MON sounds different LSB to USB...??

[kc2rgw]

Another n00b question, three days in, loving the radio. I'm up on the newest beta 2.0b firmware and the 2.7.x fork of Thetis.

I'm probably overlooking something but if I have MON on, listening to myself talk, there is an odd, almost like a reversed phase type difference in sound between LSB and USB. I use headphones doing this so it's pretty obvious.

I'm sure the RX filter is the same for both when doing this and I'm sure the TX filter is the same. As far as I can tell the Audio and DSP settings remain the same as I toggle LSB to USB too.

PS-A is toggled off when doing this.

I can't explain the difference.

Anyone else notice this?

Thetis 2.7.0 3/1/20
Firmware is 2.0b
Anan 7000 DLE MkII

[W4WMT]

Yeah, you're not wrong, most people don't even notice it though. The MON system is a bit crude, in that what you are listening to is the complex baseband (I/Q) signal being sent out to the DUC in the radio hardware. So it's not real audio per se. Somewhere in the bowels of this forum is an erudite explanation of the MON system given some time ago by Warren NR0V, along with some ideas on how it might be improved (given the inspiration and programming skills that would be required).

73, Bryan W4WMT

[kc2rgw]

Ah ok, thanks for replying, so it isn't "just me".

I was a front of house sound engineer for a number of years, touring and clubs, so I almost unfortunately notice things like this.