|EME or Moonbounce
|Earth-Moon-Earth. Some radio amateurs communicate with each other or conduct propagation experiments by bouncing their signals off the moon. The signal losses due to the distance and reflection from the moon are very large. EME requires a very good station. With present technology, it is only just within the financial and technical reach of a radio amateur with enough knowledge and perseverance. A good EME station can also make a good radio astronomy observatory with few modifications.
|Some radio amateurs communicate by bouncing their signals off the ionization trails left by meteors. This technique is also used by military and commercial firms on a much larger scale. The channel is only open for the few seconds before the ionization dissipates and the ionization trail is mostly relatively small and weak. This means that high data rates, high transmitter powers and large antennas are required for reasonably reliable communications.
|Single Sideband. This is a very efficient way of modulating a radio signal with audio. It requires less transmit power than other modulation modes to achieve communications over a particular link. For this reason it is used extensively on long distance shortwave voice communications. For the same reason radio amateurs use it for weak signal voice communications like moonbounce.
|Continuous Wave. This is a particular name for Morse Code that has stuck, even though it does not really descibe it well. Of the 'old' modulation modes, it is by far the best in communicating over channels where the signals are very weak. For this reason most radio amateur communications on moonbounce are done using CW. It is only a few of the large amateur radio moonbounce stations that can generate enough transmitted power and have sensitive enough receivers, that can use modes like Single Sideband for voice communications on moonbounce.
|2m, 70cm, 23cm
|Amateur radio designations for specific frequency bands. The exact frequencies are allocated by international agreement, but also depend on the region and, in some cases, the particular country's requirements.
In general these bands cover more or less the following frequencies:
|VLF, VHF, UHF, L-band, S-band, C-band, X-band and Ku-band
|These are designations used for certain frequency bands. These designations are useful as the technologies and techniques differ greatly from one band to the next. It should also be noted that VLF, VHF and UHF are not part of the same system as the rest of the designations listed above. The border between VHF and UHF is sometimes a bit blurred.
These bands are specified as follows:
|A radio amateur callsign. By law, each radio amateur is assigned a callsign that must by used when communicating over the air. The first part of the callsign up to and sometimes including the numbers, shows which country the radio amateur is from (ZS = South Africa, in this case). The number often indicates which part of that particular country the radio amateur is from (1 = Western Cape, 2 = Eastern Cape, etc). The letters at the end are usually allocated sequenctially. Radio amateurs mostly get to know each other by their names AND callsigns - a bit strange, but very usefull when there are three Bobs or Petes around!
|'Meetings' held over the air. These nets are often organized to occur at regular times to discuss topics of common interest. Radio amateurs interested in EME hold nets to discuss their hobby and make appointments for EME contacts and experiments.
|Digital signal processing. Not really a radio amateur term, but one that occurs more and more in the amateur radio community and the wider electronic communications world. Signals are converted to digital form for a computer to read. Any filtering, 'amplification', etc is then done mathematically by the computer. This processing is very exact and allows accurate control over the signal's characteristics.