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Re: Phase 4 satellite(s)?



See below for some comments.

73,

John
KD6OZH

----- Original Message -----
From: "n4xeo" <n4xeo@amsat.org>
To: "John Stephensen, KD6OZH" <kd6ozh@amsat.org>
Sent: Sunday, 24 December 2000 17:42 UTC
Subject: Re: [amsat-bb] Phase 4 satellite(s)?


 > I know that I'll get flamed for this reply, but I'm going to do it anyway.
 >
 >
 >
 > At 09:23 2000-12-24 +0000, you wrote:
 > >In looking at all the mail passing through this reflector recently it is
 > >obvious that the only type of satellite project for the future that will
 > >satisfy everyone is one that doesn't cost much, allows world-wide
 > >communication and is usable from a portable station with a fixed antenna.
 >
 > Why does it have to satisfy EVERYONE???? It only has to satisfy the
 > majority of the AMSAT "MEMBERS" and AO-40 "SATISFED" the majority of amsat
 > MEMBERS world wide.
 >
It doesn't really have to satisfy everyone to get funded. This was just a
comment on what appears on the AMSAT-BB. I donated $1000 to AO-40 last year
and built several transverters to use with it so I do support it.
 >
 > >This isn't technically feasible with one satellite. However, it is
feasible
 > >with a network of satellites that are interconnected. The number of
 > >satellites must be limited in order to fit AMSAT's budget.
 >
 > Since "you" are amsat, are you willing to get involved and start to work
on
 > this project??? If you get enough info and plans together, work it up to
 > present it to the amsat board. I'm sure the board would let you head it up
 > and run with it if it was workable
 >
I am just testing the waters to see if there is any support out there.
Submitting a proposal that only one person supports would be a waste of
time. It would take a phase 3D size team to implement this and it will take
two or three people to figure out how much this would cost, how long it
would take to build and put together a reasonable proposal.

What Phil Karn has been saying makes sense except for the fact that everyone
must buy new equipment immediately. A hybrid approach that supports existing
equipment might actually work. It's interesting that he hasn't commented on
my email.
 >
 > >  I read through
 > >some old AMSAT-NA Proceedings and see one possible solution.
 > >
 > >Perhaps AMSAT should be considering a marriage of satellite and Internet
 > >technology for voice communications similar to what is happening with
APRS.
 >
 >
 > I've seen the same thing with PACKET . once the internet came around
packet
 > went down hill in the USA. You have to remember that Amatuer radio is a
 > SERVICE that we are supposed to be giving. The hobby only comes into place
 > when we aren't needed for a emergency.
 > What is going to happen to the packet network in a emergency when the
phone
 > lines are down and no one had bothered to have RF links in place??
 > NOTHING!! our "service" would be useless.!!!
 >
 > Using your example above, what are we going to do when there is a
emergency
 > and the phone lines go down and we have NO INTERNET?? Or don't you care >
that it is a service first and hobby second??
 > We would have a bunch of leo birds up there that we wouldn't be able to
 > pass much traffic on because of their short pass time since the "internet"
 > link isn't there. I feel that the internet has it's place and so does
 > Amatuer radio, but not in the same box!!!
 >
My email may not be clear enough. The user can communicate with the
satellite directly via existing FM voice transceivers. The footprint of the
satellite covers the entire US so two or three ground stations could provide
redundant intersatellite links in case the phone lines go down and the
satellite would still be accessible within its footprint without the
intersatellite links.

So far none of our amateur satellites has been used to provide emergency
communications because they don't provide 24-hour coverage. We either need 3
phase 3 satellites or a constellation of lower orbit satellites to make them
useful for emergency communication. I think that the constellation would
provide more reliability and lower overall cost. However, the amount of
traffic that needs to go outside the disater area is generally small and is
easily handled by HF links. We can't easily justify the Amateur Satellite
Service on emergecy communication capabilities.

