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CX2SA > SATDIG 08.02.09 00:06l 603 Lines 22118 Bytes #999 (0) @ WW
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Today's Topics:
1. Re: HEO naivete (Art McBride)
2. RE: Re: HEO na?vet? (Robert Bruninga)
3. Re: Was HEO naivete; now GEO rideshare frequency choice, etc.
(Art McBride)
4. RE: Re: HEO na?vet? (Rocky Jones)
5. Re: Re: HEO na?vet? (Michael Heim)
6. Re: Was HEO naivete; now GEO rideshare frequency choice, etc.
(Rocky Jones)
7. tracking tools (Greg Wycoff)
----------------------------------------------------------------------
Message: 1
Date: Sat, 7 Feb 2009 10:12:20 -0800
From: "Art McBride" <kc6uqh@xxx.xxx>
Subject: [amsat-bb] Re: HEO naivete
To: "'James Duffey'" <JamesDuffey@xxxxxxx.xxx>
Cc: 'AMSAT BB' <amsat-bb@xxxxx.xxx>, 'Mike and Paula Herr'
<herr@xxxxxxxx.xxx>
Message-ID: <482BFB96D9C04BA5996CB48E3046F119@xxxxxx>
Content-Type: text/plain; charset="us-ascii"
James,
Sorry I slipped a decimal point but 0.2% is still 49.81% short of a
majority!
Art, KC6UQH
-----Original Message-----
From: James Duffey [mailto:JamesDuffey@xxxxxxx.xxxx
Sent: Saturday, February 07, 2009 8:05 AM
To: kc6uqh@xxx.xxx
Cc: James Duffey; Andrew Glasbrenner; Mike and Paula Herr; AMSAT BB
Subject: Re: [amsat-bb] HEO naivete
On Feb 6, 2009, at 11:44 PM, Art McBride wrote:
>
> Amateur radio operators are .02 % of the US population. Boy do we have
> influence!
>
Art's math needs some revision. There are about 600,000 hams in the
US. The US population is 300,000,000. Thus, 0.2% of the US population
are hams, not 0.02%.
Interestingly enough, this error is roughly the same as the ratio of
the height of an LEO to the height of an HEO.:^)= - Duffey
--
KK6MC
James Duffey
Cedar Crest NM
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------------------------------
Message: 2
Date: Sat, 7 Feb 2009 13:15:15 -0500
From: "Robert Bruninga" <bruninga@xxxx.xxx>
Subject: RE: [amsat-bb] Re: HEO na?vet?
To: <amsat-bb@xxxxx.xxx>
Message-ID: <AE6441E2B8034B21AA4F07DB14827A74@xxxxx.xxxx.xxx>
Content-Type: text/plain; charset="iso-8859-1"
>> The microwave thing always gets me though.
>> If the antennas are too big how come they
>> can get them on cube sats?
>
> CubeSats buzz around 180 miles over your
> head. At apogee, AO-13 was 23,000 miles
> from the ground.
And every radio amateur knows that it takes 4 times the power to
double the distance. So lets do the math. The difference in
*power* (antenna gain or whatever) to go from 200 miles LEO to
20,000 miles HEO is 2x2x2x2x2x2x1.6 in distnace or 4x4x4x4x4x4x3
or 10,000 times more power. In dB that is 6+6+6+6+6+6+4 dB or
about 40 dB. That means to get the same performance from HEO as
you get from a 1 Watt cubesat, you would need a 10,000 watt HEO
satellite.
But everyone also knows that satelites in 200 mile orbits spend
95% of their time from 500 to 2000 miles away lower on the
horizon. So the real difference is about say 33 dB maybe.
Usually we make HEO's work by getting 13 dB more power on the
satelilte (20 watts) 13 dB more power in the ground station
antenna, and maybe 7 dB more power in the sateliite downlink
antenna to make up for the 33dB or so greater distance.
Hence, HEO's need more power and big antennas on the satellite
and on the ground to work.
