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Re: pt3 telemetry



Jon,
Good morning. (0) What Phil calculated was doppler shift resulting from the
relative velocity caused by the rotation of the spacecraft.  Not frequency drift.
We should not confuse this with the long term doppler shift caused by the relative
orbital velocities.  (1) We don't know for sure what the rotation rate is.
However DB2OS stated back on Dec 27th, "The real spin rate appears to be in the
range of 16 RPM (as measured by the doppler wobbling on the S-Band beacon)."  All
measurements since then seem to confirm the higher rotation rate.  (2) The Helium
pressure dropped after the first burn attempt and again after the second burn
attempt.  As shown by telemetry.  (3) S-Band is great! (4) Phil's calculation is
not a measurement. (5) Your right MMH is not very nice stuff.
73's de Rich @ WC8J

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Jon Ogden wrote:

> on 1/4/01 7:58 PM, Richard D. Burgan at wc8j@raex.com wrote:
>  I saw an AMSAT-BB post yesterday where Phil, KA9Q calculated the
> > doppler at +/- 14 Hz.  All the indications I had were that it is more than
> > that.  So there is something going on.  I roughly measured the rotation rate
> > at
> > 17.4 rpm.
>
> I think Phil was talking about frequency drift from the rotation of the
> spacecraft not the Doppler from the normal fact that the satellite is moving
> relative to us in its orbit.
>
> >
> > I am curious about the following questions (among others):
> >
> > 1. How did the spin rate get from 9 rpm to 17 rpm?  Where did the energy
> > come from?
>
> That is unknown as of yet.  The control team acknowledges that the spin rate
> shown in the telemetry does not match that calculated by receiving the
> signal and measuring it like you did.  They have not said what happened.
>
> >
> > 2. What happened to lower the Helium pressure between burn attempts?
>
> Not sure what you mean.  The He pressure after recovering the bird has shown
> to be right where it should be.  In between burns there really was no helium
> release since the valves didn't open correctly for the first burn.  The only
> helium release was for the second burn.  At least this is how I understand
> it.
>
> >
> > 3. Do other stations here the same audio pattern?
>
> Don't have mode S capability yet.  :-(
> >
> > 4. How could we accurately measure the "doppler" wobble from AO-40?
>
> I think Phil pretty accurately calculated it.
>
> >
> > 5. What do the propellants do to wiring and other spacecraft structure if
> > they leak?
>
> Probably something that is not very good.  From what I've read it seems like
> the MMH is pretty reactive.  To me that would mean that any of the
> propellants that might leak could be pretty corrosive and destructive to
> circuits, etc.  But we've not been given any indication that this is what
> happened.
>
> >
> > Lets hope we get some more information soon!  That would be GOOD news.
>
> Well, let's hope we get GOOD news in that information!  :-)
>
> 73,
>
> Jon
> NA9D
>
> -------------------------------------
> Jon Ogden
> NA9D (ex: KE9NA)
>
> Member:  ARRL, AMSAT, DXCC, NRA
>
> http://www.qsl.net/ke9na
>
> "A life lived in fear is a life half lived."

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