Wednesday, May 29, 2013

Earth Moon Earth

One of the things that has always interested me is doing an Earth Moon Earth contact. I remember trying to listen for my own echo by pointing the direction antenna from my school at the moon and bouncing an FM voice signal off of it (It takes seconds for the light path to connect back up, thus it is common to hear your own echos off of the moon). I wasn't successful.

An EME contact, simply put, is one where you use the moon to bounce signal off of and talk to someone else on the ground. This is often considered the pinnacle of VHF communications, and can in fact allow for worldwide communication, but it can be a bit tricky to perform. I am going to borrow some information from my elmer in this area, Paul, K4MSG, and specifically his article entitled "EME on a budget". This will include some of my own research on the subject as well.

 So, how does one start to attempt an Earth Moon Earth jump? The bottom line is, you need 4 things to have any chance of success at all, along with the supporting infrastructure for said devices.

1. A radio capable of SSB transmission (For digital use), preferably VHF
2. A directional antenna
3. A computer that can hook up to your radio.
4. A good pre-amp/ amplifier

The last is important because digital communications can pick out signals in the noise better than CW. SSB via the moon is almost impossible, and don't even bother with FM. My first attempt at an EME contact was doomed because of that...
Surprisingly, the most difficult thing to get on that list seems to be the SSB radio for use over a VHF. The only time that I can see a radio that can do that is for those radios that also do HF, where SSB rules. Still, that's something to keep in mind. As of right now, I do not know what type of radio I might get to fulfill this requirement.

My directional antenna of choice to start out with will be a dual yagi antenna from Arrow Antenna. Amplifier is a bit trickier, but I'm looking at the Mirage amplifier B-320-G.

I haven't yet tried this, but I am very much looking forward to giving it a shot. It definitely requires a lot of power, but I'm hoping to make it work sooner or later...

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