From: Dr. H. Paul Shuch (n6tx_at_setileague.org)
Date: Mon Aug 23 2004 - 05:23:18 PDT
Jesse Young wrote:
> With my dish pointed directly at the sun, and the receiver tuned to 1420
> MHz in LSB with AGC disabled, I see a drop of about 5-10 db in my FFT
> software if I disconnect the feedline, or block the end of my feedhorn.
> Are they the sort of levels I should be seeing given that there is a
> probably a substantial amount of tweaking left for me to do?
A drop of 5 - 10 dB when you disconnect the feedline seems fairly
typical. What puzzles me is the drop when you block the feedhorn.
Whatever you're blocking it with (presumably yourself) is a warm body,
and should generate considerable thermal radiation. A better test, if
you're seeing sun noise, is to establish the *difference* in signal
level between pointing at the sun and pointing at cold sky. This will
allow you to quantify system performance, through the G/T method, as
outlined at <http://www.setileague.org/articles/g-t.htm>.
> PS
>
> I do have the intention of joining SETI League, and hopefully becoming a
> Project Argus participant, but my set-up is sort of a school project at
> the moment and I'd like to have it functioning at a reasonable level
> before I go any further.
If you're at the point of being able to see sun noise, you are certainly
far enough along that you should consider registering your Project Argus
station. Also, these kinds of technical discussions should best take
place on the Argus email list, which was established for this very
purpose, not on the general-interest Public list. Yes, station
registration and Argus list participation required SETI League
membership. But you say this is a school project, so I presume you are
a full-time student, thus eligible for half-price Scholarship
Membership. I hope you'll be joining us!
Yours for SETI success,
Paul
-- H. Paul Shuch, Ph.D. Executive Director, The SETI League, Inc. 433 Liberty Street, PO Box 555, Little Ferry NJ 07643 USA voice (201) 641-1770; fax (201) 641-1771; URL http://www.setileague.org email work: n6tx_at_setileague.org; home: drseti_at_cal.berkeley.edu "We Know We're Not Alone!"
This archive was generated by hypermail 2.1.6 : Mon Aug 23 2004 - 06:01:03 PDT