Ham radio operatiors have been using the moon to communicate for decades. No, they aren’t listening in to astronauts walking on the moon like I did back when I first became a ham. They are actually using the moon as a reflector to bounce a signal back toward the earth. If you have a big antenna, a fantastic receiver, and enough power you can actually make a contact this way.
In the old days of EME communication, CW was king, and repeating your call or signal report was done many many times to improve chances of success. Contacts were often scheduled in advance so as much information as possible would be known up front (like exact time to listen and frequency).
The tremendous distances involved made this a challenge for even the best equipped operators as signal loss, dopler shift, and noise often made contacts impossible. Joe Taylor, the Nobel Prize winning astrophysicist and ham, K1JT, pondered that problem and designed a brilliantly effective encoding method that actually allows signals that can’t even be heard to be decoded using advanced signal processing methods. His technique involves large amounts of redundancy, a fairly restrictive format, and the exchange for the minimum amount of information (call signs, signal reports, and locations) required for a valid contact. Thanks Joe #1 !!!
Joe Large, W6CQZ (also W4CQZ) took the work of Joe Taylor, and adapted it to HF world, enabling hams to make global contacts using minimal antennas (like a wire tossed out the window) and QRP transmitters (like the very popular FT-817). It isn’t hard at all to work half-way around the world using 5 watts or less even in sub-par band conditons.
Joe has written a fantastic program called JT65-HF that is open source and free. It can be found at this link. Joe is extreemly active supporting the software. He is very receptive to suggestions, quickly implementing good ones, and patiently listening and discussing some not so good ones. The JT65-HF user group is quite active and can be found at this link.
QST had an article written by Steven Ford on JT65-HF in the April 2011 issue on page 45. He posted an audio file of a JT65-HF signal that can be heard at this link.
I plan on blogging more about JT65 and other digital modes in the near future.
I owe Joe Large (and Joe Taylor) a debt of gratitude and a hearty hand-shake for their hard work that has benefited thousands of hams and proved, yet again, that there is always something new, fun and exciting in ham radio.
