CAT the LO?

[KD6RF]

Hi All - new user here...

"The Goal" -
1) Use a CAT control serial input to adjust the received frequencies of ALL RX's to compensate for Satellite doppler.
2) Waterfall should show a straight line for a dopplered passband signal(s) (meaning that the frequency scale should slide with doppler while the passband(s) remained fixed in their clicked locations). I call this "Scale Slider" mode (as opposed to the undesirable "Passband Slider" mode) - perhaps there's already a terminology for these modes?


"What Works" -
I already have a working doppler-correction-serial source - this works correctly with HdSr, SdrUno etc. It ALSO correctly moves the frequency of THE MAIN RX0 of SdrConsole (so apparently SdrConsole understands the CAT input just fine).


"What Doesn't Work" -
1) The CAT serial input ONLY corrects RX0 - additional RX's DO NOT follow the doppler correction input.
2) The passband "slides" while the frequency scale remains fixed. While this does give a proper doppler corrected audio output, the waterfall shows a curve instead of the desired striaght line for our received signal.


Sorry if I am not using the standard terminology (if there is such) - but I *believe* that the CAT info needs to be CONTROLLING THE LO, NOT the RF frequency, and that the frequency scale(s) scale must slide with changes in LO frequency. RF frequencies for all receivers stay stationary on the spectrum/waterfall in their clicked locations as the delta between RF(s) and the LO update with the CAT input.


Help! - can anyone point me in the right direction to set up SdrConsole to achieve these goals?


Here's what I am calling the DESIRED "Scale Slider" mode:



Here's what I am calling the UNdesired "Frequency Slider" mode:

[Max]

Help! - can anyone point me in the right direction to set up SdrConsole to achieve these goals?

Apologies for ignorance if I don't fully understand what you are trying to achieve, but are you not trying to do things the opposite way around to normal?

SDRC will control the doppler and apply it as necessary via CAT to track the external receivers with SDRC will it not? You seem to be trying to do it the other way around?

The correct doppler compensation that you describe is already built in to SDRC:

https://www.sdr-radio.com/tracking

As I say, maybe I have not fully understood your requirements, in which case someone should be along shortly who does!

73

Max

[KD6RF]

.
I have additional experiments I wish to run (slow freq hopping, slow chirping, etc.. for a QRM dodging project). I simplified my post to eliminate those Details Details Details

In order to do this, I need CAT control from external program. As you can see, external CAT works with HdSdr.... and I need SdrCon to work the same way.
.

[Simon G4ELI]

Have you seen: https://www.sdr-radio.com/SerialPort specifically https://www.sdr-radio.com/SerialPort#Commands?

Also, there is built-in Doppler https://www.sdr-radio.com/satellites.

You should be able to accomplish your goals.

[KD6RF]

As said, I already have some serial CAT control working - and from the link it looks like I can write to each RX - thanks Simon, I shall give that a try!

The other issue doesn't seem to be addressed (or am I missing something?) -- I need help with getting CAT control to produce a display with a frequency scale that "slides" while the passband remains fixed...in order to get the desired straight line for our dopplered received signal.
This is a format issue inside SdrCon somewhere.

I hope there is maybe a configuration button somewhere that controls this feature?

I want the display to look like this:

[Simon G4ELI]

Well,

You really should let the satellite window handle the Doppler; this adjusts the data as it's received from the SDR, so you don't have to worry about frequency correction. I do know that this works.

Look at the link - use FA, FB, FC... for RX0, RX1, RX2. So whatever value you set with FA, FB, FC is applied to RX0, RX1, RX2.

If you just use an external program to set the RX0 frequency then yes, you'll see signals shifting.

So, just try the satellite option, it'll give you perfect Doppler correction.

[KD6RF]

doh !! cross posts - I hit "submit" before I was done... then the approval delay for new poster dorks like me ------ please see edited response above.

[Simon G4ELI]

OK,

Please, please, please run the satellite interface. The only display I can create for you is one with perfect Doppler correction.

If you want to apply Doppler yourself then use FA, FB, FC. SDR Console will not care if you apply Doppler this way, it'll just set the RX frequency accordingly.

If SDR Console doesn't do what you want then show me screenshots of SDR Console, not HDSDR.

[KD6RF]

Not sure what you mean by show a screenshot of Sdr Console? --- My first post shows a screenshot of Sdr Console as it produces the curved display from CAT input. The HdSdr pic shows the straight-line "Scale Slider" mode that I'm after. SdrUno also shows the desired straight line from CAT control (i think in both HdSdr and SdrUno, "FAnnnnnn" controls the LO, as opposed to the tune frequency?).

Anyway, thanks much for the replies. Maybe it turns out that SdrCon doesn't quite handle displays that fits my project.

[Simon G4ELI]

Hi,

You really must try the satellite support in SDR Console, this does what you want. As HDSDR and SDRUno work for you then maybe best to stick with them.