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Re: S band downlink on P3E



and a big hi, hi....Thanks Bob for telling it like it is.

On 9/8/06, Robert McGwier <rwmcgwier@comcast.net> wrote:
> Dave Guimont wrote:
> >
> >
> >
> >
> >             73, Dave wb6llo@amsat.org
> >                     Disagree: I learn....
> >
> >                Pulling for P3E...
> >
>
> As are many of us.  That said,  The S transmitter is not the primary
> mode of P3E.   The S band transmitter on P3E will be hooked to a dish.
> This dish will have a half power beam width which will limit the
> usefulness of the S band transmitter to those times of nadir pointing.
>
> The revelation of the results of our meeting, weeks before we could be
> ready to explain carefully that we are taking a system approach to the
> design of Eagle, is unfortunate.   Not because the conclusions are made
> public but because there is no context for the decision making process.
>
> We cannot build an AO-40 class spacecraft.   We do not have the
> personnel,  the facilities,  and we likely do not have sufficient talent
> that we can devote to such an enterprise.  We have talent in this
> organization and around the world.  But all of that talent leads a life
> outside of AMSAT.   As an engineering manager for AMSAT  it is my
> responsibility to make cold hard decisions based on personnel,
> calculation, advice,   studies,   equipment availability,  the
> availability of launches that we can use and on and on.
>
> The organization overreacted to AO-40.   It downsized Eagle
> considerably.   It set a goal of no motor.   It said "let's do digital"
> and "give them a whip antenna on two meters".  It did not say this in a
> crass manner but those were absolutely the conclusions of the
> organization policies when captured into engineering possibilities.
> It has literally taken me 11 months to ALMOST right the ship.    If the
> other people in the room will admit to it,  I single handedly saved the
> linear transponders in our current designs by
>
> a) picking the receiver designer
> b) picking the transmitter designer
> c) choosing SDX as the overall concept for the linear transponder
>
> EVERYONE is on board.  But do you think such things are done overnight?
> NO.  They are done with leadership and not by whining.  These decisions
> and their outcome led to a MUCH improved antenna system, power
> amplifier, and absolutely cutting edge efficiencies achievable for this
> transponder in our current plans.  It went from 25 kHz fed to a quarter
> wave monopole on the back side of the spacecraft  to serious antenna
> absolute eating valuable territory on the business side of the
> spacecraft and with bandwidth UP TO (but not necessarily) 100 kHz wide.
> The bandwidth will be determined by the TYPE of customers we wish to
> serve.  We do not want to serve only those who can transmit 10 kW
> EIRP.    We do want to support 1 KW EIRP SSB contacts.   We also want to
> support a text messaging service that will require a shortened dipole on
> 70cm and 2m which will not be limited to APRS users.
>
> The goals stated by the AMSAT board of directors for its next HEO
> spacecraft design as a follow on to P3E (besides supporting P3E in the
> interim) included aiding those people who live in CC&R (covenant
> restricted) communities.   It included aiding the first responders by
> giving them the ability to take a back pack full of equipment, set it
> up,  and operate quickly.   It stated that it wanted to produce a system
> of such satellites over a decade to be available 7/24.
>
> We have a concept, not a design, for a spacecraft.  This concept is an
> "upsizing" of the near cubical Eagle.  We are filling in the blanks on
> the concept in an attempt to present a design.
>
> The concepts we are building to include the ability to use the
> transponders on this spacecraft  365 days a year, in EVERY year the
> spacecraft is functional and to try and build  a spacecraft that will be
> there and still usable when the third in the constellation is launched.
> Do you think this is easy?  Of course not.  It is easy to pitch mud when
> you are not responsible for an outcome.
>
> We are attempting to have NO bad seasons.   We are attempting to have NO
> funny orbital problems.     We are attempting to have the gain antennas
> solidly usable over 70% of the entire orbit.  For these reasons and
> because of the desire to serve the CC&R customers,  this meant we had to
> use microwaves to get sufficient gain on the antennas on the spacecraft
> and the ground.  We fully understand that Dick Jansson,  Drew,  Dave,
> Tony, and others can give us anecdotes of how they can throw enough gain
> on their antenna system and make S band work for them.  I believe they
> will not be happy with a 60 cm dish but will require a much larger dish
> to be happy and I am certain they would do it.  I do not care.  They are
> not who I am computing for.  These are not the customers I am trying to
> serve.  The customers I want to serve for the future of AMSAT cannot be
> served by a scratchy SSB signal and a (now) 4 foot dish.  I have a
> mission directive from the board of directors you elected and voted for
> to serve these NEW customers.  Those who will be here when the third
> satellite is launched.   They will not be where Dave will be by then.  I
> apologize for the crassness of this remark, but I am trying to make a
> point.  I know Dave and have for nearly 30 years..  We are building for
> a guessed audience, with a guessed legal and RF environment,  with a
> guessed ability to deliver 3 such payloads over the next 13 years.
>
> COLD HARD CALCULATION went into this analysis based on our best guesses
> and analyses.   Given what we believe the environment will be  We can
> only do this on microwaves and we can only do it digitally.   PERIOD.
