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Switching to MPRF after target lock


Ironhand

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Honoring Breakshot's request that this topic not derail the "AIM-120 and R-27 homing" thread in which he is involved, I'm starting this as a new topic.

 

There has been a bit of discussion concerning the Su-27's Radar Aiming Complex and whether or not switching to Rear Aspect PRF (MPRF) after target lock within 25 km improves the chances of maintaining lock through the notch. Several people swear by it. Others question it. I've seen no good data in support and most of what I've seen is anecdotal.

 

So I decided to test it for myself again but, this time, with better controls. I have seen the procedure described as "inside 25 km, switch to Rear Aspect PRF after STT lock and the lock will be maintained through the notch". I have also seen the switch described as needing to be done "prior to STT lock".

 

Regardless of when it's done there is absolutely no difference in what happens. I haven't tested this to death because, as Breakshot insists, there's no need to. R-27ER shots are not missing because the Radar Aiming Complex was in the wrong PRF either before or after launch. They are missing primarily because of chaff or other factors that come into play.

 

Attached is my test TRK. The situation is look-down. I'm at 6K meters, the target at 3K. The F-15 has no countermeasures to expend. So this is purely a maneuvering/aspect test. I enter the cockpit, switch on Baro Hold, acquire the F-15 in Front Aspect PRF (HPRF), and launch the R-27ER at the 20 km mark without switching to Rear Aspect. As the -15 maneuvers into the notch, the Aiming Complex goes into MEM Mode (flashes 3 times) and, then, relocks jumping to the -15's new heading and the missile hits shortly after.

 

If you decide to test this yourself, take control of the aircraft just prior to the missile launch and switch to Rear Aspect, you will see precisely the same Radar Complex behavior. If you are testing this, there is no need--and you should not--fly the aircraft. Just manage the PRF setting and launch at the 20km range mark.

 

FWIW, I also tried this making the PRF switch prior to STT lock. Precisely the same behavior from the Complex as well.

 

Darkfire, I've been slowly slogging through the real world manual available online and, so far, I've seen no references to switching PRF settings after launch.


Edited by Ironhand

YouTube Channel: https://www.youtube.com/channel/UCU1...CR6IZ7crfdZxDg

 

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I've posted two tracks in a zip file for you to look over.

 

1st track

Hi PRF stay Hi PRF

 

locking up a low head on contact at about 25km in Hi PRF

the contact turns away enters the notch and turns cold

the system loses lock at the notch so switches to EOS lock

the contact is fully cold now but only EOS lock remains

R-27ER fired on cold target dead off the rail

 

2nd track

Hi PRF switch Med PRF

 

locking up a low head on contact at about 25km in Hi PRF

immediately switching to Med PRF

the contact turns away enters the notch and turns cold

the system loses lock at the notch so switches to EOS lock

the contact is fully cold now but the system reacquires radar lock and also maintains EOS lock

R-27ER fired on cold target and immediately starts tracking

 

 

By switching PRF during lock not only does it help keep a radar lock on the contact but also if you lose track totally eg. the contact is slow low heat source then you immediately are at Med PRF at the drop to continue scanning in the optimal PRF setting.

 

It has been like this since LOMAC. The AI is not a very good practice partner, they are predictable and don't try and hide from you. Multiplayer has so much variation in the opponents you face trying new tactics out works in mp because of this and the lack of an all knowing AI. There are so many tricks you can pick up in mp that you just couldn't do against the AI.

PRF test.rar


Edited by Frostie

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I've posted two tracks in a zip file for you to look over.

