[amsat-bb] RE: Transponder up time ?

["Stacey E. Mills" <w4sm@xxxxxxxxxx>]

>Stacy and /or ground control stations:
>Is there a power constraint or other factors that require the bird to be up
>for such restricted periods?
>In my portable location here in FL and with the bird only providing limited
>favorable squints, it is a real kick in the head to be an hour through a 3
>hour favorable window only to have the transponder taken down.  If there is
>not a great reason to the contrary, couldn't the up schedule be predicated
>on reasonable squints, not MAs. I know that all portions of the earth plate
>do not see the same squints, but I think that we could open up much more of
>the pass if that was a consideration.
>Thank you in advance for your thoughts.
>Gunther Meisse
>W8GSM

Hi Gunther,
I'm not quite sure what you mean.  You ask why the passband can't be 
predicted on reasonable squints rather than MA's, but the two are directly 
related, based on the ALON/ALAT.  The satellite software triggers on MA 
units.  The trigger points are set by the command team after reviewing the 
corresponding squints, etc. The passbands are currently active from MA = 5 
to 100, except for a 4 MA period from MA 30 to 34 (approx. 18 minutes), 
when the K-band Tx. is on for further characterization of its radiation 
pattern.  That's essentially 91 active MA units or 6.8 hours per orbit.  By 
MA = 100 the squint is currently 40 degs or greater.  With the current 
ALON/ALAT and given the range involved, the transponder is of no value 
beyond that.  In fact my own monitoring shows no activity substantially 
before MA =100.  Are you talking about the brief period from MA = 30 to 34 
when the transponder is off?  If so, just hang on for 18 minutes and it 
will be back on.

Of course, as the ALON approaches 360, we will lengthen the passband segment.



-- 
  ________________________________________________________________________
  Stacey E. Mills, W4SM    WWW:    http://www.cstone.net/~w4sm/ham1.html
    Charlottesville, VA     PGP key: http://www.cstone.net/~w4sm/key
  ________________________________________________________________________

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