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Re: Satellite-to-Satellite communications



AMSAT-NA and AMSAT-DL will determine the exact orbits when they fire the
onboard rocket engines. They will both be Molniya orbits similar to AO-13.
No one has decided how to phase the orbits of the two and won't have to
until 2009. Since there are no station-keeping engines, the relationship may
change over time. For intersatellite communications it would be best to have
two earth stations linked via the Internet to maximize availability.

73,

John
KD6OZH

----- Original Message -----
From: "Dave Hartzell" <hartzell@gmail.com>
To: <amsat-bb@amsat.org>
Sent: Monday, January 09, 2006 04:05 UTC
Subject: Re: [amsat-bb] Satellite-to-Satellite communications


> Are the planned orbits of the two spacecraft different enough that a
> cross-link would increase ground coverage?
>
> And asking that question makes me wonder if the orbits are similar
> enough to even permit an economical cross-link, even for a few hours
> a day during several months...
>
> Thanks,
>
> Dave
> N0TGD
>
>
> On Jan 8, 2006, at 6:56 PM, John B. Stephensen wrote:
>
> > 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
> >>> ----
> >>> 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!
> >>> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> >> ----
> >> 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!
> >> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> > ----
> > 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!
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>
> Dave Hartzell
> hartzell@gmail.com
> ----
> 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!
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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