Drone Detection Technology - Radio Detection

Radio detection is to detect drone targets by detecting the measurement and control and image

transmission signals of drones.Radio detection equipment not only has the function of target detection and discovery,

but also has certain target recognition capabilities. 

The received signal can be identified by analyzing the signal characteristics to determine whether it is a drone measurement

and control or image transmission signal. At the same time, a database of target signal characteristics of common drone models

can be established. After the signal is detected, it can be compared and analyzed with the characteristic signals in the database

to identify the specific type and model of the target drone.

At present, most common consumer drones on the market use 2.4GHz and 5.8GHz frequency bands.

The "Use of Frequency of Drone Systems" issued by the Ministry of Industry and Information Technology of my country

stipulates that the 840.5MHz~845MHz, 1430MHz~1444MHz and 2408MHz~2440MHz frequency bands are used for

drone pilot aircraft systems.

The 840.5MHz~845MHz frequency band can be used for the uplink remote control link of the drone system, among which

841MHz~845MHz can also be used in time division for the uplink remote control and downlink telemetry information transmission

link of the drone system.

The 1430MHz~1446MHz frequency band can be used for the downlink telemetry and information transmission link of the UAV system.

The 1430MHz~1434MHz frequency band should be used for police UAV and helicopter video transmission first. If necessary,

the 1434MHz~1442MHz can also be used for police helicopter video transmission. When UAVs are deployed in urban areas, the frequency

band below 1442MHz should be used.

The 2408MHz~2440MHz frequency band can be used for the downlink of the UAV system. When the radio station is working,

it shall not affect other legal radio services, nor seek radio interference protection.

At the same time, most civilian consumer-grade UAVs use the free ISM frequency band as the communication frequency.
The ISM frequency band is defined by the International Telecommunication Union and is mainly open to industrial,

scientific and medical institutions for free use. It does not require the approval of the radio management agency.

The ISM frequency band suitable for drone communication is mainly in the microwave band, including: 433.05~434.79MHz,

902~928MHz, 2.400~2.4835GHz, 5.725~5.875GHz.
Some enthusiasts personally assemble drones and cross-country drones, which use the amateur radio frequency bands

specified by the national radio management department as the frequency of drone flight control and image transmission

communication, mainly concentrated in the two frequency bands of: 430MHz~440MHz and 1260MHz~1300MHz.

In summary, the common working frequency bands that drone detection equipment needs to meet include:

430MHz~440MHz, 840.5MHz~845MHz, 902MHz~928MHz, 1260MHz~1300MHz, 1430MHz~1444MHz,

2.400GHz~2.4835GHz, 5.725GHz~5.875GHz

A single radio detection device usually only has a measurement function. Multiple radio detection devices can be used

 in coordination to locate the target through cross-positioning or using the TDOA technology system.

Radio detection is a passive detection device that does not radiate electromagnetic signals outward and does not

interfere with the surrounding electromagnetic environment.

The disadvantage is that it is greatly affected by the surrounding electromagnetic environment and the 

detection accuracy is not high.

Protocol cracking

After collecting the radio signal, the drone signal is accurately demodulated and cracked through the algorithm, including frequency,

down-conversion, analog-to-digital conversion, filtering, despreading, demodulation and decoding, and then the protocol is cracked,

including link layer, network layer and application layer, decompression and decryption, etc.;

It is transmitted to the back-end processing platform server through the network, and the terminal processing platform server identifies

the received drone signal, analyzes the characteristics of the suspected drone radio signal, and analyzes and matches it with the

characteristics in the cracking protocol database for accurate identification. If the signal belongs to the whitelist, no warning and defense

will be performed. If the signal is not in the whitelist, the system will automatically warn.

Message parsing

Message parsing refers to parsing the message sent by the received drone to extract useful information from it.

Drone messages generally include relevant information such as the drone's location, speed, attitude, battery power, etc.

Parsing drone messages can help users understand the status of the drone and make corresponding control and decisions.

