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CX2SA > SATDIG 14.10.08 01:25l 607 Lines 19351 Bytes #999 (0) @ WW
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To : SATDIG@WW
Today's Topics:
1. Re: AO-51 SIGNAL? (Alan P. Biddle)
2. Re: ARISS images (Ransom, Kenneth G. (JSC-OC)[BAR])
3. "Flea Power" follow up (n3tl(AT)bellsouth.net)
4. Jamboree on the Air on AO-51, 18-19 October 2008
(Andrew Glasbrenner)
5. Re: ARISS images (Gordon JC Pearce MM3YEQ)
6. manual keplerian calculations (Jeff Wandling W7BRS)
7. Re: manual keplerian calculations (Simon (HB9DRV))
8. Re: manual keplerian calculations (cathrynham)
9. Re: manual keplerian calculations (Gordon JC Pearce MM3YEQ)
10. Re: manual keplerian calculations (Simon (HB9DRV))
11. Re: manual keplerian calculations (Alexandru Csete)
12. Re: manual keplerian calculations (Simon (HB9DRV))
13. Re: manual keplerian calculations (Simon (HB9DRV))
----------------------------------------------------------------------
Message: 1
Date: Mon, 13 Oct 2008 10:04:16 -0500
From: "Alan P. Biddle" <APBIDDLE(AT)UNITED.NET>
Subject: [amsat-bb] Re: AO-51 SIGNAL?
To: <amsat-bb(AT)amsat.org>
Message-ID: <6B12ADFDD4C14F20A29D68D76E9DC197(AT)WA4SCA>
Content-Type: text/plain; charset="us-ascii"
Doug,
Speaking generally, satellites are not symmetric, often but not always
locked to the Earth's magnetic field lines, and everything from the gain to
the circularity depends on "how you look at it." The antenna may be
partially blocked, and far off axis a circularly polarized system becomes
elliptical, and may even reverse direction.
I have enough RX gain that it is never a problem hearing AO-51, but I do
notice there is some variation, particularly WRT polarization. Likewise, I
can always uplink on Mode-L, but there is a distinct difference in the power
required depending on the direction of the pass.
You mentioned both a beam and a vertical. More details would help to
determine whether you are "doing anything wrong," but it sounds as if your
gain is low enough that you are hearing the difference a few db makes. The
usual questions would be length and quality of coax, pointing accuracy for
the beams, use of a low noise preamp, etc.
Alan
WA4SCA
------------------------------
Message: 2
Date: Mon, 13 Oct 2008 10:05:00 -0500
From: "Ransom, Kenneth G. (JSC-OC)[BAR]" <kenneth.g.ransom(AT)nasa.gov>
Subject: [amsat-bb] Re: ARISS images
To: "Gordon JC Pearce MM3YEQ" <gordonjcp(AT)gjcp.net>,
<amsat-bb(AT)amsat.org>
Message-ID:
<A2862DA1C49F4145AF6C2A452829403501C919A2(AT)NDJSEVS21A.ndc.nasa.gov>
Content-Type: text/plain; charset="iso-8859-1"
Yesterday's tests were on a limited scale. The full operation is not expected
to start up until Garriott is aboard on Oct 14.
Kenneth - N5VHO
________________________________
From: amsat-bb-bounces(AT)amsat.org on behalf of Gordon JC Pearce MM3YEQ
Sent: Mon 10/13/2008 9:17 AM
To: amsat-bb(AT)amsat.org
Subject: [amsat-bb] Re: ARISS images
Gordon JC Pearce MM3YEQ wrote:
> Maybe I'm doing it wrong, or maybe they're not transmitting over the UK.
> I didn't hear *anything* with either a J-pole, homebrew 3-ele Yagi or
> 6-ele quad on the pass at 14:06UTC...
>
> Gordon
>
_______________________________________________
Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
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Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 3
Date: Mon, 13 Oct 2008 15:06:30 +0000
From: n3tl(AT)bellsouth.net
Subject: [amsat-bb] "Flea Power" follow up
To: AMSAT-BB(AT)amsat.org
Message-ID:
<101320081506.4266.48F363F60000A498000010AA22218801869B0A02D2089B9A019C0
4040A0DBF049BCC02(AT)att.net>
Content-Type: text/plain; charset="utf-8"
Hey everyone,
Over the weekend, I ended up working four passes of AO-51 running 300
milliwatts out of my Yaesu VX-7R HT, which was powered for these passes by 2
AA Duracell batteries. I used the Elk 2M/440L5 log periodic antenna - handheld
- for all four passes.
