Classifications, features and information-measuring models of detection equipment.
Classifications, features and information-measuring models of detection equipment.
ZVEZHINSKY Stanislav Sigismundovich, Doctor of Technical Sciences, Associate Professor,
IVANOV Vladimir Anatolyevich, Candidate of Technical Sciences, Associate Professor,
RUDNICHENKO Valery Aleksandrovich
One of the current areas of development of technical security means (TSM) is the systematization and unification of the existing methodological and terminological apparatus. The differences that have appeared since the times of the USSR were caused by the departmental disunity of the two main state structures dealing with technical problems of facility security — the Ministry of Internal Affairs and the Ministry of Medium Machine Building (now the Federal Atomic Energy Agency). It is enough to mention such terminological collisions as «perimeter — perimeter», «detector — detection means», etc. Unfortunately, the confusion has not only not been eliminated to this day, but continues to grow — there is no single GOST, various departmental OSTs and technical guidelines continue to be issued. This is due, among other things, to the expansion of the nomenclature and the emergence of new types of products, the entry into scientific circulation of translated foreign publications, where the «difficulties in translation» only increase entropy. Foreign terminology, “images,” and even mathematics often “fit” poorly into the Russian language; for example, in English there are three concepts of “false alarm,” each with nuances that are difficult to understand [1]. The number of publications on reducing confusion in terminology is extremely small; they can really be counted on the fingers of one hand [2].
The same applies to various classifications of TSO products and, above all, to detection means (DM), as the most diversified class of special equipment. In technical literature, there are various classifications of DM intended to record the fact of an unauthorized crossing of a protected boundary of an object by an intruder, or his intrusion into a protected zone [1,3-6]. To a certain extent, they are interconnected, but there are also significant differences. — in foreign literature, it is customary to divide DM, first of all, by the tactics of application. For example, fiber-optic DM are divided into two subclasses — those installed in the ground (i.e. seismic) and on a «mesh» fence (fence), although in essence of signal formation they are practically no different from each other [1]. On the other hand, even developers sometimes find it very difficult to grasp the technical difference between such terms as capacitive, electrostatic and “E-field” COs that appear in the literature [1,3].
In this regard, an attempt was made to classify the detection devices that would, if possible, be consistent with the available information, and on the other hand, more accurately characterize the products by their operating principle. The criterion «type of interaction of the detection device with the intruder» proposed in [6], supplemented and clarified, was chosen as the main dividing rule. In essence, this is the principle of signal formation, showing how (by means of what) the detection object causes a registered change in the physical quantity in the detection device.
Any security system generally consists of two parts — a sensitive element (SE) and an electronic unit (EU). The SE forms a detection zone (DZ) around itself — a region of space, the intrusion of an intruder into which causes an electrical useful signal (ES) at its output. The EU perceives the signal from the SE, amplifies, filters and processes it according to a specific algorithm in order to distinguish ES from various interferences caused by various natural, climatic and industrial factors. If the algorithmic features are satisfied, then binary «alarm» signals appear at the EU output, which with a high probability indicate the fact of a violation; the number of signals characterizes the classification features of the intruder, which are detected by the security system. For example, it can be the direction of movement (away from us, toward us), type (single, group, vehicle), etc. Signals via a communication line (wire, radio) are sent to the information collection and processing system (ICPS), where a decision is made on the veracity of the event and adequate measures to detain the offender.
ICP is a complex technical device, an information and measuring system for pattern recognition (of offenders and sources of interference), which matches the input signals (respectively useful or interfering) with output binary signals (like «yes»/»no»). Fig. 1 shows its generalized information and measuring model.
First of all, it is important to divide all seismic detection systems into 2 large classes: passive and active [3]. Passive means detect an intruder by recording changes caused by it in the existing physical field, environment or substance. For example, magnetometric seismic detection systems are based on recording changes (of the order of 1 nT) in the Earth's magnetic field (the main constant component is about 5 x 104 nT) caused by the intrusion of a ferromagnetic mass characteristic of an intruder (e.g. weapons, household items, vehicles) into the seismic field. In this case, the signal transmission medium (air, soil) does not have any effect on the seismic receiver due to its diamagnetic properties. In passive seismic seismic detection systems, the vibration energy from the impact of an intruder on the Earth's surface, perceived by the seismic receiver, will be significantly weakened and transformed by the environment — soil. However, in both cases, the principle of interaction between the SE and the intruder is the same. passive.