Bob, Wb4APR
------------------------------
Message: 3
Date: Sat, 7 Feb 2009 10:25:13 -0800
From: "Art McBride" <kc6uqh@xxx.xxx>
Subject: [amsat-bb] Re: Was HEO naivete; now GEO rideshare frequency
choice, etc.
To: "'Andrew Glasbrenner'" <glasbrenner@xxxxxxxxxx.xxx>, "'Rocky
Jones'" <orbitjet@xxxxxxx.xxx>, <w7lrd@xxxxxxx.xxx>, "'Amsat BB'"
<amsat-bb@xxxxx.xxx>
Cc: k3io@xxxxx.xxx
Message-ID: <BE9870F4F87E4A3993DD3EA50E8C001A@xxxxxx>
Content-Type: text/plain; charset="us-ascii"
With the political climate focused on jump starting the economy AMSAT should
work on a bailout ride for three HEO's, it's our kids money anyway!
Art, KC6UQH
-----Original Message-----
From: amsat-bb-bounces@xxxxx.xxx [mailto:amsat-bb-bounces@xxxxx.xxxx On
Behalf Of Andrew Glasbrenner
Sent: Saturday, February 07, 2009 9:38 AM
To: Rocky Jones; w7lrd@xxxxxxx.xxxx Amsat BB
Cc: k3io@xxxxx.xxx
Subject: [amsat-bb] Was HEO naivete;now GEO rideshare frequency choice, etc.
Bear with me as I try to clear up some misunderstanding about the
frequencies proposed for the GEO rideshare proposal. Hopefully Tom will
chime in here if and when I get something wrong; the proposal was his. As he
will probably tell you I was not his biggest supporter, but I think I've
come to understand why he made the choices he did. Keep in mind Tom's
proposal was just that, a proposal. Even he described it as a strawman
proposal.
There were a few different driving factors for this rideshare proposal. One
was the real estate available to us. We were offered a few boxy shaped areas
on the order of 12 to 18 inches on a side, the exact numbers escape me.
There would not have been much room for any sort of gain antenna for lower
frequencies, which unlike a cubesat, is really required at GEO altitudes and
amateur array sizes and typical power levels.
A second driving factor was funding. The initial suggested costs rapidly
grew to the point where this could not be accomplished strictly with amateur
funding, and we would have to solicit support from a governmental agency. We
would need a carrot for them to justify their funding, and that carrot was
emergency communications. The usefulness of such a system would require that
some decent amount of data be moved, and the required groundstation be small
and portable. An additional factor was the assumption that a ground station
using a small dish might also be useful for allowing hams in CC&R restricted
homes to participate on the sly outside of times of emergencies, by
masqerading as a TVRO dish as protected by FCC rule. (I personally had
reservations about this last line line of thinking regarding CC&Rs and the
TVRO exemptions).
There was also concern about interference to the primary spacecraft
frequencies, so the frequencies suggested were driven by what were hoped
would provide the least amount of possible interference to our landlords on
the satellite. Any interference at all would probably mean the end of our
mission.
As discussions progressed, there was some dissension among the BOD about the
frequencies chosen and the digital versus analog issues. Tom revised the
microwave system design to include both analog and digital modes. More link
analysis by others showed we could possibly go as low as 1.2 GHz and 435 MHz
for some services, but not at the same ground station size or the same
amount of bandwidth. These would likely have been analog systems, and their
inclusion may have been to the detriment of the microwave services that were
the carrot -that would pay for the launch-. Frequency selection was a big
catch-22.
Warning, more of my personal opinion ahead! In the end, it was a mostly moot
exercise because our landlord found another tenant for the immediate launch
who could pay the rent out of pocket. We may have additional opportunities
down the road, but the price tag will not likely ever get smaller. We
realized we have not much experience at going to government for financial
supoort, and that will have to be addressed before we try this again. We'll
need someone who knows how to write grant proposals to help us. If this is
you, please directly contact one or all of the senior leadership. I
personally am also not sure we have the manpower to commit to a large
short-fuse project.
