Date: Mon, 3 Jan 94 04:30:36 PST
From: Ham-Space Mailing List and Newsgroup <ham-space@ucsd.edu>
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Subject: Ham-Space Digest V93 #130
To: Ham-Space
Ham-Space Digest Mon, 3 Jan 94 Volume 93 : Issue 130
Today's Topics:
ANS Bulletin 001.01
ANS Bulletin 001.02
TrakBox panel layout
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Date: Sun, 2 Jan 1994 14:02:34 -0700
From: library.ucla.edu!news.mic.ucla.edu!unixg.ubc.ca!nntp.cs.ubc.ca!alberta!nebulus!ve6mgs!usenet@network.ucsd.edu
Subject: ANS Bulletin 001.01
To: ham-space@ucsd.edu
SB AMSAT @ WW $ANS-001.01
HR AMSAT NEWS SERVICE BULLETIN 001.01 FROM AMSAT HQ
SILVER SPRING, MD January 1, 1994
TO ALL RADIO AMATEURS BT
BID: $ANS-001.01
A number of messages have recently been posted to the AMSAT BBS
concerning the schedules for the various satellites and how they
are arrived at. In the case of OSCAR-13, the schedule is
determined by the AO-13 Command Team consisting of James Miller
G3RUH, Peter Guelzow DB2OS and Graham Ratcliff VK5AGR. As to how
these volunteers determine the schedule, a very fine set of
comments was posted by Paul Beckmann WA0RSE Internet address
wa0rse@amsat.org. The AMSAT News Service thanks Paul for his well-
put comments and has taken the liberty of extracting them for this
bulletin.
Paul begins by asking himself: What determines the mode schedule
for a satellite? He says thae he found an answer in the very
clearly written piece in the 1993 Space Symposium Proceedings by,
you guessed it, James, G3RUH.
In his attempt to put the article by James in terms that may not be
obvious to new to satellites as well as many not so new
"bird-watchers", Paul offers a list of some of the important
considerations:
1. All modern satellites are battery-powered with solar cell
recharging systems. In order to work, the batteries must stay
charged.
2. Most satellites do not have solar cells covering their entire
surface. This means the attitude of the satellite with relation to
the sun must be managed to keep the batteries charged.
3. The antennas are fixed to the satellite, not steerable, and
necessarily "go along for the ride" when accomplishing Item 2.)
4. Each mode involves a receiver, a transmitter, and a pair of
antennas. The receivers vary in sensitivity, the transmitters in
power, and the antennas in gain and beamwidth.
5. Because of Item 3, the characteristics of item 4 allow
transponder operation only in particular modes, when the distances
and spacecraft attitudes are within certain limits. For example,
a narrowbeam antenna pointing away from the Earth will not support
communications. If a particular mode requires the use of that
antenna, it would not do any good to place the satellite in that
mode, no matter how badly it was desired. To change the attitude
of the spacecraft to point the antenna at the Earth could very well
compromise solar cell illumination, hence battery charge, hence
spacecraft operation - and possibly even its life expectancy.
6. Because some modes draw more power than others, the battery
power must be budgeted. This also constrains how long the satellite
can operate in any particular mode.
Paul admits to possibly missing some other major points, but he
believes that these demonstrate to him, at least, that the mode
schedule on AO-13, or any other bird, is not a self-serving
decision made by some "elite superclass" who treat the bird as a
"toy", but are considered decisions, constrained by the physics of
the orbit, solar cells, batteries, equipment aboard, antennas,
etc., designed to offer the best long-term schedule of transponder
operation and to further the state-of-the-art for the next birds'
designs.
WA0RSE strongly suggests reading the article by James in the
Proceedings. He says that he was amazed at the number of
specialized programs that had been written, complete with graphical
output, to aid in the decision-making process to keep the AO-13
satellite operational. He expressed his opinion that
James, and others like him, should be thanked for bringing clear
explanations like these to the rest of us and for fostering
experimentation in modes that have proven to provide better two-way
satellite communications for our fellow hams across the globe.
