Direct I/Q and Spectrum Lab

[vk2atw]

Hi
I'm trying to route VAC 1 to the Spectrum Lab software using Direct I/Q. I think i have the audio route setup correctly as i'm getting some very low input however there seems to be a gain/volume problem - the signal in Spectrum Lab is very weak.

Has anyone got this software working with Thetis?
Any ideas with the gain issue - does gain even work when you are sending I/Q direct to the VAC (it soesn't seem to have any effect).

I can route standard audio with no problems - i.e. as soon as i uncheck Direct I/Q output to VAC i get the full audio signal in Spectrum Lab.

I am routing the VAC's through Voicemeeter Potato if that makes any diffeerence?

I want to use the I/Q data to ensure i don't have any processing from Thetis of the signal from my radio.

Thanks for any pointers/assistance.

Cheers Alan

[DL2XY]

Hi Alan,

it's all about dynamic range. 80m bandnoise usually is about -120dB fullscale, input noise of the Anan's somewhere at -150dB FS.

You have to make sure that your audio chain and the used spectrum app supports HDR. 16bit resolution is definitly not enought (only 96dB), you need at least 24 bit, better 32 bit resolution.

I am using muzychenko VAC und self written apps for display and measure direct IQ output and all is working very fine.

greets Walter

[vk2atw]

Thanks Walter

I will go back and ensure entire signal chain is 24 bit. I suspect that might be my issue. Will report back.

regards Alan