TOR-M1 SAM SYSTEM:

 he introduction of newly developed capabilities to existing air defenses has markedly enhanced their effectiveness against assailant aircraft. To reduce losses, the intruder has begun to master the art of flying at low altitudes thereby making it more difficult for radars to locate air targets in good time on account of dead angles and increased errors caused by multipath propagation of the radio waves.
     The 1960s witnessed the development of new air defense systems intended to repel air raiders attacking ground installations from low altitudes. Russia developed the Osa (Wasp) complex, while Germany, in cooperation with France, came up with the Roland, and France alone, with the Crotale surface-to-air missiles (SAM).
     The detection means of these systems have many common design features due to such specific factors as the low angular rates of the targets relative to the radar system, especially in elevation. The effective range of the systems was selected depending on the possibility of detecting a target despite dead angles or hidden zones of about 0.6o caused by topography. Hence, preference was accorded to the low-altitude scanning zone with a ceiling of 3 to 5 km high.
     The algorithm of passover from target acquisition (performed by the target acquisition radar, or TAR for short) to tracking (performed by the target tracking radar, or TTR) comprised the following stages:
     1. Slewing the TTR antenna in azimuth to fall in line with the target position produced by the TAR.
     2. Starting the mechanical swinging of the TTR antenna beam in elevation in a manner enabling the beam to overlap the TAR error zone.
     3. Finding the site angle and completing the autotracking system in range and angular coordinates.
     Similar systems have successfully parried low-flying air raiders with effective radar cross-sections (RCS) of 1 m2 and more.
     In the 1970-1980s, several countries acquired airborne high-precision weapons (HPW), boasting improved quality and produced in increased numbers. In terms of effectiveness, the HPW could compare to tactical nuclear weapons, while they could be carried by both strategic aircraft and most flying machines represented by the army and tactical aircraft.
     At present, leading military specialists consider the HPW as the main weapon to deliver the first (preventive) strike, capable of disabling or paralyzing air defenses, increasing the capacity and enhancing the effectiveness of the conventional means of air attack. In the course of subsequent combat operations the HPW is used, as a rule, to destroy (neutralize) the vital pinpoint and small-size targets carrying important potentials.
     According to modern classification, the tactical HPW include:
     1. Antiradar missiles capable of destroying targets at a distance of 15 to 70 and, in perspective, up to 150 km from the launching point and flying at altitudes of 60 m to 12 - 16 km. The effective RCS of such missiles is minimized to about 0.1 m2, while the flight speed varies from 200 to 700 m/s.
     2. Airborne guided missiles with infrared, laser or TV homing heads, with a launching range from 6 to 10 km, angles of attack from 8-10 to 45-60 deg, effective RCS from 0.06 to 0.5 m2 and flight speeds from 200 to 600 m/s.
     3. Gliding and controlled guided aerial bombs and clusters with a release (drop) range of 8 to 10 km, effective RCS below 0.5 m2, speed of 250 to 400 m/s and angles of attack up to 50 - 55 deg.
     4. Missiles fitted with inertial guidance and terrain avoidance features using the terrain map and capable of flying at 60 m and lower altitudes.
     The HPW also include antiship missiles.
     Overall, the features that distinguish the HPW (or their destructive components) from other radar targets and offensive means alike are:
     - small effective RCS averaging in the forward hemisphere at 0.1 m2 for the centimeter waveband (1.5 - 5 cm);
     - wide range of angular rates and angles of approach to the objective of the attack: from level flight at an altitude of 30 to 60 m with terrain avoidance to angles of attack of 45 to 60 deg and more;
     - high cruising and maximum speeds of flight (200 to 700 m/s), variable values of such speeds (accelerated and decelerated flights) as well as high operational load factors reaching 8 to 10 g;
     - high mechanical strength of guided and controlled aerial bombs, reducing their vulnerability as targets.
     Such HPW features help them effectively withstand such systems as Osa, Roland and Crotale-NG. The first two circumstances impose new requirements on radars employed by the SAMs designed to fight the HPW, while the other two impose requirements on the flight ballistics and control loop of the systems as well as on the muscle of their combat equipment.
