the receiver (source) or wave is directed toward the source (receiver). Otherwise, the lower sign is taken. From (9), it follows that as the source and receiver approach each other, the received frequency increases, and as they move further apart, it decreases. If the source and receiver move so that the distance between them remains constant, no change in frequency is observed.

[0020] The functional diagram of the device implementing this method in terms of probing the detected unmanned aerial vehicle and receiving the reflected signal from it (the case of the sought device approaching and moving away from the stationary device) is shown in the drawing.

[0021] The device comprises a microwave generator 1, a circulator 2, a transmitting and receiving horn antenna 3, and a frequency meter 4. The detected unmanned aerial vehicle is indicated by the number 5 in the figure. All microwave circuit units of this device are located on the frame of the stationary unmanned aerial vehicle.

[0022] The device operates as follows. The device operates as follows. Electromagnetic oscillations of a fixed frequency, for example, 10 GHz, are directed from the output of microwave generator 1 to the first arm of circulator 2. The signal, picked up from the second arm of this microwave unit, is then fed to the transmitting and receiving horn antenna 3. The horn antenna's emitted signal irradiates the target aircraft 5. The same antenna then receives the microwave signal reflected from the target aircraft. The signal captured by the antenna, in accordance with the operating principle of the circulator, is picked up from its third arm and then sent to the input of frequency meter 4. This meter measures the frequency f1, which is characterized by the detection of the target aircraft approaching or moving away from the receiver.

[0023] In the text of the description of the proposed method, the blocks and devices that carry out the launch, descent of a stationary unmanned aerial vehicle and other maneuvers during its flight are not carried out.

[0024] Thus, in the proposed technical solution, by measuring the frequency of the received reflected electromagnetic oscillations from the desired unmanned aerial vehicle as it moves in two opposite directions relative to the receiver, it is possible to simplify the process of detecting the unmanned aerial vehicle in flight.

Claims

1. A method for detecting an unmanned aerial vehicle in flight, characterized by the fact that the controlled unmanned aerial vehicle is probed by electromagnetic waves from a radiation source, the radiation receiver receives the electromagnetic waves reflected from it, when the unmanned aerial vehicle is stationary, the front of the reflected waves is calculated at a distance of N⋅λ, where N is the number of oscillations in time τ, λ is the length of the emitted wave, the distance is estimated in the form of c⋅τ, where c is the speed of propagation of waves in free space, the obtained distances are equated c⋅τ = N⋅λ, when the detected aircraft moves in the direction of the receiver, the front of the reflected waves is determined at a distance of (c-v и )τ, where v и - the speed of movement of the source, form the equality (c-v и )τ=N⋅λ1, where λ1 is the wavelength emitted by a moving source, and the equality (c-v) is divided и)τ=N⋅λ1by the equality c⋅τ=N⋅λ, the wavelength emitted by a moving source is calculated using the formula λ1=λ(c-v и ) s, and by frequency, calculated by the formula f1=f(c / c-v и ), taking into account λ=c / f, λ1=c / f1, where f is the frequency of the wave emitted by a stationary source, f1 is the frequency of the wave emitted by a moving source, we judge the detection of an unmanned aerial vehicle moving towards the receiver in flight.

2. The method according to paragraph 1, characterized in that when the controlled aircraft moves in the opposite direction from the receiver, the frequency is calculated using the formula f1=f⋅c / (c+v и ), judge the detection of an unmanned aerial vehicle in flight moving in the opposite direction from the receiver.

3. The method according to paragraph 1, characterized in that the radiation source and receiver are installed on the frame of a stationary unmanned aerial vehicle used to detect the desired unmanned aerial vehicle in flight.

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