Trying to find an inexpensive way to verify the possibility of NVIS communication before actually doing it. It may require a 1-millisecond transmission followed by about 3 to 8 milliseconds of listening for the echo.
Its main usefulness will be for emergency communication setup in a single union state environment by eliminating the conventional HF skip zone and reaching between mountains, hills, and large buildings.
The removal of an up-front uncertainty is most important when no other communication method is available.
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