Strength: Long detection distance, good concealment, can identify target aircraft and locate its operator, strong all-weather working ability

Weakness: It is difficult to detect drones in radio silence, the direction finding and positioning accuracy is low, and they are easily

affected by the physical and electromagnetic environment.

 

Drone Detection Technology - Sound Detection

 

Sound detection detects drone targets by detecting the sound of the propellers rotating when the drone is flying. Its core technology

is sound recognition, and the main detection frequency is 0.3kHz~20kHz. It matches with the existing drone audio database and

extracts the soundprint features of the drone propeller rotation sound to identify the target.

This technology is suitable for close-range detection in a quiet environment, and the detection distance accuracy will decrease

 in the noisy background environment of the city. The microphone array mainly comes in the form of linear four-array and spherical

array. The main positioning algorithms include cross-power spectrum method, TDOA method, etc. At present, the best combination is

spherical array and TDOA method.At present, sound detection is mainly used as an auxiliary means of photoelectric detection, and its

performance as a single detection source is poor.

Strength: Low cost, high safety, easy to use, good concealment, low power consumption of detection means, and can realize

all-weather early warning detection

Weakness: Unable to identify drones unknown to the database, and the detection distance is seriously affected by environmental noise

 

Drone Jamming Technology-Link Jamming

 

Anti Drone can be generally divided into two categories: "soft kill" and "hard damage".

Soft kill refers to the use of electronic interference, navigation deception and other means to make drones unable

to work normally, thereby reducing the threat of drones. "Hard damage" refers to the use of physical damage to disable and

 fall drones, thereby eliminating the threat of drones.

The drone loses control information and location information by interfering with the drone's measurement and control link

and navigation link. Most drones have designed their own safety protection mechanisms. When the control information

and navigation information are lost, the drone will interrupt the mission being performed and hover, circle or return.

At present, radio interference mainly adopts high-power broadband blocking interference, and the interference frequency

covers the 300MHz~6GHz frequency band, covering the common drone measurement and control and navigation frequency

bands. Radio interference equipment can be fixed equipment or handheld portable equipment.

At present, portable radio interference equipment is the most widely used equipment in daily anti-drone protection.

In recent years, portable

 interference equipment has also been continuously developed. On the basis of a single interference function, a detection

and alarm function has also been added, which can enable auxiliary operators to detect drone targets.

 

 

Drone Jamming Technology - Acoustic Jamming

 

Acoustic interference technology is to emit sound waves with the same frequency as the drone's gyroscope, causing the gyroscope

to resonate and output error information, thereby interfering with the stable flight of the target drone, and ultimately causing it to fail

to fly normally and crash.

Acoustic interference technology can cause the target drone to hover or hover in the air, land, or return. For the first two response

modes, safety issues must be given top priority. If in a densely populated area or urban environment, it is necessary to evacuate the

ground crowd and clean up the ground facilities as soon as possible. For drones hovering in the air, they can be captured using lift

equipment or netting technology.

At present, the technology is still in the theoretical research and development stage, and the attenuation problem that occurs during

the propagation of sound waves will be a technical problem that needs to be solved in the future.

Strength: Safe, controllable, easy to operate

Weakness: Difficult, costly, still in the theoretical research and development stage, possible collateral damage, attenuation

during sound wave propagation

 

Drone Jamming Technology - Deception Control

 

Radio signal hijacking

Radio signal hijacking technology is to analyze the link signal and communication protocol of the drone, and use the analysis

results to autonomously generate deception signals and inject them into the link terminal to achieve control over the

target drone.Radio signal hijacking is a relatively advanced technology in the field of domestic Anti drone . Its advancement is

more reflected in its high technical difficulty and poor universality. With the continuous development of science and technology,

drone communication protocols and encryption algorithms are also constantly upgrading and improving, and the difficulty of

cracking drone communication protocols is gradually increasing.

The current limitations are mainly due to the difficulty of technical construction and implementation, and it is difficult to promote

 and use on a large scale. Different drones need different cracking methods. If their communication links are protected in professional

technology, they may be able to resist this deception control technology to the maximum extent.

