[Gpredict-discussion] tracking fixed sat freq. FT857D

[Don R. <w9d...@gm...>]

I am trying to get the rig control/Doppler shift correction working.
I got rigctld talking to my radio (FT857d). gpredict is talking to rigctld
ok

Goal, use gpredict to track ISS and correct ft-857d for RX/TX Doppler.
ISS transmitters are fixed freq 145.825. Have gpredict set TX/RX freqs
on 857 VFO A for RX, VFO B for TX and set split mode to switch.

gpredict as soon tracking is engaged the program rx freq starts drifting
and in time it's so far off you will never pick up the bird. If I am
manually in control of the program I can keep clicking on "T" to keep
tuning it. but I want to leave it unattended for uploading/gating aprs
position packets.

I think I understand what is causing the rig control function to go wacky
is that how both doppler correction and reading the rx/tx freqs from the
radio at the same time is going on. It sets the
doppler, then reads the radio, and a slow drift starts.

Is this drift just a quirk of the FT857/897/FT100 radios. I tried all 3.
I even tried using the ft100 for RX only and FT897 for TX only same issue.
I still got the drift without touching vfo on the radios.

Also the "special FT857/897" mode does not seem to be working, it is not
setting the
A/B vfos one for TX one for RX so you can use "split" and have both
corrected.

Any idea's on what I can try?

--
Don Russell, CBRE CBNT
W9DRR - ARRL OES, Technical Specialist