Warsaw Pact / Russian Emitter Locating Systems (2024)

(Images Czech MoD, RuMoD,Topaz, ERA, MiroslavGyűrösi, Vitaliy Kuzmin, Other)

A topic which appears to cropup with monotonous regularity in the overseas press is that of allegedsales or smuggling to nations hostile to the US of former Warsaw Pactequipment "capable of detecting stealth aircraft". These claimsinvariably involve either the Czech designed and built Tesla-PardubiceKRTP-86 Tamara or ERA Vera Emitter Locating Systems, or the Ukrainiandesigned and built Topaz Kolchuga series of Emitter Locating Systems.More than often this equipment is described as 'anti-stealth radar','radar' or 'passive radar', all of which are completely incorrect.

The purpose of this analysis is to provide some technical discussion ofthese equipment types and their basic capabilities.

Both the Tamara/Vera series, their predecessor the Ramona, and theKolchuga are passive Electronic Support Measures (ESM) systems built toprovide an Emitter Locating System (ELS) capability against airbornetargets emitting radio frequency signals. In this sense they arefunctional analogues of US, French, Israeli and other types ofequipment designed to collect, identify, track and locate RF signalsemitted by airborne targets.

These systems were developed during the last two decades of the ColdWar to bolster Warsaw Pact air defence capabilities in the high densityEuropean Theatre, where it was expected that the US would heavily jamall surveillance, acquisition and engagement radars used in theIntegrated Air Defence System (IADS). The intent behind these passivesensors was to provide a capability to passively detect, locate andtrack US and NATO aircraft using their RF emissions, to cue other IADSelements to an engagement.

The Czechs made the most progress in this area, developing the Ramonaand Tamara systems using the quite sophisticated DTOA (Time DifferenceOf Arrival) technique, one which did not become widely used in WesternELS equipment until much later.

The Kolchuga, Vega/Orion and Avtobaza are more conventional DirectionFinding(DF) systems, with two or more stations they use multiplebearing measurements to fix the target emitter.

The widely propagated public claims that DTOAEmitter Locating Systems are 'passive anti-stealth radars' isdifficult to fathom. All DTOA ELS systems are most effective atdetecting and tracking omnidirectional emitters. For the DTOA ELS tofunction, at least three of the widely spaced antenna/receiver systemsmust detect the very same emission from the target. This is why theWarsaw Pact's Ramona/Tamara family of DTOA systems was used primarilyto track IFF, SSR, VOR/DME, Tacan, JTIDS/Link-16 and other omniemissionsources fromNATO aircraft. A narrow and low sidelobe pencil beam emission from anX/Ku-band radar is even under the most favourable geometricalconditions not going to concurrently illuminate three or more DTOA ELSstations,spaced tens of miles apart, so the DTOA system cannotperform its geolocating function. With low gain antennas needed toproperly cover the required angular extent, the notion that DTOAsystems can lock on to and track sidelobes from X/Ku-band AESAs issimply not supportable from a basic radio physics perspective. The onlypossible scenario in which such a DTOA ELS could track a VLO aircraftis where the aircraft is transmitting via an omni antenna JTIDS/Link-16terminal while penetrating hostile airspace. This is so unlikely thatit cannot be considered seriously.

The only other possible scenario which might be contemplated by thosearguing 'anti-stealth' capabilities for DTOA or DF ELS equipment istheir use as the receiver component in a multi-static radar system,which assumes the volume of airspace in which the VLO aircraft isoperating is also being floodlit by a very high power pulsed emitter inthe UHF/VHF/L-bands. The difficulty then confronted, especially by aDTOA ELS network, is the power-aperture problem. As the angularcoverage of the DTOA ELS stations must be large, this is at the expenseof antenna gain. To achieve a given power-aperture product in themulti-static system, the gain and emitted power at the floodlightingemitter end of the system must be exceptionally large, to compensatefor thelow gain of the receiver components.

Claims that conventional DF systems like the Kolchuga can readilydetect and track VLO aircraft also defy analysis. While they havehigher gain antennas compared to the DTOA ELS designs, they areconfronting the probability of intercept problem against a very lowsidelobe AESA, which is power managed, and highly frequency agile. Theycan only detect and track the emitter if the station is sitting insidethe mainlobe of the AESA, and pointing at it when it is emitting. Theonly scenario where this is feasible is if three or more such DFsystems are closely clustered around the target to be attacked, and allare pointed along the threat axis. Were this true, the DF systems thenconfront a geometrical dilution of precision (GDOP) problem, which willseverely impair range accuracy. The claimed use of DTOA techniques inthe Kolchuga is unlikely to correct this problem due to the very shortDTOA baseline.

The claim that DTOA or conventional DF Emitter Locating Systems providea useful capability against VLO aircraft is simply not credible. Itscontinuing popularity appears to fit in the same category as claimsthat the B-2A's stealth paint washes off in the rain.

