2008 ARRL International EME Competition Results
Getting Started in Moonbounce
Moonbounce is an awesome achievement and fairly intimidating to the average ham, but it has never been more accessible than it is today. As you'll discover, the special digital signal processing (DSP) algorithms and protocols of WSJT by Joe Taylor K1JT put moonbounce within reach of even modest stations, leveraging the power of the microprocessor to copy extremely weak signals.
If the idea of making a "bank-shot" QSO over a half-million mile path sounds like it might be fun, you can get started by learning the terminology and fundamentals of EME operation. There is an HF Moonbounce Net at 1500Z on 14.345 MHz for EME operations on 432 MHz and the higher bands. It is followed by a net in support of 2 meter EME on the same frequency at 1600Z or 1700Z. This is a good place to meet hams that will answer questions (probably off-line and not during the net).
There are excellent resources online, too. Try the ARRL Technical Information Service EME pages at http://www.arrl.org/tis/info/moon.html where you'll find some QST articles and links to other moonbounce sites. N1BUG publishes a good how-to guide for the EME beginner at http://www.g1ogy.com/www.n1bug.net/operate/emebasic.html. A good US site is maintained by K7XQ at http://www.elite.net/~k7xq/k7xq.html and a good European site by DK5YA at http://www.vhfdx.de/eme.html. If you want to take a look at the EME state of the art, it is described on the home page of Leif Asbrink, SM5BSZ at http://www.sm5bsz.com. Leif's WSE modules are getting rave reviews as a dual-polarity receiver and are in use by every high-scoring moonbounce station on 144 MHz.
Analog, in the context of moonbounce, means the use of human hearing and brainpower as the means by which audio from the received echoes is translated into call signs and messages. The two modulation techniques used are CW and SSB. Of the two, SSB requires the strongest signal strength. CW signals can be detected by a highly trained and sensitive pair of ears (certainly not the author's) down into the receiver noise floor and slightly beyond in exceptional cases and circumstances. The resulting EME station is very much an alloy of operator and machine.
Digital moonbounce is dominated by the use of signal processing in the form of special protocols and codes known as JT65, part of the WSJT software suite developed and made available for free by Joe Taylor K1JT (http://physics.princeton.edu/pulsar/K1JT). His latest addition to the package is the MAP65 software that "finds" stations using the JT65 mode over a wide bandwidth—IF you have the necessary hardware and computer operating system. In these digital modes, the received audio is translated into call signs and messages by signal processing software that uses a PC sound card to digitize the audio. JT65 can dig a lot farther into the noise to recover signals than can even the best human ear. This extra ability to recover a signal is known as "processing gain." By using JT65 codes, a much more modest station can successfully complete moonbounce contacts than is required for analog modes.
A couple of long-boom Yagi's will get you "on the moon" on either 144 or 432 MHz, the two most popular bands for EME operation. There may even be a moonbouncer in your town or region that wouldn't mind showing you the ropes or you can participate on a moonbounce team. (Or start one!) You can also find moonbounce operators through the regional VHF/UHF contest clubs and those can be located those via the ARRL Club Search Web page at http://www.arrl.org/FandES/field/club/clubsearch.phtml.
With a basic station, analog moonbounce QSOs are by no means out of the question, but you will have to wait for just the right time and then take advantage of the capabilities of a seasoned moonbounce station on the other end of the path. EME contests are a good time to find these strong signals and sensitive receivers waiting for your call. In contrast, there are more opportunities for digital moonbounce operating, because of the mode's better tolerance of noise. Many stations try both analog and digital moonbounce!
With all of these resources and the excellent VHF/UHF all-band all-mode radios so widely available, the barriers to moonbounce have never been lower. Why not make it a team or club project? The Moon is closer than you think!
Page last modified: 11:08 AM, 06 Mar 2009 ET
Page author: contests@arrl.org
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