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R: sun noise




----- Original Message -----
From: Nick Pugh <quadpugh@bellsouth.net>
To: <amsat-bb@AMSAT.Org>
Sent: Tuesday, January 01, 2002 3:56 PM
Subject: [amsat-bb] sun noise


> how much noise should you expect with the below listed perimeters
>
> ant gain 15 dbdc
> preamp .8 db
> SFU 42 e^-22
>
> happy new year nick k5qxj
>
>
Hi Nick,

In order to make this calculation it is necessary to know exacly the numbar
of  sfu  or Solar Flux Units  and the frequency at wich the numbar of  sfu
has been measured and referred.

1 sfu = 10 E -22 W/m^2 per Hz of  bandwidth  of  radio frequency energy and
1 sfu is 10.000 time greater than  the Jansky unit used by radioastronomers
( 1 jansky = 10 E -26 W /m^2 per Hz of  bandwidth of  radio frequency
energy.)

Also it is necessary to know the frequency at wich you want to do the
calculation.

In addition it is necessary to know the overall noise figure of your
receiving system and not only that of your preamplifier alone.

For example,the Noise Figure of your preamplifier alone can be NF=0,8 dB but
the overall  NF of your receiving system can be much greater than 0,8 dB if
the NF of your converter/receiver is  very high and if the gain of your
preamplifier is very low.

You wrote that the gain of your antenna is 15 dBdc but i suppose you want to
write 15 dBic

In any case the power noise received by the sun do not change changing the
antenna polarization because it is a withe random noise to be considered no
polarized and so no difference if you receive it with linearly or circularly
polarized antennas.

The sfu data for every day are available from the U.S. Dept of Commerce,
 NOAA ,Space Environment Laboratory at the following address:

gopher://proton.sel.noaa.gov:70/11/lists/radio

For more detailed information on this measurements please read the ARRL,
UHF/Microwave Experimenters Manual: Order Nr 3126
Chapter 7 "Estimating Microwave System Performance";Calculating
 System noise Temperature";Noise Temperature,Antenna Temperature
and  Sun Noiose";
by Bob Atkins, KA1GT

And also:

"Microwave System Calibration using the Sun and Moon"; by David B. Shaffer,
W8MIF

A very nice program for this calculation is:

NOISE.EXE Solar Noise Calculator Ver. 3.1 by Melvin B. Graves, WR0I
705 E 117th N
Sedgwick, KS 67135 U.S.A.

73 de i8CVS Domenico

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