 

1st track

Hi PRF stay Hi PRF

 

locking up a low head on contact at about 25km in Hi PRF

the contact turns away enters the notch and turns cold

the system loses lock at the notch so switches to EOS lock

the contact is fully cold now but only EOS lock remains

R-27ER fired on cold target dead off the rail

 

2nd track

Hi PRF switch Med PRF

 

locking up a low head on contact at about 25km in Hi PRF

immediately switching to Med PRF

the contact turns away enters the notch and turns cold

the system loses lock at the notch so switches to EOS lock

the contact is fully cold now but the system reacquires radar lock and also maintains EOS lock

R-27ER fired on cold target and immediately starts tracking

 

 

By switching PRF during lock not only does it help keep a radar lock on the contact but also if you lose track totally eg. the contact is slow low heat source then you immediately are at Med PRF at the drop to continue scanning in the optimal PRF setting.

 

It has been like this since LOMAC. The AI is not a very good practice partner, they are predictable and don't try and hide from you. Multiplayer has so much variation in the opponents you face trying new tactics out works in mp because of this and the lack of an all knowing AI. There are so many tricks you can pick up in mp that you just couldn't do against the AI.

Thanks. I'll check them once I get home from work this afternoon. Hopefully these aren't multiplayer tracks but I fear they are.

 

The AI might not be as skilled but they are great for testing things like this simply because they are predictable. The controls are easier to establish. In the multiplayer environment it's virtually impossible to establish the proper testing control points. The trickiness of humans has nothing to do with the equation. Creating exactly the same situation during the testing trials does.


Edited by Ironhand

YouTube Channel: https://www.youtube.com/channel/UCU1...CR6IZ7crfdZxDg

 

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I've posted two tracks in a zip file for you to look over.

 

1st track

Hi PRF stay Hi PRF

 

locking up a low head on contact at about 25km in Hi PRF

the contact turns away enters the notch and turns cold

the system loses lock at the notch so switches to EOS lock

the contact is fully cold now but only EOS lock remains

R-27ER fired on cold target dead off the rail

 

2nd track

Hi PRF switch Med PRF

 

locking up a low head on contact at about 25km in Hi PRF

immediately switching to Med PRF

the contact turns away enters the notch and turns cold

the system loses lock at the notch so switches to EOS lock

the contact is fully cold now but the system reacquires radar lock and also maintains EOS lock

R-27ER fired on cold target and immediately starts tracking

 

 

By switching PRF during lock not only does it help keep a radar lock on the contact but also if you lose track totally eg. the contact is slow low heat source then you immediately are at Med PRF at the drop to continue scanning in the optimal PRF setting.

 

It has been like this since LOMAC. The AI is not a very good practice partner, they are predictable and don't try and hide from you. Multiplayer has so much variation in the opponents you face trying new tactics out works in mp because of this and the lack of an all knowing AI. There are so many tricks you can pick up in mp that you just couldn't do against the AI.

 

Frostie, have you tried instead of switching to MED straight away after lock, to keep Hi mode and only switch to ILV once target enters the beam and only switch to MED once target starts turning cold?

When I try this without messing up PRF order in my head, Im usualy able to keep the radar and ER tracking throughout.

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Frostie, have you tried instead of switching to MED straight away after lock, to keep Hi mode and only switch to ILV once target enters the beam and only switch to MED once target starts turning cold?

When I try this without messing up PRF order in my head, Im usualy able to keep the radar and ER tracking throughout.

 

I put this up for a night and day example. I usually go straight to ILV after 40km and like you say select Medium when he is going cold.

"[51☭] FROSTIE" #55

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VERY interesting. It's not that the PRF mode keeps the lock from breaking in the first place, when a target enters the notch. But it does effect the reacquisition on the back side of the broken radar lock, once the target exits the notch.

 

I've attached a TRK. It's your original "Hi PRF stay Hi PRF.trk" that I take control of partway through.

 

 

  1. When you see the launch override cue, I've taken control.
  2. Missile 1 is launched HPRF with ТП dislayed.
  3. On the shift to MPRF, ТПРЛ appears and 2nd missile is launched.
  4. Shift to ILV is made just prior to missile 3 (ТПРЛ indication remains).
  5. Shift to HPRF (indicator switches to ТП only) and missile 4 is launched.
  6. Mid flight, shift to MPRF. Radar reacquires and locks target and missile changes to an intercept course.

