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CX2SA > SATDIG 22.04.08 15:05l 393 Lines 15969 Bytes #999 (0) @ WW
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From: CX2SA@CX2SA.LAV.URY.SA
To : SATDIG@WW
Message: 8
Date: Tue, 22 Apr 2008 08:27:23 -0400
From: "Roger Kolakowski" <rogerkola(AT)aol.com>
Subject: [amsat-bb] Re: Ridge Test Results
To: "Nathaniel S. Parsons" <nsp25(AT)cornell.edu>, "Amateur Radio Club"
<hamradio-l(AT)list.cornell.edu>, <amsat-bb(AT)amsat.org>,
<gs(AT)cusat.cornell.edu>, <tc(AT)cusat.cornell.edu>, "Dan Oltrogge"
<Oltrogge(AT)1earthresearch.com>
Message-ID: <013101c8a474$3851b6a0$0200a8c0(AT)Tanguray>
Content-Type: text/plain; charset="iso-8859-1"
Hi Nate...
Now that you have made some progress and secured some successful
communication, it might be time to optimize your base (control) station.
You mentioned in your first post that you were using "RG-8" coax but not how
long a run of it you had. At 435 mHz, RG-8/U is no where near optimal and
connectors do matter. Type "N" connectors would be best and a less lossy
coax might help you find those "missing" dB.
How long is your coax run and is it continuous or does it have splices?
Roger
WA1KAT
----- Original Message -----
From: "Nathaniel S. Parsons" <nsp25(AT)cornell.edu>
To: "Amateur Radio Club" <hamradio-l(AT)list.cornell.edu>;
<amsat-bb(AT)amsat.org>; <gs(AT)cusat.cornell.edu>; <tc(AT)cusat.cornell.edu>;
"Dan
Oltrogge" <Oltrogge(AT)1earthresearch.com>
Sent: Monday, April 21, 2008 11:43 PM
Subject: [amsat-bb] Re: Ridge Test Results
> I'm sorry we didn't get in touch, but my cell phone died while we were out
> there.
>
> Were were listening on 146.610, but didn't hear anything except the time.
> Maybe we weren't using it correctly?
>
> If you could get all of that material tomorrow, that would be excellent.
We
> do have access to sanding paper, a file, and a grinding wheel, though.
>
> On Mon, Apr 21, 2008 at 11:26 PM, F. Kevin Feeney <fkf1(AT)cornell.edu>
wrote:
>
> > Were you transmitting in just one direction or from TS to D7 and then
from
> > D7 to TS?
> >
>
> Via packet, only TS to D7 (some were sent the other way, but we were told
> having attenuators on the RX side would give us unreliable data). By
voice,
> both directions, and while that signal was fuzzy at higher attenuation, it
> never completely cut out. For the packets, we always received them on the
> radio, but the number recorded was the amount passed on to the computer.
>
> > Why list the power settings in each radio if you are only transmitting
> > from the TS2000 to the D7? That confused me.
>
>
> Just for completeness.
>
> >
> > How successful have you been at running the radios in 9600 baud mode in
> > previous testing? If you don't have many weeks of positive results in
that
> > mode at this point with whatever antennas, I'd be very wary of
committing to
> > a launch.
>
>
> Not very. We could complete the mission at 1200 baud, though, it would
just
> take longer to move data back and forth.
>
> > so what are the power listings for each radio telling us? To me I think
> > I'm seeing that your circularly polarized antenna isn't quite as good in
> > horizontal mode as in vertical? You have to have less attenuation in
place
> > to get two good packets per two tries for the same power settings in
> > horizontal as for vertical. looks like about a 15 db difference? (30 vs
45?)
> > That says your circular antenna "circularity" is suspect. Is it a helix?
> > Crossed yagis with phasing harness? Is it up in the air off the support
> > structure? Are the feedlines trailed out the back of the antenna, or do
they
> > come down through the elements to the mast?
>
>
> I'm sorry that I wasn't clear, but all our rotations were in the direction
> of the other station. So, if an observer were looking at us from the side,
>
> Vertical:
> "satellite" |
> XXXXX- Ground
>
> Horizontal:
> "satellite" --
> XXXXX-Ground
>
> 45 deg:
> "satellite" /
> XXXXX-Ground
>
> So we didn't really test the circularity of the ground antenna, but the
gain
> pattern of the rubber duck.
>
>
> > Wait - were you testing the loop during any of this? I thought all of
the
> > measurements were made with the rubber duck only in three orientations,
> > vertical, horizonatal and 45 degree. Where is the loop data shown?
>
>
> The loop data is the 10 dB figure mentioned in my first email. Under these
> same conditions on Friday, the loop only worked up to 10dB.
>
> Also, I can use a network analyzer tomorrow at 2PM. Is it worth analyzing
> the square loop antenna at this point?
>
> -Nate
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 9
Date: Tue, 22 Apr 2008 13:54:17 +0100
From: Clive Wallis <clivew(AT)zetnet.co.uk>
Subject: [amsat-bb] FINAL MONTHLY OSCAR-11 REPORT
To: amsat-bb(AT)amsat.org
Message-ID: <3130303031373237480DEE0975(AT)zetnet.co.uk>
FINAL MONTHLY OSCAR-11 REPORT
21 April 2008
RECEPTION REPORTS REQUESTED!