USDoDBandAllocationChart

The Topaz Kolchuga is a longrange direction finding Electronic Support Measures receiver system,which if networked can provide the functions of an Emitter LocatingSystem using triangulation and DTOA techniques. The design is claimedto have beennominated for a State Science and Engineering Prize. It was developedduring the 1990s by a consortium including the Special Radio DeviceDesign Bureau public holding company, the Topaz holding company,the Donetsk National Technical University, the Ukrspetsexport statecompany, and the Investment and Technologies Company.

Claimed band coverage extents from 130 MHz (VHF) up to the X/Ku-bands.Claimed sensitivity is -110dBW to - 155 dBW. Track capability isclaimed to be 32 concurrent targets.

The Kolchuga is also claimed to combine DF techniques with DTOAtechniques. The latter will be limited in angular extent to targetswhich fall into the mainlobes of the respective antenna components forthe band in question.

The sale of four systems to the PRC has been reported. There is ongoingspeculation that the system has been supplied to Iran but no validationto date.

Kolchugaondisplayat MAKS 2009. Below, note the revised operator station (©2009VitaliyV.Kuzmin).

Tesla-PardubiceKRTP-81/81M Ramona / SoftBall EmitterLocating System

SemimobileRamona/SoftBallELS variant of the DDR NVAat Gatow AFB (Images © Miroslav Gyűrösi). Additional image [1].

The Ramona was deployed firstin 1979, as a replacement for the PRP-1 Kopac DTOA ELS which wasdeveloped duringthe 1960s, and retired in the late 1990s. It was superceded inproduction by the mobile KRTP-86 Tamara. The Ramona system was built ina semimobile configuration, either on a ground based platform or 25metre tethered lattice mast. The mast mounted variant weighed in total160 tonnes, and was carried by no less than thirteen Tatra 138/148 10tonne 6x6 trucks. The spherical radome housed the receivers anddatalink transceivers required to operate three or more stations.Deployment of the system on site takes 12 hours.

Band coverage was 1 to 8 GHz, with the primary application in locatingand tracking airborne IFF/SSR transponders and TACAN installations.Twenty targets could be tracked concurrently.

The Ramona was regarded to be complicated and troublesome to deploy,factors which strongly influenced the design of the subsequent Tamara.Seventeen baseline KRTP-81 systems were built, 14 exported to theSoviet Union, 1 to the DDR, 1 to Syria, and 1 deployed by the CSLA.Fifteen improved KRTP-81M systems were built, the Soviets buying 10,Syria 3 and the CSLA deploying 2 systems.

Tesla-PardubiceKRTP-86/91 Tamara / TrashCan Emitter Locating Systems

The KRTP-84 Tamara was anevolution of the Ramona, designed with high mobility and rapiddeployment as a priority. Testing of prototypes began in 1983, followedby state trials and certification in 1987. A single system is carriedby eight Tatra 815 8x8 trucks (Equivalent to the MAZ-543), comprisingthree RS-AJ/M receiver systems with telescoping masts, and a mix ofRS-KB hardware containers, RS-KM signal processing equipment containerand a ZZP-5 command van. The mast mounted RS-AJ/M can elevate to 8.5,12.5 or 25 metres AGL and can operate at wind strengths below 60 knots,with a structural limit of 100 knots. The cylindrical antenna radomehouses the receiver equipment and datalink transceivers for networkingthe stations. In a typical deployment the receivers are stationed atdistances of 5 to 20 NMI.

Cited band coverage is 820 MHz to 18 GHz. Design objectives includedthe tracking of the F-15 at 200 NMI and F-16 at 215 NMI, with the citedrange limit being 240 NMI and limited primarily by the curvature of theearth. Russian sources claim that 72 targets can be tracked within a100° angular sector, these including emitting JTIDS/Link-16 terminals.In 1991 the baseline KRTP-86 was superceded in production by improvedthe KRTP-91 Tamara-M.

Russian sources claim that 23 Tamara and Tamara M systems were builtbefore production switched to the Vera series. Of these, theUSSR/Russia acquired 15 Tamara systems and 4 Tamara-M systems, the CSLA4 Tamara M systems, the GDR NVA one Tamara system, with claims that theUS acquired two systems via Oman.

ERA Vera E EmitterLocatingSystem. The Vera E equipment displayed to date has been installed ontrailers rather than the robust truck mounted mast system of the Tamaraseries (Image © Miroslav Gyűrösi).

The post Cold War Vera systems are improved derivatives of the Tamara,and have not proven particularly successful in the market, in a largepart due to the fact that the clients most interested in the productare not part of the Western alliance. China was granted export licencesin 2004 for six Vera-E systems, which were revoked after pressure wasbrought to bear by the US State Department. There are reports thatMalaysia, Vietnam, Pakistan and Egypt were interested in acquiring thesystem. The Czech Army has acquired one system, the US DoD one system,and the Estonians one system.

RAMET / VTÚOSDD StaniceDalekého Dosahu (Long Range ESMStation)

SDD long range ESM of the 531stPassive Surveillance Systems Battalion of the Czech Army (CzechArmy image).

DeployedSDD long range ESM of the 531stPassive Surveillance Systems Battalion of the Czech Army(CzechArmy image).

StowedSDDlongrange ESM of the 531stPassive Surveillance Systems Battalion of the Czech Army (CzechArmy image).

