[amsat-bb] Re: Eagle and emergency traffic (was Re: Galileointerference on L band)

Robert McGwier rwmcgwier at comcast.net
Sat Sep 23 23:56:18 PDT 2006

George Henry wrote:
> ----- Original Message ----- 
> From: "John B. Stephensen" <kd6ozh at comcast.net>
> To: "George Henry" <ka3hsw at earthlink.net>; "amsat bb" <amsat-bb at amsat.org>
> Sent: Saturday, September 23, 2006 5:08 PM
> Subject: Re: [amsat-bb] Eagle and emergency traffic (was Re: 
> Galileointerference on L band)
>> Why would it be available for only short periods? Eagle is a HEO.
>> 73,
>> John
> I said RELATIVELY short periods...  what is the maximum time that the 
> proposed data transponder will be available to a given ground station, with 
> favorable squint angles, on any given orbit?  What is the TOTAL, cumulative 
> access time per day?  From the perspective of an emergency manager or 
> disaster team captain, it is certain to seem small when 24/7 service is 
> available from other sources, particularly sources that they have already 
> invested in.  And since the design team is looking into their crystal ball 
> at what the state of things will be 5 years down the road at launch, surely 
> they have seen that the entire internet access landscape is sure to have 
> undergone a sea change by then?  (Bill Gates sure seems certain of that...)
> I repeat:  if the design team has anything from the NGOs to bolster the 
> claim that they (NGOs) "need it for emergency data communications", then 
> let's see it.

I don't believe anyone said we had a directive to provide a service.    
How could we have such a directive when we don't have the satellite 
designed yet?  What NGO or government agency do you know would empower 
us to do something or even ask based on a hope we get our facility 
launched in the next half decade?   I wouldn't go see them about using 
us in their planning until such time as the facility was actually 
available.   That does not make it a sin or a fault to hope to provide 
that facility and to think about what it would take to make it 
possible.  I certainly don't hang my head in shame because I have those 
thoughts. In fact,  I am kind of proud of us for taking it into 

Eagle is being designed to provide long term access per bird as compared 
to previous and planned P3 birds.  The advanced communications package 
is being designed around the use of phased arrays.  The phased array 
design is targeting 70% of the orbit to be usable per bird.  If we 
choose to stay in a 12 hour orbit,  that is 8-ish hours per orbit.   The 
only way this can be made to work in a usable fashion, providing voice, 
conferencing, data/file transfer is the use of digital signaling.  
Admittedly, no ground station will see every orbit since we are also 
aiming for an equatorial orbit.   We need more than one bird. 


AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
"You see, wire telegraph is a kind of a very, very long cat.
You pull his tail in New York and his head is meowing in Los
Angeles. Do you understand this? And radio operates exactly
the same way: you send signals here, they receive them there.
The only difference is that there is no cat." - Einstein

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