F-15C radar changes

[henshao]

the APG-63 for the F-15 was underperforming. The thread for that bug was recently locked. In the latest patch I notice no increase in detection range however my F-15 wingman is reporting contacts at 150 miles and seemingly beyond. I think ED touched the Eagle's radar but made a mistake somewhere.

[Nahen]

What's your altitude and speed?
What target height and speed?
What aspect of the goals?
And what are the most important goals?
Below are some screenshots
- first target detected - Tu-95 detection distance> 140 nM / altitude ~ 36,000 / speed ~ 300 knots,
- next target - MiG-31 detection distance ~ 75 nM / altitude ~ 30,000 / speed ~ 450 knots,
- next target - Tu-160 detection distance ~ 85 nM / altitude ~ 39,000 / speed ~ 450 knots,
- last detected target - Su-27 detection distance ~ 65 nM / altitude ~ 34,000 / speed ~ 450 knots.

What do you think is wrong with your detection??

 

 

And one more thing - the AI winger? Is AWACS friendly nearby? If there is AWACS, the "AI" wingman can give you the designations/bearing he got from AWACS.

[Vekkinho]

On 6/23/2022 at 8:51 PM, henshao said:

the APG-63 for the F-15 was underperforming. The thread for that bug was recently locked. In the latest patch I notice no increase in detection range however my F-15 wingman is reporting contacts at 150 miles and seemingly beyond. I think ED touched the Eagle's radar but made a mistake somewhere.

Bear in mind that AI Wingmen report airborne contacts based on RWR spikes not just radar picture.

[henshao]

5 hours ago, Vekkinho said:

Bear in mind that AI Wingmen report airborne contacts based on RWR spikes not just radar picture.

Interesting, then, that he was giving me the range (150)

[Nahen]

13 hours ago, Vekkinho said:

Bear in mind that AI Wingmen report airborne contacts based on RWR spikes not just radar picture.

How did the wingman determine the distance to the target based on the RWR?

[Vekkinho]

1 hour ago, Nahen said:

How did the wingman determine the distance to the target based on the RWR?

 

 

9 hours ago, henshao said:

Interesting, then, that he was giving me the range (150)

He might be relaying AWACS calls.

[draconus]

9 hours ago, Vekkinho said:

He might be relaying AWACS calls.

I'm pretty sure it's AWACS' job to relay that info and when a wingman calls bandits it's from AI radar detection.

[Nahen]

And here comes some of the questions I asked earlier:

- what purpose?
- what altitude of the target?
- what altitude of the AI wingman?
- what aspect and speed?

An artificial wingman should in theory not call targets smaller than a bomber, AWACS, tanker etc with a distance greater than 80-90nM. So if he gave a bearing on said "big" machines, he could do it.

If it gave a 150 - mile distance - which turned out to be a jetfighter - it means that, as in every game, AI "sees better / farther" than human-guided machine systems.

[henshao]

I'm still trying to replicate the issue I haven't been on DCS much

[GGTharos]

@BIGNEWY is there any news on this?   Documentation has been supplied, no changes have been made and nothing has been said about this.  Again this is a very easy change but it appears to be getting forgotten.

[F-2]

 

[Cmptohocah]

18 hours ago, F-2 said:

 

Nice video, but also a little bit of propaganda. It suggests that Eeagle's radar can't be notched, which is not true as described by real F-15 pilots.

[henshao]

10 minutes ago, Cmptohocah said:

Nice video, but also a little bit of propaganda. It suggests that Eeagle's radar can't be notched, which is not true as described by real F-15 pilots.

When the F-15's radar goes into Medium PRF track, it is very notch resistant, utilizing both range-gate and velocity gate and more, but of course nothing is perfect. As I have pointed out in other threads, when the target is both very low and with little to no closure, there is very little to separate it from the actual ground from a radar perspective.

 

That being said, historically no F-15 was delivered without having its ability to track a target through a look-down no-closure situation first verified by McDonnell

[GGTharos]

28 minutes ago, Cmptohocah said:

Nice video, but also a little bit of propaganda. It suggests that Eeagle's radar can't be notched, which is not true as described by real F-15 pilots.

Here's another bit of non-propaganda propaganda for you then:  This is the original APG-63, in the F-15C the worst tuned MSIP radar performed as well as the best tuned original radar, all according to real pilots as well.

It's definitely notchable as seen in real combat, but also in real combat this has rarely been an issue - why?  We don't really know.

[Cmptohocah]

2 hours ago, Gahab141 said:

Which radar had been often notched in combat? Real life isn't a game, real rwrs aren't as precise as in DCS

F-15C's during "Dessert storm" by Iraqi pilots.

You don't need RWR to notch a radar, in fact SPO is next to useless for this.

It's enought to know the emitting radar's heading, which you can use your own radar for.

RWR is DCS is a bit arcady.

P.S. you can use a data-link also if available

Edited August 18, 2022 by Cmptohocah

[GGTharos]

3 hours ago, Cmptohocah said:

F-15C's during "Dessert storm" by Iraqi pilots.

