S-400 and F-35

[ricnunes]

We seem to be talking at cross-puposes. I am asking if opposing forces can geolocate an IFF signal coming from an F-22's transponder not if friendly ATC can geolocate it.

So a scenario is that a friendly AWACS or ground based radar interrogates the F-22's transponder. The transponder sends out the appropriate encrypted response as intended. Can that response be detected by opposing forces and, without being decrypted, the signal used to geolocate the F-22? Does IFF potentially compromise F-22 (and F-35 for that matter) stealth?

And like I've been telling/hinting, it's highly unlikely that an enemy force can detect, let alone geolocate a transmission from an IFF transponder (doesn't matter which aircraft its fitted in) resulted from a positive challenge/interrogation from another friendly asset, this for all the reasons that I previously mentioned and of course from the way that an actual IFF works.

[boogieman]

I suppose detecting the IFF emissions would be plausible, but since they are transient I doubt they would be of much use to OPFOR. At best they might get some idea of where the jet was when it emitted them, but that info would be almost instantly out of date for a tactical fighter doing ~Mach 1 and potentially changing course/maneuvering etc.

[aussiebloke]

I suppose detecting the IFF emissions would be plausible, but since they are transient I doubt they would be of much use to OPFOR. At best they might get some idea of where the jet was when it emitted them, but that info would be almost instantly out of date for a tactical fighter doing ~Mach 1 and potentially changing course/maneuvering etc.

Transient perhaps but sufficient to cue several active radar homing missiles to that vicinity that then can commence their own search?

I found this quote interesting:

Active IFF systems—the most obvious examples are radars and question-and-answer systems— can have longer range but they, of course, might be detected, providing the enemy information about friendly forces. This risk can be minimized by transmitting the least power necessary, transmitting intermittently, using and looking for special transmission patterns (or “waveforms’ known only to other friendly forces, and so on.

https://www.princeton.edu/~ota/disk1/19 ... 935105.PDF

[hornetfinn]

I suppose detecting the IFF emissions would be plausible, but since they are transient I doubt they would be of much use to OPFOR. At best they might get some idea of where the jet was when it emitted them, but that info would be almost instantly out of date for a tactical fighter doing ~Mach 1 and potentially changing course/maneuvering etc.

Transient perhaps but sufficient to cue several active radar homing missiles to that vicinity that then can commence their own search?

Probably not in any case as missiles are not very good at searching large volumes of airspace. Their radars are too small and there is far too short time to scan any larger air space. So the targeting info should be extremely precise and up to date for missiles succeed. IFF transmissions are short and not frequent, so it's hard to get accurate targeting info. Besides, that info very quickly becomes obsolete because the aircraft that sent them will be somewhere else with likely different heading, altitude and speed.

[wolfpak]

Didn't Combat Tree on board EC-121's and F-4D's exploit the North Vietnamese IFF transmissions?

Earlier in this thread is was noted that the ARRGM-ER was entering LRIP. Did they flight test it yet? ////////

[ricnunes]

Didn't Combat Tree on board EC-121's and F-4D's exploit the North Vietnamese IFF transmissions?

I never seem to have read about that.
But in case that has happened and looking at the era (Vietnam War) it's quite possible that those North Vietnamese IFF were very simple and unencrypted devices and as such the Americans could have "easily" developed an interrogator in order to 'constantly' interrogate the North Vietnamese IFFs and thus know where their Migs were roughly located at (but never to aim or shoot missiles at those same Migs). Nonetheless those early and old IFFs would have been a far cry from more modern, advanced and encrypted IFF systems such as Mode 4.

[spazsinbad]

Flight Tests Of Extended Range AARGM Expected In Fiscal 2021
06 May 2019 Calvin Biesecker

"NATIONAL HARBOR, Md.–Captive carry-testing of an extended-range variant of the Navy’s anti-radiation missile is expected to begin in fiscal year 2020 and be followed by flight-testing some time in FY ’21, a service official said on Monday...."

Source: https://www.defensedaily.com/flight-tes ... navy-usmc/

[basher54321]

Didn't Combat Tree on board EC-121's and F-4D's exploit the North Vietnamese IFF transmissions?

I never seem to have read about that.
But in case that has happened and looking at the era (Vietnam War) it's quite possible that those North Vietnamese IFF were very simple and unencrypted devices and as such the Americans could have "easily" developed an interrogator in order to 'constantly' interrogate the North Vietnamese IFFs and thus know where their Migs were roughly located at (but never to aim or shoot missiles at those same Migs). Nonetheless those early and old IFFs would have been a far cry from more modern, advanced and encrypted IFF systems such as Mode 4.

Combat Tree could supposedly interrogate the Soviet SRO-2 that was exploited via many sources in the 60s. It was operated from the late 60s in secret on EC-121s but in 1972 was used on F-4D/Es to verify and fire AIM-7s at MiGs BVR.

