AO-16

AO-16 reconfigured.


Subject: [amsat-bb] AO-16 reconfigured.
From: Andrew Glasbrenner
Date: Tue, 22 Jan 2008 13:47:42 -0500

Since AO-16 was recovered approximately 6 months ago, the command team has
attempted to reload the satellite software almost a dozen times without
success. Subsequently a series of memory tests were performed which points
towards a hardware failure which prevents restarting the spacecraft software
successfully. This team included Bruce Rahn WB9ANQ and Jim White WD0E
advising Mark Hammond N8MH as the primary groundstation. Mark put in many
early hours during the multiple reloads and test sessions, with Bruce, Jim,
and others advising. Thank you to all involved for your hard work.

After the conclusion that the spacecraft computer system was damaged and as
discussions about decommissioning were taking place, Jim recalled a series
of low level commands included in the spacecraft design by Tom Clark, K3IO
during construction. One of these commands allows an uplink receiver to be
directly tied to a downlink transmitter. The twist is that the uplink is
regular FM but the downlink via the BPSK transmitter is DSB (Double
Sideband). Mark placed the satellite in this mode early this week and some
testing was undertaken. The satellite hears VERY well, and the reduced
bandwidth by using either USB or LSB on the groundstation receiver allows
for a very robust downlink. Tuning the downlink is just like on a linear
transponder, meaning it is tight and with fast Doppler. Uplink tuning is not
required, just as with the FM mode V/U satellites. QSOs were made between
N8MH, WD4ASW, KO4MA, K5QXJ, and WA6FWF. My personal observations include
being able to access and hear the satellite within one degree of the
horizon, much lower than any other current bird for my QTH. This should be
an easy satellite with omni antennas and a 70cm preamp.

With that explanation, I'm happy to open the satellite to general use on
voice for a test period. Please submit reports either to the -bb or to
ao16@amsat.org . The uplink is 145.920 FM, and the downlink is 437.026 SSB
+/- Doppler shift. Please restrict your uplink power to a reasonable level,
and do not transmit without being able to hear the downlink. All the general
single-channel guidelines apply. Enjoy this bird's new life!

73, Drew KO4MA
AMSAT-NA VP Operations


-----------------------------------------------------------------------------

Subject: [amsat-bb] AO-16 status report
From: Mark L. Hammond
Date: Tue, 4 Mar 2008 11:35:07 -0500 (EST)

Hello all,

Ronald, I'll take your message as a prompt to provide an AO-16 update!
AO-16 is certainly not dead. It is doing quite well in its current mode.
Below is the current operational configuration for AO-16:

(available from: Sattelite Detail - AMSAT OSCAR 16)

Mode FM Voice Repeater (Downlink is double sideband.): Operational
Uplink:         145.9200 MHz FM
Downlink        437.0260 MHz DSB (LSB and USB)

The plan is to continue this mode of voice operations "until further notice."

AO-16 has been in full sunlight (no eclipse periods at all) for several
months. That is about to change later this month! Short eclipse periods
will begin at the end of March and will increase steadily until early
July--at which point the eclipse periods will increase to about 26 minutes
each orbit. We'll have to watch this old bird and its batteries as the
eclipse periods increase.

It is possible that the long eclipse periods may necessitate the reduction
of the 70 cm transmitter output; this is a manual process for AO-16, since
the spacecraft isn't running any housekeeping software to do it
"automagically." AO-16 is pretty loud at its current power setting, so
some reduction should have little if any user impact. Observations and user
reports will be especially helpful during April/May/June/July this year.
In order to collect telemetry, we'll need to change the satellite into its
digital mode from time to time. But this doesn't take long and therefore
shouldn't interfere much with its operations as a voice satellite.

The S-band beacon is not operational at this time. The exact status of the
S-band transmitter remains unknown; however, its last known status might be
described as "suspect" or "semi-operational" at best...(as I recall--and this
might not be accurate--there are issues with the power budget, no way to
adjust the power output of the S-band transmitter, and so on.) Given the
age of the satellite (over 18 years!), my opinion is that this falls into
the "maybe we should leave well enough alone for now" category.

(And yes, LUSAT/LO-19 is still transmitting CW telemetry on 437.125+/-
 ----if that's what you mean below?)

On behalf of the AO-16 Command Team,
-- 
Mark L. Hammond [N8MH]
Back to AO-16 index
Back to Home Page