On 15 Oct 2005 23:06:50 GMT, phil-news-nospam@ipal.net wrote:

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.

To count as a valid contact, calls, signal reports, and geographic
location must be exchanged.

As I mentioned in an earlier post, this month's QST has an article
about an *accidental* EME contact on the 2-meter band (144-148 MHz)
using WSJT (digital mode)

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com