Question about Pulse Modes and break-lock

[SgtPappy]

I was flying as RIO with a buddy versus other friends in a practice session when I realized that pulse locks did not seem to be broken once range was within, say 15 nm or so. We were looking down from ~12000 ft over flat land on the Caucasus map with the target being a Hornet right on the deck, cold, beaming, S-turning, pumping chaff. We tried a few more times and another friend also could not break pulse lock in look down conditions at ~ 10 nm in the Viper.

 

I'm not sure if this is a bug, but the intent of this post is to ask if others have had similar experiences and if this is an accurate scenario. Is the resolution cell of the AWG-9 at 10 nm so tight that a pulse lock can be maintained? I did so prelim calculations and at that distance, the angular resolution cell length is around 2200 ft (2.1 deg. beamwidth for 3 cm wavelength and AWG-9 array diameter ~= 0.91 m). Assuming chaff takes 1/2 a second to bloom to a large RCS (~30 dBsm or so) and the defending target is beaming at 400 kn, you'd have a bunch of fully-bloomed chaff in the res cell for over a second - and a constant stream should throw off a pulse track of the RCS centroid. 

 

Obviously, there's more to it than this but if it's realistic, that's awesome! But I have a sneaking suspicion it might not be unless there's something special about the AWG-9 pulse modes in tracking I'm missing. If people want to see tracks/tacview, I'll setup an experiments with my buddies this week.

 

Thoughts?

 

Edited October 4, 2021 by SgtPappy

[IronMike]

in STT ground clutter isn't really an issue (finding him is), remember the "radar beam" being more or less fully concentrated on the locked aircraft. And thus indeed PSTT is one of the strongest locks, and once you got him, he can do whatever he wants, it will be almost impossible to break the lock. It is my go to mode when pushing on someone within I would say 25nm. And yes, it is realistic. A caveat: chaff has no effect on radars (so far). If chaff would be modeled better in the future, we might implement effects, depending on feasibility.

[SgtPappy]

1 hour ago, IronMike said:

in STT ground clutter isn't really an issue (finding him is), remember the "radar beam" being more or less fully concentrated on the locked aircraft. And thus indeed PSTT is one of the strongest locks, and once you got him, he can do whatever he wants, it will be almost impossible to break the lock. It is my go to mode when pushing on someone within I would say 25nm. And yes, it is realistic. A caveat: chaff has no effect on radars (so far). If chaff would be modeled better in the future, we might implement effects, depending on feasibility.

Thanks IronMike. Yea, I understand that the main beam is concentrating on the target. And indeed, without chaff, the STT range and angular gates keep the target locked and tracked at even longer ranges in a look-down scenario. When alone and without a RIO, it's a lot of fun to use PSTT on someone at 20 nm and just loose a BRSIT AIM-54 at them as they close!

 

However, the above is not what I'm unsure about - and please correct me if I'm wrong here: It really would be the chaff in the resolution cell that should cause the break lock from a PSTT (given a wide enough res cell) and that cell seems pretty wide in azimuth/elevation at 15 or even 10 nm (thousands of feet) so I believe here that's where chaff should cause the break-lock. Understandable that the current DCS engine prevents this in the F-14 and it is not currently modeled. I believe the FC3 modules will just do the dice roll thing which is how I think it works with all missiles in-game. This isn't really an argument to request that feature now, it's just a discussion I want to have to understand the real-world effect in comparison with the game.

Edited October 4, 2021 by SgtPappy

[DSplayer]

5 hours ago, IronMike said:

in STT ground clutter isn't really an issue (finding him is), remember the "radar beam" being more or less fully concentrated on the locked aircraft. And thus indeed PSTT is one of the strongest locks, and once you got him, he can do whatever he wants, it will be almost impossible to break the lock. It is my go to mode when pushing on someone within I would say 25nm. And yes, it is realistic. A caveat: chaff has no effect on radars (so far). If chaff would be modeled better in the future, we might implement effects, depending on feasibility.

