Im not following this closely, but the transponder I think is inverting. Thus the uplink dopper is subtracted from the downlink dopper whereas the beacon on the satellite is impacted by the full dopper of the speed of the spacecraft. So they will not be the same. Do the math and see if that comes out to the 1.26 you observed.
Bob, WB4APR
-----Original Message----- From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Dani EA4GPZ Sent: Monday, October 30, 2017 5:53 PM To: amsat-bb@amsat.org Subject: [amsat-bb] FO-29 transponder block diagram
Hi all,
A few days ago I have transmitted and recorded a (low-power) FT8 signal through the FO-29 linear transponder to test some Doppler correction algorithms I'm developing (see http://destevez.net/2017/10/wsjt-x-and-linear-satellites-part-ii/)
After Doppler correction, I'm left with a linear frequency drift both in my downlink signal and in the satellite CW beacon. However, the drift rate of my signal and the beacon are different. Specifically, my signal drifts 1.26 times faster than the beacon. I suspect that this drift is due to one of the local oscillators in FO-29.
To understand this better, I need to look at a block diagram of the FO-29 linear transponder. The best I've found is this:
http://www.jarl.org/English/5_Fuji/systeme.gif
However, I need something similar to this:
https://funcubetest2.files.wordpress.com/2010/11/funcube_rf_board_block_di agramv2-1_pa3weg_open-1.pdf
Since I need to see the frequencies of all the local oscillators involved in the transponder and CW beacon.
Is there a more detailed block diagram for FO-29 or does anyone know something about this information?
73,
Dani EA4GPZ. _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb