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EW simulators promise accuracy, cost reduction.

EW Simulators Promise Accuracy, Cost Reduction

The US Navy's new Strike Electronic Warfare Simulator (SEWS) program is fast nearing completion at the Naval Weapons Center (NWC), in China Lake, CA. When it begins operations later this year, SEWS will provide an essential tool for evaluating modifications to existing EW systems and furnish guidelines for the development of new ones to be deployed by the fleet.

The program's charter is to support analysis of EW systems and their impact on the strike effectiveness of airborne weapons systems. This will be done through detailed evaluations of customer-supplied EW digital software models in different environments.

Most EW systems are too costly to test fully on real platforms, and cannot be tried out in real-world mission environments. SEWS will test proposed new or modified systems using detailed computer software modeling. This should result in considerable savings in time, money and aircraft compared to relying only on flight tests over test ranges or the kind of system stimulation provided by anechoic chambers.

SEWS consists of a software development capability high-speed digital off-the-shelf computers, a control display subsystem, specialized programming and the staff to operate it.

The SEWS equipment is installed in two buildings at NWC: a [1400-ft.sup.2] computer vault and an equally large analysis vault. A third structure houses personnel, and a fourth will contain the SEWS library and software development stations when the system becomes operational in the fall of 1990. All SEWS buildings will be in a highly secure compound. This is necessary to support the multiple levels of security with which the system will operate.

SEWS's computing requirements are still undetermined, but they will not be minor. Version 1.0 has been done with a Cyber 930 at NWC, but the sites where it might be used typically have VAXs. Unless users are willing to wait weeks for an analysis, the future, complex versions of SEWS will not run on a VAX. SEWS will need the power level of a Cray; however, other options such as parallel processing versus vector processing are presently under consideration. The NWC team has not yet settled on the ultimate configuration.


SEWS software will provide the following capabilities: interactive scenario generation and the evolution of complex scenarios, EW models, weapon effect models to support threat suppression, simultaneous model operation, data journaling and data analysis. The system is designed to be expandable and to incorporate new and updated models easily. The models will be valid, predictable and repeatable, and will enable users to take advantage of a quick turnaround time for data reduction.

A man-in-the-loop capability will eventually be available to evaluate operational techniques used with EW systems. For example, a pilot will be able to maneuver in conjuction with dispensing expendables.

The SEWS system is menudriven. The user can determine a scenario and save the script for future runs or changes. To create a scenario, the operator selects a platform, such as an attack aircraft, and configures it with equipment such as a jammer, chaff, flares, etc. He then sets the aircraft's position at an assigned altitude, speed and heading, giving it a name for computer identification.

The operator then chooses other platforms, such as Soviet ships, and gives them surface-to-air missile systems, early warning radars, etc. This sample scenario is now ready to go.

As SEWS Program Manager Roy Wescott expressed it, "We're putting together a system that will allow analysis to be done that is not available now - there's no facility capable of doing it. This is the evaluation of the strike effectiveness of an EW system in a many-on-many environment down to pulse-level detail."

SEWS modeling software is being developed in-house with contractor support. If NWC requires a particular model, it will look to a contractor with experience in that particular subsystem. If the vendor is already under contract, NWC will go there for contractor support.


The planned budget for the SEWS program runs at about $3 million per year. But the savings in testing of systems and, as a result of this testing, the possibility that some of them may not be deployed if it is determined they are not needed or would not work as expected, is not as easily factored.

One way of measuring the value of SEWS is by comparing it to another method of testing. For example, NWC's Electronic Warfare Threat Environment Simulation (EWTES) facility is popularly know as "Echo Range." It is the only Navy facility designed to provide a realistic EW and defense-suppression environment for the RDT&E of airborne ECM weapons and tactics against simulated EW sites and surface-to-air weapon systems.

On the average, it costs $20,000 to send an A-6E flight against EWTES. It will only cost a few hundred dollars to fly the mission in SEWS.

