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

Re: This Weekend in Minneapolis: Central States VHF Society Meeting


In upcoming journal articles and in Eaglepedia documents showing the 
detailed calculations upon which our statements are based,  we believe 
that Tom is being very kind indeed when he calls S band a sewer on the 
ground.   Furthermore,  as you can see from Tom's recent answers to the 
candidate questions,   we have to plan on a satellite that we believe 
cannot  be launched until 4+ years from now .   We cannot build a 
satellite where we hope, by some miracle, conditions return to those we 
had before AO-40 was launched or even those that prevailed at the end of 
its life.   Our computations,   which will be checked again,  and 
experiments done and supporting documentation will be provided to 
support,  show that we CANNOT PROVIDE sufficient ERP at the spacecraft 
for your old station to work as an S band weak signal downlink unless we 
restrict the usable orbit for S band to a small fraction of the orbit 
around apogee.  We fully understand that while S band may be usable by 
you as an individual,  but it is irresponsible of us to design a 
satellite where a small number of the current satellite users who live 
in rural areas can use the mode.  We need to design a spacecraft where 
we are attempting to use our crystal ball and current conditions to 
forecast the environment we believe the satellite will operate in for at 
least a decade.

We are all sorry for the demise of AO-40,  we look forward to P3E which 
itself may not be launched until 2008, but the following is a simple 
fact:   we are not duplicating P3E.  Eagle is a different mission 
entirely from an engineering and user standpoint.   We are not aiming 
for a 50+ degree inclined orbit.  We are attempting to provide for 
smaller antennas on the ground, provide for ENCOMM where it is legal, 
and designing user ground terminals that will work with the spacecraft 
when launched.   U/V is to be supported in as big a way as we can derive 
power and provide antenna gain.  Again, this is to minimize the required 
antenna on the ground.  As bad as 2 meters can be,  we believe it is not 
as bad as S band will be. 

Tom has not put in L band in this chart.  We do intend on having an L 
band receiver (or two) on board.  HOWEVER,    it is almost the unanimous 
feelings of the designers that this band is dead and we are simply 
watching its death throes.  The Galileo/GNSS constellation has already 
begun to eat into the L band allocation in Europe.  A single German TV 
repeater operator caused the German telecom administration to act with a 
sledge hammer against amateurs using L band.  

It is simply irresponsible of us to ignore these issues and we will 
not.  What we will do is work very hard indeed on stating our case with 
supporting documentation.

Let me say that nothing is as simple as "include a band and mode for a 
test".   We will not do engineering that way.   We are going to 
calculate and test and provide solid supportable instruments.

have seen are now history because of the cold hard calculations we did 
as engineered in a meeting in San Diego in late June.  What Tom and I 
are presenting,  what Rick and I presented to the ARRL board,  what you 
will see (much more fleshed out) in October is our current best opinion 
of what it will take the AMSAT engineering team to deliver on the 
mission statement the AMSAT board of directors has adopted.


Edward R. Cole wrote:
> At 01:01 AM 7/25/2006 -0400, Tom Clark, K3IO wrote:
>> This coming weekend, Bob McGwier (N4HY) and I are presenting a paper on
>> AMSAT's efforts on EAGLE and P3E at the Central States VHF Society
>> meeting in Minneapolis. The following words come from Bruce, W9FZ:
>> The 40th Annual Central States VHF Conference is just days away on July
> 28th and 29th in Bloomington, MN. It's being held at the Ramada Mall of
>> America (formerly The Thunderbird) and is just across the parking lot from
> the Mall of America. More details can be seen at http://www.csvhfs.org/.
>> Our paper contains a number of updates concerning EAGLE which you will
> read about in the next Journal. But for an advance view, you can see our
> CSVHFS paper, available as a ~3.9 MB PDF file at
> http://mysite.verizon.net/~w3iwi/EAGLE_CSVHFS.pdf
>> Sorry it's so long -- I hope you have a fast internet feed!
>> 73 de Tom, K3IO (ex W3IWI)
>> ----
> Tom,
> As I understand the conclusions from the CSVHFS presentation, Eagle is
> proposed with:
> Mode UV voice
> Mode UV text
> Mode S1C digital voice & video
> Mode S2 tlm beacon
> no mode L uplink
> no mode S downlink
> nothing stated about bands above C; what happened to mode UX or CX?
> Well, I'm not too happy with this result since I have invested in 60w
> mode-L and mode US & LS downlink equipment that will not have any use
> (except the beacon).  Of course glad that mode UV is supported.  I am not
> sure I see how this fits into replicating P3E.
> Another issue is that mw satellite sub-bands do not coincide with
> terrestrial sub-bands requiring additional equipment (e.g. my 2304, 3456,
> 5760, and 10368 equipment is not usable for satellite operation).
> I would suggest that Mode S (voice downlink) be included as a capablity to
> test.  If enough ERP is provided this will overcome terrestrial WiFi
> interference.  If not then we will have to surplus our mode-L and mode-S
> stuff (ouch!).
> I will be on a retirement budget by 2010 so the likelyhood of equiping for
> new satellite mw modes is slim.
> 73's,
> Ed - KL7UW  
> =========================================
> http://www.qsl.net/al7eb - BP40iq 
> 144-EME: FT-847, mgf-1801/1402, 4xM2-xpol-20, 170w
> 432-EME: FT-847, mgf-1402, 1x21-ele (18.6 dBi), 60w
> =========================================
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> Not an AMSAT member? Join now to support the amateur satellite program!
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
"An expert is a man who has made all the mistakes which can be
made in a very narrow field."  Niels Bohr
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org