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Re: AO40 Spreadsheet Updated to Include Uplink Calculations



On the display page please change received power scale to indicate as much
as -70 dbm because
1) Thats what I get with the 9 foot dish
2) When I put my parameters in the sheet, all the signals move above the
display scale....off scale high
3) The other day it was reading -75 dbm max while I was tracking a close
high elevation rising pass.....
Here are my parameters:
Loss 1 0db nf 1.5 Gain 35 loss 2 2 coax 1.5 db preamp 2 coax 2 N/A 0,0,0db
Reciever NF 2.5 bw 2500. On 6/20/2001 02:32z At range 24636 at 2401
I measured power at -80dbm. I have noticed the greatest errors on the low
part of the orbit
as far as where the satellite is vs where I have to point the dish to follow
it. Maybe the elements do
a poor job simulating the orbit at that time because norad seldom gets
passes like that to measure.
Somethings off a bit but still I really do get as much as -75 dbm.
----- Original Message -----
From: "Tom Clark" <tac@clark.net>
To: "Gene Marcus" <mmarcus@hiwaay.net>; <amsat-bb@AMSAT.Org>
Sent: Sunday, June 24, 2001 10:26 PM
Subject: RE: [amsat-bb] AO40 Spreadsheet Updated to Include Uplink
Calculations


> Gene -- It's a great tool. Good job!
>
> > The revised AO40 Spreadsheet that includes uplink calculations may
> > be downloaded from:
> >
> > http://home.HiWAAY.net/~mmarcus/download/ao40v2.0.xls
>
> For good LNAs I find it easiest to measure total Tsys (Yfactor of Sky vs
> Absorber. At S-band the human body is a good 320K absorber. It brings
> new meaning to the term DUMMY load!). It appears that your calculator
> works if you use a Tsys in the antenna/sky Tsys slots, then assign the
> LNA a zero dB NF.
>
> One thing that I would find very useful: Could you add an UPLINK [NONE]
> button which would make use of the beacon power so that users could
> estimate S/N on the beacon downlinks?
>
> Tnx & 73 de Tom, W3IWI
>
> ----
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