Paul sums up his message by saying that we need everyone interested
in AMSAT, with their opinions, tempers, passions, talents, and good
humor. He also wishes all a Happy New Year. Peace on Earth. Good
will toward all.
Information on ordering a copy of the Space Symposium Proceedings,
which contains James Miller's article can be found on page 12 of
the Nov/Dec AMSAT Journal.
/EX
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Date: Sat, 1 Jan 1994 16:38:22 -0700
From: yeshua.marcam.com!zip.eecs.umich.edu!destroyer!nntp.cs.ubc.ca!alberta!nebulus!ve6mgs!usenet@uunet.uu.net
Subject: ANS Bulletin 001.02
To: ham-space@ucsd.edu
SB ALL @ AMSAT $ANS-001.02
HR AMSAT NEWS SERVICE BULLETIN 001.02 FROM AMSAT HQ
SILVER SPRING, MD January 1, 1994
TO ALL RADIO AMATEURS BT
BID: $ANS-001.02
RV3DR, QSL manager for MIR contacts, advises that on December 24,
1993, December 31, 1993 and January 6, 1994 the MIR space station
will be transmitting special digitized voice messages on its
normal frequency of 145.55 MHz. The message repeats every tow
minutes. Sergey says that the developer of this equipment is
DL2MDE.
ANS thanks RV3DR for the information that went into this bulletin
and James Mollica N2NRD for relaying it to us.
/EX
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Date: Mon, 3 Jan 1994 04:51:53 GMT
From: netcomsv!netcom.com!fmitch@decwrl.dec.com
Subject: TrakBox panel layout
To: ham-space@ucsd.edu
this is a generic reply to all email in response to my trakbox panel
layout post to the usenet and i am also posting this msg on compuserve...
the panel layout is enclosure specific for the Bud LB-1663 Contempo
box... this box is a 'ten-tec' type box, gray in color with black plastic
side panels, with the following dimensions:
3 1/4" high
7 1/32" wide
7 3/16" deep
the box is a mite too small for the pcb to fit into the pcb grooves molded in
the plastic side panels, therefore you have to *trim* the printed circuit
board by about 3/16 ths of an inch... this is easily done with a hand file...
it is *much* easier to do if you haven't populated the board... if you
don't want to trim your pcb you can still use the layout as an
example of "how to do it"...
the current layout is for the switches furnished with the first batch of kits...
the second batch of kits is currently being 'kitted'... the satellite
selector switch for the second batch of kits will be a thumbwheel type...
i am being loaned one of the new type switches and will modify the panel
layout to accomodate either switch...
i will be posting the corel draw file and also a gif file to compuserve as soon
as we have the layout modified for the new type selector switch... (if anyone
needs a different file type please let me know... i can furnish any file type
supported as an export file from corel draw 3) ... look for
a filed named tboxpanl.zip or something similar... a warning on the
gif file --- it looses much detail, and is only useful for you to grab a
quick peek at the layout...
i am looking for a ftp site to upload the files for internet access, any
suggestions for a public accessable location will be appreciated...
if you need the files directly, you can download the zip file from
my data line, see below, or send me a blank, *formatted* disk of any
flavor, along with return postage... i will dump the files on your disk and
mail them back to you...
thanks,
mitch, wa4osr
usnail: felton mitchell, 11 midtown park, e., mobile, al 36606 usa
packet: WA4OSR@W4IAX.#MOBAL.AL.USA.NA
internet: fmitch@netcom.com
landline: 205-342-7259 home, 205-476-4100 work, 205-476-0465 fax
205-342-4073 data
--
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fmitch@netcom.com
Felton "Mitch" Mitchell, WA4OSR in Mobile, Alabama USA
205-342-7259 home, 205-476-4100 work, 205-476-0465 FAX
co-sysop for W4IAX bbs running fbb ... sysop for WA4OSR DXCluster in Mobile..
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End of Ham-Space Digest V93 #130
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