Here are some numbers:
I made a total of 11 contacts in the 4 passes (1 with 4 contacts, 1 with 3,
and 2 with 2).
The average elevation of the satellite during these 11 contacts was 34.1454
degrees. The average range was 1,364.0726 kilometers/847.5954 miles.
A contact with KG4ZLB at 00:26 UTC on 12 October found the satellite closest
to me of any contact ? 53.5 degrees at a range of 959.810 kilometers/596.3995
miles. A contact with WD9EWK at 01:09 UTC on 11 October found the satellite at
its most distant for any contact ? 12.3 degrees at a range of 2,197.771
kilometers/1,359.418 miles.
That was fun!
I?m now really looking forward to the last week of the month, when the
?regular? FM pair is scheduled (based on what I read on the Web site Sunday
night) to be configured for SSB up and FM down ? the opposite of AO-16?s
current, very unique mode (the downlink actually is dual sideband, and many of
you likely have read in AMSAT Journal coverage of AO-16?s rebirth).
73 to all,
Tim ? N3TL
AMSAT Member No. 36820
Athens, Ga. ? EM84ha
------------------------------
Message: 4
Date: Mon, 13 Oct 2008 11:19:35 -0400
From: "Andrew Glasbrenner" <glasbrenner(AT)mindspring.com>
Subject: [amsat-bb] Jamboree on the Air on AO-51, 18-19 October 2008
To: <amsat-bb(AT)AMSAT.Org>, <ao51-modes(AT)AMSAT.Org>, "ans-editor"
<ans-editor(AT)AMSAT.Org>
Message-ID: <0E7E3E3158A04AA282BD9762B7FEF5D3(AT)Andrewlaptop>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
AMSAT-NA is again supporting the 51st Jamboree on the Air (JOTA) Scouting
event by dedicating AO-51 operation to the event. For October 18th and 19th,
AO-51 will be configured as a single channel V/U repeater, and all users are
requested to standby for JOTA stations. Please limit QSOs to those between
or involving at least one JOTA station during this weekend. The frequencies
used for this weekend will be 145.880 FM uplink, and 435.300 FM downlink, no
PL tone required. The mode change should occur at ~00:00 UTC on the 18th
(Friday evening in the US) and run for approximately 48 hours.
I'd like to wish the Scouts good luck operating via the AO-51 satellite for
the event, and would like to encourage reports to be sent to the AMSAT-BB or
directly to me at ko4ma(AT)amsat.org. Photo files up to 5 Mb total are also
welcome to my address for possible inclusion in an upcoming AMSAT Journal
article.
73, Drew KO4MA
AMSAT-NA VP Operations
------------------------------
Message: 5
Date: Mon, 13 Oct 2008 17:28:43 +0100
From: Gordon JC Pearce MM3YEQ <gordonjcp(AT)gjcp.net>
Subject: [amsat-bb] Re: ARISS images
To: "Ransom, Kenneth G. (JSC-OC)[BAR]" <kenneth.g.ransom(AT)nasa.gov>
Cc: amsat-bb(AT)amsat.org
Message-ID: <48F3773B.10907(AT)gjcp.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Ransom, Kenneth G. (JSC-OC)[BAR] wrote:
> Yesterday's tests were on a limited scale. The full operation is not
expected to start up until Garriott is aboard on Oct 14.
>
Ah. I'm doing it wrong then ;-)
Thanks
Gordon
------------------------------
Message: 6
Date: Mon, 13 Oct 2008 09:30:00 -0700 (PDT)
From: Jeff Wandling W7BRS <jw(AT)w7brs.com>
Subject: [amsat-bb] manual keplerian calculations
To: amsat-bb(AT)amsat.org
Message-ID: <alpine.DEB.0.82.0810130857160.21667(AT)almond.he.net>
Content-Type: text/plain; charset="us-ascii"
Yes, I'm that sick.
I'm working on solving the predicion problem with a pencil and paper.
I've taken quite a bit of calculus, but that was quite some time ago.