Strength: Can work independently and capture drones without damage
Weakness: The target has poor universality, high technical difficulty, high difficulty in signal cracking, and is difficult to promote and

use on a large scale

 

Navigation deception

Compared with high-power suppression of radio interference, navigation deception is a smart way of disposal.
Navigation spoofing technology is to perform time and Doppler modulation on the received UAV navigation signal to give false

navigation information, so that the navigation terminal is located at the wrong position set by the spoof signal, thereby deceiving

the return point and trajectory of the target UAV.

Strength: It works better for drones that rely on high satellite navigation signals.

Weakness: The technology is difficult and has poor effect on drones with high automation and intelligence levels.

 

 

Drone Jamming Technology - Hard Kill

 

Artillery and anti-aircraft missile technology belong to the traditional air defense mode and are commonly used to attack drones.

This technical means can be used to destroy drones with heavy flight weight and high flight altitude.

With the continuous development and upgrading of drone technology, modern air defense systems have also expanded precision

guidance, electronic interference and other technologies on the basis of past air defense systems, and have the ability to detect targets

and track guidance.The existing air defense weapon system can fight against drones to a certain extent, but there are also limitations,

mainly reflected in the difficulty of multi-target combat, which is difficult to meet the combat needs of drone clusters, and with the

widespread use of "low, slow and small" drones, the high cost of artillery and anti-aircraft missiles is destined to be difficult to become

the main countermeasure.High-energy laser weapons are a new concept weapon and a type of directed energy weapon. Its working

principle is to use high-energy lasers to burn drones. This method is mainly used in combat scenarios to deal with drones with greater

threats such as carrying weapons and dangerous goods, or drones that cannot be handled by electronic interference and navigation

deception, to ensure that drones do not enter the protection area and cannot pose a threat. Traditional firepower strike weapons have

the problems of low efficiency and high cost when attacking drones. 

Compared with traditional firepower strike weapons, laser weapons have the characteristics of fast firing speed, low interception

cost and high strike accuracy. They are a cost-effective means of attacking and destroying drones. However, laser weapons are greatly

affected by the weather environment, and the overall cost is relatively high compared to electronic jamming equipment.

Microwave weapon technology is to form a highly concentrated, high-power and directional microwave beam in a short time through

directional radiation of electromagnetic waves, which enters the interior of drone airborne equipment to physically destroy electronic

components, making them ineffective or disabled, thereby damaging the target drone.

Microwave weapons are one of the key areas of military research in various countries around the world. They are usually used to interfere

with the optoelectronic equipment of military targets and weapons at a long distance, and to kill living targets at close range. Among them,

high-power microwave weapons integrate soft and hard killing functions, which can be used for strategic defense or tactical interception.

They can produce different effects at different power densities, and realize the drone counter-measure capabilities of detection, tracking and

destruction in the same system, with outstanding military prospects and combat advantages.

Strength: High lethality, good damage effect, high combat cost-effectiveness, fast response speed, high hit accuracy, strong anti-interference

ability, and can deal with multiple targets in a short time

Weakness: High cost, high aiming requirements, limited range, difficult to destroy armored and rotating targets, causes permanent damage

to targets, and difficult to obtain intelligence data

 

Drone Jamming Technology - Net Capture

 

Netting technology is to capture drones by wrapping around their rotors and take them away from the mission area. For drones that

may carry dangerous items, they are taken to a safe location for safe disposal without collateral damage.

Since the cost of "low, slow and small" drones is relatively low, if the opponent adopts a multi-batch, decentralized approach, it will

increase the defense pressure on the defender, resulting in an increase in combat costs and a highly saturated air defense channel.

Therefore, in addition to conventional firepower damage technology, the damage and capture technology for drones also includes

laser weapon technology, microwave weapon technology, and netting technology. By using this type of technology, Anti drone

equipment can efficiently form a ground-to-air strike network, and carry out firepower destruction and capture of target drones

based on the intelligence information provided by the reconnaissance intelligence system.

Strength: Low cost and little target damage

Weakness: Low hit rate, difficult to fight against drone clusters, high requirements and difficulty for team countermeasures, poor

effect on fixed-wing drones

 

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