[amsat-bb] Re: Double leo satellites

Robert Bruninga bruninga at usna.edu
Mon Sep 15 12:25:03 PDT 2008

Here is the link to our new Psat (dual APRS satellite

Bob, WB4APR 

> -----Original Message-----
> > Should it be possible to launch two Leo 
> > satellites...(satellite A) retransmitts 
> > what it hears to the other Leo satellite
> > (Satellite B)... I think in that way i 
> > could work NA every day?
> That is the intent of the APRS constellation
> of satellites.  All operating packet on 145.825.  
> We want to get as many of these satellties in 
> orbit as we can to not only provide continuity 
> of coveratge, but also dual-hop capabilities as 
> you suggest.
> APRS can inherently, auomatically, work via 
> dual hops, since it uses a generic path which 
> does not need to be configured for each 
> satellite callsign.
> That is also why the ISS moved to 145.825 
> a year or so ago, to be on the same channel, 
> with PCSAT-1,PCSAT2,ANDE, RAFT, and others.  
> There have been several instances of dual hop 
> packets.  The longest one recorded was from 
> Africa over the Atlantic to Maryland.  See:
> www.ew.usna.edu/~bruninga/pec/pc2ops.html
> Unfortunately, only ISS and PCSAT-1 remain 
> in orbit and PCSAT-1 only works under some 
> conditions, and ISS only works under others.  
> But if you can find them both working at the 
> same time, then dual hops are possible.
> You can watch the downlinks from these two 
> birds and look for activity and dual hops 
> just by looking through the on-line real-time 
> downlink logs:
> www.ariss.net for the ISS
> http://pcsat.aprs.org for the others
> You can see that ISS has been off the air 
> for 79 days except for a brief period 2 
> weeks ago.  And PCSAT-1 (W3ADO-1) continues 
> to limp along with some lucky packets during 
> northern hemisphere mid-day passes.
> Ideally, if we can get 6 to 10 small APRS 
> satellites on 145.825, we can provide near 
> continuous message/email/status capabiliy 
> from anywhere on Earth at any time.  That 
> is why I encourage all Universities making 
> CUBESATS or other small satellites to 
> include a 145.825 1200 baud packet link so 
> their satellites can be used in this 
> constellation after their primary mission is over..
> Our next Satellite from the Naval Academy 
> will actually be two-cubesats-at-once.  
> Both on 145.825 with APRS transponders.
> Please, if anyone is working with other 
> universities, see if they would consider 
> this global constellation mission for 
> their transponder...
> Bob, Wb4APR
> _______________________________________________
> Sent via AMSAT-BB at amsat.org.

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