You don't need RWR to notch a radar, in fact SPO is next to useless for this.

Often failed to notch, not often notched.   Yes, there were situations where the initial geometry was bad but that wasn't a deliberate act.

[Cmptohocah]

3 hours ago, nukeproof said:

Dessert =

Ahahahahahaahah, I could not stop laughing.

2 hours ago, GGTharos said:

Often failed to notch, not often notched.   Yes, there were situations where the initial geometry was bad but that wasn't a deliberate act.

Not according to the pilot that encountered it. He specifically said that the MiGs went into notch preciselly at a distance at which the Eagle's radar was most prone to it. I will see if I can digg up this interview...

[GGTharos]

Yes look up the event, I know what you're talking about.   It's not the simple fact you stated

[Nahen]

Try to notch the F-15 radar when it is flying straight at you above 2 Ma ...
What is notch? This is the drastic change in the speed of the target relative to the radar and "blending in with the background". When the radar is flying faster than Mach 2, even when you are flying perpendicular to it, the radar speed is still enough to separate and keep the target in the background.
If someone attack in F-15 at speeds around Mach 1 --- well its his problem...

[Cmptohocah]

6 hours ago, GGTharos said:

Yes look up the event, I know what you're talking about.   It's not the simple fact you stated

Here you go:

 

Shame we don't have cell resolution implemented in DCS

[henshao]

Without getting into too much detail about these systems, the F-15s were almost certainly in High PRF track (lock) when they got notched on that steep lookdown beam maneuver, because their selected weapon was the Sparrow which requires HPRF for guidance. Whether it would have worked against Medium PRF, who's to say (I doubt it) but it does highlight another rarely mentioned advantage of the AMRAAM, beyond launch-and-leave capability: the ability to stay in Medium PRF track for target prosecution

 

Spoiler

As I am reading the timeline of events in Debrief a Complete History of U.S. Aerial Engagements - 1981 to the Present (Brown, Craig), the Eagles locked up the Fulcrums at about 25 miles, at which point the Fulcrums "initiated a beam maneuver" and then took a course towards their base. It sounds to me more like they detected they were spiked by the Eagles and just decided to turn around and go home (the strike aircraft they were launched against were already headed home). At this time, another group of Fulcrums popped up at less than 15 miles, nose on the Eagles which were in pursuit of the first group of Fulcrums moving away. It seems like a typical Soviet/Iraqi "drag and bag" tactic where one group is basically baiting the enemy for another group to exploit.

While the second Fulcrum group lead prosecutes the Eagle lead, he is killed by Eagle wingman. They form up at very low altitude heading away from the area when second Fulcrum group wingman is announced by AWACS to be in pursuit. The Eagles turn around, apparently to the Fulcrum's ignorance, and split up to simultaneously visually ID their pursuer and take position to attack him. When "Rico" passes underneath and is certain the other jet is Iraqi, he maneuvers hard to get on its six. The unaware Fulcrum finally gets wise just before "Rico" is in "the elbow position" and starts to turn hard. Our beloved, underrated F-15 however is not so easily outturned; after a time, Rico is finally in position to shoot, nose-on at the bandit's six o'clock. At only 1000 feet above the ground, the Fulcrum attempts a Split-S, but even a Mig-29 cannot complete such a maneuver with such little airspace and flies into the ground.

 

[GGTharos]

3 hours ago, Cmptohocah said:

Here you go:

 

.... and we start to pick them up as they're in their beam maneuver (he alludes to but does not describe the counter).  So great, you found one of the few times this happened

 

3 hours ago, Cmptohocah said:

Shame we don't have cell resolution implemented in DCS

I don't know if there was something said about this in the rest of the video, but it has nothing to do with the notch.

[Cmptohocah]

8 hours ago, GGTharos said:

 

.... and we start to pick them up as they're in their beam maneuver (he alludes to but does not describe the counter).  So great, you found one of the few times this happened

 

I don't know if there was something said about this in the rest of the video, but it has nothing to do with the notch.

I agree it has nothing to do with the notch, it's just that he mentions it before the notch part and it reminded me that we have perfect binary radar acquisition in DCS. It would be great if we had some sort of radius inside which you can't really tell how many targets are there.

Another pair of Eagles, had the same issue in '99 against the Fulcrums as they initially taught there is only one there until they got separated enough and/or Eagles got close enough to be able to discriminate between the two.

10 hours ago, henshao said:

Without getting into too much detail about these systems, the F-15s were almost certainly in High PRF track (lock) when they got notched on that steep lookdown beam maneuver, because their selected weapon was the Sparrow which requires HPRF for guidance. Whether it would have worked against Medium PRF, who's to say (I doubt it) but it does highlight another rarely mentioned advantage of the AMRAAM, beyond launch-and-leave capability: the ability to stay in Medium PRF track for target prosecution

 

  Reveal hidden contents

As I am reading the timeline of events in Debrief a Complete History of U.S. Aerial Engagements - 1981 to the Present (Brown, Craig), the Eagles locked up the Fulcrums at about 25 miles, at which point the Fulcrums "initiated a beam maneuver" and then took a course towards their base. It sounds to me more like they detected they were spiked by the Eagles and just decided to turn around and go home (the strike aircraft they were launched against were already headed home). At this time, another group of Fulcrums popped up at less than 15 miles, nose on the Eagles which were in pursuit of the first group of Fulcrums moving away. It seems like a typical Soviet/Iraqi "drag and bag" tactic where one group is basically baiting the enemy for another group to exploit.

