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Re: Satellite-to-Satellite communications



The characteristics of any digital transponder on Eagle haven't been
finalized. HEO digital communications are power limited because of the 35,000
km altitude so speeds may be closer to dial-up than DSL. HEOs are 45 times
further out than LEOs so communications requires 2000 times more radiated
power. The digital links used on LEOs are not very power efficient so some of
this loss can be recovered.

You could link analog transponders by repeating a portion of one downlink onto
another uplink. If the antennas used in the repeater have 6 dB more gain than
the users' antennas, there will be a dB or two of degradation, but it will
work.

73,

John
KD6OZH
  ----- Original Message -----
  From: Christensen, Eric
  To: Andrew Glasbrenner ; John B. Stephensen ; amsat-bb@amsat.org
  Sent: Monday, January 09, 2006 01:34 UTC
  Subject: RE: [amsat-bb] Satellite-to-Satellite communications


  Thinking it over with the good information that has been presented I agree
where if we are not in geosync orbit it would be difficult, but not
impossible, to track another HEO.  I think ground stations relaying to other
stations that have view of the other HEO is very workable.

  It could be very workable if everything is digital.  I'm still trying to
figure out the digital capabilities of the two new birds.  Maybe digital voice
as well???

  So maybe we should identify stations that have reliable satellite stations
and reliable Internet connectivity with 2Mb(???) connectivity or more.

  73s,
  Eric KF4OTN



-----------------------------------------------------------------------------
-

  From: Andrew Glasbrenner
  Sent: Sun 08-Jan-06 19:50
  To: John B. Stephensen; Christensen,Eric; amsat-bb@amsat.org
  Subject: Re: [amsat-bb] Satellite-to-Satellite communications


Not to mention how would you point the link antennas, and to where? We aren't
going to be in a fixed geosynch type orbit....

Now....ground based relays would be uber-cool. Imagine a 10-20 khz wide
transponder on the ground linking 2 HEOS on opposite sides of the planet.
You'd need a pretty fat pipe between groundstations, and a healthy uplink, but
wow...that would be an innovation (for us hams at least).

73, Drew KO4MA

-----Original Message-----
>From: "John B. Stephensen" <kd6ozh@comcast.net>
>Sent: Jan 8, 2006 7:26 PM
>To: "Christensen, Eric" <CHRISTENSENE@MAIL.ECU.EDU>, amsat-bb@amsat.org
>Subject: Re: [amsat-bb] Satellite-to-Satellite communications
>
>No intersatellite communications is planned. Intersatellite links would
>require just as much power as the satellite-to-ground links. The satellite
>would also have to be 3-axis stabilized to point the intersatellite
>antennas. The additional power and fuel would double or triple the weight
>and launch cost. The majority of AMSAT membership has been very clear that
>it wants simpler, cheaper HEO satellites so that more can be launched.
>
>When 2 or more HEO satellites are in orbit, Earth-based intersatellite links
>will be possible at a fraction of the cost of space-based links.
>
>73,
>
>John
>KD6OZH
>
>----- Original Message -----
>From: "Christensen, Eric" <CHRISTENSENE@MAIL.ECU.EDU>
>To: <amsat-bb@amsat.org>
>Sent: Sunday, January 08, 2006 18:05 UTC
>Subject: [amsat-bb] Satellite-to-Satellite communications
>
>
>> I was sitting here reading the Nov/Dec AMSAT Journal thinking about Eagle
>and
>> P3E when it hit me.  Are their any sat-to-sat circuits being built into
>these
>> satellites?  If we are going to have daily coverage of a HEO by 2009 and
>> continuous coverage by 2012 I think having the additional sat-to-sat
>circuits
>> would be very useful for providing worldwide coverage.
>>
>> Uncle Sam finally figured that out with the new MilStar sats.  Otherwise
>data
>> had to be relayed by ground stations between satellites to cover the area.
>>
>> Any ideas???
>>
>> 73s,
>> Eric KF4OTN
>> ----
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>----
>Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
>Not an AMSAT member? Join now to support the amateur satellite program!
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----
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