Working Falconsat-3 with hardware TNC is piece of cake. compared to combination of multi-software to read data and keying the rig .
TX LINE -WISP-> HW VSP-> SOUMDMODEM -> 9600 DATA --> Keying circuit
RX LINE -SDR-> SOUNDMODEM (FULL DUP)
I succeed to upload a message to FS-3 .
Also got the "NO -5" errors.when I requesting the Dir.
Other problem during handshake, the transmitter noise desensitization (desense) the SDR receiving signal . (instead dozens ferrite choke on every wire and coax ). All equipment has a decent earthing too.