Writing something about the french Electroniques Counter Mesures is not an easy task .
A entire book would probably not be enough , so I am only going to try to show few interesting things .
France started to really work on ECMs in the begining of the 60s (in 1964 to be precise) . Before that , , the researchs were marginals .
Until these dates, no specific equipment of EW existed on the aircraft of the units concerned. EW was limited, for the crews, to apply procedures of escape from frequency in the event of radio operator jamming. That does not mean that up to that point, EW was not a subject of concern for the air force. But for this one, in Europe in any case, in the context of the cold war, it was a question much more of raising of the indices of alarm, by listenings radio-radar starting from stations on the ground, that to ensure, by specific equipment of countermeasures, penetration of the planes of attack.
From 1959 , the Russians started to field systems like the SA-2 and SA-3 (1963) . From there , Russia fielded a new system every 2 years (SA-4 to SA-12) .
It should finally be recalled that the air force created its first three stations of listening radio-radar ground respectively in 1954 in Achern, 1958 in Berlin and 1962 in Goslar. The device was supplemented later on in 1967 and 1968 by the creation of the electronic Squadrons ground (EES) of Bad Lauterberg and Fürth im Walde, on the Czech border.
1964 is the year when the first squadron of Mirage IV is created, then single component of the strategic Nuclear force (FNS). It is a question of ensuring the penetration high-altitude of these aircraft above territories strongly defended by interceptors and also by ground-to-air missiles. SA 2 and SA 3 are already deployed in the USSR, while waiting for the startup of SA 4 in 1967, and SA 6 in 1970: from where the equipment of these aircraft in electronic means of countermeasures (ECM) of self-defence, with knowing primarily of the jammers bandages X against interceptors (Agacette) and of the jammers of radars of control of shooting of ground-to-air missiles SA 3 and SA 6 (Mygale and Agasol). These systems were improved throughout the life of Mirage IV, and others were added.
Around 1972 , the AdlA looked carefully at what hapened in Vietnam .
In 1967, the United States lost 326 aircraft above North-Vietnam, including 85% because of ground-to-air defense: from where an upheaval in the modes of attack and the equipment of the aircraft . The density of anti-aircraft artillery (the first ZSU with radar of fire control system appeared in 1965) resulted in prohibiting the penetrations at less than 4.000 feet .
The USA then started to use chaffs and systems like the EB66 / B52 /EA6A et B . It is about at the same time than wildweasel Units became usefull , with the AGM-45 “Shrike” anti-radar missile .
There was also a change of tactic: with isolated patrols succeeded of the complex devices where, for a plane of attack, one counted three or four aircraft of accompaniment, of which planes specialized in offensive EW . In 1972, above North-Vietnam, American losses were ten times lower than those of 1967.
The first true French ECM systems were fitted on the Mirage IV :
– Agacette jammer to counter the Russian fighter radars (8 to 10 GHz)
– Agasol jammer to counter the Russian SAMs
– BOZ chaff dispenser
Then later on :
– Phimat Pod
– Thomson-CSF SERVAL
– Alkan F1A shaff/flares dispenser , then BOZ 103
– Thalès BARAX-NG pod
Other systems were later fited on the Jaguar .
In fact , France created a “Company” called Guerrelec very similar to the US “Old Crows” , in charge of developing new breeds of electronic warfare components . Very little is known about Guerrelec , even today , because everything is still classified .
The first offensive jammers dated from 1976-77 , the early systems had a good reputation but lacked the needed power to truely “blanket” the battlefield .
Jammers like the BARAX-NG and Barracuda were fitted in 1980 on various aircraft and participated at “Red Flag” and “Green Flag” and were praised by the USAF .
From there on , various other systems were tried during the Nato MACE exercises . In the late 80s , our ECMs became famous within Nato and France was the Leader in MACE (and still is) .
It is about at this time than the French found out that analog systems participated for about 10% of the survivability of an aircraft while 80% of the survivability was archieved through offensive jamming . Better systems were needed and the digital approach was the way to go .
We have to understand that ECM and offensive jamming must fullfil 2 goals :
– jam the adverse radars
– not to jam friendly radars
To archive this , one must know every system around (!) , then how to “classify” if the radar is friendly or not . To this extent , huge databases are needed .
So it must to some extent cumulate the self capacitance of each one of these sources. It results from it from the requirements from performances of several orders of magnitude, meaning 10,100 or 1.000 times higher than those which can require each taken source separately.
The first example is that of the waveband hertzian, or wavelength an electronic system of war must cover. Today a very great number of the types of radars, occupying all the spectrum of the frequencies, from the waves métriques or decimetre, for the large radars of remote detection, to the millimetre-length waves, for the small radars of final guidance of missiles.
(Metric wavelength are very useful against stealth targets , but this is another matter and will be covered later on)
To make it short , an ECM suite must be capable to work 10 to 100 times faster than the system it is trying to jam .
Contrary to the radars, which know what they are going to receive – what they have emitted – and which consequently can select very early what interests them, in placing a window adapted exactly to the emitted signal, them systems of electronic war, largely open on the world outside, receive at a moment given all kinds of signals, of which it is necessary to find what is interesting. It is necessary to sort these signals, to separate them from/to each other. It is thus necessary to have the equivalent of tens of thousands of small receivers granted each one to a given frequency, to select possible emission at this frequency . If one wants to know where the emission comes from , it is still necessary to multiply the number of these receivers, to look at simultaneously in various directions.
Basicaly , one need extremely sensitive receivers working simultaneously in multibands : 1st problem
To archieve this , one must have a really fast computing power in the order of 1 μ second for a resolution of 1 MHz . This is why the technology could only be archievable in the early 90s and not before .
Then , one must translate the received signals into binary form and analyse them to find out a way to send them back in various forms to jam the adverse radar : 2nd problem
We are talking about Gigabytes of data who have to be computed very quickly (in the order of tenth or milli seconds) .
To archieve it , we need to “cheat” Physics !
How ?
France asked to her best physiciens (like the polytechniques institute , the “X” people) to find ways . These poeple came out with 2 different techniques :
– 1) Asymptotic calculus using optical physics which lead to special Bragg cells
– 2) a special calculus called (in french) calcul des elements finis
These studies lead directly to SPECTRA .
Soon , our physiciens found out that these equations could also be used to counter stealth . Here , I don ‘t have much data because it is highly classified but from what I can understand , the very few returns of EM radiations when hitting a stealth object can be computed . But this is a different story …
A new breed of “Carcinotron” (backward wave oscillator) have seen the light , first employed in the ICMS ECM suite on M2000 , later on the technique was implemented on Bragg Cells and MMICs based on GaAs (Gallium Arsenide) . This technology is using hyperfrequency transistors and algorythms capable to sort out multi frequencies , to amplify them and to change the frequencies on the fly .
Since , GaN (Gallium Nitride) has replaced the GaAs and brings even more power and flexibility . SPECTRA F3 will use the technique to make active cancellation possible .
Of course , the jammer must use AESA technology for the trick to work .
France is using special Bragg Cells (called dispositifs à ondes acoustiques de surface) to translate radio waves into acoustic and optical waves propagated on a cristal surface using transductors . This technology allows the received radio waves to be manipulated at will .
It is very complicated but it does marvels !
(More later , I am tired)
Cheers .
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May 5, 2010 at 9:56 pm