Re: Russian ECM
Snapshot said:
Thank you very much Overscan,
I've got my answer. So prior to the Su-35 or MiG-35 models, no Russian aircraft seemed to have the equivalent of the US AN/ALQ-100, -126 or -126B used by early and later models of F-14 and F-18.
No
fighter had built in ECM except MiG-29 9.13 onward. Su-24 had built in ECM. Bombers had built in ECM.
These systems use DRFM as you say.
No, only the last versions e.g. AN/ALQ-126B used DRFM I believe.
The technical terms I've found are: range-gate pulloff, swept-square wave, inverse conical scan and VGPO. The aim being to manipulate the oncoming radar's signal, generate a false timing and angular error in the radar return, leading to the radar beam shifting off the target. These systems are well described in Dennis R. Jenkins's book about the F-14 (Aerofax).
Range-gate pulloff, swept-square wave, inverse conical scan and velocity gate pull off are basic deceptive track-breaking ECM techniques used for a long time (1950s through 1970s) against SAMs. Inverse conical scan works against conical scan radars only. Swept square wave is used against conical scan radars with ECCM measures like LORO (e.g. later SA-2s). RGPO and VGPO are used for track-breaking against monopulse radars like SA-6.
In BVR engagements this deceptive jamming capability is a must-have to complement the effects of chaff and maneuvering, though modern Western radars, well before the advent of PESA and AESA radars may have well be resistant to (or at least could have limited the effects of) any such ECM had the Russians ever developed it.
The Soviet Union did produce some excellent ECM systems. In terms of aircraft they were hindered by weight and volume constraints. They concentrated on systems for strike aircraft as the most likely to be engaged by SAMs. Onboard ECM for fighters was considered from the beginning of MiG-29/Su-27 generation but only seemed to become urgent post Beka'a Valley (1982). Gardeniya was a quick hack system derived from existing systems with limited effectiveness especially in early versions; Sorbstiya an attempt to match western pods in capability.
Internal ECM systems can be a pain as it is harder to upgade them - if new antennas are needed, its a major overhaul, as opposed to bolting on a new pod. Non-stealth aircraft increasingly went the pod route, IMHO. For the Su-27 and its derivatives, sacrificing wingtip stations is a sensible tradeoff.
To me, self-protection "active jamming" refers to the copying of the signal and then the generation of false/additional misplaced radar echoes, in response to a radar pulse. Deception jamming comes into play once a lock-on is obtained. This is the way I got the whole (and complex) thing.
No.
Active is just contrasted to passive. Passive is e.g. chaff. The distinction I think you mean is noise jamming versus deception jamming.
Noise jamming is like broadcasting "white noise", it is used to drown out the real target return. This requires serious amounts of power and is normally used on dedicated jamming aircraft for this reason.
Deception jamming in contrast takes the incoming signal and processes it in some way to give misleasding information and sends it back. It requires much less power but more processing power. Earlier deception jammers used analogue signal processing. DRFM jammers use fully digital signal processing. Both can use a variety of additional techniques than those mentioned above e.g.
Blinking.
Noise or a sample of the victim radar pulse is broadcast intermittently between two widely separated transmitters e.g. wingtips or even different aircraft of a formation.
Terrain bounce.
This is typically used by low flying strike aircraft - it bounces the ECM signal off the ground. Typically used to defeat radar homing missiles possibly even with home-on-jam capability, the idea is they will home in on the reflected signal which is coming from the ground rather than the plane. Can be used for noise or deception jamming as above.
Cross Polarisation
This processes the signal to produce a cross polarised return signal. Vertically polarised component retransmitted as horizontally polarised, etc. This can break track on certain radars.
Crosseye (phase front distortion).
Two widely spaced locations (such as the nose and tail or two wingtips in the case of an aircraft) have interconnected transponders installed. Each of a pair of these locations normal to the direction of the victim radar receives the victim radar pulse and triggers the transponder on the opposite side of the unit, which then transmits a copy of the victim radar pulse with a 180 degree phase shift. The result is a reversal of the sign of the angular error measured at the victim radar. This causes the radar positioning mechanism to drive in the wrong direction. In the case of a TWS radar or active tracking radar, this technique can result in errors in positioning tracking gates in azimuth and elevation; can prevent the establishment of a smooth track, or can cause problems in acquistion gate, tracking gate, and turn detection gate selection logic.
Now, back to topic.
Gardeniya-1FUE on export Su-27SK has 9 mode settings, 1-5 are programmed combinations of techniques against specific radar types which 6-9 are more generic techniques.
1 – the program of interference against radars and missiles (base mode)
2, 3, 4 5 – different goal-directed programs of interference, ensuring optimum jamming with specific threat radar indicated by RWR.
6 – Blinking (aircraft in the flight pair);
7 – Low-frequency Doppler noise;
8 – High-frequency noise;
9 – Terrain bounce (in flight at the heights from 50 to 500 m only)
1 was the default mode, when your L006 RWR lit up with a specific threat type (P - Pulse, F4, F104, Harrier and similar, Z - Seawolf, vulcan and similar, H - Hawk (basic and improved) , N - Nike Hercules and Patriot, F - US Teen fighters, C - F-5 and various European radars) you engaged one of the targeted jammng programs (2-5). It they didn't work, you could try more generic measures 6-9 and pray.
For Gardeniya the receiver is in one wingtop pod, transmitter the other, which prevents use of blinking (except cooperatively with a second aircraft) and completely rules out the cross-eye technique.
The Sorbstiya can be fitted on base Su-27 onward and has steerable transmitters in both wingtip pods. It uses analog signal processing but has cross-eye modes. Not sure if it has been exported.
DRFM may allow even newet techniques I am not yet familiar with.
