Once again about the prospects for the development of radio-controlled explosive devices and methods of combating them. The article was updated in 2023.

Radio-controlled explosive devices (RCED) are increasingly used in terrorist attacks. There are many reasons for this phenomenon. The main ones are:

• the possibility of early and, therefore, relatively safe mining of the place where a terrorist act is committed;
• wide possibilities for covert observation of the target of the attack for a long time and multi-variant remote detonation of the means of destruction;
• a large selection of ammunition used for detonation — from a gas cylinder to an artillery shell, their hidden placement on the surface of the earth, in the ground, in buildings, cars, elevators and in numerous other places;
• higher efficiency of this method compared to others in organizing terrorist acts against professionally protected VIPs: government officials, major businessmen, etc.;
• the possibility of hitting highly protected stationary and moving objects, including those moving at high speed;
• the absence of external signs of a terrorist act in the event of failure of the command-transmitting and (or) actuator device with the possibility of its subsequent repetition;
• comparative simplicity of organizing hidden waste after a terrorist act;
• availability of legal acquisition of radio components, radio transmitting and receiving devices necessary for the manufacture of radio detonators, low requirements for the qualifications of developers, ease of manufacture and comparatively low cost of radio detonators.

Numerous reports in the open press and on television confirm the widespread use of RUVs to commit terrorist acts. It is enough to recall the individual widely known facts of the death of the Italian judge Falcone, the failed assassination attempts on the President of the Republic of Georgia E. Shevardnadze and the Vice-Mayor of Moscow V. Shantsev. The author is not aware of a single case of detention of an operator who carries out a remote detonation of a RUV actuator.

In the historical period from 1929, when the first radio-controlled explosive device in the world appeared in service with the workers' and peasants' Red Army, and until 1991, the use of RCED for terrorist purposes was practically excluded. This is explained by the closed nature of developments in the field of this type of weapon, the lack of a wide range of necessary electronic components, as well as the high efficiency of special services in identifying and preventing the activities of persons engaged in the manufacture of RCED.

The situation changed dramatically for the worse after the collapse of the USSR and the outbreak of numerous armed conflicts in Russia and neighboring countries. Illegal armed groups, having a solid financial base, were able to attract unemployed specialists to manufacture RUV. During the military operations, techniques and methods for their use against federal forces, employees of other law enforcement agencies, and for the destruction of persons who collaborated with the federal government were practiced. Echoes of these events after the end of active military operations are observed at the present time. A clear confirmation of this is the discovery of radio-controlled explosive devices, according to media reports, from militants who took hostage the artists and spectators of the play «Nord-Ost». In fact, this means that it is becoming increasingly difficult to control the unauthorized use of RUV, and it is necessary to counter them not only by special services, but also by security services of private companies and security agencies.

Justification of a set of organizational and technical measures to combat radio-controlled explosive devices is a complex problem. It can be effective only if it is carried out continuously, actively, systematically, with forecasting and anticipation of the actions of the opposing side. Unfortunately, at least from media reports, there are no signs of organized counteraction to the use of RCEDs. Of course, this area of ​​activity is within the competence of the special services and is hidden from an outside observer. However, the high scientific and technical potential of commercial organizations engaged in the development of special equipment can make a significant contribution to solving this problem. A review of scientific and technical sources shows that at present, the most widespread are two methods of combating RCEDs: suppression of control signals using portable and automobile (transportable) broadband interference transmitters, as well as remote detection of installed executive devices of the radio line by non-linear radars with their subsequent removal (destruction). The author has not set and does not intend to set himself an ambitious task of expert evaluation of these means of combating radio-controlled explosive devices, especially since many developed models are comparable or even superior to the best foreign analogues in their technical, ergonomic, and operational characteristics at an acceptable cost and reliability. The goal is seen in something else, namely, to evaluate the state, immediate and subsequent prospects for improving radio-controlled explosive devices and to discuss a possible set of technical and organizational measures to combat them.

