[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: Eagle and emergency traffic (wasRe: Galileointerference on L band)



Points addressed below:

----- Original Message ----- 
From: "Robert McGwier" <rwmcgwier@comcast.net>
To: "George Henry" <ka3hsw@earthlink.net>
Cc: "amsat bb" <amsat-bb@amsat.org>
Sent: Sunday, September 24, 2006 1:56 AM
Subject: Re: [amsat-bb] Re: Eagle and emergency traffic (was Re: 
Galileointerference on L band)


<snip>

>> 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 consideration.
>

John's original message said, and I quote, "...The other impetus for 256 
kbps is that NGOs need it for emergency data communications."  When I see a 
statement like that, I expect to see hard and fast facts to back it up. 
John has since clarified that it is not an explicitly stated NEED, but 
rather a WANT that the NGOs have expressed "for years."  (What parent hasn't 
tried to make their child(ren) understand the difference between "need" and 
"want?")

Semantics aside, I pointed out that at least one of those NGOs (the American 
Red Cross) has poured tens, if not hundreds, of thousands of dollars into a 
commercial satellite internet solution, likely rendering our efforts to 
eventually meet that same want, obsolete.  By the time Eagle is bolted to 
the launch ring, satellite-connected laptops are likely to be an affordable 
reality for any disaster relief agency.

By all means, DO consider the possibilities, but don't lose sight of the 
realities in the process.


> 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.

Precisely the first point I tried to make:  anything less than 24/7 access 
is not likely to be viewed as very useful.  In a disaster, I'd love to be 
able to be on a satellite as I pull out of my driveway, like I can be on 40 
meters thru 70cm today.  The reality is that any bird that I *could* be on 
today, would be gone in 15 minutes or less.  Sadly, our current crop of 
satellites is ill-suited to emergency communications, and it will be at 
least 15 years before we can offer 24/7 coverage.  It doesn't mean that we 
shouldn't try:  it just means that we should recognize the possibility that 
disaster communications may never be our "niche".  In 15 years, other data 
communications technologies will, almost certainly, affordably eclipse what 
we have put into orbit.  And I don't know that AMSAT donors can ever afford 
the $$ to get ahead of that technology curve, which has VERY deep pockets 
driving it.

73,
George, KA3HSW


_______________________________________________
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb



AMSAT Top AMSAT Home