Navy

Multi-agent RF propagation simulator

Signal propagation simulator specifically used to determine the performance of a communications system prior to open-air range (OAR) testing

Communications Electronics

Accurately modeling RF communication systems in the lab can better assure optimal functionality in the field.

Currently, in certain types of antenna design fields, the correlation between model and simulations (M&S), hardware-in-the-loop (HITL) testing, and open-air range testing is minimal. Open air test ranges introduce many uncontrolled variables that not only affect the performance of an RF communications system but also impact the quality of the test data. Such variables include the ambient electromagnetic environment (EME) that the RF system is operating in; antenna placement and placement as compared to other antennas; soil properties; physical terrain; multi-ray reflection signals; desirable, undesirable, and hostile signals each disrupting functionality; and general system variability among other factors.

The multiplicity of these variables impact the quality of the data gathered and make it difficult to determine cause and effect. Basically, the results of the open air test are not repeatable, and the phenomenology is not clear.

Navy scientists have developed a device to reproduce open-air, near-earth effects in a lab setting. Known as the multi-agent radio frequency propagation simulator (MARPS) the electronics system reproduces real-world effects and accounts for all donating signal competition. The path simulator includes a system controller, data sequencer, RF path control modules, spectrum analyzer, EME generator, and device pairs for sending and receiving RF signals.

MARPS improves RF system designs, reduces the OAR testing time, saves money in the development of future RF system technology, improves the correlation between models and system performance, increases test repeatability of real environments, and increases the ability to test new real-world complications that the RF system encounters. MARPS addresses these needs by a variety of result/effects including simulating an OAR test scenario in a laboratory using a computer, other RF equipment, and a set of digitally controlled RF paths.

In one example, the MARPS device and approach could be used to test a cell phone system in the presence of interfering signals where the cell phone being tested is directly plugged into the MARPS system and the interfering devices are also directly plugged into the MARPS system. Relative signal strengths are modified, not by physically moving the RF devices or by changing the signals by adjusting the generating RF device, but instead by manipulating the MARPS system paths to simulate such interactions. As a cell phone moves through an environment, the signal strength of the cell phone will vary based on a multitude of factors including obstructions, other signals present, and even ground effects. A MARPS system can help create a more reliable cell phone or cell phone system by providing reproducible tests to developers without incurring the great expense of open-air testing. Other examples of uses for a MARPS system would be in designing more robust police scanners, garage door openers, and other RF systems.

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