RWR and Missile Signal Strength on SU-27 question

[Redacuragsr]

When a ER is fired from a SU-27 at another SU-27, does the RWR on the flanker show the strength of the enemy aircraft radar that is tracking you (the flanker radar) or is it showing you the strength of the missile radar that is tracking you. The reason that I am asking is because R-27ER is a semi active missile and doesn’t have a radar of its own, and only really follows the reflection of the radar that is supporting it, unlike the AMRAM which does have its own radar so when it goes active your RWR shows you the strength of missile by which you can gage the distance of the missile from you so that you can have an idea how much time you have to defeat it. It seems to me (and I could be wrong) when I fly the flanker and receive a launch warning that I know is coming from another Flanker (because it’s my buddy firing at me in MP) that the RWR launch warning is showing me the strength of missile (R-27ER) because the illumination strength changes when the RWR goes from lock warning to launch warning. What I don’t understand is how can it show me the radar strength of the incoming missile if the R-27ER is a semi active missile and doesn’t have its own radar, it makes sense with the AMRAM as it only gives you a launch warning when the missile goes active (assuming its being fired in TWS). In the case of the flanker, how does the RWR know the difference between when you are being locked, and when the missile is launched? Does the frequency or strength of the radar beam change in the launching aircraft radar when the missile is being supported? And how does the RWR know the strength/distance of incoming semi active missile if the missile itself is not illuminating you? Does it use the aircraft's own radar strength to estimate the distance of the missile?

 

I am really curious to know what you guys think on this subject, is it a bug, or perhaps it is just simplified or under modeled in DCS, or am I just missing something in my understanding of missile mechanics in DCS. Any feedback is appreciated.

 

Thanks a lot

Edited November 17, 2015 by Redacuragsr

[DarkFire]

I'm not an expert in aircraft radar, but I would imagine that the observed signal strength increases at missile launch because the enemy radar changes from tracking mode to continuous-wave narrow-beam illumination for missile guidance.

 

One of the advantages of the SPO-15 compared to western RWR units is that it does display signal strength. Thus if you can guess the likely identity of the illuminating radar it enables you to calculate the range to the illuminator with surprising accuracy.

[Santi871]

It shows the strength of the missile so basically how close it is, regardless of whether its ARH or SARH. I don't know why this works with SARH or if it's realistic, but that's how it is ingame.

 

Generally RWRs detect launches because guidance PRFs are different, or sometimes continuous wave is used. I believe newer RWRs might also detect datalinks between the missile and the launching aircraft but I'm not sure.

[Redacuragsr]

Hey Darkfire,

 

Thank you for the feedback. So what you are saying is that the RWR on the flanker guesstimates the missile strength/distance based on reading the radar energy from the aircraft itself, right? That's what I was thinking too, but is it also possible that in this case in real life you would just get a launch warning without there being an actual signal strength displayed for the missile, and the strength signal is just a feature of DCS? It's been driving me crazy all day how it figures out the signal strength of the semi active missile itself.

[Redacuragsr]

Hey Santi,

 

The datalink is the only thing that makes sense to me in terms of tracking missile signal strength, but not sure if that is the case with our Flanker variant. Thanks for that clue thought, it's been driving me crazy....:)

[Santi871]

Hey Darkfire,

 

Thank you for the feedback. So what you are saying is that the RWR on the flanker guesstimates the missile strength/distance based on reading the radar energy from the aircraft itself, right? That's what I was thinking too, but is it also possible that in this case in real life you would just get a launch warning without there being an actual signal strength displayed for the missile, and the strength signal is just a feature of DCS? It's been driving me crazy all day how it figures out the signal strength of the semi active missile itself.

 

I have no idea. If I were to speculate, maybe the launching aircrafts radar changes PRF in accordance to the missile's distance to the target to optimize the tracking, I don't think the ER uses continuous wave tracking but the aim7 does I'm pretty sure and the spo15 can still detect its strength. But then again it's speculation.

[Redacuragsr]

I have no idea. If I were to speculate, maybe the launching aircrafts radar changes PRF in accordance to the missile's distance to the target to optimize the tracking, I don't think the ER uses continuous wave tracking but the aim7 does I'm pretty sure and the spo15 can still detect its strength. But then again it's speculation.

 

Yea aim7 is also semi active so I would think it would be tracked in the same way too. Thought I am curious what do you guys think, is this how it works in real life, or do you think this is a game feature made so that we could track and defeat missiles easier?

[Ironhand]

...What I don’t understand is how can it show me the radar strength of the incoming missile if the R-27ER is a semi active missile and doesn’t have its own radar, it makes sense with the AMRAM as it only gives you a launch warning when the missile goes active (assuming its being fired in TWS). In the case of the flanker, how does the RWR know the difference between when you are being locked, and when the missile is launched? Does the frequency or strength of the radar beam change in the launching aircraft radar when the missile is being supported? And how does the RWR know the strength/distance of incoming semi active missile if the missile itself is not illuminating you? Does it use the aircraft's own radar strength to estimate the distance of the missile?

...

