Flight Review Log Analysis - Parameters meaning

I’m currently trying to analyze some results of my flights through the Flight Review website and I also use this library to automate some data extraction.

One possibility is to convert the ulg file into csv to make it more readable. I’ve noticed some difference from ulg file to another that make hard to compare the different flights.

To be more specific I’m interested in the GPS performance (jamming and horizontal/vertical precision), I spotted those parameters as eph, epv and jamming.
The analysis guide here tells that eph should epv less than 2 and 1 meter normally, but in some files theses values can go up to several hundreds of thousands of meter, which makes no sense.

My question is therefore: are there other parameters that can help correcting/adjusting eph and epv ?
I noticed for example that hdop and vdop also change from scale with the 2 others, but I can’t find any explanation on what they represent…

[TO BE NOTED]: I can’t join ulg/csv files directly, so you will find on this link the files to upload.
There 4 of them, paired 2 by 2, the ulg file that can be uploaded to FlighReview if needed, and a csv file that extract the message ‘vehicle_gps_position’ to get some data for gps performance.
All the name of parameters I quoted come from the csv file.
(If you want to reproduce the manipulation, you should install the library I mentioned and use ulog2csv command).

Thank you !

@admins someone has any idea ?