I was able to have a short QSO with Rick, W2JAZ tonight about 01:58Z on AO-73. As I’ve been seeing over the past couple of weeks, the uplink offset is pretty far off the published specs and seems to get worse with time. Despite using TLEs from today, the Doppler correction seems to be off substantially as well, shifting about 3 KHz from start to finish (despite TX and RX Doppler correction from Sat32PC). I don’t have these issues with either FO-29 or AO-7.
After calibrating Sat32PC at mid-pass, my DOPPLER.SQF line value for CW was:
“AO-73,145957.52,435160.48,CW,CW,REV,,, Transponder”
Note that the published figures says that 145.957.5 should be about 435.142.5, so my correction value is about 18 KHz higher than published values. These are with respect to the satellite (what the satellite sends and hears). At my end, the IC-9100 RX was 145.964 and TX was 435.162 after both were corrected.
So the big mysteries that haven’t been answered since AO-73 transponder was turned on in November of 2013, are:
- How come the Doppler isn’t adequately corrected given most recent NORAD TLE values?
- How come the TX to RX relationship is so out of wack?
