[amsat-bb] Re: Phase 4

Robert McGwier rwmcgwier at gmail.com
Tue Oct 30 18:25:54 PST 2007


Thanks for your question and your support as an AMSAT AC!

There will be essentially no squint angle problem.  Consider it to be a 
constant AO-40 apogee forever with the antennas always nadir pointing.

The following is the CURRENT plan (straw man) before we have had our 
first serious engineering meeting.  The "go ahead and tell the world" 
came from Intelsat five days before the symposium.  So factor that into 
both your thinking and your responses to questions.  Until then, we had 
little to say.   You can already see the impact of the world wide 
amateur distribution on this topic.  Having said that, it should be 
clear we have a lot of work to do.  The current plan is to take the 
Eagle payloads and adapt and modify them for this opportunity.  There 
will be a serious linear transponder and a serious digital transponder 
to support the AMSAT vision statement.  We are looking to give amateur 
radio in the U.S area its best ever tool to support those activities 
that keep our bands in our possession: EMCOMM.  This will also be the 
reason and source for much of our funding.

So I would say U/L up and V/S down for linear and C up and S2 down for 
digital.  The S2 down will  have extremely low power flux density to 
meet the "noninterference" requirement that should allow wide operation.

We do not know which bird(s) we will be on, so we do not yet know the 

Look here for the Intelsat map.  They circumnavigate the equatorial belt 
to the point you could almost walk across!


Click on the flash map if you have flash installed.  It is pretty neat.

There is nothing definitive we can say, we are just too new to this and 
are just getting ourselves fully engaged in the process.


k0vty at juno.com wrote:
> Hi Robert (N4HY)
> I have been reading all the info on the BB about what appears to be a Geo
> syncronous amateur system supported by a commercial bird.
> Obviously you and others have done much work to understand this scheme
> in order to develop support for it.
> My problem is I do not have enough to really handle this issue as a Amsat
> Coordinator and was not able to attend the symposium.
> Being an uninformed Amsat Coordinator is not healthy for Amsat.
> Is a system level proposal for this new Phase 4 going to be provided with
> sufficient numbers to allow membership evaluation before any impact on
> the Eagle system effort is considered acceptable.
> A question that needs an answer as I have already been asked.
> Will an analysis of the effects on the HEO DXCC desires of the membership
> as to the effect of a stationary fixed aperture antenna pattern in Geo
> versus a moving satellite location fixed aperture antenna system not in
> Geo.
> To include the need to use high squint angles and power levels required
> on both
> ends of this sort of  link budget.
> Sorry I did not attend the symposium.
> Joe Murray K0VTY
> Amsat # 860
> Amsat area Coordinator NE

AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
“An optimist may see a light where there is none, but why
must the pessimist always run to blow it out?” Descartes

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