Amateur satellites can be better justified as educational tools if they
demonstrate new technologies that are useful outside the amateur radio
service. The system I proposed would do that.
 >
 > >Two articles in the 1997 Proceedings of the AMSAT-NA 15th space symposium
 > >provide some interesting information.
 > >
 > >Martin Davidoff, K2UBC, "Selecting Orbits for LEO Constellations: SSB/CW
 > >Communications"
 > >
 > >Daniel Schultz, N8FGV, "Digital Voice Modulation for a Future Generation
of
 > >Ham Satellites"
 > >
 > >K2UBC proposes multiple satellites in RS-15-like 2000 km polar orbits.
One
 > >satellite provides coverage of an entire continent wile it is overhead
and
 > >does not require the use of directional antennas.  It also provides
fairly
 > >long passes of 30 minutes or more and 4 satellites can provide as much
 > >access time per day as AO-13 did. More will provide even better access.
The
 > >cost of the project is also spread out over time as all satellites don't
 > >have to be launched at once.
 >
 > This would work, but it still wouldn't make a cheap ground station.
 >
The path loss numbers indicate that 15 watt FM transceivers could work the
satellite with omnidirectional antennas on 2 m and 70 cm. This would be less
expensive than an AO-40 ground station and make mobile operation practical.
 >
 > >To provide long distance communication, these satellites must be linked
even
 > >if they are not visible to each other. 20 ground stations, interconnected
 > >via the Internet, can provide this linking.
 >
 > Here we go with the internet again. It is funny that the only people that
 > keep talking about the internet are here in the USA. How would you propose
 > doing this same setup if there WASN'T "the internet" This I would be
 > interested in. Part of the thrill of the sats is making my station as best
 > as I can and not knowing who I will talk to. I can pick up the phone and
 > call anywhere in the world at any time. What ever happened to working DX
 > (calling a station that you don't know) and seeing if you can work them.
It
 > would take the "FUN" out of it if I can call anyone at any time and say
 > hi.. Kind of like picking up the phone!!!
 >
If the Internet didn't exist the linking would have to be accomplished with
leased telephone lines or there would have to be a lot more satellites so
that they could see each other directly more often. The Internet happens to
make the whole thing less expensive.
 >
 > >  Initially, coverage will not be
 > >continuous but intercontinental communication is provided in long enough
 > >intervals to permit a normal QSO.  Each satellite must have the capacity
to
 > >support at least 10 simultaneous conversations so we don't have the
problems
 > >associated with existing single-channel LEOs. The capacity and coverage
can
 > >be improved over time as there are more users of the satellite network.
 > >
 > >Since communications will be relayed through 2 satellites and the
Internet,
 > >it makes sense to use digital modulation for the uplinks from and
downlinks
 > >to the Internet.
 >
 > Would you be willing to put out the cash that it would take to setup and
 > maintain one of these ground stations so I would be able to just use my
 > HT  (ham shack on my belt) ?? I bet not!!!
 >
I'm willing to construct and maintain a ground station for intersatellite
links. The path loss figures indicate that your HT would be able to work the
satellite directly with a 20 watt amplifier and a 1/4-wave whip or with an
Arrow style antenna and without the amplifier.
 >
 > >  These would probably be TDMA links to minimize complexity,
 > >power requirements and signal degradation while relaying. User uplinks
and
 > >downlinks could support both analog FM and digital modes. N8FGV indicates
 > >that digital voice requires 2.4-13 KBPS or 5-25 kHz of spectrum per
 > >conversation so the Intenet bandwidth is not that expensive and we have
 > >enough spectrum available in the V, U, L and S bands for many of these
 > >satellites.
 >
 > When the phone lines are down or the internet isn't working, how will I be
 > able to use my ht here in the usa and talk around the world?? Will you
have
 > a backup plan using RF to keep the system going???
 >
Since we can have redundant intersatellite links the only event I can see
that would completely disrupt the system is a major war.
 >
 > >Does this sound like a useful project?
 >
 > Sounds like it would be useful to me if you had a way of connecting all
the
 > sats together WITHOUT using the internet and you would have someone set up
 > a ground station in my area so I would be able to just use my ht and not
 > have to do anything else.
 >
 > Bottom line is that no matter what we still need to have the ground
 > stations that have all the bells and whistles..
 >
We can eliminate the antenna rotators and go from a $1700 multimode
transceiver to a $800 dual band FM transceiver and still acheive the type of
communication that AO-13 provided. That would be a significant improvement.

I don't understand your opositon to the use of the Internet. I used to work
for a software company that made OSI communication software. OSI was wiped
out by the deregulation and promotion of the Internet so we had to swallow
our pride (mainly our president had to) and switch to making Internet
software. When we announced this at a sales meeting, our French distributor
stood up a and give a speech denouncing the Internet as an "American
military conspiracy." Within a year he was happily selling Internet software
because his customers liked it.
 >
 >
 > >73 and Merry Christmas,
 > >
 > >John
 > >KD6OZH
 >
 > 73, Bill N4XEO
 >
 > E- Mail mailto: n4xeo@amsat.org
 > home page: http://www.qsl.net/n4xeo
 > F.A.D.C.A.: http://www.fcrosby.com/fadca
 > FPAC: http://www.qsl.net/fpac
 > ICQ: 19219163
 >


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