The successful use of the Polish “Grom” MANPADS against the Russian air assets in Georgia, and the lethality of the “Piorun” system proven in Ukraine are a result of the development of an entirely new generation of seekers in Poland. Every new iteration of these seekers becomes increasingly more effective and resistant to countermeasures and interference, and they reach levels of advancement unachievable for most of the competing designs.
The development of the Polish MANPADS seeker units takes place primarily at Telesystem-Mesko. The latest products by Telesystem, readied for commissioning in the Polish Armed Forces, include the GSNWK multi-spectral seeker, and the IIR EO-tracking unit. The former product may create a foundation for the introduction of new generation MANPADS systems, and short-range (10-12 kilometres) anti-aircraft missiles, designed now as "Piorun+" or "Grzmot".
Meanwhile, the imagery-tracking unit may become the inception point for a whole array of missile systems that could detect and identify threats based on the existing database, and thus be able to select the impact points that would be most exposed and sensitive.
GSNWK Multispectral Seeker
GSNWK Multispectral Seeker is designed for anti-aircraft missiles that, by design would be able to detect and track targets with low emission levels, such as helicopters with heat shields, or UAVs. Three-detector coordinator with a fairing is the key component here, featuring argon-cooled detectors for two IR bandwidths, and a UV spectrum, fitted with pre-intensifiers.
That coordinator unit tracks the target, automatically aligns the gyroscope's optical axis with the missile-target vision line, and develops a lock-on angle. The GSNWK seeker also includes housing and a block of electronics. A system as such is designed, above all, for purposes as follows:
- Automatic detection, tracking, and guidance in many directions (chase, closure, or perpendicular heading in relation to the line of sight) - in UV and IR ranges;
- Automatic angle computation for elevation and intercept;
- Effective discrimination between actual targets and thermal interferences (flares, thermal generators), through UV spectrum detection enhancement;
- Partial kinematic target discrimination;
- Developing intercept signal close to the target, shifting the impact point to the target’s fuselage.
One of the key reasons behind the introduction of the new GSNWK seeker is the necessity to further improve the target/thermal interference discrimination capability. That task is assigned to the seeker’s triple-channel gyroscopic detector block, controlled in a feedback loop by electronics, thus offering a target signal tracking capability.
The radiation is then directed, via the input optics, to two photo-processors operated in different spectral bandwidths. Furthermore, to enhance target-countermeasure-interference discrimination, both signals are separated in time, by a proper displacement within the lens space. The electrical signals devised by the coordinator provide the missile with information on the position of the target, and flares in both bandwidths (angular difference between the gyro-optical axis, and the missile-target line of sight).
The multi-channel nature of the whole system makes it possible to isolate the received target signal which makes the whole seeker indifferent to countermeasures emitting more intense radiation than the target. This design also increases the efficiency of the tracking and designating algorithms, allowing the user to utilize extra seeker operation modes, depending on whether the system is used at night, or during the day. Thermal interferences may be caused by natural sources (radiation reflected from the ground, sunlight), as well as flares deployed by aircraft, or background reflections.
The above means that discrimination between natural and man-made interference is implemented via:
- Spectral filtration via optimization of the GSNWK spectral ranges optimization, with the use of three spectral ranges;
- Spatial-frequency filtering, through modulation of the light beam via analysing photo-detector raster;
- Filtration tailored to the electronic channel;
- Minimized field of view and target intercept;
- Logical target recognition methods.
To accomplish these tasks, numerous innovative solutions have been developed at Telesystem Mesko. For instance, to make optimal use of the signals coming from the detector installed in the spinning lens, the signals are amplified within the lens by lens-mounted preamps. That means the signals do not dissipate in the electrical rotating connector when they are passed into the electronics block.
IR detectors are cooled down to -190°C with the use of seeker-mounted Joule-Thomson condensers, utilizing a compressed gas supply (nitrogen or argon). The detector is cooled only once, and the cooling process happens at the launch site. The working gas is fed into the seeker from a single-use high-pressure tank or the onboard system embedded in the launch platform. During the flight, and the operation of the seeker, the detector temperature is kept at a low level thanks to the liquid gas supply onboard. The amount of the gas available is definitive for the seeker's operation time, and thus - the range of the missile.
IIR Imaging-Tracking Sensor Unit
Another solution prepared by Telesystem-Mesko comes in the form of an IIR imaging seeker. Solutions as such belong to the so-called 4th generation. Multispectral seekers belong to the 3rd generation of such sensors. In the case of the IIR imaging seeker, the target image is created on a sensor made out of numerous detectors arranged into a specific array - previously it was linear (scanned), and now we are dealing with a focal plane array.
The thermal imagery prepared in this way may be compared to images captured by a digital stills camera. The IIR imaging seeker however compares (using a specific algorithm) the pre-loaded model projected onto a 2D plane, with the image projected on the sensor via the seeker's optics. Furthermore, to increase the guidance accuracy in the terminal phase of the engagement, the sensor image is additionally processed with the use of automatic target detection and tracking algorithms.
This solution has not been commonly used in weapons systems before, due to the technological challenges associated with creating small sensor and cooling systems of proper quality, computational power limitations imposed on the onboard computing, and also the high cost. All of the factors listed above are becoming less relevant today, and a broader-scale deployment of IIR seekers will just be a matter of time.
Poland was given a head-start, as it is already manufacturing one of the best MANPADS around the world (“Piorun”). Solutions developed for Piorun may be adopted for a new missile, which would speed up the development and diminish the risk of developing a concept that is entirely fresh and new.
The development works within that scope are pursued in Poland in two areas. The first one envisages the use of a French-made detector for creating an LWIR (12 µm) long-wave seeker based on a bolometric Lynred ATI detector: Advanced Thermal Imager 640 (640 x 480). The research has shown that a solution as such allows one to detect a jet-powered fighter aircraft at a range of at least 10 kilometres.
However, a Polish seeker for the MWIR range (3.7μm – 4.8 μm) is also planned to be developed, based on a cooled T2SL Vigo (640 x 512) detector unit. In this case, a jet-powered fighter aircraft may be detected at a distance exceeding 12 kilometres. In both cases, the mechanical portion of the unit is assumed to be identical. For instance, a two-axis stabilizer unit would be used, with ±30° azimuth and ±30° elevation range, with maximum angular velocity of up to 30 degrees per second in both planes.
This type of seeker may be used in numerous munition types, be it anti-aircraft, anti-tank, or even anti-ship ones. The emergence of such a seeker may redefine the operational side of using such armament, since the munitions are smart, in the sense that they can find a specific enemy asset and hit its weakest point. All of the above would come hand-in-hand with high resistance to active countermeasures and concealing systems.