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Re: An Open Letter To AMSAT






>From: Jon Ogden <na9d@mindspring.com>
> > For this to work (and I am speculating here although
> > it could be cleared up pretty quick) this would require as a minimal 
>thing
> > that at least one command reciever be working and two the "master reset"
> > circuitry be intact and three that their be something functional to 
>reset.
>
>The master reset circuitry is able to be activated independent of the IHU.
>Additionally, the L band RX is on ALL the time.  And either the 2m or 70cm
>RX is on.  So there is always at least 2 receivers functional at all times.

As I said it requires three things.  It requires a command reciever to be on 
at all times, the master reset circuitry intact and THAT THERE BE SOMETHING 
FUNCTIONAL TO RESET.  All this of course requires power but MY GUESS would 
be (and its that) that of the three the big deal is "something to 
reset"....ie the computer works.


>
>There is always a possibility that the RF circuitry failed, but having been
>an RF designer, I know a little about that.  Most of the time you have
>either an "infant mortality" or failure after a long, long period of time.
>Very rarely does something work for a couple of weeks and then stop.  It is
>not impossible, but IMHO, unlikely.<<

It would strike me as unlikely that a crib death is what took the whole bird 
down unless it was a crib death of lets say the number 1 computer.

>
> >
> > So to summarize based just on what the folks have let us know it strikes 
>me
> > that 1) there is a window that closes at whatever time plus interval 
>that
> > the on board reset will fire then 2) there is a last ditch chance to 
>send
> > this master reset.  I would wonder what has to be working on the 
>satellite
> > for that to work...?
>
>There is no window that closes as you speak of.  The COMMAND-ASSIST mode
>goes into affect after a certain amount of time of no commands being
>received.  From what I have read, we have never reached the point of the
>COMMAND-ASSIST routine activating.  When it happens, the bird will try to
>transmit telemetry or a carrier or whatever on various combinations of 
>bands
>and antennas.  If this functionality works, we will all know it.  Again,
>this bird is loud.  If it begins transmitting, we won't need EME arrays to
>hear it.
>
>73,
>
>Jon
>NA9D

I dont think you read what I wrote (or I wasnt clear).

<<There is no window that closes as you speak of.  The COMMAND-ASSIST mode
>goes into affect after a certain amount of time of no commands being
>received.  From what I have read, we have never reached the point of the
>COMMAND-ASSIST routine activating.  <<

I think a window does close.  The Command assist mode goes into effect AFTER 
A CERTIAN time of no commands being recieved.  There IS A WINDOW that exist 
from the time the last command was heard (which one doesnt know when that 
was) plus the "certian amount of time".  MY GUESS is that at some point they 
have stopped sending commands SO A WINDOW DOES EXIST...between the last one 
that was heard (whenever that was) and the last one that was sent for 
possible timer activation.

So for instance.  Lets say the CA mode goes into effect four days after the 
last command was "heard".  That last command was heard on Thursday...well 
TH, FR, SAT, SUN...ok that one should have fired.  But lets say the last 
command was actually sent on well SUN.  SO MN, TUES, WED, TH sort of close 
it out.  IE if the last command was sent that date plus the interval closes 
out when a possible command activation COULD occur.  So when one would give 
up hope on thecommand activation would be the date the last command was 
"sent" plus the interval.

I dont know when that occurs....ie I dont know when the last command was 
sent.
>


Robert Oler WB5MZO

BTW as a totally off topic note my president has always been the one who has 
taken the oath of office and is serving the designated term.

Robert
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