brainwagon "There is much pleasure in useless knowledge." — Bertrand Russell

27Apr/080

Cubesats away!

Well, the satellite launch that I've been waiting for happened. On the first pass I thought I was setup to record the Delfi C3 telemetry, and even thought I heard a signal, but it turns out it was probably just a local birdie. The second pass of the satellite cluster was only a 9 degree pass, and this time, I decided to focus on SEEDS, which I had heard was actually heard during the first pass. I recorded the following, just using my voice recorder:

SEEDS recording, second orbit over the west coast

I can read out the letters S E E D S rather easily, so I am pretty sure this is it.

Addendum: I ran the audio through my crude spectrogram code, and got the following picture of one of their telemetry packets...


SEEDS telemetry

Each vertical column represents 1/50th of a second of audio.

Addendum2: Here's the same image, but with the decode overlaid.


SEEDS telemetry, labelled

If I read the telemetry documentation correctly, this is a G0 mode message, and D19 indicates that the lithium/ion batteries are at 4.1volts, and the bus voltage is very nearly 5v.

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27Apr/081

General Decimal Arithmetic

While trying to find out if Python included some built-in capabilities for dealing with BCD numbers (it appears not) I encountered this rather interesting page about decimal arithmetic.

General Decimal Arithmetic

27Apr/080

AO-16 gone quiet…

The news is that satellite AO-16 has gone quiet. We've been assured not to panic:


Hello all,

There are reports at http://oscar.dcarr.org/ that AO-16 has gone silent.
Should this be the case, there is no cause for alarm.  Over the last month
AO-16 has gone from full illumination (0 minutes of eclipse) to over 250
minutes of eclipse.  Since the bird has no fancy housekeeping code running,
a reasonable explanation is that the battery voltage dropped low enough to
put the bird into a protected (and silent) mode.

Over the next few days I'll work at collecting telemetry and restoring the
voice mode operations of AO-16.  Please refrain from transmitting to the
satellite until further notice.

On behalf of the AO-16 Command Team,

Mark L. Hammond  [N8MH]
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