Please reply directly. I'll make sure your fine words get back to the
list once the details are sorted out. I'd appreciate direct email replies
and I'll summarize to the list.
I have tracking software, I don't need to track via pencil and paper, I
just want to know how to do it by hand.
I'm refering to the ARRL book AMatuer Satellite Handbook (Davidoff)
I'm starting with the Keplerian data for AO-7 from Keplerian Bulletin 78,
ARLK078.
The epoch time is Oct 10, 2008 at 15:45:01.72Z
I attached the kep file for AO-7 for reference.
Any reference to values is about AO-7 from that Keplerian Update.
Here are my questions:
First to get the terms and understanding correct -- the Mean Anomoly is
listed as 320.9603 deg.
Is this the value of E that is used on page 12-4 to 12-5, and I quote:
"In an eliptical orbit, time from perigree, t is given by:
t = ( T / 2pi) * (E - e *sin(E)) [ eq 12.10 ]
where the angle E, known as the eccentric anomaly, is defined by the
associated equations:
E = 2 * arctan( sqrt( (1-e)/(1+e)) * tan ( (theta)/2 ) + (360deg * n)
n = 0 when -pi <= theta <= pi
or 1 when pi < theta <= (3pi)"
OK, so it says E (the eccentric anomaly) is a function of theta and
eccentricity.
Eccentricy of the orbit is in the Keps.
Let's just assume I'm trying to compute the lat/long of AO-7 at the epoch.
Is the RAAN in the Keps the longitude of the satellite at the epoch?
Is the mean anomaly the longitude of the satellite at the epoch?
I need the value of E to compute the value of t for this reason:
(skip ahead to page 12-18 from the Handbook mentioned above)
Finding latitude of the satellite, phi, at perigree is:
phi(p) = arcsin( sin(i) * sin(w) )
where i = inclination, w = angle between the ascending node and perigree.
Using equation 12.23, to find that latitude of the SSP:
phi(t) = arcsin ( sin(i) * sin( phi(t) + w) ) [Eq. 12.23 ]
Is that a misprint? the value of phi(t) depends on phi(t) ?
The gap here I'm trying to understand is, computing t (the elapsed time
since the ascending node) so I can plug it into the formula for latitude
[ phi as a function of t, phi(t) ]
Summary of questions:
Which data from the kep do I use to compute t based on equation 12.10
What does RAAN and Mean Anomaly mean at the Epoch?
Is the bird at latitude zero at epoch?
Computing a from Keplers laws, a = 31.25 * T^(2/3).
Is this T the Anomalistic Period?
Using that value of a, and eccentricity e, I can compute
w_dot = 4.97 * (Req/a)^(3.5) * (5 * cos^2(i) -1)/ ((1-e^2)^2) [eq 12.13a]
How does w_dot relate to ang of apogee from the kep data?
Thanks,
-jeff
W7BRS
ps. Again, reply directly -- this sort of question can make enough spam on
the DL to last you through Festivus.
-------------- next part --------------
SB KEP (AT) ARL $ARLK078
ARLK078 Keplerian data
ZCZC SK78
QST de W1AW
Keplerian Bulletin 78 ARLK078
>From ARRL Headquarters
Newington, CT October 10, 2008
To all radio amateurs
SB KEP ARL ARLK078
ARLK078 Keplerian data
Special thanks to AMSAT-NA (AMSAT.ORG) for the following Keplerian
data.
Decode 2-line elsets with the following key:
1 AAAAAU 00 0 0 BBBBB.BBBBBBBB .CCCCCCCC 00000-0 00000-0 0 DDDZ
2 AAAAA EEE.EEEE FFF.FFFF GGGGGGG HHH.HHHH III.IIII JJ.JJJJJJJJKKKKKZ
KEY: A-CATALOGNUM B-EPOCHTIME C-DECAY D-ELSETNUM E-INCLINATION F-RAAN
G-ECCENTRICITY H-ARGPERIGEE I-MNANOM J-MNMOTION K-ORBITNUM Z-CHECKSUM
AO-07
1 07530U 74089B 08283.65627308 -.00000027 00000-0 10000-3 0 2976
2 07530 101.4568 311.2861 0012054 039.2337 320.9603 12.53574392551323
Keplerian bulletins are transmitted twice weekly from W1AW. The
next scheduled transmission of these data will be Tuesday, October
14, 2008, at 2230z on Baudot and AMTOR.
