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CX2SA > SATDIG 11.10.11 21:04l 317 Lines 13804 Bytes #999 (0) @ WW
BID : AMSATBB6563
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Subj: AMSAT-BB-digest V6 563
Path: IZ3LSV<IK2XDE<PY1AYH<PY1AYH<CX2SA
Sent: 111011/1902Z @:CX2SA.LAV.URY.SA #:31916 [Minas] FBB7.00e $:AMSATBB6563
From: CX2SA@CX2SA.LAV.URY.SA
To : SATDIG@WW
Today's Topics:
1. Re: KickSat - a personal spacecraft of your own in space
(Zac Manchester)
2. WD9EWK @ Tucson AZ hamfest and post-hamfest activity, 22
October (Patrick STODDARD (WD9EWK/VA7EWK))
3. Re: Geostationary Satellites (Bob Bruninga)
4. Re: Geostationary Satellite (R Oler)
5. % in EM55 (wa4hfn@xxxxxxx.xxxx
----------------------------------------------------------------------
Message: 1
Date: Tue, 11 Oct 2011 13:06:11 -0400
From: Zac Manchester <fleet@xxxxxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: KickSat - a personal spacecraft of your own in
space
Message-ID:
<CAKkXDTV_44zdwHaf+VAKbKF8n04xEakaKs9qC6PyYL8pKOcoPA@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Hello All,
Sorry for taking so long to respond here on the AMSAT-BB - I know I've
spoken with some of you separately by email through kickstarter, but I
wanted to make sure I responded to everyone's concerns.
In response to Andreas' comments about wanting to use his own hardware
to listen to the Sprites, this is exactly the sort of thing I want to
encourage, and why I initially posted here. I posted a brief "Amateur
Radio Information" item in the FAQ on kickstarter with some of this
information, but I'll try to cover everything here.
The Sprites will all be on the same frequency in the 70 cm band, and
each will use a unique PRN spreading code so they can be identified.
The hardware you'll need to receive these signals will be a yagi,
rotator, LNA, and software defined radio (SDR) interface. We've been
using a USRP box from Ettus Research along with GNU Radio, but the
USRP is pretty expensive, so we're trying to make everything work with
the FUNCube dongle (http://www.funcubedongle.com/). To work with the
FUNCube, we have to make sure the signal bandwidth is < 80 kHz (it's
currently around 100 kHz). I'll be posting all the details of our
setup as we refine it, as well as all the code for the SDR. Even if
you don't sponsor a Sprite, it would be great to have more people on
the ground listening in. Everything we're doing will be documented,
open-sourced, and freely available online.
We will most definitely abide by all regulations and apply for
frequency coordination with the IARU. We haven't taken that step yet
because we have to actually be slotted for a specific launch first.
This is also why we don't know our exact frequency yet.
Please let me know if you have any additional questions.
Thanks,
Zac
------------------------------
Message: 2
Date: Tue, 11 Oct 2011 10:30:46 -0700 (PDT)
From: "Patrick STODDARD \(WD9EWK/VA7EWK\)" <amsat-bb@xxxxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] WD9EWK @ Tucson AZ hamfest and post-hamfest
activity, 22 October
Message-ID:
<1318354246.42878.YahooMailClassic@xxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=us-ascii
Hi!
The hamfest season out here in Arizona is about to start. I will be
at the Old Pueblo Radio Club's annual hamfest in Tucson AZ a week from
Saturday, on 22 October 2011. This is a week later than usual, since
this hamfest has normally taken place the same weekend as the Scouting
Jamboree on the Air event. The hamfest will be at the usual location
in Tucson, at the Kino Sports Complex along the north side of Ajo Way
at Forgeus Avenue, east of the I-10 freeway and the baseball stadium
(grid DM42me). The hamfest officially runs from 7am-noon (1400-1900
UTC), although people start showing up before sunrise and many leave
before noon.
During the hamfest, WD9EWK will be on whatever FM and SSB satellites
are available doing on-air demonstrations. On the SSB birds, I try
to park about 5-10 kHz above the center of the transponders, depending
on other activity and QRM/QRN. Please feel free to call WD9EWK during
those demonstrations and say "hello" to the crowds.
