Navigation Simulation Options for Ground Testing of Installed Systems

P. Cook, J. McCune

Abstract:	Today´s military aircraft are increasingly dependent on the use of advanced technology weapons systems sensor systems to satisfy the growing complexities and diverse roles of multi-mission air warfare. Consequently, installed weapons systems sensor testing requires simultaneous, and correlated, ground-based T&E on a variety of installed multi-spectrum sensor configurations with integrated avionics systems and subsystems. Installed systems T&E cost effectively optimize the use of scarce flight testing resources while also satisfying increasingly sophisticated tests. It is now an accepted and highly costeffective practice to first conduct rigorous ground testing and evaluation of the installed/integrated sensors´ performance, and interaction to determine their readiness for range and/or flight-testing. In particular, interference in navigation systems creates a safety-of-life issue even under the best of conditions. Also, loss of communications or Radar systems during flight testing could be disastrous. One method of risk reduction is the ground testing of fully installed systems before the first flight. At NAVAIR´s Integrated Battlespace Simulation and Test (IBST) Department´s Air Combat Environment Test and Evaluation Facility (ACETEF), engineers create an environment on the ground to simulate flight through a noisy environment. At ACETEF, there are three options for integrated navigation during ground testing all of which are compatible with the Joint Integrated Mission Model (JIMM). JIMM can control a number of simulators and stimulators for integrated testing. For simple static scenarios, a live feed signal can be reradiated to the system under test. For testing that requires a location other than the test facility or dynamic testing either simulation, stimulation, or a combination of the two. In order to simulate GPS and INS, the navigation system is disengaged and a program used to directly input navigation data onto the data bus based on the scenario running in JIMM. To stimulate the navigation system, a GPS and INS simulator is used for dynamic inputs simulating the constellation visible at any time or place. If the navigation system is not under test, but other systems need GPS RF input for timing, simulation and stimulation is combined. IBST´s large anechoic chamber allows engineers to place large aircraft, up to the size of a Boeing 707, or two tactical aircraft in a secure environment in which to radiate. Adjacent to the large anechoic chamber is the Operation Control Center (OCC) which together with the chamber can be controlled for security purposes. Within the OCC, testing is controlled and monitored. A number of stimulators are controlled independently or in a coherent scenario using JIMM. Unlike in-flight testing, scenarios are repeatable to verify results and give applesto- apples comparisons. In addition to the large anechoic chamber, IBST has another smaller anechoic chamber that is 100´ x 60´ x 40´ allowing testing of installed systems in smaller vehicles. The smaller chamber easily accommodates a single tactical aircraft, helicopter, or truck. JIMM and all of the command and control equipment used in the large chamber are available for use in the smaller chamber. If an anechoic chamber is not needed, testing is performed in either our shielded hangar or shielded labs, in the case of small craft such as UAVs or bench testing of individual systems or subsystems. There is also the option of performing open air testing in front of the shielded hangar. Obviously, as one moves into less shielded environments certain restrictions apply to the available signals. But in all cases, prescripted coherent scenarios or stand alone simulation control can be used. In addition to the navigation options available the customer may choose from a number of signals depending on the specifics of the test requirements. • Realistic open-loop RF environment stimulation to electronic warfare systems o Radar warning receivers o Electronic support measures o Defensive electronic countermeasures o Standoff and support jammers o Communications intercept • Radar o Open-loop RF Radar stimulation o Coherent free-space target returns o Select airborne radars only • Communication o Inmarsat o Link – 16 o Link – 4 o Link – 11 o TRAP o TIBS o TADIXS-B o OTCIXS • Civilian background signals o Radio o TV o personal voice communications • Identify friend or foe (IFF) o Modes 1, 2, 3, 4, C and S o Upgradable to Mode 5 With these tools, it is possible to create a realistic environment in which to simulate flight of the system under test. Given this ability it is possible to test even systems that require an aircraft to be off the ground to activate. Many options can be tested in a fair and unbiased setting of exact repetition of signals. Most importantly this can all be done in an environment where loss of navigation or other systems will not constitute a safety-of-life condition. This allows intentional removal of navigation signals to determine reacquisition in undesirable conditions and threshold of signal degradation and loss in a fully integrated system without any danger.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	2248 - 2250
Cite this article:	Cook, P., McCune, J., "Navigation Simulation Options for Ground Testing of Installed Systems," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 2248-2250.
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