NNNN
/EX
------------------------------
Message: 7
Date: Mon, 13 Oct 2008 18:38:06 +0200
From: "Simon \(HB9DRV\)" <simon(AT)hb9drv.ch>
Subject: [amsat-bb] Re: manual keplerian calculations
To: "Jeff Wandling W7BRS" <jw(AT)w7brs.com>, <amsat-bb(AT)amsat.org>
Message-ID: <EEC85C0A89F84A9497313D791D041CB5(AT)doubletrouble>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
----- Original Message -----
From: "Jeff Wandling W7BRS" <jw(AT)w7brs.com>
>
> ps. Again, reply directly -- this sort of question can make enough spam on
> the DL to last you through Festivus.
>
A very good starting point is Dr Kelso's work on http://celestrak.com/
And there's plenty (!) of C++ code out there which implements the
algorithms, so (worst case) you could figure things from the code.
Simon Brown, HB9DRV
www.ham-radio-deluxe.com
------------------------------
Message: 8
Date: Mon, 13 Oct 2008 10:14:19 -0700
From: cathrynham <cathrynm(AT)junglevision.com>
Subject: [amsat-bb] Re: manual keplerian calculations
Cc: amsat-bb(AT)amsat.org
Message-ID: <48F381EB.40606(AT)junglevision.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Simon (HB9DRV) wrote:
> ----- Original Message -----
> From: "Jeff Wandling W7BRS" <jw(AT)w7brs.com>
>
>> ps. Again, reply directly -- this sort of question can make enough spam on
>> the DL to last you through Festivus.
>>
>>
>
> A very good starting point is Dr Kelso's work on http://celestrak.com/
>
> And there's plenty (!) of C++ code out there which implements the
> algorithms, so (worst case) you could figure things from the code.
>
Bit of a digression, but you know what we need, one of these days,
is an open source code library for satellite tracking -- ideally
cross-platform for both *nix/Windows. This is something that
would get use outside of the amateur community.
------------------------------
Message: 9
Date: Mon, 13 Oct 2008 19:04:13 +0100
From: Gordon JC Pearce MM3YEQ <gordonjcp(AT)gjcp.net>
Subject: [amsat-bb] Re: manual keplerian calculations
To: amsat-bb(AT)amsat.org
Message-ID: <48F38D9D.5020703(AT)gjcp.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
cathrynham wrote:
> Simon (HB9DRV) wrote:
>> ----- Original Message -----
>> From: "Jeff Wandling W7BRS" <jw(AT)w7brs.com>
>>
>>> ps. Again, reply directly -- this sort of question can make enough spam on
>>> the DL to last you through Festivus.
>>>
>>>
>> A very good starting point is Dr Kelso's work on http://celestrak.com/
>>
>> And there's plenty (!) of C++ code out there which implements the
>> algorithms, so (worst case) you could figure things from the code.
>>
>
> Bit of a digression, but you know what we need, one of these days,
> is an open source code library for satellite tracking -- ideally
> cross-platform for both *nix/Windows. This is something that
> would get use outside of the amateur community.
>
What does gpredict use? It seems to work, so it would be a good start.
I wish I knew more about how to calculate the predictions...
Gordon
------------------------------
Message: 10
Date: Mon, 13 Oct 2008 20:24:58 +0200
From: "Simon \(HB9DRV\)" <simon(AT)hb9drv.ch>
Subject: [amsat-bb] Re: manual keplerian calculations
To: "cathrynham" <cathrynm(AT)junglevision.com>
Cc: amsat-bb(AT)amsat.org
Message-ID: <B0132D269A9D40E7B134834CA14B6B67(AT)doubletrouble>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
----- Original Message -----
From: "cathrynham" <cathrynm(AT)junglevision.com>
>
> Bit of a digression, but you know what we need, one of these days,
> is an open source code library for satellite tracking -- ideally
> cross-platform for both *nix/Windows. This is something that
> would get use outside of the amateur community.
>
The Windows DLL I use is available in source code, it's not really
Windows-specific as it's just number crunching. It handles satellites and
the Sun, Moon and maybe another planet.
