I'll have to wait til my RTL order arrives in order to get to the bottom of the issues, but there is a gain setting parameter (-N) that might also work.

Many thanks for your feedback.  Would be interesting to have you set up scope.py using a trunking (-T) configuration - I'd also be curious to see how you make out on LSM voice channel decoding.

The constellation plot shows that there is a nice zone in the vicinity of the origin (0,0) where there is no signal energy, but that the symbols are not all concentrated at the circumference.  This plot is ultra-typical of LSM.  If you have a directional antenna you can use that as a guide to aiming the antenna for best reception - just adjust such that all the symbols move away from the center...

Max