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Re: [Fwd: SUN Noise]




>From: "Nick Pugh" <quadpugh@bellsouth.net>
>Hi all
>
>I am using a 2' bbq dish and a dem lnb 2400-144.  the delta noise cold sky
>to sun is 2 db
>
>The SETTI spread sheet call for an input of Jy but I think it relay is SFU
>which differ from Jy by a factor of 10,000.  Typical the SFU vary from 130
>to 160 .  My source is gopher://solar.sec.noaa.gov/00/latest/curind  
++snip++

Nick is right.  A Jansky is in units of 10^ -26 watts/meter^2/Hz whereas
the flux units in g-t.xls and the web sources for solar observations is in
units of 10^ -22 watts/meter^2/Hz...10^4 larger.  The original article
written by Richard Flagg makes this clear.  I only created a spreadsheet
from his excellent paper.  Sorry for the confusion in my earlier message
but the spreadsheet uses the larger number!  Actually the solar flux can
vary even more than Nick states and it varies over a short period of time.
Thus the need to obtain an institutional reading at the same time you make
your observations [within no more than an hour] else it may vary render
your calculations innaccurate.

The spreadsheets are found on http://www.setileague.org  ...follow the
software link and excel spreadsheet link.  A link to the paper is found in
the text describing g-t.xls.  

The noise figure spreadsheet cascade.xls is found here, too.  Gene Marcus'
program ao40_s2 calculates system NF plus more.  Cascade.xls agrees
completely with Gene's program.

Ed

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