After the hamfest, I plan on driving either to the DM51bx/DM52ba or
DM52ax/DM53aa grid boundaries in southeastern Arizona to work some
passes on my way home. I have operated from both of these grid
boundaries earlier this year - DM51bx/DM52ba in early May, and
DM52ax/DM53aa in late March - and try to visit these locations when I
attend hamfests in southern Arizona. If you have a preference on which
boundary I should try to work from after the hamfest, please e-mail me
directly. I can't guarantee I will go to the spot you would prefer, but
it helps to know what people are interested in hearing on the birds.
As with the hamfest demonstrations, I am prepared to work both FM and
SSB from wherever I go out there.
As with my other trips away from the Phoenix area, there is no need
to send me a QSL request to get a WD9EWK QSL card for a hamfest QSO
or a QSO from one of those grid boundaries. Just e-mail me the QSO
details - if you're in the log, you'll get a card. QSOs will also
be uploaded to the Logbook of the World system as WD9EWK, including
the grid(s) and county for each QSO.
73!
Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
------------------------------
Message: 3
Date: Tue, 11 Oct 2011 13:41:37 -0400
From: "Bob Bruninga" <bruninga@xxxx.xxx>
To: "'Ken Ernandes'" <n2wwd@xxxxxxxxxx.xxx>
Cc: 'AMSAT-BB' <AMSAT-BB@xxxxx.xxx>
Subject: [amsat-bb] Re: Geostationary Satellites
Message-ID: <043001cc883d$06ddbf00$14993d00$@xxx>
Content-Type: text/plain; charset="us-ascii"
>> the risk of collision is more real than one might think.
> I would think the risk of collision is so tiny
> as to be effectively negligible.
I think it is, but when "negligible" incurs about a BILLION$$$ worth of
loss, it magnifies the risk.
> If we position our satellite halfway between two... "slots"
I think that is the problem. One has to stay there. GEO orbits are
impacted by the sun, moon and tides and solar wind. All GEO orbits drift*.
Hence 90% of the mass of these GEO birds are fuel for station keeping. And
that is where the risk comes from. As soon as a spacecraft loses fuel, or
command/control, or any other problem that causes it to no longer keep its
station, it becomes a drifting hazard, moving literally FOREVER along this
extremely narrow orbit, the same orbit that all of these other satellites
are in! It becomes a real hazard to them all.
That is why all nations now subscribe to the requirement that all GEO
spacecraft must have 10% reserve fuel to propel an aging satellite out to
the graveyard orbit. And this must be done before there is loss of
command/control.
> Is there no clever trick of orbit design
> that can be used to avoid collision?
Not and be geostationary. I think long term drift is the final state of any
GEO orbit. Though there are , I think, *two spots on the entire GEO orcit
which are stable.. but guess what. NO ONE WANTS them, because that is where
all the junk collects and that is where the chances of a collision with all
that junk is highest.
> We can even tolerate some long-term motion...
> Perhaps these extra freedoms would make it possible
> to design an orbit that's close enough to geosynchronous
> for our purposes, but far enough from the commercial orbits to be safe?
I'd guess that being in an orbit closer to earth would be best so that with
time we get further from the GEO arc. But closer in, moves faster and so
all we have to do is chose the DRIFT rate. Let it drift a full cycle once a
year, and the result is that any given country only sees it for 4 months a
year. No matter where we put it, it will be out of view to any one station
2/3rds of the time. But now that it is in its own special orbit, there wont
be any cheap rides to get there...
Our best bet is to piggy back on someone else's bird.
Oh, and it takes almost 10,000 times more power to hit a GEO bird at 22,500
miles away compared to hitting a LEO bird directly overhead (225 miles).
Just my 2 cents
Bob, Wb4APR
------------------------------
Message: 4
Date: Tue, 11 Oct 2011 12:02:07 -0500
From: R Oler <orbitjet@xxxxxxx.xxx>
To: <howied231@xxxxxxx.xxx>, Amsat BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Geostationary Satellite
Message-ID: <COL106-W63912E723F9DE9AD4C7118D6E20@xxx.xxx>
Content-Type: text/plain; charset="iso-8859-1"
I agree that the "best" hope for a GEO payload is a hosted one on a
commercial sat, but the odds of it happening are pretty thin.