The most complete technical description of the operating principle, main technical characteristics of radio-controlled explosive devices, probable application options and methods of combating radio-controlled explosive devices are presented in [1]. The authors of the article provide convincing evidence in favor of the effectiveness of using mobile barrier jamming transmitters (MPP), portable and transportable. Without entering into a discussion, I would like to provide additional arguments, on the one hand confirming their correctness, and on the other requiring clarification of the composition and characteristics of radio countermeasure equipment for radio-controlled explosive devices.

Before discussing possible methods of combating radio-controlled explosive devices, let us evaluate their main technical characteristics and areas of use in more detail. Conventionally, all radio-controlled explosive devices can be divided into non-professional, semi-professional and professional.

Professional radio-controlled explosive devices are developed by specialized research and production institutions by orders of law enforcement agencies and, as a rule, have high technical characteristics, various body shapes, a lot of devices, and also wide functional capabilities. Since professional radio lines are subject to strict accounting in law enforcement agencies around the world, their acquisition and subsequent use for terrorist purposes is extremely difficult, one can even consider it impossible. At least, the author does not know of a single case of using such devices by terrorists.

The most frequently used terrorist devices are non-professionally and semi-professionally manufactured radio-controlled explosive devices. The paradox is that, unlike other types of weapons, terrorists are ready to use homemade radio lines to achieve their goals, even at the risk of being blown up by them during installation. There can be only one explanation for this: the effectiveness of remotely detonated explosive charges is so high that it justifies any losses. Considering that the vast majority of RCEDs are used against individuals protected by private organizations, comprehensive counteraction to them inevitably becomes one of the most important tasks of security services and security companies.

Assessing the prospects for the development of radio-controlled explosive devices, the following forecast can be made based on an analysis of the facts of their use according to open press materials.

In modern conditions, it is not difficult to find unemployed highly qualified specialists who can be involved in the development and production of modern RUVs for the purpose of their subsequent illegal or semi-legal sale. By investing relatively small financial resources using the developments of the military-industrial complex, modern radio links can be created in a short time, in terms of their characteristics and capabilities not inferior to the models in service with law enforcement agencies and surpassing them in miniaturization, minimal cost and modernization capabilities. Therefore, it should be expected that first of all, radio-controlled explosive devices of semi-professional manufacture will be developed, approaching professional means, and in some ways surpassing them in noise immunity, control range, safety and functional capabilities.

At the same time, it is also possible to use unprofessionally manufactured radio lines. Not all criminal structures have the ability to acquire modern and, therefore, more expensive means of remote detonation of explosive charges. It can be assumed that the technical characteristics of this type of radio lines will not undergo significant changes. They will continue to be manufactured by random people to solve immediate problems of a criminal and terrorist nature.

Finally, we should expect an improvement in the tactics of using radio lines, borrowed from militants of the North Caucasus and already introduced throughout Russia. These are repeated remotely controlled detonations of explosive charges, the use of standard and homemade fragmentation ammunition, numerous methods of disguising radioactive waste as seemingly safe household items, and many others.

Predicting the functional capabilities of radio links, it can be assumed that in the coming years the main method will remain the remote detonation of single explosive charges. It is possible to increase the scale of using standard and homemade fragmentation ammunition. The control range will remain the same, and in most cases will be several hundred meters. When using semi-professional radio links, one should expect the remote detonation of two or more explosive charges installed on a small area of ​​territory, including at different control frequencies. The transmission of control signals will still be carried out mainly in the ultra-short-wave range. The choice of the time of detonation of charges (and the errors associated with this control method) will mainly be assigned to the demolition operator.

In the future, we can expect the emergence of radio links operating in the 10-20 MHz radio wave ranges, as well as the use of new control methods consisting of transferring ammunition from a safe state to a combat state with subsequent explosion in automatic mode upon a signal from the target sensor. In this regard, it is possible to increase the number of cases of using radio links to destroy moving objects, including high-speed ones. It is expected that sensors will appear that detect powerful broadband interference. The control range may increase to 1-3 kilometers.