Some good things did come out of this exercise. As a result AMSAT has an
engineering task force who is now coordinating the creation and cataloging
of individual modules that can be used to seize very short term
opportunities for flight. Personally, I envision us placing secondary
packages on larger, funded satellites, as the best way to orbit in the
future. A transponder on a GPS satellite, or a FM repeater on a university
nanosat, or a digipeater on a cubesat...this I believe is our widest and
most direct path to the orbit. We should also expand on leveraging our
capabilities as a distributed telemetry collection service as a means to
acquire space for secondary packages for our own use. Delfi C-3 is a good
analog of what our future with the cubesat community should look like.
Meanwhile, there are several of us who are very active in trying to identify
these flight opportunities, but we could use more help. We have a few things
in the works, one of which is not LEO, but we are not at a point were we
could discuss them openly. ( A favorite saying of mine, first rule of fight
club is we don't talk about fight club, at least until we think it's safe)
We have many members that work in aerospace and if you are one of them and
you think there may be an opportunity to fly a package on one of your
projects, PLEASE contact myself or one of our other officers directly.
To the other BOD members and involved parties, I apologize if you think I
have misrepresented anything; please feel free to offer corrections directly
to the group.
73, Drew KO4MA
AMSAT-NA VP Operations and Director
_______________________________________________
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
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http://www.eset.com
------------------------------
Message: 4
Date: Sat, 7 Feb 2009 12:38:25 -0600
From: Rocky Jones <orbitjet@xxxxxxx.xxx>
Subject: RE: [amsat-bb] Re: HEO na?vet?
To: <gary_mayfield@xxxxxxx.xxx>, Amsat BB <amsat-bb@xxxxx.xxx>
Message-ID: <COL106-W344618285D3DF10C56757D6BE0@xxx.xxx>
Content-Type: text/plain; charset="Windows-1252"
Joe...Thanks for your comments.
My thoughts are similar but oriented along three lines
1. The amateur satellite population does not increase because of a couple of
reasons...not the least of which is a) no stable supply of satellites which b)
breeds no real stable supply of equipment which is obtainable and affordable
and c) since the numbers do not increase the funding pool doesnt increase.
2. None of this is going to get better as long as the projects done do not
keep those three things in mind. HEO, LEO, or whatever doesnt matter all that
much IF the satellite cannot generate the interest needed to sustain and grow
the population of hams on the bird...and that is linked (sounds like number 1
again) to the availability of equipment.
3. Many of the concepts floated dont address these issues. I for the life of
me have not figured out why the Europeans are working on a amateur radio
satellite to go to Mars...if they can get funding OK but how many "earth"
based hams are going to do anything meaningful with that... The stuff in the
latest journal is "nice" but is to be kind "vapor ware"...
I know that there are launch issues/cost etc etc...
but well maybe there is something I dont know...but if say SpaceX came to the
community "monday" and said "free ride on the Falcon 9...that might go this
summer.
Is there 'anything' to put up?
I dont think that the "orbit" is the problem.
Robert WB5MZO
> From: gary_mayfield@xxxxxxx.xxx
> To: amsat-bb@xxxxx.xxx
> Subject: RE: [amsat-bb] Re: HEO na?vet?
> Date: Sat, 7 Feb 2009 09:50:24 -0600
>
> My observations...
>
> I miss the HEOs too, and I believe our AMSAT-DL friends have an HEO
> basically waiting in the closet if a ride were to show (I know that's an
> over-simplification).
>
> I think a phase IV shared space satellite would/could be a great boon to
> emergency communications! And our public relations! But I fear it would be
> about as much fun to work as dialing my cell phone, no tracking, no Doppler,
> 100% predictable propagation. Okay, more reliable than my cell phone.
>
> The microwave thing always gets me though. If the antennas are too big how
> come they can get them on cube sats? I know the correct statement is
> high-gain antennas are too big. The problem is gain antennas need some
> pointing mechanism (complicated and expensive) and they need to be pointed
> no matter what band they are designed for. When using omni antennas the
> lower frequency will yield higher performance due to lower path loss....
>
> The bottom line is to keep building what ever we can get up there, and make
> sensible use of reasonable frequencies. I'm still glad AMSAT-NA built and
> orbited AO-51 as opposed to dumping all of our resources in Eagle which I
> believe would still be on the ground anyway.
