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

Automated Cute 1.7 Telemetry Capture

Just like to share my experience with automated CW Telemetry capture from Cute 1.7.
Using CWGet and empirically deduced optimised parameters as below:-
Main Filter 600 Hz.
Burst Filter 200 LPM
Local AFC Deviation 1000 Hz
Global AFC Deviation 3000 Hz
AutoThreshold ON.
and select OpenTextCaptureFile to store received telemetry.

I also record the audio to a .wav file using AO40Rcv and monitor doppler
etc on AO40Rcv's display.

Updating my FT736R (Sattrak3) with 100 Hz frequency adjustments.
Using centre frequency of 437.3805 (provides a nominal 1100 Hz tone on receive).

The above are parameters of a work in progress.
My major task each pass is to select either RHCP or LHCP to maintain the best S/N.

The following block of telemetry was recovered
after filtering out the noisy characters with 'x'
and inserting CR/LF prior to cute.

2nd March 0836 - 0840 UTC 34 Degree Elevation

                              38 70 41 xx 0f
cute 777772 89 ce ac 76 5e x2 38 6a 42 95 0f
cute 777772 89 cd ax x8 5e 42 38 6d 45 93 0f
cute 777772 88 cd ad 78 5e 42 38 71 4b 8f 0f
hi hi de jq1ycc lss.mes.titech.ac.jp
hi hi de jq1ycc lss.mes.titech.ac.jp
cute 1.7 6782000a00000032
cute 1.7 6782000a00000032
cute 777772 x9 ce xd 77 5e 42 39 6c 40 9x 0f
cute 777772 88 cd ad x8 5e 4x x8 6x xx 9a 0f
cute 777772 88 cd ax 77 5e 42 38 xx 40 96 0f
cute 777772 88 ce ac x7 5e 42 38 6c 4d 8c 0f
cute 777772 88 ce ax x7 be 42 38 6d 4f 8c 0f
cute 777772 88 cd ad 76 5e 42 3x 6d xb 8e 0f
cute 777772 88 cd ad xx xx 42 38 71 5x 96 0f
cute 7777xx 88 cd ad 78 5e 42 38 6d 49 90 0f
cute 777772 88 ce ac 79 5e 42 38 6b 50 8d 0f
cute 777x72 88 cf ad 78

Now some working notes.
Why CWGet?
I tried a number of programs (Google search) and found CWGet to have the best performance with poor S/N signals. Then again I only
tried 4 programs.
I have not evaluated Hamscope.
The main filter setting of 600Hz and the RX update at 100 Hz appear to be the best COMPROMISE for the rate of change of doppler
during apogee.
At AOS and LOS the default main filter setting (280 Hz) will copy signals down into the noise to a point where I cannot decipher,
but CWGet will capture an extra 4 0r 5 characters (all legit too).
The RX update is also a compromise at 100 Hz.
I evaluated 10, 25, 50 100 & 200 Hz. However during apogee (max doppler) the RX update introduces a "chirp" that can be mistakenly
identified as a "dot".
I find the 100 Hz update provides minimal errors.

Hope this motivates others to push the boundaries.
Sure beats scribbling down code, changing polarisation etc. during the passes, then having to replay the pass to check and
re-confirm your received code.
My cw capability is fair/good, but would not gamble my life on it.

Colin VK5HI.
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