Subject: Athenoxat-1 new beacon
From: Yesie Brama
Date: Mon, 11 Dec 2017 11:06:26 +0000 (UTC)
Dear all,
Greetings from Athenoxat-1 team :)
It's been a while and we're glad to inform that our satellite Athenoxat-1
(ATX) is doing well until today, entering into her 2 years life in space.
To celebrate this event, we have modified the data beacon hopefully for
the pleasure of HAM activities around the world.
As we understand, HAM community has been able to decode ATX data beacon
using HS Soundmodem (version 0.15b?). So just to explain the new structure
of the data beacon: Apart from the COM header/sync marker etc, the real
data size for each packet expected will be 216 bytes.
The first byte = type of data of either {2, 4, 5} which means {in-house
icon image, thumbnail images produced by ATX, the text-note to explain
the image contain in the thumbnail}
For the type of data 2 and 5 (single chunk concept):
The next 2 bytes = the variable file size of the icon image / text-note,
for example 192. Thus the next 192 bytes will be thecontent of the image/
text-note itself.
The next remaining (216 - 1 - 2 - 192) = 21 bytes can be ignored.
he icon image is in .bmp format & text note is ASCII characters.
For the type of data 4 (multiple chunks concept):
The next 1 byte = the variable size of last remaining bytesNext 2 bytes=
the variable file size of the thumbnail imageNext 2 bytes = chunk marker
For example, the thumbnail image is 3748 bytes. The beacon transmission
will be chunk by chunk with each chunk has size 210 bytes.
Therefore roundup (3748 / 210) = 18 with the modulus or last remaining
bytes = 178 bytes.So in this example, each packet will have the first
4 bytes the same value, and the next 2 bytes is chunk marker, and next 210
bytes will be the content of thumbnail image and should expect 18 packets
transmitted. First packet will have chunk marker = 18 and next packet
decrements to 17 and so on. The last packet should have chunk marker = 1.
Specific to the packet with chunk marker = 1, the remaining
(216 - 1 - 1 - 2 - 2 - 178) = 33 bytes can be ignored.
The thumbnail is in .jpg format. Should there be any difficulty in
reconstructing the data, you can send the recorded packets (not just
the screenshot) you've received to us, and we'll be glad to help.
In addition, we would really like to send the overdue QSL cards to you
who has been curious and received our ATX beacon last year.
We are thinking to send this QSL card via ATX transmission too. What is
needed is only for us to make the appointment :)
Please let us know your confident good quality AOS of ATX and for how
much duration. Then we'll upload to the satellite Flight Planner so that
when ATX is passing your AOS time, she'll start transmitting the chunks
of the QSL card.
We've prepared the QSL cards and they are about 30kB size, thus the
required transmission duration should be less than 5 minutes.
This is because the chunks will be sent in the interval of 2sec, as not
tostress ATX radio. In case there's interference / bad connection during
the transmission, we can resend you only the specific chunk markers that
you miss at the next appointment time.
We hope this activity will spark the interest of HAM people around the
world who can receive ATX beacon. Since this is a kind of new experiment/
features of ATX, let us please test it with your first before we publish
this information to the public. When this new features are confirmed good,
we'll update our website too with this detailed information. Looking
forward to your feedback then. Thanks much in advance for your time.
Kind Regards, Athenoxat-1 Team, Microspace Rapid 9V1FC / 9V1SQ