>
> 73,
> Joe kk0sd
>
>
> At 04:28 PM 2/6/2009, Rocky Jones wrote:
>
_________________________________________________________________
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------------------------------
Message: 5
Date: Sat, 7 Feb 2009 11:07:40 -0800 (PST)
From: Michael Heim <kd0ar@xxxxxxxxx.xxx>
Subject: Re: [amsat-bb] Re: HEO na?vet?
To: amsat-bb@xxxxx.xxxx Jeff Davis <ke9vee@xxxxx.xxx>
Message-ID: <430732.51095.qm@xxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=iso-8859-1
I usually tend to keep quiet during arguements such as this, but I need to
chime in on this one.
I live in a location that frowns upon antennas. I was able to put up a mode
V/u as well as S band antenna to get me on AO-51. This antenna has 3 ele on
2m, 6 ele on 70 cm, and the S band antenna is a 18 inch long yagi.
This system is way too small for a GEO or HEO bird. I was on AO-10 + 13 when
they were up. My 2M was 22 ele crossed yagi, and a 10 turn 70 cm helix. Very
large antennas compared to what I'm using now.
I'm not certain, but I believe I would be able to receive an S band SSB signal
with my current S band receive setup from a geo sync orbit.
There is a law of physics that states that if the antenna size remains the
same and the frequency increases, the signal strength will also increase.
Notice I said antenna SIZE not GAIN, because as the frequency goes up and the
antenna remains the same size, the gain will overtake the increased path loss.
I understand the reason for having to use microwaves for rideshare birds.
Thing is, the microwaves give you a distinct advantage, and that is a stronger
signal and less noise. the cost for that? some new equipment.
I recently bought myself a new laptop. It wasnt a very high end unit, about
$600. I really didnt NEED it, but the same money would have bought me a new
microwave band and had money left over. Reason I didnt get the transverter?
lack of activity. If a satellite would have been launched, hey, guess what I
would have bought instead? yep, you guessed it... A new DX band!
Lets say 5760 is used on an upcoming bird. Ground station with a 19 inch dish
with a simple homebrew feed will have almost 30 dB of gain! thats 100 times
more signal than your 2 meter arrow, and the antenna is a lot smaller!
By the way, I hold VUCC on terrestrial 10 GHz, so I think I have some idea as
to what I'm talking about.
Michael Heim
ARS KD0AR
Amsat 36924
--- On Sat, 2/7/09, Jeff Davis <ke9vee@xxxxx.xxx> wrote:
> From: Jeff Davis <ke9vee@xxxxx.xxx>
> Subject: Re: [amsat-bb] Re: HEO na?vet?
> To: amsat-bb@xxxxx.xxx
> Date: Saturday, February 7, 2009, 11:10 AM
> On Sat, Feb 7, 2009 at 10:50 AM, Gary Joe Mayfield
> <gary_mayfield@xxxxxxx.xxx> wrote:
> > The microwave thing always gets me though. If the
> antennas are too big how
> > come they can get them on cube sats? I know the
> correct statement is
> > high-gain antennas are too big. The problem is gain
> antennas need some
> > pointing mechanism (complicated and expensive) and
> they need to be pointed
> > no matter what band they are designed for. When using
> omni antennas the
> > lower frequency will yield higher performance due to
> lower path loss....
>
> CubeSats buzz around 180 miles over your head. At apogee,
> AO-13 was
> 23,000 miles from the ground.
>
> That's why the gain antennas were needed and when you
> add up the power
> required for a transponder to handle lots of stations at
> the same
> time, then the link budgets and antenna sizes (for more
> gain) at
> higher frequencies begin to make a LOT more sense.
>
> The tightrope the developers walked was always how to
> deliver
> performance on frequencies that stubborn members demanded
> always be
> used. The S-mode stuff held much promise with AO-40. James
> Miller,
> G3RUH presented all the superior reasons for S-mode (the
> paper is
> still in the archives) but for a large percentage of
> members it was
> always "2 meters on the downlink or I will withhold
> funding".
