Receiver Offset Capabilities

[drmgcm69]

Hi JF9SOM,

I wanted to ask if you can add a receive offset capability that can be stored for each satellite, that way the operator does not have to keep finding themselves at the start of each pass?

This is especially useful on all radios even those with RIT capability, giving the operator maximum time on the satellite pass.

73
DM

[JF9SOM]

Hi DM,

Thanks for the suggestion! I've implemented a persistent per-transponder RX offset.

In the Radio Control tab's Satellite panel, there's now an "Offset" spinbox next to the NORAD ID display. The value you set there (in Hz, adjustable with the up/down arrows or by typing directly) is saved per transponder and continuously applied as a correction to that transponder's downlink center frequency, before Doppler correction. It's automatically restored whenever you reselect that transponder, and it's preserved when you press Tune (T) — so a satellite's known, fixed frequency error (e.g. from TCXO aging) no longer needs to be rediscovered at the start of every pass. (This release covers the downlink/RX side only — the uplink/TX side, and any real-time in-pass drift, are still handled by the existing Lock feature.)

This is included in v0.3.7, which is now released: https://github.com/JF9SOM/FBSAT59/releases/tag/v0.3.7

Give it a try and let me know how it goes!

73
JF9SOM

[drmgcm69]

Hi DM,

Thanks for the suggestion! I've implemented a persistent per-transponder RX offset.

In the Radio Control tab's Satellite panel, there's now an "Offset" spinbox next to the NORAD ID display. The value you set there (in Hz, adjustable with the up/down arrows or by typing directly) is saved per transponder and continuously applied as a correction to that transponder's downlink center frequency, before Doppler correction. It's automatically restored whenever you reselect that transponder, and it's preserved when you press Tune (T) — so a satellite's known, fixed frequency error (e.g. from TCXO aging) no longer needs to be rediscovered at the start of every pass. (This release covers the downlink/RX side only — the uplink/TX side, and any real-time in-pass drift, are still handled by the existing Lock feature.)

This is included in v0.3.7, which is now released: https://github.com/JF9SOM/FBSAT59/releases/tag/v0.3.7

Give it a try and let me know how it goes!

73 JF9SOM

Hi JF9SOM,

Many thanks for the addition of this feature, appreciate it, I will give it a try tomorrow when I am next working some Sats.

Best 73

DM

[drmgcm69]

Hi JF9SOM,

Many thanks for the addition of this feature, appreciate it, I will give it a try tomorrow when I am next working some Sats.

Best 73

DM

[drmgcm69]

Hi JF9SOM,

Rx offset works, so thank you for adding the features.

73
DM

[drmgcm69]

Hi JF9SOM,
I know you said the offset stores into the software for a satellite say RS-44 for example, but when you change to another satellite let's say JO-97, then go back to the previous one RS-44, there is no offset displayed in the spin dial for RS-44, where did it go?

It really needs to be displayed in the spin dial, since offsets change, especially on AO-73 & AO-7 B mode, they change the most and you need to adjust.

Can this be implemented?

73

DM

[JF9SOM]

Hi DM,

Thanks for the detailed report. I dug into this, and the value was never actually lost from the database.

The root cause was a display-only bug: the code path used when reselecting a satellite from the main list wasn't reading the rx_offset_hz column when it fetched the transponder list. So the saved value kept being applied correctly to the Doppler correction on every pass behind the scenes, but the spinbox display itself reverted to 0 after switching satellites and back. The actual receive frequency wasn't affected.

I've fixed the display bug and just released it as v0.3.14: https://github.com/JF9SOM/FBSAT59/releases/tag/v0.3.14

Switching between satellites (e.g. RS-44 -> JO-97 -> RS-44) should now correctly redisplay the saved value each time. For satellites that need frequent adjustment like AO-73 or AO-7 Mode B, you can still adjust it on the fly with the up/down arrows or by typing directly, and each transponder keeps its own independent value.

Please give it a try and let me know how it goes.

73
JF9SOM

[drmgcm69]

Hi JF9SOM,

Yes that works, now you see the offset for the satellite selected, thank you.

73
DM