comments on synchronous AM
Thank you for adding this a few months ago! I've wanted it for some time.
Some comments/questions. In the "SAS" (stereo) mode you put the LSB and USB on opposite channels, which is really ISB (Independent sideband) with AFC. That's one way to do it; the other is just like I/Q mode except you phase lock the carrier to the +I axis. Since there's no real AM analog stereo anymore I suppose ISB is more useful.
I assume that in SAM (synchronous mono) mode that you do put the carrier on the +I axis and then put the I axis signal on both channels?
Is the carrier loop bandwidth set by the PLL bandwidth setting in the "I/Q display extension" window? I sometimes have trouble tracking carriers, e.g., Voice of (North) Korea's H3E transmissions on 6070 kHz. H3E is upper sideband + carrier, e.g., as on CHU. I can't tell if VoK's carrier is reduced amplitude, which could be part of the problem.
Some comments/questions. In the "SAS" (stereo) mode you put the LSB and USB on opposite channels, which is really ISB (Independent sideband) with AFC. That's one way to do it; the other is just like I/Q mode except you phase lock the carrier to the +I axis. Since there's no real AM analog stereo anymore I suppose ISB is more useful.
I assume that in SAM (synchronous mono) mode that you do put the carrier on the +I axis and then put the I axis signal on both channels?
Is the carrier loop bandwidth set by the PLL bandwidth setting in the "I/Q display extension" window? I sometimes have trouble tracking carriers, e.g., Voice of (North) Korea's H3E transmissions on 6070 kHz. H3E is upper sideband + carrier, e.g., as on CHU. I can't tell if VoK's carrier is reduced amplitude, which could be part of the problem.
Comments
It has its own internal PLL code and does not use Christoph's C++ PLL code that is shared by the IQ and timecode extensions. Comments in the SAM code mention that the PLL zeta and bandwidth should probably be adjustable for varying conditions (e.g. dx, "medium", "fast"). Right now they default to a zeta of 0.65 and b/w of 200 Hz.
With the recent reorganization of the noise blanker/filter controls there is now some empty space on the audio tab of the main control panel. Perhaps some SAM PLL adjustment controls could be added there.