>
> Just like those who raise a stink now whenever almost
> anything is
> proposed requiring more than a fifteen year old dual band
> handheld and
> an Arrow antenna...
>
> Sigh.
>
> As has been hinted around this thread, our problems are
> almost 100%
> self-inflicted. We have shot our toes off until we have
> none left to
> shoot. I don't blame the leadership -- this
> "club" contains some of
> the most stubborn individuals in all of hamdom. Perhaps if
> AMSAT can
> stick around long enough, the naysayers will all eventually
> die off
> and we can move forward with reality instead of dreamy-eyed
> reminiscing about days gone by and what might have been.
>
> Jeff, KE9V
> AMSAT-NA
> AMSAT-DL
> _______________________________________________
> 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: 6
Date: Sat, 7 Feb 2009 13:12:25 -0600
From: Rocky Jones <orbitjet@xxxxxxx.xxx>
Subject: [amsat-bb] Re: Was HEO naivete; now GEO rideshare frequency
choice, etc.
To: <glasbrenner@xxxxxxxxxx.xxx>, <w7lrd@xxxxxxx.xxx>, Amsat BB
<amsat-bb@xxxxx.xxx>
Cc: k3io@xxxxx.xxx
Message-ID: <COL106-W12C6FB00D42DBBE27A9865D6BE0@xxx.xxx>
Content-Type: text/plain; charset="Windows-1252"
> From: glasbrenner@xxxxxxxxxx.xxx
> To: orbitjet@xxxxxxx.xxxx w7lrd@xxxxxxx.xxxx amsat-bb@xxxxx.xxx
> CC: k3io@xxxxx.xxx
> Subject: Was HEO naivete; now GEO rideshare frequency choice, etc.
> Date: Sat, 7 Feb 2009 12:38:10 -0500
> 73, Drew KO4MA
> AMSAT-NA VP Operations and Director
Drew...thanks for your reply. It illustrates why you are one of the "good
eggs" in Amsat.
I guess that a couple of thoughts come to mind...ie ones I would have asked
had I been on the board discussion.
1. Do we have any reasonable expectation of government funding? The repeater
group that I belong to in Houston is in the process of getting a FEMA grant
based on the repeater/packet system performance in Ike...ie we stayed up while
the FEMA equipment colocated went dark. It has been "nip and tuck" and the
election of a congressman from our district who some of us participated in his
campaign has helped a great deal...but it isnt "all" that much money at least
in terms of what I suspect AMSAT was looking at.
2. even if we got the money and got the launch ...how does it change the
equation for the satellite community? It puts "equipment in the air" but
would the "unique" equipment required be a show stopper like the "spread
spectrum" satellite (PANSAT?) that was launched a few years ago.
3. I think that the "easy sat goal" is a "canard"...I think that it could be
as easy to talk on the birds as it is for me to type this letter to you...and
it wouldnt change the amateur satellite population all that much...but I do
think that the other end is a limiting factor. If hams have to buy some
"special box" that is the heart and soul of the station and has zero use
outside of the "bird"...then I dont think that is a measure for growth.
I am sure that there are a thousand reasons where my logic goes astray. But
what I see lacking in amateur satellite communications is a secure supply of
the "birds" that are accessable with commercially available gear.
Since you have been so kind, may I prevail for a question...?
If SpaceX granted us a ride on its Falcon 9 which might go this summer...is
there anything to put on it?
Robert WB5MZO
_________________________________________________________________
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------------------------------
Message: 7
Date: Sat, 7 Feb 2009 13:57:43 -0600
From: Greg Wycoff <gregwycoff@xxxxxxxxxxxxx.xxx>
Subject: [amsat-bb] tracking tools
To: amsat-bb@xxxxx.xxx
Message-ID: <06811C88-7953-441C-83CE-706D21D9137F@xxxxxxxxxxxxx.xxx>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
for those of you who have the ipod touch here is a couple of apps you
might want to check out.
"GoSatWatch" under reference
release date Dec 18 2008
"ISS" under utilities
release date jan 29 2009
Greg N0ZHE
------------------------------
_______________________________________________
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 4, Issue 61
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