1. Suppressed radio interference
Suppressive radio jamming is perhaps the most direct, effective and least expensive countermeasure. Suppressive countermeasures are actually radio suppression and interference to the remote control links, information transmission links and GPS navigation signals of illegal drones, making illegal drones blind, deaf and dumb in a certain area. Even with the role of UAV inertial navigation, it can only maintain the original attitude for a short time and cannot continue to move according to the wishes of the operator.
There are two types, one is a drone jammer system and the other is a portable drone gun jammer.
Generally speaking, the wireless data link of consumer low-slow and small drones has about 2-3 commonly used frequency bands, namely 2.4GHZ, 5.8GHz and 915MHZ. These three frequency bands are often the main sources of illegal consumer drones. frequency band. For professional UAVs, the professional frequency bands for UAV data links stipulated by the Ministry of Industry and Information Technology of my country are 845MHZ and 1.4GHZ. Generally speaking, because professional drones in my country are often used by government departments or even law enforcement departments, they are in a strictly controlled state, and the probability of illegal use is very low. In addition, the production of wireless data link products in these two dedicated frequency bands is low and The price is high, and these two frequency bands are rarely used in general consumer drones. Therefore, general anti-jammers are mainly concentrated in the three frequency bands of 2.4GHZ, 5.8GHz and 915MHZ.
In principle, as long as the amplitude of the radio suppression signal is strong enough and the frequency can cover the above satellite navigation frequency points, then the drone will lose the ability to automatically navigate.
It can be seen from the above analysis that there is no technical difficulty in suppressing the UAV countermeasures, because the frequency points of the communication data link and the navigation signal are public, as long as a noise signal with the same frequency point and a strong enough amplitude is created , can play a suppressing effect. Simply put, this countermeasure is the simplest, cruder and less technical solution! But this solution is simple but effective.
Of course, in addition to consumer low-slow and small systems, for some professional UAVs, even military UAVs, this simple suppression method is also effective, but the requirements for transmit power are even higher. No discussion here for now.
2. Deceptive drone jamming systems
Compared with the simple repressive interference countermeasure system, the deceptive or induced countermeasure system has higher technical content. Deceptive countermeasures are composed of two major parts: data link deception and navigation signal deception.
The difficulty of data link spoofing is relatively high. First of all, we must detect and analyze the data link of the target UAV. If we can crack all parameters such as frequency, bandwidth, modulation method and communication protocol of the entire data link, this It means that we can completely take over the illegally invaded drones! This work is relatively difficult, and it is quite difficult for frequency hopping communication and data links using different encryption and decryption technologies! If it is known in the market All kinds of unmanned aerial vehicles in China have achieved countermeasures based on data link cracking technology, and the workload and difficulty are almost impossible. Even if a certain drone is successfully cracked, if the manufacturer adjusts the technical system and encryption method of the data link, all the work has to be done all over again! The countermeasure system based on the data link cracking technology is often adopted by the military, That is to conduct research and crack on a specific type of military UAV in the place, and take over the capture. Iran has captured the U.S. military's RQ47 UAV many times, using this technical route.
The deception of satellite navigation signals is interference, mainly for GPS/GLONASS/BD navigation systems, which transmit false satellite navigation signals. If the power of the fake satellite navigation signal is much higher than the real GPS navigation signal, then the drone will fly according to the fake navigation signal until it flies out of the protected area, and land or crash by itself, realizing the critical area. the purpose of protection. The frequency and format of the navigation signal are relatively fixed and even transparent. Therefore, the countermeasures implemented by launching false satellite navigation signals are simpler than the technology of data link tubes. If the use of false navigation signals can induce the landing of illegal drones and capture them perfectly, it will be more effective for future case-solving and evidence collection. This technical system is more technical than rudely jamming the drone and making it land and crash.
Of course, the best technical solution is to take over the data link and release false navigation signals. The perfect capture of drones does not provide evidence for solving the case! However, in the civilian field, the economic benefits of various countermeasures Sex is also very important. If it takes a lot of manpower and material resources, it seems that it is not worth it just for a "low, slow and small" of several thousand yuan or tens of thousands of yuan; and if it is a perfect capture of an American RQ47 (to the Iran), or Israel's Heron series, the significance is very significant.