The biggest obstacle to this is not station keeping fuel however. There are
few satellites that simply run out of station keeping fuel with all their
transponders working. What ages a satellite is that the transponders start
failing, the solar power system starts degrading...etc. It simply IS NOT
that they come up to the disposal fuel and thats it.
The biggest obstacle is integration of an amateur payload built by amateurs
into something that has to work or there is a lot of money lost and there is
no insurance recovery if something like an amateur payload caused the
failure...or even some sort of problem with the primary payload.
If AMSAT or anyone else could go for hosted payloads the best possible
approach to that is some of the new intermediate altitude comm systems that
are out there now looking for hosted payloads...
Robert G. Oler WB5MZO Life member AMSAT ARRL NARS
> From: howied231@xxxxxxx.xxx
> To: amsat-bb@xxxxx.xxx
> Date: Tue, 11 Oct 2011 10:01:20 -0400
> Subject: [amsat-bb] Re: Geostationary Satellite
>
>
> I agree with much of what Dan, N8GFV, says. Our best hope of a high
altitude satellite is probably a hosted payload on a GEO sat. To make that
viable we need to consider the entire mission. GEO satellite operators are a
for-profit business and every aspect of a commercial satellite has a dollar
value. The major items are spectrum, power and fuel. Since hams bring their
own spectrum, that is a no cost item for us. If we need to use satellite
power then we would need to pay the market rate for the percentage of the
total satellite resource used for the design lifetime of the satellite,
typically 15 years. If the payload can be disabled by the operator we may be
able to negotiate a pay as you go plan so that we don't have to pre-pay 15
years worth of power. Developing very power efficient transponder systems
will reduce our costs. Trading bandwidth for power by using digital
encoding, strong FEC, regenerative transponders with DSP signal enhancement
will all aid in the reduct!
io!
> n of the power required to close a link.
> The other big cost factor is fuel. As previously stated here, station
keeping is a critical element in GEO satellites and with the advances of
component technology, a satellites lifetime in orbit is determined primarily
by the amount of station keeping fuel it can carry. The more fuel, the
longer the satellite life, the more time the operator can use to recover
their investment and make money. Every ounce added to the satellite affects
the cost of the launch and possibly the amount of fuel that can be carried
on board. Whether this is the case or not, the added satellite weight WILL
add to the launch cost that we would have to pay.
> The good news is that the AMSAT community and the satellite operators have
common interests in making satellites less expensive and more efficient. By
building on the technology pioneered in ARISSAT-1 we MAY be able to get some
cooperation from a commercial operator to deploy a technology demonstration
package as a hosted payload. This might be more probable than one thinks.
Satellite operators are EXTREMELY conservative and don't deploy new
technology until it is thoroughly proven. The commercial satellite market is
running out of real estate. Many of the big operators are at over 80%
capacity. Since they are for-profit organizations, they are running out of
product quickly and will not be able to grow their business. All the major
operators are investing large amounts of money to promote a hosted payload
business where government and scientific users can bring their own bandwidth
to a transponder or payload on the operators platform. A low cost, high
performance, innovat!
iv!
> e payload COULD be a great advertising tool for a commercial operator.
The operator would get the payload for zero cost and could also get part of
the launch cost subsidized by AMSAT in return for a real world, open source
demonstration tool.
> If we build this payload along the lines of Tom Clark's C-C rider concept
with a 5 GHz up/ 3 GHz. down transponder we can probably even use the
satellites low gain telemetry antenna, further reducing payload costs.
> Sorry for the lengthy post but I have been thinking about this for a while
and this seemed like a good opportunity to finally put it in writing.
> HowieAB2S
> _______________________________________________
> 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: 5
Date: Tue, 11 Oct 2011 17:54:29 +0000 (UTC)
From: wa4hfn@xxxxxxx.xxx
To: AMSAT <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] % in EM55
Message-ID:
<1673241796.282358.1318355669533.JavaMail.root@xxxxxxx.xxxxxxxxxxx.xx.xxxx.xxx
xxxx.xxx>
Content-Type: text/plain; charset=utf-8
The 5 in em55 award info can be seen on QRZ lookup WA4NVM or WA4HFN .
Skeds are ok too.
Several donations to AMSAT have been made from this award Thank you
------------------------------
_______________________________________________
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 563
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