AIM-7MH enters HOJ even if target that is locked and fired on isn't jamming

[Hextopia]

Not sure if this is intended behavior, but AIM-7MH's shot at a target in STT that isn't jamming will guide to a nearby jamming target (even if that target is outside the radar's illumination and further away).  I can put together a mission and track if it's needed, but the fundamental question is, should the AIM-7MH be going into HOJ if there's a jammer in the seeker FOV, or is that something the aircraft commands?

[Northstar98]

1 hour ago, Hextopia said:

I can put together a mission and track if it's needed, but the fundamental question is, should the AIM-7MH be going into HOJ if there's a jammer in the seeker FOV, or is that something the aircraft commands?

I imagine yes, the seeker is completely passive and it just homes in on radiation (normally reflected from the target by the firing platform's RADAR, or if capable, radiation emitted by a jammer), so long as it's within the seeker FOV.

I don't think the AIM-7s (apart from maybe the P) has any kind of uplink to the missile, and I would guess that in the absence of a CWI/PDI signal, the missile falls back to its HOJ mode.

All of this is speculation on my part, so take this with a heaped tablespoon of salt.

Bear in mind also that for the most part DCS' implementation of jamming is very basic, and for the overhwelming most part, it's just continuous noise jamming (performing range denial in DCS) which is perfect for HOJ missiles.

IRL, for the modules that have ECM systems, they're probably mostly going to be DECM systems (probably mainly focused on track breaking and maybe defeating radio proximity fuses too), HOJ missiles should be less effective against these systems and the techniques they use because they don't transmit continuously, and in the case of track breakers, they only transmit when the jammer detects a RADAR in a track mode or fire control mode, if the lock is broken for whatever reason, the jammer stops transmitting until the RADAR reacquires.

Unfortunately the only jammers with this logic so far are ED's F/A-18C (which also has track breaking implemented) HB's F-14 (which has accurate transmit behaviour) and RAZBAM's Mirage 2000C (I think anyway).

There's also the fact that ED are trialling much improved seeker fidelity on the AIM-120, which will probably lay the ground work for other missiles, such as the AIM-7s.

Edited November 13, 2021 by Northstar98

[QuiGon]

2 hours ago, Northstar98 said:

I imagine yes, the seeker is completely passive and it just homes in on radiation (normally reflected from the target by the firing platform's RADAR, or if capable, radiation emitted by a jammer), so long as it's within the seeker FOV.

I don't think the AIM-7s (apart from maybe the P) has any kind of uplink to the missile, and I would guess that in the absence of a CWI/PDI signal, the missile falls back to its HOJ mode.

All of this is speculation on my part, so take this with a heaped tablespoon of salt.

Bear in mind also that for the most part DCS' implementation of jamming is very basic, and for the overhwelming most part, it's just continuous noise jamming (performing range denial in DCS) which is perfect for HOJ missiles.

IRL, for the modules that have ECM systems, they're probably mostly going to be DECM systems (probably mainly focused on track breaking and maybe defeating radio proximity fuses too), HOJ missiles should be less effective against these systems and the techniques they use because they don't transmit continuously, and in the case of track breakers, they only transmit when the jammer detects a RADAR in a track mode or fire control mode, if the lock is broken for whatever reason, the jammer stops transmitting until the RADAR reacquires.

Unfortunately the only jammers with this logic so far are ED's F/A-18C (which also has track breaking implemented) HB's F-14 (which has accurate transmit behaviour) and RAZBAM's Mirage 2000C (I think anyway).

There's also the fact that ED are trialling much improved seeker fidelity on the AIM-120, which will probably lay the ground work for other missiles, such as the AIM-7s.

 

ECM behaviour depends on the recieving aircraft (the aircraft that is being jammed) and how the ECM effects are implemented in this aircraft. On the transmitting side (the aircraft that is jamming), there is only a simple flag in the DCS code that gets set to true. It totally depends on the developers of the recieving aircraft how they implement the jamming effects.

The Hornet jammer is somewhat special in that regard, as it can indeed break locks of ground based radars. I don't think that works against (player controlled) aircraft. I think ED changed something on part of the AI (ground) units and how they react to the Hornet jammer.

[Northstar98]

12 minutes ago, QuiGon said:

ECM behaviour depends on the recieving aircraft (the aircraft that is being jammed) and how the ECM effects are implemented in this aircraft. On the transmitting side (the aircraft that is jamming), there is only a simple flag in the DCS code that gets set to true. It totally depends on the developers of the recieving aircraft how they implement the jamming effects.

Yes, but some aircraft (like the ones I mentioned) do have the transmitting behaviour accurate (AFAIK), even if the jamming itself is DCS' simple ECM = On, ECM = Off.

So for instance, in the Tomcat, even if the ECM mode is set to RPT, the ECM flag state is controlled realistically (unlike say, FC3 aircraft, where if you turn the ECM on the ECM flag is on, until you turn your ECM off) if that makes sense.

From the HB manual:

Quote

The AN/ALQ-100 and 126 jammers are designed to detect radar threats, analyze them, select the optimum countermeasure technique available and apply it. Available techniques for jamming are amongst others, mainlobe blanking, inverse con-scan, range-gate pull-off and swept square modes.

In real life these two systems differ greatly with the AN/ALR-126 being by far the most effective system. In DCS both are modelled as a simple noise jammers due to engine limitations but controlled by the DECM logic as to when it’s on or off and thus work the same.

AFAIK, inverse con-scan, range-gate pull-off and swept square wave are all track breaking techniques (I imagine the system is also capable of velocity gate pull-off and possibly some monopulse angle-deception technique, seeing as their predecessors were capable).

