Signal would reach the Moon and bounce off in a wide range ofĬalculations for determining "Moon set" needs to be made in advance. "Moon set" at the transmitter, that is with the Moon going down as itĪpproached the Western horizon was essential, as then the maximum The Moon approximates that width as a reflector surface.
Therefore any circle arc of just half a degree, contains 6,944 watts This transmitter power is concentrated toward the visual horizon. In the United States, UHF TV bands IV and V UHF television stations are allowed to transmit a maximum ERP of 5 megawatts. In 2002, Anthony (Tony) Mann, Perth, Western Australia received the first known reception of USA UHF TV video carriers via EME propagation.Īnthony did the calculations to determine if conditions were optimum from the transmitter, a fraction of the 5 million watt UHF TV signal might be reflected off the moon and back to him in Perth. The exception is several USA UHF TV transmitters, which have an average visual ERP of 5,000 KW. The main drawback is the relatively low power of the average TV transmitter.
Since there are far more VHF and UHF ham operators compared to TV DXers, until recently, EME DXTV was not seriously explored. In most cases, only the video carrier is strong enough to be detected on a frequency spectrum analyzer. Amateurs transmit fairly high power into high gain antenna arrays, with sensitive receivers, low noise mast-mounted GaAsFET preamplifiers, and narrow modes of operation - usually the larger high gain stations only occasionally use CW or SSB.ĮME path losses vary from around 240-260 dB, hence television pictures are far too weak to be displayed on a TV screen (an exception might be if one could use the Arecibo 1,000 ft 60 dB gain dish). Also, due to jagged ridges, deep valleys and craters, the lunar surface is not an efficient reflector, since only approximately 7% of signal is reflected. Since the round trip signal path is around 480,000 miles, the received signal strengths are extremely low. EME (Earth-Moon-Earth) communication, also known as "moonbounce", is a demanding technique. Since the early 1960s, radio amateurs have made contact across continental distances at both VHF and UHF by reflecting signals off the lunar surface.
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