 

I also took control of your 2nd track where you shift to MPRF. In that track I moved back into HPRF and there was no difference between your track and my result. In that track the PRF setting made no difference.

 

So I stand corrected. For the most part, there is a benefit to switching to either ILV or MPRF once the range closes as the radar is then more likely to re-lock the target after it exits the notch. It doesn't seem to effect whether or not the lock is broken at the notch. But it does have an effect after the target exits the notch.

Hi PRF sequencing PRF modes-Ironhand.trk

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Thanks Frostman! I'm sure with the right timing, STT can be sustained throughout especially in look up. ILV is more reliable than high PRF stability wise and must be used in the transition between head on and beam aspect.

 

At any rate, evidence has now been provided showing that switching PRF mid-flight can help the missile come back from the dead.

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So I stand corrected. For the most part, there is a benefit to switching to either ILV or MPRF once the range closes as the radar is then more likely to re-lock the target after it exits the notch. It doesn't seem to effect whether or not the lock is broken at the notch. But it does have an effect after the target exits the notch.

 

It's not that is more likely, it will reacquire a lock when the contact comes out of the notch, cold, provided the contact is within the PRF acquisition range and EOS has maintained track. Obviously MPRF has the best range against cold contacts while HPRF the worst. As you found out HPRF does work but clearly this is not the optimal choice.

 

But that is not just the only benefit of switching during lock. To maintain track in the notch the target must be giving off enough heat for the EOS to keep track. If not the track will be lost and you go back to search mode. By switching PRF during the lock it will also give you the benefit of being at Med or ILV when back to search mode happens.

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In my experience ILV mode is useless all around... MED maintains lock much better in all aspects providing the target is within 25km range, which is when it usually counts for guiding that ER shot (if it doesn't just go for chaff like a dud... sigh). Also note the significant difference in refresh rates between ILV and the dedicated aspect PRFs. ILV is so agonizingly slow...

 

So keeping it simple, best SOP would be, lock target, switch to MED within 25km. There are other tricks with radar for maximizing scan patterns, etc, but I think I'd rather keep that internally for squad use. ;)


Edited by Breakshot

 

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The lock is dropped precisely because you skip ILV by switching from HPRF to MPRF straight away. In STT refresh rate is less of a concern since the radar emitts at max power. ILV is more versatile than MED aspect wise.

 

And you can still beat the notch and maintain the lock at all times by flying lower than the target. Dropping the lock is not a must and will happen only if you select MED out of its range or let the target go below your altitude.

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The lock is dropped precisely because you skip ILV by switching from HPRF to MPRF straight away. In STT refresh rate is less of a concern since the radar emitts at max power. ILV is more versatile than MED aspect wise.

 

And you can still beat the notch and maintain the lock at all times by flying lower than the target. Dropping the lock is not a must and will happen only if you select MED out of its range or let the target go below your altitude.

Here's the thing... it's not! As much as it should be in theory... In DCS, MPRF works perfectly in all aspects under 30km. You can scan, track, and STT perfectly within those parameters. It's faster all around and more 'bulletproof'.

 

Should the bandit get into the notch correctly, the lock will switch to EO regardless of PRF anyway, but your best chance of reaqcuiring is with MED. ILV has abysmal rear hemisphere performance of something like 15km at best (which defeats the point of using it), not to mention about the super slow refresh rate when scanning.

 

In any case, I haven't lost any locks I shouldn't have under those circumstances yet so, not sure where you got that from...

 

You are right about STT not affected by refresh rate however.

 

As for being below the bandit, it is a must for guiding a SARH missile obviously. However you would be surprised with wacky DCS notch modeling since FC2. There are times where you can be 'notched' in a look up situation. It defeats all logic, but happens, speed is the factor here.

 

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Edited by Breakshot

 

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...Dropping the lock is not a must and will happen only if you select MED out of its range...

