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<table width="100%" border="0" cellspacing="0" cellpadding="0" style="box-sizing:border-box;color:rgb(0,0,0);font-family:Verdana,Arial,Helvetica,sans-serif;font-size:medium;text-decoration-style:initial;text-decoration-color:initial"><tbody style="box-sizing:border-box"><tr style="box-sizing:border-box"><td style="box-sizing:border-box"><div id="gmail-story" style="box-sizing:border-box;width:618.667px;font-size:16px;height:auto;float:left"><h1 style="box-sizing:border-box;font-size:16pt">Ham radio technology used in Thailand cave rescue</h1><p style="box-sizing:border-box">UK radio amateur<span> </span><strong style="box-sizing:border-box">John Hey G3TDZ</strong><span> </span>(SK) designed the special low frequency radio equipment, the<span> </span><strong style="box-sizing:border-box">Heyphone</strong>, used in the recent cave rescue in Thailand<span> </span><br style="box-sizing:border-box"><br style="box-sizing:border-box">On Facebook<span> </span><strong style="box-sizing:border-box">Phil Karn KA9Q</strong><span> </span>posted:<span> </span><br style="box-sizing:border-box"><br style="box-sizing:border-box"><em style="box-sizing:border-box">Naturally I got interested in the technical aspects of the cave rescue in Thailand, particularly communications.<span> </span><br style="box-sizing:border-box">They used the "Heyphone", a voice radio designed by a UK radio ham, John Hey, G3TDZ, as open-source hardware specifically for cave rescues.<span> </span><br style="box-sizing:border-box">It uses upper (single) sideband voice on 87 kilohertz in the VLF (very low frequency) band. (That's what it says -- 87 kHz is actually LF).<br style="box-sizing:border-box"><br style="box-sizing:border-box">The "antenna" consists of two stakes driven into the ground about 20m apart. Enough of the current between them fringes outward to couple to another antenna up to a few hundred meters away (or down).<br style="box-sizing:border-box"><br style="box-sizing:border-box">John Hey passed away in 2016 so he didn't get to see his work used here. But ham radio should get some of the credit.</em><br style="box-sizing:border-box"><br style="box-sizing:border-box">Phil Karn KA9Q<span> </span><br style="box-sizing:border-box"><a href="https://facebook.com/phil.karn.98/posts/10155276627256486" target="_blank" style="box-sizing:border-box;color:rgb(0,51,102);text-decoration:none;word-wrap:break-word">https://facebook.com/phil.karn.98/posts/10155276627256486</a><br style="box-sizing:border-box"><a href="https://twitter.com/ka9q" target="_blank" style="box-sizing:border-box;color:rgb(0,51,102);text-decoration:none;word-wrap:break-word">https://twitter.com/ka9q</a><br style="box-sizing:border-box"><br style="box-sizing:border-box">John Hey G3TDZ Heyphone Cave Rescue Communication System<span> </span><a href="http://bcra.org.uk/creg/heyphone/" target="_blank" style="box-sizing:border-box;color:rgb(0,51,102);text-decoration:none;word-wrap:break-word">http://bcra.org.uk/creg/heyphone/</a></p><p style="box-sizing:border-box">Al Williams WD5GNR has written an article on Hackaday about the cave equipment<span> </span><br style="box-sizing:border-box"><a href="https://hackaday.com/2018/07/11/ham-designed-gear-used-in-thailand-cave-rescue/" target="_blank" style="box-sizing:border-box;color:rgb(0,51,102);text-decoration:none;word-wrap:break-word">https://hackaday.com/2018/07/11/ham-designed-gear-used-in-thailand-cave-rescue/</a></p></div></td></tr></tbody></table>
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