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Re: 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.





 >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 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!!!





 >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.





 >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!!!


 >  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!!!


 >  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???

 >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..



 >73 and Merry Christmas,
 >
 >John
 >KD6OZH

73, Bill N4XEO

E- Mail mailto: n4xeo@amsat.org
home page: http://www.qsl.net/n4xeo
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FPAC: http://www.qsl.net/fpac
ICQ: 19219163


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