Really? Perhaps I'm misunderstanding but, so far, I haven't seen anything to indicate that changing the PRF setting is actually changing the STT PRF. Or am I missing something. The only difference I see is on the back end. After the lock is dropped, being in either MPRF or ILV makes it easier for the radar to reacquire and relock. The same thing happens by waiting to change PRF until the lock is dropped. Though, in that case, reacquiring may take a fraction of a second more.

 

It's not that is more likely, it will reacquire a lock when the contact comes out of the notch, cold, provided the contact is within the PRF acquisition range and EOS has maintained track. Obviously MPRF has the best range against cold contacts while HPRF the worst. As you found out HPRF does work but clearly this is not the optimal choice.

 

But that is not just the only benefit of switching during lock. To maintain track in the notch the target must be giving off enough heat for the EOS to keep track. If not the track will be lost and you go back to search mode. By switching PRF during the lock it will also give you the benefit of being at Med or ILV when back to search mode happens.

I agree whole heartedly. I said "more likely" for the reasons you stated.


Edited by Ironhand

YouTube Channel: https://www.youtube.com/channel/UCU1...CR6IZ7crfdZxDg

 

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Ironhand, the PRF does change during STT, you can test it by switching to MED at beyond its range, say at 60km. You should lose STT lock...

 

MED will always work better in off-angle conditions with a maneuvering target, providing the range is within 30km. The difference is small but when the SARH are so terrible to start with, every little % counts.

 

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Here's the thing... it's not! As much as it should be in theory... In DCS, MPRF works perfectly in all aspects under 30km. You can scan, track, and STT perfectly within those parameters. It's faster all around and more 'bulletproof'.

 

Should the bandit get into the notch correctly, the lock will switch to EO regardless of PRF anyway, but your best chance of reaqcuiring is with MED. ILV has abysmal rear hemisphere performance of something like 15km at best (which defeats the point of using it), not to mention about the super slow refresh rate when scanning.

 

In any case, I haven't lost any locks I shouldn't have under those circumstances yet so, not sure where you got that from...

 

You are right about STT not affected by refresh rate however.

 

As for being below the bandit, it is a must for guiding a SARH missile obviously. However you would be surprised with wacky DCS notch modeling since FC2. There are times where you can be 'notched' in a look up situation. It defeats all logic, but happens, speed is the factor here.

 

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MED wont help you outside 30km in STT. Unless you want to drop the lock (why would you), ILV is a better transition until target gets close enough/turns cold.

 

Of course lock will drop regardless of PRF if you allow the notch to happen, the idea here is to keep a steady lock as much as possible.

 

Anyway, my initial aim was to make people aware that post-launch PRF tweaking does exist for in-game N001 and that if correctly handled does help with tracking and guiding SARH.

 

CM interaction maybe needs revisiting but one must make sure first that N001 is supporting the missile all the way. I've had enough of hearing missiles in DCS do not work, of course they are not perfect nor they should be, IMO.

 

Really? Perhaps I'm misunderstanding but, so far, I haven't seen anything to indicate that changing the PRF setting is actually changing the STT PRF. Or am I missing something. The only difference I see is on the back end. After the lock is dropped, being in either MPRF or ILV makes it easier for the radar to reacquire and relock. The same thing happens by waiting to change PRF until the lock is dropped. Though, in that case, reacquiring may take a fraction of a second more.

 

At what range did you run the test? away from my game now so can't run the TRK files you recently posted. If you haven't done so already, while in STT, try switching from HI to ILV first then MED because if you were not close enough to the target at the moment you changed to MED (early long range shot/early aspect shifting), you will lose STT.

 

Normally if you synchronize PRF to targets aspect dynamically, you should be able to avoid losing the lock all together (also stay lower than the target at all times).

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Outside of 30km you should stay in HI all the way. ILV won't help you either (because it's rear aspect is abysmal), that's the point I'm trying to make.

