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Destination Earth via the moon by Hans van de Groenendaal ZS6AKV, corresponding editor, EngineerIT

Radio amateurs are known for their ingenuity and experimental spirit, which often takes them into territories that some believe are reserved for scientists living their lives in laboratories in search of new frontiers. Sometimes I wonder if earth moon earth communication (EME) does not belong to that category.

In radio astronomy the desired signal consists of to enhance the weak signal quest. This again noise power as well! Often, but not always, path puts to rest the prophecy from the doom loss varies over time. In space, path loss can be merchants that computers will be the death of very stable and constant over the propagation amateur radio. distances. Radio amateurs speak of so-called Joe Taylor K1JT wrote the WSJT application for “conditions”. It is the interaction of these the purpose of working meteor scatter and “conditions” with the properties of the equipment making weak signal contacts using a mode that form the weak signal domain. For a small but called FSK441. Later the weak signal modes JT44 important segment of the amateur radio world, and JT65 were introduced. These modes are this weak signal domain presents an exciting for extending the range of amateur radio VHF field of application, study, experimentation and stations in weak signal communication. observation. The name WSJT was picked by Joe to mean In the earlier days EME success was very much (Weak Signal JT). Joe’s radio call is K1JT. The dependant on huge antenna arrays and high program provides a method of saving wave power transmitters with sensitive receivers and files and saving the decoded text to a text file low noise preamplifiers fitted at the antenna. if one wishes to use these features. Distances To overcome noise and feed line losses many Hans van de Groenendaal between stations (grids) and antenna direction amateurs fit receive converters at the masthead, pointing are provided on the screen. One of its converting signals to much lower frequencies. operating modes is particularly well optimised for The output of the converter is then fed by EME communication is also known as moon amateur EME communications. WSJT is open ordinary coax cable to the receiver. bounce. It uses the moon as a passive reflector source software and is licensed under the GNU for VHF and UHF signals. Involvement in moon Software and the soundcard to the rescue general public licence. bounce by radio amateurs grew out of experiments by the military after World War II. Next to an antenna and radio, the PC and a The software supports five principal operating While the first amateur radio signals reflected sound card are important pieces of electronics modes: from the moon were received in 1953, the first two-way contact only took place in June of 1960. Using surplus parabolic dish antennas and high power klystron amplifiers, the Eimac Radio Club W6HB and the Rhododendron Swamp VHF Society W1BU achieved the first two-way EME contact on 1296 MHz. EME activity belongs to a group of activity often referred to as weak signal communication.

Weak signal communication is where radio signals have signal strength levels that are close to or partially embedded in the natural noise. The noise level is influenced by several factors such as antenna and receiver properties - the noise generated in the antenna and receiver and the noise power that is received by the antenna. The signal strength of the detected information is determined by the transmitter output, antenna gain and the path loss between the receiver and the transmit antennas.

12 September 2006 - EngineerIT Nobel Prize winner makes amateur radio his hobby

Joseph Hooton Taylor, Jr. K1JT is an American astrophysicist and winner of the 1993 Nobel Prize in Physics, shared with his former student Russell Alan Hulse, for the discovery of a new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation.

Educated at Haverford College (BA Physics 1963) and Harvard University (Ph.D. Astronomy 1968) and after a brief research position at Harvard, Taylor went to the University of Massachusetts, eventually becoming professor of astronomy and associate director of the Five College Radio Astronomy Observatory. Taylor’s thesis work was on lunar occultation measurements. About the time he completed his Ph.D., Jocelyn Bell discovered the first radio pulsars with a telescope near Cambridge, England.

Taylor immediately went to the National Radio Astronomy Observatory’s telescopes in Green Bank, West Virginia, and participated in the discovery of the first pulsars discovered outside Cambridge. Since then, he has worked on all aspects of pulsar astrophysics. In 1980, he moved to Princeton University, where he was the James S. McDonnell Distinguished University Professor in Physics, having also served for six years as faculty dean.

He has a keen interest in weak communication and developed the suite of WSJT software for weak signal experimentation by radio amateurs. He retired from teaching in 2006 and undoubtedly the amateur radio fraternity can expect some more exciting developments.

• FSK441: for meteor scatter • JT65: for EME and extreme troposcatter • JT6M: for meteor scatter (optimised for 50 MHz) • EME Echo: for measuring your own echoes from the moon • CW: for EME QSOs using 15 WPM Morse code

Local radio amateur shows how easy it really is

Even with software support it is often said that EME is difficult and that one needs massive arrays of antennas that make one’s garden look like the Sentech antenna park in Meyerton. Not so, and Hannes Enslin ZS6JDE from Pretoria proved it. He was recently on a three week visit to Zambia (9J) and operated on 2m using the WSJT software. On 25 and 26 May 2006, during only two moonrise and two moonset windows, he made a total of 20 EME contacts on 144 MHz and at least eight other stations were heard but not worked due to the basic station he was running. The station consisted of a Yaesu FT857D running 9 W into a TE Systems 400W linear amplifier and feeding a 9 element 2M antenna using low loss coaxial cable. The antenna was mounted on a portable tripod and elevated with a weight and rope system.

Of course a call like 9J2JD is sought after in the log for 2m EME everywhere in the world. But it is still quite remarkable that so many stationsw were worked in such a short time with what can be described as minimal equipment for EME.

Contact Hans van de Groenendaal, Connected Communication, Tel (012) 991-4662, [email protected] ☐

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