[amsat-bb] Re: Galileo interference on L band

Rick Hambly (W2GPS) w2gps at cnssys.com
Fri Sep 22 04:55:33 PDT 2006


> ... we can't engineer for "unknown" future events. 

The L-band issues under discussion are not unknown. The impacts and
regulatory remedies for the Galileo community against Hams are uncertain,
knot unknown.

> It just bogs us down with worry that we 
> might not make the right "guess." 

No one is bogged down. The Eagle design team is weighing the issues
associated with each possible choice of uplinks and downlinks to maximize
the utility of Eagle to the largest community of users possible. The debates
on amsat-bb do not slow down the design process, although occasionally they
do provide interesting material for consideration.

> ... base decisions on the engineering facts 
> as we know them today ... and let the future 
> bring on whatever it has in store for us.

That would be an irresponsible thing for AMSAT leadership to allow, and the
Eagle project team knows it. To launch a high orbit satellite takes
resources that stretch the capability of the Ham community to the limit. We
must maximize the probability of a successful mission.

> If you can make arguments that L-Band won't work ...

We are getting way off track here. No one is saying L-band won't work, now
or in the future.  What we are saying is that there has been some evidence
to suggest that we could loose access to the band if "a" or "b" or "c"
happens.  This creates a concern that needs to be factored into the
evaluation of the alternatives for Eagle.

> But lets take this Galileo "cloud" 
> off the decision process.

I repeat that this would be an irresponsible decision. What needs to be done
is to evaluate this and other threats, which are largely out of our control,
and integrate the treats and their mitigation into our decision making

> I don't think many future AMSAT 
> communicators will fault you for not 
> being able to predict the future.

Really? I assure you that if we make a conscious decision to ignore an
important issue and we turned out to be wrong there would be a massive
campaign of criticism. 

I predict that there will be multiple L-band uplinks and an S-band downlink
on Eagle; they just won't be primary links. Whatever the outcome, the
decisions will be based on the best information available to the Eagle
project team, including inputs from the international community. They will
also be based on the need to attract new young Hams to satellites so our
future is secure.

Some of the people debating the issues on amsat-bb impress me as possibly
qualified to participate directly in AMSAT projects or in other responsible
roles.  We have openings and I encourage you to contact your AMSAT officers
and introduce yourself if you would like to volunteer you time and talent to
the advancement of Ham Radio. 


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