     The low values of effective RCS require huge expenditure of energy by both TAR and TTR, especially in case of electronic countermeasures undertaken by the enemy as well as the implementation of new procedures to seek out and track targets. The TAR must be either three-coordinate or capable of measuring the target angle of site to an accuracy that minimizes the fine search time by the TTR.
     The wide range of angles at which the HPW may approach the objective dictates the need for the TAR to shape an isodistant target detection zone instead of the isoheight (cosecant-squared) one widely employed by the SAMs, which is the main reason for the poor effectiveness of the existing SAM systems against the HPW.
     In addition, the TAR should realize the principle of criterional processing of the signals, thereby minimizing the level of false alarms, and also examine the target flight paths, categorize the targets, select the most dangerous ones from a group of detected targets and prioritize them. To solve these tasks, the TAR should incorporate a data processor with the required capacity.
     The TTR must ensure prompt lockon of one or several targets and automatically track the HPWs to an accuracy sufficient for their reliable engagement by SAMs at prescribed ranges.
     Meeting these requirements minimizes the system reaction time.
The following specific demands are imposed on SAMs intended to fight the HPW:
     (1) the missiles must be given a minimum possible time to be ready for launch (3-4 s);
     (2) the propulsion system of the SAM should ensure its most rapid acceleration (within 3-5 s) to the prescribed speed and support its powered flight to a range no shorter than the prescribed killing range of the HPW. The operational load factors of the SAM must allow it to hit the HPW with a g-load not less than 10 units;
     (3) the armament of the SAM must have sufficient power to destroy a highly strong HPW and allow the SAM to adapt to the type (class) of the target to be destroyed;
     (4) the cost of the SAM should be the minimum required to achieve the positive balance between the cost of the HPW (plus the cost of the prevented damage) and adjusted cost of the SAM.
     The general demands on a SAM system designed to fight the HPW are as follows:
     - the engagement range of aircraft that carries optically guided HPW must exceed the effective range of such weapons;
     - the reaction time, that is, the time elapsed between target detection and missile firing instants should be at a minimum. This can be attained via high automation of the battle performance based on extensive employment of computers (multiprocessor systems), elements of robotization and artificial intellect for maximum reduction of the crew workload;
     - the maximum cost-effectiveness criterion versus minimum cost of the SAM and reasonable (from the viewpoint of its significance) cost of the facility it protects;
     - the ability to combine the requisite number of SAMs into a highly automated system designed to defend the vital installations and main groupings of troops at the appropriate level.
     Russia's Tor-M1 SAM system is the world's first short-range air defense system specifically tailored for highly effective use against the HPW.
     The Tor-M1 SAM system has been developed and series produced by the Antey Concern. The system is a logical sequel to the OSA SAM family, capable of repelling existing and potential threats with the maximum efficiency.
     The core of the Tor-M1 SAM system is its combat vehicle (CV) whose main version is based on the cross-country tracked chassis of an intermediate weight category.
     The CV comprises:
     - TAR with a ground-based radar interrogator;
     - target and missile tracking radar (TTR);
     - backup TV optical tracker designed to autotrack targets in angular coordinates;
     - high-speed multiplex digital computer;
     - air situation display equipment, CV systems and means monitoring equipment, and CV commander and operator control panels;
     - coded radio command operational communications system;
     - navigation, survey control and orientation equipment;
     - surface-to-air missiles in group launching transporting containers (two containers with four SAMs in each);
     - primary power supply with the generator driven by the gas turbine engine or the engine of the self-propelled chassis;
     - auxiliary equipment.
     The Tor-M1 CV detects and selects air targets on the move and fires missiles at them from short halts.
     The antenna system of the TAR is stabilized. It produces an eight-portion radiation pattern (Fig. 2). The scanning interval is 1 s, the beam flare (width) in the vertical plane is 4 deg; the portion switchover (scanning) mechanism is electronic. Any three portions of the radiation pattern can be scanned within one scanning interval. The entire elevation zone covers 32 deg and can be scanned within 3 s. The regular scanning program is selected in such a way that, in order to increase the detection range for low-altitude targets, the first portion is scanned twice within three scanning intervals.
