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Modernizing EW Range Threat Simulators.

EW range threat simulators have been used in aircrew training for over 50 years to generate RF emissions mimicking those of radar-controlled surface-to-air missile (SAM), anti-aircraft artillery (AAA), early warning, ground-control-interceptor, and airborne-interceptor systems. These threat emitters and their associated analysis systems provide training in the form of realistic cockpit cues and feedback to the aircrew in a reactive threat training environment. They also facilitate the performance of airborne equipment checks by providing an indication of operational readiness of onboard electronic combat systems.

Modern threat simulators include the enhanced Sierra Research (Buffalo. NY) AN/TPT-TI Unmanned Threat Emitter (UMTE) and the Harris Corp. (Melbourne, FL) AN/MST-TIA Mini-MUTES IMultiple Threat Emitter Simulatorl Modification Program (M3P) system, which uses an existing platform -- the Lockheed Martin (Ft. Worth, TX) ANIMST-T1 (V) Mini-MUTES -- with upgraded software and hardware. Both of these threat simulators are capable of generating single digit (i.e., SA-X) and certain double-digit (i.e., SA-XX) SAM signals, as well as various AAA threats. The USAF is also pursuing an option to equip UMTE and Mini-MUTES with upgraded electronic-countermeasures (ECM) receivers to enable reactive threat engagements and some post-mission ECM analysis. The M3P meanwhile, modernizes the MiniMUTES threat simulator with upgraded transmitters, antennas, computer suite, and related software, but uses the same pedestal from the original Mini-MUTES. M3P improvements add the ability to track fast-moving aircraft, some double-digit threats, an ECM receiver, and state-of-the-art computer systems.

Current Simulator Deficiencies

Most modern threat-simulator systems are capable of generating various double-digit threats, as well as some of the newer AAAs (e.g., 2S6). One important improvement in employing these newer threat simulators is the elimination of the RF "death ray" syndrome. Most older threat simulators rely on range radars, optical trackers, or aircraft identification-friend-or-foe (1FF) systems to locate and track a target aircraft. Realworld SAM and AAA threats use active search and embedded tracking radars. When a penetrating training aircraft descends to hide behind a hill or mountain (i.e., employing terrain masking), the threat simulator continues tracking the IFF system, even though a real threat would have broken lock. This problem of non-reactivity also occurs when an aircraft responds to a simulated threat with active ECM jamming. A real threat radar would break lock or downmode its radar-tracking, based on the effectiveness of the lamming. With a non-reactive threat simulator, aircrews can engage a threat using proper ECM or correct tactics and maneuvers, but the simulated threat maintains track, resulting in negative training for the aircrews. It is essential to close the reactive loop, enabling the threat simulator to react to aircrew tactics and jamming, in a manner similar to the real threat, thus avoiding the "death ray" problem.

Another important consideration in threat-simulator employment is to provide aircrews with meaningful feedback on their actions during a training mission. Aircraft maneuvers designed to provide a zero Doppler-radar profile or to take advantage of the masking effects of local terrain are common defensive tactics. A modern threat simulator needs to be able to recognize these defensive maneuvers -- as well as expendables and active ECM jamming -- and respond with an appropriate downmode in threat radar tracking in a training scenario, it is essential that each of these actions is recognized, responded to, and included in the aircrew debrief. Aircrews need to understand if what they did was effective in defeating the threat, so they can identify which areas they need to work on during the next training mission. Employing a realistic concept of operations for the threat being simulated is an important factor in the training equation. It is better to learn the correct procedures in training than during the opening hours of a conflict against a real and deadly threat.

An alternative to physical threat simulators is the use of virtual threat simulators, an approach called On-Board EW Simulation (OBEWS), which, suggests injecting computer-generated threats into aircraft EW systems to create a simulated threat environment. A deficiency with OBEWS is that it does not exercise the aircraft's EW self-protection system from end-to-end -- from the radar-warning-receiver (RWR) antennas to the related ECM transmission -- to ensure correct functionality. This concept has a place in EW training as technology advances and aircraft become more digital but there will be a need for physical threat simulators for many years to come.

Reversing the EW-Readiness Decline

There has been a general decline in EW readiness in the past ten years due to funding cutbacks and a lack of emphasis on EW in general. This was evident by an increasing incidence of aircraft passing ground checks of EW self-protection systems only to fail in-flight checks.

Up until the early '90s the USAF had the 87th EW Aggressor Squadron (EWAS), at Eglin AFB, FL (originally at Avon Park, FL), which performed recurring EW-readiness checks of operational combat units. EW readiness has gradually declined since the aggressor squadron was deactivated several years ago. The current EW Aggressor Program (EWAP) Combat Shield program, run by the 16th Electronic Warfare Squadron, 53rd Electronic Warfare Group at Eglin AFB, FL, is a reincarnation of the old EWAS evaluation. This program uses ground test equipment and range threat systems to conduct an end-to-end evaluation of aircraft and aircrew EW combat readiness. The ground check verifies function and software load of EW systems. Combat ready units then fly to ranges equipped with a MUTES threat emitter and a Threat Reaction Analysis Indicator System (TRAINS). The air check confirms EW-system operation in a dynamic "shake and bake" flight environment, focusing on operation during unique in-flight stresses that do not occur during g round checks. However, while the air-check program primarily uses a MUTES/TRAINS pair, not all ranges have these, so the Air Force is adding ECM receivers to two of the newer threat simulators on combat-training ranges: M3P and UMTE. The post-mission ECM analysis used to evaluate the effectiveness of airborne lamming systems, however, will be less thorough than the in-depth parametric analysis accomplished by TRAINS, but these ECM receivers will fill a critical shortfall in ensuring the combat effectiveness of ECM systems.

