Lock / Launch / RWR

[asparagin]

I haven't been able to find a good explanation on how come does the RWR detects missile launches (Let's stick to SARH's). The difference between "search" and "lock" is clear. The latter will send more energy (more impulses / time). But when a SARH missile is launched, the enemy radar stays in lock mode. What changes, so that a launch is signaled and why?

[Nate--IRL--]

I'd imagine the radar emissions change from being a simple target lock, to a target lock + a higher power radar illumination of the target for the missile to track.

 

Nate

[Insanatrix]

Well according to Wikipedia, it states:

 

"The RWR can be an important tool for evading threats if avoidance has failed. For example, if a SAM system or enemy fighter aircraft has fired a missile (for example, a SARH-guided missile) at the aircraft, the RWR may be able to detect the change in mode that the radar must use to guide the missile and notify the pilot with much more insistent warning tones and flashing, bracketed symbols on the RWR display."

 

I'm sure someone with more technical background can explain it in greater detail.

[asparagin]

But if it is like this: guidance: more pulses than lock, what's the logic? Why not always paint with "guidance pulses" - instead of lock, like this the enemy won't know when I launch.

On the other hand, how come there is no "taunt signal": radar signal that simulates a launch, it could be very useful I can imagine.

[Nate--IRL--]

Higher radar power emissions broadcasts your position a lot further, this would be kept to a minimum ideally and only used when needed (ie missile launch). As far as taunt signals go ECM and ECCM gets very complicated. I'd imagine a lot of computer power is used to filter out bluffs and counter bluffs, but I'm just guessing.

 

Nate

[asparagin]

Higher radar power emissions broadcasts your position a lot further, this would be kept to a minimum ideally and only used when needed (ie missile launch).

 

As I'm sure you know, the timeframe which is relevant before/during a launch is a matter of seconds / minutes. So I don't need to broadcast all the time guiding signals, just enough that the enemy doesn't know exactly when I fire.

[Insanatrix]

SARH missiles require tracking radar to acquire the target, and a more narrowly focused illuminator radar to "light up" the target in order for the missile to lock on to the Radar return reflected off target.

 

They use continuous wave radar for guiding the missile and pulse doppler for tracking. When you fire the missile the continuous wave guidance kicks in basicly which is what triggers your RWR that a missile has been launched.

[asparagin]

SARH missiles require tracking radar to acquire the target, and a more narrowly focused illuminator radar to "light up" the target in order for the missile to lock on to the Radar return reflected off target.

 

They use continuous wave radar for guiding the missile and pulse doppler for tracking. When you fire the missile the continuous wave guidance kicks in basicly which is what triggers your RWR that a missile has been launched.

 

Yes, this can basically be summed up as "more energy".

[Insanatrix]

Well it wouldn't be practical in any event to focus your entire radar on 1 target unless it was to guide a missile. You are potentially blinding yourself to any other threats that may exist. He will just go defensive and his wingman will nail you.

[asparagin]

Well it wouldn't be practical in any event to focus your entire radar on 1 target unless it was to guide a missile. You are potentially blinding yourself to any other threats that may exist. He will just go defensive and his wingman will nail you.

 

see post #6

[GGTharos]

Good question, and the real answer is that it is not easy to answer.

 

In the past, radars would switch waveform (usually just PRF, but maybe more characteristics too) when transitioning from track to illumination mode which could trigger the missile launch warning.

Another possibility is that the missile datalink starting up on the exact same azimuth as the STT signal would trigger it as well, but that's a little iffy.

More modern radars and in particular missiles might not require any wave-form changes at all, so you might get zero indications than anything has been launched.

 

In general, and only AFAIK, STT in RL is considered not only provocation, but reason to start going defensive.

 

I haven't been able to find a good explanation on how come does the RWR detects missile launches (Let's stick to SARH's). The difference between "search" and "lock" is clear. The latter will send more energy (more impulses / time). But when a SARH missile is launched, the enemy radar stays in lock mode. What changes, so that a launch is signaled and why?

[asparagin]

Another possibility is that the missile datalink starting up on the exact same azimuth as the STT signal would trigger it as well, but that's a little iffy.

 

This sounds also reasonable, with the condition that the nature of communication (more or less radar bandwidth) between launching platform and missile allows it.

 

More modern radars and in particular missiles might not require any wave-form changes at all, so you might get zero indications than anything has been launched.

 

In general, and only AFAIK, STT in RL is considered not only provocation, but reason to start going defensive.

 

Yes, I guess it's more of a gray area, then "search", "lock" and "launch".

[Insanatrix]

TBH im still a tad lost. You want to fake a missile launch?

[asparagin]

It's just about the understanding of how it works, exploiting comes instinctive :D

[GGTharos]

So far, at least AFAIK such exploiting has been impractical.

 

It's just about the understanding of how it works, exploiting comes instinctive :D

[Exorcet]

But if it is like this: guidance: more pulses than lock, what's the logic? Why not always paint with "guidance pulses" - instead of lock, like this the enemy won't know when I launch.