So if I understand correctly, if you fire a missile at the Tomcat and the missile is using a HOJ mode, if there isn't a RADAR locking the Tomcat, the ECM flag should remain off, even if the ECM mode is set to RPT, and thus the missile shouldn't track.

As a side note, with receivers, I wish they'd keep it consistent for certain ECM systems (FC3 aircraft seem to treat jammers as noise jammers, the Mirage 2000C as this weird multiple target repeater etc).

12 minutes ago, QuiGon said:

The Hornet jammer is somewhat special in that regard, as it can indeed break locks of ground based radars. I don't think that works against (player controlled) aircraft. I think ED changed something on part of the AI (ground) units and how they react to the Hornet jammer.

Yes, the Hornet jammer is so far the only jammer to actual employ a DECM technique (track breaking - designed to break lock-on), it does work against some AI aircraft (it certainly works against the MiG-23MLD). As for player aircraft, I guess that depends on ECM effects modelling on their respective RADARs, again this is something that needs improving and standardising IMO.

As another side note, ED refer to the Hornet's jammer as the AN/ALQ-165 which AFAIK didn't come to the legacy Hornet (instead using the AN/ALQ-126B

Edited November 13, 2021 by Northstar98

[QuiGon]

1 hour ago, Northstar98 said:

Yes, but some aircraft (like the ones I mentioned) do have the transmitting behaviour accurate (AFAIK), even if the jamming itself is DCS' simple ECM = On, ECM = Off.

So for instance, in the Tomcat, even if the ECM mode is set to RPT, the ECM flag state is controlled realistically (unlike say, FC3 aircraft, where if you turn the ECM on the ECM flag is on, until you turn your ECM off) if that makes sense.

I see what you mean and this is true indeed. Some aircraft just leave the ECM flag = On if they are turned on, while others change the state depending on recieving radiation.
 

1 hour ago, Northstar98 said:

the Mirage 2000C as this weird multiple target repeater etc

I guess that would be deception jamming.
 

1 hour ago, Northstar98 said:

Yes, the Hornet jammer is so far the only jammer to actual employ a DECM technique (track breaking - designed to break lock-on), it does work against some AI aircraft (it certainly works against the MiG-23MLD). As for player aircraft, I guess that depends on ECM effects modelling on their respective RADARs, again this is something that needs improving and standardising IMO.

I'm pretty sure that the break lock effect is not implemented on the Hornet's jammer, but on the AIs behaviour, how they react to the jammer. Unlike 3rd party devs ED does have control over the AI behaviour. That's why it doesn't work against player controlled aircraft.

Edited November 13, 2021 by QuiGon

[Northstar98]

2 hours ago, QuiGon said:

I see what you mean and this is true indeed. Some aircraft just leave the ECM flag = On if they are turned on, while others change the state depending on recieving radiation.

Exactly

I wonder if this is what's causing the AIM-120 behaviour when tracking the Tomcat, as in its homing in on the jammer, but then then the jammer turns off and the active RADAR seeker doesn't re-enable (for some reason), causing the missile to not track.

2 hours ago, QuiGon said:

I guess that would be deception jamming.

Yes, though it seems to be different than the example shown here (where the RADAR scope gets cluttered with contacts, essentially by exploiting sidelobes), with the Mirage 2000C there's a false contact that slowly migrates across the scope (I guess with each sweep), and the true contact is hidden (whereas in the example in the video, the true contact is still present, but there's just so many false contacts, you can't tell which is the true one).

I'm unsure what's happening in the Mirage's case, but I guess this is more something for people who actually know what they're talking about, unlike me.

Edited November 13, 2021 by Northstar98

[QuiGon]

37 minutes ago, Northstar98 said:

Exactly

I wonder if this is what's causing the AIM-120 behaviour when tracking the Tomcat, as in its homing in on the jammer, but then then it's turned off and the active RADAR seeker doesn't re-enable.

Yeah, that's also my suspicion:

On 11/1/2021 at 8:31 AM, QuiGon said:

I'm suspecting there might be an error in the code of the F-14 ECM (some code loop or so) causing the ECM flag to constantly switch between ON and OFF when the ECM is supposed to be actually transmitting. This "blinking behaviour" might be messing with the AMRAAM guidance logic, possibly causing it to constantly switch between different modes (active guidance <> HOJ guidance) and thus messing up it's guidance.

Obviously this is a lot of specualtion on my part as I don't know the code, but it might give an idea of what could be going on there.

Edited November 13, 2021 by QuiGon

[Hextopia]

I'm wondering moreso whether any jammer in the FOV of the AIM-7MH should be causing it to go into HOJ.  I had an instance where I fired an AIM-7MH at a target at ~5NM away, but the missile turned off target to track a friendly with their jammer on ~10NM away.

 

I'm fairly certain, even with an automatic HOJ logic in the missile, it'd still target and follow the much stronger radar return from the AWG-9 illuminating a target at 5 miles versus the lower power jammer further away.  If anything, it just seems like an additional check to look at relative radar return strength should happen to see if the original track is lost and HOJ is entered.

[henshao]

Just basic Sparrow info: the Sparrow is fed "radar video" from the launching aircraft so that it knows just what set of photons to be homing in on

 

unless a jammer is simulating the aforementioned radar, the sparrow should not be tuned to it. an illustration: Phantom A launches Sparrow A on Flanker A. Flanker B is jamming Hornet B. Because Sparrow A is tuned to Phantom A, and Flanker B is jamming Hornet B, Sparrow A should* not home-on-jam Flanker B because Flanker B's jammer is working on Hornet B's radar freq(s)

 

*it is more complex than this but in a perfect world this holds true