Compounding the EW readiness problem, 40 percent of US combat-training ranges still have no EW threat simulators; these ranges clearly need something to simulate SAMs and AAAs. Due to a cost of over $2 million per threat-simulator pedestal, there is currently insufficient funding to put full-capability threat systems on every combat-training range -- hence, the development of the RWR Low-cost Training Equipment (RWRLTE), the purpose of which is to activate an aircraft's RWR at ranges without full-power threat simulators. The USAF established a RWRLTE procurement target cost of less than $100,000, with a goal of $50,000 per unit. Given this low cost, though. RWRLTE is a compromise in capability and was never intended to provide full-power, high-fidelity threat simulation. Whereas more expensive threat systems have full effective radiated power (ERPI to accurately replicate a SAM or AAA, RWRLTE is much lower in power. When an aircraft is illuminated by RWRLTE, the threat is displayed with certain inherent inac curacies, such as decreased detection range or ambiguous threat identification. RWRs that "display on detect" show the threat signal immediately. Since RWRLTE has lower power relative to the real SAM or AAA, the RWR thinks the threat is farther away than it really is. Consequently, the threat symbol is displayed at a greater range ring than it actually is. As the aircraft flies toward the threat, the threat symbol moves toward the center of the RWR display, across the range rings, much more quickly than it would for a full-power threat. RWRs that "display on threat" measure threat power and calculate range, while display of the threat is based on the kill envelope of that threat. If a threat is detected, but the aircraft is outside of the lethal range of the threat, the threat is not displayed. This could result in negative training for aircrews if RWRLTE were the only threat simulator used in training. Since RWRLTE is not used to replace full-power threats, though, this is not the case. RWRLTE is only used t o activate aircraft RWRs at ranges without full-power threat simulators as an aid in training aircrews to add the RWR to their crosscheck, forcing them to learn and remain proficient at dealing with threats in all phases of flight and to keep aircrews "on their toes."

The MANPADS Threat and Beyond

Within the past 20 years, a significant percentage of aircraft shootdowns have been due to shoulder-launched, infrared/ultraviolet (IR/UV) man-portable air-defense systems (MANPADS) (see Cover Story, JED, April 2001). USAF combat-training ranges, which are equipped with many full-power threats, do a good lob of simulating RF emissions from older radar-guided SAMs and AAA, but they don't provide training against IR/UV MAN PADS threats, other than through the use of Smokey Sams, foot-tall Styrofoam rockets that spew out a highly visible smoke trail to simulate a SAM. However, these do not trigger the IR/UV missile-warning system (MWS) onboard the aircraft. IR-guided SAMs are a deadly threat against which aircrews need to be trained, and as such, they have become a higher training priority. To help meet the MWS-training needs against MANPADS, and to prepare for the next-generation threat-emitter development program, which requires IR/UV threat simulation, the USAF's Range Threat Systems (RTS) System Program Off ice (SPO) researched what was currently available commercially and found there were no fielded. US-built IR/UV threat simulators. The search, however, did uncover a British-built IR/UV threat simulator, already in use in Europe: Mallina. Built by Elettronica UK, it has been tested against a variety of US and NATO aircraft. A Foreign Comparative Test (FCT) of Mallina is already underway at the Polygone range to determine whether Mallina could meet an immediate operational training need. Further testing will take place at Kirtland AFB, NM, and Eglin AFB, FL, later this year. If successful, it could be used as a stand-alone IR/UV threat system, or due to its small size, it could be mounted on, and pointed by current RF threats such as UMTE or Mini MUTES. With Mallina, aircraft on combat-training ranges could then train against RF-guided, as well as IR-guided, threats. Mallina could potentially fill the IR MANPADS requirement for the joint Threat Emitter (JTE), the upcoming next-generation threat system and the n ext step in modernizing combat-training-range threat systems. As the next-generation EW-threat simulator, it will be required to simulate both single- and double-digit RF threat systems (red, blue, and gray) and IR threats, realistic signal ERP and fidelity, and enhanced mobility. One of the main drivers for the JTE is a need for increased reliability, maintainability, and availability. The JTE program is expected to enter R&D in FY02. Also, given tight DOD funding, and likely future foreign military sales, the JTE could potentially be developed in conjunction with foreign nations in a cooperative R&D program, thus sharing R&D costs.

Lt Col Steve Herrlinger, USAF, is the System Program Director for the RTS SPO at the Ogden Air Logistics Center (Hill AFB, UT).
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Author:Herrlinger, Steve
Publication:Journal of Electronic Defense
Geographic Code:1USA
Date:Jun 1, 2001
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