On the other hand, how come there is no "taunt signal": radar signal that simulates a launch, it could be very useful I can imagine.

 

 

This is a guess, but it could have to do with enemy SA. It's not just going to be fighter vs fighter, but fighter + AWACS + ground radar + stand off jammers + etc vs the same (maybe).

 

If your radar is jammed, you can't lock on to taunt. If your range is suspiciously high (as reported by AWACS or your target's own radar) when you give a firing signal there is a good chance that it is a bluff, plus with a SARH missile you can only bluff one enemy at a time, leaving his allies free to cover him. They could all be sharing information over radio or via datalink, collectively monitoring enemy radar activity to figure out what is fake and what isn't.

[asparagin]

This is a guess, but it could have to do with enemy SA. It's not just going to be fighter vs fighter, but fighter + AWACS + ground radar + stand off jammers + etc vs the same (maybe).

 

Of course under this condition, with or without taunting, you would be lost.

[RIPTIDE]

Good question, and the real answer is that it is not easy to answer.

 

In the past, radars would switch waveform (usually just PRF, but maybe more characteristics too) when transitioning from track to illumination mode which could trigger the missile launch warning.

Another possibility is that the missile datalink starting up on the exact same azimuth as the STT signal would trigger it as well, but that's a little iffy.

More modern radars and in particular missiles might not require any wave-form changes at all, so you might get zero indications than anything has been launched.

 

In general, and only AFAIK, STT in RL is considered not only provocation, but reason to start going defensive.

AFAIK in real life when a missile fires the launch craft radar goes from Pulse mode to Continuous Wave mode. Easily recognisable by a RWR. This is of course STT. Obviously in a TWS type mode, in a strong radar, the tracking Pulse mode is strong enough to guide a missile to pitbull. I expect FLOOD mode in a F-15 is a CW transmission within larger cone than a STT. But at short ranges the power is so strong within that cone that it is sufficient to provide for the lock.

[GGTharos]

Going to CW is preeeeeetty old, and IIRC not needed with monopulse seekers.

[RIPTIDE]

Going to CW is preeeeeetty old, and IIRC not needed with monopulse seekers.

Ya I agree.

[macrylinda]

As I'm sure you know, the timeframe which is relevant before/during a launch is a matter of seconds / minutes. So I don't need to broadcast all the time guiding signals, just enough that the enemy doesn't know exactly when I fire.

SARH missiles require tracking radar to acquire the target, and a more narrowly focused illuminator radar to "light up" the target in order for the missile to lock on to the Radar return reflected off target.

 

They use continuous wave radar for guiding the missile and pulse doppler for tracking. When you fire the missile the continuous wave guidance kicks in basicly which is what triggers your RWR that a missile has been launched.

[nomdeplume]

They use continuous wave radar for guiding the missile and pulse doppler for tracking. When you fire the missile the continuous wave guidance kicks in basicly which is what triggers your RWR that a missile has been launched.

 

The two posts just before you suggest this hasn't been the case for a long time. But I would think that the missile (with its relatively limited receiver) would need a very strong signal in order to be able to reliably pick out its target from everything else (since everything else in the sky is also going to be illuminated by several different radars).

 

So, the increased signal strength and tighter focus is probably enough to be able to provide a strong warning that the missile was launched.

 

But then - why not 'fake it'? I don't know, but here's some conjecture.

 

For air-to-air:

 

If you're outside your max range, your target is going to know it because their RWR will tell them. So faking a launch outside your maximum range serves no purpose.

 

If you're within range, the typical response to a missile launch is for your target to immediately launch a missile at you and then go defensive (i.e. putting you on gimbals). At this point, you've handed them the tactical advantage because they only think they have a missile inbound, while you actually do have a missile (or two) inbound. You've given up first-shot advantage, and for what? All you can do now is fire your own missiles and go defensive yourself, but there's already have a head start and will reach you first.

 

So I think it would rarely be practical in air-to-air combat. And for intimidation purposes (e.g. enforcing a no-fly zone) STT mode would be sufficient.

 

For surface-to-air:

 

Again, if they're outside your range they'll know it and will disregard your attempts to frighten them.

 

If they are within your range, what purpose does faking a launch serve? If they're at a reasonable distance they won't take immediate action anyway, since they can take their time to evade. And by then they'll grow suspicious at the lack of a smoke plume.

 

If they're close enough that they would take immediate evasive action even without a visual sighting, then why on earth wouldn't you fire an actual missile? You're a SAM site, you've got tonnes of them! And every enemy aircraft is a potential threat to you and/or the things you're supposed to be protecting.

 

There might be some value in faking launches in order to lull them into a false sense of security, "boy who cried wolf"-style. However it's unlikely that any aircraft would hang out in your engagement zone for long enough to start ignoring missile launch warnings, unless perhaps those aircraft are on a SEAD mission, in which case taunting them with high-strength radar seems a suboptimal survival strategy.

 

I do remember receiving false launch warnings from SAM sites in F4AF, though. They did tend to put me a bit on edge, but a quick visual check confirmed there was no actual launch - so I think the psychological effect against trained and disciplined pilots would be marginal at best.