The SETI League, Inc., a membership-supported, non-profit {501(c)(3)}, educational and scientific organization Searching for Extra-Terrestrial Intelligence

Ask Dr. SETI ®

Chapter 6: Technology

Feasibility of Amateur Active SETI

Dear Dr. SETI:

I was referred to you by an electrical engineer and amateur radio operator on IRC after asking questions regarding active SETI. The situation is as follows---I recently obtained a 10--18 GHz Rohde & Schwarz signal generator (with AM, FM, and pulse modulation, 1 kHz resolution, and frequency reference input) b/c of its very low price. I initially was planning on opening a terrestrial 3 cm amateur radio beacon transmitter, but the idea of instead opening an active SETI transmitter popped into my mind.
Would it be practical to set up an
extremely modest but quasi-continuous active SETI transmitter consisting of a server running a configurable AFSK software modem, the abovementioned generator transmitting on a non-magic but legal frequency (so within the beacon subband of amateur radio 3 cm), a Hughes 20 W TWT amplifier (which is relatively inexpensive), and a relatively small satellite dish (like 50 cm diameter) with an X-band horn? X-band waveguides will be used to the fullest extent possible to squeeze out every last mW and there will be automated and manual monitoring equipment (GPIB frequency counter, GPIB power meter, and a manual SA). KB1VYP

The Doctor Responds:

The technology you propose is relatively trivial, so of course it is practical, and would be easy to implement. However, I should point out to you that the whole question of active SETI remains a politically controversial (and indeed somewhat contentious) subject. On The SETI League website ( you will find host of articles and guest editorials discussing all sides of the issue of METI (Messaging to Extraterrestrial Intelligence).
On the top page of the SETI League website, you will find near the upper left-hand corner a link to our Google search index. Click it, and type in either METI or Active SETI, and you will see links to a host of opinions on the subject. I invite you to read them carefully before deciding to proceed.

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