The Avtobaza ELINT system isdesigned to detect airborne side-looking radars, air-togroundfire-control radars and low-altitude flight control radars, as well asto provide intelligence data for the 1L125M APUR.

Composition

• equipment vehicle based on the Ural-43203 chassis with theK1.4320 van
• ED2x16-T230P-1VAS electric power generator in the K1.4320van on the Ural 4310 chassis

The ELINT system displays on the TV screen acquired targets with dataon their direction finding, angular coordinates (azimuth andelevation), radiation signal parameters (carrier frequency, duration,pulse repetition frequency) and radar type classification (sidelooking,fire control, low-altitude flight control radar). The APUR automatedjamming control system is fed with target data (frequency band numberaccording to frequency assignment of jamming systems, type of emittingradars and their angular coordinates) via cable at a range of up to 100metres.

CETC DWL002Passive Detection System

The strategic significance of the DWL002is that it is the first DTOA technology ELS which has been designedfrom the outset with the intention of providing robust heightfindingcapability when passively tracking an emitting target. The ability togenerate near-realtime or soft realtime 3D target tracks would beespecially valuable in supporting SAM systems like the S-300PMU2 orHQ-9, as this could be employed to cue the SAM engagement radar veryprecisely to the inbound target. Should the accuracy of the ELS besufficiently high, it could be employed to generate post-launchmidcourse tracking corrections for outbound SAMs.

The CETC brochure describes the system thus:

“DWL002 Passive Detection System, also calledaspassiveradar, ismainly used in air-defense or seashore monitoring to perform thedetection to perform the detection and location to airborne, shipborneor landbased emitters in complex electromagnetic environment anddisplay the target flight path in real time. The system can alsooperate together with active detection system to form a mutualsupplementary surveillance network.

Typical configuration of DVL002 Passive Detection 'system is composedof three reconnaissance stations. One of them serves as master stationand the other two as slave stations. The system can be expandable tofour station configuration with perfect performance of full spatialcoverage and altitude information of air target. Each station iscarried by an individual vehicle.

Main Functions:
* Realtime & Accurate Location and Tracking
* Signal Analysis and Identification
* Long Range Detection and Early Warning

Main Features:
* Passive
* Real Time
* Very Good Mobility

DWL002 Passive Detection System is a three station configuration(expandable to four station configuration). Each station. includingantenna and power generator. is housed and carried by one vehicle.which ensures the good mobility of the system

* Remote Control
* Advanced techniques

Long base line time difference of arrival (TDOA) location techniquecombined with AOA: Wideband digitized receiver technique; Multilevelcorrelation processing technique with good flight track processingresult: Automatic set up. Chassis leveling techniques and automaticnorth calibration technique to ensure fast deployment and flexibleoperation.”

DLW002 antenna arrangement.

DLW002 CONOPS diagram.

DLW002 console display of target track.

CETC YLC-20Emitter Locating System

The CETC YLC-20 isa DTOA/DF system modelled on the Tamara M (via IASC)

Stated band coverage is 380 MHzto 12GHz. Deployment time is claimed to be 1hr, with all system components on 8x8 or 6x6 trucks. At the time ofwriting no good quality imagery of production equipment was availablethrough opensources. This limits current assessments of the system's capabilities.It is likely that DTOA techniques are used for target acquisition andcoarse tracking, and DF techniques used for precision tracking, usingDTOA derived coordinates to cue an interferometric DF antenna.Avaliable material does not state whether a heightfinding capability isprovided, if so this would likely be performed using interferometrictechniques with the DF subsystem. Once better quality imagery of theantenna arrangement becomes available, a more precise definition ofcapabilities and limitations will be possible.

It is likely that much of the YLC-20 design is based ondocumentation acquired during the abortive attempt to procure six CzechVera E DTOA ELS systems. The YLC-20 was first disclosed in 2006.

We have yet to see hard evidence that thePLA is integrating the YLC-20 or Kolchuga M with its S-300PMU/PMU1/PMU2SAM batteries. That is however not a technically difficult task toperform and given recent Chinese writings on the use of VHF radar toprovide midcourse guidance for SAMs, something we can be certain thePLA is planning. The principal risk which arises is that emissions fromany network antennas on combat aircraft which can be detected by morethan two DTOA or DTOA/DF ELS would permit passive tracking and providecoordinate data of sufficient accuracy to effect a SAM shot - or vectora fighter (Author).

DTOA systems make use of threeor four widely displaced receiver stations which employ a synchronisedhigh precision clock. All received signals, such as radar pulse trains,IFF emissions, network or datalink packets, etc are identified, sorted,and timestamped, and the collected data relayed to a central processingsite, such as a van. What a TDOA system exploits is the fact that thegeographical location of any emitter which produces a specificdifference in time of arrival to a pair of receivers will fall along ahyperbolic curve termed an "iso-chrone" (curve of like time).

With two receivers the observer knows only that the location of theemitter falls somewhere along a curve. With three or more receivers,the observer knows the emitter falls somewhere along several curves.The points where these intersect is where the emitter can be found.