[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Observed AO-40 FEC coded telemetry ?



Hi all,

On Saturday June 7th 2003 around 03z, 
I am sure that I observed the experimental transmission of FEC coded
telemetry of AO-40 on the S2 beacon.

Normally, the bird have been sent the blocks in the sequence of
A,E,A,K,A,E,A,L,A,E,A,M,A,E,A,N and then repeat them. However, on that
day, the IHU-2 turned on around 0245z, and a new sequence initiated since 0252z.
The sequnce I observed was an ordinally A block in 13 seconds first,
then (possibly) a FEC coded A block in around 13 seconds followed by
idle 28 seconds. The two LEDs of 'CAR' and 'CLK' on 'the Phase 3 400bps
PSK demodulator mkII' designed by James G3RUH were always active even
FEC coded blocks were sent. Unfortunately since I'm not ready to decode
the FEC coded blocks, I coundn't confirm what contained in the 13 seconds. 

I logged the sound into some .wav files by AO40Rcv written by Moe
Wheatley, AE4JY and placed them below. 

http://www.ne.jp/asahi/hamradio/jj1wtk/

The waterfall pattern is so interesting. After the conventional A block,
the many peaks around 1600Hz turned broad ones. I think it means the
scrambler in the onboard FEC encoder works well.



73, Kazu Sakamoto, JJ1WTK   kazu@jj1wtk.jp
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home