I think you are misinterpreting what you're seeing. The only reason for an increase in signal strength on the Berioza is the closing distance between the target (you) and the launching platform (your friend's Su-27). I've never noticed a jump in signal strength caused by the switch from lock to launch. Nor have I seen an increase in signal strength that had anything to do with the closing distance between myself and an R-27ER or R-27; only the closing range between myself and the launch platform.

 

I'm am currently flying Beta 1.5 and, to be sure nothing had gone awry, I just double checked. Everything remains as it has been. The Berioza in the scenario you detailed, is displaying the closing range between you and the launching Su-27.

[Boberro]

SARH missiles won't show on Beryoza.

You will see only launch platform strenght (enemy plane).

 

It works for active missiles though.

[Redacuragsr]

Thank you for clearing that up for me. I am also running 1.5, and thought that it was strange that it jumped, I'll have to take another look at it, may be I missed something. Just wanted to see if anyone else was seeing that.

[Ironhand]

Thank you for clearing that up for me. I am also running 1.5, and thought that it was strange that it jumped, I'll have to take another look at it, may be I missed something. Just wanted to see if anyone else was seeing that.

If you want, you can conduct an experiment. Have your friend in a tail chase situation at the same airspeed as you and just outside of launch range for an R-27RE. Have him lock you and launch an R-27RE while still out of launch range with launch override. Watch your Berioza. Assuming the two of you are traveling at the same airspeed (and same altitude so that both IASs will be the same), the signal strength should neither increase nor decrease.

 

As you already know, and others have mentioned, you'll see something completely different on the Beriosa with an AHR missile like the AIM-120. :)

[apocom]

If you want, you can conduct an experiment. Have your friend in a tail chase situation at the same airspeed as you and just outside of launch range for an R-27RE. Have him lock you and launch an R-27RE while still out of launch range with launch override. Watch your Berioza. Assuming the two of you are traveling at the same airspeed (and same altitude so that both IASs will be the same), the signal strength should neither increase nor decrease.

 

As you already know, and others have mentioned, you'll see something completely different on the Beriosa with an AHR missile like the AIM-120. :)

 

You cannot radarlock onto someone with the same airspeed.

 

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[GGTharos]

If you're shooting AIM-7F maybe. Everything after that is HPRF, in fact the CW illumination switch was removed from the cockpit of the F-15.

 

but the aim7 does I'm pretty sure and the spo15 can still detect its strength. But then again it's speculation.

[Frostie]

If you want, you can conduct an experiment. Have your friend in a tail chase situation at the same airspeed as you and just outside of launch range for an R-27RE. Have him lock you and launch an R-27RE while still out of launch range with launch override. Watch your Berioza. Assuming the two of you are traveling at the same airspeed (and same altitude so that both IASs will be the same), the signal strength should neither increase nor decrease.

 

As you already know, and others have mentioned, you'll see something completely different on the Beriosa with an AHR missile like the AIM-120. :)

You'd probably have to be at full strength to get an impact.

 

The simple test is to get in an F-15 and notice that the 29 spike doesn't get close enough before you are hit. Or say 'it just does'.

 

DCS today you'd need to set up opposing each other at 15000m and launch from 60km to see an impact before full strength was achieved, and that will run close. Long gone are the days of 100km launches.

 

SARH missiles don't show up on the RWR is all the proof I have.

[DarkFire]

SARH missiles themselves cannot show up on EWR equuipment like the SPO-15 because they emit no radar energy, all they do is home in on a reflection from the target that's being illuminated by the launch aircraft. The observed effect is almost certainly due to the launch radar going from PRF search / lock mode to continuous-wave narrow beam target illumination, since in this example the launch aircraft was an Su-27. It may well be the case that this sudden jump in observed emitter magnitude is one of the methods by which the SPO-15 recognises the difference between being locked up and a missile actually being launched.

 

Everything I've read about active MAWS (missile approach warning systems) tells me that they tend to be based on a combination of passive IR or in some cases UV sensors looking for the energy emitted by a missile exhaust and active laser sensors that measure the distance and direction to an approaching missile.

 

For active missile threats, I would imagine that the SPO-15 may or may not be capable of recognising the high PRF mode used by radars such as the APG-63 at the point of missile launch in order to guess that a missile has been launched, and will of course detect the direct illumination by the missile radar at the point at which the missile goes active. At that point the SPO-15 will report the observed signal strength from the missile radar.

[Santi871]

If you're shooting AIM-7F maybe. Everything after that is HPRF, in fact the CW illumination switch was removed from the cockpit of the F-15.

 

Oh, I guess it's only flood mode that uses CW?

 

Either way, interesting stuff in this thread, I'll test all this stuff out later.

[GGTharos]

AFAIK it uses HRPF. Specifically, it uses the same emission as STT per -34 to guide the modern sparrow. Back in the day when the radar had a CW mode, maybe FLOOD did also.

 

Oh, I guess it's only flood mode that uses CW?

 

Either way, interesting stuff in this thread, I'll test all this stuff out later.

[Ironhand]

You cannot radarlock onto someone with the same airspeed.

 

Yup. That's what I get for making a suggestion before I've finished my first cup of morning coffee. The fog hasn't completely left my brain yet.

 

So, according to that, we can close the gate completely, if we want. Didn't know where it was.