Active means detect an intruder by registering changes caused by him in a specially created physical field, usually electromagnetic. Such a field is excited in space, usually by a transmitter (PRD), and is detected by a receiver (RRM). For example, two-position radio beam SS are based on registering changes in the power of a high-frequency electromagnetic field received from the transmitter by the receiver, caused by the intrusion into the ZO of an intruder with a certain effective scattering (radiation) area.
Figure 1 — Generalized information-measuring model of the SO (PRD — transmitter, RRM — receiver, for active means)
Fig. 1 shows the information characteristics describing detection objects, undetectable objects — interference sources, the environment for signal propagation and generation, as well as the main parts of the detection system — the SE, the analog processing circuit, and the digital processor. The most important information link (chain) in this model is the detection object — the environment — the SE, where the formation and transformation of the initial information into a useful signal occurs. This link formed the basis for the classification of types of detection systems by the principles of signal generation, shown in Fig. 2. Further clarification of the types can be based on less significant differences, for example, for vibration — this is the type of SE: distributed or point, combined into a line [7].
Figure 2 — Classification of detection equipment based on physical principles of signal generation
It should be noted that the classification of the SI according to Fig. 2, like any other existing one, is not complete, but only reflects, in our opinion, the most important function implemented in the SI — extraction and transformation of information through the interaction of the object with the SE through the environment. Other important classifications of the SI can be: by application tactics, by the nature of the detection zone (Fig. 3), their features are covered, for example, in [1, 3].
Figure 3 — SI classifications by application tactics and the nature of the detection zone
The class of quasi-passive SS highlighted in Fig. 3 includes such rare products (primarily fiber-optic), where the active field circulates in a strictly limited volume (for example, fiber optics, waveguide), and cannot be registered by field scanners used by trained intruders to bypass detection zones. As practice shows, the most important classification according to Fig. 3 is the division of SS by application tactics into barrier, non-barrier and camouflaged.
Summarizing the known data [1,3-5,8] and based on our own experience in developing and operating surveillance systems, Table 1 provides comparative capabilities of various surveillance systems types and kinds to detect 12 of the most common models (types) of human intruders. A dash indicates that the system is not intended to detect these types of intruders. Table 1 does not consider such «exotic» intruder models as hang gliders, parachutes, high «stilts», etc. The table shows that there is no single universal surveillance system that is best suited for all situations. Among barrier surveillance systems, the maximum «detection potential» [4] is possessed by surveillance systems based on taut wire lines (taut wire), among non-barrier surveillance systems — lidars, among camouflaged surveillance systems — surveillance systems based on the leaky wave line (LVL) effect.
Table 1 — Comparative potential of types and kinds of detection means for detecting intruders
Table 2 presents data on the comparative noise immunity of detection equipment types to the action of various noise factors, as well as their inherent shortcomings. In general, the most significant ones include large animals and the effect of strong wind, which directly or indirectly affects almost all types of detection equipment. In general, it can be noted that, in terms of the totality of all significant interference, active detection equipment is more noise-resistant than passive detection equipment. The greatest «noise immunity potential» in the absence of migration of large animals is possessed by fiber-optic, electrical contact, two-position radio beam detection equipment, and when exposed to animals — magnetometric detection equipment.
Table 2 — Comparative table of susceptibility to interference for detection means (external, perimeter)
Thus, the proposed classification of detection means by signal generation principles allows, in the authors' opinion, to correctly discriminate between known products by assigning them to two large classes: active and passive. An additional classification by application tactics and detection zone type allows dividing detection means into three other classes: barrier, non-barrier, and camouflaged. The identified advantages and disadvantages of detection means types and kinds give grounds for asserting that there cannot be a «universally» good product, since any physical principle is not globally optimal.
Literature
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