One thing was the SRO had to be switched on and the VPAF likely got wise to it - slight problem was their GCI needed the SRO on so they could see and guide them. Yes ancient technology and likely not as easy to do anymore.

[aussiebloke]

Didn't Combat Tree on board EC-121's and F-4D's exploit the North Vietnamese IFF transmissions?

By the late 1960s, U.S. forces were taking steps to solve the BVR IFF problem. The first was enabled by covert exploitation of Soviet SRO-2 IFF transponder equipment recovered by the Israelis from MiGs shot down during the 1967 Six-Day War. In 1968 the USAF started a program known as Combat Tree to build and incorporate a suitable SRO-02 interrogator into U.S. fighters. By 1971 a suitable system had been designed, tested, and fitted to a number of USAF F-4D aircraft. Known officially as the AN/APX-81, the system could be used in a passive mode where it received and processed IFF replies sent from MiGs in response to their own Ground Controlled Intercept (GCI) radar interrogations, or it could be used in active mode to trigger the MiGs response. A Combat Tree-equipped F-4 could positively identify enemy aircraft at up to 60 nm, three times farther than the F-4 could detect, but not identify, them with its radar alone.

Page 18 of https://csbaonline.org/uploads/document ... eport-.pdf

[Gums]

Salute!

Don't tink as many planes had the Tree gear as some tink. Even in 1972.

Except for a very few cases, a visual was required by the ROE. So the BVR capability was thwarted except for new tactics such as "shooter-eyeball". The AIMVAL-ACEVAL guys in our cadre at Hill talked about it. Trouble was the "eyeball" also had to have other cojones. Since the Vee rarely, if ever, tried a HO radar missile, the tactic worked. Biggest problem was getting separation the eyeball and the bandit, but the shooter was locked up already, and if the bandit blew thru a HO was possible.

OTOH, Teaball was very good and made a huge difference in our overall situtational awareness during the end game. On one of my few trips to Bullseye during the Christmas blitz, we got a call on either strike or guard freq when about 75 or 80 miles out, and greening up " Two bandits on end of runway at Yen Bai" ( could have been Phuc Yen).

Disco, Red Crown, the EW folks out over the Gulf and the fusion center at NKP did outstanding work. If we had kept the site at Lima Site 85, it would have been even better. But the Vee wanted that place very much, and it fell in early 1968.

http://aviationtrivia.blogspot.com/2011 ... -real.html

Gums sends...

[boogieman]

I suppose detecting the IFF emissions would be plausible, but since they are transient I doubt they would be of much use to OPFOR. At best they might get some idea of where the jet was when it emitted them, but that info would be almost instantly out of date for a tactical fighter doing ~Mach 1 and potentially changing course/maneuvering etc.

Transient perhaps but sufficient to cue several active radar homing missiles to that vicinity that then can commence their own search?

Probably not in any case as missiles are not very good at searching large volumes of airspace. Their radars are too small and there is far too short time to scan any larger air space. So the targeting info should be extremely precise and up to date for missiles succeed. IFF transmissions are short and not frequent, so it's hard to get accurate targeting info. Besides, that info very quickly becomes obsolete because the aircraft that sent them will be somewhere else with likely different heading, altitude and speed.

Exactly. Trying to get one or more active radar homing missiles to reliably find and track a VLO target would be a nightmare even with a high quality radar lock because the effective range of the missile seekers would be so drastically reduced. Trying to employ them on the basis of a brief IFF "chirp" would be a guaranteed waste of perfectly good missiles

[outlaw162]

We had tree in all our hand me down F-4Ds (at least 24). Even with it, it still took a considerable amount of 'tilt & gain' finesse (analog radar) to be able to actually shoot anything at the return. Our ex C-5 navigator WSOs often struggled for finesse. Hats off to those folks that used it effectively back then.

Actually better for mode 3 collision avoidance in its twilight.

[ricnunes]

Thanks basher54321 and aussiebloke for the info about Combat Tree!

And also thanks Gums and outlaw162 for your real life first hand stories and experiences!

[spazsinbad]

Back in the dreamiest of dream times 23 Jun 2014 'BP' had a few clues for us about COMBAT TREE brudda:

viewtopic.php?f=22&t=25662&p=273905&hilit=Combat+Tree#p273905

[spazsinbad]

07 Apr 2020 USS FORD IFF in ACTION: https://www.navy.mil/submit/display.asp?story_id=112565

"...Ford’s first certification of integrated combat systems tested the Air Traffic Control Radar Beacon (ATCRB) and Identification of Friend or Foe (IFF). The tests, conducted over several days, evaluated the ATCRB’s ability to track air and surface contacts and to identify friendly and enemy aircraft using an advanced identification system. IFF is used not only for positive, secure, friend identification, but also to control aircraft.

“We use an interrogator system to challenge aircraft transponders for identification,” said Operations Specialist 2nd class Juannietagrace Okeli, from Moss Point, Mississippi. “The interrogator, cooperative engagement capability, and the Ships Self-Defense Systems (SSDS) work together to provide us the combat identification.”..."