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TechSat(GO-32) telemetry, my analysis



Hi, all

I tried to analyzed the telemetry of TechSat(GO-32). The raw frame was
captured by WISP program and the KISS log was contributed by Mineo, JE9PEL. 
Everyone who interested can obtain the KISS logs here. Attention they are
archived by lha archiver.
10916tec.lzh  ... captured on Sept.16 00z  0.2kbytes
10917tec.lzh  ... captured on Sept.17 00z  0.2kbytes
10919tec.lzh  ... captured on Sept.19 01z  0.3kbytes

http://www.ne.jp/asahi/hamradio/je9pel/

To say short, I looked into them but a few success. The results I got is
a readable ASCII string 'TechSat-V7' and UNIX timestamp are embedded in tlmetry.
 
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This is an example of a raw packet frame from TechSat(GO-32).
Every frame the bird sent has 44 bytes. 
Don't count the begining 'C0 00' and ending 'C0' because they are just
capsule bytes added by KISS TNC, not from the bird.

C0 00 0A 0B 15 00 8C 01 49 07 FF 35 54 65 63 68 53 61 74 2D 56 37
2E 32 00 44 00 00 00 00 1E 23 10 00 40 10 05 00 00 00 00 00 61 0E 02 00 C0

All infomation I have on TechSat beacon is follows;
assib> The telemetry is not sent in AX25 but is HDLC framed so
assib> a TNC in KISS mode will decode it.

My analysis is;

0A 0B 15                .... (1)
00 8C 01                .... (2)
49 07 FF 35                      .... (3)
54 65 63 68 53 61 74 2D 56 37    .... (4)
2E 32 00 44 00 00 00 00 1E 23 10 00 40 10 05 00 00 00 00 00 61 0E 02 00 ....(5)


(1) addresses(extended) '0A 0B' and control field '15'..?
(2) no idea. seemed to be always fixed.
(3) the 4 bytes(32bits) '49 07 FF 35' is UNIX timestamp.
    '35FF0749' in hex means 'Wed Sep 16 00:33:43 UTC 1998'. 
(4) always readable in ASCII. Fixed. This 10 bytes mean 'TechSat-V7'.
(5) may be an infomation. Almost all bytes seem to be fixed but for one.
    The value of the second bottom byte('61' in above example) changes often.
    no idea what does the each byte in section(2) & (5) mean respectively.

Here is another example. 
On the next transmission(30 seconds later above),

0A 0B 15
00 8C 01
67 07 FF 35                      ....means 'Wed Sep 16 00:34:13 UTC 1998'
54 65 63 68 53 61 74 2D 56 37    ....means 'TechSat-V7'
2E 32 00 44 00 00 00 00 1E 23 10 00 40 10 05 00 00 00 00 00 50 0E 02 00

And on the next day(00z 17-Sept-98),

0A 0B 15
00 8C 01
53 54 00 36                      ....means 'Wed Sep 17 00:09:56 UTC 1998'
54 65 63 68 53 61 74 2D 56 37    ....means 'TechSat-V7'
2E 32 00 44 00 00 00 00 1E 23 10 00 40 10 05 00 00 00 00 00 5E 0E 02 00

Gee,,, what's fun in this work ?
Any comments to resolve a puzzle are welcomed.


de Kazu Sakamoto, JJ1WTK
----
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