SBIR-STTR Award

Recent investigations by the DNA nuclear-effects community have identified vlf/lf link transmission frequency as a significant parameter influencing longwave communications effectiveness in MMECN/WWMCCS applications. This proposed project will address in detail the effects of frequency selection on such circuits operating in peacetime and nuclear environments, through exploratory development of models to define propagation effects over areas of varying ground conductivity and at various distances. The investigation will treat generalized longwave transmission in the northern hemisphere, but will also focus on emissions from specific VLF/LF airborne transmitters of interest to the defense community. Both TE and TM transmissions will be analyzed, and effects on both signals and atmospheric noise levels will be considered. Utilizing propagation data from existing DNA longwave databases, the investigation will develop and refine computer modeling techniques to determine generic frequency effects and will apply these results to example circuits from WWMCCS airborne transmissions. The phase I investigation will produce a final report and recommendations for phase ii effort, and an illustrated briefing of results.

Recent DNA investigations have identified VLF/LF transmission frequency as a significant parameter influencing WWMCCS/MEECN longwave communications effectiveness. Phase I of this project demonstrated the feasibility of determining the effects of frequency selection in benign and nuclear environments, and created computer models for the analysis of both TE and TM propagation in the northern hemisphere, with special consideration of frequency effects on WWMCCS airborne transmissions. Phase II will be accomplished in three parts. Part 1 will conduct research and development to apply the results of phase I to the investigation of basic phenomenology effects in nuclear environments. Part 2 will define communications effectiveness over each frequency band of interest to the WWMCCS airborne resources. Included in the latter effort will be determination of "best" and worst-case" frequencies for each WWMCCS source and each expected environment. In part 3 of the phase II program, techniques for mitigating the effects of frequency change under hostile threat scenarios will be investigated and performance improvements will be identified, based on the basic nuclear phenomenology identified by this investigation.