Bob Bruninga, WB4APR, led a group of radio amateurs earlier this month to Mammoth Cave — the world’s longest known cave system — at Mammoth Cave National Park in Kentucky to test how the Automatic Packet Reporting System (APRS) can be used as a means to extend radio communications underground. “When used underground, VHF and UHF radios can only work within a few hundred feet of each other and…
American Radio Relay League | Ham Radio Association and Resources