Ok, success with decoding 400k baud packets from the 1.6M I/Q file very kindly provided earlier. You DO get a number of valid frames with the CRC check enabled, but naturally even more when both the ‘OK’ and ‘Fail’ outputs are monitored. (as shown in the screen shot of the GRC file farther down)
… please note the signal after muting the DC spike and shifting over a bit to center the data packet:
(this may or may not be the exact center - please experiment & improve!)
Here is the entire flowgraph (using a short crop of the original 1.6M I/Q file so there’s no wait for frames)
… which is available at the following URL if anyone would like to use portions of this in a flowgraph arranged to suit your personal preferences. (also please note that I’ve only tested w/ the 32-bit float I/Q file input - audio input blocks are present but I don’t expect that 400k baud can be decoded from audio) {so, I might add an SDR Source in the flowgraph for live decoding - but for now at least we can test w/ an I/Q file source}