Perimeter TSO: selection features.

Perimeter TSO.

The variety of types and industrial samples of perimeter technical detection equipment poses the question of their correct selection to the facility management and security services based on the security requirements and conditions at a specific facility.

Often, a contractor designing and installing security systems tends to offer only the types and samples of TSO known to him.

But the proposed means may not always meet the requirements of the facility management, based on the threat models of intruders.

Therefore, managers need to have complete information about these means.

Perimeter TSOs are based on a variety of physical principles and types of sensitive elements (SE) that perceive the impact of intruders when crossing their sensitive zones (43).

They can be one of two main types. When choosing perimeter TSOs, it is necessary to take into account:

• perimeter protection tactics;

• conditions in the perimeter zone of the facility:

• methods of possible actions of the categories of violators taken into account;

• financial capabilities of the customer.

Perimeter protection tactics

Perimeter protection tactics can be open and covert.

Open tactics assume the absence of special measures to covertly place the TSO.

In this case, means are used that have characteristic visually recognizable sensitive elements.

For barrier TSOs — these are special structures of the fence canvas or canopy, fixed to the fence canvas or canopy, cables and sensors, junction boxes.

For other TSOs — these are characteristic transceiver racks, a system of wires, etc.

With open defense tactics, a potential intruder sees that the perimeter is well fortified and may refuse to prepare and carry out his action. A «purposeful» intruder, however, will naturally try to bypass the sensitive areas of the TSO.

Secret tactics require the use of TSO, whose sensitive elements are either not openly visible or are disguised as local objects.

The greatest secrecy is provided by passive TSO without characteristic radiation into space, which can be detected by special devices.

Of course, when choosing this tactic, one should take into account the complexity of ensuring the secrecy of the TSO on the perimeter, associated with the generally higher cost of covert TSO and with additional, often very significant, costs of camouflaging the TSO, as well as the need to take organizational and other measures to prevent information leakage from the facility personnel, which will negate all measures to ensure the secrecy of the TSO.

Table 1. Types of perimeter TSO

Conditions for installing TSO in the perimeter zone

There are two groups of conditions for installing TSO in the perimeter zone:

1) conditions determining the possibility of installing certain types and models of TSO:

2) conditions affecting the resistance of TSO to false alarms. The first group of conditions is characterized by:

•the presence or possibility of constructing an external capital fence of the facility:

•the presence or possibility of allocating an alienated zone for the placement of TSO on the perimeter of the facility and the permissible width of such a zone;

•the configuration of the perimeter zone: the number and sizes of straight sections;

• terrain relief in the perimeter areas: the presence and size of slopes and unevenness, the possibility of planning and leveling the areas;

•the presence of vegetation in the perimeter zone: trees, bushes and tall grass (with data on the density and height of the vegetation), the possibility of removing it completely or partially, as well as organizing periodic work to clear the area.

Here, obvious aspects of taking into account restrictions on the climatic performance of TSO samples, which are essential for objects located in special climatic zones, are not specifically considered. These conditions when choosing TSO are of the nature of primary restrictions. It is convenient to present the factors and the data characterizing them in the form of tables with columns «Condition» and «Characteristics», and in one table enter the data generalized for the entire perimeter zone of the object, in the other data for each of the perimeter sections. The second group of conditions is characterized by:

• the possible frequency of wind disturbances, average and maximum wind speed and gusts, prevailing wind directions;

• the possible frequency of rain, snow and their average and maximum intensity;

• the possible frequency of thick fog;

• the presence in the vicinity of the object and the possibility of appearance in the perimeter zone of: large animals (cow, elk), medium-sized animals (large dog, wild boar), small animals (fox, hare), as well as the frequency of such appearances;

• the presence in the area of ​​the facility and the possible frequency of appearance and flight in the perimeter zone of the TSO of small and medium-sized birds;

• the presence near the perimeter zone of sources of seismic disturbances: operating mechanisms, roads and railways, etc.;

• the presence near the perimeter zone of sources of electromagnetic interference: power lines, powerful radio stations, electrical installations, etc.