Comparing the technical and operational characteristics of unprofessionally and semi-professionally manufactured radio links, one can make the obvious conclusion at first glance that it is much more difficult to combat the latter than the former. However, this is not entirely true. The main danger of unprofessionally manufactured RC devices lies precisely in the unpredictability of their reaction to external influences. Only this can explain the known facts of terrorists blowing up their own RC devices when the power is turned on or when they are installed near powerful sources of electromagnetic radiation. In this regard, jamming unprofessional radio links instead of the expected effect of suppressing the control channel can lead to an explosion of ammunition. Therefore, the means and methods of combating radio-controlled explosive devices must not only be reliable, but also have a guaranteed predictable end result.

Let us consider possible methods of counteracting radio-controlled explosive devices. At first glance, it may seem that the problem of combating radio-controlled explosive devices is generally being successfully solved. However, such a conclusion is only valid in relation to the modern – first stage of radio-controlled explosive devices development. Currently, mobile (portable, less often – transportable) jamming transmitters are widely advertised as the main means of electronic counteraction. Most types of portable jamming transmitters have approximately the same technical characteristics. The operating frequency range is mainly from 20 to 1000 MHz and from 1800 to 1950 MHz. The power of a portable jamming transmitter varies from 3 to 25 W. To emit signals in such a wide range, two or three vertical electric antennas, most often asymmetrical vibrators, are usually used simultaneously. Unfortunately, such important characteristics of jamming transmitters as the unevenness of the interference spectrum are missing from advertising brochures. Many years of experience in operating such jamming transmitters have generally confirmed their effectiveness. However, the uncertainty associated with the ratio of control range and jamming, the power of the command and transmitting device of the radio line and the MPP, the choice of observation conditions and the transmission of control signals to the demolition man — significantly affect the radius of the safety zone, sometimes reducing it to a minimum.

Let us estimate in more detail the ratio of the signal and interference from the MPP at the installation site of the RUV. In accordance with the principle of extreme pessimism, we will accept the maximum possible power of the control signal transmitter of 5 W, the minimum distance of 200 m and the efficiency of the output power amplifier taking into account the antenna of 20%. Having carried out calculations using known methods, for example, using the ERM-73 radio wave propagation model [3], we find that with a ground-based location of the RUV transmitter, the expected electric field strength in the range of 30 … 150 MHz can vary from 2.6 to 13 millivolts per meter. Under the same conditions, when controlling from a building from a height of 30 meters, the signal field strength increases from 12 to 21 millivolts per meter.

Let us assume that the interference spectrum is uniform in the entire frequency range of the mobile jammer. Then the spectral power density of the interference in the 1 kHz band, provided that the mobile jammer has the same efficiency of 20%, taking into account the value of the antenna directivity coefficient equal to three, will be 15.3 μW. Without taking into account changes in the directional properties of transmitting antennas at high frequencies and accepting the assumption of their negligibly small length compared to the wavelength, we use the known formulas for calculating the field strength of a vertical Hertz dipole in the form [2] to determine the signal level:

. (1)

Neglecting the transverse component , inversely proportional to the cube of the distance between the transmitter and receiver, as well as the radial components, which received the designations respectively., , we will present the remaining components in the following form, taking into account the radiation along the Earth's surface:

, (2)

. (3)

Here is the unit vector of the vertical axis of the Cartesian coordinate system; is the complex amplitude of the current in the Hertz dipole; l is the length of the dipole; w is the angular frequency; r is the distance between the transmitter and the receiver; k is the wave coefficient; – absolute permittivity of vacuum; i imaginary unit. At distances of tens of meters, the influence of the soil on the reduction of the interference level can be neglected.

It is easy to see that these two components carry out the transfer of electromagnetic field energy in the form of wave processes. Each of them corresponds to its own component of the magnetic field strength , , associated with , the wave resistance of the medium. In addition, the ratio between the electrical components is:

. (4)

It should also be taken into account that between and there is a phase shift equal to .

The graph of the electric field strength at a frequency of 20 MHz in a receiver passband of 10 kHz is shown in Fig. 1.

