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Re: What Secrets? - My mind is going...


normally I would not post this here, because all this is stupid
and there are more interesting things to discuss and spent time on..
I apologize for this..

Franklin Antonio wrote:

> My experience asking questions of Peter and AMSAT-DL is that they are not answered.  I had a very frustrating experience trying to get some very simple information about AO40 before launch.  His caveat therefore is disingenuous. 

and than...

> At 12:28 PM 12/8/2003, ChrisGW6KZZ@aol.com wrote:
>> Franklin I think your comments are unjust to Peter and I hope you have 
>> the decency to apologise.
> My comments were based on fact.

So here are my facts!!!!!!!

I just scanned my OUTBOX and to my surprise what did I find, a lot of answers..

"Dave, my mind is going...   Dave...."

73s Peter, DB2OS

-------- Original Message --------
Subject: Re: [amsat-bb] P3D wobble [2nd try]
Date: Sun, 25 Jun 2000 10:56:14 +0100
From: Peter Guelzow <Peter.Guelzow@arcormail.de>
To: Franklin Antonio <antonio@qualcomm.com>
References: <>

Hi Franklin,

Franklin Antonio wrote:

 > No answer first time I posted this, so I'll try again:

I was the last week in Paris for a meeting with Arianespace
and the other P3D experts mostly have not subscribed to amsat-bb
(I have not yet given up).

 > I heard an explantion (well I think perhaps it was half of an explanation)
 > about the earth-sensor on P3D.  I've heard that the earth sensor is fixed,
 > like the earth-sensor on a spinning bird, and thus requires the satellite
 > to rock back and forth during normal operation in order to see the edges of
 > the earth, and thus sense the position of the earth.  (Actually, "rock"
 > gives the impression that this is a one-dimensional motion, but obviously
 > this involves rotation in two angular dimensions.)
 > Such rocking would obviously be controlled by software, and carried out via
 > the reaction wheels.  If this is correct, what will the period of this
 > rocking be?

You explanation is quite correct.  The s/c needs to me moved back and
forth in order to get a sense from the fixed earth sensor. Indeed we
also have sun sensors (fixed) and a 3-axis sunsensor. With the 2-dimensional
sun sensor information, you only need a one-dimensional motion
for the rocking of the earth sensor..
I don't know what the rocking period will be, but I guess it will be
very slowly.  Maybe I will ask Karl DJ4ZC when I talk to him next time,
he is designing the software for the navigation.
We also have our camera on the IHU2 and we have ideas to use image processing
to use it as an earth sensor too. If it works, no rocking would be required..

I hope this helps..

73s Peter


-------- Original Message --------
Subject: Re: [amsat-bb] P3D uplink power requirements
Date: Mon, 26 Jun 2000 12:56:34 +0100
From: Peter Guelzow <Peter.Guelzow@arcormail.de>
To: Franklin Antonio <antonio@qualcomm.com>
References: <>

Hi Franklin,

I have some data from Mirek Kasal OK2AQK to precise the link budget:

1) L band uplink, high gain antenna, satellite at apogee:

Gain of the our on-board SBF is 15 dBiC (ref. by Stan). My estimation of
antenna noise temp. is 70 K (at apogee, antenna pointed to the Earth).
Feed losses are 0,5 dB (two SMA connectors and 25 cm of cable), temp. of
the cable will be about 290 K. Equivalent noise temperature of the
receiver is 175 K. Then a system equivalent noise temp is

Tn = 70/1.122 + 290(1 - 1/1.122) + 175 =  62.4 + 31.5 + 175 = 269 K
G = 15 - 0.5 = 14.5 dB.
G/T = 14.5 - 10 log 269 = - 9.8 dB/K

2) S band uplink (the same condition):

Gain of the on-board dish is 21 dBiC (ref. by Stan). My estimation of
antenna noise temp. is 130 K (at apogee, antenna pointed to the Earth).
Feed losses are 1 dB (circulator, connectors, cable), temp. of the cable
will be about 290 K. Equivalent noise temperature of the receiver with the
in built preamp may be 150 K. Then the system equivalent noise temp is

Tn = 130/1.259 + 290(1 - 1/1.259) + 150 = 103.3 + 60 + 150 = 313 K
G = 21 - 1 = 20 dB.
G/T = 20 - 10 log 313 = - 5.0 dB/K

I hope this helps,
  73s Peter


-------- Original Message --------
Subject: Re: [amsat-bb] more P3D questions: orbit / xponder gain
Date: Sat, 01 Jul 2000 19:46:44 +0100
From: Peter Guelzow <Peter.Guelzow@arcormail.de>
To: Franklin Antonio <antonio@qualcomm.com>
References: <>

Hi Franklin,

Franklin Antonio wrote:
 > I have a couple more questions about numbers for P3D:
 > I'd like to know the estimated apogee.  I've heard that the apogee that has
 > been published is no longer best estimate, due to spacecraft weight.  If
 > so, I'd like to know the present best estimate.