The presence of an external capital fence creates the possibility of using a barrier TSO as the first external line of defense. It is necessary to specify the type of fence that is available or can be built on the perimeter of the object: brick, concrete slabs or chainmail mesh. Considering that unauthorized persons have free access to the external fence and can act on it without the purpose of overcoming it, causing false alarms of the TSO, it is advisable to use TSO with canopy versions of the SE on the external fence. At the same time, access of random persons to the SE should be difficult. It is possible to use a TSO that blocks the internal zone immediately behind the fence.

The use of an external capital fence not equipped with a TSO does not make much sense from a security point of view, since it allows an intruder to prepare and overcome the physical barrier for as long as he wants using any improvised and special means and methods.

Elements of blocking and delaying intruders

In general, all physical barriers can be divided into blocking elements and elements that delay violators.

A blocking element is a barrier that prevents the penetration of violators of the categories considered below.

For example, stationary anti-ram barriers such as concrete blocks prevent violators from overcoming them in vehicles.

A capital wall of a building or premises prevents the penetration of violators who do not use methods and means of destroying walls.

The perimeter fence is an element of intruder delay, so it must be equipped with a detection device, otherwise the fence will only play the role of designating the boundary of the object and a barrier for strangers and animals.

Passive external fences require additional costs, so they are advisable mainly for especially important objects.

Based on the analysis of the external fence and the perimeter zone of possible placement of the TSO, the options for the perimeter complex of the TSO are determined: the required number of detection lines, types and kinds of TSO for each line.

Intruder models

The methods of possible actions of the categories of intruders taken into account are determined in the intruder model, which must be formed for each facility.

Such models are developed by security service specialists, who, if necessary, involve representatives of the Ministry of Internal Affairs and the FSB, and must be approved by the heads of the facility or a higher-level organization.

The model determines:

• categories of violators:

• goals that violators of each category may pursue:

• the nature of their awareness:

• level of training:

• equipment.

In addition, the model should define the most complete list of possible options for the methods of action of violators at each stage of the action, including methods for overcoming the boundaries of perimeter TSOs, at which violators should be detected.

Functional characteristics of perimeter TSOs

The main functional characteristics of perimeter TSO are the reliability of detecting intruders and resistance to false alarms (FA).

It is primarily by functional criteria that the types and samples of TSO should be compared and selected.

The quantitative indicators for functional criteria are the probability of detecting intruders and the frequency of false alarms.

The detection probability and false alarm rate are directly related: the detection probability of a specific TSO sample is increased by lowering the detection threshold of useful signals against the background of interference, which leads to an increase in the false alarm rate. Conversely, a decrease in the false alarm rate leads to a decrease in the detection probability.

As research and practice have shown, the probability of detecting violators by a specific type of TSO is primarily affected by the way intruders overcome it, and the frequency of false alarms of TSO is affected by the type of external disturbance factor that affects the SE and the formation of an interference signal.

It is potentially possible to achieve an improvement in these indicators or one of them with a fixed value of the other by implementing complex signal processing algorithms that recognize useful signals against the background of interference (analysis of the fine structure of signals).

On the one hand, the multivariance of intruders and the nature of their actions when overcoming the TSO, and consequently, the forms of useful signals at the output of the SE, on the other hand, the no less enormous diversity and irregularity of interference effects on the SE of both natural and artificial origin make the problem of creating a TSO with two high functional indicators very complex.

Today, the solution to this problem for specific types of TSO remains the subject of research and development.

Selection of TSO

The selection of TSO can be carried out in stages: at the 1st stage — by types of TSO and at the 2nd stage — by samples of TSO available on the market.

This article considers the procedure for selection by types of TSO as a methodological example. A similar procedure can also be used for selection by samples.

Selection by types assumes the validity of the assumption that the probability of detecting violators for a certain type of TSO is associated with the type of method for overcoming the TSO by the violator, and the frequency of false alarms — with the type of disturbing external factor.