 
Fig. 1. Dependence of the electric field strength of a mobile interference transmitter (dB) on the distance (receiver passband of 10 kHz)

Calculations show that the effect of the component of the electric field strength, inversely proportional to the square of the distance, is felt only in the low-frequency region of the interference spectrum at a short distance, not exceeding 5 … 10 meters. However, it cannot be neglected, since it becomes predominant at a distance of the MPP up to 1 … 2 meters relative to the radio-controlled explosive device.

The reliability of suppression of the control channel of the radio control system by noise interference depends significantly on the selected method of signal reception by the actuator. The typical dependence of the probability of signal reception on the ratio of the spectral density of interference in the 1 kHz band to the effective field strength of the signal when using frequency telegraphy for its transmission on the air is shown in Fig. 2.

Fig. 2. Typical dependence of the probability of reception of a control signal consisting of three elements on the interference/signal ratio

The graph shows (Fig. 2) that in order to suppress a three-element control signal of the control system with a probability of at least 0.001, the spectral density of interference in a 1 kHz band should exceed its level by more than 1.1 times. If, for example, the passband of the receiver of the actuator is 10 kHz, then the effective field strength of the interference in it should exceed the signal by at least 3.5 times. In this (worst) case, the range of reliable suppression of the control channel of the control system with a ground antenna can be 2.5 … 8 meters, and when raised to a height of 30 meters, it will decrease to 2 … 3 meters. Considering the sharp increase in the interference field level with decreasing distance, it can be assumed that when a mobile interference transmitter with a power of 25 W is located at a distance of no more than 1.5 meters from the installation site of the actuator, the control signal from any command and transmitting device used today will be suppressed with high reliability.

However, taking into account the multipath propagation of the signal in high-frequency wave ranges, changes in the orientation of the transmitting antennas when carrying the MPP, unevenness of the interference spectrum by frequency and other factors, the interference level may be insufficient precisely at the moment of emission of a short control signal. Note that the danger of injury to a protected person by an explosion of an explosive charge at such a short distance may be unacceptably high. The possibility of a non-professionally manufactured actuator being triggered by the interference itself should not be neglected. In addition, the voltage value at the input of the actuator receiver induced by interference from the MPP, which has mainly vertical polarization, may be further reduced in the case of orientation of the receiving antenna of the IP in the horizontal plane.

Let us dwell on an important drawback, inherent in principle to all interference transmitters, namely, the disruption of the operation of a large number of radio telephones, television receivers, service radio stations and many other devices that accidentally end up in the MPP coverage area. During its operation, interference will be created with an effective value of at least 100 μV/m in a 10 kHz band in a circular area with a radius of up to 130 meters, and at a level of 10 μV/m in the same band — already with a radius of up to 400 meters.

Thus, mobile noise jammers are the simplest, most reliable and relatively inexpensive means of counteracting radio-controlled explosive devices. However, when terrorists use powerful transmitters, as well as in cases of RCED control from a short distance, the radius of the signal suppression zone by interference may be insufficient to prevent the actuator from being triggered. In addition, the level of interference from the MPP created by outside communication facilities is unacceptably high, especially in urban conditions. Finally, we note the fact that mobile barrier jammers are an effective means only at the first stage of the development of radio-controlled explosive devices, when the actuator is triggered at a minimum distance from the target. When using target sensors, the signal to arm it can be sent in advance, when the target is removed by several tens or even hundreds of meters relative to the installed munition. In this case, mobile jammers become ineffective. Moreover, carriers of jammers can become an independent target for terrorists. To do this, it is sufficient to install a sensor for detecting a barrier interference together with the actuator, which causes the explosive charge to detonate when the MPP carrier approaches it at a minimum distance.