But while the savings this capability will provide are considerable, the program's true value lies in being able to do things which cannot be done on live ranges. One of the disadvantages of facilities like Echo Range is that they are set up for a limited number of threat emitters compared to what would actually be encountered were a real mission to be flown into hostile territory. SEWS will eventually make it possible to construct an entire digital power projection threat environment and fly against it with several aircraft. In the real world it is physically and economically infeasible to bring a fleet of 50 aircraft into Echo Range - this is only one of several advantages of a many-on-many simulator like SEWS.

Another benefit is that SEWS will provide a nonobservable test environment to analyze classified test missions and systems. At present tests of this kind cannot be carried out anywhere in the open, due to the possibility of satellite or other forms of detection. SEWS will allow the Navy to carry out these and other tests it cannot do now at Echo Range or with hardware-in-the-loop type simulators.


When considering any systems

When considering any system of this type, one of the first questions that comes to mind is "How accurate are the simulations it provides?" Simulation accuracy will be a function of the precision of intelligence information describing the threats, and the programmer's ability to integrate them. The software will reflect whatever information can be obtained or deduced about the hostile system.

For example, the first system SEWS will test is scheduled to be the AN/ALE-47 expendable dispenser. It will undergo live testing at NWC facilities in the early part of FY 1991. The contractor (Tracor) is preparing the digital model. SEWS tests will be conducted in conjunction with planned live tests.

The AN/ALE-47 will be tested using Version 1.0 of SEWS. The following version will be specifically aimed at the A-12, to evaluate which EW options it should or should not have over its built-in baseline capability. In each case it is the responsibility of the user agency to provide the digital models to be tested by the system. However, the agency may, as with the AN/ALE-47, hire the system contractor to produce the digital model of the system he is building.

There will also be models of the GEN-X expendable decoy. This will make it possible to fly a high number of runs, "expending" large quantities of GEN-Xs without depleting the inventory. This not only saves money, but allows testing at a magnitude otherwise impossible. Even common flares used at the rate the Navy envisions for SEWS tests would result in a very expensive undertaking.

All these models will be used with NWC's own digital representations of US EW systems housed on the platform. Interfaces will simulate the aircraft's other avionics.

The latter is important because many EW systems need to "know" where the aircraft is, its attitude, whether it is turning, etc. Therefore, SEWS developers must simulate the platform's navigation system and feed that kind of data into the model of the EW system under test. Thus, SEWS not only provides the threat environment, but the rest of the blue environment as well.

The system's level of detail will eventually allow pulse-to-pulse emulation of the entire ether - multispectral and not just RF. When a radar's model is properly developed, its actual performance degradation under jamming will be displayed.

Current accuracy validation is for threats that have been measured already at such places as Echo Range. Other validations will be done against simulators that put actual hardware in the loop for one-on-one encounters between an EW system and the particular threat. In other cases, validation can only be done against an analyst's estimates of performance.

Ultimately, accuracy figures of merit will be derived (each from real-world validations) for the system scenarios. NWC experts are the first to admit, however, there will never be 100% accuracy. As Wescott defined it, "Not even on Echo Range is it ever possible to repeat the same real-world mission with precisely the same results."

The system will be used by engineering analysts and others trying to evaluate EW techniques and their impact on the strike effectiveness of particular platforms such as A-12 and F-18 aircraft. There is some thought of using it someday to support operational evaluation of EW systems. This would be particularly applicable to cases where it is not feasible to fly a number of aircraft against a real threat.


The next step for SEWS will be man-in-the-loop simulations. This does not mean there will be an A-12 cockpit with an airplane driver working it like a weapons system trainer. What it does mean is that users will be able to program the aricraft's destination and enter all the mission planning data that an air crew might put into the system - what kinds of targets, what frequencies may be encountered, etc. Eventually all this will be a part of the scenario generation.

As Wescott put it, "There will be some rule-based kinds of things derived from talking to air crews, such as `When I get to a point where I'm radiated by a particular radar I am going to dispense chaff and turn left.' We'll incorporate this sort of data into the software so when the encounter occurs and our system calculates that the radar would now see the aircraft - or its RWR would react to the radar - it'll know the pilot would carry out a particular maneuver or activate certain systems, and have this take place in the simulation."

