In sci.engr.television.advanced Dave <nospam@nowhere.com> wrote:

| From what I know about EME, amateurs use reasonably high powers, of the 
| order of 100's of Watts, with many using several thousand (not 
| officially so, but in practice they do).

There's also the big antenna gains some of them use.


| Only morse is normally used, which can be read at very low S/N ratio 
| (less than 1) in a narrow bandwidth. Single side band (SSB) is used too, 
| but signal stenghts don't often allow its use.
| 
| To use TV signals you are going to need
| 
| 1) Much wider bandwidths. At least 3-4 orders of magnitude higher. So 
| that implies signal powers 3-4 orders of magnitude higher to maintain 
| the same S/N.
| 
| 2) Much higher S/N, to decode, so even higher powers would be needed. I 
| don't know, but I doubt you could do it with a S/N or less than 30 dB.
| 
| This implies a power 6-7 orders of magnitude higher than what amateurs 
| use, which puts it into the GW power levels. It is not obvious how those 
| sorts of powers will be readily achieved.

If one wants to actually transmit information via EME, yes a lot of
power will be needed.  The original experiment was not about carrying
any information, but merely detecting the presence of the carrier.
That only needs a very very narrow bandwidth, and knowing exactly
where, and about when, it will be.

-- 
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| Phil Howard KA9WGN       | http://linuxhomepage.com/      http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/   http://ka9wgn.ham.org/ |
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