There will be an article in the upcomming AMSAT-NA Journal,
but here some preliminary Keps:

Launch: 8-1-2000  23:00:00 UT
Apogee: 39122 km, Perigee 590 km

P3D 001
1 99001U 00099Z   00214.97200000  .00000000  00000-0  00000-0 0   016
2 99001   6.5000 109.0000 7340000 176.0000   0.0000  2.04300000    09

Launch: 8-1-2000  23:00:00 UT
Apogee: 34122 km, Perigee 590 km

P3D 002
1 99002U 00099Z   00214.97200000  .00000000  00000-0  00000-0 0   017
2 99002   6.5000 109.0000 7060000 176.0000   0.0000  2.37400000    06

Data Sets for the planned 16 Hour Orbit of P3-D.

Date:  7 January 2002 (Orbit #600)

P3D 003
1 99003U 00099Z   02007.00000000  .00000000  00000-0  00000-0 0   034
2 99003  63.5000 327.0000 7830000 352.0000   0.0000  1.50000000  6009

Date: 1 Juli 2013 (Orbit #6900):

P3D 004
1 99004U 00099Z   13182.00000000  .00000000  00000-0  00000-0 0   042
2 99004  74.0000  87.0000 6000000 315.0000   0.0000  1.50000000 69006

To optimize the usage of the available fuel, we might go to an
intermediate apogee of 60,000 to 75,000 km !
More in the article...

73s Peter DB2OS


-------- Original Message --------
Subject: Re: AO40 mission reprioritization
Date: Wed, 03 Jan 2001 23:27:06 +0100
From: Peter Guelzow <Peter.Guelzow@arcormail.de>
To: Franklin Antonio <antonio@qualcomm.com>
CC: P3-D development group <p3d-dev@amsat.org>, karn@qualcomm.com, 
References: <>

Dear Franklin,

thanks for your comments, you made indeed some valid points.
However, I think it is too early re-define or discuss the
mission of the S/C now.

This can only be done as soon as the recovery efforts are completed and
the spacecraft is working "normal".  We are not yet there...

Priority now is to evaluate the communication links, probably get
V and even U band working again.  This is under heavy progress, but
takes time..

Next on the list is to try magnetorquing and improve sun angle and

Than it will also take some time to evaluate the status of the
various other systems and experiments. This will certainly include
the Arcjet and the wheels as earliest as possible.

Once this is completed and we have a complete overview, than
we can think about re-defining the mission of AO-40, whatever
it will be...

Best regards
   Peter DB2OS

Franklin Antonio wrote:
 > I have a thought about the situation we find ourselves in.  Know you guys
 > are busy, but I just want to interject this thought.
 > We've got a satellite that we are pretty sure has some serious damage.  We
 > don't yet know the extent of the damage.  Some scenarios which might
 > explain what has happened involve propellant release, possibly inside the
 > spacecraft.  If indeed hydrazine has been released inside the spacecraft,
 > then we could experience additional electrical failures of just about any
 > kind at just about any time.  Wiring harnesses likely have little defense
 > against hydrazine.
 > Our knowledge is uncertain, and that it will take some time to even know
 > where we are.  However, some time soon we should consider how we define the
 > "mission" given the present situation.  A potentially shortened lifetime
 > might lead us to redefine the mission.
 > There are some things that we would really like to test, if it is possible
 > to do so, in the possibly shortened time available.  Would be a shame to
 > have flown the arc-jet engine, for example, then not get a chance to test
 > it.  It is likely that we would want to use an arc-jet engine on a future
 > spacecraft, so some experience running it on this mission could be of very
 > great value.
 > We all hope that AO40 will have a long life of some kind, and that
 > certainly is still a possibility.  (AO10 has certainly demonstrated that a
 > partially functioning spacecraft can still be quite useful for a very long
 > time.)  However, considering the possibility that AO40's life may be much
 > shorter than plan, we should consider redefining the mission to prioritize
 > engineering evaluation of technology where such evaluation has value for
 > future missions.  I would put the arc-jet engine first on such a list,
 > followed by the momentum wheels.


and probably more...

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