Earth–Moon–Earth communication

[1] Radar reflections off the moon were received and recognized as such in 1943 during German experiments with radio measurement equipment, as reported by Dr. Ing.

It explained the gradual disappearance of the impulses by the reflecting body slowly moving out of the strongly focussed, horizontally aimed beam, as it rises above the horizon.

The first successful attempt was carried out at Fort Monmouth, New Jersey, on January 10, 1946, by a group code-named Project Diana, headed by John H.

[3] It was followed less than a month later, on February 6, 1946, by a second successful attempt, by a Hungarian group led by Zoltán Bay.

[4] The Communication Moon Relay project that followed led to more practical uses, including a teletype link between the naval base at Pearl Harbor, Hawaii and United States Navy headquarters in Washington, D.C.

In the days before communications satellites, a link free of the vagaries of ionospheric propagation was revolutionary.

EME presents significant challenges to amateur operators interested in weak signal communication.

Common modulation modes are continuous wave with Morse code, digital (JT65) and when the link budgets allow, voice.

Recent advances in digital signal processing have allowed EME contacts, admittedly with low data rate, to take place with powers in the order of 100 watts and a single Yagi–Uda antenna.

The second World Moon Bounce Day was April 17, 2010, coinciding with the 40th anniversary of the conclusion of the Apollo 13 mission.

De Paulis called the innovative technology "Visual Moonbounce" and since 2010 she has been using it in several of her art projects, including the live performance called OPTICKS, during which digital images are sent to the Moon and back in real time and projected live.

Most of the Moon's surface appears relatively smooth at the typical microwave wavelengths used for amateur EME.

As the relative geometry of the transmitting station, receiving station and reflecting lunar surface changes, signal components sometimes add and sometimes cancel, depending on their phase relationship, creating large amplitude fluctuations in the received signal.

The plane of polarization of radio waves rotates as they pass through ionized layers of the Earth's atmosphere.