The TXT-file contain the GPS data. In the IMP-file you find the lenght of the servo impuls on the wire with the orange connector (if connected to the receiver). If the wire is connectet to the receiver, you can also use this for setting the startlocation of the plane. See the information at the update file for de MGPS
www.jetimodel.com/en/katalog/Duplex-2-4-...EX/@produkt/MGPS-EX/
With the program GPS Track Analyse
www.gps-track-analyse.de/ you can view the GPS data.
Install the program
Rename the "TXT" extension to "NMA".
Open the NMA file with te program. Do not forgot to select the filetype "nma".
If you have a Jeti transmitter it is easyer to log de GPS-data in the Jeti transmitter. You can download the logfile from the transmitter and import it via JPB-Read in the Jeti Flight Monitor or another program for visualising Jeti logdata.