On Jan 18, 9:16*pm, (Michael Black) wrote:
David ) writes:
Kim wrote:
Test will be in CW no modulation.

http://www.arrl.org/?artid=7958

Kim

Hasn't this already been done? *With a lot less power?

An article should be self-contained, a link should merely be
to reference it. *We shouldn't have to go digging because
someone is too lazy to paraphrase what they want to talk about.
(That refers to the original poster.)

And if "RHF" and his buddies weren't so intent on jabbering
on, it would be far easier to find messages such as these.

That said, the issue is about the needed power. *Whatever
power is at the transmitter, it will be terribly attenuated
by the time it hits the moon, and then has to come back the
full distance to earth, which means the same amount of attenuation
on the return path. *We're talking massive distances compared to
terrestrial communication.

In order to get a reasonable signal when it gets back to earth, one
needs to start with a nice strong signal. *While there are issues
with the higher frequencies, a key advantage is that you can actually
get high gain antennas in reasonable size the higher you go in frequency.
So the effective radiated power can be far greater than the actual
transmitter output power. *One way of looking at is that the transmitter
signal is aimed where you want it, rather than dissipated in all directions.

The lower you go in frequency, the harder it is to get much gain in antenna,
for the simple reason that few have the space to make an antenna big enough
to get any sort of gain down there.

If you can't get the gain with the antenna, then you have to boost power
quite a bit, because a lot of it will be wasted. *The moon is a pretty
small object in the sky, yet the less directional antenna will spray
the transmitting signal all over the sky, with very little of it in
the direction of the actual moon.

A lot of moonbounce expects a reasonable gain antenna at the receiving end..

If they really expect average people to be able to receive the signal, then
that accounts for an even higger boost of power, since they have to
compensate for far lower gain at the receivers.

On *the other hand, it's far easier to generate power at 6MHz than at
2GHz. *And receivers are simpler too.

The US Signal Corp were the first to do moonbounce just after WWII, if
I remember properly it was about 110MHz, and I don't remember the power
level.

A couple of hams did it in January of 1953 on 144MHz, though it was only one
way. Two way amateur moonbounce happened in 1960 at 1296MHz.

For the handful working on it in the early days, it was easy for them
to get surplus parabolic dishes, which gave lots of gain, but then getting
enough power at that frequency was an issue. *On the other hand, unlike
the Signal Corp, the transmitter input power was limited to a kilowatt.

Receivers were a problem too, since you needed good noise figure, and
circa 1953 that meant tubes, and only a handful of relatively obscure
tubes were suitable. *Transistors helped a lot later.

When Sam Harris moved down to work at Arecibo about 1963, he got
permission a couple of times to use the actual Arecibo antenna for
moonbounce. *THat had so much gain that they apparently could hear
lots of signals from stations with no more than single yagi.

The lowest frequency that hams have done moonbounce was 50MHz, and
that didn't happen until the seventies. *I don't know if non-hams
have done any previous work at lower frequencies.

With transistors supplying good gain at VHF and above, and more
important good noise figure without all the fussing of earlier
days, amateur moonbounce has become relatively common. *It's helped
because some stations have more than enough gain on their antennas,
so simpler stations can be at the other end.

* *Michael

MB,

Thank you for your 'brief' Synopsis of the History
of Moon-Bounce Signals in your very own words.

For the Newbies out there who have never heard of Moon-Bounce
Signals and HAARP : Here are three links to learn more about
Earth-Moon-Earth (EME) Communications -aka- Moon-Bounce

7 MHz Moonbounce - Scientists Detect
http://www.southgatearc.org/news/january2008/haarp.htm
The HAARP Lunar Echo Experiment
Lowest Frequency Radar Echo From The Moon

Earth-Moon-Earth (EME) Communications
http://en.wikipedia.org/wiki/EME_(communications)

SETI League Moonbounce Signal Detections
http://www.setileague.org/eme/emepix.htm

Plus WHAT IS "HAARP" - http://www.haarp.alaska.edu/
The "High Frequency Active Auroral Research Program
http://en.wikipedia.org/wiki/High_Fr...search_Program


link-it-up {look-it-up} and learn for yourself ~ RHF