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Re: L-Band Sanity - was "being heard over LEILA siren"




    I have a few numbers for the case in point when I made contact with
HK3GAL Columbia station using L mode during the pile up example I previously
listed.
    The range = 59,495 Km, Squint = 12.5 Degs, my EIRP of 1445 watts
produced an uplink S/N of 16.3 dB on L mode.  Alon = 0, Alat = 0 for these
calculations.  These results are based on the Excel spreadsheet AO-40
Groundstation Evaluation Tool by Gene Marcus.
    From these numbers it appears my signal was approximately -12 dB below
the beacon at the time I engaged the pileup.  If we assume anything at or
less than -10 dB from the beacon is Ok then I conclude my uplink power at
the time of this event was acceptable.
    If you agree with the above calculations based on the spreadsheet then
you must agree that in this specific case the L mode worked better, could be
heard through LIELA and that I was able to make contact with HK3GAL through
the pile up on the first try while not exceeding acceptable power limits.
    If you disagree then please point out the error in the above
calculations that were made for 7/19/03 at 12:13:49 UTC that would produce a
significantly different result.   My grid is DM33up for reference at Phoenix
Arizona if you want to check these figures.   I suppose there could be some
variance in Alon Alat numbers if they were not exactly 0,0 but my assumption
is it was close to 0,0 and would not significantly change the conclusion.
If you conclude otherwise then please advise and enlighten me.
    My opinion is unchanged that it is possible to work within accepted
power levels on L mode , be heard through LEILA , and outperform a group of
U band uplinkers in a pileup.

    Best regards,

    Jim KL7QR Phoenix Arizona.

Jim Tudehope
Ham Station KL7QR:  http://www.members.cox.net/jtudehope/KL7QR.htm



----- Original Message ----- 
From: "Anthony Monteiro" <aa2tx@comcast.net>
To: "Scott Townley" <nx7u@arrl.net>; "Emily Clarke" <w0eec@AMSAT.Org>;
"AMSAT" <amsat-bb@AMSAT.Org>
Sent: Friday, August 22, 2003 6:41 PM
Subject: Re: [amsat-bb] L-Band Sanity - was "being heard over LEILA siren"


> At 04:12 PM 8/22/03 -0700, Scott Townley wrote:
>
> >One thing, Tony, is that L-band antenna gains are higher than U-band.  So
> >the sat is quite a bit more sensitive...that takes some of the 10dB
> >pathloss hit away.
> >My link budget calcs show excess uplink at the given conditions up to 17
> >degrees squint at apogee...and obviously also at even higher
squints/lower
> >ranges.
>
> Hi Scott,
>
> Yes, as I understand it, the L band antennas have around
> 5 dB more gain so you are correct and this would help
> overcome a bit of the path loss. So, I agree, it is probably
> not more than 10 dB below the beacon. Depending on the exact
> situation, it might be OK or it might be too high by a few dB.
>
> 73,
>
> Tony AA2TX
>
> ----
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