While the second Fulcrum group lead prosecutes the Eagle lead, he is killed by Eagle wingman. They form up at very low altitude heading away from the area when second Fulcrum group wingman is announced by AWACS to be in pursuit. The Eagles turn around, apparently to the Fulcrum's ignorance, and split up to simultaneously visually ID their pursuer and take position to attack him. When "Rico" passes underneath and is certain the other jet is Iraqi, he maneuvers hard to get on its six. The unaware Fulcrum finally gets wise just before "Rico" is in "the elbow position" and starts to turn hard. Our beloved, underrated F-15 however is not so easily outturned; after a time, Rico is finally in position to shoot, nose-on at the bandit's six o'clock. At only 1000 feet above the ground, the Fulcrum attempts a Split-S, but even a Mig-29 cannot complete such a maneuver with such little airspace and flies into the ground.

 

Is medium pulse repetition frequency more resistant to notching? If so, I would be very happy to learn why.

[Spurts]

14 hours ago, Cmptohocah said:

Shame we don't have cell resolution implemented in DCS

Not with a SSM, so not with FC3 aircraft, but many other aircraft do have cell resolution modeled.  It's not a blanket DCS statement.

[henshao]

  

7 hours ago, Cmptohocah said:

I agree it has nothing to do with the notch, it's just that he mentions it before the notch part and it reminded me that we have perfect binary radar acquisition in DCS. It would be great if we had some sort of radius inside which you can't really tell how many targets are there.

Another pair of Eagles, had the same issue in '99 against the Fulcrums as they initially taught there is only one there until they got separated enough and/or Eagles got close enough to be able to discriminate between the two.

Is medium pulse repetition frequency more resistant to notching? If so, I would be very happy to learn why.

Obviously we are very proud of the F-15 over here, so a little history first: One of the most important demands of the USAF on the FX (ultimately F-15) was one-man operation of the aircraft, avionics included. Without the dedicated RIO of the Phantom and Tomcat, the what would become the APG-63 had to be that much more intelligent at picking out the real target from the clutter, jamming, and so on. Hughes beat out Westinghouse for the FX radar program when they deliver a set capable of Medium PRF: AFAIK the very first airborne set in the world capable of this data-intensive mode, and in 1972-1973 no less. So what is medium PRF as implemented in the F-15? It's an extraordinarily complex topic which is not my forte, so I can only offer a cursory explanation. I expect you already know most of this.

In high PRF, the radar is running as hard as it can to detect targets. Maximum energy downrange on contacts (while the antenna is sweeping, it will hit a potential contact many many times, allowing many chances to distinguish signal from noise). The amount of filtering it can do is limited by the speed of the electronics behind it, but this mode provides the best detection distance. Range data will be highly ambiguous and must be determined some other way. Often there is limited or no capture of targets moving away, and inherently this mode filters out stationary objects (the ground)

In low PRF, the radar is working almost like a sonar. Ping, echo, ping, echo. Ranging of contacts will be very accurate but overall energy output is low and detection distance suffers greatly. Additionally it is very difficult to tell what is moving and what is not.

In medium PRF, the radar is only going as fast as it can allow a ton of extra signal processing. Usually the maximum realistic detection distance of this mode in fighter aircraft will be in the neighborhood of 40 miles. This still generates more radar energy on contacts (better detection distance) than a low PRF mode, while signal processing allows accurate determination of relative speed and distance. The latter part is key. In medium PRF, a target which is not moving faster than the ground in relative terms (a "beaming" aircraft) can still be determined to be much closer than the ground behind it. Hence the radar is not "fooled."

 

From a systems perspective, normally the APG-63 will automatically transition to Medium PRF track when the target signal is strong enough. However, in the Desert Storm encounter in the video above, the target was being tracked in High PRF despite the close range, overriding normal logic to support an imminent AIM-7 launch. If a "range gate" was being employed at all, it was a very large one. When the target Mig-29 turned perpendicular, the radar no longer had enough doppler shift it needed to distinguish the target from the ground, and lost track. However, as GGTharos pointed out, when the radar returned to search, it either went into an interleaved pattern (HPRF, MPRF, HPRF, MPRF) or the pilot selected an all MPRF search, and the radar immediately picked the contacts back up in their beaming maneuver. This was probably because 1) their doppler shift was small, but still present, and 2) at medium altitude flying over the desert, the targets were some 2 miles closer to the radar than the ground behind them.

 

Here is Hughes' take on such matters, from way back in the original version of the APG-63. The Desert Storm PSP+MSIP F-15s were much, much improved.

Spoiler