What you state above are not false but not totally correct. Your information needs to be updated. I am talking about Hisar family which is carrying the latest technology inside but what you tell is the learning from old generation IR/IIR guidance methods. You will get the corrected response of your claims step by step!
Infrared seekers are passive devices, which unlike Rf seekers, provide no indication that they are tracking a target. This makes them suitable for sneak attacks during visual encounters, or over longer ranges when used with a forward looking infrared system. This makes heat-seekers extremely deadly. They are subject to a number of simple countermeasures, most notably dropping flares behind the target to provide false heat sources. This only works if the pilot is aware of the missile and deploys the countermeasures, and modern seekers (to be explained below) have rendered these increasingly ineffective even in that case.
- Contrary to general consideration, New IIR seekers successfully lock onto any sections of aircraft that spreads lower level signals than exhaust thanks to advanced frequency sensitivity of last generation detectors in modern IIR missiles
New seekers which is sensitive to both the exhaust as well as the longer 8 to 13 micrometer wavelength range, which is less absorbed by the atmosphere and allows to lock onto the lower level signals coming from the front and sides of an aircraft fuselage. Modern seekers combine several detectors and are called two-color systems which enables them to track not only exhausts but also any section of aircraft spreading lower level thermal signals.
- Effectiveness of IIR seekers to lock onto target while target itself is trying to fool seekers to avoid to be targeted. (Sun and Flares)
Advanced detectors come with advanced image processors on those missiles. Modern heat-seeking missiles use imaging infrared(IIR), which is able to produce an image in infra-red, much like the CCD in a digital camera. This requires much more signal processing to be much more accurate and harder to fool.
Advanced detectors tracking the targets in different wavelengths along with advanced image processors make them incredible deadly and so, old tricks to fool seeker with Sun became unlikely because image processors identify the target shape, even capability of locking onto the section which spreads lower level thermal signals than exhaust. Auto dimmer is also used by those processors.
Resistance to Flares (Main tool to defeat IIR seeker), Early seekers used a single detector that was sensitive to very hot portions of the aircraft like jet exhaust, making them suitable for tail-chase scenarios but This caused them to be fooled by flares easily. New seekers have a dual-frequency seeker which is able to distinguish flares from the actual target.
Other solution to overcome flares are digital processing. In this method, The target data taken by seeker detectors processed to produce an image, something like desktop scanner. Image Processors remember the location of the target from scan to scan, objects moving at high speeds relative to the target could be eliminated. That is called as cinematic filtering !
- Most modern IIR Missiles' lead collision interception method
The original and older generation IR missiles would simply point towards the target with narrow looking seekers and chase it not to make them exit out of FOV like you told but this was inefficient in many aspect and absorbing the acceleration energy and thrust power of missiles.
Newer IIR missiles are smarter and use the gimbaled seeker head combined with
"proportional guidance" in order to avoid oscillation and to fly an efficient intercept path. Proportional guidance is a method widely used by captains/officers working in merchant ships to avoid collision with another ship navigating in a collision route. It is based on the fact that two vehicles are on a collision course, when their direct line of sight does not change direction but the range closes steadily.
How it works in missiles ? Gimbal seeker turns towards target to lock on, while Missile is proceeding a steady course different than the direction of seeker. A gyroscope inside of seeker continuously calculate the relative bearing (constant bearing) thanks to data taken by gimballed seeker, while the distance between them are decreasing. If the constant bearing chances a bit thanks to escape maneuvering of target, Gimballed seeker will follow the move, while the processor in missile will immediately draw a new route to make bearing angle the constant again until missile and target collide.
As I said, It is the same method used in merchant ships when radars are not used. Officer on watch track the target ship with naked eye/bearing device on compass and wait a few minutes to take second bearing angle. If the sight angle/bearing does not change during passing time, It means The ships are in collision route.
Hisar-A/O gimbal seeker head with proportional navigation capability
- About impact point of IIR missiles and generated solution.
Older generation IR/IIR missiles was capable to just lock on hot sections of targets, making them suitable for tail-chase scenarios so Impact should just be possible with hit to kill principles. Hit to kill principles was mostly applied as effective solution for missiles reaching mid to long altitude air layers cause of thick atmosphere. Old IIR seekers was ineffective against fast moving targets which is capable of escaping from their narrow FOV but New generation IIR missiles have advanced image processor, multi-frequency detectors and gimbaled seekers which make them advanced enough to chase the targets with proportional navigation principles and impact in either colliding with target to activate warhead or impacting in closest point thanks to proximity fuse.
IIR seekers can't calculate the distance true but They actually don't need to do but How their proximity fuse works ? The method are working with side laser to trigger the detonation. While the missile cruises towards its target, the laser energy simply beams out into space. When the missile pass its target some of the energy reflected by the target back to missile and detectors sense it and detonate the warhead.
As you see IIR missiles are way complex and advanced enough to fulfill their missions. What you pointed out as deficiency of IIR missiles are actually updated on newer missiles and their sensors. Their passive tracking performance along with many other sight and processing technologies are the reason They are called as deadly and sneaky missiles which is very very hard to jam/escape once It is launched. The biggest handicap of IIR missiles are
range limitation and weather conditions but The performance of IIR sensors change in accordance with detector type in foggy misty weather conditions.
Let me explain the performance of IIR seekers in different weather conditions.
- Effects of Weather Condition in performance of IIR seekers
Clear skies on relatively high temperature regions such as Central Anatolia are convenient to IIR seeker. Rainy, Foggy, Misty weather conditions such as East Black-Sea effect the detecting range/visibility of seeker robustly at terminal phase.
The best sensor performing better results are LWIR in Category-1 and 2 class fog. IIR seeker head with LWIR detectors can't perform anything better than the performance of a naked eye in Category-3 so
Active RF seeker is better on longer ranges without being effected by wheather conditions but
open more to be jammed/detected by enemy sensors.
Here is the results of detection range (km) performance of different bandwidth (Naked Eye, MWIR, LWIR) IIR seekers in a condition of a 10 degree temperature differences between ground and target location. As It is seen, The naked eye performs better than any sensor in category-III heavy foggy condition, because heavy fog clouds can't be penetrated by thermal radiations . In Category-II, LWIR is 4x superior to MWIR.
Rain can significantly reduce target contrast on IIR sights and LWIR or MWIR perform similarly in the presence of rain. Range on rainy weather is a dramatic drop off in the 100-500 meter range.
Category I: visual range 1220 meters
Category II: visual range 610 meters
Category IIIa: visual range 305 meters
Category IIIc: visual range 92 meters
so Combination of both sensor on a deadly low and medium range national missile system inside of same launchers will make a big surprise to enemy assets supposing to benefit the atmospheric conditions in favor of own interests to reach their targets.
The best IIR solution from Aselsan. Dual-Band
You can not see all you want in Roketsan website. There are dozen of missile programs from MANPADS to Long Altitude SAMs proceeding under the leadership of Roketsan and None of them are included into there. You can check this table to see ongoing SAM programs developed under the collaboration of Roketsan/TübitakSAGE and Aselsan team.
