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CX2SA > SATDIG 12.04.11 21:05l 296 Lines 10584 Bytes #999 (0) @ WW
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Sent: 110412/1903Z @:CX2SA.LAV.URY.SA #:64660 [Minas] FBB7.00e $:AMSATBB6211
From: CX2SA@CX2SA.LAV.URY.SA
To : SATDIG@WW
Today's Topics:
1. Re: satellite average elevation (Bob Bruninga)
2. Re: satellite average elevation (Joe)
3. Re: satellite average elevation (Mark L. Hammond)
4. Re: satellite average elevation (Andrew Glasbrenner)
5. Re: ARISSatTLM Software Now Available for Apple Mac
(Edward R. Cole)
----------------------------------------------------------------------
Message: 1
Date: Tue, 12 Apr 2011 14:24:38 -0400
From: "Bob Bruninga" <bruninga@xxxx.xxx>
Subject: [amsat-bb] Re: satellite average elevation
To: <amsat-bb@xxxxx.xxx>
Message-ID: <010301cbf93e$e1d7b590$a58720b0$@xxx>
Content-Type: text/plain; charset="us-ascii"
> As I said, in the "goode olde dayes" we used
> 30 degree up tilt and it worked well...
> Lessening the up tilt may increase the gain
> for the lower angle passes but will also decrease
> the gain on the higher angle passes. So, it is a
> "trade off" no matter what you do!
Sorry to sound like I am quibbling... but that last sentence implies the
idea of an equal "trade off". But the tradeoff is not equal at all and may
be missing the point here.
A LEO satellite pass does not need gain at "higher angles" because the
satellite is by definition 2 or 3 times closer to the ground station (+6 to
+9dB stronger). But one does need the gain at lower angles where the
satellite is much further away.
An up-tilt of 30 degrees is throwing away excess gain where it is not needed
(high angles) at the expense of low angles where every single dB -is-
needed. So there is no real tradeoff... A lower angle (about 15 degrees)
is more-or-less optimum for LEO's with fixed tilt and modest gain beams.
To actually quantify the exact best angle (which will depend on the actual
beam's own beamwidth), it is simply to up-tilt the antenna no more than the
angle at which the gain on the horizon LOSES say less than 1 dB. Note, this
is not half the published "antenna beamwidth" which is usually a "3 dB"
beamwidth. It is much less than that, less than half the 1 dB beam width.
You can measure this by setting the beam no higher than the upangle that
loses less than 1 dB to a signal on the horizon....
Something like that...
Bob, WB4APR
------------------------------
Message: 2
Date: Tue, 12 Apr 2011 13:38:26 -0500
From: Joe <nss@xxx.xxx>
Subject: [amsat-bb] Re: satellite average elevation
To: amsat-bb@xxxxx.xxx
Message-ID: <4DA49C22.1050109@xxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Need to take into account also that the main lobe of a bean even flat on
the horizon the max center of the main lobe is still not also dead on
the horizon but elevated some due to ground reflections.
Joe WB9SBD
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 4/12/2011 1:24 PM, Bob Bruninga wrote:
> X-Antispam: NO; Spamcatcher 6.1.2. Score 1
>
>> As I said, in the "goode olde dayes" we used
>> 30 degree up tilt and it worked well...
>> Lessening the up tilt may increase the gain
>> for the lower angle passes but will also decrease
>> the gain on the higher angle passes. So, it is a
>> "trade off" no matter what you do!
> Sorry to sound like I am quibbling... but that last sentence implies the
> idea of an equal "trade off". But the tradeoff is not equal at all and may
> be missing the point here.
>
> A LEO satellite pass does not need gain at "higher angles" because the
> satellite is by definition 2 or 3 times closer to the ground station (+6 to
> +9dB stronger). But one does need the gain at lower angles where the
> satellite is much further away.
>
> An up-tilt of 30 degrees is throwing away excess gain where it is not needed
> (high angles) at the expense of low angles where every single dB -is-
> needed. So there is no real tradeoff... A lower angle (about 15 degrees)
> is more-or-less optimum for LEO's with fixed tilt and modest gain beams.
>
> To actually quantify the exact best angle (which will depend on the actual
> beam's own beamwidth), it is simply to up-tilt the antenna no more than the
> angle at which the gain on the horizon LOSES say less than 1 dB. Note, this
> is not half the published "antenna beamwidth" which is usually a "3 dB"
> beamwidth. It is much less than that, less than half the 1 dB beam width.
> You can measure this by setting the beam no higher than the upangle that
> loses less than 1 dB to a signal on the horizon....
>
> Something like that...
> Bob, WB4APR
>
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 3
Date: Tue, 12 Apr 2011 14:39:55 -0400
From: "Mark L. Hammond" <marklhammond@xxxxx.xxx>
Subject: [amsat-bb] Re: satellite average elevation
To: Bob Bruninga <bruninga@xxxx.xxx>
Cc: amsat-bb@xxxxx.xxx
Message-ID: <BANLkTi=pUQ=WciJSXzPZXPk4g+K9ssfVYg@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Okay---but the 12-15 degree argument _assumes_ that the station has a
view "to the horizon" that isn't tainted by trees, hills, and houses.
In those circumstances, 30 deg might well be the better choice! I
know it would be where my array is at currently.
So, the 12-15 degree "optimum" assumes a clear view to the horizon...right??