     To augment the TAR potential, the antenna system of the radar can be revolved mechanically through 32 deg with a detection zone of 32 to 64 deg. This means that two CVs of the Tor-M1 system can make up a detection zone of 0 to 64 deg, and the firing capabilities of each CV assure target engagement within 0 and 80 deg in elevation.
     To increase the pulse energy, the length of the emitted pulse is increased, and the pulse is internally modulated. The radar can also operate in an active jamming environment when the entire transmitted power of the radar is accumulated in one critical portion instead of being distributed among three portions.
     The receivers perform an automatic threshold and criterional processing of signals in digital form.
     To detect targets against the background of the earth's underlaying surface, atmospheric perturbations or man-made passive jamming, the TAR is provided with the moving target indication (MTI) feature assuring detection of both high- and low-speed (up to 10 m/s) targets without "blind" speeds. The MTI system has two rejection zones allowing simultaneous suppression of both the clutter and moving passive interferences.
     After their first (coarse) cessing, the signals are fed to a computer where target track initiation is performed. The most dangerous threats are identified by their minimum approach flight time, altitude and crossover range. This information is then used to designate the targets for the TTR. The accuracy of target designation is 100 m in range, 20 min in azimuth and 2 deg in elevation.
     The main characteristics of the TAR and zone for detection of a target with the effective RCS equal to 0.1 m2 and detection probability p = 0.5. The radar has a detection range of 18 to 22 km, which is sufficient to engage air targets (depending on their speed) at ranges from 12 km and less and within virtually all elevations (up to 64 deg).
     The TTR of the Tor-M1 SAM system is of the pulse Doppler type capable of determining four coordinates of the selected target. To assure steady passover to autotracking of point targets and obtain highly accurate target coordinates, the radar uses a high-powered pulse transmitter.
     To reduce the time required to switch to the autotracking mode and materially weaken the influence of the motion of the target on its lockon, the TTR uses a phased antenna array (PAA) with a small number of elements, which deflects the antenna beam at a level of 3 dB within ñ7.5 deg. The fine target search is then accomplished through electronic deflection of the antenna beam within 7 deg in elevation and 3 deg in azimuth. With the selected accuracy of the target designation received from the TAR, the fine search limits assure 100-percent target lockon. The time required to switch to autotracking ranges from 400 to 600 ms, depending on the target speed and interferences. With this passover time, the target seems to be "frozen" with respect to the scanning sector of the PAA, ensuring the high reliability of the switch to the autotracking mode. The TTR uses the Doppler signal processing, pulse compression, fast Fourier transforms, and narrow-band filtration, which, when combined with the high-energy pulse, large gain of the PAA and low level of its sidelobe and background noise, makes the TTR highly immune to jamming.
     The Tor-M1 SAM system uses a TV optical tracker, which autotracks target angular coordinates, as a backup tracking system.
     The missile armament is used effectively by discriminating between target types. The TAR allows discrimination between four classes of targets: point targets (or HPW), airplanes, helicopters and unidentified targets. This results in increased probability of engagement of small-size targets, notably HPW.
     To track missiles, the TTR has two channels. One of the channels serves to lock on to and track the missile by using beacon signals at the starting leg of the flight. The second channel uses the missile responder signals received via the PAA to track the missile throughout its flight path.
     The commands are transmitted to the missile by the radar transmitter via the PAA. The indicator equipment, incorporating a commander's target flight path display, TTR target and missile tracking displays, a TV tracker video monitor, TAR operator displays, control panels and signalling devices, are brought onto a single console located in the CV operator compartment. The seat of the driver-mechanic, who drives the CV, starts and monitors the operation of the gas turbine driven power supply unit, is also located there.
     In terms of shape, the Tor-M1 missile is of the canard type. It is launched vertically to a height of 15 to 20 m with the aid of a powder catapult and is then inclined by a special thruster towards the target, and its main solid propellant rocket motor takes over.