This assumption, in particular, is used in computer models for analyzing the vulnerability of objects that are widely used abroad.

Potentials for detecting intruders and false alarms

To select the types of TSOs suitable for an object, it is convenient to use qualitative point estimates of the indicators of detection reliability and resistance to false alarms, which we will call detection potential and false alarm potential, respectively.

For detection reliability, we use the following gradations of detection probability:

• 5 — very high (at the level of 0.98 and higher):

• 4 — high (at the level of 0.95):

• 3 — average (at the level of 0.9):

• 2 — below average (at the level of 0.7-0.8);

• 1 — low (below 0.7).

Similar gradations are used for the false alarm rate (without specifying specific levels):

1 — very low LT rate:

2 — low:

3 — average:

4 — high:

5 — very high.

Table 2. Detection potential of perimeter TSO for intruders

Table 3. Potential for false alarms of perimeter TSOs

Table 4. Methods of overcoming perimeter TSOs by violators

This data should be treated critically, given the year of publication (Defence. 1982. Vol. 13. No. 6).

Specific data on the characteristics of TSOs presented on the Russian market are, as a rule, confidential and are not openly distributed.

Due to the use of foreign data, Table 2 only provides some types of TSOs and methods for overcoming their violators.

A more complete list of methods for overcoming the TSO by intruders, which should be taken into account when choosing, is presented in Table 4.

Similarly, a more complete list of conditions affecting false TSO alarms is given in Table 5.

As a rule, the method of overcoming by air requires separate consideration, since in this case intruders are not detected by non-covert perimeter TSO (this is when it is advisable to use covert TSO).

Table 5. Factors Affecting False Alarms of TSO

The presence of several values ​​of detection potential, indicated in Tables 2 and 3, means that there are both different sub-options for overcoming TSO by violators in this way, and variants of samples of this type of TSO.

It should be noted that the total detection potential of various types of TSO in Table 2 was determined without taking into account the weighting factors of the methods of overcoming them by violators.

That is, in essence, the probabilities of each method under consideration were assumed to be equal.

At the same time, weighting factors, subjective probabilities of overcoming methods, can be determined at each facility. These probabilities should be determined by experts, for example, using point estimates for each method and subsequent calculation of probability coefficients.

The experts should primarily be the facility managers and security service as decision makers.

During the examination, they should personally participate in the formation of the intruder model and analyze the obtained selection results. Similarly, the weighting coefficients of the factors influencing the false alarms of the TSO can be determined.

These weighting coefficients are calculated as the relative shares of the time of action of each factor to the total time of action of all factors taken into account during the year.

It follows from Table 2 (keeping in mind the demonstration nature of the example using data from only one source) that barrier TSOs have a detection potential of approximately the same level. But it should be taken into account that electromechanical TSOs are not used in Russian climatic conditions due to the extreme complexity of ensuring operability.

Of the other types of TSOs, TSOs based on magnetometric, television, and LWV have the highest detection potential.

This is an obvious consequence of the volumetric sensitive zone of the TSO, bypassing which is difficult for an intruder.

From Table 3 it follows that according to the potential of the LT, without taking into account the probabilities of occurrence of factors in the conditions of the object, three groups of TSO are distinguished:

1) vibration TSO and TSO based on LWV, which have the lowest potential;

2) capacitive, radio beam TSO, which have a slightly higher potential:

3) optical-electronic TSO — IR-passive and television, which are most susceptible to interference factors.

The specific functional potential of the TSO in the form of the ratio of the specified potentials, multiplied by 100 for ease of presentation, can serve as an indicator that takes into account both the detection potential and the LT potential of the TSO.

Table 6 presents the values ​​of the specific potential obtained from the data in Tables 2 and 3.

Table 6. Specific functional potential of perimeter TSO

Thus, the selection of perimeter TSO for specific objects is a rather complex task.

Application of the procedure for calculating the detection potentials and false alarms for types and samples of TSO is one of the approaches to solving such a problem, providing good initial information for analysis, comparison and selection of perimeter detection means.