 

Besides, when do you see shots taken beyond that range? Only in super high flying environment. 99% of realistic engagements with any chance of a hit happen under 30km, hence MED PRF is the way to go...

 

Anyway, the best teacher is always lots of flight hours in MP, especially in a competitive squadron environment. That's when all those little things are truly put to the test again and again.

 

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Edited by Breakshot

 

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Ironhand, the PRF does change during STT, you can test it by switching to MED at beyond its range, say at 60km. You should lose STT lock...

 

Lock is maintained in the F-15 once in STT regardles of PRF even at max range headon.

In TWS however the bug is dropped if you change from HPRF to MPRF beyond 25NM.

 

EDIT: After fiddlng around with this a bit i tend to believe that once you have entered STT you are unable to change PRF anymore. STT will maintain the PRF you had when you entered STT.

Reason: In F-15 you can TWS bug a headon target in MPRF at 40NM but you can't go to STT. And as I stated before, if you STT lock a headon target at >40NM in HPRF and then change to MPRF you should loose the lock. But lock is maintained.

 

EDIT EDIT: I'm starting to suspect that STT does little more than tick on a flag like; if STT==1 then SARH_can_track_target. But its a different set of parameters that decide if your missile is gonna guide all the way to the target or not.

That might also be why we see AIM's wander off to track chaff dropped a year ago.

I have also seen AIM's guide perfect to an intercept despite that target was in a notch, MEM was blinking and TD box was not even on the bandit anymore.

 

From what I can gather from this, you should chose MPRF before entering STT to increase your chances of maintaining a lock on your target and cross your fingers for a succesful intercept.


Edited by Svend_Dellepude

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Yes, it is modeled differently for the F15. One way to test is to use radar reset button in STT. Then unlock target. For Flanker, the parameters would be reset, for F15 no change. However in TWS, PRF changes do work.

 

Certainly makes flying F15 more intuitive in that sense you don't have to worry once STT is established. But in TWS, you must enter MED at earliest convenience.

 

While basically for RuFor everything is modeled manually.

 

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Ironhand, the PRF does change during STT, you can test it by switching to MED at beyond its range, say at 60km. You should lose STT lock...

 

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I had tested that prior to starting this thread but the range was right around 60km. When the lock was wasn't broken, I made an assumption that was incorrect. Retested at 80km range and, the lock, indeed, dropped.

 

I hadn't fully appreciated the the effect that the proper PRF has on your ability to lock a target that you can otherwise "see" on radar. At a range where the same forward hemisphere target first becomes visible in ILV, HPRF, and MPRF (to use the West's designations), a lock can only be achieved with HPRF. The other two PRF settings won't lock until the range has decreased.

 

Wish I could find a way to get more sim time. There's so much that I'm missing now.

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I have also seen AIM's guide perfect to an intercept despite that target was in a notch, MEM was blinking and TD box was not even on the bandit anymore.

 

I've seen so many ERs hit me after the platform has been blown to hell that I'm starting to believe this is all magic. :D

 

While basically for RuFor everything is modeled manually.

 

I remember the good old days where you had to manually follow the target in TWS otherwise it would lose the bug when it went outside elevation limits. The funniest part is that almost none of the Eagle drivers knew about this.. :D

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I had tested that prior to starting this thread but the range was right around 60km. When the lock was wasn't broken, I made an assumption that was incorrect. Retested at 80km range and, the lock, indeed, dropped.

 

I hadn't fully appreciated the the effect that the proper PRF has on your ability to lock a target that you can otherwise "see" on radar. At a range where the same forward hemisphere target first becomes visible in ILV, HPRF, and MPRF (to use the West's designations), a lock can only be achieved with HPRF. The other two PRF settings won't lock until the range has decreased.

 

Wish I could find a way to get more sim time. There's so much that I'm missing now.

 

Cool! yeah we all have our phases... there is always something new to learn and discover

 

 

@Blaze, yeah man I actually preferred it that way, could use my elevation wheel for best effect... Now you have to digital step by step...

 

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