     The motor of the missile is single-stage and two-mode. In the launching mode, the motor accelerates, within four seconds, the missile to a maximum speed of 850 m/s; in the cruising mode, which lasts for 12 seconds of flight, it maintains the above speed. This makes for the required power-to-weight ratio of the missile, allows the missile to cover a distance of 8 km in powered flight and effectively engage targets flying at speeds below 700 m/s and g-loads up to 10 g.
     The missile is furnished ready for use inside a launching transporting container designed to accommodate four missiles.
     One major characteristic of the short-range missile systems is the reaction time or the interval between the moment of target detection by the TAR and the instant of missile launch. One can single out three characteristic stages in the process:
     - detection of targets by the TAR, their processing and track initiation, establishing priorities according to the relative threat criterion, and production of target designation data for the TTR;
     - orientation of the antenna post towards the most dangerous target in azimuth and elevation;
     - fine search of the target, switchover to autotracking and missile launch.
     The total reaction time of the Tor-M1 SAM system changes from 3.4 to 10.6 s, depending on the employment conditions and intensity of interference. When employed on the move, the two seconds required to stop the CV are added to this time. It should be stressed that the high degree of battle performance automation, employment of artificial intellect and unique algorithms make it possible to perform all the operations, involving detection of targets and the switch to autotracking the two most dangerous ones, virtually without operator intervention.
     Four Tor-M1 SAM CVs are organic to one SAM battery, which is the smallest tactical subunit capable of executing combat missions independently. To control the combat actions and fire of the CVs, each SAM battery has an automated battery command post (BCP). Using the coded communications and navigation, survey control and orientation equipment of the CVs, the BCP produces target distribution and precludes accidental concentration of fire of several CVs on one target. The essence of target distribution resides in the automatic exchange of information on autotracked targets among the CVs via the BCP and automatic reassignment of priorities by the CVs with corrections made for received information. The target distribution system realizes the step-by-step principle of adaptation of the CVs to the current air situation in real time. When necessary, the battery commander may intervene into (correct) the target distribution process and execute other combat control tasks.
     Furthermore, the BCP can receive and display the current air situation (10 most dangerous targets) from one (any) subordinate CV and from the TAR located at a higher command post (CP) and establish operational communication inside the SAM battery and with the higher CP.
     The entire process of control over the Tor-M1 SAM system CVs can be realized when all the elements of the SAM battery are on the move or brought to a halt. The BCP also integrates the SAM battery or a local system organized around it into the general structures of the air defense systems of a large unit or region of the country.
     In addition to these combat means, the Tor-M1 SAMs are provided with transloaders, maintenance trucks and mobile SPTA sets.
     Overall, the short-range SAM systems form an important component part of air defense units protecting installations and troops in most states in the world. The combat experience gained in recent local wars and conflicts lends support to the need to establish and continuously upgrade the SAMs now in service with motorized rifle divisions. The lack or shortage of modern SAMs in the air defense systems of present-day motorized rifle divisions leads to heavy losses or other serious consequences inflicted by enemy air attacks and the wide-scale employment of airborne short and medium-range HPW.
     Today and for the foreseeable future only one system is capable of fully meeting the present-day requirements placed on the SAM systems of motorized rifle divisions: the Russian-made Tor-M1 SAM.
     Moreover, it should be pointed out that to date the Antey Concern has come up with truck-and-trailer, trailer and container versions of accommodating the Tor-M1 SAM system components (antenna/launcher, display equipment and power supplies) on various movers to cover vital point and small-sized installations.
     In this case the basic combat and operational characteristics of the mobile SAMs (Tor-M1P) are retained at the level of the basic (self-propelled) version, but the former may cost 30 percent less than the basic version. In addition, the mobile versions of the Tor-M1P SAM system offer more comfort to the crew seated in the display equipment compartment and make them less vulnerable in combat, as the display equipment compartment may be arranged in a shelter at a distance of 50 m from the antenna/launcher assembly.
     On customer request the basic version of the Tor-M1P SAM system may be developed into local highly automated systems to protect vital point and small-sized installations, which may subsequently be integrated into the unified air defense system of a region (country).