In the years ahead, it is possible that you may hear OSCAR-11, by accident,
when tuning round the frequency. If you are able to record the satellite on
audio tape or as a WAV file (not MP3), please do so, as it is unlikely
that it will be heard on the next pass!
Please send reception reports to xxxxx(AT)amsat.org (replace xxxxx by
g3cwv) or post to amsat-bb. If you have a file, please let me know what
you have, before sending it!
If you need to hear what the satellite sounds like, please visit my website
www.users.zetnet.co.uk/clivew/ The satellite transmits on 145.826 MHz. set
receiver to NBFM.
----------------------------
This is the 144th monthly report for OSCAR-11. Unless there is an
unexpected change of status (such as occured with OSCAR-7), I'm expecting
this to be my last report.
This report covers the period from 17 March to 21 April 2008. During
this period the satellite has not been heard and no reports of reception
have been received.
Transmissions were expected to resume on 24 March, after the beacon
switched-off on 14 March. However, permanent eclipses started a few days
beforehand, which probably caused the transmission period to be terminated
prematurely. It is now unlikely that the satellite will support any
sustained period of operation, and will only transmit for a short time,
possibly less than a single orbit, every 21 days.
I am indebted to all those who sent reception reports during the last 12
years. Initially there was much interest in hearing the mode-S beacon,
which was very weak. Recently, interest has changed to hearing when the
two metre beacon switched on/off. Special thanks must go to Jeff KB2M who
recorded telemetry during my holidays, and Peter ZL3TC, who has monitored
the beacon daily, during recent months. Many thanks to everyone.
The Beacon frequencies are -
VHF 145.826 MHz. AFSK FM ASCII Telemetry
UHF 435.025 MHz. OFF
S-band 2401.5 MHz. OFF
The satellite is now subject to eclipses during every orbit. Long term
predictions indicate that eclipses will occur until 2019, when there will
be some eclipse free periods until 2023. However these very long term
predictions should be regarded with caution, as large tracking errors can
accumulate over long periods of time.
When telemetry was last received it showed that one of the solar arrays had
failed, and there was a large unexplained current drain on the main 14 volt
bus. After 24 years in orbit the battery has undergone over 100,000 partial
charge/discharge cycles, and observations suggest that it cannot power the
satellite during eclipses lasting more than about ten minutes, or
sometimes even during periods of poor solar attitude.
The current status of the satellite, is that all the analogue telemetry
channels, 0 to 59 are zero, ie they have failed. The status channels 60 to
67 are still working. The real time clock is showing a large accumulated
error, although over short periods timekeeping is accurate to a few
seconds per month. When last heard the clock was 83.0958 days slow. The
day of the month has a bit stuck at 'one' so the day of the month may show
an error of +40 days for some dates. The time display has switched into 12
hour mode. Unfortunately, there is no AM/PM indicator, since the time
display format was designed for 24 hour mode.
The spacecraft computer and active attitude control system have switched
OFF, ie. the satellite' attitude is controlled only by the passive gravity
boom gradient, and the satellite is free to spin at any speed.
The watchdog timer now operates on a 20 day cycle. The ON/OFF times have
tended to be very consistent. The average of many observations show this to
be 20.7 days, ie. 10.3 days ON followed by 10.4 days OFF. However, poor
solar attitude may result may result in a low 14 volt line supply, which
may cause the beacon to switch OFF prematurely, and reset the watchdog
timer cycle. When this occurs, the beacon is OFF for 20.7 days.
OSCAR-11 was the second satellite from the University of Surrey,
www.ee.surrey.ac.uk/SSC. It was designed, built and launched, within a
time scale of six months, by a team headed by Martin Sweeting G3YJO.
Amateur radio groups working at various locations in the world, also
contributed to the project. It used commercially available 'off the shelf'
components (COTS). Following the success of these satellites, in 1985
Surrey Satellite Technology Ltd. www.sstl.co.uk was formed, as a commercial
venture. This grew into a major company which has produced over 27 small
satellite projects for a global market.
The University of Surrey has recently agreed to sell it's major
shareholding to EADS-Astrium. This agreement is now awaiting regulatory
approval. The joint company will have the experience of manufacturing
large and small satellites, for geo-synchronous and low earth orbits.
In regognition of his work, Martin G3YJO, was appointed Professor at the
University of Surrey. He received an OBE in the 1995 Queens birthday
honours list, and in 2002 a knighthood in the New Year's honours list.
Listeners to OSCAR-11 may be interested in visiting my website, which is
being updated to reflect the current status of the satellite. If you need
to know what OSCAR-11 should sound like, there is a short audio clip for
you to hear. The last telemetry received from the satellite is available
for download. The website contains an archive of news & telemetry data
which has now been updated. It also contains details about using a
soundcard or hardware demodulators for data capture. There is software for
capturing data, and decoding ASCII telemetry. The URL is
www.users.zetnet.co.uk/clivew/
If you place this bulletin on a terrestrial packet network, please
use the bulletin identifier $BID:U2RPT144.CWV, to prevent duplication.
