Circuit Integrity Analysis
The ACE (Animated Communications Effectiveness) concept was developed for the U.S. Navy and first applied to VLF submarine communications. VLF signaling is the preferred method for such applications because the signals can be heard over great distances and can penetrate sea water, thus permitting the submarine to remain hidden below the surface. For many decades, propagation models using waveguide theory (where waves are assumed to propagate between the D-region of the ionosphere and the earth's surface) have been conceived and fine-tuned. Today, validated and accurate models for under-sea VLF reception exist.
As the VLF models grew more complex, so did the problem of depicting the result. For years, it was common practice to plot area coverage curves on paper. But at VLF, such plots varied greatly with transmit power, signaling mode and other factors, including time-of-day. An oft-used simplification was to assume an all-daytime scenario because daytime coverage was easier to understand and, in general, was worse than nighttime coverage. But in fact, nighttime signal fading often causes severe signal drop-outs in many areas, and those effects were missed when only a simple coverage prediction at one time-of-day was made.
To understand these effects, the authors of the ACE programs began to produce hourly curves and hang the papers on the wall. But soon, the walls were totally covered because every revelation suggested changing another system variable and producing another set of paper. Eventually, the solution was to show the curves on a computer screen in succession; the ACE concept was born.
The ACE method shows a sequential series of coverage maps, with multiple curves as needed to describe the effect of changing system variables. When showing the maps one after the other, a movie-like display is produced. In fact, the program that displays the sequential coverage maps is called MOVIE. The images may be shown one at a time, or repeated rapidly at various speeds.
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ACE-VLF Copyright © 2007 by
Richard P. Buckner, P. E.
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