OK, I\u2019d been bouncing signals off the Moon ever since I put up the antenna system a fortnight before. Just that I didn\u2019t know there was anyone on the other end to decode my 13-character message. Until, that is, on the 12th<\/sup> Mr Potts, callsign NC1I, replied from Massachusetts, USA.<\/p>\n\n\n\n Moonbounce (or Earth-Moon-Earth, EME) communication is a very cool thing to do. Just imagine the cred you\u2019d get when next in a bar and you throw that out there when things go quiet.<\/p>\n\n\n\n And importantly, anyone can do it.<\/p>\n\n\n\n The Moon is about 400,000km away (less at perigee, more at apogee). Hence, the flight time for a signal from Earth to Moon and back is about 2.7 seconds. The corresponding round-trip free-space path loss for a signal is a huge 400dBi \u2013 no way anyone can bridge that gap. But whilst the Moon is a poor point reflector with a reflection coefficient of 6.5%, it\u2019s also a 3,500km diameter billboard that reflects from all points across its area. The result is a real total path loss of around 250dBi and that\u2019s (just) low enough for radio amateurs to exploit our natural satellite to communicate almost globally.<\/p>\n\n\n\n Today, almost everyone uses Joe Taylor (K1JT)\u2019s ultra-narrow-band algorithms to code and send a very short message. The message is pared to the bone \u2013 it\u2019s even skinnier than FT8. And using his software, WSJT-X<\/a>, this is sent repeatedly. So, you need a computer, a sound card, and the application. The setup is the same as for FT8, but you\u2019ll configure to use Q65B with a 60-second period.<\/p>\n\n\n\n![\"\"](\"http:\/\/galaradioclub.co.uk\/wp-content\/uploads\/2024\/05\/First-EME-QSO.jpg\")
<\/a>Background<\/h2>\n\n\n\n
Basic Kit<\/h2>\n\n\n\n