Mark N8MH
On Tue, Apr 12, 2011 at 2:24 PM, Bob Bruninga <bruninga@xxxx.xxx> wrote:
>> As I said, in the "goode olde dayes" we used
>> 30 degree up tilt and it worked well...
>> Lessening the up tilt may increase the gain
>> for the lower angle passes but will also decrease
>> the gain on the higher angle passes. ?So, it is a
>> "trade off" no matter what you do!
>
> Sorry to sound like I am quibbling... but that last sentence implies the
> idea of an equal "trade off". ?But the tradeoff is not equal at all and may
> be missing the point here.
>
> A LEO satellite pass does not need gain at "higher angles" because the
> satellite is by definition 2 or 3 times closer to the ground station (+6 to
> +9dB stronger). ?But one does need the gain at lower angles where the
> satellite is much further away.
>
> An up-tilt of 30 degrees is throwing away excess gain where it is not needed
> (high angles) at the expense of low angles where every single dB -is-
> needed. ?So there is no real tradeoff... ?A lower angle (about 15 degrees)
> is more-or-less optimum for LEO's with fixed tilt and modest gain beams.
>
> To actually quantify the exact best angle (which will depend on the actual
> beam's own beamwidth), it is simply to up-tilt the antenna no more than the
> angle at which the gain on the horizon LOSES say less than 1 dB. ?Note, this
> is not half the published "antenna beamwidth" which is usually a "3 dB"
> beamwidth. ?It is much less than that, less than half the 1 dB beam width.
> You can measure this by setting the beam no higher than the upangle that
> loses less than 1 dB to a signal on the horizon....
>
> Something like that...
> Bob, WB4APR
>
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
--
Mark L. Hammond [N8MH]
------------------------------
Message: 4
Date: Tue, 12 Apr 2011 14:45:30 -0400 (GMT-04:00)
From: Andrew Glasbrenner <glasbrenner@xxxxxxxxxx.xxx>
Subject: [amsat-bb] Re: satellite average elevation
To: Bob Bruninga <bruninga@xxxx.xxx>, amsat-bb@xxxxx.xxx
Message-ID:
<7200217.1302633931431.JavaMail.root@xxxxxxxxxxxxxxx.xxx.xx.xxxxxxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Gentlemen,
Your difference of opinion may stem from the fact that AO-6 through AO-8 had
orbits that were in the 1450km range, and not the 600-800km that is more
common now. That might hose up the numbers some, as the angles and path
losses are considerably different.
You just might be _BOTH_ right for the assumed scenario.
73, Drew KO4MA
-----Original Message-----
>From: Bob Bruninga <bruninga@xxxx.xxx>
>Sent: Apr 12, 2011 2:24 PM
>To: amsat-bb@xxxxx.xxx
>Subject: [amsat-bb] Re: satellite average elevation
>
>> As I said, in the "goode olde dayes" we used
>> 30 degree up tilt and it worked well...
>> Lessening the up tilt may increase the gain
>> for the lower angle passes but will also decrease
>> the gain on the higher angle passes. So, it is a
>> "trade off" no matter what you do!
>
>Sorry to sound like I am quibbling... but that last sentence implies the
>idea of an equal "trade off". But the tradeoff is not equal at all and may
>be missing the point here.
>
------------------------------
Message: 5
Date: Tue, 12 Apr 2011 10:42:29 -0800
From: "Edward R. Cole" <kl7uw@xxxxxxxxx.xxx>
Subject: [amsat-bb] Re: ARISSatTLM Software Now Available for Apple
Mac
To: "JoAnne Maenpaa" <k9jkm@xxxxxxx.xxx>, <amsat-bb@xxxxx.xxx>
Message-ID: <201104121846.p3CIkSC0052720@xxxxxx.xxxxxxxxx.xxx>
Content-Type: text/plain; charset="us-ascii"; format=flowed
At 04:21 AM 4/12/2011, JoAnne Maenpaa wrote:
>Hello everyone,
>
>Making sure this gets wider coverage than the ANS list:
>
>SB SAT @ AMSAT $ANS-102.02
>Mac Version of ARISSatTLM Software Now Available for Download
>
>AMSAT News Service Bulletin 102.02
> >From AMSAT HQ SILVER SPRING, MD.
>April 12, 2011
>To All RADIO AMATEURS
>BID: $ANS-102.02
>
>The Mac version of the ARISSatTLM software is now available for
>download from:
>
>http://www.arissattlm.org/download/ARISSATTLM.zip
>
>[ANS thanks the ARISSat-1 team for the above information]
>
>/EX
>
>--
>73 de JoAnne K9JKM
>k9jkm@xxxxx.xxx
>Editor, AMSAT News Service
I guess I missed the announcement for the PC Telemetry sw. But found
it and now installed. Still remains to see if my omni antenna will
be adequate once ARISSat-1 is operating.
73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ 500 KHz - 10-GHz www.kl7uw.com
EME: 144-1.4kw, 432-100w, 1296-testing*, 3400-winter?
DUBUS Magazine USA Rep dubususa@xxxxxxx.xxx
======================================
------------------------------
_______________________________________________
Sent via amsat-bb@xxxxx.xxx. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
http://amsat.org/mailman/listinfo/amsat-bb
End of AMSAT-BB Digest, Vol 6, Issue 211
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