Nonlinear locator is an effective means of ensuring security in the field of information leakage.

Non-linear locator is an effective means of ensuring security in the field of information leakage.

Non-linear locator is an effective means of ensuring security in the field of information leakage.

Dr.Sc. N.S. Vernigorov

Director of NPP «Vikhr»

The rapid development of non-governmental security services (SB) has led to a real boom in the market of special technical means and services. A certain share of this is occupied by audio information recording devices, the most covert, and therefore less vulnerable in terms of their timely and rapid detection. Radio microphones occupy a large part of the spectrum of information recording devices. There are two main methods for their detection, known to specialists in the field of electronic countermeasures: passive detection (this method includes monitoring the radio airwaves using available receiving equipment) and active detection (this method includes detection of objects using location). If the first method is known to almost all SB specialists, the second until recently was «terra incognito». This article discusses the principle of active detection and the main parameters of locators for detecting electronic devices.

The ability to detect radio-electronic objects using a locator is based on the physical property of semiconductor devices, which consists in the fact that when they are irradiated with a probing signal, the signal frequency is converted into multiple harmonics with their subsequent emission into the air. In this case, the conversion process does not depend on the state of the irradiated radio-electronic device (active — on or passive — off). Reception by the locator of any higher harmonic of its own radiation unambiguously establishes the presence in the probing zone of a radio-electronic product of any functional purpose and in any camouflage.

Development of non-linear locators began in the USA, Great Britain and the USSR in the mid-1970s. The first device to enter service with the CIA was the Super Scout locator, serial production of which began in 1980. In 1981, the British Broom locator appeared, which was somewhat inferior to its American counterpart. The domestic locator appeared in 1982 and was called Orchid. Unlike foreign counterparts, domestic developments went in a slightly different direction, as a result of which Orchid sharply surpassed foreign counterparts in its tactical and technical characteristics (TTX), and its weight and size were 2 times smaller.

Currently, the domestic market offers a wide range of both domestic and foreign nonlinear locators, the main ones of which are listed in the table. When choosing a model, the main attention should be paid to the following locator parameters: radiation power, radiation mode, radiation frequency, and the presence of a certificate for use for the stated purpose. Radiation power has two aspects: it increases the TTX of the locator and is a health hazard for the operator.

The radiation mode is directly related to the radiation power. In case of continuous operation of the locator, the maximum radiation power reaches 3-5 W. This means that the average radiation power to which the operator is exposed during operation at frequencies of 880-1000 MHz (the range of operating frequencies in the models) is very high and is a source of danger during long-term operation. With pulsed radiation, the power in the pulse reaches 300 W, but the average power is very small. For example, in the Cyclone series locators, the maximum average power is only 0.12 W, in the Oktava locator — from 0.45 W to 1.5 W.

Radiation frequency. This parameter, along with the radiation power, is fundamental for the performance characteristics of the locator. This circumstance is associated with two factors: the frequency dependence of the attenuation of the power value in the propagation medium of both the probing signal and the signals at higher harmonics (an exponential increase in attenuation is observed depending on the frequency); due to the physical nature of the frequency conversion process by semiconductor devices, the power level of the converted signal is higher, the lower the frequency of the locator. Consequently, the performance characteristics of the locator increase significantly with decreasing frequency.

When choosing a locator model, the question of registering, in addition to the second, also the third harmonic arises. The need to register the third harmonic is caused by the alleged possibility of selecting electronic products and metal contacts or rusty parts in reinforced concrete structures. However, it should be noted that registering the third harmonic does not guarantee (even by 30%) the selection effect. According to the physical principle of signal conversion, radio electronic devices emit not only the second, but also the third harmonic, and in most cases its level is much higher than from metal contacts. In addition, due to the same physical principle, when the ambient temperature changes by only 1 degree the level of the third harmonic from electronic devices increases by 1.2 times. Thus, depending on the temperature in the rooms being examined, this parameter changes significantly and it is not possible to identify it by simply recording two harmonics. There is a special technique for this, but its consideration is beyond the scope of this article.

The need for certification documents for non-linear locators is due to the following factors. Firstly, according to the law, when commissioning a transmitting device with such power values, permission to allocate the operating frequency of the transmitter is required. Secondly, when allocating a frequency to the locator, it is tested for a specific declared purpose, as a result of which a full cycle of measurements is carried out for the permissible radiation level for the safety of others and service personnel. Technical conditions are agreed upon with the State Telecommunications Inspectorate of the Russian Federation. ‘

An additional parameter characterizing the performance characteristics of the locator is the detection characteristic. If we talk about the detection range, as is customary in location in general, then this characteristic is standardized only for free space. In the conditions of searching for hidden electronic devices indoors, we should not talk about the range, but about the maximum depth of detection of objects in a masking environment. For indoors, this parameter is the maximum thickness of building structures at which the object is detected.

As for specific data on the detection capability of the main models of locators, there is no information on any product except for the Cyclone series. Models of the Cyclone series detect electronic devices in reinforced concrete walls 50 cm thick, and in brick and wooden walls 70 cm thick.

Referring to the table of locator models offered on the domestic market, we can make the following conclusion. Foreign locators have not changed in their performance characteristics since 1980. Only the latest models of «Diviner» and «Armashield» have decreased in weight and dimensions. The domestic locator «Ob» is a complete analogue of foreign ones.) The rest of the domestic locators are pulsed, but differ in their TTX. We will especially note the locator «Cyclone». This model is intended for two functional purposes. The first is traditional — use in search mode. The second is use in guard mode. In this mode, two locator antennas are installed in the passage of the controlled area, as a result of which it is impossible to bring or take out any radio-electronic devices or their components into this area, wherever they are located on the human body or in hand luggage. This makes it possible to implement an additional security barrier against penetration into this area of ​​both data collection devices and explosive devices with electronic detonation control. There is no non-linear locator with such functions in world practice.

As for the importance of using a non-linear locator in the practice of security services, at present this is the only technical means, the use of which guarantees 100% quality of inspection of premises to identify hidden electronic devices of any functional purpose.

The author hopes that he managed to answer all the main questions that arise in the process of choosing a model in a short article, as well as explain the basic principle of operation of a non-linear locator.