Are there other ways to combat radio-controlled explosive devices? The authors [1] gave a convincing, generally positive answer to this question, without rejecting any of them, but also without encouraging any probable prospects. The considered type of confrontation between RUV and MPP is just one of the many manifestations of the competition between the projectile and the armor, the skill of burglars and safe manufacturers, computer viruses and anti-virus programs in the broadest sense. The emergence of a new virus entails the improvement of software for combating them and vice versa. However, sooner or later there comes a moment when it becomes physically impossible to solve the problem of protection from a new highly effective munition by traditional means, increasing the thickness of the armor. Unfortunately, it should be noted that today there comes exactly such a moment when in the competition between radio-controlled explosive devices and countermeasures, the latter are still losing for the most part. The main reason for this is seen in the conceptual underestimation of the potential danger of this type of weapon.

Radio-controlled detonation of explosive charges as a widespread type of terrorist activity emerged back in the 1980s. The terrorists' accumulated experience of combat use of RCED in hot spots, supported by recommendations from foreign intelligence agencies, yielded rich results. Only in recent years, after catastrophic terrorist attacks, including those committed using RCED, terrorism as a phenomenon threatening the stability of the world community has attracted everyone's attention. That is, the awareness of the danger of large-scale use of RCED came with a delay of approximately 10-15 years. From that moment on, the problem of combating RCED ceased to be a task for intelligence officers only and became a common pain for the entire society. Commercial organizations, satisfying the emerging demand for electronic warfare, have developed a number of models for detecting and jamming RCED. However, the means of counteraction to radio-controlled explosive devices currently offered on the market are capable, for the most part, of performing only individual functions of detecting them in relatively simple conditions, as well as of protecting them with the help of the most destructive type of noise interference. In these conditions, at present, apparently, one cannot expect serious success in the field of combating radio-controlled explosive devices.

A successful solution to the extremely complex and important problem of combating RW, like any other, is possible only by combining the efforts of state and private organizations. Many years of practice have shown that it cannot be solved only by prohibitive or technical measures, even the most strict and perfect. It is necessary to take into account numerous aspects that contribute to increasing the effectiveness of measures to comprehensively combat this evil. We will list only the main ones.

1. The existing legislative framework in the area of ​​development and application of countermeasures against radioactive contamination needs to be improved. The manufacture of homemade radio links is carried out under legal prohibitions on this type of activity. However, underground developers are not embarrassed by the existing strict restrictions on the frequency ranges they select, transmitter power, modulation types and other parameters of radioactive contamination. In these conditions, it is necessary to clearly delineate the rights and obligations, permitted types of activity of state organizations, private security services and commercial firms in the development, production and operation of countermeasures against radioactive contamination. The emphasis should not be on prohibiting the creation and distribution of these means, but on their reasonable joint use in the common interests. It is very important to define the requirements for the degree of confidentiality of information on radioactive contamination, compliance with which, on the one hand, facilitates the exchange of opinions on all the most important issues in this area, on the other hand, guarantees its inaccessibility to illegal developers of radio links, and on the third hand, protects against the use of legally justified punitive measures in terms of non-disclosure of state secrets. There is an analogy here with the law on the rules for storing, carrying and using firearms, many provisions of which are now being actively discussed and require revision.

2. There is an urgent need to create a unified regulatory framework governing a set of technical requirements for means of counteracting radio-controlled explosive devices. This will allow the development and operation of modern models that guarantee the fulfillment of the functions assigned to them, to work out techniques and methods for their most effective use and to prevent low-quality products from entering the market, the only advantage of which lies in their attractive appearance.

3. It is necessary to create a single database of operational, analytical and scientific-technical information, generalizing all identified cases of the use of radio-controlled explosive devices, as well as prospects for improving RCEDs and countering them. Developers of RCED countermeasures from private companies should have access to open official information describing the appearance, design, technical characteristics, strengths and weaknesses of the studied radio link samples. It is necessary to determine the procedure for official access to this information in the presence of licenses, fulfillment of financial and other obligations.

4. It is necessary to create specialized training centers where professionals in combating radio-controlled explosive devices would undergo training, improve their qualifications, and share their experience.

5. Perhaps interested organizations will find it expedient to unite into a single association for combating radio-controlled explosive devices in order to combine efforts to improve the legal, regulatory, and information base, exchange opinions and technical achievements, and promote marketing and attract financial resources.