To my surprise (!) I haven't put it on my new website, an error I can
correct :-)
Simon Brown, HB9DRV
www.ham-radio-deluxe.com
------------------------------
Message: 11
Date: Mon, 13 Oct 2008 20:29:42 +0200
From: Alexandru Csete <alexc(AT)phys.au.dk>
Subject: [amsat-bb] Re: manual keplerian calculations
To: Gordon JC Pearce MM3YEQ <gordonjcp(AT)gjcp.net>
Cc: amsat-bb(AT)amsat.org
Message-ID: <20081013202942.0736a2f5(AT)solaris>
Content-Type: text/plain; charset=US-ASCII
On Mon, 13 Oct 2008 19:04:13 +0100
Gordon JC Pearce MM3YEQ <gordonjcp(AT)gjcp.net> wrote:
> cathrynham wrote:
> > Simon (HB9DRV) wrote:
> >> ----- Original Message -----
> >> From: "Jeff Wandling W7BRS" <jw(AT)w7brs.com>
> >>
> >>> ps. Again, reply directly -- this sort of question can make
> >>> enough spam on the DL to last you through Festivus.
> >>>
> >>>
> >> A very good starting point is Dr Kelso's work on
> >> http://celestrak.com/
> >>
> >> And there's plenty (!) of C++ code out there which implements the
> >> algorithms, so (worst case) you could figure things from the code.
> >>
> >
> > Bit of a digression, but you know what we need, one of these days,
> > is an open source code library for satellite tracking -- ideally
> > cross-platform for both *nix/Windows. This is something that
> > would get use outside of the amateur community.
> >
>
> What does gpredict use? It seems to work, so it would be a good
> start. I wish I knew more about how to calculate the predictions...
Gpredict uses sgp4/sdp4 C-code by 5B4AZ, see
http://5b4az.chronos.org.uk/pages/norad.html , which is a
translation of Kelso's pascal code into ANSI C. I have made certain
modifications and optimisations to improve efficiency when tracking a
large number of satellites simultaneously but the algorithms are the
same. For gpredict it is built and linked as a static library but it
is only a matter of linker options to build a shared library (the
windows version does indeed use DLL). The code itself is re-entrant.
I have also seen C++ implementations, which might be more suitable for
C++ applications. I believe the tracking code from Ham Radio Deluxe is
also available as GPL; don't know about its portability though.
73
Alex OZ9AEC
------------------------------
Message: 12
Date: Mon, 13 Oct 2008 20:33:36 +0200
From: "Simon \(HB9DRV\)" <simon(AT)hb9drv.ch>
Subject: [amsat-bb] Re: manual keplerian calculations
To: "Alexandru Csete" <alexc(AT)phys.au.dk>, "Gordon JC Pearce MM3YEQ"
<gordonjcp(AT)gjcp.net>
Cc: amsat-bb(AT)amsat.org
Message-ID: <C4DB2582CB534CDD8CED442E5A021C49(AT)doubletrouble>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
I'm sure the HRD could be out in a nicely coded C++ library using GCC.
Simon Brown, HB9DRV
www.ham-radio-deluxe.com
----- Original Message -----
From: "Alexandru Csete" <alexc(AT)phys.au.dk>
>
> I have also seen C++ implementations, which might be more suitable for
> C++ applications. I believe the tracking code from Ham Radio Deluxe is
> also available as GPL; don't know about its portability though.
>
------------------------------
Message: 13
Date: Mon, 13 Oct 2008 20:50:27 +0200
From: "Simon \(HB9DRV\)" <simon(AT)hb9drv.ch>
Subject: [amsat-bb] Re: manual keplerian calculations
To: "Alexandru Csete" <alexc(AT)phys.au.dk>, "Gordon JC Pearce MM3YEQ"
<gordonjcp(AT)gjcp.net>
Cc: amsat-bb(AT)amsat.org
Message-ID: <5B7D4198DA574953852DA0F27242EB81(AT)doubletrouble>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
In English: I'm sure the HRD code could be compiled into a nice Linux
library.
Simon Brown, HB9DRV
www.ham-radio-deluxe.com
----- Original Message -----
From: "Simon (HB9DRV)" <simon(AT)hb9drv.ch>
> I'm sure the HRD could be out in a nicely coded C++ library using GCC.
------------------------------
_______________________________________________
Sent via amsat-bb(AT)amsat.org. 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 3, Issue 520
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