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earthstation
2013-Mar-12, 11:29 AM
I am hoping to build a transmitter for amateur METI, probably a klystron or gyrotron. I have a background in Electrical Engineering, but little knowledge of the plasma/particle physics necessary. I'm planning to begin studying the necessary material full time in less than a year. I looked around for commercially available devices, but there doesn't seem to be anything available off the shelf and custom devices would be far too expensive for me to afford. I also searched for a physicist who might be able to do the design work for me, but also have not found anyone. I'm thinking in terms of 300 kW, 10 Ghz, 0.3s pulse width, and pulse position modulation. Transmitting sites in Peru or Argentina for targeting southern hemisphere stars within 25 ly. I've considered using the L3 Communications PM2000x 9.3 Ghz 2 MW 4 uS pulsed coaxial magnetron, but due to the wide bandwidth of those short pulses it doesn't appear to provide enough range to reach even Alpha Centauri assuming a 100m receiving dish at the other end. It seems that a GW class device would be needed for such short pulses.

Suggestions, advice, comments, or questions are all welcome. If anyone wants to help with the project PM me.

edit: oops, I meant 0.3 seconds, not microseconds; long pulses, not short ones. I shouldn't post while sleep deprived. That's why neilzero probably mentioned the H2 thyratron which isn't really necessary but nice at 1/3 second pulse lengths. But of course thyratons are just cool anyway.

neilzero
2013-Mar-12, 01:36 PM
Wecome to CosmoQuest forum. Are you planning to talk to ET in English, boolian, digital or other? Ten ways might be good = sort of like a Rosetta stone. A gyratron is a solid state device simular to technology used for HVDC = high voltage direct current power lines? If you succeed and ET comes here to make us human slaves, you will be infamous.
Hydrogen thyratrons were used to make 0.1 microsecond pulses as early as 1953, so those won't be leading edge short pulses. Neil

earthstation
2013-Mar-12, 11:10 PM
I'm not sure what sort of communication I'd be using. I would be using the pauses between pulses to encode the data though. Each pause length could represent a different symbol or idea perhaps.

The gyrotron that I am interested in is not solid state. It is a high voltage electron beam which uses a magnetic field induced rotational motion of electrons in an annular beam to amplify the input RF.

I'll probably end up using a hydrogen thyratron to switch a pulse forming network to create my pulses even though they are long. I want the pauses between pulses to be as accurate as possible.

Success is terribly unlikely. If there really were an advanced civilization within a mere 40 ly of earth they would already have detected us with their kilometer scale optical telescopes. They would have detected the methane and nitrogen/oxygen in the atmosphere and known what that meant. Hell, they would probably have planetary scale radio telescopes which could detect even our faint radio emissions. They would already know about us. They would already have been here. If they had wanted us dead or enslaved we would already know about it.

So why bother with sending messages to such close targets if there is almost certainly no intelligent life there? Because it's cool, like living in a scifi novel, and because I might be wrong. In that highly unlikely event and if they turned out to be hostile then yes I would have betrayed my entire species and maybe even all life on the planet. If the aliens did come and decided to exterminate the infestation would I be guilty of, to borrow a Iain Banks phrase, gigadeathcrime?

ASTRO BOY
2013-Mar-16, 04:27 AM
I am hoping to build a transmitter for amateur METI, probably a klystron or gyrotron. I have a background in Electrical Engineering, but little knowledge of the plasma/particle physics necessary. I'm planning to begin studying the necessary material full time in less than a year. I looked around for commercially available devices, but there doesn't seem to be anything available off the shelf and custom devices would be far too expensive for me to afford. I also searched for a physicist who might be able to do the design work for me, but also have not found anyone. I'm thinking in terms of 300 kW, 10 Ghz, 0.3 uS pulse width, and pulse position modulation. Transmitting sites in Peru or Argentina for targeting southern hemisphere stars within 25 ly. I've considered using the L3 Communications PM2000x 9.3 Ghz 2 MW 4 uS pulsed coaxial magnetron, but due to the wide bandwidth of those short pulses it doesn't appear to provide enough range to reach even Alpha Centauri assuming a 100m receiving dish at the other end. It seems that a GW class device would be needed for such short pulses.

Suggestions, advice, comments, or questions are all welcome. If anyone wants to help with the project PM me.



Hi earthstation!

What can I say?......I'm not in a position to offer any technical advice but I will say a fair dinkum "Good onya mate!"
We all know chances of finding anything are slim, but it does take someone special, who despite those odds, will still take the time and make the effort.

Why not contact SETI itself and see what advice they can give?

http://www.seti.org/contact

earthstation
2013-Mar-17, 08:40 AM
Assuming they even wanted to help, I don't think there is much chance that anyone at the SETI Institute would have useful advice for building microwave transmitters. Receivers and dishes maybe, although they probably just buy them. My biggest problems are engineering ones: building a klystron and maybe a 20 meter dish, but mainly designing/building the klystron. I need the help of physicists and electrical engineers with high power microwave knowledge, which is pretty rare these days. I suppose there might be someone there who could point me in the right direction, but I don't know how I would manage to get in touch with them in particular.