73 Clive G3CWV xxxxx(AT)amsat.org (please replace xxxxx by g3cwv)
------------------------------
Message: 10
Date: Tue, 22 Apr 2008 13:22:34 +0000
From: kb2m(AT)comcast.net
Subject: [amsat-bb] Re: FINAL MONTHLY OSCAR-11 REPORT
To: Clive Wallis <clivew(AT)zetnet.co.uk>, amsat-bb(AT)amsat.org
Message-ID:
<042220081322.6670.480DE699000CB58E00001A0E220076018003CD0D05(AT)comcast
.net>
Content-Type: text/plain
It was a pleasure to work with you on UO-11 Clive. I still listen for her at
least a couple of times a week, last time was yesterday. And, I will continue
to do so in the future.
73 Jeff kb2m
-------------- Original message --------------
From: Clive Wallis <clivew(AT)zetnet.co.uk>
>
> FINAL MONTHLY OSCAR-11 REPORT
>
> 21 April 2008
>
> RECEPTION REPORTS REQUESTED!
>
> In the years ahead, it is possible that you may hear OSCAR-11, by accident,
> when tuning round the frequency. If you are able to record the satellite on
> audio tape or as a WAV file (not MP3), please do so, as it is unlikely
> that it will be heard on the next pass!
>
> Please send reception reports to xxxxx(AT)amsat.org (replace xxxxx by
> g3cwv) or post to amsat-bb. If you have a file, please let me know what
> you have, before sending it!
>
> If you need to hear what the satellite sounds like, please visit my website
> www.users.zetnet.co.uk/clivew/ The satellite transmits on 145.826 MHz. set
> receiver to NBFM.
>
> ----------------------------
>
> This is the 144th monthly report for OSCAR-11. Unless there is an
> unexpected change of status (such as occured with OSCAR-7), I'm expecting
> this to be my last report.
>
> This report covers the period from 17 March to 21 April 2008. During
> this period the satellite has not been heard and no reports of reception
> have been received.
>
> Transmissions were expected to resume on 24 March, after the beacon
> switched-off on 14 March. However, permanent eclipses started a few days
> beforehand, which probably caused the transmission period to be terminated
> prematurely. It is now unlikely that the satellite will support any
> sustained period of operation, and will only transmit for a short time,
> possibly less than a single orbit, every 21 days.
>
> I am indebted to all those who sent reception reports during the last 12
> years. Initially there was much interest in hearing the mode-S beacon,
> which was very weak. Recently, interest has changed to hearing when the
> two metre beacon switched on/off. Special thanks must go to Jeff KB2M who
> recorded telemetry during my holidays, and Peter ZL3TC, who has monitored
> the beacon daily, during recent months. Many thanks to everyone.
------------------------------
Message: 11
Date: Tue, 22 Apr 2008 09:18:23 -0400
From: "Laurence 'Mike' Hammer" <ldh3(AT)cornell.edu>
Subject: [amsat-bb] Re: Ridge Test Results
To: "Amateur Radio Club " <hamradio-l(AT)list.cornell.edu>
Cc: tc(AT)cusat.cornell.edu, Dan Oltrogge <Oltrogge(AT)1earthresearch.com>,
amsat-bb(AT)amsat.org, gs(AT)cusat.cornell.edu
Message-ID:
<6.2.1.2.2.20080422090808.04508ad0(AT)postoffice9.mail.cornell.edu>
Content-Type: text/plain; charset="us-ascii"; format=flowed
Hi Nathaniel,
Been watching this thread. The only bits of info I haven't seen go across
yet --
Antennas act very differently when the radiator part of the antenna is in
close proximity to the RF ground. If you have modelled the antenna as
being "in empty space", that will account for much of the loss seen when it
is mounted to the sat, which in your design by definition is very close to
the sat frame, and thus both the electrical and RF grounds. Have your
modeller check to see if they have the sat frame, and any conductive
panels, in their model; if not you'll have some (possibly large) matching
adjustments to do.
A 1/4 wave piece of steel measuring tape needs to be at 90 degrees from all
nearby metal to be an actual "monopole" antenna. If you lay it along the
side of the sat, the nearby metal (grounds) will soak up much of the signal.
If I remember right, Prof Campbell's prior-to-CubeSat project (name is
escaping me at the moment) incorporated a proven loop design. I don't
remember the freq though. You might want to check your spec against that one.
If you haven't already, check the entire assembly (antenna on sat) with an
SWR analyzer, or preferably a network analyzer, to make sure the
transmitter is "seeing" a 50 ohm RF load at the input of the antenna line
at your transmit freq. While this doesn't guarantee the antenna is
actually an antenna and not a resistor, it does give a basic check that the
matching network is close for your situation.
GL, Mike N2VR
------------------------------
_______________________________________________
Sent via amsat-bb(AT)amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
http://amsat.org/mailman/listinfo/amsat-bb
End of AMSAT-BB Digest, Vol 3, Issue 193
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