Counter-stealth technology flourishes in eastern Europe by Chris Pocock European companies, especially in the East, are continuing to refine passive ground-based technologies with the potential to detect stealth aircraft. The best known of these is the detection and correlation of emissions from aircraft– such as from radars, radar altimeters and other navigation devices–using ESM/ ELINT techniques, sometimes known as passive emitter tracking (PET). Various techniques are used to calculate the position of the target, such as triangulation, interferometry and TDOA
(time difference of arrival). In recent years, detection has become possible by capturing and analyzing the signal fluctuations caused by an aircraft as it flies through the fields of civilian radio, television and mobile phone transmitters. The latter technique uses Doppler-shift processing together with bi-static range and angle-ofarrival measurements. It is usually known as passive coherent location (PCL), but is sometimes referred to as “passive radar.” The accuracy of both PET and PCL systems has improved progressively thanks to
PHOTOS: Myroslav Gyurosi
The Ramona and follow-on Tamara passive detection systems were deployed by Warsaw Pact countries on mobile vehicles.
Gunica is a truck-mounted system designed by Polish company PIT.
Silent Guard is a van-based PCL system from ERA, with self-contained operator workstation.
the increase in processing power. Czech company ERA has inherited and refined the PET and TDOA technology that was developed in the former Czechoslovakia and exported from there to East Germany, North Korea, Syria and the Soviet Union. The PRP-1 Kopac system of 1963 was followed in turn by the KRTP-81 Ramona in 1979 and the KRTP-86 Tamara in 1987 (later upgraded to KRTP-91 version). In 2009, ERA created the VERA-NG passive emitter tracking system with a lighter, more compact antenna unit. Last May, the NATO Communication and Information Agency (NCIA) signed a contract with ERA for two VERA-NG mobile systems, after previous demonstrations during NATO exercises. ERA’s latest PCL technology demonstrator is called Silent Guard. This design exploits commercial terrestrial radio broadcasting signals in the 88- to 108-MHz band (up to eight FM channels
per sensor). The system has 360-degree coverage in azimuth. ERA claims a range of up to 150 km depending on antenna type and target RCS. Silent Guard operates in a completely covert mode, and has a redundant architecture. The system has very low power consumption because there are no rotating parts in the antenna unit. For this reason, the maintenance cost is also very low.
This is the latest version of the Kolchuga system designed by the Topaz company in Ukraine.
Airbus D&S Refines Passive Radar, Explores Civil Use
Airbus D&S
At the recent ILA Berlin Airshow, Airbus Defence and you can’t jam it,” he said. “There’s no turning & Space reported progress with the passive radar radar antenna, so we spend 100 percent time-on[alternatively, passive coherent location (PCL)] sys- target, with an update rate of 0.5 seconds instead of tem that predecessor company Cassidian had been six seconds,” he continued. “Moreover, there is no developing since 2006. Frank Bernhardt, proj- need to secure frequency allocation and approval ect manager, said that the company from governments,” he added. has “worked closely” with two armed The UK CAA is interested in the forces on tests of the system. One of potential for passive radar to release them is Germany. Airbus D&S has also precious bandwidth for other uses, gained a study contract with the UK Bernhardt said. The new contract Civil Aviation Authority to explore the will also explore how the system ATC applications of passive radar. could be placed in built-up areas Bernhardt reported that a second without creating emissions, unlike a sensor van was added to the system radar system. last year, thus providing more ellipAccording to Airbus D&S, sevsoids and improving accuracy. The eral cost-effective passive-radar sensystem has been adapted to work with sors using a number of emitters could DAB+ signals, with DVB-T2 to come. broaden the basis for detection of air“I believe we are still the only ones to craft approaching an airport. Plachave fused three bands,” he added. The ing several such sensors intelligently The Airbus D&S passive system can process eight FM transmit- radar system is deployed could also eliminate the problem of ters, plus one each of DAB+ and DVB-T. on one or more vans. confusing echoes and interference Airbus D&S claims a detection range of Signal processing is from the increasing number of wind done onboard, and the up to 200 km (FM) for larger aircraft, farms that are afflicting conventional combined 3-D air picture and an accuracy of 10 m (DAB/DVB-T). is then transmitted by ATC radars, the company added. The recent test used two light aircraft ASTERIX data link. Interestingly, since the system needs and a Learjet 35 as targets. no cooperation from aircraft tranThe attractions of passive radar are many, sponders, it might have provided clues to the fate of according to Bernhardt. “You don’t know where it Malaysia Airlines Flight MH370, had it been deployed is, you don’t know how many [detectors] there are in the relevant area. – C.P.
72 Farnborough Airshow News • July 14, 2014 • www.ainonline.com
Czech company ERA has been promoting the benefits of its VERA-NG mobile passive-emitter tracking system.
Pole Position
Polish company PIT has also developed the work done on both ESM/ ELINT and TDOA systems in that country during the Warsaw Pact era. The company offers the SRS-25S Gunica system, which operates from 0.5 to 18.0 GHz. Also in Poland, The Institute of Electronic Systems of the Warsaw University of Technology in Poland developed and tested a PCL technology demonstrator called PaRaDe (Passive Radar Demonstrator) in 2009-12. The PaRaDe technology demonstrator can do real-time processing of FM signals and offline processing of DVB-T, GSM and Wi-Fi signals. The development team claimed a tracking range of 750 km. PaRaDe uses a three-meter diameter antenna array, which is located on an eight-meter high mast. Another Polish company, Bumar Elektronika, is working on a totally new design for a mobile passive surveillance system, which will combine PCL and TDOA technologies in one chassis. That will be the first system of this kind in the world. One of the best-known passive systems is the Kolchuga, built by Ukrainian company Topaz. It is a long-range mobile system that receives and triangulates ESM/ ELINT data. It can detect and identify pulse and continuous wave emitters from 135 MHz all the way to 18 GHz. Detection range is up to 600 km, and tracking range up to 200 km. In the standard version, three antenna-carrying vehicles are deployed in line, and can cover a 120-degree arc. The newest Kolchuga-3K system adds a fourth vehicle and array to provide 36-degree coverage with a detection range of 450 km. Both versions can simultaneously track up to 200 targets. Turning to emitting radar systems, the former Soviet Union and Warsaw Pact countries also specialized in VHF-band systems, which are more likely to detect stealth aircraft because of their larger wavelength. VHF radar development continues today in the Belarus, the Czech Republic, Poland, Russia and Ukraine, and includes the use of active electronically scanned arrays (AESAs). o