The listed measures pursue a single goal, namely, the unification of efforts in the specific fight against terrorism in its extreme form of manifestation. Only by creating a more powerful, effective and technically equipped structure than terrorist organizations can we count on success.

In conclusion, a few comments on some ways of combating radio-controlled explosive devices. Many years of experience have shown that their use can only be successfully counteracted by a set of coordinated organizational and technical measures. Proper organization of measures in terms of forecasting and preventing terrorist acts using RCEDs is quite effective in itself. First of all, it is necessary to teach security company operatives to detect and identify RCEDs by their characteristic telltale signs, forecast and monitor possible locations of actuators, locations of demolition men with command and transmission devices visually and using existing search tools: mine detectors, nonlinear radars, photography and other technical means. Periodically record changes in the situation, including electromagnetic, on the routes of movement of protected persons. It is necessary to avoid a pattern when moving: change speed, routes and movement order, choose the least visible routes for movement, avoid appearing in places with clearly visible landmarks near which actuators can be installed and use other specific measures. Naturally, due to the wide variety of external conditions of confrontation between terrorists and security organizations, in each individual case there is a list of effective measures to counteract the RUV.

Among technical measures, the problem of finding the places of installation of RUVs is currently and in the future coming to the forefront. It is necessary, in particular, to improve the methods of their recognition against the background of the terrain and false objects by technical means, for example, using additional private features of re-emitted signals of non-linear radars. Information about the places of recent installation of RUVs can be obtained using thermal imagers based on the temperature contrast of the actuator and the background.

It seems promising to continue developing the direction of counteraction to the RUV by means of radio interference. A promising method is the creation of interference with a discrete spectrum, which, as a result of its nonlinear transformation in the receiver of the actuator, creates a powerful interfering signal in the intermediate frequency channel. It is necessary to evaluate in more detail the possibility of creating and the effectiveness of powerful pulse interference on the reliability of suppression of the RUV control channel, including those induced in electric explosive circuits and on the elements of the actuator body, up to its guaranteed failure due to overload with a strong signal. This measure may be effective against unprofessionally manufactured devices. It is advisable to study the effectiveness of overloading the receiver path of the actuator with powerful directional radiation, leading to fatal distortions of the control signal. Although this method is of limited safety, since it does not lead to the failure of the actuator, it will allow you to move to a safe distance without the risk of being hit by an explosion of a charge of explosive. Finally, perhaps we should not completely reject the direction of creating portable stations of response radio interference consisting of a panoramic receiver and a transmitter of frequency-tunable narrow-band interference. Existing methods of fast Fourier transformation allow us to quickly determine at least a section of the range in which a powerful signal appears. Setting up a targeted barrage interference requires the use of a relatively low-power transmitter with the ability to work on a weakly tuned antenna.

It is also advisable to consider the possibility of emitting universal signals that cause premature operation of the actuators of the control system due to the reproduction of the control signal code. The effectiveness of this measure has already been partially confirmed by practice.

It may seem to the reader of these lines that the author, having no idea of ​​the complexity and degree of development of the ideas he proposes, is engaged in theoretical teachings. Not at all. The author is perfectly aware of how much effort, resources and time are required to test the operability or inoperability of this or that method of countering radio-controlled explosive devices. The thing is that, firstly, such hellish work is only possible for a powerful team with comprehensive assistance and support, primarily from the state, and secondly, it must be done in a comprehensive manner and in the shortest possible time. There is still time to complete this work.

Literature.

1. B. Iskhakov, V. Kargashin, L. Yudin. Problems of Combating Radio-Controlled Explosive Devices.//Special Equipment, No. 2, 2000.
2. V. V. Nikolsky. T. I. Nikolskaya. Electrodynamics and Propagation of Radio Waves. Moscow: Nauka, 1989. 543 p.
3. An Empirial Propagation Model (EPM-73). M. N. Lusgarten, and James A. Madison. IEEE Transactions on Electromagnetic Compatibility, Vol. EMS – 19, NO. 3, August 1977, p. 301 309.