Wescott added that this does not require someone actually getting in the loop and doing it. "We're not aiming for a real-time man-in-the-loop condition. We want to determine what the strike effectiveness of an aircraft with a certain system is versus perhaps a competing system or new system of that kind. SEWS is an evaluation and analysis resource, not a training tool."

When the system is up and running, will the number of test missions decrease? Not according to the NWC team. The purpose of SEWS is to allow more thorough, accurate analysis with the same flight hours. The simulator will expand analysis capability, validated against the live tests. Live flights will remain a necessity.


The Air Force has an EW simulation program similar to SEWS: the Electronic Combat Digital Evaluation System (ECDES). It is under development at Wright-Patterson AFB's Electronic Combat Office, Test and Analysis Directorate. It operates under Chief of Division Lt Col Glenn Harris, who has nursed ECDES since 1984, when it was a small research project. This is a Wright-Patterson development, using a combination of contractor, laboratory and government team work.

ECDES and SEWS exchange data and protocols, with both programs participating in each other's design reviews. Joint aims are software compatibility and directing development along compatible paths, while avoiding duplication. Similarities between ECDES and SEWS are being identified and used in both programs, enabling them to use the same components.

ECDES's charter is somewhat different from that of SEWS: the Air Force is developing a modeling and simulation system. This software, written in Ada, would go to using locations (laboratories, program offices, authorized contractors) that will evaluate it and build digital models of EC systems. Initially, ECDES will address mostly air-to-air models. There is also some requested surface-to-air modeling support from the Army. As the modeling and simulation system matures, full land, sea and air EC system battlefield simulation will result.

Like SEWS, ECDES is a software system, an architecture that uses modeling data to interact in an environment selected by the operator. In and of itself, it will not be a model. ECDES will be an analysis resource, a systems design tool that will allow the interacting of parameters against known threats or systems. This will enable it to determine how well a new EW system design might operate, based on user-provided models.

Eventually, a network of current ECDES users who will access this resource is expected to develop around the country. By that time, there will be a library of standard digital modeling components incorporated into ECDES, available for users to build additional models. These will interact with others in a realistic EC environment.

According to Tom Smith, ECDES program manager, the system will evolve. "As we go through concept evaluation and into demonstration validation of new EC systems, we will proceed from the fully digital representation of such a system model into a real-time laboratory system like the Integrated Digital Avionics Laboratory [IDAL] here at Wright-Patterson," he explained. Smith added that the IDAL would use the same parametric data as an EC model, but in real time. The data might even be used with cockpit procedures developed for real-time simulations. This would enable IDAL to feed any corrections, updates or errors revealed by their real-time environment, back into the ECDES digital non-real-time system to update the EC model under study.

Similarly, the EC system under development will be evaluated by hybrid simulators and integrated hybrid simulators and integrated test facilities during full-scale development. Continued updates and changes will be reported to the ECDES support facility, where the primary model will be modified to represent the system more accurately.

ECDES is still conceptual, with prototyping taking place. It is beginning its system engineering development phase, which is predominantly software oriented. A prototype of the engineering-level system, usable by some of the DOD evaluation sites, should be ready on or about May. NWC is the planned Navy site, with the Missile and Space Intelligence Center (MSIC) in Huntsville, AL, the planned Army site for joint program participation. Others will come in line as the program evolves.

SEWS and its Air Force counterpart, ECDES, are viewed not only as valuable evaluation tools for EW systems of the 1990s, but also as important resources with which to explore the most effective EW alternatives for meeting threats well into the 21st century.

PHOTO : An example of a SEWs simulation screen.

PHOTO : Strike EW Simulator (SEWS) schedule/status.
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Title Annotation:electronic warfare
Author:Braun, Alexander E.
Publication:Journal of Electronic Defense
Date:Jan 1, 1990
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