On the topic of STTing someone, how well would PD-STTing someone with the MLC off fair in similar conditions to what @SgtPappy laid out? Would locks still be lost if they enter the notch in a look down situation or is it supposed to maintain track even when they’re notching?

Edited October 4, 2021 by DSplayer

[SgtPappy]

6 hours ago, DSplayer said:

On the topic of STTing someone, how well would PD-STTing someone with the MLC off fair in similar conditions to what @SgtPappy laid out? Would locks still be lost if they enter the notch in a look down situation or is it supposed to maintain track even when they’re notching?

 

My understanding from the limited amount of studying I've done so far is that once you have lock, the enemy can't do much to escape just by maneuvering. Clutter would have to be introduced into the range cell, while sidelobe return would have to be strong or jamming strength over target signal strength would have to be high - basically a low S/N ratio plus clutter in the mainlobe that's tracking the target.  Then all that needs to be in combination with low radial speed and maneuvering in the beaming plane of motion to deny the possible transition to PDSTT and broken lock search patterns.

 

In TWS with the MLC filter off, the effect would be lots of false returns, so it would make sense to switch to pulse search and use the DDD to lock the target. If locked already in PSTT, I assume the MLC filter on or off would have no effect. 

 

Hard locks (STT, as opposed to TWS "soft locks") are very strong and can't really be broken by maneuvering and just entering a notch which would normally deny Doppler information as IronMike mentioned. This is one issue with some modules like the F-15/FC3 fighters where lock is broken even in a look-up, 1 nm situation as long as the target has low radial speed. If you have lock, you don't even need Doppler return anymore as you did in search since the tracking gates in elevation, azimuth and range are keeping the radar looking at the target (notwithstanding loft calculations, just looking at automatic tracking). 

Edited October 4, 2021 by SgtPappy

[DSplayer]

2 hours ago, SgtPappy said:

My understanding from the limited amount of studying I've done so far is that once you have lock, the enemy can't do much to escape just by maneuvering. Clutter would have to be introduced into the range cell, while sidelobe return would have to be strong or jamming strength over target signal strength would have to be high - basically a low S/N ratio plus clutter in the mainlobe that's tracking the target.  Then all that needs to be in combination with low radial speed and maneuvering in the beaming plane of motion to deny the possible transition to PDSTT and broken lock search patterns.

 

In TWS with the MLC filter off, the effect would be lots of false returns, so it would make sense to switch to pulse search and use the DDD to lock the target. If locked already in PSTT, I assume the MLC filter on or off would have no effect. 

 

Hard locks (STT, as opposed to TWS "soft locks") are very strong and can't really be broken by maneuvering and just entering a notch which would normally deny Doppler information as IronMike mentioned. This is one issue with some modules like the F-15/FC3 fighters where lock is broken even in a look-up, 1 nm situation as long as the target has low radial speed. If you have lock, you don't even need Doppler return anymore as you did in search since the tracking gates in elevation, azimuth and range are keeping the radar looking at the target (notwithstanding loft calculations, just looking at automatic tracking). 

 

Okay. Just wondering since when using PD-STT with the MLC off against a target in a look down situation, they can notch and still cause a loss of lock. But, if I’m understanding what you’re saying correctly, the lock shouldn’t be broken in that situation. Sorry if I’m misunderstanding what you’re explaining.

[SgtPappy]

1 minute ago, DSplayer said:

Okay. Just wondering since when using PD-STT with the MLC off against a target in a look down situation, they can notch and still cause a loss of lock. But, if I’m understanding what you’re saying correctly, the lock shouldn’t be broken in that situation. Sorry if I’m misunderstanding what you’re explaining.

I'm just speaking very generally from a radar-theory perspective for pulse locks. Now that you mention it, maybe the AWG-9 requires Doppler return to maintain lock in PDSTT and that's why you need to switch to PSTT if the target starts to beam.