> End of story.  God (as demonstrated through the mathematics of Claude
> Shannon)  has dictated this outcome.  We did not sit in a back room and
> decide what new toys we would throw your way to delight ourselves and to
> screw you (no more smoke and no more drink in there,  we have grown old
> and boring) .  To do it,  I have to build a very complex antenna system
> that will take up most of the available area on the spacecraft for
> antennas.  I cannot build a three axis stabilized spacecraft (I do not
> have the team or the money to do it),  so I must do it with phased
> arrays.    Matt Ettus has given us a great head start on this design and
> Tom Clark and John Stephensen have done great work on the antennas so
> far.  We will test these antenna designs in the next twelve months
> thanks to a very generous antenna test range offer and design help by
> one of our members.
>
> The direction Jim and I gave our engineering team was that we cannot
> rely on this to work perfectly and meet every operational goal
> perfectly.  STUFF HAPPENS.   We are attempting to be ambitious but we
> absolutely must have a credible back up in case this system does not
> meet our expectations.   We now have the upgraded Mode B transponder
> design which I believe will be the sweetest one flown since Oscar 7's
> Mode B. Fully equipped with the channelized AGC (Leila or Stella),
> generating HELAPS with modern technology and new fantastic amplifier
> components.
>
> I gave the argument to our engineering team  that I have witnessed one
> experimental, new widget after another get built, flown, and then have
> its designers disheartened and dejected because it got "RUDAK'ed".  It
> never really gets used or fully developed.  It drifts into an inert lump
> that people mumble about when they are asked of their involvement.  I
> insisted on enough spacecraft power generation to run BOTH the linear
> transponder and the digital transponder simultaneously and 365 days a
> year,  EVERY year.  This is the single most expensive decision we have
> made.  We might spend 1/2 to 3/4 MILLION dollars on solar panels to
> accomplish this.  I have insisted we have enough antenna space to make
> all of the antennas credible and based on calculation of the required
> antenna gains to close the links.  Again,  Claude Shannon has
> interpreted the natural laws and dictated the outcome.   Cold hard
> calculation has gone into the needed solar generators,   and the size of
> spacecraft required to support this.
>
> It will be about 4 feet across and look initially like a scaled DOWN
> AO-40 at launch if the concept becomes our design.
>
> We cannot deliver the quality of services we are demanding of ourselves
> if we fly all of the bands to be flown on P3E.  We do not have the power
> or the antenna territory to meet our goals for these services.
>
> I have taken my direction from the board of directors of this
> organization.  They made the vision statement.  They can change it.  You
> elected them.
>
> Several things will happen in October.   We will install four
> directors.  I may, or may not,  be one of them.  The board will vote
> whether or not to retain me as the VP Engineering.  I have made almost
> NO ONE happy by slowing down those who drive me crazy with wanting to
> rush head long in a ready fire aim approach by demanding that we
> calculate our way to the vision statement to show the directors the
> consequences of the decision making processes.  I have to tell you,  I
> am damn proud of how much has been done in eleven months.   Stuff got
> put on hold that aggravated many.  We all make decisions about the way
> things have to go but I have done my best to aim us in a technically
> feasible direction.  I do not have time to do all the everyone wants me
> to do.  I will continue to do my best if I stay in the job.
>
> I offer the following.  If the board votes to change their vision
> statement and not to build the spacecraft we are proposing,  I will
> tender my resignation as VP Engineering since I will have failed to do
> the job they elected me to do which was to produce a usable concept to
> meet their vision.    I am not interested in flying a carbon copy of P3E
> when I know it makes no sense whatsoever.   I am 52 years old and one of
> the most active technical contributors in all of amateur radio.  I will
> not waste my time doing what I know in my heart and my head is not in
> the best interests of amateur radio even if it is currently perceived to
> be for the good of  the shrinking aging membership of AMSAT.  It would
> be irresponsible of me not to attempt to aid the organization in
> addressing a new group of members while attempting to thread the needle
> of serving our current members.  If elected to the board, and it changes
> direction,  I will offer my seat to the first alternate.  Vote for
> someone else if you do not want P3E built and you do not want the AMSAT
> vision statement attempted if you have not cast your vote.
>
> The story you have just been told should not have come out in this
> form.   It was NEVER meant to be displayed in this form.  The
> calculations were made at the first of July.  They have undergone
> several iterations and were not really put in there latest form until
> August.   In an attempt to get further interest from the microwave
> community, we made a decision to give a sneak peek to get some technical
> aid from RF specialists.  This has backfired badly because we,  the
> volunteers who have sacrificed countless hours on your behalf,  have not
> had the time to put together a hundred pages of supporting documentation
> to tell the story in a coherent fashion so not only do we look like
> idiots,  we have had to do things like waste 3.5 hours writing this
> silly note when I should have been asleep.
>
> Lastly.  I have been accused here of being a con artist.   I resent
> it.   I don't need to con anyone.  Frankly,  I don't have to be here at
> all.  I choose to be.
>
> Bob
> N4HY
>
> --
> AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
> NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
> "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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