Missile guidance software

Treachery

New Member
Where is the program that guides the missile onto its target stored in the seeker head? Is it in a RAM/ROM assembly or some sort of small HDD? I mean in missiles with fire and forget capability that don't receive any course correction instructions from their hosts.
 

stigmata

New Member
Long range missiles do recieve mid cource update, if avaliable.
I cant imagine a HDD to withstand that kind of punishment.
 

Chrom

New Member
Where is the program that guides the missile onto its target stored in the seeker head? Is it in a RAM/ROM assembly or some sort of small HDD? I mean in missiles with fire and forget capability that don't receive any course correction instructions from their hosts.
There are all sort of things inside different missiles. RAM, ROM, magnet disks (something a-like HDD but not quite), etc. Depending from missile generation and purpose.

All modern missiles at very least have both ROM and RAM.
 

Treachery

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Thanks, I thought so too. I use to program little experimental hobby robots and I've always wondered that and found it an interesting subject. As Stigmata pointed out I guess most traditional, off-the-shelf HDDs can't withstand the extreme G forces involved but there are now RAM-based solid state drives that feature both non mechanical, random data access and faster transfer rates. These are even available for home PCs, can be bought online from sites like Newegg.com.

Low flying cruise missiles with terrain contour matching capability need some serious data storage to keep all that prerecorded contour data and flight-path/waypoint information, so I guess those definitely come with some sort of large-capacity solid state drive.

Shorter range, tactical missiles like Stinger, Igla, etc., can probably do with only about a single, primitive 128KB RAM chip, as all it needs to store is a little code that says "keep the hottest dot in the center of the field of view". Unfortunately, these can easily be tricked with flares or infrared jammers though. Missile can get smarter with a better seeker and more lines of wisely written code but it also requires more RAM storage and processing power to handle all those instructions in real time.
 

Chrom

New Member
". Unfortunately, these can easily be tricked with flares or infrared jammers though. Missile can get smarter with a better seeker and more lines of wisely written code but it also requires more RAM storage and processing power to handle all those instructions in real time.
Even such simple missiles are not as easy to flare or jam as one might think. They usually follow very specific part of IR and UV spectrum (early 80x technology), being special to engines. It is not easy (if not impossible) to get same spectrum from flares - flares have own signature, and if missile producer know this signature the chances to successfully reject flares are greatly increased. Reverse is also true - if flare producer exactly know rejection algorithm he can develop better flare. This is reason why older missiles are much more suspectible to modern flares.Still, even most modern flares have only average effectiveness against early 80x dual-band seekers like found in the later generation Stingers or Igla-S.
 

Treachery

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Thanks for the reply Chrom. So, I guess newer missiles like AIM-9X feature both a better flight path / countermeasure avoiding algorithm and more sensitive longer range IR/UV seekers that are fine tuned to characteristic heat signatures from various engines.

What I'm wondering is, though, how can an IR/UV seeker continuously track a particular wavelength from the engine when a flare burns between the missile itself and the target it's following and literally "blinds" the missile's IR/UV receptors for some time. If the flare falls on direct line of sight, even very briefly, I think it can effectively block all the heat coming out of the engine and cause the missile to lose signal. Think of it like our inability to see the stars when there's a brighter object (like the sun) on the sky.

Does the missile then ignore the flash and re-acquire the target's engine signature once it's flown past the burning flare?
 

Chrom

New Member
Thanks for the reply Chrom. So, I guess newer missiles like AIM-9X feature both a better flight path / countermeasure avoiding algorithm and more sensitive longer range IR/UV seekers that are fine tuned to characteristic heat signatures from various engines.
Very modern missiles like AIM-9X have matrix image-seekers, either IR or UV or both. Even single-band IR image seekers are generation ahead in terms of jamming resistance to old dual-band non-imaging seekers.

What I'm wondering is, though, how can an IR/UV seeker continuously track a particular wavelength from the engine when a flare burns between the missile itself and the target it's following and literally "blinds" the missile's IR/UV receptors for some time.
It is not easy to blind such sensor. When flare is between seeker and target than it is hard to see target - but missile dont need to. It flying in right direction anyway. The interesting thing happens when flare is slowed and flys away from target. Here various algorithms take place, based on initial, already remembered target spectrum, speed, direction, acceleration, etc..

If the flare falls on direct line of sight, even very briefly, I think it can effectively block all the heat coming out of the engine and cause the missile to lose signal. Think of it like our inability to see the stars when there's a brighter object (like the sun) on the sky.
Yes, might very briefly (for split second) lose signal and then require it. In fact, missile dont completely lose signal, it just becomes hard to differ flare. Once flare flys away from target - than missile should choose between 2 signals. This is when spectrum and algorithms kick in.
Does the missile then ignore the flash and re-acquire the target's engine signature once it's flown past the burning flare?
Missile will try to reject flare instantly, once it is far enough from target to differentiate 2 different signal sources.
 

gf0012-aust

Grumpy Old Man
Staff member
Verified Defense Pro
Does the missile then ignore the flash and re-acquire the target's engine signature once it's flown past the burning flare?

depends on the seeker management system - but modern seekers will actually do a probable intercept if the signal is disrupted. it's designed to "fly through".
 

Treachery

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but modern seekers will actually do a probable intercept if the signal is disrupted. it's designed to "fly through
What if the missile physically hits/touches the flare? Is the warhead than triggerred or does it depend on the kind of fuse used? And when exactly does the missile decide to arm its warhead?
 

Chrom

New Member
What if the missile physically hits/touches the flare? Is the warhead than triggerred or does it depend on the kind of fuse used? And when exactly does the missile decide to arm its warhead?
1. The probability is extremely low, and flare is also quite small.

2. Many (if not most) missiles have just proximity fuses anyway.

3. However small flare is, it still can damage fragile missile if directly hit.

4. I dont really know when warhead is armed... it its probably different for different missiles.
 
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