A desirable interface between multi-agents is through over-the-air RF connections that include not only the intended direct RF communications paths but also highly variable multi-ray propagation, range attenuation, external RF influences, and near-earth influence. These influences are all difficult to predict, control, and repeat in an outdoor environment. This outdoor testing, as has traditionally been done, is extremely expensive while simultaneously providing fewer data points than more controlled events and the testing events are generally not repeatable.
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 (OAR) 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 impacts the quality of the data gathered and makes 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 signal propagation simulator determines the performance of a communications system prior to OAR testing.
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 results/effects including simulating an OAR test scenario in a laboratory using a computer, other RF equipment, and a set of digitally controlled RF paths.
The MARPS device and approach could be used to test a cellphone system in the presence of interfering signals where the cellphone 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 cellphone moves through an environment, the signal strength of the cellphone 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 cellphone or cellphone 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.