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RE: Oscar 0



>  Here's an interesting article that I enjoyed so much that I 
> printed it out, and
> since the subject has sort of came up, here's the URL. Check 
> it out and kick the
> idea around a little. Always interesting to see what others 
> think as well.
> 
> http://www.qrz.com/features/Artemis/page1.html

Interesting.  Hmm, I think his link estimates might be a bit optimistic, but
the idea has merit.  The signal from the lunar transponder should be a tad
less than 20dB down on what one can expect from P3D when it flies, if the
antenna gains are the same (which is likely, if a fixed array aimed at Earth
is used, rather than a sterrable array)..  Yes, the long lunar night would
present some problems.

The 20dB figure comes from a rough guesstimate based on the different
distances of P3D and the moon, combined with the inverse square law.

P3D will appear at up to around 52000km from the observer.  The moon is
approximately 400000 km away, or around 8 times further away, which means a
signal attenuation of approx 60 times more than the trip to P3D would
involve, or a power ratio of approximately 18dB.

So if 10W and a small Yagi will hit P3D, then you'd need 100W and a long
Yagi to make the trip to the lunar transponder.

As I said, rather rough, but it should give a ballpark feeling for the link.

I raise a couple of other questions about the article.  The Internet isn't
the dragon that's about to swallow ham radio.  They're quite different
activities which will interest different people.  In fact, the Internet is
one of our greatest allies, a medium which allows us to publicise the hobby,
make contact with potential new hams and show people what we _can_ do with
ham radio.  I hope that we will no longer be "that guy with all the wierd
things on the house down the road", but instead, we will be known by the
world through our web sites.  Radio will always fascinate some people, and
it is these people we want to get in touch with.

As an example, a friend of mine in Sydney only found out about ham radio
because we chat on IRC, and every now and then, I'd pop a message in the
channel like "Gotta run, satellite's coming".  He asked about this satellite
thing, so I told him, and when he came to melbourne on a holiday visit, we
went and had a play on UO-14 with a couple of HTs.  The demo went across
well, he's now studying for his ticket.

I asked him why he didn't get into ham radio, and the answer was "I didn't
know it existed!".  Surely we can do a better job of self-promotion in the
community.  Where were the hams when there was someone wanting to join the
ranks? (he has had a lifelong interest in communications).

Similarly, I've had great responses from the general public with satellite
demonstrations at hobby fairs and the like, it goes over well.
Surprisingly, some visitors want to see things like Morse Code (yes, there
is a bit of interest in Morse from the public!), and one of the guys at the
stand had to setup his rig to act as a practice oscillator for people to
play with. :-)

A lunar transponder would be interesting from a technical POV, and would be
good for publicity (and definitely a contribution to the radio art), but we
also need to do the groundwork in our every day activities, and utilise the
phenomenon of the Internet to our advantage, both technically (which we do
well with wormholes, Igates and now voice repeater links), and socially.

<steps off soapbox>

:-)
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