IMHO, You are asking the PostCard to do too much in “real-time”
As a reference, below are the NMEA Settings that I use for the PostCard as a RTK Rover:
1) Message RMC: 1
2) Message GGA: 1
9) Message GST: 1
I would prefer to have GSV every 10 seconds, but the LG290P Firmware only allows 1/Off at the moment, so GSV stays OFF for now.
My opinion is: If my data collector doesn’t need the NMEA message - then don’t send it.
This is especially true for you since you want to also save the RAW Observables for post processing.
The Screenshot of your text file :
The GNSS Observables are not going to be in a “Human Readable” format.
I don’t think you want the NMEA saved however.
Post Processing from Postcard:
As @swells stated in this post, the conversion is successful from a PostCard that was logging RTCM in Base Mode. So I expect you can be successful with your PPK goals, once that specific workflow is established.
My assumption is: You want to post-process GNSS data with PPK for PostCard positions that were originally computed in real time using RTK.